Heat and cold storage tank with counterflow heat exchanger

Abstract

A heat storage and exchanger includes a first fluid conduit, a second fluid conduit, a heat exchanger, and a storage tank. The heat exchanger is configured to transfer heat between the first fluid conduit and the second fluid conduit. The storage tank is configured to receive a thermal storage medium. At least a section of the heat exchanger is arranged in the storage tank to enable a transfer of heat between the heat exchanger and the thermal storage medium.

Description

FIELD

[0001] The invention relates to the technical field of thermal energy storage and in particular to a heat or cold storage tank with integrated counterflow heat exchanger and a system with a heat storage tank and a cold storage tank.BACKGROUND

[0002] The energy impinging on a building roof is regularly sufficient to cover the energy needed by the building at least on an annual average. For this purpose, a photovoltaic system with photovoltaic modules for generating electrical current and / or with a photothermal system for generating hot water can be used, and the energy obtained can be supplied to consumers in the building in either case.

[0003] Furthermore, additional variable energy sources can be available for use in a building, such as the waste heat of a refrigeration machine or a generated current of a wind turbine. In particular, heat pumps of different design are regularly used, for example in single-family and multi-family houses, in order to also make use of low-temperature heat sources.

[0004] However, it is problematic in all the aforementioned cases that a corresponding (regenerative) energy generation and an energy consumption by private households or industrial complexes frequently do not coincide in time, both short term and seasonally. In particular, a regenerative energy generation potential is regularly higher in summer than in winter, for example due to photovoltaics or photothermics, although a significantly increased energy consumption occurs in winter, in particular for heating and service water heating.

[0005] One possibility for decoupling the consumption and the generation of energy is constituted by thermal energy storages. These can temporarily store the generated energy in cold or heat storage in the short to long term in order to compensate for differences in the times of energy generation and energy consumption.

[0006] Conventional heat storage tanks (or cold storage tanks) comprise multi-zone storage tanks, through the central region of which a heat exchanger for inputting the heat (or cold) extends. Separated therefrom, several heat exchangers for extracting the heat (or cold) in the heat storage tank (or cold storage tank) are arranged in the outer region at different heights.OVERVIEW

[0007] The heat storage tanks (or cold storage tanks) known from the prior art are not optimized for use in a system with a photovoltaic system and / or a heat pump. It is an object of the invention to provide a heat storage tank (or cold storage tank) which is optimized for use in a system with a photovoltaic system and / or a heat pump.

[0008] This object is achieved according to the invention by a heat storage and exchanger with the features of claim 1, a system with the features of claim 15, and a method with the features of claim 16. Embodiments of the invention are specified in the dependent claims.

[0009] According to a first aspect, a heat storage and exchanger includes a first fluid conduit, a second fluid conduit, a heat exchanger, and a storage tank. The heat exchanger is configured to transfer heat between the first fluid conduit and the second fluid conduit. The storage tank is configured to receive a thermal storage medium. At least a section of the heat exchanger is arranged in the storage tank to enable a transfer of heat between the heat exchanger and the thermal storage medium.

[0010] Thus, a highly integrated heat storage and exchanger can be provided which enables to transfer heat from a solar system and, if it is currently being operated, a heat pump into the storage tank by means of the heat exchanger. If the heat pump is not currently being operated, the heat storage and exchanger can continue to be operated unchangedly to continue to transfer the heat from the solar system into the heat storage and exchanger.

[0011] For this purpose, the solar system or the heat pump can be connected to the first or second fluid conduit. A need for further adaptations, for example with regard to electrical connections, can thus be avoided.

[0012] Furthermore, as a result of its arrangement in the storage tank, the heat exchanger can enable an effective heat transfer between the first and the second fluid conduit, i.e. for example between the photovoltaic system and a cold side of the heat pump. The effective heat transfer is in particular a result of the abundance of space available in the storage tank, due to which the heat exchanger, for example as a double-pipe heat exchanger, can be formed with a large contact area between the first and the second fluid conduit. In contrast, in conventional systems, usually no heat exchanger is provided which would enable a direct and effective heat transfer between the first and second fluid conduit or between the heat pump and the photovoltaic system.

[0013] In some embodiments, the heat exchanger is arranged for the most part in the storage tank. For example, the heat exchanger may be arranged with at least half, at least two thirds, or at least three quarters of its longitudinal extent in the storage tank. Alternatively or additionally, the heat exchanger may be arranged with at least half, at least two thirds, or at least three quarters of its volume in the storage tank.

[0014] The thermal storage medium may comprise or be a liquid, in particular at room temperature. For example, the thermal storage medium may comprise water, for example at a volume fraction of at least half, at least two thirds, or at least three quarters.

[0015] However, the person skilled in the art understands that different thermal storage media can be used which do not have to be restricted to heat storage by changing the temperature of the solid / liquid storage medium. For example, a phase change material for storing thermal energy as latent energy, thermochemical storage media, or a salt dehydration storage for insulation-free long-term storage can also be accommodated in the storage tank.

[0016] In some embodiments, the heat exchanger is configured as a counterflow heat exchanger.

[0017] In corresponding embodiments, the effectiveness of the heat transfer between the first and second fluid conduit or between the heat pump and the photovoltaic system can be further improved.

[0018] The heat exchanger may comprise or be formed as a multiple-pipe heat exchanger, a double-pipe heat exchanger, a plate heat exchanger or a tube bundle heat exchanger.

[0019] The first fluid conduit and the second fluid conduit may be in direct contact in the heat exchanger and / or in a section of at least 0.5 m or of at least 1 m or of at least 2 m.

[0020] In corresponding embodiments, the effectiveness of the heat transfer between the first and second fluid conduit or between the heat pump and the photovoltaic system can be further improved. Corresponding embodiments can be enabled by the arrangement of the heat exchanger in the storage tank.

[0021] In some embodiments, the storage tank is a cistern storage. Alternatively or additionally, the storage tank may have a volume for the thermal storage medium of at least 1 m3 or of at least 2 m3 or of at least 3 m3. Alternatively or additionally, the storage tank may be adapted for an underground arrangement.

[0022] In particular, the heat storage and exchanger may be configured to be arranged in one piece, i.e. with the heat exchanger arranged therein, at least partially in the ground. After the partial introduction into the ground, connections for the first and the second fluid conduit can protrude upwards out of the ground and be available for the connection of the photovoltaic system and the heat pump, so that an overall system can be realized quickly, efficiently and cost-effectively.

[0023] In corresponding embodiments, the storage tank can provide a sufficiently large storage capacity to store enough heat (or cold) to cover fluctuations in the demand of a building over periods of months, in particular seasonal fluctuations.

[0024] In some embodiments, the first fluid conduit and / or the second fluid conduit is configured to pass through an upper surface of the thermal storage medium at least once or at least twice when the thermal storage medium is arranged in the storage tank. Alternatively or additionally, the first fluid conduit and / or the second fluid conduit may pass through the storage tank at least once or at least twice in the uppermost quarter of its height extension, in particular in the uppermost fifth of its height extension or at its upper side.

[0025] Corresponding embodiments can simplify the connection of the heat storage and exchanger to other components of the system, in particular with an arrangement of the heat storage and exchanger in the ground, in which, for example, the uppermost quarter, the uppermost fifth or the upper side of the storage tank protrude out of the ground.

[0026] In some embodiments, the heat storage and exchanger is arranged in an external region (i.e. with respect to the building), for example above ground or below ground in an environment of an adjacent building. In other words, the heat exchanger may not be located in a building.

[0027] The heat storage and exchanger may be coupled to an associated heat storage arranged in a building. For example, in embodiments wherein the heat storage and exchanger is configured as an ice storage or latent heat storage, the associated heat storage may be a cold storage. Alternatively or additionally (additionally e.g. in embodiments wherein the heat storage and exchanger forms a second heat storage and exchanger), the associated heat storage may be a multi-zone storage.

[0028] In some embodiments, the first fluid conduit and / or the second fluid conduit is configured for evaporating and / or condensing a refrigerant therein.

[0029] In some embodiments, the heat storage and exchanger includes at least one additional heat exchanger.

[0030] The at least one additional heat exchanger may be configured for thermal coupling to the thermal storage medium and / or may be arranged in the storage tank, in particular spatially separate from the heat exchanger.

[0031] The additional heat exchanger can enable a heat transfer between the storage tank, or the thermal storage medium arranged therein, respectively, and a load, or enable a heat transfer between the storage tank or the thermal storage medium arranged therein, respectively, and a further heat source or heat storage device such as a geothermal collector.

[0032] In some embodiments, the at least one additional heat exchanger includes at least one supply / discharge conduit or at least two supply / discharge conduits.

[0033] The at least one supply / discharge conduit or the at least two supply / discharge conduits may be configured to pass through an upper surface of the thermal storage medium when the thermal storage medium is arranged in the storage tank.

[0034] The at least one supply / discharge conduit or the at least two supply / discharge conduits may pass through the storage tank in the uppermost quarter of its height extension, in particular in the uppermost fifth of its height extension or at its upper side.

[0035] Corresponding embodiments can simplify the connection of the heat storage and exchanger to other components of the system, in particular with an arrangement of the heat storage and exchanger in the ground, in which, for example, the uppermost quarter, the uppermost fifth or the upper side of the storage tank protrude out of the ground.

[0036] A geothermal collector may be thermally coupled to the heat storage and exchanger. In some such embodiments, the geothermal collector may be spatially separate from the heat storage and exchanger, and may be thermally coupled to the heat storage and exchanger, for example by a fluid conduit.

[0037] In particular, an additional heat exchanger of the at least one additional heat exchanger may be coupled to the geothermal collector, in particular to thermally couple the geothermal collector to the heat storage and exchanger.

[0038] A geothermal collector comprises heat transfer conduit loops which usually run substantially horizontally in the ground close to the surface, in order to exchange heat between the adjacent ground and a heat transfer medium. Correspondingly, thermal energy can be stored in the geothermal collector or removed therefrom by a flow of a heat transfer medium through the heat transfer conduit loops depending on the respective temperatures.

[0039] The geothermal collector may be arranged laterally with respect to the storage tank.

[0040] The storage tank may constitute an energy-storing component with a high energy storage density, which can be thermally charged or discharged with a comparatively quick response. Heat losses of the storage tank can increase the temperature of the surrounding ground, which can likewise be used as an energy source by the laterally arranged geothermal collector. Correspondingly, an insulation requirement on the storage tank may be comparatively low, so that it can be produced with structurally simple measures. For example, the storage tank can be provided by a boundary made of concrete, while heat transfer loops can be laid in the surrounding soil.

[0041] In preferred embodiments, the heat storage and exchanger comprises a valve arrangement in order to selectively guide, in a first position, a heat transfer medium through the storage tank or to connect, in a second position, the storage tank and the geothermal collector in series, wherein a controller is configured to switch the valve arrangement from the first position into the second position when a stored amount of energy in the storage tank is above an energy threshold value.

[0042] The heat storage and exchanger may include at least two or at least three additional heat exchangers.

[0043] The at least two or at least three additional heat exchangers may be arranged at different heights in the storage tank.

[0044] In corresponding embodiments, the heat storage and exchanger may realize a multi-zone heat storage. In other words, for example, heating water and domestic hot water with different temperatures can be provided by the several heat exchangers at different heights.

[0045] An embodiment as a multi-zone heat storage may be particularly advantageous for storing heat which is provided at a high temperature, i.e. as a high-temperature heat storage. The embodiment as a multi-zone heat storage can enable, for example, a temperature of at least 60° C. to be provided in the upper region, by which a formation of legionella can be avoided and a provision of domestic hot water can be enabled.

[0046] The storage tank may be configured as an ice storage.

[0047] For example, the storage tank may comprise a pressure compensation vessel. In particular, a gas volume of the pressure compensation vessel may be at least 8% of a volume of the storage tank for the thermal storage medium, for example when the thermal storage medium is in the liquid aggregate state.

[0048] Alternatively or additionally, the heat storage and exchanger may comprise a circulation device such as a circulation pump and / or an agitator, which is configured to circulate the thermal storage medium in the storage tank. The circulation device may be arranged in the thermal storage tank. The circulation device may be configured to generate a flow, in particular in the region of the heat exchanger.

[0049] The heat storage and exchanger may comprise a flow channel. The flow channel may be arranged in the thermal storage tank. The flow channel may be arranged so that the flow channel defines a direction of the stream generated by the circulation device towards the heat exchanger and / or so that the flow channel limits the flow generated by the circulation device. The flow channel may enclose at least a section of the generated flow and / or of the heat exchanger and / or of the circulation device.

[0050] The flow channel may comprise a first tube, for example an outer tube.

[0051] The first tube may enclose a section of the heat exchanger and / or a section of the generated flow and / or of the circulation device; in particular, in order to limit the generated flow to the outside and / or to define the direction of the generated flow towards the heat exchanger. The first tube may enclose at least a section of the generated flow and / or of the heat exchanger and / or of the circulation device. The first tube may be concentric with the double-pipe heat exchanger.

[0052] The flow channel may comprise a second tube, e.g. an inner tube. The second tube may limit the generated flow to the inside, in particular, in order to define the direction of the generated flow towards the heat exchanger. The second tube may be enclosed by at least a section of the generated flow and / or of the heat exchanger. The second tube may be concentric with the heat exchanger and / or with the first tube.

[0053] Embodiments for use as an ice storage, e.g. with a pressure compensation vessel, a circulation pump and / or an agitator, may be used in a particularly advantageous manner for storing thermal energy or heat at a low temperature, i.e. as a low-temperature heat storage. Corresponding embodiments may further increase the storage capacity of the heat storage and exchanger by utilizing the latent heat during the phase transition of the thermal storage medium from the liquid aggregate state to the ice. In particular, the storage capacity for cold may be increased by the ice. Furthermore, the storage tank may be arranged in the ground without a risk that the storage tank is damaged by a volume change of the thermal storage medium in the event of frost or ice formation, respectively.

[0054] The storage tank may comprise an upper lateral surface section and a lower lateral surface section.

[0055] The upper lateral surface section may comprise a stronger thermal insulation between the inner side and the outer side of the storage tank than the lower lateral surface section.

[0056] Corresponding embodiments can enable the lower region of the storage tank to be thermally coupled to an environment of the storage tank, in particular to the surrounding soil, while the upper region of the storage tank is thermally insulated. In particular, if the heat storage is configured as a multi-zone heat storage, the storage capacity may thereby be increased at a lower temperature which is associated with the lower region of the storage tank, for example for heating water. At the same time, a higher temperature which is associated with the upper region may be kept high, for example for domestic hot water. Thus, corresponding embodiments may be particularly advantageous for use as a high-temperature heat storage.

[0057] In some embodiments, the upper lateral surface section has a height which is at least half of a height of the storage tank.

[0058] In some embodiments, the lower lateral surface section has a height which is at least a fifth of the height of the storage tank.

[0059] In some embodiments, the thermal storage medium is arranged in the storage tank, and the thermal storage medium has a freezing point of at most −1° C. or of at most −2° C. in particular in embodiments for use as a low-temperature heat storage.

[0060] In corresponding embodiments, it may be ensured that, when the temperature drops below 0°, water initially freezes in an environment of the storage tank, in particular in the soil surrounding the storage tank, before the thermal storage medium freezes. Thus, latent heat of the water in the environment, in particular in the soil, can be used to further increase the thermal storage capacity of the heat storage and exchanger. In addition, the risk that the storage tank is damaged by a volume change of the thermal storage medium in the event of frost or ice formation, respectively, can be reduced, in particular at temperatures just below the freezing point. In addition, by keeping the thermal storage medium in its liquid aggregate state, the thermal conductivity of the thermal storage medium and / or the transfer of heat between the thermal storage medium and the heat exchanger (e.g. by convection) can be improved.

[0061] An expansion liquid may be arranged in the pressure compensation vessel.

[0062] The expansion liquid may have a freezing point which is lower than the freezing point of the thermal storage medium.

[0063] Corresponding embodiments can ensure that the expansion liquid is in the liquid aggregate state during freezing (or melting) of the thermal storage medium, and the pressure compensation vessel can thus compensate for the volume change during freezing (or melting) of the thermal storage medium.

[0064] The modifications which are described as being particularly advantageous for the high-temperature heat storage and those which are described as being particularly advantageous for the low-temperature heat storage may be formed on separate heat storage and exchangers, or on the same heat storage and exchanger. Typically, several heat storage and exchangers may be provided for a system, one of which may be optimized for use as a high-temperature heat storage and one as a low-temperature heat storage. This enables the optimization of the heat storage and exchangers with regard to their respective application. However, a single model of heat storage and exchanger may be provided (for example for the purpose of saving costs during development), which is configured both for use as a high-temperature heat storage and as a low-temperature heat storage.

[0065] A second section of the heat exchanger may comprise a thermal insulation to the thermal storage medium.

[0066] By thermally insulating the second section of the heat exchanger from the thermal storage medium, it may provide a stronger thermal coupling between the first fluid conduit and the second fluid conduit than between the thermal storage medium and any of the two fluid conduits. Thus, the temperatures of fluids in the two fluid conduits may be more closely matched to each other at one end of the second section than any of the temperature of the fluids in the two fluid conduits is matched to the temperature of the thermal storage medium.

[0067] For example, one of the fluid conduits may be coupled to a solar system to be cooled, and the other fluid conduit may be coupled to a cold side of a heat pump, and the second section may enable the temperature of the cooling fluid for the solar system to be lowered below the temperature of the thermal storage medium.

[0068] The second section may be arranged at an end region of the heat exchanger.

[0069] In particular, the second section may be arranged at an end region of the heat exchanger from which the first fluid conduit leads to a heat pump. By means of a respective second section, the fluid in the first fluid conduit, before it is led to the heat pump, can be heated (or cooled) more strongly than would otherwise be the case (i.e. without the corresponding second section) in the heat storage and exchanger. For example, the first fluid conduit may lead from the end region of the heat exchanger to the cold side of the heat pump, and the temperature of the first fluid conduit (or the fluid therein) in the end region may be approached to the temperature of the second fluid conduit (or the fluid therein), e.g. wherein the second fluid conduit comes from a solar system and comprises a temperature that exceeds that of the thermal storage medium.

[0070] By means of the fluid in the first fluid conduit, before it is led to the cold side of the heat pump, being heated more strongly (or, before it is led to the warm side of the heat pump, being cooled more strongly), a temperature difference between the fluids arriving at the warm and cold sides of the heat pump, respectively, i.e. between the first fluid conduit and the second fluid conduit (or the fluids therein) at the heat pump, can be minimized. Thereby, the efficiency of the heat pump can be improved.

[0071] A section of the first fluid conduit may comprise a thermal contact (e.g. a direct contact) to the thermal storage medium to transfer heat between the section of the first fluid conduit and the thermal storage medium. Alternatively or additionally, the section of the first fluid conduit may be arranged in a region of the storage tank for the thermal storage medium, in particular in an uppermost section of the region of the storage tank for the thermal storage medium.

[0072] The thermal contact of the section of the first fluid conduit to the thermal storage medium may outweigh a thermal contact of the section of the first fluid conduit to the second fluid conduit, for example in terms of magnitude or by a factor of 2 or 3 or 5, for example in terms of the respective thermal conductivities. In other words, the section of the first fluid conduit may be thermally insulated from the second fluid conduit.

[0073] In particular, a heat storage and exchanger for use as a high-temperature heat storage may comprise a corresponding section of the first fluid conduit.

[0074] Corresponding embodiments can particularly advantageously promote the input of heat from the first fluid conduit directly into the thermal storage medium. This may be advantageous in particular for a multi-zone heat storage or for a high-temperature heat storage, for example if the first fluid conduit coming from a warm side of a heat pump is configured to introduce the heat from the heat pump (i.e. from its warm side) into the multi-zone heat storage or the high-temperature heat storage. For example, the corresponding section of the first fluid conduit may be arranged in the uppermost region of the storage tank directly after the entry of the first fluid conduit into the storage tank. Thus, the fluid coming from the heat pump through the first fluid conduit may release heat to the uppermost region of the storage tank directly after entry into the storage tank, i.e. at its highest possible temperature. As a result, the temperature (e.g. of the thermal storage medium) in the uppermost region of the storage tank can be effectively maximized, and a supply of domestic hot water at a high temperature can thus be ensured.

[0075] The section of the first fluid conduit may be arranged at least partially in the thermal storage tank.

[0076] The section of the first fluid conduit may be arranged at an end region of the heat exchanger, in particular, the section of the first fluid conduit may directly adjoin the end region of the heat exchanger.

[0077] The storage tank may form a closed vessel for the thermal storage medium. Alternatively or additionally, the storage tank may be configured to receive a liquid thermal storage medium.

[0078] Corresponding embodiments may ensure that the thermal storage medium can be kept in the storage tank and thus the heat present in the thermal storage medium can be stored, for example in order to compensate for long-term or seasonal fluctuations in the energy demand and / or supply.

[0079] The thermal storage medium may be arranged in the storage tank. The thermal storage medium may be configured to provide an electrolyte for an electrochemical cell. The heat storage and exchanger may be configured to provide the thermal storage medium of the electrochemical cell in a fluid-coupled manner.

[0080] A second aspect relates to a use of the above-described heat storage and exchanger as an underground heat storage tank.

[0081] The second aspect may comprise the use of the above-described heat storage and exchanger as an underground heat storage tank for cooling a photovoltaic system. Alternatively or additionally, the second aspect may comprise the use of the above-described heat storage and exchanger as an underground heat storage tank for absorbing heat during an evaporation process of a coolant of a heat pump.

[0082] The second aspect may comprise the use of the above-described heat storage and exchanger as an underground heat storage tank for storing condensation heat of a refrigerant of a heat pump.

[0083] A third aspect relates to a use of the above-described heat storage and exchanger as a counterflow heat exchanger.

[0084] The counterflow heat exchanger may in particular be used for heat exchange between a refrigerant of a heat pump and a liquid heat conducting medium, wherein the liquid heat conducting medium thermally couples the first or the second fluid conduit to a photovoltaic system.

[0085] According to a fourth aspect, a system includes a heat storage and exchanger as described above, and at least one controller. The at least one controller is configured to control a fluid flow through the first fluid conduit in dependence on a first parameter, wherein the first parameter is associated with an availability of electrical power.

[0086] The at least one controller may be configured to output a control signal for a heat pump in dependence on the first parameter.

[0087] Corresponding embodiments can enable the operation of the heat pump at a high availability of electrical power, for example if a photovoltaic system produces a high electrical power, for example relative to its peak power, or if the photovoltaic system produces an excess of electrical power, for example in relation to a consumption which is associated with a building. In this situation, the high or excess electrical power can be stored by means of the heat pump as thermal energy in the heat storage and exchanger in order to be available for times of low availability of heat or energy. Thus, a demand for heat or energy can be covered in times of low availability without having to resort to an additional (for example expensive or limitedly available) energy source, such as for example natural gas. In particular, the thermal energy can be stored at a low temperature, and the temperature can be raised to a requested temperature level at a later time with the aid of a heat pump. As a result of the low storage temperature, heat can be made usable at a correspondingly low temperature (for example from photothermia under otherwise unfavorable conditions). In addition, losses in the storing can be reduced.

[0088] The heat exchanger may comprise a double-pipe heat exchanger.

[0089] The first fluid conduit may comprise an inner pipe of the double-pipe heat exchanger.

[0090] The first fluid conduit may be configured to be coupled to the heat pump, in particular the first fluid conduit may be coupled to the heat pump.

[0091] The first parameter may be associated with an electrical power provided by a photovoltaic system.

[0092] The at least one controller may comprise or be at least one electrical controller, in particular at least one electrical controller configured to receive and / or output electrical control signals.

[0093] In some embodiments, the at least one controller is a purely electrical controller, in particular without a mechanical device such as a valve or a pump.

[0094] In other embodiments, the at least one controller comprises at least one mechanical device configured to control a fluid flow, such as a valve or a pump. In particular, the at least one controller may comprise a plurality or all of the mechanical devices for controlling the fluid flow.

[0095] The at least one controller may further be configured to control a fluid flow through the second fluid conduit in dependence on a second parameter.

[0096] The second parameter may be associated with a first temperature difference.

[0097] In corresponding embodiments, the controller may enable temperature control (i.e. heating or cooling) of a component connected to the second fluid conduit. For this purpose, the fluid flow through the second fluid conduit can be switched on when the second parameter indicates a temperature or a temperature difference within a target range suitable for temperature control. The fluid flow through the second fluid conduit can be switched off when the second parameter is outside the target range. The component to be temperature controlled may be a solar system.

[0098] In the context of this description, a solar system may comprise a photovoltaic system and / or a photothermal system. In particular, a solar system may comprise a combined solar and photothermal system.

[0099] A first temperature of the first temperature difference may be associated with the storage tank and / or the thermal storage medium.

[0100] A second temperature of the first temperature difference may be associated with a solar system and / or associated with a device that is thermally coupled to the second fluid conduit. In particular, the solar system may comprise the photovoltaic system.

[0101] The system may be configured to selectively couple the storage tank and / or the thermal storage medium to a geothermal collector.

[0102] The selective coupling may relate to a coupling whose coupling strength, in particular thermal coupling strength, is controllable, in particular by controlling a fluid flow, for example by means of a pump or a valve.

[0103] The at least one controller may be configured to selectively couple the storage tank and / or the thermal storage medium to the geothermal collector in dependence on a third parameter.

[0104] The third parameter may be associated with a second temperature difference.

[0105] A first temperature of the second temperature difference may be associated with the storage tank and / or the thermal storage medium.

[0106] A second temperature of the second temperature difference may be associated with the geothermal collector.

[0107] Corresponding embodiments can enable to selectively transfer heat from the storage tank (or the thermal storage medium) to the geothermal collector or extract heat from the geothermal collector. Thus, the geothermal collector can on the one hand be used as an extension of the heat storage. On the other hand, especially in the case of a change, in particular an increase, in the outside temperature, the heat thereby available can be introduced into the storage tank (or the thermal storage medium) by means of the geothermal collector and can this way be used.

[0108] The system may further comprise a second heat storage and exchanger. The second heat storage and exchanger may comprise a first fluid conduit, a second fluid conduit, and a storage tank. The storage tank may be configured to receive a thermal storage medium.

[0109] The second heat storage and exchanger may be configured to enable a transfer of heat between the first fluid conduit and the thermal storage medium and between the second fluid conduit and the thermal storage medium.

[0110] The at least one controller may be configured to control a fluid flow through the first fluid conduit of the second heat storage and exchanger together with the fluid flow through the first fluid conduit of the heat storage and exchanger.

[0111] Corresponding embodiments may provide an optimized system for long-term storing of heat or cold in combination with a heat pump. For this purpose, the first fluid conduit of the heat storage and exchanger can be coupled to one, e.g. cold, side of the heat pump, and the first fluid conduit of the second heat storage and exchanger can be coupled to a second, for example warm, side of the heat pump.

[0112] During the generation of heat, a heat pump system generates the same amount of cold energy. During use as a cooling system, i.e. during the generation of cold, a heat pump system generates the same amount of heat energy. During conventional heat generation (conventional use as an air conditioning system), the cold energy (heat energy) is released as a waste product to the environment, e.g. to air or to groundwater.

[0113] Many buildings require, in addition to the generation of heat, e.g. for heating or domestic hot water, also a cooling system, e.g. for air conditioning / building cooling or as photovoltaic cooling. However, the demand for heat (e.g. in winter) and cold (e.g. for cooling in summer) often occur at different times (e.g. seasonally). By using the two heat storage and exchangers and their combination in the system, the cold generated during the generation of heat (or the heat generated during the use as a cooling system) is stored and provided for use as required.

[0114] By using the cold energy during the generation of heat and the heat energy during the use as a cooling system, the energy efficiency can be doubled compared to the conventional solution. This dual use can take place both locally, applying suitable storage media, and also at district-level by feeding into heating and cold networks.

[0115] By jointly controlling the fluid flows through the two first fluid conduits, a heat transfer from the heat storage and exchanger to the second heat storage and exchanger can be enabled in such embodiments. In other words, the thermal storage medium of the heat storage and exchanger is cooled, the thermal storage medium of the second heat storage and exchanger is heated (or vice versa). With a corresponding design of the heat storage and exchangers (for example their volumes), this can enable a storing of the heat or cold over months or seasons.

[0116] The storage tank (or the thermal storage medium contained therein) and / or the geothermal collector thermally coupled to the heat storage and exchanger can be configured as an energy-storing component or provide an energy-storing component of the heat storage and exchanger, or can be referred to as such, respectively.

[0117] In other words, the heat storage and exchanger may comprise an energy-storing component. The energy-storing component may comprise or be the storage tank and / or the geothermal collector thermally coupled to the heat storage and exchanger.

[0118] In yet other words, the storage tank may be the energy-storing component of the heat storage and exchanger, or the geothermal collector thermally coupled to the heat storage and exchanger may be the energy-storing component of the heat storage and exchanger, or both may be (i.e. together) the energy-storing component of the heat storage and exchanger.

[0119] A geothermal collector (for example a further geothermal collector or a geothermal collector spatially separate from the geothermal collector thermally coupled to the heat storage and exchanger) may be thermally coupled to the second heat storage and exchanger.

[0120] The second heat storage and exchanger may comprise an energy-storing component, for example with properties which are similar to the above-described properties of the energy-storing component of the heat storage and exchanger, but with respect to the second heat storage and exchanger instead of the heat storage and exchanger.

[0121] In some embodiments, a thermally insulating dividing wall delimits ground regions, in particular adjacent ground regions, from each other. The thermally insulating dividing wall may be arranged at least partially, in particular for the most part (e.g. according to its height extension), below a ground surface. The ground regions delimited from each other may each be associated with a geothermal collector. In particular, one of the delimited ground regions may be associated with the geothermal collector which is thermally coupled to the (first) heat storage and exchanger, and another of the delimited ground regions may be associated with the geothermal collector which is thermally coupled to the second heat storage and exchanger.

[0122] In preferred embodiments, the energy-storing component of the first heat storage and exchanger (in particular the geothermal collector thereof) is adjacent to the energy-storing component of the second heat storage and exchanger (in particular the geothermal collector thereof) and is delimited laterally from the energy-storing component of the second heat storage and exchanger (in particular the geothermal collector thereof) by a thermally insulating dividing wall embedded in the soil.

[0123] For example, adjacent ground sections may each be equipped with geothermal collectors, and the thermally insulating dividing wall may be embedded in the floor between the heat transfer loops of the geothermal collector which is thermally coupled to the first heat storage and exchanger and the geothermal collector which is thermally coupled to the second heat storage and exchanger, so that different temperatures can be provided in the energy-storing component of the first heat storage and exchanger (in particular the geothermal collector thereof) and the energy-storing component of the second heat storage and exchanger (in particular the geothermal collector thereof).

[0124] In preferred embodiments, the energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof) is separated from the surrounding soil by the thermally insulating dividing wall encircling the energy-storing component laterally.

[0125] A laterally encircling insulating dividing wall may allow a higher temperature level in the energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof) to be maintained for a longer time and / or with lower energy losses and thus to provide a seasonal storing of thermal energy in the energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof) at an increased storage temperature. The thermally insulating dividing wall may extend vertically over the lower end of the energy-storing component of the heat storage and exchanger (in particular over the lower end of the geothermal collector thereof) downwards into the soil in order to define an insulated section of the energy-storing component (in particular the geothermal collector thereof). The insulated section may be open downwards in order to exploit the thermal capacity of the underlying soil.

[0126] The energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof) may be adjacent to the energy-storing component of the second heat storage and exchanger (in particular the geothermal collector thereof) and be separated therefrom by the thermally insulating dividing wall. The thermally insulating dividing wall should have a reduced thermal conductivity with respect to the soil, in particular a thermal conductivity of less than 1 W / (m*K), preferably less than 0.5 W / (m*K), more preferably less than 0.2 W / (m*K). The insulation may be a perimeter insulation, which may be provided by plates in the soil, for example made of Styrodur, and / or may comprise sections of pourable insulation material, such as foam glass granules. In some embodiments, the thermally insulating dividing wall is separated from the energy-storing components on both sides by the soil.

[0127] In some embodiments, the system further comprises an upper dividing wall, which forms an upper boundary of the energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof) in order to thermally insulate the energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof) in the vertical direction. For example, the upper dividing wall may be arranged below a floor panel of a building in order to reduce heat losses of the energy-storing component into the building.

[0128] In preferred embodiments, the system further comprises a lower dividing wall, which forms a lower boundary of the energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof) in order to thermally insulate the energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof) in the vertical direction with respect to the underlying soil.

[0129] The lower dividing wall may improve an insulation of the energy-storing component of the heat storage and exchanger (in particular the geothermal collector thereof), so that the temperature level thereof can be maintained for a longer time and / or with lower energy losses.

[0130] The system may comprise the heat pump.

[0131] The fluid flow through the first fluid conduit of the heat storage and exchanger may be configured to thermally couple the heat storage and exchanger to one side, e.g. a warm or cold side, of the heat pump.

[0132] The fluid flow through the first fluid conduit of the second heat storage and exchanger may be configured to thermally couple the second heat storage and exchanger to one side, e.g. a complementary cold or warm side, of the heat pump.

[0133] The heat pump may be configured to provide a power of at least 3 kW or of at least 5 kW.

[0134] The system may comprise a solar system.

[0135] The heat storage and exchanger of the system may comprise at least one additional heat exchanger, wherein one of the at least one additional heat exchangers is configured to thermally couple the solar system to the storage tank and / or to the thermal storage medium of the heat storage and exchanger, in particular in series with a geothermal collector.

[0136] An additional heat exchanger of the second heat storage and exchanger may be configured to thermally couple the solar system to the storage tank and / or to the thermal storage medium of the second heat storage and exchanger.

[0137] The second heat storage and exchanger may comprise one or all of the features described above in connection with the heat storage and exchanger of the first aspect.

[0138] In a fifth aspect, a system includes a first heat storage and exchanger, a second heat storage and exchanger, a heat pump, and a controller. The first heat storage and exchanger includes a first fluid conduit, a second fluid conduit, a heat exchanger, and a storage tank. The heat exchanger is configured to transfer heat between the first fluid conduit and the second fluid conduit. The storage tank is configured to receive a thermal storage medium. At least a section of the heat exchanger is arranged in the storage tank to enable a transfer of heat between the heat exchanger and the thermal storage medium. The first heat storage and exchanger has a volume for its thermal storage medium of at least 2 m2 and is arranged at least partially underground. The second heat storage and exchanger includes a first fluid conduit, a second fluid conduit, and a storage tank configured to receive a thermal storage medium. The second heat storage and exchanger is configured to enable a transfer of heat between its first fluid conduit and its thermal storage medium and between its second fluid conduit and its thermal storage medium. The heat pump is configured to provide a power of at least 5 kW. A fluid flow through the first fluid conduit of one of the first heat storage and exchanger and the second heat storage and exchanger is configured to thermally couple the first heat storage and exchanger to a cold side of the heat pump. The fluid flow through the first fluid conduit of the other heat storage and exchanger is configured to thermally couple the other heat storage and exchanger to a warm side of the heat pump. The controller is configured to control an operating state of the heat pump, the fluid flow through the first fluid conduit of the first heat storage, and the fluid flow through the first fluid conduit of the second heat storage together in dependence on a first parameter, wherein the first parameter is associated with an electrical power provided by a photovoltaic system. The second fluid conduit of at least one of the first heat storage and exchanger and the second heat storage and exchanger is coupled to a solar system.

[0139] The other heat storage and exchanger may relate to the heat storage and exchanger or to the second heat storage and exchanger; in particular to the one of the two in which the fluid flow through its first fluid conduit is not configured to thermally couple it to the cold side of the heat pump.

[0140] The thermal storage medium of the second heat storage and exchanger may be arranged in the storage tank of the second heat storage and exchanger. The thermal storage medium arranged in the storage tank of the second heat storage and exchanger may be configured to provide a second electrolyte for the electrochemical cell. The second heat storage and exchanger may be configured to provide the thermal storage medium of the electrochemical cell in a fluid-coupled manner.

[0141] The system may comprise the electrochemical cell, wherein the thermal storage medium of the first heat storage and exchanger and the thermal storage medium of the second heat storage and exchanger are fluidly coupled to the electrochemical cell; in particular, wherein the thermal storage medium of the first heat storage and exchanger and the thermal storage medium of the second heat storage and exchanger are fluidly coupled to different half-cells of the electrochemical cell.

[0142] According to a sixth aspect, a method of generating an underground heat storage comprises arranging at least a portion of a heat storage and exchanger in the ground. The heat storage and exchanger includes a first fluid conduit, a second fluid conduit, a heat exchanger, and a storage tank. The heat exchanger is configured to transfer heat between the first fluid conduit and the second fluid conduit. The storage tank is configured to receive a thermal storage medium. At least a section of the heat exchanger is arranged in the storage tank to enable a transfer of heat between the heat exchanger and the thermal storage medium.

[0143] The method may further comprise thermally coupling the heat storage and exchanger to the ground.

[0144] The method may further comprise configuring the heat exchanger as a counterflow heat exchanger.

[0145] The method may further comprise coupling the first fluid conduit to a heat pump.

[0146] The method may further comprise thermally coupling the heat storage and exchanger to a first heating network, in particular to a first local heating network, to selectively store heat or cold from the heat storage and exchanger to the local heating network or to extract heat or cold from the local heating network to the heat storage and exchanger. In particular, the heat storage and exchanger may be coupled in series to the first heating network (in particular in series to the first local heating network) with at least one of the geothermal collector and the soil.

[0147] The method may further comprise coupling a first fluid conduit of a second heat storage and exchanger to the heat pump.

[0148] The second heat storage and exchanger may comprise one or all of the features described above in connection with the second heat storage and exchanger of the fourth aspect.

[0149] The method may further comprise coupling the second heat storage and exchanger to a second heating network, in particular to a second local heating network, in particular wherein the second (local) heating network has a lower temperature on average than the first (local) heating network. In particular, the second heat storage and exchanger may be coupled to the second heating network (in particular to the second local heating network) in series with its geothermal collector and / or with the soil surrounding it.

[0150] For example, the first (local) heating network may be a high-temperature (local) heating network, and the second (local) heating network may be a low-temperature (local) heating network (in other words, a (local) cold network).

[0151] A thermal insulation, in particular a thermally insulating dividing wall, may be arranged between a region of the first (local) heating network (e.g. the high-temperature (local) heating network) and a region of the second (local) heating network (e.g. the low-temperature (local) heating network or the (local) cold network). In particular, the thermal insulation may be arranged at least partially underground or the thermally insulating dividing wall may be an underground thermally insulating dividing wall. For example, the thermal insulation or the thermally insulating dividing wall may be arranged between a geothermal collector (or an underground fluid conduit) of the first (local) heating network (e.g. the high-temperature (local) heating network) and a geothermal collector (or an underground fluid conduit) of the second (local) heating network (e.g. the low-temperature (local) heating network or the (local) cold network).

[0152] The method may further comprise coupling the second fluid conduit to a solar system.

[0153] The method may further comprise configuring a controller to receive or determine a first parameter, wherein the first parameter is associated with an availability of electrical power.

[0154] The method may further comprise configuring the at least one controller to control a fluid flow through the first fluid conduit in dependence on the first parameter.

[0155] The heat storage and exchanger may include at least one additional heat exchanger.

[0156] The method may further comprise coupling a heat exchanger of the at least one additional heat exchanger to a geothermal collector.

[0157] The at least one additional heat exchanger may comprise one or all of the features of the at least one additional heat exchanger described above in connection with the heat storage and exchanger of the first aspect.

[0158] In embodiments in which the method comprises coupling the first fluid conduit to a heat pump, the method may further comprise coupling a first fluid conduit of a second heat storage and exchanger to the heat pump. In particular, in corresponding embodiments, the first fluid conduit of the heat storage and exchanger may be coupled to a cold side of the heat pump and the first fluid conduit of the second heat storage and exchanger may be coupled to a warm side of the heat pump. Alternatively, the first fluid conduit of the heat storage and exchanger may be coupled to the warm side of the heat pump and the first fluid conduit of the heat storage and exchanger may be coupled to the warm side of the heat pump.

[0159] The method may further comprise performing one or all of the method steps having a relation to the heat storage and exchanger correspondingly on the second heat storage and exchanger.

[0160] According to a seventh aspect, a method of operating a system comprising a heat storage and exchanger comprises at least two modes of operation, and the method comprises selectively executing one of the at least two modes of operation. The first mode of operation comprises operating the heat pump at a first heat pump power and generating a fluid flow through the first fluid conduit to transfer heat between the heat pump and the thermal storage medium. The second mode of operation comprises operating the heat pump at a second heat pump power that is at most a quarter of the first heat pump power and generating a stronger fluid flow through the second fluid conduit than through the first fluid conduit to transfer heat via the second fluid conduit. The heat storage and exchanger may comprise one or all of the features of the heat storage and exchanger of the first aspect.

[0161] In some embodiments, selectively executing one of the at least two modes of operation comprises automatically selecting between the first and second modes of operation based on a first parameter. In particular, the first parameter may be associated with an availability of electrical power.

[0162] The method may comprise selectively guiding the fluid flow through the second fluid conduit to a solar system, to a geothermal collector or to the solar system and the geothermal collector.

[0163] The method may further comprise, in the first and / or second mode of operation, controlling a strength of the fluid flow through the second fluid conduit in dependence on a first temperature difference. In particular, a first temperature of the first temperature difference may be associated with the storage tank and / or the thermal storage medium. In particular, a second temperature of the first temperature difference may be associated with a solar system.

[0164] The method may further comprise selectively extracting heat from the heat storage and exchanger or a geothermal collector coupled to the heat storage and exchanger, in particular in dependence on a temperature associated with the storage tank and / or the thermal storage medium; and / or in dependence on a temperature associated with the geothermal collector.

[0165] The method may further comprise controlling a thermal coupling between the geothermal collector and the storage tank and / or the thermal storage medium in dependence on a second temperature difference. In particular, a first temperature of the second temperature difference may be associated with the storage tank and / or the thermal storage medium; and / or a second temperature of the second temperature difference may be associated with the geothermal collector.

[0166] The system may comprise a second heat storage and exchanger.

[0167] The second heat storage and exchanger may comprise one or all of the features described above in connection with the second heat storage and exchanger of the fourth aspect.

[0168] The method may further comprise performing the method steps having a relation to the heat storage and exchanger correspondingly on the second heat storage and exchanger. In particular, in corresponding embodiments, the first fluid conduit of the heat storage and exchanger may be coupled to a cold side of the heat pump; and the first fluid conduit of the second heat storage and exchanger may be coupled to a warm side of the heat pump. Alternatively, the first fluid conduit of the first heat storage and exchanger may be coupled to the warm side of the heat pump and the first fluid conduit of the second heat storage and exchanger may be coupled to the warm side of the heat pump.

[0169] According to an eighth aspect, a computer program is configured to cause an electronic control system to carry out the method according to the seventh aspect.

[0170] According to a further aspect, a local heating network includes a first heat storage and exchanger, a second heat storage and exchanger, and a geothermal collector.

[0171] The first heat storage and exchanger is a heat storage and exchanger as described above in the context of the first aspect. Alternatively, the local heating network includes a system as described above, and the first heat storage and exchanger is the heat storage and exchanger of the system.

[0172] The second heat storage and exchanger is a heat storage and exchanger as described above in the context of the first aspect. Alternatively, the local heating network includes a system as described above, and the first heat storage and exchanger is the heat storage and exchanger of the system. The second heat storage and exchanger is spatially separate from the first heat storage and exchanger, for example by at least 50 m or by at least 100 m or by at least 200 m.

[0173] The geothermal collector is thermally coupled to the first heat storage and exchanger and to the second heat storage and exchanger and configured to store heat or cold to a surrounding soil and to extract at least a portion of the stored heat or cold from the soil at a later time.

[0174] The local heating network may further comprise a conduit configured to thermally couple the first heat storage and exchanger and the second heat storage and exchanger to each other. A first portion of the conduit may comprise thermal insulation. A second portion of the conduit, to form the geothermal collector, may comprise less or no thermal insulation.

[0175] According to a further aspect, a local heating network system comprises a local heating network as described above, and further comprising a second local heating network.

[0176] The second local heating network comprises: a first low temperature heat storage, a second low temperature heat storage, and a second geothermal collector.

[0177] The first low temperature heat storage is a heat storage and exchanger as described above in the context of the first aspect. Alternatively, the local heating network includes a system as described above, and the first low temperature heat storage is the second heat storage and exchanger of the system.

[0178] The thermal storage medium of the first low temperature heat storage has a lower temperature than the thermal storage medium of the first heat storage and exchanger.

[0179] The second low temperature heat storage is a heat storage and exchanger as described above in the context of the first aspect. Alternatively, the local heating network includes a system as described above, and the first low temperature heat storage is the second heat storage and exchanger of the system.

[0180] The second low temperature heat storage is spatially separate from the first low temperature heat storage, for example by at least 50 m or by at least 100 m or by at least 200 m.

[0181] The thermal storage medium of the second low temperature heat storage has a lower temperature than the thermal storage medium of the second heat storage and exchanger.

[0182] The second geothermal collector is thermally coupled to the first low temperature heat storage and to the second low temperature heat storage and configured to store second heat or cold to a surrounding soil and to extract at least a portion of the stored second heat or cold from the soil at a later time.

[0183] In some embodiments, the local heating network system further comprises a thermally insulating dividing wall configured to thermally insulate a region of the local heating network from a region of the second local heating network. In particular, the thermally insulating dividing wall may be arranged at least partially underground.BRIEF DESCRIPTION OF THE FIGURES

[0184] The invention is explained in more detail below with reference to exemplary embodiments and with reference to the attached drawings. In the figures, in schematic representation:

[0185] FIG. 1 shows a heat storage and exchanger according to one example;

[0186] FIG. 2a shows a heat storage and exchanger according to a further example;

[0187] FIG. 2b shows a heat storage and exchanger according to a further example;

[0188] FIG. 3 shows a heat storage and exchanger according to a further example;

[0189] FIG. 4 shows a system with a heat storage and exchanger according to one example;

[0190] FIG. 5a shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to one example;

[0191] FIG. 5b shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to a further example;

[0192] FIG. 5c shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to a further example;

[0193] FIG. 5d shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to a further example;

[0194] FIG. 5e shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to a further example;

[0195] FIG. 5f shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to a further example;

[0196] FIG. 5g shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to a further example;

[0197] FIG. 5h shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to a further example;

[0198] FIG. 5i shows a system with a heat storage and exchanger and an operating mode of a method of operating the system according to a further example;

[0199] FIGS. 6a-6e show a system with a heat storage and exchanger coupled to a local heating network;

[0200] FIG. 7a shows a heat storage and exchanger according to a further example;

[0201] FIG. 7b shows a heat storage and exchanger according to a further example;

[0202] FIG. 7c shows a heat storage and exchanger according to a further example;

[0203] FIG. 7d shows a heat storage and exchanger according to a further example;

[0204] FIG. 7e shows a heat storage and exchanger according to a further example;

[0205] FIG. 8 shows a heat storage and exchanger according to a further example;

[0206] FIG. 9a shows a local heating network with an electrochemical cell according to an example; and

[0207] FIG. 9b shows a local heating network system with an electrochemical cell according to an example.DESCRIPTION OF THE FIGURES

[0208] FIG. 1 shows a heat storage and exchanger 100 according to a first exemplary embodiment.

[0209] The heat storage and exchanger 100 includes a storage tank 106 for a thermal storage medium 108, and a heat exchanger 104 which is arranged partially in the storage tank 106.

[0210] Due to the integrated heat exchanger 104, the heat storage and exchanger 100 is in particular also suitable for retrofitting existing systems.

[0211] The storage tank 106 is dimensioned sufficiently large to receive a sufficiently large amount (e.g. volume) of the thermal storage medium 108 that it provides a thermal capacity to cover a heat demand of a building over a longer period of time, such as several days, weeks or months. For example, the storage tank 106 may be configured for the heat demand of a single-family house, and its volume may be approximately 2 m2, 5 m2, 10 m2, 15 m2 or 20 m2 depending on the size of the single-family house. In alternative embodiments, a larger storage tank 106 or a plurality of storage tanks 106 is provided for a larger individual building or a building complex.

[0212] Thus, the storage tank 106 with the thermal storage medium 108 contained therein, using energy in the form of heat which is stored in times of good availability (during day, summer, or in periods of warm and / or sunny weather), allows the demand of a building for heat to be covered completely or partially in a period of poor availability (during night, winter, or in periods of cold and / or low-sun weather).

[0213] The storage tank 106 is configured to be introduced into the soil. Accordingly, its wall consists of an opaque, liquid-tight and preferably corrosion-resistant material such as steel. Alternatively or additionally, a wall made of concrete is provided in order to mechanically reinforce the wall.

[0214] The storage tank 106 provides a space for the thermal storage medium 108. For example, the storage tank 106 provides a target filling height 116 for the thermal storage medium 108.

[0215] Fluid conduits 102a, 102b extend to above the space of the storage tank 106 for the thermal storage medium 108, i.e. to above the target filling height 116. In other words, sections of the fluid conduits 102a, 102b which are arranged outside the storage tank 106 (e.g. supply / discharge lines or connection elements of the fluid conduits 102a, 102b) are higher in the vertical direction than the space of the storage tank 106 for the storage medium 108 or higher than the target filling height 116. Thus, the fluid conduits 102a, 102b are accessible from above and also accessible from above ground when the storage tank 106 is arranged underground.

[0216] The underground arrangement does not necessarily mean that the entire storage tank 106 is arranged below the ground surface. In some embodiments, only the lower portion of the storage tank 106 is arranged below the ground surface, for example the lowermost 60%, 70%, 80%, 90% or 95% of its height extension. Preferably, the upper side of the storage tank 106 terminates with the ground surface or is arranged slightly above the ground surface so that the supply / discharge lines or connection elements of the fluid conduits 102a, 102b are accessible from above ground.

[0217] In the embodiment shown, the sections of the fluid conduits 102a, 102b which are arranged outside the storage tank 106 (e.g. supply / discharge lines or connection elements of the fluid conduits 102a, 102b) are higher in the vertical direction than the entire storage tank 106.

[0218] Due to its dimensioning (at least 1 m3, in particular 2 m2 for the thermal storage medium) and material composition (opaque, liquid-tight and preferably corrosion-resistant), the storage tank 106 is also referred to below as a cistern storage 106.

[0219] In the storage tank 106 of FIG. 1, the cross-sectional area in horizontal planes at different heights is always the same (i.e. along the entire height extension of the storage tank 106). In alternative embodiments, the cross-sectional area decreases towards the top. In any case, the cross-sectional area does not increase significantly towards the top.

[0220] As a result, the heat storage and exchanger 100 can be lowered comfortably into a pit, in particular for an underground arrangement.

[0221] In the illustrated storage tank, the cross-sectional area is round, in alternative embodiments elliptical. The absence of corners, projections or bulges in the cross-sectional area further facilitates the lowering into the pit.

[0222] By means of the underground arrangement, the heat storage and exchanger 100 minimizes its space requirement (i.e. the demand for footprint) in the building to be supplied with heat or on the property in which it is installed. The heat storage and exchanger 100 may, for example, pose a retrofitting component for an existing system as an underground heat storage and exchanger 100.

[0223] The heat exchanger 104 of the embodiment of FIG. 1 is configured as a double-pipe heat exchanger. The second fluid conduit 102b is arranged coaxially around the first fluid conduit 102a. The first fluid conduit 102a and the second fluid conduit 102b are thus in thermal contact via a common wall. In alternative embodiments, the heat exchanger 104 is a plate heat exchanger or a tube bundle heat exchanger or a multiple-pipe heat exchanger with more than two coaxial conduits, wherein the outermost two conduits serve as first fluid conduit 102a and second fluid conduit 102b.

[0224] The arrangement of the heat exchanger 104 in the storage tank 106 enables a large pipe length of the (in particular double-pipe) heat exchanger, and thus an effective heat transfer between the first and second fluid conduit 102, 102b. In particular, the space available in the storage tank 106 is greater than in a conventional arrangement of a heat exchanger in a heat pump. Instead of a double-pipe heat exchanger, a multiple-pipe heat exchanger (i.e., with more than two conduits which are arranged coaxially in thermal contact with one another), a plate heat exchanger or a tube bundle heat exchanger may be installed in order to likewise benefit from the greater space available. In the exemplary embodiment shown, the double-pipe heat exchanger 104 is spiral-shaped with a height of 2 m and a diameter of 0.5 m, but diameters of 1 m, 2 m, 3 m or 4 m are possible (adapted to the annual energy needed by the building to be supplied).

[0225] A first section 144 of the heat exchanger 104 is arranged below the target filling height 116 (i.e., is arranged in the area of the storage tank 106 for the thermal storage medium 108) and is, via its outer wall which at the same time forms the outer wall of the second fluid conduit 102b, in thermal contact with the space of the storage tank 106 for the thermal storage medium 108. The space of the storage tank 106 for the thermal storage medium 108 surrounds the second fluid conduit 102b and, in embodiments with a double-pipe heat exchanger, the first fluid conduit 102a. In other words, the arrangement of the heat exchanger 104 (in particular of its first section 144) in the storage tank 106 (in particular in the space of the storage tank 106 for the thermal storage medium 108) forms a triple heat exchanger composed of first fluid conduit 102a, second fluid conduit 102b and storage tank 106 (in particular the space of the storage tank 106 for the thermal storage medium 108 or below the target filling height 116). This arrangement enables the exchange of heat between a fluid in the first fluid conduit 102a, a fluid in the second fluid conduit 102b and the thermal storage medium 108.

[0226] Also for the heat transfer between the second fluid conduit 102b (and indirectly the first fluid conduit 102a) and the thermal storage medium 108, the arrangement of the heat exchanger 104 in the storage tank 106 enables an effective heat transfer, as described above in connection with the heat transfer between the first fluid conduit 102a and the second fluid conduit 102b.

[0227] The heat exchanger 104 extends upwards through the space of the storage tank 106 for the thermal storage medium 108 to above the target filling height 116 of the storage tank 106 for the thermal storage medium 108. Thus, a first section 144 (e.g. below the target filling height 116 of the storage tank 106 for the thermal storage medium 108) of the heat exchanger 104 is in thermal contact with the thermal storage medium 108, whereas a second section 138 (e.g. above the target filling height 116 of the storage tank 106 for the thermal storage medium 108) of the heat exchanger 104 is not in thermal contact with the thermal storage medium 108 (or the space of the storage tank 106 provided therefor), i.e. is spaced apart therefrom or is insulated therefrom by air. The first section 144 corresponds to the central region of the heat exchanger 144, the second section 138 corresponds to the two end regions 138 of the heat exchanger 104.

[0228] The thermal conductivity between the first fluid conduit 102a and the second fluid conduit 102b can be considered as a reference for the presence or absence of the thermal contact between a section of the heat exchanger 104 and the thermal storage medium 108. If the thermal conductivity between the section of the heat exchanger 104 and the thermal storage medium 108 (e.g. per length) is lower (e.g. simply lower, or lower by a factor of 2, 3, 5 or 10) than the thermal conductivity between the first fluid conduit 102a and the second fluid conduit 102b, then a thermal contact is not present. As a result, the temperatures of fluids in the first fluid conduit 102a and the second fluid conduit 102b are more closely matched to each other than to the temperature of the thermal storage medium 108 (e.g. than any of the first fluid conduit 102a and the second fluid conduit 102b is matched to the temperature of the thermal storage medium 108).

[0229] Since, in the illustrated embodiment, the heat exchanger 104 is in thermal contact with the thermal storage medium 108 in its central region 144 (i.e. in its first section 144), the temperature of fluids flowing through the fluid conduits 102a, 102b is largely matched to the temperature of the thermal storage medium 108 there. In contrast, in at least one end region 138 (i.e. in its second section 138), the heat exchanger 104 is not in thermal contact with the thermal storage medium 108. Consequently, the temperature of a fluid flowing through one of the fluid conduits 102a, 102b, after flowing through the central region 144 of the heat exchanger 104, is approached to the temperature of the fluid in the other fluid conduit 102a, 102b in this end region 138.

[0230] Preferably, the heat exchanger 104 is operated as a counterflow heat exchanger. Thus, in the end region 138, the temperature of the outflowing fluid of the one fluid conduit 102a, 102b is matched to the temperature of the inflowing fluid of the other fluid conduit 102a, 102b. Typically, the temperature spread between these fluids is greater than the temperature difference of the outflowing fluid to the thermal storage medium 108. Thus, the outflowing fluid is cooled or heated more strongly in the end region 138 of the heat exchanger 104 without thermal contact to the thermal storage medium 108 than would be the case if the thermal contact of the heat exchanger 104 to the thermal storage medium 108 were present along the entire length of the heat exchanger 104. In exemplary embodiments, the outflowing fluid from the second fluid conduit102b is conducted to a photovoltaic system for cooling, whereas the inflowing fluid into the first fluid conduit 102a, coming from a cold side of a heat pump, provides the required cold. In such embodiments, a lower temperature of the outflowing fluid from the second fluid conduit 102b and thus an improved cooling of the photovoltaic system is achieved by the end region 138 of the heat exchanger 104.

[0231] The extent of the temperature matching of the fluid conduits 102a, 102b (or of the fluids contained therein) in the end region 138 of the heat exchanger may be controlled by controlling the flow rate of at least one of the fluids (in particular, of both fluids) in its fluid conduit 102a, 102b (in particular, in the two fluid conduits 102a, 102b). A significant temperature matching between the fluid conduits 102a, 102b (or the fluids contained therein) is avoided by a high flow rate. The outflowing fluid substantially has the temperature of the thermal storage medium 108. A strong temperature matching between the fluid conduits 102a, 102b (or the fluids contained therein) is achieved using a low flow rate, and the outflowing fluid substantially has the temperature of the other fluid conduit (or of the fluid contained therein). Preferably, a temperature sensor for detecting the temperature of the outflowing fluid is provided, and the flow rate of one of the fluids (or of the two fluids) through the associated fluid conduit(s) 102a, 102b is regulated with respect to the temperature detected by the temperature sensor (in particular, in order to reach a predetermined target temperature).

[0232] The thermal storage medium 108 consists for the most part (for example in terms of its volume) of water. In addition, an anti-freeze agent is contained so that the freezing point of the thermal storage medium 108 is below that of water, for example at at most −1° C. or at most −2° C., for low-temperature applications also below −20° C. or −35° C. In alternative embodiments, in particular for use as a high-temperature heat storage, thermal storage media 108 are used which have a melting point in the range of 10° C. to 70° C. (e.g. 10° C., 20° C. or 30° C.), such as for example paraffins. The thermal capacity of the storage medium 108 can thereby also be increased by utilizing its latent heat at the phase transition when used as a high-temperature heat storage.

[0233] In some embodiments, the wall of the storage tank 106 enables a thermal coupling of the thermal storage medium 108 to a medium surrounding the thermal storage tank 106. Specifically, the storage tank 106 is arranged in the soil which forms the surrounding medium.

[0234] Due to the anti-freeze agent contained in the thermal storage medium 108 and its freezing point below that of water, it is ensured that, when the temperature drops (in particular below the freezing point of water), water initially freezes in the surrounding medium before the thermal storage medium 108 freezes. The thermal storage medium 108 is thus effectively protected from freezing, or the storage tank 106 is protected by frost damage due to a volume expansion of the thermal storage medium 108 during freezing.

[0235] To ensure an even stronger frost protection, in some embodiments an anti-freeze agent such as glycol is contained in the thermal storage medium 108 in a concentration of up to 50% to further lower the freezing point of the thermal storage medium 108, such as for example to −20° C. or −35°C.

[0236] Preferably, the heat storage and exchanger 100 (or the heat exchanger 104) is used as a counterflow heat exchanger, i.e. a fluid flow through the first fluid conduit 102a is directed opposite to a fluid flow through the second fluid conduit 102b. This further improves the effectiveness of the heat transfer between the first fluid conduit 102a and the second fluid conduit 102b.

[0237] FIG. 2a shows a heat storage and exchanger 100 according to a second exemplary embodiment, which is similar to that of FIG. 1. Corresponding elements are denoted by the same reference numerals, a repeated description is refrained from. The heat storage and exchanger 100 of FIG. 2a is formed with a number of modifications. Corresponding to different embodiments, a heat storage and exchanger 100 is formed with only one or a combination of the described modifications.

[0238] The height h of the section of the storage tank 106 provided for the thermal storage medium (not shown) is similar to the corresponding height in the heat storage and exchanger 100 of FIG. 1 and is approximately 2 m. In addition, the storage tank 106 of FIG. 2a comprises, above the section provided for the thermal storage medium, a section 142 (referred to as dome 142 in the context of this disclosure) which is not for the thermal storage medium, but provides space for other elements, in particular for the first fluid conduit 102a and the second fluid conduit 102b. In the embodiment shown, the first fluid conduit 102a and the second fluid conduit 102b pass through the dome 142 in a straight line in the vertical direction. The supply / discharge lines 112, 114 are thus arranged above the dome 142. In alternative embodiments, the first fluid conduit 102a and the second fluid conduit 102b bend in the dome coming from the bottom to the side (towards the horizontal direction). In corresponding embodiments, the supply / discharge lines 112, 114 are arranged laterally with respect to the dome 142.

[0239] For the use of the heat storage and exchanger 100 as an underground heat storage tank, the section of the storage tank 106 provided for the thermal storage medium is arranged in the soil, while the dome 142 is arranged at least partially above ground. Thus, the fluid conduits 102a, 102b are accessible from above ground for connecting.

[0240] An additional heat exchanger 118 with supply / discharge conduits 120 for a fluid is arranged in the storage tank 106 of FIG. 2a.

[0241] The additional heat exchanger 118 enables an effective and controllable thermal coupling of the heat storage and exchanger 100, or the thermal storage medium arranged therein, respectively, to a medium surrounding the storage tank 106, specifically to the soil in the case of an underground arrangement of the storage tank 106. For this purpose, an geothermal collector is arranged in the soil, and a fluid conduit of the geothermal collector is connected to the supply / discharge lines 120. Via a valve and / or a circulation pump, the flow of a fluid (for example, a brine) through the additional heat exchanger 118 and in series through the fluid conduit of the geothermal collector is controlled, and thus the thermal coupling of the heat storage and exchanger 100 to the soil.

[0242] In the embodiment shown, the fluid conduit of the additional heat exchanger 118 passes laterally through the storage tank 106. In other words, the supply / discharge lines 120 are arranged laterally with respect to the storage tank 106. In alternative embodiments, the fluid conduit of the additional heat exchanger 118 passes upwards (like the fluid conduits 102a, 102b) through the storage tank 106. In such embodiments, the supply / discharge lines 120 are arranged above the space of the storage tank 106 provided for the thermal storage medium 108. Similar to the supply / discharge lines 112, 114 described above, they may run partially horizontally above the storage medium 108. A corresponding arrangement can facilitate the connection of the supply / discharge lines 120 to the geothermal collector.

[0243] The heat exchanger 104 of FIG. 2a comprises a thermal insulation 140 in one of its end sections 138. It is formed as a sheathing of at least one of the fluid conduits 102a, 102b with a thermally insulating material, in particular a porous material and / or such a material with an evacuated region. In the embodiment shown with the double-pipe heat exchanger 104, the two fluid conduits 102a, 102b are sheathed.

[0244] The thermal insulation 140 thus defines the end region 138 of the heat exchanger 104 without thermal contact to the thermal storage medium 108, with the effects and advantages described in the context of the embodiment of FIG. 1. A difference between the two embodiments is that, in the embodiment of FIG. 1, the end region 138 of the heat exchanger without thermal contact to the thermal storage medium 108 is defined by that region of the heat exchanger 104 which is arranged outside the space of the storage tank 106 for the thermal storage medium 108 (e.g. above the target filling height 116).

[0245] By providing the thermal insulation 140, the extent and position of the end region 138 of the heat exchanger 104 without thermal contact to the thermal storage medium 108 (and thus the temperature matching of the fluid conduits 102a, 102b or of the fluids contained therein) may be set in a tailored manner and independently of the course of the fluid conduits 102a, 102b. In the embodiment shown, an end region 138 of the heat exchanger comprises the thermal insulation 140. In alternative embodiments, both end regions 138 are equipped with the thermal insulation.

[0246] The heat storage and exchanger 100 of FIG. 2a additionally comprises a pressure compensation vessel 130a, 130b, 130c.

[0247] The pressure compensation vessel 130a, 130b, 130c comprises a pressure compensation bag 130a for an expansion liquid 136, a riser 130b, and a pressure compensation tank 130c.

[0248] During operation, the pressure compensation bag 130a is filled with the expansion liquid 136 when the thermal storage medium is in the liquid aggregate state. In this state, the pressure compensation tank 130c provides a gas volume which at least corresponds to the volume increase of the thermal storage medium during freezing (e.g. 8% in the case of water).

[0249] If the thermal storage medium freezes during operation, its volume increases, in the case of water by approximately 8%. In this situation, the thermal storage medium compresses the pressure compensation bag 130a and pushes a part of the expansion liquid 136 previously contained therein through the riser 130b into the pressure compensation tank 130c. The expansion liquid 136 displaces the gas of the gas volume there. As a result, the thermal storage medium can expand without a risk that the storage tank 106 is damaged.

[0250] The heat storage and exchanger 100 in FIG. 2a is therefore particularly well suited for use as a low-temperature heat storage or as a cold storage tank.

[0251] As illustrated in FIG. 2b, the heat storage and exchanger 100 (in particular for use as a low-temperature heat storage or as a cold storage tank) in some embodiments comprises a circulation device 150, for example, a circulation pump 150 or an agitator 150. The circulation device circulates the storage medium 108 in the storage tank 106 when the temperature of the storage medium 108 reaches the freezing point thereof or falls below the freezing point thereof. In some embodiments (not shown), the heat storage and exchanger 100 comprises the circulation device 150 in addition to the pressure compensation vessel 130a, 130b, 130c.

[0252] By means of the circulation device 150, ice formation is reduced and the heat conduction in the storage tank 106 is improved. The circulation device 150 delays a stratification reversal, which otherwise occurs when, when using a water-comprising (i.e. aqueous) thermal storage medium, the temperature thereof passes through 4° C. Since the density of the aqueous thermal storage medium reaches its maximum at 4° C., at a (e.g. average) temperature of the storage tank (or of the thermal storage medium contained therein) at temperatures above 4° C, or below 4° C., respectively, warmer or colder thermal storage medium is located in the upper region of the thermal storage tank. In contrast, in the lower region of the thermal storage tank, colder or warmer thermal storage medium is located. When passing through the temperature of 4° C., the stratification reversal takes place. By means of the circulation device 150, a stratification of the thermal storage medium is reduced, and thus the stratification reversal is delayed and ultimately the ice formation is reduced.

[0253] The heat storage and exchanger 100 of FIG. 2b further includes a flow channel 146, 148 which is arranged in the thermal storage tank 106. The flow channel 146, 148 is arranged so that the flow channel 146, 148 defines a direction of the stream 152 generated by the circulation device 150 towards the heat exchanger 104 and / or so that the flow channel 146, 148 limits the stream generated by the circulation device 150; for this purpose, the flow channel 146, 148 encloses at least a section of the generated flow 152.

[0254] In the illustrated embodiment, the flow channel 146, 148 is formed by two tubes 146, 148 which are concentric with respect to each other.

[0255] The outer tube 148 encloses a section of the heat exchanger 104, as well as a section of the generated stream 152 and the circulation device 150 itself. Thus, the outer tube 148 limits the generated stream 152 to the outside and defines a direction of the generated stream 152 towards the heat exchanger 104 by preventing the stream 152 from moving too far away from the heat exchanger 104. The outer tube 148 is concentric with the double-pipe heat exchanger 104.

[0256] In the illustrated embodiment, the flow channel 146, 148 additionally comprises an inner tube 146, but this is optional and is omitted in some embodiments. The inner tube 146 further limits the generated stream 152, namely to the inside, and thus also defines a direction of the generated stream 152 towards the heat exchanger 104. The inner tube 146 is concentric with the double-pipe heat exchanger 104 and additionally with the outer tube 148.

[0257] The flow channel 146, 148 improves the effectiveness of the circulation device 150 by directing the stream 152 generated by the circulation device 150 towards the heat exchanger 104, i.e. by limiting the stream 152 and defining the direction of the stream 152 towards the heat exchanger 104. As a result, in all of the embodiments, the heat transfer between the heat exchanger 104 and the storage tank or thermal storage medium, respectively, is improved; correspondingly, the circulation device 150 and optionally the flow channel 146, 148 may be provided in connection with all of the described embodiments.

[0258] In addition, the circulation device may particularly effectively delay or avoid ice formation at the heat exchanger 104. Ice formation at the heat exchanger 104 is particularly undesirable since it may lead to a reduced heat conduction (in particular between the heat exchanger 104 and the thermal storage tank 106 or the thermal storage medium, respectively) or may even lead to frost damage at the heat exchanger 104.

[0259] The heat storage and exchanger 100 in FIG. 2b, like the heat storage and exchanger 100 in FIG. 2a, is therefore particularly well adapted for use as a latent heat storage or as an ice storage, respectively, and for use at temperatures around the freezing point. In order to further improve the suitability of the heat storage and exchanger 100 in FIG. 2b, optionally one or all of the features described in connection with FIG. 2a may be provided.

[0260] FIG. 3 shows a heat storage and exchanger 100 according to a third exemplary embodiment, which is similar to that of FIG. 1, FIG. 2a and that of FIG. 2b. Corresponding elements are denoted by the same reference numerals, a repeated description is refrained from. The heat storage and exchanger 100 of FIG. 3 is formed with a number of modifications. Corresponding to different embodiments, a heat storage and exchanger 100 is formed with only one or a combination of the described modifications.

[0261] The heat storage and exchanger 100 of FIG. 3 is configured as a multi-zone heat storage.

[0262] The heat storage and exchanger 100 of FIG. 3 includes three additional heat exchangers 118, 122, 126, which are arranged at different heights.

[0263] The thermal storage medium 108 in the storage tank 106 of the heat storage and exchanger 100 has a temperature profile, at which the temperature increases from bottom to top (temperature stratification). Thus, the different heights, at which the additional heat exchangers 118, 122, 126 are arranged in the storage tank 106, correspond to different temperatures of the thermal storage medium 108 in the storage tank 106.

[0264] The lowermost additional heat exchanger 118 serves for the thermal coupling to a geothermal collector or to the surrounding soil.

[0265] The middle additional heat exchanger 122 serves for the extraction of heat at a first, lower temperature, for example for a heating system.

[0266] The upper additional heat exchanger 126 serves for the extraction of heat at a second, higher temperature, for example for domestic hot water.

[0267] In the embodiment shown, the additional heat exchangers 118, 122, 126 or their supply / discharge lines 120, 124, 128 are guided laterally out of the storage tank 106. In alternative embodiments, the additional heat exchangers 118, 122, 126 or their supply / discharge lines 120, 124, 128 are guided upwards out of the storage tank 106, as described in the context of the embodiments of FIGS. 1, 2a, 2b for the first fluid conduit 102a and the second fluid conduit 102b. This can simplify the connection of further elements to the supply / discharge lines 120, 124, 128, in particular if the storage tank 106 is arranged for the most part (for example with regard to its height extension) underground, but its upper side protrudes out of the ground.

[0268] In some embodiments, the end region 138 of the heat exchanger comprises a thermal insulation 140, as described above. During operation, a fluid in the first fluid conduit 102a flows through this end region 138 to the supply / discharge line 114 out of the storage tank 106 (upwards in FIG. 3), for example to the warm side of a heat pump. In this case, its temperature is approached to that of a fluid flowing in the second fluid conduit 112b in the end region 138 from the supply line 112 into the storage tank 106 (downwards in FIG. 3), for example coming from a geothermal collector. If the temperature of the outflowing fluid in the first fluid conduit 102a is higher than that of the inflowing fluid in the second fluid conduit 102b, the outflowing fluid in the first fluid conduit 102a is cooled further (heat is extracted therefrom), the inflowing fluid in the second fluid conduit 102b is heated (absorbs heat). Thereby, the heat transfer in the heat storage and exchanger 100 can be further improved, and the efficiency (e.g. a coefficient of performance such as the annual performance factor) of the heat pump can be further improved.

[0269] The heat storage and exchanger 100 further comprises in the uppermost section of the storage tank 106 a section 138′ of the first fluid conduit 102a (not shown) which is thermally coupled to the region of the storage tank 106 for the thermal storage medium 108, but is thermally insulated from the second fluid conduit 102b. In this region, the double-pipe heat exchanger 104 is not formed. Rather, the first fluid conduit 102a is in direct thermal contact with the thermal storage medium 108 and forms a heat exchanger therewith, but is thermally insulated from the second fluid conduit 102b. For this purpose, the first fluid conduit 102a and the second fluid conduit 102b are spaced apart from each other in this section 138′ (e.g. by an insulating material or by the thermal storage medium 108). Preferably, the first fluid conduit 102a and the second fluid conduit 102b are guided in the section 138′ separately from each other from one of their supply / discharge lines 112, 114 into the storage tank, and are only brought together in the storage tank 106 to form the heat exchanger 104.

[0270] Accordingly, the first fluid conduit 102a transmits the heat contained therein (or in the fluid guided by it) directly after its entry into the storage tank 106 to the thermal storage medium 108 in the uppermost region of the storage tank 106. Typically, in this case, the first fluid conduit 102a in this region 138′ guides a fluid flowing into the storage tank 106 coming from the warm side of a heat pump. Thus, the heat transfer takes place at maximum temperature, i.e. substantially at the temperature of the warm side of the heat pump or at the temperature at which the fluid coming from the heat pump flows into the storage tank; in particular without a significant temperature loss due to heat transfer from the first fluid conduit 102a to the second fluid conduit 102b.

[0271] An upper region 132a of the lateral surface (upper lateral surface section) of the storage tank 106 comprises thermal insulation 134. The thermal insulation is not present in a lower region 132b of the lateral surface (lower lateral surface section) of the storage tank 106. In other words, the upper lateral surface section 132a is more strongly thermally insulated from a medium surrounding the storage tank 106 than the lower lateral surface section 134a, typically at least three times stronger (i.e. with a thermal conductivity at least three times lower).

[0272] The height extension h1 of the upper lateral surface section 132a is approximately twice as large as the height extension h2 of the lower lateral surface section 132b. In other words, the height extension h1 (h2) of the upper (or lower) lateral surface section 132a (132b) is approximately two thirds (approximately one third) of the height extension h of the region of the storage tank 106 provided for the thermal storage medium.

[0273] The weaker or substantially non-existent thermal insulation of the lower lateral surface section 132b leads to a thermal coupling of the lower lateral surface section 132b to the medium surrounding the storage tank 106, typically to the ground surrounding the storage tank 106.

[0274] Thus, the medium or soil surrounding the storage tank 106 is made usable as an additional thermal storage medium for heat at low temperature.

[0275] However, the upper region of the storage tank 106, in which the thermal storage medium has a higher temperature, is thermally insulated by the upper lateral surface section 132a and the insulation 134 in order to ensure a sufficiently high temperature in the upper region of the storage tank 106, for example for domestic hot water.

[0276] The heat storage and exchanger 100 in FIG. 3 is particularly well suited (e.g. due to its construction as a multi-zone heat storage) for use as a high-temperature heat storage.

[0277] FIG. 4 shows a system 200 with a heat storage and exchanger 100 according to a first exemplary embodiment.

[0278] The system 200 comprises the heat storage and exchanger 100, a second heat storage and exchanger 210, a controller 202, a heat pump 204, a solar system 206, 208.

[0279] The heat storage and exchanger 100 is similar to that of FIG. 1, FIG. 2a, FIG. 2b or FIG. 3.

[0280] According to the representation in FIG. 4, the second heat storage and exchanger 210 is also similar to that of FIG. 1, FIG. 2a, FIG. 2b or FIG. 3. In other embodiments, however, the second heat storage and exchanger 210 is constructed differently or more simply. Different embodiments are possible as long as the second heat storage and exchanger 210 comprises a storage tank 220, a first fluid conduit 212a and a second fluid conduit 212b and is configured to enable a transfer of heat between the first fluid conduit 212a and the storage tank 220 (or a thermal storage medium arranged therein) and between the second fluid conduit 212b and the storage tank 220 (or the thermal storage medium arranged therein). In the illustrated embodiment, this is achieved by a single heat exchanger 222, however, in alternative embodiments, several heat exchangers may be provided.

[0281] In alternative embodiments, the second heat storage and exchanger 210 is similar to at least one of the heat storage and exchangers 100 of FIG. 1, FIG. 2a, FIG. 2b or FIG. 3. The heat storage and exchanger 100 in FIG. 4 may be constructed more simply as long as it comprises the features described above in connection with the second heat storage and exchanger 210.

[0282] The system 200 is operated at least temporarily (e.g. during summer or winter) such that one of the heat storage and exchangers 100, 210 is operated as a low-temperature heat storage (i.e. as a cold storage tank) and the other heat storage and exchanger 100, 210 is operated as a high-temperature heat storage. During such use, the temperature spread between the cold storage tank and the high-temperature heat storage is kept as great as possible, e.g. in that during operation of the heat pump 204, heat is released from the latter into the high-temperature heat storage and cold is released into the cold storage tank. By using the two heat storage and exchangers 100, 210 in the system 200 as heat and cold storage tanks, as described above, the efficiency of the system 200 is improved compared to a conventional system for heat generation, in which the cold energy released by the heat pump is released as a waste product to the environment, e.g. to air or to groundwater. Likewise, the efficiency of the system 200 is improved compared to a conventional air conditioning system, in which the heat energy released by the heat pump is released as a waste product to the environment.

[0283] The system 200 also makes it possible to use both heat storage and exchangers 100, 210 temporarily, in particular at the transition from winter to summer or from summer to winter, as cold storage tanks or (high-temperature) heat storage tanks. Towards the end of winter, as much cold as possible is introduced into both heat storage and exchangers 100, 210 in order to be available for cooling in summer. Towards the end of summer, as much heat as possible is introduced into both heat storage and exchangers 100, 210 in order to be available for heating during winter.

[0284] The heat storage and exchanger 100 is thermally coupled to a cold side 214 of the heat pump 204 by means of the first fluid conduit 102a.

[0285] The heat storage and exchanger 100 is thermally coupled to the solar system 206, 208 by means of the second fluid conduit 102b.

[0286] The heat storage and exchanger 100 is thermally coupled to a geothermal collector 224 in the soil 230 by means of the additional heat exchanger 118. Alternatively or additionally, the thermal coupling between the heat storage and exchanger 100 and the soil 230 is mediated by the wall of the heat storage and exchanger 100.

[0287] Alternatively or additionally to the thermal coupling of the heat storage and exchanger 100 to the geothermal collector 224 and / or the soil 230, the additional heat exchanger 118 in some embodiments couples the heat storage and exchanger 100 to a (in particular local) heating network. For this purpose, the additional heat exchanger 118 is directly coupled to the (local) heating network (i.e., instead of to the geothermal collector 224 and / or the soil 230), or in series with the geothermal collector 224 and / or the soil 230. The latter embodiment is in particular advantageous for realizing a (local) heating network across a plurality of buildings or properties which are arranged in the environment of each other, i.e., in a quarter (or district). In this case, a system 200 for supplying it is installed in each building or on each property. The heat storage and exchangers 100 of the systems are connected to each other by means of the (e.g., in series with the) associated geothermal collectors 224 in order to realize a common heat storage (in particular a low-temperature heat storage or cold storage) of large capacity. Correspondingly, the heat storage and exchangers 210 of the systems 200 are connected to each other by means of the associated geothermal collectors 228 in order to realize an additional common heat storage (in particular a high-temperature heat storage) of large capacity.

[0288] The second heat storage and exchanger 210 is thermally coupled to a warm side 216 of the heat pump 204 via its first fluid conduit 212a.

[0289] The second heat storage and exchanger 210 is thermally coupled to the solar system 206, 208 via its second fluid conduit 212b.

[0290] The illustrated solar system 206, 208 consists of a photovoltaic system 206 and a photothermal system 208. In alternative embodiments, the solar system does not comprise a photovoltaic system 206 or a photothermal system 208, or it comprises a plurality of photovoltaic systems 206 or photothermal systems 208. The photovoltaic system 206 and the photothermal system 208 may be integrated with each other as a monolithic unit (e.g., a single system may take over the function as photovoltaic system 206 and photothermal system 208) or may be spatially separated from each other.

[0291] Optionally, the second heat storage and exchanger 210 is thermally coupled to a geothermal collector 228 in the soil 232 via the additional heat exchanger 218. Alternatively or additionally, the thermal coupling between the second heat storage and exchanger 210 and the soil 232 is mediated by the wall of the heat storage and exchanger 100, preferably by a lower lateral surface section of the storage tank 220, as described accordingly in the context of FIG. 3.

[0292] In addition to the fluid conduits depicted as a solid line, the system 200 includes control lines connecting the controller 202 to the other components. The control lines are depicted as dashed lines. The control lines are configured to transfer electrical signals and thereby enable to control, using the controller 202, the components connected to the controller 202.

[0293] In particular, the controller 202 is connected to the photovoltaic system 206 and the heat pump 204.

[0294] By means of its connection to the photovoltaic system 206, the controller 202 receives information with regard to the electrical power currently produced by the photovoltaic system 206.

[0295] By means of its connection to the heat pump 204, the controller 202 controls the operating state of the heat pump 204, i.e. the current power of the heat pump. In particular, the controller 202 may switch the heat pump 204 off or on.

[0296] The controller 202 also provides an input in order to receive, in addition to the electrical power currently produced by the photovoltaic system 206, further information relating to the availability of electrical power. This information relates, inter alia, to the availability of electrical power from wind power.

[0297] Optionally, the information relates to a consumption of electrical power, for example in a building associated with the system 200. In such embodiments, the availability of electrical power relates to the difference between electrical power provided, for example by the photovoltaic system 206 and / or a wind turbine, and the consumption of electrical power.

[0298] The controller 202 also provides an input in order to receive information relating to a heat demand, for example relating to a building or building complex to be supplied with heat.

[0299] In addition, the controller 202 is connected to temperature sensors which determine the temperature of the photovoltaic system 206, the photothermal system 208, the soil 230, the soil 232, the (in particular thermal storage medium of the) heat storage and exchanger 100 and the (in particular thermal storage medium of the) second heat storage and exchanger 210 and transmit it to the controller 202. If a heat storage and exchanger is configured as a multi-zone heat exchanger, it has several temperature sensors which are configured to determine the temperature at different heights of its storage tank and to transmit said temperature to the controller 202.

[0300] In addition, the controller 202 is connected to valves and flow regulators which are depicted as circles at connection points between fluid conduits. The controller regulates the direction and flow of the fluid flow through the respective fluid conduit by means of the valves and flow regulators. In addition, the controller 202 controls circulation pumps (not depicted) and thus also the flows of the fluid flows through the fluid conduits.

[0301] In particular, the controller 220 controls the flow (for example, the flow rate) through at least one of the fluid conduits 102a, 102b in order to control the temperature of a fluid when flowing out of one of the two fluid conduits 102a, 102b, for example, as described in connection with the end region 138 of FIGS. 1, 2a and 2b. In the same way, the controller 220 controls the flow (for example, the flow rate) through at least one of the fluid conduits 212a, 212b in order to control the temperature of a fluid when flowing out of one of the two fluid conduits 212a, 212b.

[0302] FIG. 5a shows a system according to a further exemplary embodiment, which is similar to that of FIG. 4. Corresponding elements are denoted by the same reference numerals, a repeated description is refrained from. In addition, FIG. 5a illustrates a first operating mode 500a of a method of operating the system according to one example.

[0303] In the first operating mode 500a of FIG. 5a, the controller 202 controls the heat pump 104 and the fluid flows through the fluid conduits such that

[0304] a closed fluid flow is generated through the solar system 206, 208, the second fluid conduit 102b and the heat exchanger 104;

[0305] the heat pump 204 is in the switched-on operating state;

[0306] a closed fluid flow is generated through the cold side 214 of the heat pump 204 and the first fluid conduit 102a; and

[0307] a closed fluid flow is generated through the warm side 216 of the heat pump 204 and the first fluid conduit 212a.

[0308] This first operating mode is advantageous in particular when the solar system 206, 208 has a higher temperature than the heat storage and exchanger 100 or its thermal storage medium. In this case, heat is transferred from the solar system 206, 208 into the heat storage and exchanger 100. The solar system thus serves as a photothermal system 208. In addition, the heat storage and exchanger 100 cools the solar system 206, 208, which increases the efficiency of the photovoltaic system 206.

[0309] The cooling of the photovoltaic system 206 is thereby further improved in that the fluid reaching the photovoltaic system 206 through the second fluid conduit 102b is in effective heat exchange with the cold fluid from the cold side 214 of the heat pump 204 flowing through the first fluid conduit 102a in the heat exchanger 104.

[0310] Since the heat exchanger 104 comprises at its end (as viewed along the direction of the fluid flow through the second fluid conduit 102b) a region which is thermally insulated from the thermal storage medium of the heat storage and exchanger 100, the fluid flow through the second fluid conduit 102b is cooled below the temperature of the (in particular thermal storage medium of the) heat storage and exchanger 100, which further improves the cooling of the photovoltaic system 206.

[0311] In the illustrated embodiment, the warm side 216 of the heat pump is thermally coupled to the second heat storage and exchanger 210, in particular to its first fluid conduit 212a. Thus, the heat from the warm side 216 of the heat pump 204 is stored in the second heat storage and exchanger 210 and made usable for times of poor availability.

[0312] Thus, this first operating mode is in particular also advantageous when the availability of electrical power for the operation of the heat pump 204 is good, in particular when the electrical power currently provided by the photovoltaic system 206 exceeds a predefined critical value or when electrical power is readily available according to another of the above-described criteria.

[0313] Here and in the following, operating modes in which the heat pump 204 is in the switched-on operating state are referred to as active. Active operating modes are characterized for example in that the heat pump is operated with a power of at least 10%, at least 20% or at least 30% of its maximum power, or in that the heat pump is operated with a power of at least 10%, at least 20% or at least 30% of a peak power of the photovoltaic system 206.

[0314] In all of the operating modes, when the availability of electrical power for the operation of the heat pump 204 is good (as illustrated above for the first operating mode), an active operating mode is always selected, in particular when the electrical power currently provided by the photovoltaic system 206 exceeds a current consumption of electrical energy and / or a predefined critical value. Thus, energy is then stored as heat in the second heat storage and exchanger 210 when it is particularly readily available as electrical power or even in excess. Alternatively, the active operating mode is selected when electrical power is readily available according to another of the above-described criteria.

[0315] FIG. 5b shows a system according to a further exemplary embodiment, which is similar to that of FIG. 4. Corresponding elements are denoted by the same reference numerals, a repeated description is refrained from. In addition, FIG. 5b illustrates a second operating mode 500p of a method of operating the system according to one example.

[0316] In the second operating mode 500p of FIG. 5b, the controller 202 controls the heat pump 104 and the fluid flows through the fluid conduits such that

[0317] a closed fluid flow is generated through the solar system 206, 208, the second fluid conduit 102b and the heat exchanger 104; and

[0318] the heat pump 204 is in the switched-off operating state.

[0319] In other words, the closed fluid flow through the second fluid conduit 102b in the second operating mode corresponds to that in the first operating mode, but with the heat pump 204 switched off. In other words, the second operating mode 500p as a passive operating mode corresponds to the first operating mode 500a as an active operating mode.

[0320] Alternatively to the illustrated embodiment wherein the fluid flow is directed through the first heat storage and exchanger 100, in a further embodiment (not shown), the fluid flow is directed through the second heat storage and exchanger 210. This can be achieved by switching the valves 508a, 508b.

[0321] Here and in the following, operating modes in which the heat pump 204 is in the switched-off operating state are referred to as passive. Passive operating modes are characterized for example in that the heat pump is operated with a power that corresponds to at most half, at most one third, at most one quarter, or at most one fifth of the power in the corresponding active operating mode. For example, the heat pump is operated with a power of at most 9%, at most 6% or at most 3% of its maximum power, or with a power of at most 9%, at most 6% or at most 3% of a peak power of the photovoltaic system 206.

[0322] In the second operating mode and in all of the other operating modes, a passive operating mode is always selected when the availability of electrical power for the operation of the heat pump 204 is poor, in particular when the electrical power currently provided by the photovoltaic system 206 falls below a current consumption of electrical energy and / or a second predefined critical value. Thus, a power consumption by the heat pump 204 is kept low when electrical power is poorly available.

[0323] Like the first operating mode 500a, this second operating mode 500p is advantageous in particular when the solar system 206, 208 has a higher temperature than the heat storage and exchanger 100 or its thermal storage medium, in order to achieve the advantages described above in connection with the first operating mode.

[0324] Furthermore, the second operating mode is advantageous when the temperature of the solar system 206, 208 is at or below the freezing point of water while the temperature of the heat storage and exchanger 100 or its thermal storage medium is above it. At corresponding temperatures, snow or ice may form on the solar system 206, 208. By operating the system in the second operating mode, for example at regular time intervals, snow or ice can be thawed. Thereby, more light can reach the solar system 206, 208 and it can provide more electrical power and / or heat.

[0325] FIG. 5c shows a system according to a further exemplary embodiment, which is similar to that of FIG. 4. Corresponding elements are denoted by the same reference numerals, a repeated description is refrained from. In addition, FIG. 5c illustrates the first operating mode 500a′ of the method of operating the system according to a further example.

[0326] The first operating mode 500a′ according to the exemplary embodiment of FIG. 5c is similar to the first operating mode 500a according to the exemplary embodiment of FIG. 5a. However, the controller 202 regulates such that the closed fluid flow through the photovoltaic system 206, the photothermal system 208, the second fluid conduit 102b and the heat exchanger 104 additionally passes through the geothermal collector 224 in series.

[0327] Thus, in corresponding embodiments, the geothermal collector 224 or the soil 230 can be used as an additional heat storage.

[0328] In the embodiment shown, the fluid passes through the geothermal collector 224 before it passes through the upper region of the storage tank 106. This is advantageous in particular when the temperature of the fluid, when it is fed into the geothermal collector 224 or after passing through the solar system 206, 208 (flow temperature), exceeds the temperature in the (in particular upper region of the) storage tank 106. Accordingly, the controller 202 receives information about the flow temperature and the temperature in the (upper region of the) storage tank 106. If the flow temperature exceeds the temperature in the (upper region of the) storage tank 106, the controller 202 selects the mode of operation 500a′ and this mode is executed.

[0329] In alternative embodiments (not shown), the fluid passes through the geothermal collector 224 after it has passed through the lower region of the storage tank 106. Corresponding embodiments are advantageous when the temperature of the geothermal storage tank is below the temperature of the (in particular lower region of the) storage tank 106. The controller 202 selects such a mode of operation and it is executed when the flow temperature is below the temperature in the (in particular lower region of the) storage tank 106.

[0330] FIG. 5d shows a system according to a further exemplary embodiment, which is similar to that of FIG. 4. Corresponding elements are denoted by the same reference numerals, a repeated description is refrained from. In addition, FIG. 5d illustrates a third operating mode 530 of a method of operating the system according to one example.

[0331] In the third operating mode 530, the controller 202 controls the heat pump 204 and the fluid flows through the fluid conduits such that

[0332] the heat pump 204 is in the switched-on operating state;

[0333] a closed fluid flow is generated through the cold side 214 of the heat pump 204 and the first fluid conduit 102a; and

[0334] a closed fluid flow is generated through the warm side 216 of the heat pump 204 and the first fluid conduit 212a.

[0335] The third operating mode 510 thus allows to transfer heat from the heat storage and exchanger 100 into the heat storage and exchanger 210. Thus, a sufficiently high temperature of the second heat storage and exchanger 210 or of its thermal storage medium can be ensured, in particular in the upper region thereof, in which the heat exchanger 126 extracts heat for domestic hot water. The temperature for domestic hot water is thus regularly sufficiently high to avoid a formation of legionella.

[0336] In the illustrated embodiment, in addition, heat from the warm side 216 of the heat pump 204 or cold from the cold side 214 of the heat pump 204 is transferred by means of the fluid conduit in 506b to a building 502 in order to heat or cool it. In alternative embodiments, the heat transfer or cold transfer to the building 502 does not take place. Whether heat or cold or neither of the two is to be transferred to the building 502 is determined by the controller 202 based on an actual temperature of the building 502 and a target temperature for the building 502, which a user sets. In other words, the system serves for heating or cooling depending on the target temperature and actual temperature of the building. The controller 202 controls the execution of the operating mode accordingly.

[0337] A corresponding heat or cold transfer to the building 502 is optionally possible in all other active operating modes, for example in the operating modes described above in connection with FIGS. 5a and 5c.

[0338] The third operating mode is an active operating mode that is executed when the availability of electrical power for operating the heat pump 204 is good. The availability of electrical power is determined by the controller 202 as described above.

[0339] FIG. 5e shows a system according to a further exemplary embodiment, which is similar to that of FIG. 4. Corresponding elements are denoted by the same reference numerals, a repeated description is refrained from. In addition, FIG. 5e illustrates a fourth operating mode 520 of a method of operating the system according to one example.

[0340] In the fourth operating mode 520, the controller 202 controls the heat pump 204 and the fluid flows through the fluid conduits such that

[0341] a closed fluid flow is generated through the solar system 206, 208 and the cold side 214 of the heat pump 204;

[0342] the heat pump 204 is in the switched-on operating state; and

[0343] a closed fluid flow is generated through the warm side 216 of the heat pump 204 and the first fluid conduit 212a.

[0344] Also in this operating mode, optionally heat or cold is transferred to the building 502, as described above in the context of the operating mode in FIG. 5d.

[0345] The fourth operating mode 520 enables the provision of heat from the solar system 206, 208 for heating the building 502 or for storing in the second heat storage and exchanger 210. Alternatively to storing in the second heat storage and exchanger 210, the heat may be stored in the heat storage and exchanger 100.

[0346] Alternatively to the (in particular, alternatively to the exclusive) storing the heat in the storage medium of the second heat storage and exchanger 210, the second heat storage and exchanger 210 may be connected in series with the geothermal collector 228, so that the heat is stored in the geothermal collector 228 and the second heat storage and exchanger 210.

[0347] Accordingly, when storing in the heat storage and exchanger 100, the geothermal collector 224 may be connected in series.

[0348] In the illustrated exemplary embodiment of the fourth operating mode 520, the heat is extracted from the solar system 206, 208 as a heat source. In alternative embodiments, the heat is extracted from one of the geothermal collectors 224, 228 as a heat source. In such embodiments, a closed fluid flow is generated through the geothermal collector 224 or 228 and the cold side 214 of the heat pump 204, instead of the closed fluid flow through the solar system 206, 208 and the cold side 214 of the heat pump 204. Preferably, the geothermal collector 224, the geothermal collector 228 or the solar system 206, 208 is selectively used as a heat source, depending on which of these elements has the highest temperature. The selection is made automatically by the controller 202 based on temperature sensors associated with these elements.

[0349] In the illustrated embodiment, the heat is supplied to the building 502 through the fluid conduit 506a by means of the heat pump 204 and the fluid conduit 506b. In alternative embodiments, instead, the heat is supplied to the building 502 through the fluid conduit 504, i.e. without using the heat pump 204 (and the fluid conduits 506a, 506b). Such alternative embodiments provide a passive operating mode which otherwise corresponds to the illustrated active operating mode. The passive operating mode is advantageous when the temperature of the solar system 206, 208 (or the temperature of one of the geothermal collectors in 224, 228) exceeds the temperature of the heat storage and exchanger 100 or its storage medium and / or when the availability of electrical power is poor.

[0350] FIG. 5f shows a system according to a further exemplary embodiment, which is similar to that of FIG. 4. Corresponding elements are denoted by the same reference numerals, a repeated description is refrained from. In addition, FIG. 5f illustrates a fifth operating mode 530 of a method of operating the system according to one example.

[0351] In the fifth operating mode 530, the controller 202 controls the fluid flows through the fluid conduits such that

[0352] a closed fluid flow is generated through the heat exchanger 126 and the building 502.

[0353] Correspondingly, heat for the building 502, for example for domestic hot water, can be extracted from the second heat storage and exchanger 210.

[0354] In alternative embodiments of the fifth operating mode 530, the heat for the building 502 is extracted from the second heat storage and exchanger 210 by means of the heat exchanger 122 or from the heat storage and exchanger 100 by means of the heat exchanger 118 or from the soil 230 or 232 by means of the geothermal collector 224 or by means of the geothermal collector 228.

[0355] Which heat exchanger 118, 122, 126 or geothermal collector 224, 228 is used is determined by the controller 202 based on temperatures at the respective heat exchangers 118, 122, 126 and based on a requested temperature, as well as based on the selection of an active or passive operating mode.

[0356] First, the controller 202 determines, based on the availability of electrical power, whether an active or passive operating mode is to be selected.

[0357] When a passive operating mode is selected or when the availability of electrical power is poor, the controller 202 selects the heat exchanger 118, 122, 126 or geothermal collector 224, 228 whose temperature exceeds the requested temperature by the smallest amount. If no heat exchanger 118, 122, 126 or geothermal collector 224, 228 whose temperature exceeds the requested temperature is found, the controller 202 selects the heat exchanger 118, 122, 126 or geothermal collector 224, 228 with the highest temperature or changes to an active operating mode.

[0358] When an active operating mode is selected or when the availability of electrical power is good, the controller 202 selects the heat exchanger 118, 122, 126 or geothermal collector 224, 228 and couples it to the cold side of the heat pump 204, for which the hot side 216 of the heat pump 204 exceeds the requested temperature by the smallest amount during operation (in particular with the advantageously available electrical power).

[0359] This procedure ensures that heat is extracted from the heat exchanger 118, 122, 126 or geothermal collector 224, 228 with the lowest possible temperature and thus improves the energy efficiency of the system.

[0360] Examples of corresponding variants 530′, 530″, 530′″ of the fifth operating mode 530 are depicted in FIG. 5g, FIG. 5h and FIG. 5i.

[0361] In the example 530′ of FIG. 5g, electrical power is readily available due to intense solar radiation on the photovoltaic system 206. The thermal storage medium of the heat storage and exchanger 100 has a temperature of −2° C. according to its freezing point, and the thermal storage medium of the second heat storage and exchanger 210 has a temperature of 60° C. in the upper region and of 20° C. in the lower region. The soil 230 or 232 has a temperature of 5° C. or 6° C., respectively. Such a situation can occur during the day at the end of winter or at the beginning of spring.

[0362] A floor heater in the building requests a temperature of 35° C. from the controller 202 based on a user selection.

[0363] In the example 530′, an active operating mode is selected based on the good availability of electrical power.

[0364] In the illustrated example, the electrical power provided by the photovoltaic system 206 is not sufficient to heat, when the heat pump 204 is operated with this power and with the fluid from the storage tank 106 having a temperature of −2° C. at the cold side 214 of the heat pump 204, the hot side 216 to the setpoint temperature of 35° C. However, the electrical power provided by the photovoltaic system 206 is sufficient to heat, when the heat pump 204 is operated with this power and with a fluid from the soil 230 having a temperature of 5° C. at the cold side 214 of the heat pump 204, the hot side 216 to the setpoint temperature of 35° C.

[0365] Thus, the controller 202 selects the geothermal collector 224 and couples it to the cold side 214 of the heat pump 204. The building 502 is heated from the warm side 216 of the heat pump 204.

[0366] In the example 530″ of FIG. 5h, electrical power is poorly available due to low solar radiation on the photovoltaic system 206. The thermal storage medium of the heat storage and exchanger 100 has a temperature of 11° C., and the thermal storage medium of the second heat storage and exchanger 210 has a temperature of 75° C. in the upper region and of 40° C. in the lower region. The soil 230 or 232 has a temperature of 13° C. or 18° C., respectively. Such a situation can occur in a night in summer.

[0367] A floor heater in the building requests a temperature of 18° C. from the controller 202 based on a user selection.

[0368] In the example 530″, a passive operating mode is selected based on the poor availability of electrical power.

[0369] In the embodiment shown, neither the temperature of the heat storage and exchanger 100 nor the temperature of the soil 230 is sufficient to provide the target temperature of 18° C. However, the temperature of the soil 232 is sufficient to provide the target temperature of 18° C.

[0370] Thus, the controller 202 selects the geothermal collector 228 and couples it to the building 502 for heating.

[0371] In the example 530″ of FIG. 5i, electrical power is poorly available due to low solar radiation on the photovoltaic system 206. The thermal storage medium of the heat storage and exchanger 100 has a temperature of 8° C., and the thermal storage medium of the second heat storage and exchanger 210 has a temperature of 70° C. in the upper region and of 40° C. in the lower region. The soil 230 or 232 has a temperature of 7° C. or 14° C., respectively. Such a situation can occur in a night in late summer or autumn, after the outside temperature has fallen seasonally compared to that of the example of FIG. 5h.

[0372] A floor heater in the building requests a temperature of 25° C. from the controller 202 based on a user selection.

[0373] In the example 530″, a passive operating mode is selected based on the poor availability of electrical power.

[0374] In the embodiment shown, neither the temperature of the heat storage and exchanger 100 nor the temperature of the soil 230, 232 is sufficient to provide the target temperature of 25° C. However, the temperature of the second heat storage and exchanger 210 is sufficient to provide the target temperature of 25° C.

[0375] Thus, the controller 202 selects the second heat storage and exchanger 210 and couples it to the building 502 for heating.

[0376] Preferably, during heating in a passive operating mode from one of the heat storage and exchangers 100, 210, the geothermal collector 224, 228 associated with the heat storage and exchanger 100, 210 is connected upstream of the heat storage and exchanger 100, 210, in particular when the temperature of the associated geothermal collector 224, 228 is above the return temperature of the fluid from the building 502.

[0377] Accordingly, in the example shown, the geothermal collector 228 is connected upstream of the second heat storage and exchanger 210. This results in preheating of the fluid from the building before it is conducted through the second heat storage and exchanger 210. The fluid thus extracts a part of the heat for heating the building 502 from the system at a lower temperature (from the geothermal collector 228) instead of at a higher temperature (from the second heat storage and exchanger 210). The heat extraction at a lower temperature further improves the energy efficiency of the system.

[0378] The person skilled in the art understands that the above examples are intended to illustrate only different operating modes of the system without any intention of restricting the teaching. For example, in embodiments, different thermal stores may be combined, for example by mixing liquid heat conducting media which are thermally coupled to different thermal stores, in particular by means of a mixing valve, in order to provide a requested temperature.

[0379] FIG. 6a shows a local heating network system 600 with a local heating network and a second local heating network. The local heating network and the second local heating network are each based on heat storage and exchangers 100 or systems 200. The heat storage and exchangers 100 may be similar to those of FIG. 1, FIG. 2a, FIG. 2b or FIG. 3. The systems 200 may be similar to those of FIG. 4, FIG. 5a, FIG. 5b, FIG. 5c, FIG. 5d, FIG. 5e, FIG. 5f, FIG. 5g, FIG. 5h or FIG. 5i.

[0380] The local heating network (or the second local heating network) serves for storing heat or cold with a larger thermal capacity than that which a single heat storage and exchanger 100 or a single system 200 would provide. The local heating network (or the second local heating network) is therefore also referred to as storage system (or complementary storage system) in the following.

[0381] The local heating network (i.e. storage system) comprises a plurality of the systems 200. Each of the systems 200 is associated with a building or property 602, e.g., arranged therein or thereon.

[0382] The systems 200 comprise a heat storage and exchanger 100 as well as optionally a second heat storage and exchanger 210, e.g., a second heat storage and exchanger 210 as described above in connection with FIG. 4.

[0383] Optionally, the systems 200 comprise geothermal collectors 224 associated with one of the heat storage and exchangers 100, 210 or two geothermal collectors 224, 228 associated with the two heat storage and exchangers 100, 210.

[0384] The heat storage and exchangers 100 are connected to form a storage system by means of the conduits 604, optionally in series with the geothermal collectors 224. Thus, the heat storage capacity of the storage system is increased compared to that of the individual systems 200. Depending on the embodiments, the storage system is a low-temperature storage system (cold storage system) made of low-temperature heat storage units 100 (cold storage units 100), for example, corresponding to FIG. 2a or FIG. 2b, or a high-temperature storage system made of high-temperature heat storage units 100, for example, corresponding to FIG. 3.

[0385] A corresponding high-temperature storage system is, in some embodiments, operated as a low-temperature energy network or as a cold heating network, i.e., at temperatures of the thermal storage medium in the range of 1° C. to 40° C., preferably in the range of 10° C. to 25° C.

[0386] Each of the systems 200 includes a pump (not shown) configured to drive a fluid flow in the conduits 604 and / or in the conduits 606, for example, a hydraulic pump. Preferably, the pump is controlled by the above-described controller 200, i.e., switched on or off as needed. Alternatively, a separate controller may be provided which is coupled to the controller 200. The provision of the pumps for the fluid flow in the conduits 604 and / or in the conduits 606 decentrally in the systems 200 enables the use of comparatively low-performance, cost-effective pumps, in comparison to a conventional system in which a central pump station is provided or a few pump stations are provided. In addition, the pressure distribution in the local heating network can be controlled in a comprehensive manner by, for example, increasing the current pump power of one of the pumps in order to compensate for a local pressure drop in the local heating network (e.g., due to a local constriction, for example, in one of the conduits 604, 604).

[0387] Thus, each of the properties 602 can also be supplied with heat (or cold) from the local heating network if, due to an increased heat demand (or cold demand) temporarily on the property 602 or due to a reduced energy or heat generation (e.g., a failure of the solar system) on the property 602, the capacity of the local heat storage and exchanger 100 arranged on the property 602 would already be exhausted.

[0388] The geothermal collectors 224, which are arranged in the environment of the heat storage and exchangers 100 and are thermally coupled thereto, further increase the heat storage capacity of the storage system. In some embodiments, additional geothermal collectors 224′, 224″ are arranged spaced apart from the heat storage and exchangers 100, e.g., between the properties 602 or outside of the properties 602, and are coupled to the storage system by means of the conduits 604.

[0389] The additional geothermal collector 224′ is implemented as a section of the conduit 604 with reduced thermal insulation, compared to other portions of the conduit 604, which are formed with full thermal insulation in order to enable a loss-free as possible transport of heat or cold, respectively. Due to the reduced thermal insulation, the conduit 224′, 604 is thermally coupled to the surrounding soil and thus implements the geothermal collector 224′.

[0390] The additional geothermal collector 224″ is similar to the geothermal collectors 224, 228 described in connection with FIG. 4. Using valves, it is selectively coupled to the conduit 604, and thus selectively coupled to the storage system.

[0391] Corresponding to the described (i.e., low-temperature or high-temperature) storage system, the second heat storage and exchangers 210 are connected by means of the conduits 606 to a second local heating network, i.e., to a complementary (i.e., high-temperature or low-temperature) storage system, in order to realize a complementary storage system with increased heat storage capacity. The second heat storage and exchangers 210 may be similar to the heat storage and exchangers 100 of FIG. 1, FIG. 2a, FIG. 2b or FIG. 3. Alternatively, instead of the second heat storage and exchangers 210, a system 200 may be provided which is similar to one of the systems 200 of FIG. 4, FIG. 5a, FIG. 5b, FIG. 5c, FIG. 5d, FIG. 5e, FIG. 5f, FIG. 5g, FIG. 5h or FIG. 5i.

[0392] As described for the heat storage and exchanger 100 and the geothermal collector 224, in some embodiments the second heat storage and exchanger 210 is coupled to a geothermal collector 228. In FIG. 6, the geothermal collector 228 for the property is shown at the bottom left. In some embodiments, additional geothermal collectors (not shown) are also connected to the complementary storage system. For this purpose, these additional geothermal collectors are coupled to the conduits 606, corresponding to the above-described coupling of the additional geothermal collectors 224′, 224″ to the conduits 604.

[0393] In some embodiments, thermally insulating dividing walls 608 are also provided in order to thermally insulate the second heat storage and exchanger 210 from the heat storage and exchanger 100 and / or the geothermal collector 224, as shown for the property at the top right in FIG. 6a. Alternatively or additionally, in some embodiments, thermally insulating dividing walls 608 are also provided in order to thermally insulate the geothermal collector 228 from the heat storage and exchanger 100 and / or the geothermal collector 224, as shown for the property at the bottom left in FIG. 6a. Further thermally insulating dividing walls 608 thermally insulate conduits 604, 606 of the local heating network and of the second local heating network from each other, as shown in FIG. 6a for the conduits 604, 606 between the two left-hand properties 602. Preferably, the thermally insulating dividing walls 608 are arranged at least partially underground, in particular in embodiments in which the heat storage and exchangers 100, 210 are arranged at least partially underground.

[0394] In preferred embodiments, corresponding thermally insulating dividing walls are used in order to define the geothermal collector 224 or the geothermal collector 228. In such embodiments, a laterally encircling thermally insulating dividing wall laterally delimits the geothermal collector 224 (or the geothermal collector 228). Optionally, an upper and / or lower thermally insulating dividing wall delimits the geothermal collector 224 (or the geothermal collector 228) in its vertical extension.

[0395] In preferred embodiments of the system 200 of FIGS. 4, 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h or 5i and of the local heating network system 600 of FIG. 6a, the geothermal collector 224 is adjacent to the geothermal collector 228 and is delimited laterally from the geothermal collector 228 by a thermally insulating dividing wall embedded in the soil.

[0396] In preferred embodiments, at least one of the systems 200 comprises a solar system 206, 208. In some embodiments, a locally delimited (e.g., on one of the properties 602 or outside of the properties 602) solar system 206, 208 is provided which provides a sufficient peak power to supply several properties 602. In alternative embodiments, the solar systems 206, 208 are distributed, i.e., each of the systems 200 comprises a solar system 206, 208.

[0397] FIGS. 6b, 6c, 6d and 6e show the coupling of a heat storage 100 to a storage system 600 according to different embodiments. The heat storage is preferably a heat storage 100 as described above in connection with FIGS. 1, 2a, 2b or 3 or the system 200 of FIGS. 4, 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h or 5i. The storage system is similar to that of FIG. 6a. The heat storage 100 may be a high-temperature heat storage 100 or a low-temperature heat storage 100; in particular, a high-temperature heat storage 100 which is coupled to a high-temperature storage system or a low-temperature heat storage 100 which is coupled to a low-temperature storage system.

[0398] In FIGS. 6b, 6c, the heat storage 100 is coupled purely thermally to the storage system. In such a coupling, no material exchange takes place between the thermal storage medium 108 in the storage tank 106 and the storage system (or a medium in the conduit 604 of the storage system). In other words, there is no fluid coupling between the storage tank 106 and the storage system (or a conduit 604 of the storage system). Corresponding embodiments have the advantage that the respective fluid circuits are separate and can be individually controlled in their composition. A contamination of one of the fluid circuits does not affect the other fluid circuit.

[0399] In some embodiments, the geothermal collector 230 is selectively thermally coupled to the storage system, as illustrated in FIGS. 6b, 6c. The selective thermal coupling between the storage system and the geothermal collector 230 can also be purely thermal in the sense described above, in particular if the thermal coupling between the storage tank 106 and the storage system is purely thermal. In some embodiments, it is formed in series with the storage system and the geothermal collector 230.

[0400] In FIGS. 6d, 6e, the heat storage 100 is fluidly coupled to the storage system. In such a coupling, a material exchange takes place between the thermal storage medium 108 in the storage tank 106 and the storage system (or a medium in the conduit 604 of the storage system). In other words, a fluid is flowed through the storage tank 106 and the conduit 604 during operation. In other words, there is a fluid coupling between the storage tank 106 and the storage system (or the conduit 604 of the storage system). Corresponding embodiments have the advantage that the entire storage system can operate not only as a thermal storage system but also as an electrochemical storage system. This is enabled by the exchange of the storage medium 108 and the electrolytes contained therein in the storage system.

[0401] In some embodiments, the geothermal collector 230 is selectively fluidly coupled to the storage system, as illustrated in FIGS. 6d, 6e. The selective fluid coupling between the storage system and the geothermal collector 230 can be formed in particular if the storage tank 106 and the storage system are fluidly coupled. In some embodiments, it is formed in series with the storage system and the geothermal collector 230.

[0402] FIGS. 7a, 7b, 7c, 7d and 7e show possible arrangements of a heat storage and exchanger 100 relative to a building 700 with which the heat storage and exchanger 100 is associated. The heat storage and exchanger 100 may be similar to those of FIG. 1, FIG. 2a, FIG. 2b or FIG. 3.

[0403] In FIG. 7a, the heat storage and exchanger 100 is arranged in the building 700. This enables a simple and cost-effective installation. In addition, the heat storage and exchanger 100 is protected from weather influences and its service life is improved.

[0404] In FIG. 7b, the heat storage and exchanger 100 is arranged outside the building 700. Such an arrangement is advantageous in particular when the heat exchanger 104 contains a refrigerant which is readily combustible or toxic. The arrangement of the heat storage and exchanger 100 outside the building 700 reduces resulting dangers for the occupants of the building 700.

[0405] In FIG. 7c, the heat storage and exchanger 100 is arranged below ground outside the building 700. As a result of the underground arrangement, the space above the heat storage and exchanger 100 is made usable. The heat storage and exchanger 100 is protected from weather influences. In addition, the heat storage and exchanger 100 may be effectively thermally coupled to the surrounding soil and a geothermal collector may be realized. An (at least partially) underground arrangement is also possible below the building 700.

[0406] The arrangement of the heat storage and exchanger 100 in FIG. 7d corresponds to that in FIG. 7c. Alternatively, an above ground arrangement of the heat storage and exchanger 100 is possible, as illustrated in FIG. 7b.

[0407] The heat storage and exchanger 100 of FIG. 7d is associated with a heat storage 702 to which the heat storage and exchanger 100 is thermally coupled (e.g. by means of one of the heat exchangers 104, 118, 122, 126). The associated heat storage 702 is arranged in the building 700.

[0408] FIG. 7e shows a particularly advantageous preferred arrangement with two heat storage and exchangers 100a, 100b, which are each arranged underground. One of the two heat storage and exchangers 100a, 100b is configured as a low-temperature heat storage (i.e. cold storage), for example, as described in the context of the heat storage and exchanger 100 of FIG. 2a or FIG. 2b, the other as high-temperature heat storage 100, for example, corresponding to the heat storage and exchanger 100 of FIG. 3.

[0409] One of the heat storage and exchangers 100a is coupled to the associated heat storage 702, as described above. In particular, the high-temperature heat storage (or the low-temperature heat storage) is coupled to the associated heat storage 702 to ensure an optimization for the heating (or the cooling) of the building 700.

[0410] The associated heat storage 702 is arranged in the building 700 and preferably configured as a multi-zone heat storage.

[0411] A thermally insulating dividing wall 608 is arranged between the heat storage and exchangers 100a, 100b, in particular between the storage tanks 106 thereof. In the embodiment shown, the thermally insulating dividing wall 608 between the heat storage and exchangers 100a, 100b is also arranged underground in the soil. In alternative embodiments (not shown), the heat storage and exchangers 100a, 100b are arranged adjacent to each other and / or in a common housing, without soil between them. In corresponding embodiments, the thermally insulating dividing wall 608 is also arranged in the common housing and thus preferably at least partially underground. In embodiments in which the system comprises the geothermal collectors 224, 228 associated with the heat storage and exchangers 100a, 100b, as described for example in connection with FIG. 4, alternatively to the illustrated dividing wall 608 or in addition thereto, a thermally insulating dividing wall 608 is arranged between the geothermal collectors 224, 228.

[0412] The thermally insulating dividing wall 608 enables an effective thermal insulation of the heat storage and exchangers 100a, 100b and / or of the geothermal collectors 224, 228, even when little space is available. This is advantageous in particular in residential areas with high property prices, for example for single-family or row houses, or also in the environment of small or medium-sized businesses, since the system with the thermally insulating dividing wall 608 may for example also be accommodated in a smaller farm.

[0413] The combination of the heat storage and exchanger 100 with the associated heat exchanger 702 improves for example the alternating use of the heat storage and exchanger 100 as a heat storage (e.g. during winter) and as a cold storage (e.g. at the transition from winter to summer), as described above. In winter, the heat storage and exchanger 100 and associated heat exchanger 702 may be kept at a highest possible temperature. At the transition from winter to summer, the heat storage and exchanger 100 may be kept at the lowest possible temperature, and for example may also freeze (i.e. be used as an ice storage), while the associated heat exchanger 702 is kept at a higher temperature, for example for domestic hot water and / or heating water for the building 700. In corresponding embodiments, the storing of cold in the heat storage and exchanger 100 is improved by utilizing the latent heat at the phase transition.

[0414] In alternative embodiments (not shown), the heat storage and exchanger 100 and the associated heat storage 702 of FIG. 7d are interchanged, i.e. the heat storage and exchanger 100 is arranged in the building 700 and the associated heat storage 702 is arranged outside the building 700. In corresponding embodiments, the improved cold storage, as described above, can likewise be achieved, wherein the associated heat storage 702 may freeze (i.e. be used as an ice storage).

[0415] FIG. 8 shows a system 200 with a heat storage and exchanger 100 and a second heat storage and exchanger 210. The system 200 is similar to that of FIGS. 4, 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h or 5i and may comprise one or all of the elements described there. The following description is accordingly restricted to additional elements.

[0416] In some embodiments, the heat storage and exchanger 100 is similar to that of FIG. 2a or of FIG. 2b, and the second heat storage and exchanger 210 is similar to the heat storage and exchanger 100 of FIG. 3.

[0417] In the system 200 of FIG. 8, the thermal storage media of the heat storage and exchangers 100, 210 are electrolytes for a redox flow battery, and the system 200 further comprises an electrochemical cell 800.

[0418] Preferably, the electrolyte comprises redox-active chemical compounds, in particular ions of a metal compound, preferably ions of a vanadium, sodium, zinc or iron compound, and / or redox-active organic compounds, preferably viologens, quinones, lignins or lignin sulfates.

[0419] For example, the electrolytes may be provided by vanadium (oxide) ions dissolved in water or by a saline solution in conjunction with aminoxyl radicals, such as 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO), and a viologen. However, the person skilled in the art understands that the aforementioned examples are merely exemplary and basically other electrolytes can be used.

[0420] Pumps arranged in the heat storage and exchangers 100, 210, the electrochemical cell 800, or in electrolyte conduits 802a, 802b therebetween, flow the electrolytes out of the heat storage and exchangers 100, 210 through the electrolyte conduits 802a, 802b to the electrochemical cell 800. The internal structure (not shown) of the electrochemical cell 800 comprises a plurality of electrochemical half-cells, a membrane therebetween, and electrodes associated with the electrochemical half-cells. The electrolyte conduits 802a, 802b lead to different electrochemical half-cells which are separated by the membrane, i.e. the electrolytes are flowed through these different electrochemical half-cells by means of the electrolyte conduits 802a, 802b. Generated current can be extracted at the associated electrodes.

[0421] The electrochemical cell 800 is thermally coupled to at least one of the heat storage and exchangers 100, 210. In the embodiment shown, the coupling, by means of the valves 806, takes place selectively to the fluid conduits 808a, 808b and thus selectively to the heat storage and exchangers 100, 210. However, in alternative embodiments, only the coupling to one of the heat storage and exchangers 100, 210, in particular the coupling by means of the fluid conduit 808b to the high-temperature heat storage 210, is present.

[0422] In the embodiment shown, the fluid conduits 808a, 808b couple the electrochemical cell 800 directly to the heat storage and exchangers 100, 210. In alternative embodiments, the coupling takes place selectively by means of the heat pump 204, i.e. the fluid conduits 808a, 808b are selectively coupled to the cold side 214 of the heat pump 204 instead of to the heat storage and exchangers 100, 210. When selecting the coupling to the cold side 214 of the heat pump 204, the warm side 216 of the heat pump 204 is thermally coupled to the heat storage and exchangers 100, 210.

[0423] In detail, the thermal coupling takes place by means of a heat exchanger 804 thermally coupled to the electrochemical cell 800. The latter may be thermally coupled on the outside to at least one of the electrochemical half-cells. Preferably, however, the heat exchanger 804 is arranged in at least one of the electrochemical half-cells. In some embodiments, sub-heat exchangers are arranged in a plurality of electrochemical half-cells, and the sub-heat exchangers are interconnected to form the heat exchanger 804, for example, in series.

[0424] In the embodiment shown, the electrochemical cell 800 is arranged spatially separate from the heat storage and exchangers 100, 210. In alternative embodiments (not shown), however, the electrochemical cell 800 is arranged in the heat storage and exchanger 100 or the heat storage and exchanger 210, so that a highly integrated system is provided for a quick and cost-effective assembly.

[0425] Through the double coupling of at least one of the heat storage and exchangers 100, 210 to the electrochemical cell 800, on the one hand by means of the electrolyte conduit 802a, 802b, and on the other hand by means of the thermal coupling through the fluid conduit 808a, 808b, the system 200 uses the electrochemical cell 800 twice. On the one hand, it serves for power generation using the electrolytes of the heat storage and exchangers 100, 210. On the other hand, the waste heat arising in the electrochemical cell 800 is stored in the heat storage and exchangers 100, 210 for (e.g., later) use. Conversely, the system uses the heat storage and exchanger 100, 210 (or the thermal storage medium contained therein) twice, on the one hand as an electrolyte for the electrochemical cell 800, and on the other hand as an energy storage for receiving the waste heat generated by the electrochemical cell 800.

[0426] If a temperature of the electrolyte in the storage tank should, as may be expected, reach temperature values outside optimum operating temperatures of the electrochemical cell 800, a thermal coupling between the electrolyte conduits and / or the supply conduits and heat consumers, such as heating conduits, can also be performed in order to obtain suitable operating temperatures in the electrochemical cell 800. Alternatively or additionally, a maximum storage temperature of the storage tank can be limited to a compatible temperature of the electrolyte, for example if above the maximum storage temperature chemical processes would prevent an effective storing of electrical energy, and the controller can correspondingly limit the operation of the heat pump.

[0427] Alternatively to the electrolytic cell or additionally thereto, the above-described heat storage and exchanger or the above-described system further comprises, according to some embodiments (not shown), a thermoelectrochemical cell, which can be coupled to the (first) heat storage and exchanger 100 and / or the second heat storage and exchanger 210 for generating electrical energy.

[0428] A thermoelectrochemical cell can utilize a temperature difference between two electrodes in order to convert thermal energy into electrical energy. For example, the thermoelectric cell can be based on a temperature-dependent redox pair, such as on a ferri / ferrocyanide pair, so that different temperature levels at the electrodes, such as 20° C. and 60° C., can be used for generating current.

[0429] A corresponding electrolyte solution for operating the thermoelectric cell can be stored in the storage tank of the first heat storage and exchanger 100 and / or the second heat storage and exchanger 210, or the thermoelectrochemical cell can be coupled to the first heat storage and exchanger 100 and / or the second heat storage and exchanger 210 via heat exchangers.

[0430] For example, the electrodes of the thermoelectrochemical cell can each be coupled to the first and the second heat storage and exchanger 100, 210 in order to generate a temperature difference in the thermoelectrochemical cell. The temperature difference can subsequently generate a potential difference, which can be tapped at the electrodes. Thus, the different temperature levels provided in the thermoelectrochemical cell by re-storage (exchange) in the heat storage and exchangers 100, 210 can be used for generating current.

[0431] Furthermore, the stored thermal energy in the (first) heat storage and exchanger 100 can also be used for regenerating an electrolyte solution in order to generate current, for example according to the operating principle of thermally regenerable electrochemical cycles (TREC) or thermally regenerable batteries (TRB). In other words, the system may comprise a TREC cell or a thermally regenerable battery and the controller may be configured to, depending on an availability of electrical energy, selectively couple the TREC cell or the thermally regenerable battery to the heat pump or the (first) heat storage and exchanger 100 in order to regenerate the TREC cell or the thermally regenerable battery.

[0432] FIGS. 9a and 9b show local heating networks 610a, 610b or a local heating network system 600 with an electrochemical cell 800 according to two embodiments. The local heating networks 610a, 610b or the local heating network system 600 are similar to the local heating network or local heating network system 600 described above in connection with FIGS. 6a-6e and may be formed with further elements described there, although these are not illustrated in FIGS. 9a, 9b in order to avoid repetitions. The electrochemical cell 800 is similar to that of the exemplary embodiment of FIG. 8.

[0433] In the exemplary embodiment of FIG. 9a, the heat storage and exchangers 100 of the local heating network 610a are fluidly coupled to or through the conduit(s) 604a, as described in detail in connection with FIGS. 6d, 6e. The heat storage and exchangers 100 of the local heating network 610b are similarly fluidly coupled to or through the conduit 604b. The thermal storage media of the heat storage and exchangers 100 are electrolytes as described in connection with FIG. 8. The local heating networks 610a, 610b are fluidly decoupled from each other (separated from each other) and preferably also thermally decoupled from each other.

[0434] An electrochemical cell 800 is selectively fluidly coupled to the conduits 604a, 604b or to the heat storage and exchangers 100 or to the local heating networks 610a, 610b by means of the valves 612 and the electrolyte conduits 802a, 802b. In particular, a half-cell of the electrochemical cell 800 is selectively fluidly coupled to the local heating network 610a (or to the conduit 604a thereof or to the heat storage and exchanger 100 thereof). A further half-cell of the electrochemical cell 800 is selectively fluid-coupled to the local heating network 610b (or to the conduit 604b thereof or to the heat storage and exchanger 100 thereof).

[0435] Thus, each of the local heating networks 610a, 610b serves as an electrochemical storage system for one of the half-cells, or the local heating networks 610a, 610b serve in their entirety as an electrochemical storage system for the electrochemical cell 800.

[0436] In the exemplary embodiment of FIG. 9b, the heat storage and exchangers 100 of the local heating network system 600 are fluid-coupled to or through the conduit(s) 604, as described in detail in connection with FIGS. 6d, 6e. In some embodiments, the corresponding heat storage and exchangers 100 serve as high-temperature heat storage of the local heating network system 600. The heat storage and exchangers 210 of the local heating network system 600 are fluid-coupled to or through the conduit 606, as described in detail in connection with FIGS. 6d, 6e. In some embodiments, the corresponding heat storage and exchangers 210 serve as low-temperature heat storage of the local heating network system 600. Alternatively, the heat storage and exchangers 100 serve as low-temperature heat storage and the heat storage and exchangers 210 serve as high-temperature heat storage of the local heating network system 600.

[0437] An electrochemical cell 800 is selectively fluidly coupled to the conduits 604, 606 or to the heat storage and exchangers 100, 210 by means of the valves 612 and the electrolyte conduits 802a, 802b. A half-cell of the electrochemical cell 800 is selectively fluid-coupled to the heat storage and exchangers 100, a further half-cell of the electrochemical cell 800 is selectively fluid-coupled to the heat storage and exchangers 210. Furthermore, the function and advantages correspond to those described in connection with FIG. 9a, wherein the two local heating networks of the local heating network system 600 (or their corresponding components) take the place of the local heating networks 610a, 610b of FIG. 9a (or their corresponding components).

[0438] In the embodiments of FIGS. 9a, 9b, the electrochemical cell 800 is preferably fluid-coupled to a local heating network 610a, 610b or a local heating network of the local heating network system 600 (or to the conduit 604, 604b, 606, 606b thereof, or to the heat storage and exchangers 100, 210 thereof), which is operated in a frost-free manner, for example at a temperature of at least 1° C, at least 10° C., at least 15° C. or at least 20° C. In some embodiments, the two half-cells of the electrochemical cell 800 described in connection with FIGS. 9a, 9b are each fluid-coupled to a corresponding local heating network (or a corresponding component thereof).

[0439] In the embodiments of FIGS. 9a, 9b, in addition to the fluid coupling of the electrolyte cell 800 to at least one of the local heating networks 610a, 610b or the local heating networks of the local heating network system 600 (or to the conduit 604, 604b, 606, 606b thereof, or to the heat storage and exchangers 100, 210 thereof), optionally a thermal coupling (not shown) of the electrolyte cell 800 to at least one of the heat storage and exchangers 100, 210 of the local heating network is provided, as described in the of the exemplary embodiment of FIG. 8. This thermal coupling is spatially separate from the aforementioned fluid coupling, for example by using at least one separate fluid conduit 808a, 808b (as described in FIG. 8, not shown in FIGS. 9a, 9b), which is fluidly separate from the electrolyte conduits 802a, 802b. In some embodiments, the electrolyte cell 800 comprises a heat exchanger 804, similar to the heat exchanger 804 described in FIG. 8, and this heat exchanger 804 is thermally coupled to at least one of the storage tanks 100, 210, and in some embodiments is purely thermally coupled (i.e. fluidly separate).LIST OF REFERENCE NUMERALS100, 100a, 100b Heat storage and exchanger

[0441] 102a, 102b First, second fluid conduit

[0442] 104 Heat exchanger

[0443] 106 Storage tank

[0444] 108 Thermal storage medium

[0445] 110 Region highlighted by dashed lines (with inner structure of the heat exchanger)

[0446] 112 Supply / discharge line of the first fluid conduit

[0447] 114 Supply / discharge line of the second fluid conduit

[0448] 116 Target filling height of the storage tank for the thermal storage medium

[0449] 118, 122, 126 Additional heat exchanger

[0450] 120, 124, 128 Supply / discharge line of the additional heat exchanger

[0451] 130a, 130b, 130c Pressure compensation tank

[0452] 132a Upper lateral surface section

[0453] 132b Lower lateral surface section

[0454] 134,140 Thermal insulation

[0455] 138 Second region of the heat exchanger, end region of the heat exchanger

[0456] 142 dome

[0457] 144 First region of the heat exchanger

[0458] 146, 148 Flow channel, tubes

[0459] 150 Circulation device

[0460] 152 Stream generated by the circulation device

[0461] 200 System

[0462] 202 Controller

[0463] 204 Heat pump

[0464] 206 Photovoltaic system (solar system)

[0465] 208 Solar thermal system (solar system)

[0466] 210 Second heat storage

[0467] 212a First fluid conduit of the second heat storage

[0468] 212b Second fluid conduit of the second heat storage

[0469] 214 Cold side of the heat pump

[0470] 216 Warm side of the heat pump

[0471] 218 Additional heat exchanger of the second heat storage

[0472] 220 Storage tank of the second heat storage

[0473] 222 Heat exchanger of the second heat storage

[0474] 224, 228 Geothermal collector

[0475] 230, 232 soil

[0476] 500a, 500a′ first mode of operation

[0477] 502 building

[0478] 504 fluid conduits to / from building

[0479] 506a fluid conduits to / from heat pump

[0480] 508a, 508b valves

[0481] 500p second mode of operation

[0482] 512 valves

[0483] 510 third mode of operation

[0484] 520 fourth mode of operation

[0485] 530, 530′, 530″, 530′″ fifth mode of operation

[0486] 600 local heating network

[0487] 602 building, property

[0488] 604, 606 conduits

[0489] 608 thermally insulating dividing wall

[0490] 224′, 224″ Additional geothermal collector

[0491] 700 building

[0492] 702 Associated heat storage

[0493] 800 Electrochemical cell

[0494] 802a, 80b Electrolyte conduit

[0495] 804 Heat exchanger of the electrochemical cell

[0496] 806 Flow control (valve or circulation pump)

[0497] 808a, 808b Fluid conduit

[0498] 610a, 610b Local heating network, further local heating network

[0499] 612 Valve

Claims

1-45. (canceled)46. A heat storage and exchanger comprising:a first fluid conduit and a second fluid conduit;a heat exchanger configured to transfer heat between the first fluid conduit and the second fluid conduit; anda storage tank configured to receive a thermal storage medium;wherein at least a section of the heat exchanger is arranged in the storage tank to enable a transfer of heat between the heat exchanger and the thermal storage medium.

47. The heat storage and exchanger according to claim 46, wherein the first fluid conduit and the second fluid conduit are in direct contact in the heat exchanger.

48. The heat storage and exchanger according to claim 47, wherein the first fluid conduit and the second fluid conduit are in direct contact in the heat exchanger in a section of at least 0.5 m.

49. The heat storage and exchanger according to claim 46, wherein:the second fluid conduit is thermally coupled to a solar system;the first fluid conduit is thermally coupled to a cold side of a heat pump;the storage tank is a cistern storage and is adapted for an underground arrangement; andthe storage tank has a volume for the thermal storage medium of at least 2 m3.

50. The heat storage and exchanger according to claim 46, wherein:the heat exchanger comprises a double-pipe heat exchanger;the first fluid conduit comprises an inner pipe of the double-pipe heat exchanger; andthe first fluid conduit is coupled to at least one of:a heat pump, and the cold side of a heat pump.

51. The heat storage and exchanger according to claim 46, wherein:one of the first fluid conduit and the second fluid conduit is configured to pass through an upper surface of the thermal storage medium at least twice when the thermal storage medium is arranged in the storage tank;said one of the first fluid conduit and the second fluid conduit passes through the storage tank at least twice in the uppermost fifth of its height extension;the heat storage and exchanger comprises at least two additional heat exchangers, wherein the at least two additional heat exchangers are arranged at different heights in the storage tank.

52. The heat storage and exchanger according to claim 46, wherein:the storage tank is configured as an ice storage;the storage tank comprises at least one of:a circulation device configured to circulate the thermal storage medium in the storage tank; anda pressure compensation vessel, wherein a gas volume of the pressure compensation vessel is at least 8% of a volume of the storage tank for the thermal storage medium;wherein the thermal storage medium is arranged in the storage tank, wherein the thermal storage medium has a freezing point of at most −2°C.

53. The heat storage and exchanger according to claim 46, wherein the storage tank comprises an upper lateral surface section and a lower lateral surface section, and wherein the upper lateral surface section comprises a stronger thermal insulation between the inner side and the outer side of the storage tank than the lower lateral surface section, wherein the lower region of the storage tank is thermally coupled to a surrounding soil.

54. The heat storage and exchanger according to claim 46, wherein the thermal storage medium is arranged in the storage tank and wherein the thermal storage medium is configured to provide an electrolyte for an electrochemical cell, wherein the heat storage and exchanger is configured to provide the thermal storage medium of the electrochemical cell in a fluid-coupled manner.

55. The heat storage and exchanger according to claim 46, wherein:a second section of the heat exchanger has no thermal contact with the thermal storage medium;the second section of the heat exchanger has a thermal insulation to the thermal storage medium; andthe second section of the heat exchanger is arranged above a target filling height of the storage tank for the thermal storage medium.

56. The heat storage and exchanger according to claim 46, further comprising at least one controller, wherein the at least one controller is configured to control a fluid flow through the first fluid conduit in dependence on a first parameter, wherein the first parameter is associated with at least one of:an availability of electrical power, andan electrical power provided by a photovoltaic system.

57. The heat storage and exchanger according to claim 56, wherein:the at least one controller is further configured to output a control signal for a heat pump in dependence on the first parameter, wherein the heat exchanger comprises a double-pipe heat exchanger, wherein the first fluid conduit comprises an inner pipe of the double-pipe heat exchanger, and wherein the first fluid conduit is coupled to the heat pump;the first parameter is associated with the electrical power provided by the solar system, and the system comprises the solar system; andthe second fluid conduit is thermally coupled to a solar system.

58. The heat storage and exchanger according to claim 56, further comprising a second heat storage and exchanger, wherein the second heat storage and exchanger comprises:a first fluid conduit and a second fluid conduit; anda storage tank configured to receive a thermal storage medium;wherein the second heat storage and exchanger is configured to enable a transfer of heat between the first fluid conduit and the thermal storage medium and between the second fluid conduit and the thermal storage medium;wherein the at least one controller is configured to control a fluid flow through the first fluid conduit of the second heat storage and exchanger together with the fluid flow through the first fluid conduit of the heat storage and exchanger.

59. The heat storage and exchanger according to claim 58, further comprising:a heat pump, wherein the at least one controller is further configured to output a control signal for the heat pump in dependence on the first parameter, wherein the heat exchanger comprises a double-pipe heat exchanger, wherein the first fluid conduit comprises an inner pipe of the double-pipe heat exchanger, and wherein the first fluid conduit is coupled to the heat pump;wherein the fluid flow through the first fluid conduit of one of the heat storage and exchanger and the second heat storage and exchanger is configured to thermally couple that heat storage and exchanger to a cold side of the heat pump, andthe fluid flow through the first fluid conduit of the other heat storage and exchanger is configured to thermally couple the other heat storage and exchanger to a warm side of the heat pump; andwherein the heat pump is configured to provide a power of at least 3 kW.

60. A system comprising:a first heat storage and exchanger and a second heat storage and exchanger, wherein the first heat storage and exchanger comprises:a first fluid conduit and a second fluid conduit;a heat exchanger configured to transfer heat between the first fluid conduit and the second fluid conduit; anda storage tank configured to receive a thermal storage medium, wherein:at least a section of the heat exchanger is arranged in the storage tank to enable a transfer of heat between the heat exchanger and the thermal storage medium; andthe first heat storage and exchanger has a volume for its thermal storage medium of at least 2 m2 and is arranged at least partially underground; andthe second heat storage and exchanger comprises:a first fluid conduit and a second fluid conduit; anda storage tank configured to receive a thermal storage medium, wherein:the second heat storage and exchanger is configured to enable a transfer of heat between the first fluid conduit and the thermal storage medium and between the second fluid conduit and the thermal storage medium;a heat pump configured to provide a power of at least 5 kW, wherein:a fluid flow through the first fluid conduit of one of the first and second heat storage and exchangers is configured to thermally couple that heat storage and exchanger to a cold side of the heat pump; anda fluid flow through the first fluid conduit of the other heat storage and exchanger is configured to thermally couple the other heat storage and exchanger to a warm side of the heat pump; anda controller configured to control an operating state of the heat pump, the fluid flow through the first fluid conduit of the first heat storage, and the fluid flow through the first fluid conduit of the second heat storage together in dependence on a first parameter, wherein the first parameter is associated with an electrical power provided by a photovoltaic system;wherein the second fluid conduit of at least one of the first heat storage and exchanger and the second heat storage and exchanger is coupled to a solar system.

61. A method of operating a system comprising a heat storage and exchanger, wherein the heat storage and exchanger comprises:a first fluid conduit and a second fluid conduit, wherein the first fluid conduit is coupled to a heat pump;a heat exchanger configured to transfer heat between the first fluid conduit and the second fluid conduit; anda storage tank configured to receive a thermal storage medium;wherein at least a section of the heat exchanger is arranged in the storage tank to enable a transfer of heat between the heat exchanger and the thermal storage medium;wherein the method comprises at least two modes of operation, the method comprising:selectively executing one of the at least two modes of operation;wherein the first mode of operation comprises:operating the heat pump at a first heat pump power; andgenerating a fluid flow through the first fluid conduit to transfer heat between the heat pump and the thermal storage medium; andwherein the second mode of operation comprises:operating the heat pump at a second heat pump power that is at most a quarter of the first heat pump power; andgenerating a stronger fluid flow through the second fluid conduit than through the first fluid conduit to transfer heat via the second fluid conduit.

62. The method of claim 61, wherein selectively executing one of the at least two modes of operation comprises automatically selecting between the first and second modes of operation based on a first parameter, wherein the first parameter is associated with an availability of electrical power.

63. The method according to claim 61, wherein the second fluid conduit is thermally coupled to a solar system and the method further comprises:operating the system in the second mode of operation when the temperature of the solar system is below the freezing point of water while the temperature of the thermal storage medium of the heat storage and exchanger is above the freezing point of water;wherein the method further comprises:controlling a flow of a fluid through at least one of the first fluid conduit and the second fluid conduit;to reduce a temperature difference between a first fluid flowing out of one of the first fluid conduit and the second fluid conduit and a second fluid flowing into the other of the first fluid conduit and the second fluid conduit; andto increase an additional temperature difference between the outflowing first fluid and the thermal storage medium.

64. The method according to claim 61, wherein the heat storage and exchanger comprises a fluid coupling of the thermal storage medium to an external conduit, said external conduit being external with respect to the storage tank, and wherein the method further comprises:transporting electrolyte through said fluid coupling.

65. The method according to claim 61, wherein the system further comprises a second heat storage and exchanger, wherein the second heat storage and exchanger comprises:a storage tank configured to receive a thermal storage medium; anda first fluid conduit and a second fluid conduit;wherein the second heat storage and exchanger is configured to enable a transfer of heat between the first fluid conduit and the thermal storage medium and between the second fluid conduit and the thermal storage medium;wherein the method further comprises:performing the method steps having a relation to the heat storage and exchanger correspondingly on the second heat storage and exchanger;wherein the first fluid conduit of one of the first and second heat storage and exchangers is coupled to a cold side of the heat pump; andwherein the first fluid conduit of the other of the first and second heat storage and exchangers is coupled to a warm side of the heat pump.

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