Heat pump for supplying heat and hot water to a building, method for operating a heat pump and computer program product

Abstract

A heat pump (1) for heating or cooling a building and for supplying the building with hot water is proposed, comprising a refrigeration circuit (8) in which a refrigerant circulates, a first heat exchanger (2) configured for heat exchange with an ambient medium, a second heat exchanger (3) configured for heat exchange with a heating circuit (7), and a third heat exchanger (4) configured to transfer heat from the refrigeration circuit (8) to water contained in a hot water storage tank (5), wherein: - in heating mode, the first heat exchanger (2) acts as an evaporator and transfers heat from the ambient medium to the refrigeration circuit (8), and the second heat exchanger (3) acts as a condenser, extracting heat from the refrigeration circuit (8) and transferring it to a heating circuit (7).and - in a cooling operation, the second heat exchanger (3) acts as an evaporator and transfers heat from the heating circuit (7) to the refrigeration circuit (8), and the third heat exchanger (4) transfers heat from the refrigeration circuit (8) to water contained in the hot water storage tank (5), and the third heat exchanger (4) is arranged in a bypass line (21) of the first heat exchanger (2), and a three-way valve (6) is configured to direct a refrigerant flow completely to the first heat exchanger (2) or the third heat exchanger (4), or to divide it between the first heat exchanger (2) and the third heat exchanger (4).

Description

[0001] The invention relates to a heat pump for supplying a building with heat, cooling and hot water, a method for operating a heat pump and a computer program product.

[0002] The present invention relates in particular to heating systems for buildings that provide heating, cooling and hot water. These systems are to be improved with regard to CO2 emissions.

[0003] Heat pumps are increasingly coming into focus for the heating of buildings, as they enable the use of sustainable energy sources, especially solar energy. Various heat pump systems are known. They all share a refrigeration cycle in which a refrigerant circulates, enabling heat transfer through a phase change. This refrigeration cycle includes at least one primary heat exchanger, which is connected to an ambient heat source and can extract heat from it. A secondary heat exchanger is connected to a heating circuit of the building and / or a system for providing heated domestic hot water. In heating mode, the primary heat exchanger absorbs thermal energy from the ambient heat source and transfers it to the refrigeration cycle, while the secondary heat exchanger removes the thermal energy from the refrigeration cycle and transfers it to a heat transfer medium in the heating circuit or to the domestic hot water.In this respect, during heating operation, the first heat exchanger is an evaporator, in which the refrigerant in the refrigeration circuit evaporates and absorbs heat, and the second heat exchanger is a condenser, which can transfer heat from the refrigeration circuit to a heating circuit and / or drinking or domestic hot water and thus make it usable.

[0004] A significant advantage of heat pumps is their ability to also operate in cooling mode. For this, the second heat exchanger can be configured to absorb heat from the heating circuit, while the first heat exchanger transfers this absorbed heat from the building to the surrounding environment. Surface heating systems (especially underfloor, ceiling, or wall heating) are particularly well-suited for absorbing heat from the building. To provide domestic hot water, the heat pump must switch from cooling mode back to heating mode to absorb ambient heat and transfer it to the hot water supply.

[0005] EP 2 719 956 A1 describes a solution in which heat from cooling operation can be transferred to a hot water storage tank. However, this solution is technically complex and energy-inefficient.

[0006] The unrelated classifications JP H01-306 756 A and JP H03-282 149 A describe heat pumps that comprehensively include a heat storage device designed as a latent heat storage device and containing a storage material that undergoes a phase change to absorb or release heat.

[0007] It is therefore an object of the invention to at least partially alleviate or solve the problems described with reference to the prior art. In particular, a heat pump and a method for operating it are to be provided that enable an energy-efficient supply of hot water. In addition, the invention should require only minor structural modifications compared to a heat pump according to the prior art.

[0008] These problems are solved by the features of the independent claims. Further advantageous embodiments of the solution proposed here are specified in the independent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0009] A heat pump contributes to the heating or cooling of a building and to the supply of hot water. The heat pump comprises a refrigeration circuit in which a refrigerant circulates, a first heat exchanger configured for heat exchange with an ambient medium, a second heat exchanger configured for heat exchange with a heating circuit, and a third heat exchanger configured to transfer heat from the refrigeration circuit to water contained in a hot water storage tank. The third heat exchanger is located in a bypass line of the refrigeration circuit of the first heat exchanger. Furthermore, a three-way valve is configured to (1) direct a refrigerant flow entirely to the first heat exchanger, or (2) direct a refrigerant flow entirely to the third heat exchanger, or (3) split a refrigerant flow between the first and third heat exchangers (with an adjustable ratio).

[0010] The heat pump can be operated in heating mode and in cooling mode, whereby: In heating mode, the first heat exchanger acts as an evaporator and transfers heat from the ambient medium to the refrigeration circuit, and the second heat exchanger acts as a condenser, extracting heat from the refrigeration circuit and transferring it to a heating circuit; in cooling mode, the second heat exchanger acts as an evaporator and transfers heat from the heating circuit to the refrigeration circuit, and the third heat exchanger transfers heat from the refrigeration circuit to water contained in the hot water storage tank.

[0011] The first heat exchanger is designed to extract or transfer heat from an ambient medium (ambient air, groundwater, or groundwater). In heating mode, the first heat exchanger acts as an evaporator, transferring heat from the ambient medium to the refrigerant in the refrigeration circuit, which then evaporates. In cooling mode, it acts as a condenser, transferring heat from the refrigerant in the refrigeration circuit to the ambient medium. The second heat exchanger is designed to transfer heat from the refrigeration circuit to the heating circuit in heating mode, and vice versa in cooling mode. In heating mode, the second heat exchanger acts as a condenser for the refrigerant, and in cooling mode, as an evaporator. Therefore, in heating mode, heat extracted from the ambient medium is transferred into the building, and in cooling mode, heat is removed from the building and transferred to the ambient medium.In the refrigeration circuit, an expansion valve is located between the first and second heat exchangers, and a compressor is positioned opposite it. The expansion valve and compressor can adjust the conditions (pressure, temperature) suitable for the phase change of the refrigerant. The heat pump may include a control unit that regulates and controls its operation.

[0012] All the aforementioned components of the heat pump can be arranged in a single housing, in which case such a heat pump is called a monobloc heat pump. The heat pump can also be designed as a split heat pump, with the first heat exchanger located in an outdoor unit and the second heat exchanger in an indoor unit, and the outdoor and indoor units connected by refrigerant lines. The heat pump can circulate a refrigerant with a low GWP (global warming potential) value, for example, R290 (propane).

[0013] The hot water storage tank serves to supply the building with hot water. A heat pump, for example, typically offers significantly lower heating output compared to a gas boiler, making intermediate hot water storage both sensible and necessary. In conjunction with the use of renewable energy sources that are available depending on the weather, a hot water storage tank offers the possibility of decoupling heat consumption from heat supply.

[0014] The hot water storage tank can be wall-mounted or floor-standing and features a fourth heat exchanger for transferring heat from a heat transfer medium, such as a heating circuit, to the hot water contained within the tank. The hot water storage tank may include a cold water inlet, which could be connected to a water mains supply, and a hot water outlet, which could be connected to a hot water distribution system or a point of use.

[0015] It is proposed to arrange a third heat exchanger in a bypass line of the first heat exchanger. A bypass line, in this context, refers to a line that bypasses the first heat exchanger and is thus hydraulically connected to a supply line and a return line. A three-way valve is installed at the connection point of the bypass line to the supply and / or return line. This three-way valve is designed to be electrically controlled and allows the refrigerant flow from the refrigeration circuit to be: to feed completely past the first heat exchanger to the third heat exchanger, to feed completely past the third heat exchanger to the first heat exchanger, or to divide the flow between the first and second heat exchangers in a predetermined ratio. This predetermined ratio can correspond to the opening position of the three-way valve.

[0016] Thus, the heat pump proposed here enables the transfer and therefore the use of heat transferred from the building or the building air to the heating circuit by transferring it to water in the hot water storage tank via the third heat exchanger.

[0017] According to one embodiment, an intermediate circuit, in which, for example, heating water circulates by means of a circulation pump, can be present, which hydraulically connects the third heat exchanger with the fourth heat exchanger and enables heat transfer from the refrigeration circuit to the hot water storage tank.

[0018] It goes without saying that the hot water storage tank, or the fourth heat exchanger, is also connected to the heating circuit to ensure hot water supply even during heating operation. To enable hot water supply during cooling operation, the first heat exchanger should not be directly connected to the third heat exchanger. A connecting device can be used, positioned at the interface between the third heat exchanger, the hot water storage tank, and the heating circuit. This device is designed to ensure that the hot water storage tank is charged according to demand and depending on the operating mode (heating / cooling).

[0019] According to one embodiment, a first temperature sensor can be located upstream of a branch point in the refrigeration circuit, in the direction of flow during cooling operation, leading to the first and second heat exchangers. The first temperature sensor can be situated between the four-way valve of the refrigeration circuit and the three-way valve of the first branch. Alternatively or additionally, the first sensor can measure the compressor outlet temperature between the compressor and the four-way valve. The first temperature sensor thus enables the determination of the heat flow in the refrigeration circuit and allows for an assessment of whether transferring heat from the refrigeration circuit to the hot water storage tank is possible or advisable. Without this assessment, commissioning the third heat exchanger could result in heat being drawn from the hot water storage tank or transferred from the hot water storage tank to the refrigeration circuit.

[0020] According to one configuration, the heat pump system can include additional temperature sensors used for regulation and control. These temperature sensors can also be connected to the control unit. For example, a temperature sensor can measure the temperature of the potable or domestic hot water contained in the hot water storage tank and transmit this information to the control unit. Other examples of temperature sensors that can be provided include those that detect the outside temperature and / or the temperature of the ambient medium used, one or more room temperatures in the building, temperatures (of the flow and / or return) of one or more heating circuits, etc.

[0021] According to a further aspect of the invention, a method for operating a heat pump described above is also proposed. In cooling mode, heat from the refrigeration circuit is automatically supplied to the hot water storage tank via the third heat exchanger using the three-way valve, based on the temperature of the refrigerant in the refrigeration circuit as measured by the first temperature sensor and the temperature of the water in the hot water storage tank. This process utilizes the heat extracted from the building during cooling mode by transferring it to domestic hot water or process water in a hot water storage tank. In particular, the heat flow resulting from the commissioning of the third heat exchanger to the hot water storage tank can be determined, or parameters can be considered that allow conclusions to be drawn about the resulting heat flow.

[0022] The process can be carried out permanently or continuously, particularly during the operation of a heat pump system. This process enables the efficient charging of a hot water storage tank in a heat pump system, especially during cooling operation.

[0023] The control unit for a heat pump can be configured to carry out a procedure proposed here. For this purpose, the control unit can, for example, include a processor. In this context, the processor can execute the procedure stored in the control unit's memory. The control unit can wirelessly send signals to the wirelessly controllable valves of the consumers and / or to a charging valve for the domestic hot water system. Furthermore, data acquired or required during the execution of a procedure proposed here can be stored in the control unit's memory.

[0024] In addition, a computer program is proposed, comprising commands that cause a computer, for example the control and monitoring unit, to execute a procedure proposed here for operating a heat pump system.

[0025] It should be noted as a precaution that the numerical terms used here ("first", "second", etc.) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described. Where a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or some of the multiple components, but this is not mandatory.

[0026] The details, features, and advantageous designs discussed in connection with the heat pump can also occur in the method and computer program presented here, and vice versa. In this respect, full reference is made to the explanations provided therein for a more detailed characterization of the features.

[0027] This document describes a heat pump and a method for operating it that at least partially solve the problems outlined with regard to the current state of the art. In particular, the heat pump and the method contribute to increasing the energy efficiency of a heat pump and improving comfort in a simple way, as there is no need to switch to heating mode for hot water supply.

[0028] The invention and its technical context are explained in more detail below with reference to the accompanying figure. It should be noted that the invention is not limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts illustrated in the figure and combine them with other elements and findings from the present description. It should be emphasized that the figure, and especially the depicted dimensions, are only schematic. The figures show: Fig. 1 : a heat pump suggested here.

[0029] Fig. 1Figure 1 shows an exemplary and schematic representation of the heat pump 1 proposed here. It comprises a refrigeration circuit 8 in which a refrigerant circulates. A first heat exchanger 2, configured for heat exchange with ambient air 17, and a second heat exchanger 3, configured for heat exchange with a heating circuit 7 with a flow 15 and a return 16, are connected to the refrigeration circuit 8. The heating circuit 7 is pressurized to 1 to 3 bar and includes a circulation pump (not shown) that circulates a heat transfer medium, usually heating water. An expansion valve 10 is arranged between the first heat exchanger 2 and the second heat exchanger 3. A compressor 11 is arranged opposite the expansion valve 10, between the first heat exchanger 2 and the second heat exchanger 3.

[0030] A four-way valve 12 in the refrigeration circuit 8 can switch between heating and cooling modes. In heating mode, the first heat exchanger 2 acts as an evaporator, and the refrigerant absorbs heat of vaporization. In heating mode, the second heat exchanger 3 acts as a condenser, in which the refrigerant condenses and provides heat of condensation that can be transferred to the heating circuit. In cooling mode, the second heat exchanger 3 acts as an evaporator, in which heat from the heating circuit is absorbed by the evaporating refrigerant. This heat can, for example, be extracted from the room air by a surface heat exchanger (ceiling, wall, or floor heating module) and transferred to the heating circuit 7. According to one aspect of the invention, this heat absorbed from the heating circuit 7 during cooling mode can be transferred to the hot water storage tank 5 and thus utilized.

[0031] For this purpose, a bypass line 21 is connected to the refrigeration circuit 8 in cooling mode, with a first branch 22 upstream of the first heat exchanger 2 and a second branch 23 downstream of the first heat exchanger 2, with respect to the flow direction 20 of the refrigeration circuit 8. A three-way valve 6 is arranged in the first branch 22. A third heat exchanger 4 is arranged in the bypass line 21, which acts as a condenser in cooling mode and transfers the condensation heat of the refrigerant to an intermediate circuit 24. The intermediate circuit 24 transfers this heat to the hot water storage tank 5. A circulation pump (not shown) can be arranged in the intermediate circuit 24 for this purpose. A connecting device can be arranged between the third heat exchanger 4 and the hot water storage tank 5, which is connected to the heating circuit 7 and allows heat to be transferred to the hot water storage tank 5 during heating operation.Furthermore, the connecting device 25 ensures that there is no direct connection between the third heat exchanger 4 and the heating circuit 7, thus enabling parallel operation. In cooling mode, the heat flow extracted from the heating circuit 7 by the refrigerant can therefore be transferred to the hot water storage tank 5 via the connecting device 25. In the flow direction 20 of the refrigeration circuit 8, viewed in cooling mode, a first temperature sensor 9 can be arranged upstream of the first branch 22 to measure the temperature of the refrigerant. Alternatively, the first temperature sensor 9 could also measure the outlet temperature of the compressor 11 between the compressor 11 and the four-way valve 12. Additionally, a second temperature sensor 18 can measure the temperature of the ambient medium, here ambient air 17, and a third temperature sensor 19 can measure the temperature of the water in the hot water storage tank 5.It is understood that a large number of other temperature sensors may be present, whose signals are used to control and regulate the refrigeration circuit 8.

[0032] A control unit 13 of the heat pump 1 is configured to regulate and control its operation. For this purpose, the control unit 13 can be connected electronically to the three-way valve 6, the four-way valve 12, the expansion valve 10, the compressor 11, the first heat exchanger 2, the second heat exchanger 3, the third heat exchanger 4, as well as the first temperature sensor 9, the second temperature sensor 18, the third temperature sensor 19, and the connecting device 25. Signals from various sensors, which may be contained in the aforementioned components, can also be transmitted via this electronic connection. A computer program 14 can be stored in the memory of the control unit 13, which causes it to execute a procedure proposed here.

[0033] In this process, the heat flow absorbed from the heating circuit 7 by the second heat exchanger 3 can be transferred to the hot water storage tank 5 by adjusting the three-way valve 6, which directs the refrigerant at least partially to the bypass line 21 and thus to the third heat exchanger 4. Reference symbol list

[0034] 1 Heat pump 2 First heat exchanger 3 Second heat exchanger 4 Third heat exchanger 5 Hot water storage tank 6 Three-way valve 7 Heating circuit 8 Cooling circuit 9 First temperature sensor 10 Expansion valve 11 Compressor 12 Four-way valve 13 Control unit 14 Computer program 15 Flow 16 Return 17 Ambient air 18 Second temperature sensor 19 Third temperature sensor 20 Flow direction cooling circuit 21 Bypass line 22 First branch 23 Second branch 24 Intermediate circuit 25 Connection device

Claims

1. Heat pump (1) for heating or cooling a building and for supplying the building with hot water, comprising a refrigeration circuit (8) in which a refrigerant circulates, a first heat exchanger (2) configured for heat exchange with an ambient medium, and a second heat exchanger (3) configured for heat exchange with a heating circuit (7), a third heat exchanger (4) configured to transfer heat from the refrigeration circuit (8) to water contained in a hot water storage tank (5), wherein the third heat exchanger (4) is arranged in a bypass line (21) of the refrigeration circuit (8) of the first heat exchanger (2), and a three-way valve (6) configured to direct a refrigerant flow completely to the first heat exchanger (2) or to the third heat exchanger (4), or to divide it between the first heat exchanger (2) and the third heat exchanger (4).

2. Heat pump (1) according to claim 1, wherein a first temperature sensor (9) is arranged in a flow direction (20) of the cooling operation of the refrigeration circuit (8) upstream of a branch (22) of the refrigeration circuit to the first heat exchanger (2) and the third heat exchanger (4).

3. Heat pump (1) according to one of the preceding claims, wherein the first heat exchanger (2) is configured for heat exchange with ambient air (17).

4. Heat pump (1) according to claim 2 comprising a control and regulating device (13) which is electrically connected to the first heat exchanger (2), the second heat exchanger (3) and the third heat exchanger (4) and the first temperature sensor (9).

5. Method for operating a heat pump (1) according to claim 4, wherein in cooling mode, heat from the refrigeration circuit (8) is automatically supplied to the hot water storage tank (5) via the third heat exchanger (4) on a demand basis based on the temperature of the refrigerant detected by the first temperature sensor (9) and a temperature of the water in the hot water storage tank (5) by means of the three-way valve (6).

6. Computer program product (14) comprising commands that cause a heat pump (1) according to claim 4 to execute a method for operating a heat pump (1) according to claim 5.

Images