Cold storage and the use of such a cold storage system as an energy storage system in a building supply system

Abstract

The present invention relates to a cold storage device (1) comprising at least: a first storage container (11) for receiving a first refrigerant (K1); a second storage container (12) for a second refrigerant (K2), which is arranged around the first storage container (11) and completely incorporates the first storage container (11); and a third storage container (13) for a third refrigerant (K3), which in turn is arranged around the second storage container (12) and at least partially incorporates the second storage container (12); and the use of such a cold storage device (1) as an energy storage device in a building supply system comprising at least: a photothermal module (3), a heat pump (2), and a consumer.The cold storage unit (1) according to the invention can advantageously serve as a high-performance "battery" for sustainably generated energy and increases the independence and range of such a building supply system. The cold storage unit (1) is particularly well suited for retrofitting existing buildings that were previously heated with fossil fuels.

Description

[0001] The present invention relates to a cold storage device and the use of such a cold storage device as an energy storage device in a building supply system.

[0002] For the purposes of this invention, the term "building supply system" refers to a system for supplying any building with hot or cold drinking water, hot service water, particularly for heating systems, and / or cold service water, particularly for cooling systems or air conditioning systems. The present invention preferably relates to building supply systems in which the energy (electricity and / or heat) is generated via renewable energy sources, for example, using photovoltaic modules, solar collectors, or combined hybrid collectors or PVT modules, and which comprise at least one heat pump.

[0003] Heat pumps have become indispensable in modern building supply systems for heating buildings, providing hot drinking water and process heat, as well as for efficient cooling of buildings in summer. Heat sources for these heat pumps, especially brine-to-water heat pumps, can include geothermal probes, ice storage tanks, solar collectors, and photothermal (PVT) modules.

[0004] For example, DE 10 2019 135 681 A1 describes an energy storage system consisting of two containers, which can be partially embedded in the ground. The energy storage system can advantageously work in conjunction with other energy sources without increasing installation costs. EP 3 147 584 B1 also describes a liquid storage system for storing cold and hot liquids, which is characterized by minimal cooling and heat losses. Reference is also made to DE 20 2013 001 469 U1.

[0005] PVT modules can be advantageously used as air / water heat exchangers, thus providing an alternative heat source to traditional air / water heat pump systems. Compared to the particularly energy-efficient geothermal probe and ice storage systems, PVT module systems often prove to be more cost-effective while offering only slightly lower energy efficiency.

[0006] To ensure operational reliability, worst-case conditions, such as a period of bad weather with several cold days and cloudy skies, must be considered when designing building supply systems using PVT module systems. Current technology often involves particularly large dimensions for this purpose, which can disadvantageously lead to poor efficiency and / or frequent stagnation of the PVT system. As an alternative option for peak load coverage, current technology provides auxiliary heating as a heat source for the heat pump. These can be implemented, for example, in the form of fireplaces, small gas boilers, or additional pellet stoves. However, these auxiliary heating systems disadvantageously use fossil fuels, which significantly worsens the carbon footprint of the overall system.Another aspect of building supply – especially in light of climate change-related increases in average summer temperatures – concerns ensuring energy-efficient cooling of buildings.

[0007] Based on this, the present invention is based on the object of providing a technical solution that is improved over the prior art to ensure the operational reliability of a building supply system based on renewable and thus often weather-dependent energy sources while simultaneously being as climate-neutral as possible. The focus here should be particularly on building supply systems based on heat pump heating systems and using PVT modules as direct heat sources for the respective heat pump.

[0008] This object is achieved by a cold storage device having the features of independent patent claim 1 and by the use of such a cold storage device as an energy storage device in a building supply system according to patent claim 15.

[0009] The cold storage device according to the invention comprises at least a first storage container with an opening for filling the first storage container with a first refrigerant, at least one side wall and a base opposite the opening; a second storage container for a second refrigerant, which is arranged around the first storage container and completely accommodates the first storage container, so that at least the side wall and the base of the first storage container delimit the volume of the second storage container towards the first storage container; and a third storage container for a third refrigerant, which in turn is arranged around the second storage container and at least partially accommodates the second storage container; and wherein the second storage container comprises at least two inlets and at least two outlets for the second refrigerant.

[0010] The cold storage device according to the invention advantageously forms a tank-in-tank-in-tank system in which the first storage container as the inner tank and / or the third storage container as the outer tank can assume the role of cost-effective latent heat storage devices, which are in direct one-sided or two-sided thermal contact with the second refrigerant located in the second storage container, designed as a central tank. The heat capacity of the cold storage device according to the invention in the form of a tank-in-tank-in-tank system is thus advantageously increased many times over compared to the heat capacity of conventional buffer storage devices, in particular conventional combination storage devices of the prior art. Furthermore, the cold storage device according to the invention is particularly well suited for use in retrofitting / conversion or renovation projects.For example, an existing watertight basement room, which previously housed the oil tank of an oil heating system, can be converted into a third storage tank within the meaning of the present invention during a conversion to a heat pump heating system. It can be supplemented by a first and second storage tank within the meaning of the present invention, and thus advantageously converted into a cold storage unit according to the invention. Alternatively or cumulatively, a rainwater cistern, a rainwater tank, a retention chamber, and / or retention tank can also be used as a third storage tank within the meaning of the present invention. The preferably filtered and / or purified rainwater introduced into it can then advantageously become a further environmental source for a heat pump system.

[0011] The cold storage unit according to the invention is not only suitable as an energy source for the heating period, but also as a cooling storage unit for summer cooling operation, whereby cooling energy can advantageously be actively obtained through the domestic hot water production and also through the heat rejection via the PVT modules.

[0012] If such a cold storage system is used as an energy storage system in a building supply system, which comprises at least one photothermal module, a heat pump and a consumer, in particular in the form of a combination storage system for drinking and service water, a drinking water consumer and / or a heating system, a new but also any existing building can be equipped in a comparatively simple and cost-effective manner with a sustainable electricity and heating system with at least day / night balancing, multi-day to semi-seasonal ice storage with PVT regeneration (i.e. photo-thermal regeneration).

[0013] Further advantageous embodiments and developments, which can be used individually or in combination with one another, are the subject of the dependent claims.

[0014] In a preferred embodiment of the invention, the first storage container can be cylindrical or frustoconical, wherein the substantially circular boundary surface of the truncated cone with a smaller radius is formed by the base of the first storage container, and wherein the substantially circular boundary surface of the truncated cone with a larger radius is formed by the opening of the first storage container, so that the first storage container tapers from top to bottom when in use. Such a cylindrical or frustoconical first storage container, tapering from the opening to the base, advantageously offers the first coolant contained therein, which can in particular be water, the possibility of freezing from bottom to top, i.e. from the base to the opening, without there being a risk of the first storage container bursting.A cylindrical or truncated cone-shaped first storage tank tapering from the opening to the bottom can also advantageously act as a flow breaker and thus maintain better temperature stratification in the second storage tank.

[0015] Furthermore, it has proven useful if the second storage container comprises an inner base and an outer base which are separated from one another by a thermal insulation region, wherein the thermal insulation region is designed to thermally insulate the second storage container from the outside in the region of its inner and outer base. The thermal insulation region between the inner base and outer base can preferably have a width of between 5 and 150 mm, more preferably between 10 and 50 mm, wherein said width can also be different from the inside to the outside in the case of different curvatures of the inner base and outer base, i.e. can vary within the specified range. The thermal insulation region can preferably be designed as an evacuated region between the inner base and outer base; and / or comprise a plastic layer, in particular a polyethylene plate or polyethylene coating.A thermal insulation area in the area of ​​the inner and outer floor advantageously prevents icing below the outer floor of the second storage tank during operation and thus prevents the second storage tank from being pushed out of its anchorage within the third storage tank by expanding ice.

[0016] In a further preferred embodiment of the invention, it is advantageous if the second storage container can withstand an internal pressure of 2.5 to 3.5 bar, preferably 3.0 bar. Particularly when using the cold storage device as an energy storage device in a building supply system comprising at least one photothermal module, a heat pump, and a consumer, the cold storage device can be integrated via its at least two inlets and at least two outlets into a closed circuit of the second refrigerant, in particular a brine source circuit of the heat pump, in which an operating pressure of up to 3 bar generally prevails.

[0017] Also advantageous is an embodiment of the invention in which the third storage container is designed as a liquid-tight trough which accommodates the second storage container in such a way that the second storage container can be brought into contact with the third refrigerant at least in sections, in particular in a section up to 30% of a height of the second storage container, preferably up to 60% of its height.

[0018] The cold storage unit, in particular the second storage container, can preferably be made of stainless steel, especially chromium steel, thus eliminating the need for external insulation of the second storage container with an insulating material such as Armaflex. During operation of a building supply system according to the present invention, the second storage container would then be colder than the ambient temperature at the respective installation location (for example, the temperature in the basement in which the cold storage unit according to the invention is located), causing air humidity to condense on the outside of the second storage container. This would advantageously keep the installation location, in particular the basement, dry.

[0019] In this context, the design of the third storage tank as a liquid-tight tray advantageously enables the collection and drainage of said condensate. In a minimal design of said tray, its height can thus be only a few centimeters, i.e., a few percent of the height of the second storage tank, and it can preferably have a floor drain for the collected condensate. In a further preferred design, the third storage tank can also be designed as a classic, upwardly open collecting tray made of steel or plastic, which reaches 30 to 60 percent of the height of the second storage tank. The larger the volume of the third storage tank, the greater the additional energy gain in its function as a latent storage device.

[0020] On the other hand, a third storage container designed in this way also advantageously enables a simple and cost-effective installation of the cold storage device according to the invention in any room of a building and in particular offers simple possibilities for filling and emptying, for example via a mobile pump and / or a flexible hose system.

[0021] Alternatively, in a particularly preferred embodiment of the cold storage device, the third storage container can also be designed such that it completely accommodates the second storage container. Such a third storage container, which can be designed in particular as a floodable container, floodable tank, or preferably as a floodable space, in particular as a retention space or as a liquid-tight space, advantageously makes it possible to bring the second storage container into contact with the third refrigerant up to any desired height of the second storage container, as required. A liquid-tight space within the meaning of the present invention can, for example, be a space of tightness class 2 according to standard SIA 272 of the Swiss Society of Engineers and Architects.

[0022] The design as an entire room or cistern makes it possible, in particular, to flood the entire "tank-in-tank," i.e., the second storage tank within the third storage tank, by more than 50% or, preferably, to completely flood it. In a particularly preferred embodiment, the walls of the third storage tank, i.e., the room, cistern, or tank walls, are 20 to 100 cm, preferably 50 to 80 cm, away from the outer side wall of the second storage tank, so that complete freezing of the third refrigerant, in particular the water, up to the walls of the third storage tank is reduced or prevented. Such a system can advantageously store up to 12 times more energy than a simple state-of-the-art cold storage system of the same size.

[0023] It has proven particularly useful if the third storage tank comprises at least one inlet and at least one overflow for the third refrigerant, wherein the overflow is arranged at such a height on a wall of the third storage tank that the third storage tank can be filled with the third refrigerant to a maximum of 90% of a height of the third storage tank.

[0024] In this case too, the cold storage unit, in particular the second storage tank, can preferably be made of stainless steel, in particular chromium steel, which eliminates the need for external insulation of the second storage tank with an insulating material such as Armaflex. The third storage tank, which completely accommodates the second storage tank, can then be flooded with the third refrigerant, preferably up to a maximum of 90% of the height of the third storage tank. The third refrigerant surrounding the second storage tank can then advantageously also exchange heat with the second refrigerant inside the second storage tank and advantageously further increase the heat capacity of the entire system.In one embodiment of the invention, a particularly annular volume of approximately 20 to 50 cm thickness can be permitted around the outer wall of the second storage tank, in which the third refrigerant can freeze upon releasing heat to the second refrigerant. In the case of water as the third refrigerant, the third storage tank can advantageously provide a completely seasonal ice storage system, the hydraulics of which are significantly simpler and more cost-effective than a conventional ice storage system.

[0025] In this case, an overflow arranged at such a height on a wall of the third storage tank that the third storage tank can be filled with the third refrigerant to a maximum of 90% of a height of the third storage tank prevents the third refrigerant from freezing completely up to an upper limit or ceiling of the third storage tank and, in particular if the third refrigerant is water, from pressing against the upper limit or ceiling of the third storage tank.

[0026] In a further preferred embodiment of the invention, at least one guide element can be arranged inside the second storage tank in the region of at least one of the inlets, preferably in the region of both inlets. One or more guide elements advantageously make it possible to direct the respective inflow of second refrigerant into different layers of the second storage tank in a targeted manner, thus controlling the stratification of the second refrigerant in said second storage tank.

[0027] In a further preferred embodiment, the second storage container can comprise at least one third inlet and at least one third outlet for connection to at least one additional source, wherein a guide element can preferably be arranged in the region of the third inlet. The additional source can be an additional heat source, for example in the form of a fireplace, a small gas boiler, or a pellet stove, in order to be able to increase the temperature of the second refrigerant in the cold storage container in a controlled manner, preferably during the cold winter months. However, the additional source can also be an additional cooling device configured to lower the temperature of the second refrigerant in a controlled manner as needed.

[0028] Furthermore, an embodiment of the invention has proven successful in which the first refrigerant is a phase change material, in particular water or paraffin, the second refrigerant is ethylene glycol or an ethylene glycol-water mixture or propylene glycol or a propylene glycol-water mixture; and / or the third refrigerant is a phase change material, in particular water or paraffin.

[0029] If the first and / or third refrigerant, preferably both the first and third refrigerants, are formed as phase-change materials, the first storage container or the third storage container, or optionally both the first and third storage containers, can advantageously function as latent heat storage devices, which, as required, absorb thermal energy from the second refrigerant in the second storage container or release it to the second refrigerant. A particularly preferred embodiment is one in which rainwater is used as the first and / or third refrigerant. This rainwater can preferably be collected in the area of ​​the building to be supplied, optionally filtered, and then fed via pipelines to the first and / or third storage container.

[0030] The use of an ethylene glycol-water mixture as the second refrigerant advantageously enables comparatively cost-effective operation of the cold storage device according to the invention in a "normal" operating temperature range of -10 °C to + 15 °C in the second storage container. Increasing the ethylene glycol content of this mixture up to pure ethylene glycol advantageously enables the operating temperature range to be extended at low temperatures down to approximately -15 °C. Alternatively, a mixture of propylene glycol and water or pure propylene glycol can be used as the second refrigerant. The use of propylene glycol in a mixture with water advantageously allows operation at even lower refrigerant temperatures down to approximately -60 °C when using pure propylene glycol.

[0031] Finally, an embodiment of the invention has proven successful in which the cold storage device comprises at least two second storage containers, preferably a plurality of second storage containers.

[0032] In order to keep the production of the cold storage device according to the invention comparatively simple and cost-effective, the second storage container can preferably be manufactured in a fixed size. The use of several second storage containers in a cold storage device then advantageously enables scaling of the respective cold storage device in terms of performance and storable energy quantity. When using a cold storage device with several second storage containers as an energy storage device in a building supply system, comprising at least a photothermal module, a heat pump and a consumer, the second storage containers can preferably be connected in parallel to one another such that the pipes from the photothermal module to the heat pump and back are laid in a ring such that the sum of the lengths of the supply line and return line is essentially the same for each of the second storage containers.Such a piping layout, in this case within a parallel circuit, is also referred to as a Tichelmann piping layout. The piping can preferably be made of plastic, particularly polyethylene (PE) or polypropylene (PP), in order to advantageously minimize icing of the piping and limit it to the active surfaces of the cold storage unit.

[0033] Additional details and further advantages of the invention are described below with reference to preferred embodiments, to which the present invention is not limited, and in conjunction with the accompanying drawings.

[0034] It shows schematically: Fig. 1 shows an embodiment of a building supply system with a cold storage device according to the invention; Fig. 2 shows a first embodiment of a cold storage device according to the invention with a cylindrical first storage container and a third storage container designed as a liquid-tight tray; Fig. 3 shows a second embodiment of a cold storage device according to the invention with a truncated cone-shaped first storage container, in which the third storage container is designed such that it completely accommodates the second storage container; and Fig. 4 a design of a second storage container in a plan view.

[0035] In the following description of preferred embodiments of the present invention, like reference numerals designate like or comparable components.

[0036] Fig. 1 shows an embodiment of a building supply system with a cold storage unit 1 according to the invention.

[0037] The cold storage device 1 according to the invention is particularly suitable for use as an energy storage device in a building supply system. Fig. The building supply system shown in Figure 1 comprises, for example, a photothermal module 3, a heat pump 2, and various consumers, such as a combination storage tank 5 for drinking and domestic water, which in turn supplies various drinking water consumers 6, such as showers, taps, etc., with cold and / or hot drinking water. Furthermore, said combination storage tank 5 can also supply a heating system 7 with hot domestic water and / or an air conditioning system (not shown here) with cold domestic water. The cold storage unit 1 according to the invention is preferably connected between the photothermal module 3 and the heat pump 2. In addition, the cold storage unit 1 can also be connected to at least one additional source 4, for example in the form of a fireplace, a small gas boiler, or a pellet stove as an additional heat source, and / or in the form of an air conditioning system as an additional cooling device.

[0038] In Fig. 2 shows a first embodiment of a cold storage device 1 according to the invention with a cylindrical first storage container 11 and a third storage container 13 designed as a liquid-tight tray.

[0039] The cold storage device 1 according to the invention comprises at least a first storage container 11 with an opening 112 for filling the first storage container 11 with a first refrigerant K1. The filling can be carried out in particular via a hose line with a pump (not shown) or another supply line (also not shown). However, the first storage container 11 can also advantageously always be in mass exchange with its surroundings, in particular with a third storage container 13, via said opening 112, so that no higher pressure than the ambient pressure or the pressure in the third storage container 13 develops inside the first storage container 11, and in the case that the same phase change material, in particular water, is used as the first K1 and third K3 refrigerant, the first storage container 11 can be filled by flooding the third storage container (cf. also the embodiment in Fig. 3).

[0040] To prevent contamination and / or algae formation of the first refrigerant K1 located within the first storage tank 11, the opening 112 of the first storage tank 11 can be provided with a cover 111, which, however, is preferably designed to allow pressure equalization with the environment or with the third storage tank 13. The first storage tank 11 is delimited by at least one side wall 113 and a bottom 114 opposite the opening 112 to form a second storage tank 12 for a second refrigerant K2. For this purpose, the second storage tank 12 is arranged according to the invention around the first storage tank 11 and completely accommodates the first storage tank 11, so that the volume of the second storage tank 12 relative to the first storage tank 11 is delimited by said at least one side wall 113 and the bottom 114 of the first storage tank 11.The outer boundary, formed by the side wall 113 and the bottom 114 of the first storage tank 11, thus forms the inner boundary of the second storage tank 12. According to the invention, a third storage tank 13 for a third refrigerant K3 is arranged around the second storage tank 12. This third storage tank 13 at least partially accommodates the second storage tank 12.

[0041] The third storage container 13 can, for example, as in Fig. 2 - be designed as a liquid-tight trough that accommodates the second storage container 12 in such a way that the second storage container 12 can be brought into contact with the third refrigerant K3 at least in sections. The height 134 of the third storage container 13 designed as a trough can preferably be selected such that the third refrigerant K3 located in the third storage container 13 can collect up to a height that corresponds to 30% of a height 120 of the second storage container 12, preferably up to 60% of said height 120.In a minimal design of said tray, which is primarily used to collect and drain condensate forming on the outside of the outer side wall 1201 of the second storage tank 12, its height can in particular be only a few centimeters, i.e., a few percent of the height 120 of the second storage tank 12, and preferably have a floor drain for the collected condensate (not shown here). In said minimal design, the condensation enthalpy of the forming condensate can then advantageously be transferred to the second refrigerant K2 via the preferably uninsulated outer side wall 1201 of the second storage tank 12.

[0042] For demarcation from the outside, i.e., from the third storage container 13, the second storage container 12 can comprise, in addition to at least one outer side wall 1201, an inner base 127 and an outer base 129, which are preferably separated from one another by a thermal insulation region 128. The thermal insulation region 128 can then preferably be configured to thermally insulate the second storage container 12 from the outside in the region of its inner base 127 and outer base 129.The thermal insulation region 128 between the inner base 127 and the outer base 129 can preferably have a width of between 5 and 150 mm, more preferably between 10 and 50 mm, wherein said width can also be different from the inside to the outside in the case of different curvatures of the inner base 127 and the outer base 129, i.e. can vary within the specified range, and can be formed, for example, by a plastic layer, in particular a polyethylene plate or polyethylene coating, between the inner base 127 and the outer base 129. Particularly preferably, the thermal insulation region 128 can also, as shown in FIGS. Fig. 1 and Fig. 2, as an evacuated area between the inner floor 127 and the outer floor 129, wherein a plastic layer, as previously described, can also be arranged additionally within the evacuated area.

[0043] According to the invention, the second storage tank 12 comprises at least two inlets 121 and 123 and at least two outlets 122 and 124 for the second refrigerant K2, wherein one inlet-outlet pair, here exemplarily the first inlet 121 and the first outlet 122, can connect the second storage tank 12 to the photothermal (PVT) module 3; while the other inlet-outlet pair, here exemplarily the second inlet 123 and the second outlet 124, can connect the second storage tank 12 to the heat pump 2. Silicone sleeves for thermally insulating the inlet and / or outlet areas can be arranged around the inlets 121 and 123 and around the outlets 122 and 124, respectively, on the outside of the outer side wall 1201 of the second storage tank 12.

[0044] The second storage tank 12 can thus preferably form a closed circuit for the second refrigerant K2 with the PVT module 3 and the heat pump 2. The second storage tank 12 can therefore preferably be designed such that it can withstand an internal pressure of 2.5 to 3.5 bar, preferably 3.0 bar. Preferably, said second storage tank 12 can be made of chromium steel 1.4301 and have a height 120 of approximately 200 cm, a diameter of approximately 78 cm, and a filling capacity for the second refrigerant K2 of approximately 365 L. The first storage tank 11 surrounded by the second storage tank 12 can, in this example, have a filling capacity of 530 L, so that such a storage tank combination can advantageously achieve a storage capacity of, for example, 74 kWh in a temperature range of the second refrigerant K2 from -5 °C to +20 °C.However, the dimensions and fill contents of this storage combination can also be adjusted as needed. The example described here can also be applied to the . Fig. 3 shown design.

[0045] Fig. 3 shows a second embodiment of a cold storage device 1 according to the invention with a frustoconical first storage container 11, in which the third storage container 13 is designed such that it completely accommodates the second storage container 12.

[0046] Such a third storage tank 13, which completely accommodates the second storage tank 12, can preferably be formed by a floodable space, in particular a retention space or a liquid-tight space, such as a rainwater cistern or a converted oil tank. A "liquid-tight space" can in particular be a space of tightness class 2 according to standard SIA 272 of the Swiss Society of Engineers and Architects. In this way, existing building facilities, which were previously used, for example, for heating the building with fossil fuels, can be advantageously converted into a sustainable heating system.

[0047] As in Fig. 3, such a third storage tank 13 can comprise at least one inlet 131 and at least one overflow 132 for the third refrigerant K3, wherein the overflow 132 is preferably arranged at a height 135 on a wall of the third storage tank 13 such that the third storage tank 13 can be filled with the third refrigerant K3 to a maximum of 90% of a height 134 of the third storage tank 13. This advantageously ensures that such a third storage tank 13 cannot be filled completely up to the tank ceiling with the third refrigerant K3, so that, in particular when the third refrigerant K3 is water, which expands when it freezes, there is no risk of damage to the third storage tank 13 due to excessive pressure on the tank walls.The inlet 131 of such a third storage tank 13 can also advantageously be connected to a rainwater collection device, which can be arranged at a suitable location on the respective building. Fig. 3 also shows, in particular in the area of ​​the bottom 136 of the third storage tank 13, an example of a drain 133, which can preferably be arranged at the lowest point of the bottom 136 and can be configured to drain the third refrigerant K3 in a controlled manner if necessary - for example for maintenance and / or repair work on the second storage tank 12.

[0048] The second storage container 12 can, as in Fig. 3, comprise at least one third inlet 125 and at least one third outlet 126 for connection to at least one additional source 4, wherein a guide element 1251 can preferably be arranged in the region of the inlet 125. Similar guide elements 1211 or 1231 can also be arranged inside the second storage container 12 in the region of at least one of the inlets 121 or 123, preferably in the region of both inlets 121 and 123. Said guide elements 1211, 1231 and / or 1251 can in particular be manufactured as sheets of chromium steel, and accordingly arranged and / or shaped in the region of the respective inlet 121, 123 and / or 125 on the inside of the outer side wall 1201 of the second storage container 12 such that they direct the respective inlet flow into the desired layer within the second storage container 12.Said guide elements 1211, 1231 and / or 1251 in the areas of the first 121, the second 123 and / or the third 125 inlet can also be used in the case of the in . Fig. 2 illustrated embodiment of the invention.

[0049] Fig. 4 finally shows an embodiment of a second storage container 12 in a plan view.

[0050] The first storage container 11 located within the second storage container 12 can in principle take on any desired shape, possibly also having more than one side wall 113, for example if the first storage container 11 is approximately prism-shaped with a different base area (triangle, square, pentagon, ...).

[0051] Together with the schematic side views of various designs of the combination of first 11 and second 12 storage tank in the Fig. 2 and Fig.3, however, it is apparent that the first storage container 11 can preferably be cylindrical or frustoconical, wherein a substantially circular boundary surface of the truncated cone with a smaller radius r is preferably formed by the bottom 114 of the first storage container 11, a substantially circular boundary surface of the truncated cone with a larger radius R is preferably formed by the opening 112 of the first storage container 11 and a lateral surface of the truncated cone is formed by the at least one side wall 113 of the first storage container 11, so that the first storage container 11 tapers from top to bottom in the state of use (i.e. in the assembled, upright state of the cold storage device 1).Both a cylindrical and a frustoconical design of the first storage tank 11, tapering towards the bottom 114 of the first storage tank 11 and thus also towards the bottom 136 of the third storage tank 13, advantageously ensures reliable freezing of the first refrigerant K1 in the first storage tank 11 from bottom to top, i.e. from the bottom 114 to the opening 112, without there being a risk of the first storage tank 11 bursting. This is particularly true if the inner wall 113 and / or the bottom 114 of the first storage tank 11 have a wall thickness of 7 mm. A cylindrical or frustoconical first storage tank 11, tapering from the opening 112 to the bottom 114, can also act as a flow breaker and enable or maintain better temperature stratification in the second storage tank 12.

[0052] In all embodiments of the present invention, a phase change material, in particular water or paraffin, can preferably be used as the first refrigerant K1. The third refrigerant K3 can also preferably be a phase change material, in particular water or paraffin, in all embodiments, with particular preference also being given to embodiments of the present invention in which the same phase change material, preferably water, is used as the first K1 and third K3 refrigerants. The operating costs of such an embodiment of the cold storage device 1, in particular when rainwater is used as the water source, are advantageously particularly low. Said rainwater can advantageously be filtered before being introduced into the first 11 or third 13 storage tanks.As the second refrigerant K2, ethylene glycol or an ethylene glycol-water mixture or propylene glycol or propylene glycol-water mixture can be used, whereby the use of an ethylene glycol-water mixture can again advantageously reduce operating costs.

[0053] Finally, the cold storage unit 1 can also comprise at least two second storage containers 12, preferably a plurality of second storage containers 12, which can be interconnected in particular within the framework of a parallel circuit with so-called Tichelmann pipe routing, which advantageously enables scaling of the respective cold storage unit 1 in terms of performance and storable amount of energy.

[0054] The present invention relates to a cold storage device 1 comprising at least: a first storage container 11 for holding a first refrigerant K1; a second storage container 12 for a second refrigerant K2, which is arranged around the first storage container 11 and completely accommodates the first storage container 11; and a third storage container 13 for a third refrigerant K3, which in turn is arranged around the second storage container 12 and at least partially accommodates the second storage container 12; as well as a use of such a cold storage device 1 as an energy storage device in a building supply system comprising at least: a photothermal module 3, a heat pump 2, and a consumer. The cold storage device 1 according to the invention can advantageously serve as a powerful "battery" for sustainably generated energy and increases the independence and range of such a building supply system.The cold storage facility 1 is particularly suitable for converting existing buildings that were previously heated with fossil fuels. List of reference symbols 1 cold storage 11 first storage tank 111 Cover of the first storage tank (11) 112 Opening of the first storage tank (11) 113 Inner wall of the first storage tank (11) 114 Bottom of the first storage tank (11) 12 second storage tank 120 Height of the second storage tank (12) 1201 outer side wall 121 first inlet from the PVT module (3) 1211 first guide element 122 first process to the PVT module (3) 123 second inlet from the heat pump (2) 1231 second guide element 124 second drain to the heat pump (2) 125 third inflow from the additional source (4) 1251 third guide element 126 third process to the additional source (4) 127 Inner bottom of the second storage tank (12) 128 thermal insulation area 129 Outer bottom of the second storage tank (12) 13 third storage tank 131 inlet 132 Overflow 133 Process 134 Height of the third storage tank (13) 135 Height of the overflow (132) 136 Bottom of the third storage tank (13) 2 heat pumps 3 Photothermal (PVT) module 4 Additional source 5 combo storage tanks 6 drinking water consumers 7 Building heating K1 first refrigerant K2 second refrigerant K3 third refrigerant r radius of the ground (113) R radius of the opening (114)

Claims

[1] Cold storage (1) comprising at least: - a first storage container (11) with an opening (112) for filling the first storage container (11) with a first refrigerant (K1), at least one side wall (113) and a bottom (114) opposite the opening (112); - a second storage tank (12) for a second refrigerant (K2), which is arranged around the first storage tank (11) and completely accommodates the first storage tank (11), so that at least the side wall (113) and the bottom (114) of the first storage tank (11) delimit the volume of the second storage tank (12) towards the first storage tank (11); - and a third storage tank (13) for a third refrigerant (K3), which in turn is arranged around the second storage tank (12) and at least partially accommodates the second storage tank (12); - and wherein the second storage tank (12) comprises at least two inlets (121; 123) and at least two outlets (122; 124) for the second refrigerant (K2). [2] Cold storage device (1) according to claim 1, characterized by in that the first storage container (11) is cylindrical or frustoconical, wherein a substantially circular boundary surface of the truncated cone with a smaller radius (r) is formed by the bottom (114) of the first storage container (11), a substantially circular boundary surface of the truncated cone with a larger radius (R) is formed by the opening (112) of the first storage container (11), and a lateral surface of the truncated cone is formed by the at least one side wall (113) of the first storage container (11), so that the first storage container (11) tapers from top to bottom in the use state. [3] Cold storage device (1) according to claim 1 or 2, characterized byin that the second storage container (12) comprises an inner base (127) and an outer base (129) which are separated from one another by a thermal insulation region (128), wherein the thermal insulation region (128) is designed to thermally insulate the second storage container (12) from the outside in the region of its inner (127) and outer base (129). [4] Cold storage device (1) according to claim 3, characterized by that the thermal insulation area (128) between the inner floor (127) and the outer floor (129) has a width between 5 and 150 mm, preferably between 10 and 50 mm. [5] Cold storage device (1) according to claim 3 or 4, characterized by , - that the thermal insulation area (128) is formed as an evacuated area between the inner floor (127) and the outer floor (129); and / or - that the thermal insulation region (128) comprises a plastic layer, in particular a polyethylene plate or polyethylene coating. [6] Cold storage device (1) according to one of the preceding claims, characterized by that the second storage container (12) can withstand an internal pressure of 2.5 to 3.5 bar, preferably 3.0 bar. [7] Cold storage device (1) according to one of claims 1 to 6, characterized by that the third storage container (13) is designed as a liquid-tight trough which accommodates the second storage container (12) in such a way that the second storage container (12) can be brought into contact with the third refrigerant (K3) at least in sections, in particular in a section up to 30% of a height (120) of the second storage container (12), preferably up to 60% of its height. [8] Cold storage device (1) according to one of claims 1 to 6, characterized by that the third storage container (13) is designed such that it completely accommodates the second storage container (12). [9] Cold storage device (1) according to claim 8, characterized bythat the third storage container (13) is a floodable space, in particular a retention space or a liquid-tight space. [10] Cold storage device (1) according to claim 8 or 9, characterized by in that the third storage tank (13) comprises at least one inlet (131) and at least one overflow (132) for the third refrigerant (K3), wherein the overflow (132) is arranged at such a height (135) on a wall of the third storage tank (13) that the third storage tank (13) can be filled with the third refrigerant (K3) to a maximum of 90% of a height (134) of the third storage tank (13). [11] Cold storage device (1) according to one of the preceding claims, characterized by that in the interior of the second storage container (12) in the region of at least one of the inlets (121; 123), preferably in the region of both inlets (121; 132), at least one guide element (1211; 1231) is arranged. [12] Cold storage device (1) according to one of the preceding claims, characterized by that the second storage container (12) comprises at least one third inlet (125) and at least one third outlet (126) for connection to at least one additional source (4), wherein a guide element (1251) is preferably arranged in the region of the inlet (125). [13] Cold storage device (1) according to one of the preceding claims, characterized by , - that the first refrigerant (K1) is a phase change material, in particular water or paraffin; - that the second refrigerant (K2) is ethylene glycol or an ethylene glycol-water mixture or propylene glycol or a propylene glycol-water mixture; and / or - that the third refrigerant (K3) is a phase change material, in particular water or paraffin. [14] Cold storage device (1) according to one of the preceding claims, characterized by that the cold storage device (1) comprises at least two second storage containers (12), preferably a plurality of second storage containers (12). [15] Use of a cold storage device (1) according to one of claims 1 to 14 as an energy storage device in a building supply system, at least comprising: - a photothermal module (3), - a heat pump (2) and - a consumer, in particular in the form of a combination storage tank (5) for drinking and service water, a drinking water consumer (6) and / or a heating system (7).

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