JP2017075761A - Water heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water heating device that can detect refrigerant leakage early.SOLUTION: In the water heating device, a water heat exchanger temperature sensor 43 for detecting condensation temperature and a liquid pipe temperature sensor 42 for detecting refrigerant temperature at an outlet of a water heat exchanger 22 are combined to constitute single second detection means 49 for detecting an overcooling degree. An inflow water temperature sensor 46 detects inflow water temperature of the water heat exchanger 22. A control device 50 of a heat pump unit 20 detects refrigerant leakage from a refrigerant circuit based on a calculated overcooling degree correction value where the overcooling degree is corrected by the inflow water temperature.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water heating apparatus that heats water using heat exchange between a refrigerant and water.

  Conventionally, as a water heating apparatus that heats water using a heat pump based on a vapor compression refrigeration cycle, for example, hot water in a hot water tank as described in Patent Document 1 (JP 2013-170780 A) is heated. Heat pump devices are known. In such a heat pump device, the refrigerant may leak due to breakage of the piping, a problem of brazing, or the like. Therefore, in the heat pump device described in Patent Document 1, refrigerant leakage is detected from a change in heating capability caused by a change in the amount of refrigerant in the refrigerant circuit.

  However, in the heat pump device described in Patent Document 1, since the rate of change in the heating capacity with respect to the change in the amount of refrigerant is small, there may be cases where a large amount of refrigerant has already leaked when refrigerant leakage can be detected. It is likely to occur. In such a water heating apparatus that heats water with a refrigerant using a heat pump, the initial refrigerant filling amount may be small, and if a refrigerant leak is detected by a method as described in Patent Document 1, compression is performed. There is a problem that it is difficult to detect refrigerant leakage at an early stage before the machine breaks down.

  The subject of this invention is providing the water heating apparatus which can detect a refrigerant | coolant leak at an early stage.

  A water heating apparatus according to a first aspect of the present invention includes a water heat exchanger that performs heat exchange between a refrigerant and water, and includes a refrigerant circuit that performs a vapor compression refrigeration cycle, and an incoming temperature of the water heat exchanger. A first detection means for detecting, and a second detection means for detecting the degree of supercooling of the refrigerant that has exited the water heat exchanger, the degree of supercooling detected using the second detection means, The refrigerant leakage of the refrigerant circuit is detected based on the calculated supercooling degree correction value corrected with the incoming water temperature detected using the first detection means.

  In this water heating apparatus, the refrigerant leakage of the refrigerant circuit is detected based on the calculated supercooling degree correction value obtained by correcting the supercooling degree detected using the second detecting means with the incoming water temperature detected by the first detecting means. From this, it is possible to detect with a calculated supercooling degree correction value that changes sharply with respect to refrigerant leakage.

  A water heating apparatus according to a second aspect of the present invention is the water heating apparatus according to the first aspect, further comprising third detection means for detecting the condensation temperature of the water heat exchanger, and using the third detection means. A value obtained by dividing the degree of supercooling detected using the second detecting means by the difference between the detected condensing temperature and the incoming water temperature detected using the first detecting means is used as the calculated supercooling degree correction value. Detects refrigerant leakage in the refrigerant circuit.

  In this water heating device, the value obtained by dividing the degree of supercooling by the difference between the condensing temperature and the incoming water temperature is used as the calculated supercooling degree correction value, so fluctuations in the calculated supercooling degree correction value accompanying fluctuations in the incoming water temperature are suppressed. Is done.

  The water heating device according to a third aspect of the present invention is the water heating device according to the second aspect, wherein the calculated supercooling degree correction value is compared with a specific supercooling degree correction value when the refrigerant in the refrigerant circuit has a specific refrigerant amount. Thus, the occurrence of refrigerant leakage in the refrigerant circuit is determined.

  In this water heating device, the occurrence of refrigerant leakage is determined by comparing the calculated supercooling degree correction value of the refrigerant circuit with the specific supercooling degree correction value. Differences in the cooling degree correction value can be compared, and errors occurring in the calculated supercooling degree correction value depending on, for example, the model and pipe length of the water heating device can be suppressed.

  The water heating device according to the fourth aspect of the present invention is the water heating device according to the third aspect, wherein the water heating device according to the third aspect is calculated to be less than a predetermined ratio of the specific supercooling degree correction value when the specific refrigerant amount is the refrigerant amount at the initial filling. When the cooling degree correction value decreases, it is determined that refrigerant leakage has occurred in the refrigerant circuit.

  In this water heating device, it is determined that refrigerant leakage has occurred when the calculated supercooling degree correction value is equal to or less than a predetermined ratio of the specific supercooling degree correction value, so the specific supercooling degree correction value is measured during initial filling. Therefore, preparation for comparison between the calculated supercooling degree correction value and the specific supercooling degree correction value is simplified, and the determination of refrigerant leakage can be quickly made only by comparing the values.

  A water heating apparatus according to a fifth aspect of the present invention is the water heating apparatus according to the first aspect to the fourth aspect, further comprising fourth detection means for detecting a tapping temperature of the water heat exchanger, The refrigerant leakage of the refrigerant circuit is detected when the difference obtained by subtracting the incoming water temperature detected using the first detecting means from the temperature of the hot water detected using the means is equal to or greater than a predetermined value. , That is.

  In this water heating apparatus, the difference obtained by subtracting the incoming water temperature detected using the first detection means from the tapping temperature detected using the fourth detection means is equal to or greater than a predetermined value. After confirming that the refrigerant circuit is performing a stable vapor compression refrigeration cycle, refrigerant leakage detection can be performed.

  In the water heating apparatus according to the first aspect of the present invention, refrigerant leakage can be detected at an early stage based on the calculated supercooling degree correction value.

  In the water heating apparatus according to the second aspect of the present invention, the accuracy of refrigerant leakage detection can be improved.

  In the water heating apparatus according to the third aspect of the present invention, it is possible to easily perform refrigerant leakage detection with a small error and high accuracy.

  In the water heating apparatus according to the fourth aspect of the present invention, refrigerant leakage detection can be performed easily and quickly.

  In the water heating apparatus according to the fifth aspect of the present invention, the refrigerant leakage of the refrigerant circuit can be accurately detected in a stable state of the refrigerant circuit.

The circuit diagram of the hot-water supply apparatus containing the heat pump unit which concerns on one Embodiment of this invention. The block diagram which shows the outline of the control system of the heat pump unit of FIG. The figure for demonstrating the relationship between the driving | running state of a heat pump unit, and a refrigerant | coolant amount. The graph which shows an example of the relationship between the refrigerant | coolant amount in a heat pump unit, and the calculated supercooling degree correction value. The flowchart which shows an example of the flow of a refrigerant | coolant leak detection.

(1) Outline of hot water supply apparatus including water heating apparatus An outline of a configuration of a hot water supply apparatus including a water heating apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a heat pump unit 20 as an example of a water heating device. The heat pump unit 20 constitutes the hot water supply device 10 together with the hot water storage unit 60. The heat pump unit 20 has a function of heating water to obtain hot water stored in the hot water storage unit 60. For example, the hot water storage unit 60 stores hot water heated by the heat pump unit 20 in order to supply the hot water to the bathtub 80 and other hot water supply terminals.

  The hot water storage unit 60 includes a hot water storage tank 61 having a heat retaining function, a reheating heat exchanger 62 for reheating hot water (or water) stretched on the bathtub 80, a first circulation pump 63, and a second circulation pump. 64.

  The first circulation pump 63 is connected to a bathtub circulation pipe 65. The bathtub circulation pipe 65 forms a bathtub circulation path from which hot water returns from the bathtub 80 to the bathtub 80 via the first circulation pump 63 and the reheating heat exchanger 62. The second circulation pump 64 is connected to a recirculation circulation pipe 66. The recirculation piping 66 forms a bathtub circulation path in which hot water returns from the hot water storage tank 61 to the hot water storage tank 61 via the reheating heat exchanger 62 and the second circulation pump 64.

  The hot water supply terminal to which hot water is supplied from the hot water storage unit 60 is not limited to the bathtub 80. For example, a hot water supply pipe 67 may be connected to the top of the hot water storage tank 61 to supply hot water to hot water supply terminals other than the bathtub 80. Examples of hot water supply terminals other than the bathtub 80 include a bathroom faucet, a kitchen faucet, and a bathroom shower.

  A water supply pipe 68 is connected to the bottom of the hot water tank 61. The water supply pipe 68 is connected to an external water supply source 90. For example, tap water is supplied through the water supply pipe 68. Tap water is under pressure, and water is supplied from the water supply source 90 to the hot water storage tank 61 with the pressure.

  An outlet pipe 71 is provided at the bottom of the hot water tank 61, and an inlet pipe 72 is provided at the top of the hot water tank 61. The outlet pipe 71 and the inlet pipe 72 are connected to the inlet pipe 33 and the outlet pipe 34 of the heat pump unit 20, respectively.

  For example, once a day, cold water supplied from the water supply source 90 to the bottom of the hot water tank 61 is heated by the water heat exchanger 22, and hot water is added from the top of the hot water tank 61 and stored.

(2) Configuration of Heat Pump Unit 20 The heat pump unit 20 includes a compressor 21, a water heat exchanger 22, a filter-equipped muffler 23, an expansion mechanism 24, a filter-equipped branch muffler 25, and air heat exchange that are sequentially arranged. And a refrigerant circuit 30 including an accumulator 27. The refrigerant circuit 30 performs a vapor compression refrigeration cycle by circulating refrigerant in the circuit. The refrigerant flowing through the refrigerant circuit 30 is, for example, R32 refrigerant. The heat pump unit 20 includes a fan 31 that generates an airflow passing through the air heat exchanger 26 in order to promote heat exchange in the air heat exchanger 26. The fan 31 is a fan capable of changing the air volume of air supplied to the air heat exchanger 26, and is, for example, a centrifugal fan or a multiblade fan driven by a motor such as a DC fan motor. Further, the compressor 21 is a compressor capable of changing the operation capacity, and is a positive displacement compressor whose rotation speed is controlled by an inverter.

  In the heat pump unit 20, an inlet pipe 33 and an outlet pipe 34 are connected to the water heat exchanger 22. A third circulation pump 32 is connected to the inlet pipe 33. The inlet pipe 33 of the heat pump unit 20 and the outlet pipe 71 of the hot water storage unit 60 are connected, and the outlet pipe 34 of the heat pump unit 20 and the inlet pipe 72 of the hot water storage unit 60 are connected, so that the hot water storage tank 61 and the third circulation pump 32 are connected. And a hot water heating circuit in which warm water is circulated through the water heat exchanger 22 to heat the warm water.

  For the control of the heat pump unit 20, the discharge pipe temperature sensor 41, the liquid pipe temperature sensor 42, the water heat exchanger temperature sensor 43, the air heat exchanger temperature sensor 44, the outside air temperature sensor 45, and the incoming water temperature sensor. 46, a tapping temperature sensor 47, and a pressure sensor 48 are connected to the control device 50. The discharge pipe temperature sensor 41 is attached to the discharge pipe of the compressor 21 and detects the temperature of the refrigerant discharged from the compressor 21. The liquid pipe temperature sensor 42 is provided at the refrigerant outlet of the water heat exchanger 22 and detects the temperature of the refrigerant flowing out of the water heat exchanger 22. The water heat exchanger temperature sensor 43 is provided between the refrigerant inlet and the refrigerant outlet of the water heat exchanger 22 and detects the temperature of the refrigerant flowing in the water heat exchanger 22. The heat pump unit 20 uses the temperature detected by the water heat exchanger temperature sensor 43 as the condensation temperature Tc. The subcooling degree SC (= Tc−To) is calculated by subtracting the refrigerant temperature To detected by the liquid pipe temperature sensor 42 from the condensation temperature Tc. The degree of supercooling is about 30 ° C., for example. The air heat exchanger temperature sensor 44 is provided between the refrigerant inlet and the refrigerant outlet of the air heat exchanger 26 and detects the temperature of the refrigerant flowing through the air heat exchanger 26. The outside air temperature sensor 45 detects the temperature of outside air that is taken into the heat pump unit 20 by the fan 31 and passes through the air heat exchanger 26. The pressure sensor 48 detects the pressure of the discharge pipe of the compressor 21. For example, when the pressure of the discharge pipe of the compressor 21 exceeds a threshold value and becomes dangerous, the heat pump unit 20 can stop the operation based on the detection result of the pressure sensor 48.

  The incoming water temperature sensor 46 is provided in the inlet pipe 33 and detects the water temperature of water (or hot water) flowing into the water heat exchanger 22. The hot water temperature sensor 47 is provided in the outlet pipe 34 and detects the temperature of hot water flowing out from the water heat exchanger 22.

  As shown in FIG. 2, the control device 50 controls the compressor 21, the expansion mechanism 24, the fan 31, and the third circulation pump 32. The control device 50 is configured using a microcomputer having a CPU, a memory, and the like.

(3) Operation of the heat pump unit 20 When supplying hot water to the hot water storage tank 61, when the third circulation pump 32 is driven by the control device 50, tap water supplied from the water supply source 90 to the bottom of the hot water storage tank 61 is supplied. The water heat exchanger 22 is entered through the outlet pipe 71 of the hot water storage unit 60 and the inlet pipe 33 of the heat pump unit 20.
The temperature of the water flowing into the water heat exchanger 22 is detected by the incoming water temperature sensor 46 and transmitted to the control device 50. In the water heat exchanger 22, the inflowing water is heated by heat exchange with the refrigerant to become warm water, and the warm water flows out through the outlet pipe 34. At this time, the temperature of the refrigerant flowing through the water heat exchanger 22 is detected by the water heat exchanger temperature sensor 43. Further, the temperature of hot water flowing through the outlet pipe 34 is detected by a hot water temperature sensor 47.

  The target hot water temperature is determined by the control device 50 based on data stored in the memory 52. The hot water heated to the target hot water temperature by the water heat exchanger 22 is poured from the top of the hot water storage tank 61 through the outlet pipe 34 and the inlet pipe 72 of the hot water storage unit 60.

  In the refrigerant circuit 30, the refrigerant is compressed by the compressor 21, and the high-temperature gas refrigerant is discharged from the discharge pipe of the compressor 21. The target discharge pipe temperature, which is the target temperature of the gas refrigerant discharged from the compressor 21, is determined from the target hot water temperature. For example, the target discharge pipe temperature suitable for obtaining the target hot water temperature determined by the control device 50 is determined by the control device 50 reading data stored in the memory 52 in advance, or stored in the memory 52. It is determined by the controller 50 using the data.

  In addition, the outside air temperature detected by the outside air temperature sensor 45 is transmitted to the control device 50, and the control device 50 determines the operating frequency of the compressor 21 from the target discharge pipe temperature and the outside air temperature. Usually, since the outside air temperature hardly changes during one hot water supply of the heat pump unit 20, the operation frequency during one hot water supply is also fixed. If the target discharge pipe temperature and the operating frequency of the compressor 21 are fixed, the supercooling degree SC is also fixed if there is no refrigerant leakage.

  The high-temperature and high-pressure gas refrigerant discharged from the compressor 21 is condensed in the water heat exchanger 22, and the refrigerant liquefied by heat exchange with water passes through the filter-equipped muffler 23 to the expansion mechanism 24. Sent. At this time, the temperature of the refrigerant at the outlet of the water heat exchanger 22 is detected by the liquid pipe temperature sensor 42. Then, the gas-liquid two-phase refrigerant whose temperature is reduced by expansion by the expansion mechanism 24 is branched by the filter-equipped branch muffler 25 and flows into the air heat exchanger 26. In the air heat exchanger 26, the refrigerant gasified by heat exchange with the outside air sucked into the heat pump unit 20 by the fan 31 is sucked into the compressor 21 through the accumulator 27. At this time, the temperature (evaporation temperature) of the refrigerant flowing through the air heat exchanger 26 is detected by the air heat exchanger temperature sensor 44. The control device 50 adjusts the opening degree of the expansion mechanism 24 while detecting the evaporation temperature and the outside air temperature, adjusts the air volume of the fan 31, and performs control so that overheating occurs at the suction port of the compressor 21.

(4) Refrigerant Leakage Detection In the hot water supply operation in which hot water is accumulated using the heat pump unit 20 as described above, the target discharge pipe temperature is determined from the target hot water supply temperature of the hot water sent to the hot water storage tank 61. Further, the operating frequency of the compressor 21 is determined from the outside air temperature. Thus, since the target discharge pipe temperature and the operating frequency of the compressor 21 are fixed, it changes sensitively according to the amount of refrigerant filled with the degree of supercooling SC (= Tc-To).

  FIG. 3 illustrates the relationship between the operation state of the heat pump unit 20 and the refrigerant amount. FIG. 4 shows an example of the relationship between the refrigerant amount and the calculated supercooling degree correction value. 3 and 4 show data relating to the heat pump unit 20 in a period called the middle period of spring and autumn. In summer during the intermediate period, the incoming water temperature is higher than in the intermediate period, and in winter during the intermediate period, the incoming water temperature is lower than in the intermediate period. Since water having substantially the same temperature as the tap water is supplied from the bottom of the hot water tank 61, the incoming water temperature is approximately proportional to the outside air temperature in this case. For example, when the outside air temperature is 16 ° C., it can be estimated that the incoming water temperature is 17 ° C., when the outside air temperature is 7 ° C., it can be estimated that the incoming water temperature is 9 ° C., and when the outside air temperature is 25 ° C. Can be estimated to be 24 ° C.

  An appropriate filling amount (refrigerant amount rate 100%) of the refrigerant circuit 30 is 460 g. For example, the service port 35 (see FIG. 1) is used locally to fill the refrigerant so that the amount of the refrigerant becomes this amount. The calculated supercooling degree correction value SCc used in FIGS. 3 and 4 is a value obtained by correcting the supercooling degree SC with the incoming water temperature Twi. Here, the calculated supercooling degree correction value SCc is calculated by dividing the supercooling degree SC by a value obtained by subtracting the incoming water temperature Twi from the condensation temperature Tc. That is, in the heat pump unit 20, the calculated supercooling degree correction value SCc is defined by the equation (1).

  SCc = SC ÷ (Tc−Twi) (1)

  Referring to FIG. 4, for example, when the refrigerant rate is reduced by 10% from 100% to 90%, the calculated supercooling degree correction value SCc is reduced by about half. From this, it can be seen that since the calculated supercooling degree correction value SCc changes greatly even with a small change in the refrigerant amount rate, early detection of refrigerant leakage is easy.

  In particular, the amount of refrigerant charged in the heat pump unit 20 is smaller than that of, for example, an air conditioner that configures a refrigerant circuit with an indoor unit and an outdoor unit and performs a vapor compression refrigeration cycle. The compressor 21 is easily damaged. Therefore, by utilizing the fact that the calculated supercooling degree correction value SCc changes greatly even with a small change in the refrigerant amount rate, the control device 50 detects refrigerant leakage before the compressor 21 is damaged. The operation of the heat pump unit 20 can be stopped, or the leakage of the refrigerant can be notified by displaying it on the display screen of the remote controller 51.

  Next, a refrigerant leakage detection flow will be described with reference to FIG. First, in the first step S1, the control device 50 receives the incoming water temperature Twi and the outgoing hot water temperature Two of the water heat exchanger 22 from the incoming water temperature sensor 46 and the outgoing hot water temperature sensor 47. And the control apparatus 50 reads the predetermined value previously memorize | stored in the memory 52, and compares the difference of the incoming water temperature Twi and the tapping temperature Two with a predetermined value (step S2). If the incoming water temperature Twi and the outgoing hot water temperature Two are equal to or higher than a predetermined value, the process proceeds to the next step S3 in order to detect leakage. However, if the incoming water temperature Twi and the outgoing hot water temperature Two are less than the predetermined values, the process is terminated without detecting refrigerant leakage. For example, the leak detection may be stopped when the outdoor temperature becomes too high in summer and the incoming water temperature Twi and the outgoing hot water temperature Two become smaller than predetermined values. If the difference between the incoming water temperature Twi and the outgoing hot water temperature Two is small, the refrigerant circuit 30 will not be stable, so the flow rate of refrigerant will not be known, and the compressor 21 will be unstable and the refrigerant leakage will be difficult to detect. The heat pump unit 20 performs control so as not to detect refrigerant leakage in such a situation. Thus, when the refrigerant leak detection is stopped, information indicating that the refrigerant leak detection is stopped may be notified using, for example, the remote controller 51.

  In step S <b> 3, the control device 50 receives the condensation temperature Tc from the water heat exchanger temperature sensor 43. Further, in step S <b> 4, the control device 50 receives the refrigerant temperature To at the outlet of the water heat exchanger 22 from the liquid pipe temperature sensor 42. Then, the control device 50 calculates the degree of supercooling SC by subtracting the refrigerant temperature To from the condensation temperature Tc (step S5).

  Next, using the supercooling degree SC, the condensation temperature Tc, and the incoming water temperature Twi calculated in step S5, the control device 50 calculates the above-described equation (1) to obtain a calculated supercooling degree correction value SCc. (Step S6). On the other hand, the control device 50 reads the specific supercooling degree correction value SCs from the memory 52 (step S7). The specific supercooling degree correction value SCs is, for example, a value obtained by multiplying the supercooling degree correction value when the refrigerant amount at the initial charging is 460 g (refrigerant amount rate 100%) by a predetermined ratio. The specific supercooling degree correction value SCs is a predetermined ratio to a value obtained in advance by experiment or simulation, for example, what value the supercooling degree correction value is in the heat pump unit 20 when the refrigerant amount is 460 g. For example, it is calculated by multiplying by 0.5. The control device 50 compares the specific supercooling degree correction value SCs read from the memory 52 with a value of, for example, 0.47 (≈0.47 × 0.7) with the calculated supercooling degree correction value SCc (step S8). ). If the calculated supercooling degree correction value SCc is larger than 0.47 (SCc> 0.47), it is determined that “there is no refrigerant leakage”, and the process proceeds to step S9 to notify that there is no refrigerant leakage. If the correction value SCc is 0.47 or less (SCc ≦ 0.47), it is determined that “there is a refrigerant leak”, and the process proceeds to step S10 to notify that there is a refrigerant leak.

(5) Modification (5-1) Modification A
In the above embodiment, the case where the refrigerant leakage detection is stopped when the difference between the incoming water temperature Twi and the outgoing hot water temperature Two is not equal to or greater than a predetermined value has been described. The refrigerant leakage detection can be performed after waiting.

(5-2) Modification B
In the above embodiment, the degree of supercooling SC is detected using the water heat exchanger temperature sensor 43 and the liquid pipe temperature sensor 42, but the degree of supercooling SC may be detected by other methods. For example, the saturation temperature is obtained from the pressure of the refrigerant flowing inside the water heat exchanger 22 detected using the pressure sensor, and the supercooling degree SC is calculated from the difference between the saturation temperature and the refrigerant temperature To at the outlet of the water heat exchanger 22. May be calculated.

(5-3) Modification C
In the above embodiment, the calculated supercooling degree correction value SCc is calculated using the above-described equation (1), but the calculated supercooling degree correction value SCc is not limited to the calculation result obtained by the equation (1). . For example, a table specifying the relationship among the incoming water temperature Twi, the supercooling degree SC, and the calculated supercooling degree correction value SCc is stored in the memory 52, and the control device 50 uses the table to calculate the calculated supercooling degree correction value SCc. May be calculated.

(5-4) Modification D
Although the case where hot water is supplied from the heat pump unit 20 to the hot water storage unit 60 has been described in the above embodiment, the target for supplying hot water from the heat pump unit 20 is not limited to the hot water storage unit 60. For example, the present invention can also be applied to a heat pump unit that supplies hot water to a heating circuit such as floor heating and a radiator. When applied to a heating circuit, it is preferable to detect refrigerant leakage when heating is started and the operating frequency of the compressor 21 reaches a target value and the difference between the tapping temperature Two and the incoming water temperature Twi is large. The present invention can also be applied to a heat pump unit that supplies hot water to both the hot water storage unit and the heating circuit.

(5-5) Modification E
In the above embodiment, the specific supercooling degree correction value SCs is obtained by multiplying the refrigerant amount at the time of initial charging by a predetermined ratio, but the method for determining the specific supercooling degree correction value SCs is not limited to such a method. As the specific supercooling degree correction value SCs, a supercooling degree correction value when the refrigerant amount is a predetermined amount, for example, 360 g (refrigerant amount rate 78%) may be used. The specific supercooling degree correction value SCs is obtained in advance by experiment or simulation, for example, what value the supercooling degree correction value becomes in the heat pump unit 20 when the refrigerant amount is 360 g. The control device 50 compares the specific supercooling degree correction value SCs having a value of 0.13 read from the memory 52 with the calculated supercooling degree correction value SCc.

(5-6) Modification F
In the above-described embodiment, the case of comparison with the specific supercooling degree correction value SCs has been described. However, the method of determining refrigerant leakage is not limited to the method of comparing with the specific supercooling degree correction value SCs. For example, the calculated supercooling degree correction value SCc is stored for each predetermined period, the average value of a certain period of the calculated supercooling degree correction value SCc is compared with the average value of another constant period, and the difference is a threshold value. It may be determined that the refrigerant is leaking when the value exceeds.

(6) Features (6-1)
As described above, the heat pump unit 20 which is an example of the water heating device detects the refrigerant leakage of the refrigerant circuit 30 based on the calculated supercooling degree correction value SCc obtained by correcting the supercooling degree SC with the incoming water temperature Twi. In the heat pump unit 20, the degree of supercooling SC is calculated by subtracting the refrigerant temperature To at the outlet of the water heat exchanger 22 from the condensation temperature Tc. Accordingly, the water heat exchanger temperature sensor 43 for detecting the condensation temperature Tc and the liquid pipe temperature sensor 42 for detecting the refrigerant temperature To at the outlet of the water heat exchanger 22 are combined to form one second detection means 49 (FIG. 1). Moreover, in the heat pump unit 20, the incoming water temperature sensor 46 is a 1st detection means.

  Since the control device 50 detects the refrigerant leakage of the refrigerant circuit 30 based on the calculated supercooling degree correction value SCc, as described with reference to FIG. 4, the calculated supercooling degree correction that changes sharply with respect to the refrigerant leakage. The value SCc can be detected, and the refrigerant leakage can be detected at an early stage by the calculated supercooling degree correction value SCc. For example, in the conventional refrigerant leak detection, it is difficult to detect even if the refrigerant amount is reduced by 50%, and it may be difficult to detect until a malfunction occurs in the compressor 21, but the above-described diagram of the heat pump unit 20 In the examples shown in FIGS. 3 and 4, even when the decrease in the refrigerant amount is less than 10%, the calculated supercooling degree correction value SCc is greatly changed, and the refrigerant leakage can be easily detected.

(6-2)
The water heat exchanger temperature sensor 43 alone is third detection means for detecting the condensation temperature Tc of the water heat exchanger 22. The control device 50 uses the value obtained by dividing the supercooling degree Sc by the difference between the condensing temperature Tc and the incoming water temperature Twi shown in the above equation (1) as the calculated supercooling degree correction value SCc. A refrigerant leak is detected. As a result, fluctuations in the calculated supercooling degree correction value SCc accompanying fluctuations in the incoming water temperature Twi are suppressed, and the accuracy of refrigerant leakage detection can be improved.

(6-3)
In this heat pump unit 20, since the occurrence of refrigerant leakage is determined by comparing the calculated supercooling degree correction value SCc of the refrigerant circuit 30 with the specific supercooling degree correction value SCs, the amount of refrigerant in the heat pump unit 20 having the same configuration is determined. The difference in the supercooling degree correction value due to the difference can be compared. Therefore, an error occurring in the calculated supercooling degree correction value SCc depending on, for example, the model and the pipe length of the heat pump unit 20 can be suppressed, and the refrigerant leakage detection with a small error and high accuracy can be easily performed.

(6-4)
In this heat pump unit 20, when the calculated supercooling degree correction value SCc falls below a predetermined ratio of the specific supercooling degree correction value SCs when the specific refrigerant amount is the refrigerant amount at the time of initial filling, the refrigerant circuit 30 makes the refrigerant It is determined that a leak has occurred (step S8). Since it is only necessary to measure the specific supercooling degree correction value SCs at the time of initial filling, preparation for comparing the specific supercooling degree correction value SCs with the calculated supercooling degree correction value SCc is simplified, and refrigerant leakage is reduced. Since the judgment only compares the values, refrigerant leakage detection can be performed easily and quickly.

(6-5)
The tapping temperature sensor 47 provided in the heat pump unit 20 is fourth detecting means for detecting the tapping temperature Two of the water heat exchanger 22. When the difference (Two−Twi) obtained by subtracting the incoming water temperature Twi from the tapping temperature Two is equal to or greater than a predetermined value, the control device 50 detects refrigerant leakage in the refrigerant circuit 30 (step S2). . Therefore, in this heat pump unit 20, after confirming that the refrigerant circuit 30 is performing a stable vapor compression refrigeration cycle, refrigerant leakage detection can be performed, and the refrigerant circuit 30 can be accurately detected in a stable state. Refrigerant leakage detection can be performed.

10 Hot water supply device 20 Heat pump unit (example of water heating device)
22 Water Heat Exchanger 30 Refrigerant Circuit 43 Water Heat Exchanger Temperature Sensor (Example of Third Detection Unit)
44 Air Heat Exchanger Temperature Sensor 46 Incoming Water Temperature Sensor (Example of First Detection Means)
47 Hot water temperature sensor (example of fourth detection means)
49 Second detection means

JP 2013-170780 A

Claims (5)

A refrigerant circuit (30) including a water heat exchanger (22) for exchanging heat between the refrigerant and water, and performing a vapor compression refrigeration cycle;
First detection means (46) for detecting the incoming water temperature of the water heat exchanger;
Second detection means (49) for detecting the degree of supercooling of the refrigerant that has exited the water heat exchanger,
The refrigerant leakage of the refrigerant circuit is detected based on the calculated supercooling degree correction value obtained by correcting the supercooling degree detected using the second detecting means with the incoming water temperature detected using the first detecting means. , Water heating device. Further comprising third detection means (43) for detecting the condensation temperature of the water heat exchanger;
The degree of supercooling detected using the second detecting means is divided by the difference between the condensation temperature detected using the third detecting means and the incoming water temperature detected using the first detecting means. The refrigerant leakage of the refrigerant circuit is detected by using the calculated value as the calculated supercooling degree correction value.
The water heating apparatus according to claim 1. The occurrence of refrigerant leakage in the refrigerant circuit is determined by comparing the calculated supercooling degree correction value with a specific supercooling degree correction value when the refrigerant in the refrigerant circuit has a specific refrigerant amount.
The water heating apparatus according to claim 2. When the calculated supercooling degree correction value falls below a predetermined ratio of the specific supercooling degree correction value when the specific refrigerant amount is the refrigerant amount at the time of initial filling, refrigerant leakage has occurred in the refrigerant circuit. to decide,
The water heating apparatus according to claim 3. Further comprising a fourth detection means (47) for detecting the tapping temperature of the water heat exchanger;
When the difference obtained by subtracting the incoming water temperature detected using the first detection means from the tapping temperature detected using the fourth detection means is equal to or greater than a predetermined value, the refrigerant circuit Detect refrigerant leaks,
The water heating apparatus according to any one of claims 1 to 4.

Images