Bivalent multifunction storage system

Abstract

The invention relates to a multi-functional storage system 1 for generating heating energy and for domestic hot water heating. The system comprises a multi-zone stratified storage tank with a buffer storage zone 5 and a hot water charging zone 6 above it, featuring a storage medium 3 with stratified charge at different temperatures; a counterflow domestic hot water heater 10, with a domestic hot water line 11 and a flow line 14 such that a flow gap 15 exists between them; a domestic hot water charging pump 18 for charging the flow gap 15 with the storage medium 3; a control unit 21 for operating the multi-functional storage system 1; and an electric heating element 20.1, the heating surface of which is arranged within the hot water charging zone 6, with the heating area extending at most to the eighth coil of the domestic hot water line 11. The invention also relates to a method for operating the multi-functional storage system 1. (Fig. 1)

Description

[0001] The invention relates generally to a bivalent multifunctional storage system according to the preamble of the main claim. This comprises a buffer storage tank as part of a heating system and a device for hot water preparation.

[0002] Multifunctional storage systems as defined in the invention include, in particular, buffer storage tanks, which are designed, for example, as multi-zone stratified storage tanks with integrated domestic hot water preparation. The buffer storage tank is connected to an external heat source, such as a heating system and / or a heat pump or a solar thermal system, which charges the buffer storage tank with heating water via a flow line. This heating water has the temperature required for space heating. This heat source is referred to below as "external" because it is not part of the multifunctional storage system.

[0003] To generate heat and hot water, the storage tank is filled with heating water, although any other heat-transferring storage medium is also suitable. The storage medium in the tank is heated by means of the heat source or by a heating surface located inside the tank, which is connected to a heat source, for example, a heat pump, such that the storage tank always contains a stratified charge with several layers of the storage medium at different temperatures. The temperature stratification is set and maintained such that the stratified charge has at least one buffer storage zone and at least one hot water charging zone above it. Various designs of the stratified storage tank and / or the use of suitable baffles, dividers, or other devices are employed to create and maintain the stratification of the storage medium.Perforated discs with an outer annular gap, flow guides, and other internal components are used in the storage tank. If the hot water charging zone is not separated from the buffer storage zone by a perforated disc, a person skilled in the art can also identify the two zones of the multi-zone stratified storage tank based on other features, such as the density and pitch of the coils or the temperature distribution in the storage medium.

[0004] A counterflow domestic hot water heater is typically integrated into the multi-zone stratified storage tank for hot water production. The cold water inlet is located on the cold side of the storage tank, and the hot water outlet is on the hot side. The counterflow domestic hot water heater comprises the domestic hot water pipe and a flow channel that surrounds the pipe and creates a flow gap. The heat exchanger surface is designed, with regard to the material and, where applicable, the surface finish of the pipe, to ensure efficient heat transfer to the domestic hot water flowing through it.

[0005] The counterflow domestic hot water heater also includes a domestic hot water charging pump for charging the flow gap with the storage medium in which the counterflow domestic hot water heater is located. Of the two pipes used in the counterflow system, the domestic hot water flows from bottom to top, and the storage medium flows from top to bottom in the flow gap. To generate the flow in the flow gap, the storage medium is pumped from the upper part of the hot water charging zone into the inlet of the flow gap located there by the domestic hot water charging pump. The inlet is typically located one or two coils below the outlet of the domestic hot water pipe from the storage tank, so that these coils are in direct thermal contact with the storage medium in the storage tank.The counterflow domestic hot water heater also includes sensors and a circulation line, with the circulation line connecting to the domestic hot water line at the return connection. The amount of water circulating in the system depends directly on the heat input from the storage medium, while maintaining the temperature stratification within the storage medium as much as possible.

[0006] The use of such an instantaneous water heater improves the cooling of the storage medium to near the temperature of cold water, and thus the discharge efficiency of the multi-functional storage tank. Its basic structure within the multi-zone stratified storage tank is also well known to those skilled in the art.

[0007] A multifunctional storage system also includes a control unit designed and configured to operate the system. This control unit communicates with temperature sensors that measure the temperature of the storage medium at various points within the storage tank, including temperature stratification, particularly in the upper part of the tank, and the temperature of the domestic hot water, especially at the point of use. Furthermore, it is designed to control the pumps of the multifunctional storage system, particularly the domestic hot water charging pump and any optional additional pumps.

[0008] A multi-zone stratified storage tank with buffer storage and integrated domestic hot water preparation is known from DE 10 2010 028 198 A1. Such a heating system uses a heat pump as a heat source to heat the storage medium in the storage tank. The storage medium exhibits temperature stratification, which should be disturbed as little as possible during operation of the multi-zone stratified storage tank. Other heat sources for buffer heating systems are also known. The domestic hot water preparation system in such a multi-zone stratified storage tank operates on a flow-through counterflow principle and comprises a tubular, usually coiled, domestic hot water pipe, which serves as a heat exchanger surface and is made of a corrosion-resistant material. The domestic hot water pipe is surrounded by a flexible, temperature- and pressure-resistant flow line in such a way that an annular flow gap is created.The flow gap opens into the buffer storage tank, at least at the top, and in this design, open at both ends, with a distance to the upper and lower walls of the storage tank. This allows the storage medium to flow through the gap using a top-pump or, alternatively, bottom-pump charging pump, and thus come into thermal contact with the domestic hot water line. In alternative designs, if the lower end of the flow gap does not open into the buffer storage tank, it is fluidically connected to the lower part of the storage volume, for example, by means of a pipe loop (DE 298 16 006 U1, DE 10 2009 026 420 A1).

[0009] In the multi-zone stratified storage tank of DE 10 2009 026 420 A1, the storage volume is also divided into the lower, temperature-stratified buffer storage zone and the hot water charging zone above it. A heat pump is used as the heat source, its refrigerant being circulated through the storage tank via a coiled pipe, heating the storage medium according to the desired temperature stratification. The charging pump generates the flow of the medium in the flow gap against the flow direction of the domestic hot water by feeding warm water from the upper, hotter area of ​​the hot water charging zone into the upper area of ​​the flow gap.

[0010] The heat exchanger surface of the counterflow domestic hot water heater is designed for optimal heat transfer between the storage medium flowing in the flow gap and the domestic hot water flowing in the domestic hot water pipe, for example by the choice of material of the heat exchanger surface, the coiling of the pipes and by suitable structuring that increases the surface area and / or other known designs of the heat exchanger surface.

[0011] Such multifunctional storage systems are increasingly designed to be bivalent. In energy generation, the term bivalent refers to the combination of two different heat energy generators for heating domestic hot water and / or space heating.

[0012] The well-known bivalent solutions, whenever heat is supplied from the heat source via district heating, heat pumps, or solar thermal collectors, are characterized by relatively high manufacturing costs and still relatively low efficiency. This low efficiency results from the operating temperatures of over 60°C required for domestic hot water heating for hygienic reasons. Furthermore, every time domestic hot water is drawn, the heating system must frequently provide heat to bring the fluid in the storage tank to the temperature required for domestic hot water heating and, if applicable, space heating.

[0013] To reduce the relatively high cycling frequency of the heating system, screw-in heating elements are increasingly being integrated into the storage tank. These can be powered by a photovoltaic (PV) system and serve as an additional heat source for heating the storage medium. For example, EP 3812678 A1 describes such an electric heating element, also commonly referred to as an electric cartridge or E-cartridge, which protrudes into the cylindrical flow pipe surrounding the coiled domestic hot water pipe to heat the medium within the flow pipe.

[0014] Electric cartridges are generally known as current-carrying heating coils, whose basic form is essentially rod-shaped, but which can also have other shapes suitable for the purpose of the invention. The heating coil can have a thermally conductive coating. A wide variety of designs are known to those skilled in the field of heating technology.

[0015] To generate the necessary energy for heating the storage medium, numerous electric heating elements are sometimes integrated. These are operated at different power levels according to the specific heat energy demand and are integrated into the layer of the buffer storage tank corresponding to their power output. While such a solution allows for a reduction in the energy supplied by the heating system, particularly during the warmer and more sunny months, and replaces it with solar energy, the technical complexity of the heating elements and their control system, as well as the associated impact on the stratification within the storage tank, negatively affects the overall efficiency.

[0016] The object of the invention is therefore to provide an advantageous concept suitable for reducing the manufacturing and operating costs of multifunctional storage systems for heat pumps, district heating and other heat sources with hot water preparation, and for improving efficiency.

[0017] Furthermore, it is desirable to increase the utilization of the solar energy of a photovoltaic (PV) system of the operator of the multifunctional storage system and to use the PV surplus as much as possible by the operator itself.

[0018] The problem is solved with a bivalent multifunctional storage system according to the main claim and a method for operating such a multifunctional storage system according to claim 8: Preferred embodiments of the invention are formulated in the dependent claims relating thereto.

[0019] With regard to the invention, the term "bivalent multifunctional storage system" comprises a primary heat generator, which provides at least the base load and, in the event that the secondary energy source is temporarily unable to supply energy, all of the energy, and at least one electric heating element, which is powered by a photovoltaic system. The primary heat generator can be, for example, a combustion boiler, district heating system, or another type of heat generator.

[0020] The problem is solved by the subject matter of claim 1, wherein the multifunctional storage system comprises the following components: a multi-zone stratified storage tank with a storage container for receiving the storage medium, an external heat source which is connected to the multi-zone stratified storage tank for heating storage medium located in the storage container, wherein the multi-zone stratified storage tank comprises devices for forming a stratified charge generated by different temperatures of the storage medium such that a hot water charge zone is formed above a buffer storage zone, such that the temperature of the storage medium increases with increasing height in the storage container;a counterflow domestic hot water heater, which runs at least partially through the hot water charging zone, wherein the counterflow domestic hot water heater has a coiled domestic hot water pipe designed as a heat exchanger surface, the domestic hot water outlet of which is located above its domestic hot water inlet, and a flow pipe concentrically enclosing the domestic hot water pipe such that a flow gap is formed between the two pipes, wherein the upper inlet and the lower outlet of the flow gap open into the storage medium; wherein the inlet of the flow gap has a distance A to the uppermost inner termination of the tank wall;A domestic hot water charging pump, designed for charging the flow gap with storage medium, the suction side of which is fluidically connected to the upper region of the storage tank volume located above the inlet of the flow gap and the pressure side of which is fluidically connected to the inlet of the flow gap; a control unit, designed and configured for operating the multifunctional storage system; at least one electric cartridge, here also referred to as E-cartridge, the heating surface of which is arranged in a heating zone within the hot water charging zone for heating the storage medium, at a distance E, measured from the uppermost inner end of the tank wall of the storage tank to the lower edge of the heating surface of the E-cartridge, the heating zone extending at most to the eighth coil of the domestic hot water pipe.

[0021] Various known storage types can be used as multifunctional storage units according to the invention. A buffer storage unit is known from DE 10 2010 028 198 A1, as described above in the prior art. In DE 10 2009 026 420 A1, the buffer storage zone and the hot water charging zone are decoupled from each other by a perforated separating disc with an annular gap. Reference is made herein to both applications in their entirety.

[0022] For domestic hot water heating according to the invention, at least one electric cartridge is integrated in the upper, hot heating area of ​​the hot water charging zone, without protruding into the flow gap in which the domestic hot water is heated by means of the storage medium flowing from top to bottom.

[0023] According to the invention, the heating zone, in which the electric heating element heats the storage medium beyond the usual temperature stratification, is located in the upper part of the storage tank. The additionally heated storage medium is pumped into the inlet of the flow gap, where the domestic hot water is already significantly heated, and receives an additional temperature boost both in the flow gap and above it. This reduces the primary energy required for the multifunctional storage system, in particular the cycling of the heating system for domestic hot water heating. Despite the additional heating of the storage medium in the heating zone, the temperature stratification below is not affected or only minimally affected, since the heated storage medium is pumped directly into the flow gap and thus the additional energy of the electric heating element is primarily used for domestic hot water heating.

[0024] According to the invention, such electric heating elements can be used which, as described below, can be placed in the hot water charging zone and operated at the proposed power output. Their power output can be fixed, adjustable in steps, or modulated (continuously adjustable), with an automatic temperature limiter serving to protect the heating element. The heating surface of the at least one heating element extends into the storage medium through an opening provided for this purpose in the wall of the storage tank.

[0025] The distance of the E-cartridge to the upper wall of the storage tank is hereinafter referred to as E, measured from the highest inner point of the tank wall to the lowest point of the heating surface of the E-cartridge. The distance of the upper inlet of the flow gap from said highest point of the storage tank wall is referred to as A, where A is measured to the lowest point of the opening in the wall of the flow line at its inlet.

[0026] According to the invention, the heating area extends at most to the eighth coil of the domestic hot water pipe, optionally to the seventh, sixth, fifth, fourth, third, or second coil. The coils of the domestic hot water pipe are always counted from the top of the storage tank downwards. The uppermost inner edge of the tank wall also serves as a reference point for measuring the distances A for the inlet of the flow gap and E for the lower edge of the heating surface of the E-cartridge located in the storage medium.

[0027] The reference to the lower edge of the heating surface of the electric cartridge serves solely to clearly define the heating area for the purpose of describing the invention and is not suitable for capturing the thermal area that is actually influenced by the one or more electric cartridges in the hot water charging zone. If the lower boundary of the hot area, as defined, is of little or no significance for the aspect described in each case, this area will subsequently also be referred to as the "hot area".

[0028] The arrangement "between the coils" means that the E-cartridge in question is inserted horizontally between two adjacent coils within this area, with deviations from the horizontal position possible depending on the distance between the coils. For example, at least one E-cartridge is inserted between the second and third, the third and fourth, or the fourth and fifth coils, etc. If several E-cartridges are used for domestic hot water heating according to the invention, they can be distributed around the circumference between the same coils or between different coils within the specified area, optionally also distributed around the circumference.

[0029] It has been found that by positioning the electric heating element in the aforementioned heating zone of the storage tank, extending to the eighth coil of the domestic hot water pipe (counting from the top), and within the hot water charging zone, the domestic hot water can be heated effectively to the required temperature with minimal impact on the temperature stratification of the storage medium. If the hot water charging zone is shortened, the electric heating element must apparently be positioned higher than the eighth coil.

[0030] According to one embodiment of the invention, the control unit is designed and configured to operate the multifunctional storage system, in particular the at least one electric cartridge, using energy from an external photovoltaic system (PV system), preferably its surplus PV energy. PV surplus refers to that portion of solar energy generated by a PV system which cannot be used by the operator of the PV system and is therefore fed into the grid.

[0031] For this purpose, the electric heating element is at least communicatively connected to the PV system and configured for a power range, for example, up to a five-figure wattage. This power range is suitable for current PV systems to utilize solar energy, and in particular the PV surplus, for domestic hot water heating. Depending on the size of the storage tank, the volume of regular domestic hot water consumption, and the output of the PV system, other adjustable power ranges may be necessary. Future developments in PV systems and electric heating elements may also lead to the availability of other adjustable power ranges. The output of the electric heating element can be constant, modulated, or adjustable in steps across the usable power range, ensuring that the power available from the PV surplus is optimally utilized to meet the energy requirements for domestic hot water heating.Continuous control from 0 to 100% of the available power range is possible, for example, using pulse width modulation.

[0032] The same applies to the use of multiple electric heating elements (E-elements), which can have the same or different power outputs or power ranges, depending on the power generated by the PV system or required due to domestic hot water consumption. Cascading E-elements, i.e., connected in series, can be used and switched on sequentially. Staged E-elements, used according to the current situation, are also possible. The power outputs and / or power ranges can be coordinated in such a way that the available PV surplus can be optimally used for domestic hot water heating.

[0033] For example, the control unit includes an energy meter or is connected to one. An energy meter is designed and configured to determine the energy surplus available from the PV system by comparing it to the preset feed-in energy. The energy meter can also be configured to establish the communication link between the electric heating element and the external PV system. It controls or regulates at least one or more electric heating elements depending on the power required to achieve the desired domestic hot water temperature and / or depending on the available PV surplus. An energy meter is known as a device for measuring electricity consumption and is connected to the electric heating element via a cable or wireless connection for its control, so that the power output of the electric heating element can be adjusted to the available and measured PV surplus.Furthermore, the energy meter can be configured to receive measured values ​​from the E-cartridge, such as the temperature at the heating coil, the set safety temperature limit, and the temperatures at other measuring points in the storage medium, and to evaluate them based on predefined parameters.

[0034] The arrangement of at least one or more electric heating elements (E-elements) in the heating section depends on various parameters of the storage tank and the counterflow domestic hot water heater, such as the volume and diameter of the storage tank, the width of the flow gap, the pitch of the coil, the temperature stratification of the storage medium, and others. It has proven advantageous to arrange the E-element below the open outlet of the flow gap. This variant is characterized in that the distance E, defining the position of the E-element, is greater than the distance A, defining the position of the upper inlet of the flow gap. In this embodiment, the coils running directly adjacent to the E-element are enclosed by the flow line. A coil is considered to be arranged directly adjacent to the E-element if it lies immediately next to the E-element in a side view.A helix is ​​generally considered to be a section of a coiled pipe which forms a full circle in a top view.

[0035] It has been found that by arranging the E-cartridge below the inlet of the flow gap, a trouble-free operation of the domestic hot water heating system according to the invention can be ensured. The E-cartridge can transfer more heat energy to the surrounding storage medium and is not at risk of overheating.

[0036] In another embodiment, the multifunctional storage system includes an additional pump with a pumping direction opposite to that of the domestic hot water charging pump. Its pressure side is fluidically connected to the hot storage medium in the heating zone of the storage tank, while its suction side is connected to the inlet of the flow gap, which is also located in the upper heating zone. In other words, the suction and pressure sides of this additional pump are reversed compared to the domestic hot water charging pump during its previously described normal operation. This pump is referred to as the stratified charging pump. The stratified charging pump pumps storage medium from the lower, colder zone of the storage tank through the flow gap into the heating zone, where it mixes with the storage medium already there, which has been additionally heated by an electric heating element.This measure also serves to protect the E-cartridge, which is consequently surrounded by storage medium if a predefined temperature limit is exceeded. This storage medium has a lower temperature than the storage medium in the heating section.

[0037] Alternatively or additionally, the suction side of the stratified charging pump can be directly connected to the lower section of the storage tank via a bypass line, pumping cooler storage medium into the heating zone. Optionally, in this embodiment as well, the storage medium can be introduced into the uppermost section of the storage tank or into a lower section of the heating zone.

[0038] The stratified charging pump can be arranged in series with the domestic hot water charging pump, in which case pumps capable of handling opposing flows must be used. Otherwise, using one of the series-arranged pumps would destroy the second pump. Alternatively, both pumps can be integrated into a single pump with reversible flow direction.

[0039] To control the pumps, temperature sensors can be arranged in various suitable positions, for example in the uppermost and optionally lower area of ​​the storage tank, as well as in the domestic hot water outlet or at other positions.

[0040] According to one embodiment, at least one further electric cartridge can be arranged in a deeper region of the storage tank where the stratification exhibits a significant temperature difference to both the uppermost and lowermost layers, particularly in a middle section of the storage tank, for example, in the buffer storage zone. A distance of more than one coil from the electric cartridge in the hot water charging zone, where several electric cartridges are located below the lowest one, is also advantageous. A distance of two, three, four, five, or more coils is preferred, depending on the size of the storage tank and the number of coils, as well as its temperature stratification. The further, lower electric cartridge can be cascaded or operated separately from the first, i.e., the upper electric cartridge described above; for example, this electric cartridge can be operated in an energy range that is higher than that of the upper electric cartridge.It can optionally be adjustable in stages. The lower electric heating element then heats a middle or lower layer of the storage tank, providing a base load. Depending on the hot water demand, the upper electric heating element can be modulated to supplement this base load as needed. Optionally, the upper electric heating element can also be switched off completely.

[0041] Such a cascaded arrangement with appropriately adapted control ranges and cascaded operation is also possible when using more than two stacked E-cartridges. The multiple E-cartridges can be controlled individually or together, and can also be grouped together.

[0042] The control unit of the multifunctional storage system can be configured for automatic or manual control and regulation of the system's processes, such as monitoring the temperature of the storage medium and the domestic hot water at various points in and around the storage tank, temperature regulation, creating counterflow in the flow gap, determining the available PV surplus, and other, even subordinate, processes. In addition to temperature sensors, the multifunctional storage system includes further electronic components for this purpose, such as signal converters, flow switches for controlling the pumps, and other components, as well as hydraulic components such as pumps, valves, buffer tanks to absorb potential pressure surges resulting from switching operations, and other components.

[0043] The operation of one or optionally several electric heating elements using the PV surplus, as well as their control to optimize the self-consumption of solar power, of the PV system linked to the heating system and the multifunctional storage unit, can be carried out wirelessly on the basis of the temperature sensors.

[0044] In conjunction with the previously described embodiments of the multifunctional storage system, the problem is solved procedurally by its operation, wherein the E-cartridge(s) is supplied by that portion of solar energy from a PV system of the heating operator which is not usable by the operator himself and would therefore have to be fed into the public electricity grid ("surplus solar energy" or "PV surplus"), but can be effectively used with the method according to the invention for operating the domestic hot water heating.

[0045] The inventive method for operating the previously described multifunctional storage system comprises the following features: In the storage tank, a stratified charge of the storage medium (3) is created in a known manner by means of an external heat source and devices described therein, resulting from different temperatures of the storage medium (3). The temperature of the storage medium decreases from top to bottom, forming a buffer storage zone and a hot water charging zone above it. Furthermore, the domestic hot water is heated by means of the counterflow domestic hot water heater in the multi-functional storage system. The domestic hot water is directed from bottom to top in the domestic hot water pipe, and the storage medium of the storage tank is pumped from top to bottom through the flow gap, at least in the area of ​​the hot water charging zone, by means of the domestic hot water charging pump. This domestic hot water heating also takes place in accordance with the prior art.An upper heating area of ​​the hot water charging zone, from which the storage medium is pumped into the flow gap, is heated by means of at least one electric heating element.

[0046] The inventive method is based on the concept of additionally heating the storage medium in the uppermost area of ​​the storage tank, the heating zone described above, which is associated with the hot water charging zone, by means of an electric heating element located there, above the temperature typical and required for the storage medium, and then pumping it into the inlet of the flow gap by means of the domestic hot water charging pump. In this way, the domestic hot water pipe near its outlet from the storage tank is heated to a temperature significantly higher than that achievable by the regular temperature stratification of the storage medium in the storage tank due to the operating principle of the multifunctional storage system described above. A reduction in temperature stratification, at least in the buffer storage zone, can be avoided or is possible without lowering the temperature of the domestic hot water below the required level.The operating cycle of the heat source of the multifunctional storage system and the energy demand of the heat source can be significantly reduced.

[0047] In one embodiment of the method according to the invention, the at least one electric cartridge is powered by electricity generated by an external photovoltaic system (PV system). Due to the use of energy from a photovoltaic system, preferably a PV system belonging to the operator of the multifunctional storage system, to power the electric cartridge, the heat input from the heat source to the entire storage medium can be further reduced. This is achieved in such a way that the stratification is not only minimally affected despite domestic hot water withdrawal, such that energy from the heat source is only required when larger quantities of domestic hot water are drawn. Furthermore, the quantity at which an energy input from the heat source becomes necessary can be influenced by the configuration and operation of the one or more electric cartridges.

[0048] According to the invention, the storage medium in the upper region of the hot water charging zone, which is the uppermost region in the storage tank and is also referred to here as the heating zone, is heated and pumped into the flow gap at the inlet of the counterflow heat exchanger located there, where it comes into direct thermal contact with the heat exchanger surface of the domestic hot water line. As a result, the domestic hot water, which flows through the heat exchanger in the opposite direction, from bottom to top, and has therefore been preheated, is heated most intensively in the upper section of the heat exchanger.

[0049] The additional heat energy is supplied by means of one or more electric heating elements, the electric heating elements being powered by electricity from the external photovoltaic (PV) system. According to one embodiment of the invention, this is the PV system of the operator of the multifunctional storage system, whereby its surplus PV power can be used for the additional heating of the storage medium.

[0050] The electric heating element operates within a power range that allows even low output from the photovoltaic system, particularly excess PV power, to be utilized. Currently, this range extends up to a five-figure wattage, but this may change in the future with the further development of the heating and PV systems used. Depending on the design of the single or multiple electric heating elements, the optimal usable power can be achieved through control, for example, via pulse width modulation, or by adjusting at least one electric heating element, or by switching additional electric heating elements on or off. This is based on temperature measurements in the storage tank and / or the extracted domestic hot water.

[0051] According to the invention, an energy meter is used to optimize the utilization of the available PV power. This meter is connected to the electrical distribution board of the house in which the multifunctional storage system is installed and determines the currently available PV surplus from the PV system. The power output of one or more electric charging cartridges is then adjusted to this determined value.

[0052] In further embodiments, when using multiple E-cartridges, the option of combining the, optionally variable, power ranges of the E-cartridges is available. For example, the E-cartridges can be operated in several stages of the same or different power output, or in cascading stages, within the domestic hot water charging zone or within the domestic hot water charging zone and the buffer storage zone. This latter distribution of E-cartridges, for instance, supports the maintenance of temperature stratification in the storage tank, as this can be influenced in the various situations described here regarding the use of the storage medium for adjusting the temperature of the domestic hot water and the heating zone.

[0053] In the event that sufficient PV power is available to heat the storage medium in the heating section to such an extent that its temperature exceeds a predefined target temperature, a further embodiment of the method involves pumping storage medium from a lower section of the storage tank, whose temperature is lower than the target temperature, into the heating section using the stratified charging pump described above, at least until the target temperature is undershot. The colder storage medium can optionally be supplied through the flow gap or via a bypass line, which can optionally run outside the storage tank, independent of the temperature stratification. In another embodiment, the colder storage medium can be pumped by the domestic hot water charging pump by connecting both pumps in series. A combination of both embodiments is also possible.

[0054] In the first case, storage medium is drawn from the lower region where the outlet of the flow gap is located. This region is defined by the system and comprises storage medium at a relatively low temperature, relative to the available temperature layers of the multifunctional storage system. The counterflow in the flow gap is reversed to supply the colder storage medium. Due to the preferably undisturbed or only minimally disturbed temperature stratification, the target temperature can be set solely by adjusting the amount of storage medium supplied.

[0055] In the second case, the multifunctional storage system includes one, or optionally several, bypass lines that lead from at least one cooler area of ​​the storage medium, located below the heating zone, into the heating zone, either inside or outside the storage tank. The use of multiple bypass lines, each accessing different temperature layers, allows the temperature of the supplied storage medium to be varied.

[0056] A further advantage of the invention lies in the possibility of retrofitting existing multifunctional storage systems with one or more electric heating elements (E-elements) for the purpose of utilizing excess PV energy. Such integration of at least one E-element apparently also includes its control, whereby the existing temperature and pressure sensors can be used for this purpose and, if necessary, supplemented by further sensors. Furthermore, the integration is supported by the available energy meters, which can be connected to the house's electrical distribution system and, based on the thus possible determination of the available PV surplus, can control the E-element(s) either via a wired or wireless connection.

[0057] In summary, the following advantages can be achieved with the multifunctional storage system according to the invention and its operating method: The required operating temperature for domestic hot water can be achieved without drawing heat from the heat generator, such as the heating system. At the very least, the amount of heat supplied by the heating system can be significantly reduced. By configuring the number and position of the electric heating elements, their power ranges, and controls, the multifunctional storage system can be adapted to a wide range of demand. In particular, excess PV power from a photovoltaic system can be optimally utilized for domestic hot water heating. Disruptions to temperature stratification, at least in the buffer zone of the storage tank, can be prevented or at least significantly reduced in various ways. The components for implementing this process can be integrated into existing systems.

[0058] The invention will be explained in more detail below with reference to exemplary embodiments. A person skilled in the art would expediently combine the features implemented previously and subsequently in the various embodiments of the invention in further embodiments, insofar as the respective requirements for the multifunctional storage system require and permit. The accompanying figures show in Fig. 1 a first embodiment of the multifunctional storage system with an electric cartridge in the heating area, and Fig. 2 a second embodiment of the multi-function storage system according to Fig. 1 with another electric cartridge in the buffer storage zone.

[0059] The figures represent the invention only schematically and to the extent necessary for understanding it. They do not claim to be complete or to scale. For example, the external energy source is not shown, and the coils of the counterflow domestic hot water heater are enlarged, thus limiting the number of coils of the pipes that can be shown and the positions of the E-cartridges between the coils that can be shown.

[0060] Fig. 1 Figure 1 shows a multifunctional storage system 1 with a storage container 2 filled with a storage medium 3. A temperature stratification is created and maintained within the storage medium 3, with the temperature increasing from bottom to top. The temperature profile from lower to higher temperatures is shown in Fig. 1This is represented by an increasing shade of gray on the surface of the storage tank 2. Temperature stratification creates a buffer storage zone 5 in the lower area and a hot water charging zone 6 in the upper area of ​​the storage tank 2, whereby a sharp separation between the two zones is neither present nor required. The optional version with a perforated separating disc 9 is shown, which has a circumferential annular gap (not shown) to the wall of the storage tank 2.

[0061] Inside the storage tank 2, a counterflow domestic hot water heater 10 is installed, which in the illustrated embodiment runs through the buffer storage zone 5 and the hot water charging zone 6. This heater comprises a domestic hot water pipe 11 designed as a heat exchanger surface 11, the domestic hot water outlet 13 of which opens from the top of the storage tank 2, and the domestic hot water inlet 12 of which is located at the bottom of the storage tank 2. Optionally, the counterflow domestic hot water heater 10 can also be shortened by arranging the domestic hot water inlet 12 and the outlet 17 of the flow gap 15 higher than shown. Additionally or alternatively, the inlet 16 of the flow gap 15 can also be in a different position. In the illustrated embodiment, it is located approximately half a turn of the domestic hot water pipe 11 below its upper passage through the wall 4. However, the counterflow domestic hot water heater 10 runs at least through the hot water charging zone 6.

[0062] The counterflow domestic hot water heater 10 further comprises a flow line 14 that concentrically surrounds the domestic hot water line 11. The flow line 14 is arranged along its entire length such that a flow gap 15 is formed between the two lines. The storage medium 3 is pumped from top to bottom through the flow gap 15 by means of a domestic hot water charging pump 18, the pressure side of which is connected to the upper end of the flow gap 15, its inlet 16. The lower end of the flow gap 15 is therefore its outlet 17. In the exemplary embodiment, the angle of inclination of the coils in the buffer storage zone 5 is chosen to be larger than the angle of inclination in the domestic hot water charging zone 6. Other ratios of the coils and / or the number of coils in both zones are possible.

[0063] In the illustrated embodiment, the inlet of the flow line 14 is located approximately half a turn below the service water outlet 13 from the storage tank 2. Other positions of the inlet 16 and outlet 17 of the flow gap 15 are possible depending on the length of the flow line 14.

[0064] The inlet 16 and outlet 17 of the flow gap 15 open into the storage medium 3. The domestic hot water charging pump 18 is arranged in a bypass line 27 that runs outside the storage tank 1. Its pressure side (the tip of the triangular symbol pointing towards the bypass line) is connected via the bypass line 27 to the inlet 16 of the flow gap 15, and its suction side (the opposite base of the triangular symbol) is connected via the same bypass line 27 to the uppermost wall of the storage tank 2. The domestic hot water charging pump 18 pumps the hottest storage medium 3 located in the uppermost wall of the storage tank 2 into the inlet 16 of the flow gap 14 to heat the domestic hot water to the required temperature.

[0065] The stratified charging pump 19 is arranged in series with the domestic hot water charging pump 18 in the same bypass line 27, but with the opposite pumping direction (represented by the oppositely oriented pump symbol). It pumps colder storage medium 3 through the flow gap 15 from the lower region of the buffer charging zone 5 to the uppermost wall of the storage tank 2. An optional bypass line 27' (shown as a dashed line) leads from the pumps 18 and 19 to an inlet in the buffer storage zone 5 located above the domestic hot water inlet 12.

[0066] In that section of the domestic water line 11 which is not surrounded by the flow line and is therefore heated directly by the storage medium 3 in the storage tank 2, the inlet of the circulation line 8 protrudes, so that its domestic water content is also heated.

[0067] A temperature sensor 22 is arranged in the upper part of the storage tank 2 to measure the temperature of the storage medium 3. Further temperature sensors at other positions are possible to support the, preferably automatic, control of the multifunctional storage system 1. Temperature sensors 22 in the buffer storage zone 5 and in the domestic hot water outlet 13 are shown only as examples.

[0068] An electric heating element 20.1 is arranged between the first coil 25 of the domestic hot water pipe 11 and the third coil 26 of the domestic hot water pipe 11, which is located at a distance from the first coil below it. The rod-shaped heating surface of the electric heating element projects between the two coils 25 and 26. In the illustrated embodiment, E is larger than A, so that the electric heating element 20.1 is arranged in the area of ​​the flow pipe 14. Other ratios of A and E to each other, and consequently other positions between the coils, are possible according to the description above.

[0069] To determine the position of the E-cartridge 20.1 and the inlet 16 of the flow gap 15 in the storage container 2, both points are measured to the highest point of the inner wall of the storage container 2 and can be related to each other on this basis. The distance of the inlet 16 of the flow gap 15 to the uppermost edge of the container wall of the storage container 2 is denoted by A. The lowest point of the heating surface of the E-cartridge 20.1 to the same point on the upper wall is denoted by E. The distance E also determines the size of the "heating area" according to the definition above.

[0070] A control unit 21 automatically or manually controls and regulates the processes of the multifunctional storage system 1, such as temperature measurements, the operation of at least one electric heating element 20.1, the operation of pumps 18 and 19, the determination of the PV surplus using an energy meter 23, and other, including subordinate, processes. The control unit 21 is communicatively connected to the PV system to utilize the energy from the available PV system 24 and to determine the PV surplus.

[0071] The multi-function storage system according to Fig. 2 differs from that of the Fig. 1by means of a further electric heating element 20.2, which is arranged in the buffer storage zone 5 and heats the temperature layer located there to create a base load. In this embodiment, the further electric heating element 20.2 is located between the third and fifth coils of the domestic hot water pipe 11. Other positions and / or multiple electric heating elements within the buffer storage zone 5 are also possible.

[0072] Furthermore, buffer storage zone 5 and hot water charging zone 6 are not separated by a partition. For further details, please refer to the explanations regarding... Fig. 1 referred. Reference symbol list

[0073] 1 Multifunctional storage system 2 Storage tank 3 Storage medium 4 Wall 5 Buffer storage zone 6 Hot water charging zone 7 Heating area 8 Circulation line 9 Dividing disc 10 Counterflow domestic hot water heater 11 Domestic hot water line, heat exchanger surface 12 Domestic hot water inlet 13 Domestic hot water outlet 14 Flow line 15 Flow gap 16 Flow gap inlet 15 17 Flow gap outlet 15 18 Domestic hot water charging pump 19 Stratified charging pump 20.1; 20.2 Electric cartridge 21 Control unit 22 Temperature sensor 23 Energy meter 24 PV system 25 Second turn of domestic hot water line 11 26 Third turn of domestic hot water line 11 27, 27' Bypass line Distance A (top of wall) - bottom edge of flow gap inlet; E (distance) (top of wall) - bottom edge of heating surface (E-cartridge)

Claims

1. Bivalent multifunction storage system designed to generate heat for space heating by means of heat storage in a heat-carrying storage medium heated by an external heat source, and for domestic hot water heating, comprising the following components: - a multi-zone stratified storage device with a storage tank (2) for holding the storage medium (3), - an external heat source connected to the multi-zone stratified storage tank for heating the storage medium (3) located in the storage tank (2), - wherein the multi-zone stratified storage device comprises devices for forming a stratified charge generated by different temperatures of the storage medium (3) in such a way that a hot water charging zone (6) is formed above a buffer storage zone (5) in such a way that the temperature of the storage medium (3) increases with increasing height in the storage tank (2); - a counterflow domestic water heater (10) which runs at least partially through the hot water charging zone (6), - wherein the counterflow domestic water heater (10) has a coiled domestic water pipe (11) designed as a heat exchanger surface, the domestic water outlet (13) of which is located above its domestic water inlet (12), - and a flow pipe (14) concentrically surrounding the domestic water pipe (11) in such a way that a flow gap (15) is formed between the two pipes, - wherein the upper inlet (16) and the lower outlet (17) of the flow gap (15) located below it open into the storage medium (3), and the inlet (16) of the flow gap (15) has a distance A to the upper wall (4) of the storage tank (2); - a domestic water charging pump (18) designed to charge the flow gap (15) with storage medium, the suction side of which is fluidically connected to the upper region of the volume of the storage tank (2) located above the inlet (16) of the flow gap (15) and whose pressure side is fluidically connected to the inlet (16) of the flow gap (15), - a control unit (21) designed and configured to operate the multifunctional storage system (1); characterized in that: - the multifunctional storage system (1) comprises at least one electric cartridge (20.1), hereinafter also referred to as an E-cartridge, whose heating surface is arranged in an upper heating area within the hot water charging zone (6), with a distance E measured from the uppermost end of the wall (4) of the storage tank (2) to the lower edge of the heating surface of the E-cartridge (20.1), - wherein the heating area extends at most to the eighth coil of the domestic water pipe (11).

2. Bivalent multifunction storage system according to claim 1, characterized in that the control unit (21) is designed and configured to operate the at least one electric cartridge (20.1) using the energy from an external photovoltaic system (24).

3. Bivalent multifunction storage system according to claim 2, characterized in that the control unit (21) of the multifunctional storage system (1) comprises an energy meter (23) which is designed to determine a PV surplus available from an external PV system (24) and to adjust the output of the at least one electric cartridge (20.1) to the determined PV surplus.

4. Bivalent multifunction storage system according to one of the preceding claims, characterized in that the distance E is greater than the distance A.

5. Bivalent multifunctional storage system according to one of the preceding claims, further comprising a stratified charging pump (19), the pressure side of which is fluidically connected to the upper region of the volume of the storage tank (2) and the suction side of which is fluidically connected to the inlet (16) of the flow gap (15) and / or the buffer storage zone (5).

6. Bivalent multifunction storage system according to claim 5, characterized in that the domestic water charging pump (18) and the stratified charging pump (19) are connected in series.

7. Bivalent multifunction storage system according to one of the preceding claims, characterized in that the multifunctional storage system (1) has at least one further E-cartridge (20.2) which is arranged in the buffer storage zone (5).

8. Method for operating a multifunction storage system according to one of the preceding claims, - wherein a layer charge of the storage medium (3) is formed in the storage tank (2) by means of said external heat source and by means of said devices, which layer charge is generated by different temperatures of the storage medium (3), with the temperature of the storage medium (3) decreasing from top to bottom, to form a buffer storage zone (5) and an hot water charging zone (6) above it, - wherein the domestic water is heated by means of the counterflow domestic water heater (11) in the multifunctional storage system (1) by the domestic water being conducted in the domestic water pipe (11) from bottom to top and the storage medium (3) of the storage tank (2) is pumped through the flow gap (15) from the upper inlet (16) to the lower outlet (17) of the flow gap (15) by means of the domestic water charging pump (18), characterized in that said upper heating area of the hot water charging zone (6), from which the storage medium (3) is pumped into the flow gap (15), is heated by means of at least one electric cartridge (20.1).

9. Method for operating a multifunction storage system according to claim 8, characterized in that the at least one electric cartridge (20.1) is operated with the electricity, preferably with the PV surplus, which is generated by an external photovoltaic system (PV system) (24).

10. Method for operating a multifunction storage system according to claim 9, characterized in that an energy meter (23) is used to determine the PV surplus available from the external PV system (24) and the power of the at least one electric cartridge (20.1) is adjusted to the determined PV surplus.

11. Method for operating a multifunction storage system according to one of claims 8 to 10, characterized in that several E-cartridges (20.1, 20.2) are operated in several stages of equal power or in cascading stages within the hot water charging zone (6) or within the hot water charging zone (6) and the buffer storage zone (5).

12. Method for operating a multifunction storage system according to claims 8 to 11, characterized in that storage medium (3) is pumped from the inlet (16) of the flow gap (15) and / or from the buffer storage zone (5) of the storage tank (2) into the heating area by means of the stratified charging pump (19).

13. Method for operating a multifunction storage system according to claim 12, characterized in that said storage medium (3) is pumped through the domestic water charging pump (18).

14. Method for operating a multifunction storage system according to one of claims 8 to 13, characterized in that the at least one electric cartridge (20.1) is integrated into the hot water charging zone of an existing multifunctional storage system (1).

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