JP3901192B2 - Heat pump water heater - Google Patents

Description

  The present invention relates to a heat pump water heater that is of a variable heating capacity according to a hot water supply load and that can perform a highly efficient defrosting operation.

  Conventionally, there is a variable heat capacity type heat pump water heater as shown in FIG. 3 (see, for example, Patent Document 1). As shown in FIG. 3, the heat pump water heater includes a hot water storage device 101, a heat pump device 102, a heating device 103, and a control device 113. The heat pump device 102 includes a variable capacity compressor 104, a four-way valve 105 that reverses the refrigerant flow direction during defrosting, a refrigerant-to-water heat exchanger 106 that functions as a condenser and heats water in the hot water tank 110, an expansion valve 107, a refrigerant-to-air heat exchanger 108 that functions as an evaporator and absorbs heat from outdoor air to the refrigerant is sequentially connected, and a fan 109 that supplies outdoor air to the refrigerant-to-air heat exchanger 108 is provided. Further, the hot water storage device 101 is sequentially connected to a hot water storage tank 110, a water circulation pump 111 that conveys water at the bottom of the hot water storage tank 110 to the refrigerant-to-water heat exchanger 106, the refrigerant-to-water heat exchanger 106, and the switching valve 112. The heating device 103 forms a circuit that conveys hot water in the upper part of the hot water tank 110 into the room via the switching valve 112 and returns the hot water to the bottom of the hot water tank 110 after heating the room. At this time, the switching valve 112 switches the water flow path according to when the hot water storage device 101 is operating alone, when the heating device 103 is operating alone, or when the hot water storage device 101 and the heating device 103 are operating simultaneously. It has a function. The control device 113 is a heat pump when the hot load of the hot water storage device 101 or the heating device 103 is relatively low during the single heating operation of the hot water storage device 101 according to the amount of remaining hot water in the hot water tank 110, the indoor heating load or the outside air temperature. When the load of the apparatus 102 is small and the load is large as in the simultaneous hot water storage / heating operation of the hot water storage apparatus 101 and the heating apparatus 103, the heat pump apparatus 102 is controlled to operate at the maximum capacity.

For this reason, when the load is relatively small, such as during hot water storage alone operation or during heating single operation, the capacity of the heat pump device 102 can be reduced to reduce noise and reduce power consumption. By operating 102 at the maximum capacity, it is possible to prevent the hot water tank 110 from running out of heat and the capacity of the heating device 103 to be insufficient.
JP 2004-317093 A

However, in the above-described conventional configuration, the defrosting operation is started when the load increases under the outside air temperature condition where the refrigerant-to-air heat exchanger 108 is frosted and the operation of the heat pump device 102 is switched from the small capacity to the maximum capacity. As a result, there is a fear that the heating operation of the heat pump device 102 cannot be performed. As a method for determining the start of the defrosting operation of the heat pump apparatus 102, it is common to use the evaporation temperature of the refrigerant (in this conventional example, the outlet temperature of the refrigerant-to-air heat exchanger 108). That is, the defrosting operation is started when the outlet temperature of the refrigerant-to-air heat exchanger 108 falls below the defrosting start temperature during the boiling operation. Here, since the defrosting start temperature is uniquely determined regardless of the capacity of the heat pump device 102, the evaporating temperature (of the refrigerant-to-air heat exchanger 108 is changed with the shift from the small capacity operation to the maximum capacity operation. The outlet temperature) also falls below the defrosting start temperature, and shifts from the boiling operation to the defrosting operation.

  The present invention solves the above-mentioned conventional problems, and even when the heating capacity of the heat pump device is switched from a small capacity to a large capacity, the heat pump hot water supply capable of continuing the boiling operation without shifting to the defrosting operation. The purpose is to provide a machine.

In order to solve the above-mentioned conventional problems, the heat pump water heater of the present invention is a heat pump circuit in which the refrigerant is circulated in this order by connecting the compressor, the refrigerant side piping of the hot water supply heat exchanger, the expansion valve, and the evaporator in an annular shape. And a hot water storage tank, a stacking pump, and a water side pipe of the hot water heat exchanger are connected in an annular shape, and water in the lower part of the hot water storage tank is heated in the water side pipe of the hot water heat exchanger and then returned to the upper part of the hot water storage tank. A hot water storage circuit, a boiling mode determining means for setting the heating capacity of the heat pump circuit, and a boiling control means for controlling the heat pump circuit and the hot water storage circuit according to the heating capacity set by the boiling mode determining means; includes a defrosting determining means for detecting the start and end of the defrosting operation of the heat pump circuit, and a defrosting control unit of the heat pump circuit, the defrosting determination means based on the temperature of the evaporator It determines the defrosting start conditions, than when the small when heating capacity is large, is to set the temperature of the evaporator to initiate defrosting low.

  Thereby, even when the heating capacity of the heat pump circuit is switched from the small capacity to the large capacity, the boiling operation can be continued without shifting to the defrosting operation.

  By changing the defrosting start condition according to the heating capacity of the heat pump circuit, even when the heating capacity of the heat pump is switched from small capacity to large capacity, the boiling operation should be continued without shifting to the defrosting operation. It is possible to prevent shortage of heat pump capacity and running out of hot water storage tanks. Furthermore, since it is possible to shift to the defrosting operation at an appropriate timing according to the capacity of the heat pump, it is possible to perform a highly efficient operation and to save energy.

1st invention connects the heat pump circuit which has the refrigerant | coolant side piping of the compressor, the hot water supply heat exchanger, the expansion valve, and the evaporator, the hot water storage tank, the lamination pump, and the water side piping of the hot water supply heat exchanger. A hot water storage circuit for heating the water in the lower part of the hot water storage tank in the water-side piping of the hot water supply heat exchanger and then returning it to the upper part of the hot water storage tank; a boiling mode determination means for setting the heating capacity of the heat pump circuit; and the boiling mode Boiling control means for controlling the heat pump circuit and the hot water storage circuit according to the heating capacity set by the judging means, defrosting judging means for detecting the start and end of the defrosting operation of the heat pump circuit, and the heat pump and a defrosting control unit of circuit, the defrosting determining means, on the basis of the evaporator temperature to determine the defrosting start conditions, than when the small when heating capacity is large, before starting the defrosting By setting a low temperature of the evaporator, even when the heating capacity of the heat pump circuit is switched to the large capacity of the small capacity can continue to boiling over operation without shifting to the defrosting operation, the heating of the heat pump circuit Insufficient capacity and running out of hot water storage tank can be prevented.

  In the second invention, in particular, the defrosting determination means of the heat pump water heater according to the first invention has an evaporator outlet temperature detected by the evaporator outlet temperature sensor when the heating operation time of the heat pump circuit is longer than a predetermined time. The defrosting start temperature is detected when the temperature is equal to or lower than the defrosting start temperature, and when the heating capacity set by the boiling mode determination means is small, the defrosting start temperature is increased and the heating capacity set by the boiling mode determination means Is large, the defrosting start temperature is set low, and it is possible to shift to the defrosting operation at an appropriate timing according to the heating capacity of the heat pump circuit. , Can save energy.

  The third aspect of the invention relates to the heat pump particularly when the amount of remaining hot water in the hot water storage tank detected by the remaining hot water amount sensor detected by the boiling mode determination means of the heat pump water heater of the first or second aspect of the invention is greater than or equal to a predetermined amount. When the amount of remaining hot water in the hot water storage tank detected by the remaining hot water amount sensor is less than a predetermined amount, the heating capacity of the heat pump circuit is set large, and the heat pump circuit has a simple configuration. It is possible to accurately control the heating capacity of the hot water storage tank and prevent the hot water storage tank from running out.

  In particular, the fourth aspect of the invention relates to the defrosting control means of the heat pump water heater of any one of the first to third aspects of the invention, wherein one end of the defrosting valve is connected to the discharge pipe of the compressor and the other end is upstream of the expansion valve. It is connected to the downstream side, and hot gas discharged from the compressor is bypassed to the evaporator through the defrost valve, and the defrosting operation is promptly terminated to shift to the boiling operation. The heat pump can be operated with high efficiency.

  In the fifth aspect of the invention, in particular, the heat pump circuit of the heat pump water heater of any one of the first to fourth aspects of the invention is a supercritical heat pump cycle in which the pressure of the refrigerant is equal to or higher than the critical pressure, and the pressure is increased to the critical pressure or higher. By heating the water in the water-side pipe of the hot water supply heat exchanger with the refrigerant, the refrigerant in the refrigerant-side pipe of the hot water supply heat exchanger is pressurized to a critical pressure or higher, so the water in the hot water supply heat exchanger Condensation does not occur even if the temperature is lowered due to the water in the side pipe. Therefore, it becomes easy to form a temperature difference between the refrigerant and the water in the entire area of the hot water heat exchanger, so that hot water can be obtained and the heat exchange efficiency can be increased.

  The sixth invention is the heat pump water heater of the fifth invention, in which the refrigerant to be used is carbon dioxide, and the product cost is reduced by using relatively inexpensive and stable carbon dioxide for the refrigerant. It is possible to reduce the reliability and improve the reliability. In addition, carbon dioxide has an ozone depletion coefficient of zero and a global warming coefficient of about 1/700 of the alternative refrigerant HFC-407C, which is very small.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a heat pump water heater according to a first embodiment of the present invention.

  In FIG. 1, a compressor 11, a refrigerant side pipe 12 a of a hot water supply heat exchanger, an expansion valve 13, and an evaporator 14 are annularly connected to form a heat pump circuit, and a discharge refrigerant temperature of the compressor 11 is detected. A discharge temperature sensor 17 and an evaporator outlet temperature sensor 18 for detecting the outlet refrigerant temperature of the evaporator 14 are installed. The heat pump circuit connects one end of the defrost valve 16 to the discharge pipe of the compressor 11 and the other end between the refrigerant side pipe 12a of the hot water supply heat exchanger and the expansion valve 13, and is discharged from the compressor 11. A defrosting circuit for bypassing the hot gas to the evaporator 14 via the defrosting valve 16 is provided. The evaporator 14 has a fan 15, and heat exchange is performed between the air supplied to the evaporator 14 by the fan 15 and the refrigerant in the evaporator 14. On the other hand, the hot water storage tank 19, the laminated pump 20, and the water side pipe 12b of the hot water heat exchanger are connected in an annular shape, and the water in the lower part of the hot water tank 19 is heated in the water side pipe 12b of the hot water heat exchanger and then the hot water storage tank. 19, a hot water storage circuit returning to the upper part is formed, and an incoming water temperature sensor 21 for detecting the inlet water temperature of the water side pipe 12b of the hot water heat exchanger, and a hot water temperature sensor for detecting the outlet water temperature of the water side pipe 12b of the hot water heat exchanger. 22. A remaining hot water amount sensor 23 for detecting the remaining hot water amount in the hot water storage tank 19 is installed. The hot water storage tank 19 is connected to a hot water supply pipe 24 for supplying water to the hot water storage tank 19 and a hot water supply pipe 25 for supplying hot water in the hot water storage tank 19 to the outside.

  Further, the heat pump water heater of the present invention includes a boiling mode determination means 26 for setting the heating capacity of the heat pump circuit during the boiling operation, and a heat pump circuit and a hot water storage circuit according to the heating capacity set by the boiling mode determination means 26. And a defrosting determining means 28 for detecting the start and end of the defrosting operation of the heat pump circuit, and a defrosting control means 29 for the heat pump circuit.

  The boiling mode determination means 26 reduces the heating capacity of the heat pump circuit when the amount of remaining hot water in the hot water storage tank 19 detected by the remaining hot water amount sensor 23 is equal to or greater than a predetermined amount, and the remaining amount in the hot water storage tank 19 detected by the remaining hot water amount sensor 23. When the amount of hot water is less than a predetermined amount, the heating capacity of the heat pump circuit is set large.

  The defrost determination means 28 detects the start of the defrost operation when the boiling operation time of the heat pump circuit is equal to or longer than a predetermined time and the evaporator outlet temperature detected by the evaporator outlet temperature sensor 18 is equal to or lower than the defrost start temperature. When the heating capacity set by the boiling mode determination unit 26 is small, the defrosting start temperature is set high. When the heating capacity set by the boiling mode determination unit 26 is large, the defrosting start temperature is set low.

  About the heat pump water heater comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  First, when the amount of remaining hot water in the hot water storage tank 19 is equal to or greater than a predetermined amount (for example, the detected temperature of the remaining hot water amount sensor 23 at the center of the hot water storage tank 19 is 45 ° C. or higher), the heating mode determination means 26 heats the heat pump circuit. The capacity is set to the rated capacity (for example, 6 kW). The boiling control means 27 controls the operating frequency of the compressor 11 and the rotation speed of the fan 15 to predetermined target values and detects them by the discharge temperature sensor 17 so that the heating capacity of the heat pump circuit becomes the rated capacity. The opening degree of the expansion valve 13 is controlled so that the discharge temperature becomes the target discharge temperature, and the flow rate of the laminated pump 20 is controlled so that the hot water temperature detected by the hot water temperature sensor 22 becomes the target hot water temperature. When the heating capacity of the heat pump circuit is set to the rated capacity, the boiling operation time of the heat pump circuit is a predetermined time or more and the evaporator outlet temperature detected by the evaporator outlet temperature sensor 18 is the first defrost start temperature ( For example, the start of the defrosting operation is detected in the case of −7 ° C. or lower, and the defrosting control unit 29 performs the defrosting operation. During the defrosting operation, the fan 15 is stopped and the defrosting valve 16 is opened, and the opening degree of the expansion valve 13 is fully opened, and the refrigerant is expanded along the broken line arrow in FIG. The valve 13 and the evaporator 14 flow in this order and return to the compressor 11. The refrigerant (hot gas) discharged from the compressor 11 bypasses the refrigerant-side pipe 12a of the hot water supply heat exchanger and flows into the evaporator 14, and melts frost adhering to the surface of the evaporator 14.

  Next, when the amount of remaining hot water in the hot water storage tank 19 is less than a predetermined amount (for example, the temperature detected by the remaining hot water amount sensor 23 in the central portion of the hot water storage tank 19 is lower than 45 ° C.), the boiling mode determination means 26 uses the heat pump circuit. The heating capacity is set to the maximum capacity (for example, 10 kW). The elevating control means 27 controls the operating frequency of the compressor 11 and the rotational speed of the fan 15 to predetermined target values and detects them by the discharge temperature sensor 17 so that the heating capacity of the heat pump circuit becomes the maximum capacity. The opening degree of the expansion valve 13 is controlled so that the discharge temperature becomes the target discharge temperature, and the flow rate of the stacking pump 20 is controlled so that the hot water temperature detected by the hot water temperature sensor 22 becomes the target hot water temperature, thereby quickly storing hot water. Refill the tank 19 with hot water. When the heating capacity of the heat pump circuit is set to the maximum capacity, the boiling operation time of the heat pump circuit is a predetermined time or more and the evaporator outlet temperature detected by the evaporator outlet temperature sensor 18 is the second defrost start temperature ( For example, in the case of −10 ° C. or less, the start of the defrosting operation is detected, and the defrosting control unit 29 performs the defrosting operation.

Consider a case where a large amount of hot water in the hot water storage tank 19 is used when the heat pump circuit is operating at the rated capacity (6 kW) in the heat pump water heater that operates as described above. When a large amount of hot water is used, the detected temperature of the remaining hot water sensor 23 eventually becomes less than 45 ° C., and it is detected that the remaining hot water amount in the hot water storage tank 19 is less than a predetermined amount. At this time, the boiling mode determination means 26 performs the operation of setting the heating capacity of the heat pump circuit to the maximum capacity (10 kW) and quickly refilling the hot water storage tank 19 with hot water. At this time, since the frequency of the compressor 11 increases, the evaporation temperature (evaporator outlet temperature) decreases. Therefore, when the defrosting start temperature is set based on the rated capacity standard of the heat pump circuit, the evaporator outlet temperature becomes equal to or lower than the defrosting start temperature, and the start of the defrosting operation is detected. That is, the defrosting operation is started by increasing the heating capacity of the heat pump circuit in order to quickly replenish hot water into the hot water storage tank 19, and it is easy for the hot water storage tank 19 to run out of hot water. is there. On the other hand, if the defrosting start temperature is set with the maximum standard of the heat pump circuit, the defrosting start timing is delayed when the heat pump circuit is operated at the rated capacity, and the efficiency of the boiling operation and the defrosting operation is reduced. Invite.

  Therefore, the defrosting start temperature (second defrosting start temperature) when the heating capacity of the heat pump circuit is large (maximum capacity) is the defrosting starting temperature (first removal) when the heating capacity of the heat pump circuit is small (rated capacity). By setting the temperature lower than the frost start temperature), the boiling operation can be continued without detecting the start of the defrost even when the heating capacity of the heat pump circuit is switched from the rated capacity to the maximum capacity. Furthermore, the boiling operation and the defrosting operation can be efficiently performed by setting an appropriate defrosting start temperature corresponding to the heating capacity of the heat pump circuit.

  As described above, in the first embodiment, even when the heating capacity of the heat pump circuit is switched from the rated capacity to the maximum capacity, the boiling operation can be continued without entering the defrosting operation, and the hot water tank 19 runs out of water. Not only can it be prevented, but also high-efficiency boiling operation and defrosting operation can be performed by a heat pump circuit, and energy saving of equipment can be achieved.

  In the above, when the heat pump circuit is operated at the maximum capacity, the heat capacity is expressed as large, and when the heat pump circuit is operated at the rated capacity, the heat capacity is expressed as small. Although described, this is only an example and does not limit the present invention. In short, when the heating capacity of the heat pump circuit is relatively increased, the defrosting start temperature is set low. Conversely, when the heating capacity of the heat pump circuit is relatively decreased, the defrosting start temperature is set high. By the way.

  Although not shown in FIG. 1, the present invention is also effective when hot water heated by a heat pump circuit is supplied directly from a currant (faucet) or a shower without returning to the hot water storage tank 19.

(Embodiment 2)
FIG. 2 is a configuration diagram of a heat pump water heater according to the second embodiment of the present invention. In FIG. 2, the same components as those of the heat pump water heater of the first embodiment of the present invention are denoted by common reference numerals, and detailed description thereof is omitted.

What is different from the first embodiment is the configuration of the defrosting circuit of the heat pump circuit. In FIG. 2, during the defrosting operation, the fan 15 is stopped and the opening of the expansion valve 13 is fully opened, and the refrigerant is along the broken line arrow in FIG. 2, the compressor 11, the refrigerant side pipe 12 a of the hot water supply heat exchanger, It flows in the order of the expansion valve 13 and the evaporator 14 and returns to the compressor 11. The refrigerant discharged from the compressor 11 (hot gas) flows into the evaporator 14 without bypassing the refrigerant side pipe 12a of the hot water supply heat exchanger, and melts frost adhering to the surface of the evaporator 14. Thus, even if the defrosting circuit of the heat pump is different, the determination of the defrosting start by the defrosting determination means 28 can be performed similarly to the heat pump water heater of the first embodiment of the present invention. For example, as another defrosting circuit configuration of the second embodiment of the present invention, reverse cycle defrosting is performed by providing a heat pump circuit with a four-way valve (not shown) that reverses the flow direction of the refrigerant. However, also in a heat pump water heater using this reverse cycle defrosting method, the present invention can obtain the same effects as the first or second invention of the present invention.

  In the first embodiment and the second embodiment, the cycle of the heat pump circuit is a supercritical heat pump cycle in which the pressure of the refrigerant is equal to or higher than the critical pressure. In this case, chlorofluorocarbon, ammonia, or the like may be used as the refrigerant.

  As described above, the heat pump water heater according to the present invention is particularly effective for efficiently performing defrosting in a variable capacity heat pump cycle.

Configuration diagram of heat pump water heater in Embodiment 1 of the present invention The block diagram of the heat pump water heater in Embodiment 2 of this invention Configuration diagram of conventional heat pump water heater

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Compressor 12 Hot-water supply heat exchanger 12a Refrigerant-side piping of hot-water supply heat exchanger 12b Water-side piping of hot-water supply heat exchanger 13 Expansion valve 14 Evaporator 15 Fan 16 Defrost valve 17 Discharge temperature sensor 18 Evaporator outlet temperature sensor 19 Hot water storage Tank 20 Laminated pump 21 Incoming water temperature sensor 22 Hot water temperature sensor 23 Remaining hot water amount sensor 24 Water supply pipe 25 Hot water supply pipe 26 Boiling mode determination means 27 Boiling control means 28 Defrosting determination means 29 Defrost control means 29

Claims (6)

A heat pump circuit having a refrigerant side piping, an expansion valve and an evaporator of a compressor, a hot water supply heat exchanger, a hot water storage tank, a stacking pump, and a water side piping of a hot water supply heat exchanger are connected to supply water below the hot water storage tank. A hot water storage circuit that is heated in the water side pipe of the hot water heat exchanger and then returned to the upper part of the hot water storage tank, a boiling mode determination unit that sets a heating capacity of the heat pump circuit, and a heating set by the boiling mode determination unit Boiling control means for controlling the heat pump circuit and the hot water storage circuit according to capacity, defrost determination means for detecting the start and end of the defrosting operation of the heat pump circuit, and defrost control means for the heat pump circuit with the door, the defrosting determining means, the defrosting start condition determined based on the evaporator temperature, than when the small when heating capacity is large, the temperature of the evaporator to start defrosting The heat pump water heater, characterized in that the set lower. The defrosting determination means detects the start of the defrosting operation when the boiling operation time of the heat pump circuit is a predetermined time or more and the evaporator outlet temperature detected by the evaporator outlet temperature sensor is equal to or lower than the defrosting start temperature, When the heating capacity set by the boiling mode determination means is small, the defrosting start temperature is set high, and when the heating capacity set by the boiling mode determination means is large, the defrosting start temperature is set low. The heat pump water heater according to claim 1. The boiling mode determination means reduces the heating capacity of the heat pump circuit when the amount of remaining hot water in the hot water tank detected by the remaining hot water sensor is greater than or equal to a predetermined amount, and the amount of hot water in the hot water tank detected by the remaining hot water sensor is a predetermined amount. The heat pump water heater according to claim 1 or 2, wherein if it is less than 1, the heating capacity of the heat pump circuit is set large. The defrosting control means connects one end of the defrosting valve to the discharge pipe of the compressor, the other end to the upstream or downstream side of the expansion valve, and sends hot gas discharged from the compressor via the defrosting valve. The heat pump water heater according to any one of claims 1 to 3, wherein the evaporator is bypassed. The heat pump circuit is a supercritical heat pump cycle in which the refrigerant pressure on the high-pressure side becomes equal to or higher than the critical pressure, and heats water in the water-side piping of the hot water supply heat exchanger with the refrigerant whose pressure is increased to the critical pressure or higher. The heat pump water heater according to any one of 4. The heat pump water heater according to claim 5, wherein the refrigerant to be used is carbon dioxide.

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