JP2014169818A - Feedwater heating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heat feedwater to a heat pump as intended in a cycle external heat exchanger so as to improve efficiency of the heat pump, in a feedwater heating system applying the heat pump.SOLUTION: Feedwater to a water supply tank 3 through a water supply passage 8, is successively passed through a cycle external heat exchanger 17, a subcooler 16 and a condenser 13. The cycle external heat exchanger 17 is an indirect heat exchanger between the feedwater to the water supply tank 3 through the water supply passage 8 and a heat source fluid. The subcooler 16 is an indirect heat exchanger between the feedwater to the water supply tank 3 through the water supply passage 8 and a refrigerant from the condenser 13 to an expansion valve 14. The heat source fluid is allowed to pass through an evaporator 15 and the cycle external heat exchanger 17 in parallel.

Description

  The present invention relates to a feed water heating system using a heat pump.

  Conventionally, as disclosed in Patent Document 1 below, a system capable of heating water supplied to a water supply tank (23) of a boiler (24) using a heat pump (12) is known. In addition, the applicant has proposed a feed water warming system in which the efficiency of the heat pump is further improved as compared with this prior art, and has already filed a patent application (Japanese Patent Application No. 2012-79191).

  The pending water heating system includes a heat pump and a water tank, and the water supplied to the water tank via the water supply path includes an external heat exchanger (waste heat recovery heat exchanger), a supercooler, and a condenser. In order. The heat exchanger outside the cycle is an indirect heat exchanger between the water supplied to the water supply tank via the water supply channel and the heat source fluid after passing through the evaporator, and the subcooler is connected to the water supply tank via the water supply channel. It is an indirect heat exchanger between the feed water and the refrigerant from the condenser to the expansion valve. It is preferable to adjust the amount of water flow to the condenser so that the heat pump is operated during water supply to the water supply tank via the water supply path, and the outlet water temperature of the condenser of the heat pump is maintained at the set temperature.

JP 2010-25431 A (FIGS. 2 and 3)

  However, the heat source fluid is passed through the heat pump evaporator and then to the off-cycle heat exchanger. In other words, the fluid for heating the feed water in the off-cycle heat exchanger is used as a heat source for the heat pump and is supplied to the off-cycle heat exchanger after the temperature is lowered. Therefore, there is a possibility that the water supply cannot be sufficiently heated in the external heat exchanger.

  Therefore, the problem to be solved by the present invention is to improve the efficiency of the heat pump by heating the water supplied to the heat pump as desired in the external heat exchanger in the feed water heating system using the heat pump. .

  The present invention has been made to solve the above problems, and the invention according to claim 1 is characterized in that a compressor, a condenser, an expansion valve, and an evaporator are sequentially connected in an annular manner to circulate a refrigerant, and the evaporation. Heat is drawn from the heat source fluid that is passed through the condenser, and the heat pump that heats the water that passes through the condenser, the heat exchanger outside the cycle, the supercooler, and the condenser are passed through in order, and water can be supplied through the water supply channel A water supply tank, and the heat exchanger outside the cycle is an indirect heat exchanger for supplying water to the water supply tank via the water supply path and a heat source fluid, and the subcooler is configured to pass the water supply path. Indirect heat exchanger between the water supply to the water supply tank and the refrigerant from the condenser to the expansion valve, and a heat source fluid is passed in parallel through the evaporator and the off-cycle heat exchanger It is the feed water heating system characterized by this.

  According to the first aspect of the present invention, water supplied to the water supply tank is sequentially passed through the off-cycle heat exchanger, the subcooler, and the condenser, while the heat source fluid includes the evaporator, the off-cycle heat exchanger, Is passed in parallel. In the heat exchanger outside the cycle and the supercooler, the efficiency of the heat pump can be improved by preheating the water supply to the condenser. In addition, since the heat source fluid is passed through the heat exchanger outside the cycle in parallel with the evaporator, the heating amount of the feed water is increased as compared with the case where the heat source fluid after passing through the evaporator is passed in series. be able to.

  Furthermore, the invention according to claim 2 controls the presence or absence of water supply to the water supply tank via the water supply path and the output of the heat pump based on the water level of the water supply tank, and the output via the water supply path. The feed water heating system according to claim 1, wherein the water flow rate is adjusted so that the water temperature on the outlet side of the condenser is maintained at a set temperature during water supply to the water supply tank.

  According to the second aspect of the present invention, the amount of water flow to the condenser (via the water supply channel) is maintained so that the water temperature on the outlet side of the condenser is maintained at the set temperature during the water supply to the water supply tank via the water supply channel. Regardless of the water temperature of the water supply source or the temperature of the heat source fluid, hot water having a desired temperature can be obtained by adjusting the water supply flow rate to the water supply tank.

  ADVANTAGE OF THE INVENTION According to this invention, in the feed water heating system using a heat pump, the feed water to a heat pump can be heated as desired in an external heat exchanger, thereby improving the efficiency of the heat pump.

It is the schematic which shows one Example of the feed water heating system of this invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing an embodiment of a feed water warming system 1 of the present invention.

  The feed water warming system 1 of the present embodiment is a system that can heat the feed water to the feed water tank 3 of the boiler 2 with the heat pump 4. The feed water tank 3 that stores the feed water to the boiler 2, and the feed water tank 3 A replenishment water tank 5 for storing water supply, a heat pump 4 for heating water supplied from the replenishment water tank 5 to the water supply tank 3, and a heat source water tank for storing heat source water (for example, waste hot water) as a heat source of the heat pump 4. 6.

  The boiler 2 is a steam boiler, and heats the feed water from the feed water tank 3 into steam. The boiler 2 is typically adjusted in combustion quantity so as to maintain the desired steam pressure. Moreover, the pump 7 provided in the inside of the water supply path from the water supply tank 3 to the boiler 2, or the boiler 2 is controlled so that the boiler 2 may maintain the water level in a can body as desired. The steam from the boiler 2 is sent to various steam use facilities (not shown), but drain (condensed water of steam) from the steam use facility may be returned to the water supply tank 3.

  The water supply tank 3 can be supplied with water from the make-up water tank 5 via the heat pump 4 through the water supply path 8 and can be supplied through the make-up water path 9 without going through the heat pump 4. By controlling the operation of the water supply pump 10 provided in the water supply path 8 and the makeup water pump 11 provided in the makeup water path 9, via either one or both of the water supply path 8 and the makeup water path 9, Water can be supplied from the makeup water tank 5 to the water supply tank 3.

  In the present embodiment, the feed water pump 10 can control the rotation speed by an inverter. By changing the rotation speed of the water supply pump 10, the water supply flow rate to the water supply tank 3 through the water supply path 8 can be adjusted. On the other hand, the makeup water pump 11 is on / off controlled in this embodiment.

  The makeup water tank 5 stores water supplied to the water supply tank 3. In this embodiment, soft water is used as the water supply to the makeup water tank 5. That is, the soft water from which the water hardness has been removed by the water softener (not shown) is supplied to the makeup water tank 5 and stored. By controlling the water supply from the water softener based on the water level of the makeup water tank 5, the water level of the makeup water tank 5 is maintained as desired.

  The heat pump 4 is a vapor compression heat pump, and includes a compressor 12, a condenser 13, an expansion valve 14, and an evaporator 15 that are sequentially connected in an annular shape. The compressor 12 compresses the gas refrigerant to a high temperature and a high pressure. The condenser 13 condenses and liquefies the gas refrigerant from the compressor 12. Furthermore, the expansion valve 14 allows the liquid refrigerant from the condenser 13 to pass therethrough, thereby reducing the pressure and temperature of the refrigerant. The evaporator 15 evaporates the refrigerant from the expansion valve 14.

  Therefore, in the heat pump 4, the refrigerant takes heat from the outside and vaporizes in the evaporator 15, while the refrigerant dissipates heat to the outside and condenses in the condenser 13. In this embodiment, the heat pump 4 draws heat from the heat source water in the evaporator 15 and heats the water in the water supply channel 8 in the condenser 13.

  It is preferable that the heat pump 4 further includes a supercooler 16 between the condenser 13 and the expansion valve 14. The subcooler 16 is an indirect heat exchanger between the refrigerant from the condenser 13 to the expansion valve 14 and the feed water to the condenser 13. The subcooler 16 can supercool the refrigerant from the condenser 13 to the expansion valve 14 by supplying water to the condenser 13, and can supply the refrigerant to the condenser 13 by the refrigerant from the condenser 13 to the expansion valve 14. The water supply can be heated. The refrigerant of the heat pump 4 preferably releases latent heat in the condenser 13 and releases sensible heat in the subcooler 16.

  That is, in the condenser 13, the gas refrigerant is condensed into a liquid refrigerant, and the liquid refrigerant is supplied to the subcooler 16, and the liquid refrigerant is further cooled (supercooled) in the subcooler 16. By separating heat exchangers for refrigerant condensation and supercooling, the heat exchanger can be easily designed, the heat exchanger can be reduced in size with a simple structure, and costs can be reduced. In addition, a general-purpose heat exchanger can be used.

  In addition, in the heat pump 4, an accumulator is installed on the inlet side of the compressor 12, an oil separator is installed on the outlet side of the compressor 12, or the outlet side of the condenser 13 (the condenser 13 and the subcooler 16 A receiver may be installed between the two).

  By the way, the heat pump 4 may be capable of changing its output. For example, the output of the heat pump 4 can be changed by changing the power supply frequency of the motor of the compressor 12 and thus the rotational speed by an inverter.

  The feed water heating system 1 further includes an external heat exchanger 17. This extra-cycle heat exchanger 17 is an indirect heat exchanger for supplying water to the subcooler 16 and heat source water from the heat source water tank 6. Accordingly, the water in the water supply channel 8 is passed through the cycle heat exchanger 17, the subcooler 16, and the condenser 13 in order. On the other hand, the heat source water in the heat source water tank 6 is passed through the evaporator 15 and the external heat exchanger 17 in parallel. Specifically, the heat source water in the heat source water tank 6 is passed to the evaporator 15 via the first heat source supply path 18 and to the off-cycle heat exchanger 17 via the second heat source supply path 19. The

  The heat source water tank 6 stores heat source water as a heat source of the heat pump 4. The heat source water is, for example, waste hot water (hot water discharged from a factory or the like). The heat source water tank 6 is provided with a heat source water supply path 20 and an overflow path 21 for overflowing a predetermined amount or more of water.

  As described above, the heat source water in the heat source water tank 6 is passed through the evaporator 15 of the heat pump 4 via the first heat source supply path 18, and in parallel with this, via the second heat source supply path 19. , Passed through the external heat exchanger 17. The first heat source supply path 18 is provided with a first heat source supply pump 22 on the upstream side of the evaporator 15, and the heat source water from the heat source water tank 6 is supplied by operating the first heat source supply pump 22. , Can be passed through the evaporator 15. On the other hand, the second heat source supply path 19 is provided with a second heat source supply pump 23 on the upstream side of the external heat exchanger 17, and the heat source water tank 6 is operated by operating the second heat source supply pump 23. The heat source water from can be passed through an off-cycle heat exchanger 17.

  The heat source supply pumps 22 and 23 may be on / off controlled, but may be inverter controlled. In the latter case, the supply flow rate of the heat source water to the evaporator 15 and the external heat exchanger 17 can be adjusted. For example, the first heat source supply pump 22 adjusts the flow rate based on the heat source water temperature on the outlet side of the evaporator 15, and the second heat source supply pump 23 sets the flow rate on the basis of the heat source water temperature on the outlet side of the external heat exchanger 17. You may adjust. Thereby, the discharge temperature of the heat source water can be adjusted as desired.

  In the water supply path 8, a hot water temperature sensor 24 is provided on the outlet side of the condenser 13. The hot water temperature sensor 24 detects the water temperature after passing through the condenser 13. Based on the temperature detected by the hot water temperature sensor 24, the feed water pump 10 is controlled. Here, the feed water pump 10 is inverter-controlled so that the temperature detected by the tapping temperature sensor 24 is maintained at a set temperature (for example, 75 ° C.). That is, the flow rate of water supplied to the water supply tank 3 via the water supply path 8 is adjusted so that the temperature detected by the hot water temperature sensor 24 is maintained at the set temperature. However, in some cases, such flow rate adjustment control by the tapping temperature sensor 24 can be omitted.

  A water level detector 25 is provided in the water supply tank 3. The configuration of the water level detector 25 is not particularly limited. In the present embodiment, the water level detector 25 is an electrode type water level detector. In this case, a plurality of electrode rods 26 to 28 having different lengths are inserted and held in the water supply tank 3 with their lower end portions having different height positions. In the present embodiment, the water supply stop electrode rod 26, the water supply start electrode rod 27, and the load switching electrode rod 28 are inserted into the water supply tank 3 with the lower end portion having a lower height in order. Each electrode rod 26-28 detects the presence or absence of the water level in a lower end part by whether the lower end part is immersed in water.

  The heat source water tank 6 is provided with a water level detector 29 in order to confirm the presence or absence of the heat source water. The configuration of the water level detector 29 is not particularly limited. In the present embodiment, the water level detector 29 is an electrode type water level detector. In this case, the low water level detection electrode rod 30 is inserted in the heat source water tank 6 and it is monitored whether the water level of the heat source water is below the setting. Further, the heat source water tank 6 is provided with a heat source temperature sensor 31 for detecting the temperature of the heat source water.

  Next, control (operation method) of the feed water heating system 1 of the present embodiment will be described. A series of control described below is automatically performed using a controller (not shown).

  Although it is possible to supply water to the water supply tank 3 via the water supply path 8 and also to supply water via the replenishment water path 9, it is preferable to control the water supply via the water supply path 8 to be given priority. For example, the water supply through the water supply channel 8 is controlled so as to maintain the water level of the water supply tank 3 within the set range. However, if the water level of the water supply tank 3 cannot be maintained within the set range, It is preferable to supply water to the water supply tank 3.

  Specifically, in this embodiment, control is performed as follows. Now, when the water supply stop electrode rod 26 detects the water level and the water level in the water supply tank 3 is sufficient, the water supply to the water supply tank 3 is unnecessary, so the water supply pump 10 is stopped and the makeup water pump 11 is also stopped. doing. When the water level in the water supply tank 3 drops due to the water supply from the water supply tank 3 to the boiler 2 and the water supply start electrode rod 27 no longer detects the water level, the water supply pump 10 is activated. Thus, water is supplied to the water supply tank 3 through the water supply path 8, but when the water supply stop electrode rod 26 detects the water level, the water supply pump 10 is stopped. On the other hand, even if the water supply pump 10 is operated, the water level in the water supply tank 3 cannot be recovered, and when the water supply level falls below a predetermined lower supply water start level, the water supply pump 11 is operated to supply water through the supply water channel 9. Supply water to tank 3. Thereby, when the water level of the water supply tank 3 recovers and the water level of the water supply tank 3 exceeds the makeup water stop water level, the makeup water pump 11 is stopped and the water supply via the makeup water channel 9 is stopped. When such control is performed, it is sufficient that the makeup water start water level and the makeup water stop water level can also be detected by the water level detector 25.

  While supplying water via the water supply path 8, the heat pump 4 is operated, and the first heat source supply pump 22 and the second heat source supply pump 23 are operated. The heat pump 4 is switched between operation and stop depending on whether or not the compressor 12 is activated. The output of the heat pump 4 is preferably controlled based on the water level of the water supply tank 3. In this embodiment, when the water level in the water supply tank 3 falls and the water supply start electrode rod 27 no longer detects the water level, the heat pump 4 is operated at a low load, and the water level is not recovered yet, and the load switching electrode rod 28 detects the water level. If not, the heat pump 4 is switched to high load operation. And at the time of water level recovery, if the water supply start electrode rod 27 detects the water level, the heat pump 4 is switched to the low load operation, and if the water supply stop electrode rod 26 detects the water level, the heat pump 4 is stopped. Thus, in the present embodiment, the heat pump 4 is in three positions: high load operation (typically full load operation = 100% output), low load operation (for example, 50% output), and stop (0% output). Be controlled.

  During the water supply via the water supply path 8, the water supply pump 10 is inverter-controlled in rotation speed so as to maintain the temperature detected by the hot water temperature sensor 24 at the set temperature (the hot water temperature set value). As a result, it is possible to supply water to the water supply tank 3 through the water supply path 8 at a higher flow rate during high load operation of the heat pump 4 than during low load operation.

  When the heat pump 4 is operated and water is supplied from the make-up water tank 5 to the water supply tank 3 through the water supply path 8, the water supplied from the make-up water tank 5 is supplied to the heat exchanger 17 outside the cycle, the subcooler 16 and the condenser 13. Is gradually heated and supplied to the water supply tank 3 at a predetermined temperature. Compared with the case where water is circulated between the water supply tank 3 and the heat pump 4 (condenser 13), the water supply is heated by a single pass (once through) from the makeup water tank 5 to the water supply tank 3. The temperature difference of the feed water before and after passing through the heat pump 4 can be secured, and the coefficient of performance (COP) of the heat pump 4 can be improved. Moreover, each heat exchanger can also be comprised compactly.

  Further, during operation of the heat pump 4, that is, water supply to the water supply tank 3 through the water supply path 8, the water temperature of the heat source water tank 6 is monitored by the heat source temperature sensor 31, and the output of the heat pump 4 is adjusted based on the temperature. May be. The higher the temperature of the heat source water as the heat source of the heat pump 4, the lower the output of the heat pump 4. By adjusting the output of the heat pump 4 in consideration of the temperature of the heat source water, the water supply flow rate to the water supply tank 3 via the water supply path 8 can be stabilized regardless of the temperature change of the heat source water.

  Furthermore, when the water level of the heat source water tank 6 falls during the operation of the heat pump 4 and the low water level detection electrode rod 30 no longer detects the water level, the operation of the heat pump 4 is stopped and the heat source supply pumps 22 and 23 are stopped. Therefore, it is preferable to stop the supply of the heat source water to the evaporator 15 and the heat exchanger 17 outside the cycle. Similarly, during operation of the heat pump 4 (that is, during water supply control to the water supply tank 3 through the water supply path 8), if the amount of water supplied through the water supply path 8 falls below the setting, the operation of the heat pump 4 is stopped. While stopping, it is good to stop supply of the heat source water to the evaporator 15 and the heat exchanger 17 outside a cycle by stopping each heat source supply pump 22 and 23.

  During the water supply to the water supply tank 3 through the water supply path 8, the heat source water from the heat source water tank 6 is passed in parallel to the evaporator 15 and the off-cycle heat exchanger 17. Compared with the case where the heat source fluid is passed through the evaporator 15 and the off-cycle heat exchanger 17 sequentially in series, when the heat source fluid is passed through the evaporator 15 and the off-cycle heat exchanger 17 in parallel, a relatively high-temperature heat source Fluid can be passed through the off-cycle heat exchanger 17. Thereby, since the heat exchange amount in the heat exchanger 17 outside the cycle can be increased and the water supply before the heat pump 4 is heated, the power of the compressor 12 is reduced and the efficiency of the heat pump 4 is improved. be able to. Moreover, since the output of the heat pump 4 can be suppressed, the supercooler 16 and the like can be made smaller. Further, when the heat source fluid is passed through the evaporator 15 and the off-cycle heat exchanger 17 in order, the evaporator 15 becomes a pressure loss element, but the heat source fluid is passed through the evaporator 15 and the off-cycle heat exchanger 17 in parallel. In this case, there is an advantage that there is no such pressure loss element.

  The feed water warming system 1 of the present invention is not limited to the configuration of the above embodiment, and can be changed as appropriate. For example, in the said Example, in order to adjust the feed water flow rate to the feed water tank 3 via the feed water path 8, the feed water pump 10 was inverter-controlled, However, The feed water pump 10 was provided in the feed water path 8 while performing on-off control. The opening degree of the valve may be adjusted. That is, if the flow rate of the water supply through the water supply path 8 can be adjusted based on the temperature detected by the hot water temperature sensor 24, the flow rate adjustment method can be changed as appropriate.

  Further, the heat pump 4 is not limited to a single stage, and may be a plurality of stages. When the heat pump 4 has a plurality of stages, adjacent stage heat pumps may be connected using an indirect heat exchanger, or may be connected using a direct heat exchanger (intercooler). In the latter case, an intermediate cooler that receives the refrigerant from the compressor of the lower heat pump and the refrigerant from the expansion valve of the upper heat pump and directly exchanges heat between the two refrigerants is provided. And the evaporator of the upper heat pump. As described above, the multi-stage (multi-stage) heat pump includes a single-stage multi-stage heat pump, a multi-element (multi-element) heat pump, or a combination thereof.

  In addition, if water can be supplied to the water supply tank 3 through the water supply path 8 via the condenser 13 and water can be supplied through the replenishment water path 9 without going through the condenser 13, the specifics of the water supply path 8 and the replenishment water path 9 are specified. The configuration is not limited to the configuration of the above embodiment and can be changed as appropriate. For example, in the above-described embodiment, the water supply channel 8 and the supply water channel 9 are provided in parallel so as to connect the supply water tank 5 and the water supply tank 3, respectively, but one end portion of the water supply channel 8 and the supply water channel 9 ( One or both of the end portion on the make-up water tank 5 side and the other end portion (the end portion on the water supply tank 3 side) may be a common conduit. In other words, one end of the makeup water channel 9 may be provided so as to branch from the water supply channel 8 instead of being connected to the makeup water tank 5, and the other end of the makeup water channel 9 is connected to the water supply tank 3. Instead, it may be provided so as to join the water supply path 8 before the water supply tank 3. When one end portion of the replenishment water channel 9 is provided so as to branch from the water supply channel 8 instead of being connected to the replenishment water tank 5, the water supply pump 10 is provided in the water supply channel 8 downstream from the branching unit, while the replenishment water channel 9 may be provided with a supplementary water pump 11, but a pump is provided only in the common pipe upstream of the branching portion, and the valves provided in the water supply passage 8 and / or the supplementary waterway 9 downstream of the branching portion are opened. By adjusting the degree, the flow rate through the water supply channel 8 and the replenishment channel 9 may be adjusted.

  Moreover, in the said Example, although the supplementary water tank 5 was installed in order to store the water supply to the water supply tank 3, installation of the supplementary water tank 5 may be abbreviate | omitted by the case, and the water supply path 8 and the supplement may be directly from a water supply source. Water may be passed through the water channel 9.

  Moreover, in the said Example, although it was made possible to supply water from the makeup water tank 5 to the water supply tank 3 via the water supply channel 8 and / or the makeup water channel 9, these water supply may be performed directly from a water softener. For example, in FIG. 1, instead of omitting the installation of the water supply pump 10 by connecting the base ends of the water supply channel 8 and the makeup water channel 9 together to the water softener, the opening of an electric valve (motor valve) provided in the water supply channel 8 Instead of adjusting the degree and omitting the installation of the makeup water pump 11, the opening and closing of the electromagnetic valve provided in the makeup water channel 9 may be controlled.

  Moreover, although the said Example demonstrated the system which can heat the water supply to the feed water tank 3 of the boiler 2 with the heat pump 4, the utilization place of the stored water of the feed water tank 3 is not restricted to the boiler 2, and can be changed suitably. is there. In some cases, the replenishment water tank 5 and the replenishment water channel 9 may be omitted.

  Moreover, although the said Example demonstrated the example using heat source water as a heat source of the heat pump 4 (it is also a fluid which heats feed water in the heat exchanger 17 outside a cycle), heat source water is used as a heat source fluid of the heat pump 4. Not limited to this, various fluids such as air and exhaust gas can be used.

  Furthermore, in the said Example, although the compressor 12 of the heat pump 4 was driven by the electric motor, the drive source of the compressor 12 is not ask | required in particular. For example, the compressor 12 may be driven by a steam motor (steam engine) that generates power using steam instead of or in addition to the electric motor, or may be driven by a gas engine. In that case, the output of the compressor 12 can be adjusted by adjusting the amount of steam supplied to the steam motor or the amount of gas supplied to the gas engine.

DESCRIPTION OF SYMBOLS 1 Supply water heating system 2 Boiler 3 Supply water tank 4 Heat pump 5 Supply water tank 6 Heat source water tank 8 Supply water path 9 Supply water path 10 Supply water pump 11 Supply water pump 12 Compressor 13 Condenser 14 Expansion valve 15 Evaporator 16 Supercooler 17 Heat exchanger outside cycle 18 First heat source supply path 19 Second heat source supply path 22 First heat source supply pump 23 Second heat source supply pump 24 Hot water temperature sensor 25 Water level detector

Claims (2)

A compressor, a condenser, an expansion valve, and an evaporator are sequentially connected in an annular manner to circulate the refrigerant, draw up heat from a heat source fluid that passes through the evaporator, and heat water that passes through the condenser When,
An external cycle heat exchanger, a supercooler, and a water supply tank capable of supplying water through a water supply passage through the condenser in order,
The heat exchanger outside the cycle is an indirect heat exchanger between the water supply to the water supply tank via the water supply passage and the heat source fluid,
The supercooler is an indirect heat exchanger between the water supplied to the water supply tank via the water supply passage and the refrigerant from the condenser to the expansion valve,
A feed water heating system, wherein a heat source fluid is passed in parallel through the evaporator and the external heat exchanger. Based on the water level of the water supply tank, the presence or absence of water supply to the water supply tank via the water supply path, and the output of the heat pump are controlled,
2. The feed water heating system according to claim 1, wherein the amount of water flow is adjusted so that the water temperature on the outlet side of the condenser is maintained at a set temperature during water supply to the water supply tank via the water supply path. .

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