Heat pump

Abstract

A heat pump (HEWP) for generating heat, the heat pump (HEWP) having a refrigerant circuit (K) in which a refrigerant is conducted cyclically through a first heat exchanger (1), a compression device (4), a second heat exchanger (2) and an expansion device (5), the first heat exchanger (1) being thermally conductively connectable via a primary heat circuit (PWK) to a primary heat source and via a secondary heat circuit (SWK) to a secondary heat source (SQ), a secondary heat supply from the secondary heat source (SQ) to the first heat exchanger (1) being controllable via a control device (15) which is configured to control the secondary heat supply depending on an evaporation temperature of a process medium, the secondary heat supply being controlled by the control device (15) in such a way that, when the inflow temperature is higher than an evaporation temperature of the refrigerant, all of the secondary heat providable by the secondary heat source (SQ) is given off to the first heat exchanger (1).

Description

[0001] heat pump

[0002] Description

[0003] The invention relates to a heat pump for generating heat, wherein the heat pump has a refrigerant circuit in which a refrigerant is cyclically passed through a first heat exchanger, a compression device, a second heat exchanger and an expansion device, wherein the first heat exchanger can be thermally connected via a primary heat circuit to at least one primary heat source and via a secondary heat circuit to at least one secondary heat source different from the primary heat source, wherein primary heat can be transferred from the primary heat source to the refrigerant via a primary heat medium carried in the primary heat circuit and secondary heat can be transferred from the secondary heat source to the refrigerant via a secondary heat medium carried in the secondary heat circuit.

[0004] Technical background

[0005] Heat pumps for heating systems and hot water production are well-established technologies. Often, ambient air, geothermal and solar thermal energy, or waste heat from industrial processes are used as heat sources for a heat pump.

[0006] In this context, solar thermal energy is typically used to generate hot water and / or to support an existing heating system with a heat pump. However, during the winter months, and even in the transitional seasons, the achievable temperature level of the solar yield is insufficient to ensure the practical use of solar thermal energy as an additional heat source. Therefore, efficient use of such solar thermal systems during the colder months is currently either not possible or only possible to a limited extent.

[0007] It is an object of the invention to overcome or at least improve upon the disadvantages of the prior art. In particular, it is an object of the invention to provide a heat pump which, through the use of various heat sources, specifically improves the efficiency or coefficient of performance of a heat pump and has a simplified design. This object is achieved with a heat pump according to claim 1. Preferred embodiments are described in the dependent claims.

[0008] Brief description of the invention

[0009] According to the invention, the secondary heat supply from the secondary heat medium to the first heat exchanger can be controlled via a control device of the heat pump, wherein the control device is configured to control the secondary heat supply as a function of an evaporation temperature of the process medium (refrigerant), wherein the inlet temperature is the temperature of the secondary heat medium before entering the first heat exchanger, wherein the secondary heat supply is controlled by the control device in such a way that, if the inlet temperature is higher than a maximum permissible evaporation temperature of the refrigerant, all the secondary heat that can be provided by the secondary heat source is delivered to the first heat exchanger.

[0010] The invention disclosed herein enables the improvement of the coefficient of performance (COP) of a heat pump even at low solar yield temperatures (for example, at temperatures below 25°C). Furthermore, the heat pump according to the invention can also simplify its design.

[0011] This offers the advantage that the heat pump according to the invention can be used for a heating system and / or for hot water generation with the additional use of secondary heat sources with a low temperature level, for example, solar thermal energy. Advantageously, for example, when solar yield is low, all available secondary heat (in this case, a certain amount of solar heat) can be directed to the first heat exchanger. Likewise, volatile low-temperature heat, e.g., waste heat from an industrial process or other sources such as geothermal energy or industrial waste heat, can also be used as a secondary heat source.

[0012] In particular, defrosting cycles in air-cooled heat exchangers can be avoided or their frequency significantly reduced by increasing the evaporation temperature of the refrigerant. If defrosting is still necessary, it can be carried out energy-efficiently using solar thermal energy via the multi-media heat exchanger according to the invention (i.e., a heat exchanger that utilizes different heat sources). This eliminates the need for an additional control device for reversing the refrigeration cycle, which in turn simplifies the design of the heat pump.

[0013] The control device may be designed to reduce the secondary heat transferable to the first heat exchanger when a maximum permissible evaporation temperature of the refrigerant is exceeded. This can occur, for example, if the solar yield (and thus the secondary heat provided) exceeds a certain threshold, which is defined by the design-permissible intake temperature of the compressor.

[0014] The control device may be designed to reduce secondary heat by returning a portion of the secondary heat medium to the secondary heat source before it enters the first heat exchanger, via a bypass heat circuit connected to the secondary heat circuit by a bypass valve. This allows for a structurally simple reduction of secondary heat at the first heat exchanger.

[0015] The bypass heat circuit between the bypass valve and the secondary heat source can be designed to include a heat storage unit, whereby the secondary heat medium routed through the bypass heat circuit can be directed either via the heat storage unit or directly to the secondary heat source by means of a diverter valve. This offers the advantage that excess secondary heat can be stored in the heat storage unit.

[0016] It may be provided that the control device is configured to detect the inlet temperature of the secondary heat medium in the bypass heat circuit and the temperature in the heat storage unit, wherein, if the inlet temperature reaches or exceeds the temperature of the heat storage unit, the switching valve is controlled in such a way that the secondary heat medium is returned to the secondary heat source via the heat storage unit.

[0017] It may be provided that secondary heat medium stored in the heat storage unit can be introduced into a section of the secondary heat circuit downstream of the secondary heat source via a defrost valve in order to defrost the first heat exchanger, whereby the secondary heat supply from the secondary heat source to the first heat exchanger is interrupted during defrosting. It may be provided that air, water, or brine is used as the primary heat source, with a solar thermal system preferably being used as the secondary heat source.

[0018] It may be provided that the second heat exchanger is designed as a condenser, which is set up for the liquefaction or condensation of the refrigerant, whereby heat can be transferred from the refrigerant to a heating system that can be connected to the second heat exchanger.

[0019] The second heat exchanger may be provided with an inlet and a return connection for connection to a heating system, the return connection having a temperature sensor designed to detect the return temperature of a heating medium in the heating system. The second heat exchanger is connected to the bypass heating circuit via a tertiary heat circuit, and the control device is configured to direct a portion of the secondary heat medium to the second heat exchanger via the tertiary heat circuit for heat exchange with the heating medium when the inlet temperature of the secondary heat medium exceeds a threshold. In other words, the second heat exchanger can also be designed as a multi-media heat exchanger.

[0020] It may be provided that the expansion device is designed as an expansion valve, which is set up to expand the refrigerant volume.

[0021] It may be provided that the compression device is designed as a compressor, which is set up to compress the refrigerant volume.

[0022] The heat pump may include a first sensor device designed to measure the inlet temperature of the secondary heat medium, and a second sensor device designed to measure the temperature of the secondary heat medium in the heat storage unit.

[0023] It may be provided that the primary heat that can be supplied by the primary heat medium depends on the ambient temperature of the heat pump.

[0024] It may be provided that the first heat exchanger has a first heat exchange chamber and a second heat exchange chamber, wherein the first heat exchange chamber is thermally connected to the primary heat source via the primary heat circuit and the second heat exchange chamber is thermally connected to the secondary heat source via the secondary heat circuit.

[0025] It may be provided that the first heat exchange chamber and a second heat exchange chamber are designed separately from each other.

[0026] It may be provided that the second heat exchanger can be connected to a coolant inlet and a coolant outlet of a cooling circuit in order to operate the heat pump as a cooling system if the primary heat medium includes brine or water.

[0027] Brief description of the characters

[0028] The invention is explained in more detail below with reference to exemplary embodiments, to which, however, the invention is not limited.

[0029] The illustrations show:

[0030] Fig. 1 shows a process flow diagram of a first embodiment of a heat pump according to the invention, with low solar yield;

[0031] Fig. 2 shows the process flow diagram according to Fig. 1 at average solar yield;

[0032] Fig. 3 shows the process flow diagram according to Fig. 1 at high solar yield;

[0033] Fig. 4 shows the process flow diagram according to Fig. 1 during a defrosting process;

[0034] Fig. 5 shows a process flow diagram of a second embodiment of a heat pump according to the invention; and

[0035] Fig. 6 shows a process flow diagram of a third embodiment of a heat pump according to the invention.

[0036] Character description

[0037] Figures 1 to 6 show exemplary embodiments of a heat pump HEWP according to the invention, in different operating states. The heat pump HEWP operates on the basis of the Carnot cycle. First, the individual components of the heat pump and the different process cycles are explained; further below, individual operating states are then explained with reference to Figures 1 to 6.

[0038] The HEWP (high-efficiency heat pump) comprises a first heat exchanger 1 (e.g., an evaporator), a compression device 4 (e.g., a compressor for compressing the refrigerant volume), a second heat exchanger 2 (e.g., a condenser for liquefying or condensing the refrigerant), and an expansion device 5 (e.g., an expansion valve for expanding the refrigerant volume). The first heat exchanger 1 is designed as a multi-media heat exchanger. The second heat exchanger 2 can also be designed as a multi-media heat exchanger (see embodiment according to Fig. 5). The first heat exchanger 1 can be supplied with air on the primary side (see Figs. 1 to 5) or with water / brine (see Fig. 6).

[0039] The HEWP heat pump comprises a refrigerant circuit K in which a refrigerant is cyclically circulated through the first heat exchanger 1, the compression unit 4, the second heat exchanger 2, and the expansion unit 5. As mentioned above, the first heat exchanger 1 is thermally connected via a primary heat circuit PWK to at least one primary heat source (e.g., air, water, or brine; not shown in the figures). During operation, primary heat is transferred from the primary heat source to the refrigerant via a primary heat medium circulating in the primary heat circuit PWK through the first heat exchanger 1. The amount of primary heat available from the primary heat medium depends, for example, on the ambient temperature of the heat pump.

[0040] Furthermore, the first heat exchanger 1 is thermally connected via a secondary heat circuit SWK to at least one secondary heat source SQ, which differs from the primary heat source, via a bypass valve 6. Depending on the ambient conditions of the heat pump, secondary heat is transferred from the secondary heat source SQ to the refrigerant via a secondary heat medium circulating in the secondary heat circuit SWK and through the first heat exchanger 1.

[0041] The flow of the secondary heat medium in the secondary heat circuit SWK can be controlled via the bypass valve 6 and the valves 13A, 14A, and 7. Depending on the valve position (or operating state), the secondary heat medium can be returned either to the first heat exchanger 1, to the second heat exchanger 2, to a heat storage tank 8, or directly to the secondary heat source SQ. A pump 9 circulates the secondary heat medium in the secondary heat circuit SKW.

[0042] The secondary heat input from the secondary heat medium to the first heat exchanger 1 can be controlled via a control device 15 of the HEWP heat pump. The control device 15 is configured (this will be explained in more detail below with regard to the different operating states of the heat pump) to control the secondary heat input as a function of the evaporation temperature of the process medium or the refrigerant. In this context, the inlet temperature is the temperature of the secondary heat medium before it enters the first heat exchanger 1.

[0043] A sensor 11 detects the temperature of the secondary heat medium, a sensor 10 monitors the maximum permissible intake temperature of the compression device 4. A temperature sensor 16 detects a return temperature of a heating medium of a heating system with which the HEWP heat pump can be connected during operation.

[0044] The first heat exchanger 1 can have a first heat exchange chamber and a second heat exchange chamber, wherein the first heat exchange chamber is thermally connected to the primary heat source via the primary heat circuit PWK and the second heat exchange chamber is thermally connected to the secondary heat source SQ via the secondary heat circuit SWK. The first heat exchange chamber and the second heat exchange chamber are fluidically separated from each other.

[0045] Operating conditions

[0046] Fig. 1 shows an operating state of the HEWP heat pump at low solar yield. The bypass valve 6 is in position AB-B (this is also the default position of the bypass valve 6 when the heat pump starts). The sensor 11 detects the temperature of the secondary heat transfer medium. If this temperature exceeds the evaporation temperature of the refrigerant detected by the control device 15, the bypass valve 6 opens gate A and thus supplies the first heat exchanger 1. This raises the evaporation temperature of the refrigerant and improves the coefficient of performance (COP). The maximum permissible intake temperature of the compression unit 4 is monitored by sensor 10. Valve 13A is open.

[0047] Fig. 2 shows an operating state of the HEWP heat pump at medium solar yield, i.e., with increased secondary heat compared to Fig. 1. The control device 15 can now reduce the secondary heat that can be transferred to the first heat exchanger 1 if the inlet temperature exceeds a maximum permissible evaporation temperature of the refrigerant.

[0048] When the maximum permissible evaporation temperature is reached, bypass valve 6 opens gate B, thus reducing the volume flow of the secondary heat medium through the first heat exchanger 1, as a portion of the secondary heat medium is now routed via a bypass heat circuit BWK. The bypass heat circuit BWK is connected to the return line of the secondary heat circuit SWK.

[0049] Simultaneously, the volume flow of the primary heat source is reduced so that maximum energy input is obtained from the secondary heat source SQ. The control device 15 uses sensor data from the sensor medium 10 to control the bypass valve 6 to maintain the maximum permissible evaporation temperature (alternatively, the sensor medium 10 can also directly control the bypass valve 6).

[0050] The sensor 11 detects the temperature of the bypass flow rate (i.e., the portion of the secondary heat transfer fluid that is not routed to the first heat exchanger 1), and the control device 15 compares this with the current storage temperature of the heat storage tank 8, which is detected by a sensor 12. If this temperature is higher than the temperature of the bypass flow rate, the control device 15 switches the diverter valve 7 to position A-AB. The valve 13A is open.

[0051] Fig. 3 shows an operating state of the HEWP heat pump under high solar yield conditions, i.e., with a further increase in secondary heat compared to Fig. 2. In this operating state, the inlet temperature of the secondary heat medium in the bypass heat circuit BWK and the temperature in the heat storage tank (by means of the sensor 12) are measured. When the inlet temperature reaches or exceeds the temperature of the heat storage tank 8, the control device 15 actuates the diverter valve 7 such that the secondary heat medium is returned to the secondary heat source SQ via the heat storage tank 8. Thus, the heat storage tank 8 can be charged with secondary heat.

[0052] Fig. 4 shows an operating state of the HEWP heat pump during a defrost cycle. If defrosting of the first heat exchanger 1 is necessary despite raising the evaporation temperature, this is made possible by utilizing the thermal energy in the heat storage tank 8. During defrosting, secondary heat stored in the heat storage tank 8 is introduced into a section of the secondary heat circuit SWK downstream of the secondary heat source SQ via a defrost valve 14 to defrost the first heat exchanger 1. During defrosting, the secondary heat supply from the secondary heat source SQ to the first heat exchanger 1 is interrupted. For this purpose, valve 13A closes and the defrost valve 14 opens. The bypass valve 6 remains in position AB-A and the diverter valve 7 in position B-AB.

[0053] As an alternative to the inlet or the extraction line from the heat storage tank 8 shown in Fig. 4, these can also be connected in reverse, so that the inlet of the secondary heat circuit SWK is located in the lower area and the extraction line in the upper area of ​​the heat storage tank 8. In various configurations, the diverter valve 7 can also be designed as a multi-way valve and switched according to the required integration of the heat storage tank 8 into the secondary heat circuit SWK.

[0054] Fig. 5 shows a second embodiment in which the second heat exchanger 2 is also designed as a multi-media heat exchanger. In this embodiment (as well as in the other embodiments shown), the second heat exchanger 2 has an inlet connection ZL and a return connection RL for connection to a heating system (not shown). The return connection RL has a temperature sensor 16, which is designed to detect the return temperature of a heating medium in the heating system. The second heat exchanger 2 is connected to the bypass heating circuit BWK via a tertiary heat circuit TWK.

[0055] When the return temperature of the heating medium is at or below the temperature level of the secondary heat medium in the bypass heating circuit (which is detected by the sensor 11), the control device 15 closes the valve 13A and allows the secondary heat medium to flow through the second heat exchanger 2, with the diverter valve 7 remaining in position A-AB. The valve 14A prevents flow when the valve 13A is open. Fig. 6 shows a third embodiment in which the heat pump HEWP is designed as a brine / water unit. The design and operation are analogous to the first and second embodiments, with the exception that the first heat exchanger 1 is not exposed to air. In this operating state, the heat pump can also be configured for passive cooling. For this purpose, the valve 6A in the return line of a heat transfer brine is used, which closes gate A for cooling operation and allows flow to the second heat exchanger 2.

Claims

Patent claims 1. Heat pump (HEWP) for generating heat, wherein the heat pump (HEWP) has a refrigerant circuit (K) in which a refrigerant is cyclically circulated through a first heat exchanger (1), a compression device (4), a second heat exchanger (2) and an expansion device (5), wherein the first heat exchanger (1) can be thermally connected via a primary heat circuit (PWK) to at least one primary heat source and via a secondary heat circuit (SWK) to at least one secondary heat source (SQ) different from the primary heat source, wherein primary heat can be transferred from the primary heat source to the refrigerant via a primary heat medium circulated in the primary heat circuit (PWK) and secondary heat can be transferred from the secondary heat source (SQ) to the refrigerant via a secondary heat medium circulated in the secondary heat circuit (SWK), characterized in thatthat the secondary heat input from the secondary heat medium to the first heat exchanger (1) is controllable via a control device (15) of the heat pump (HEWP), wherein the control device (15) is configured to control the secondary heat input as a function of the evaporation temperature of the process medium, wherein the inlet temperature is the temperature of the secondary heat medium before entering the first heat exchanger (1), wherein the secondary heat input is controlled by the control device (15) such that, if the inlet temperature is higher than an evaporation temperature of the refrigerant, all the secondary heat available from the secondary heat source (SQ) is delivered to the first heat exchanger (1).

2. Heat pump according to claim 1, wherein the control device (15) is configured to reduce the secondary heat that can be transferred to the first heat exchanger (1) when a maximum permissible evaporation temperature of the refrigerant is exceeded.

3. Heat pump according to one of the preceding claims, wherein the control device (15) is configured to reduce the secondary heat by returning a portion of the secondary heat medium to the secondary heat source (SQ) before it enters the first heat exchanger (1) via a bypass heat circuit (BWK) connected to the secondary heat circuit (SWK) via a bypass valve (6).

4. Heat pump according to claim 3, wherein the bypass heat circuit (BWK) between the bypass valve (6) and the secondary heat source (SQ) has a heat storage unit (8), wherein the secondary heat medium guided via the bypass heat circuit (BWK) can be directed either via the heat storage unit (8) or directly to the secondary heat source (SQ) by means of a switching valve (7).

5. Heat pump according to claim 4, wherein the control device (15) is configured to detect the inlet temperature of the secondary heat medium in the bypass heat circuit (BWK) and the temperature in the heat storage unit (8), wherein, when the inlet temperature reaches or exceeds the temperature of the heat storage unit (8), the switching valve (7) is controlled such that the secondary heat medium is returned to the secondary heat source (SQ) via the heat storage unit (8).

6. Heat pump according to claim 4 or 5, wherein secondary heat medium stored in the heat storage unit (8) can be introduced into a section of the secondary heat circuit downstream of the secondary heat source (SQ) via a defrosting valve (14) in order to defrost the first heat exchanger (1), wherein the secondary heat supply from the secondary heat source (SQ) to the first heat exchanger (1) is interrupted during defrosting.

7. Heat pump according to one of the preceding claims, wherein air or water or brine is provided as the primary heat source, wherein preferably a solar thermal system or waste heat from an industrial process is provided as the secondary heat source (SQ).

8. Heat pump according to one of the preceding claims, wherein the second heat exchanger (2) is designed as a condenser, which is equipped for liquefaction or condensation of the refrigerant, wherein heat can be transferred from the refrigerant to a heating system connectable to the second heat exchanger (2).

9. Heat pump according to one of the preceding claims, wherein the second heat exchanger (2) has an inlet connection (ZL) and a return connection (RL) for connection to a heating system, wherein the return connection has a temperature sensor (16) which is configured to detect a return temperature of a heating medium of the heating system, wherein the second heat exchanger (2) is connected to the bypass via a tertiary heat circuit (TWK). heat circuit (BWK) is connected, wherein the control device (15) is configured to direct a portion of the secondary heat medium to the second heat exchanger (2) via the tertiary heat circuit (TWK) for heat exchange with the heating medium when the inlet temperature of the secondary heat medium exceeds the return temperature of the heating medium.

10. Heat pump according to one of the preceding claims, wherein the expansion device (5) is designed as an expansion valve which is configured to expand the refrigerant volume.

11. Heat pump according to one of the preceding claims, wherein the compression device (4) is designed as a compressor which is configured to compress the refrigerant volume.

12. Heat pump according to one of the preceding claims, comprising a first sensor means (11) which is configured to measure the inlet temperature of the secondary heat medium, and a second sensor means (12) which is configured to measure the temperature of the secondary heat medium in the heat storage unit (8).

13. Heat pump according to one of the preceding claims, wherein the primary heat that can be provided by the primary heat medium depends on an ambient temperature of the heat pump (HE-WP).

14. Heat pump according to one of the preceding claims, wherein the first heat exchanger (1) has a first heat exchange chamber and a second heat exchange chamber, wherein the first heat exchange chamber is thermally connected to the primary heat source via the primary heat circuit (PWK) and the second heat exchange chamber is thermally connected to the secondary heat source (SQ) via the secondary heat circuit (SWK).

15. Heat pump according to claim 14, wherein the first heat exchange chamber and a second heat exchange chamber are designed separately from each other.

16. Heat pump according to one of the preceding claims, wherein the second heat exchanger (2) can be connected to a coolant inlet and a coolant outlet of a cooling circuit in order to operate the heat pump (HEWP) as a cooling system when the primary heat medium comprises brine or water.

Images