JP4295241B2 - Water heater - Google Patents

Description

The present invention relates to a hot water supply apparatus. More specifically, the present invention relates to a hot water supply apparatus that stores water heated by a heat pump in a hot water storage tank, supplies hot water stored in the hot water storage tank, and heats the hot water by a burner when necessary.
Hot water is usually stored in the hot water tank, but cold water is stored when the hot water is used up. Here, it is said that the hot water is commonly stored without distinguishing between the two. Further, the hot water and the cold water are collectively referred to as “water” without being distinguished. “Water” is not “water” in a sense opposite to “hot water”, and may be hot water or cold water.

The heat pump uses the heat energy of the outside air to heat the water, so the running cost required to heat the water can be reduced. It has a disadvantage that requires a place to install a hot water tank. It is also a problem that the hot water stored in the hot water is cooled, which requires a hot water storage tank with excellent heat retention capacity and has a disadvantage that the cost of introducing the equipment becomes high.
A hot water supply device that uses a combustion burner such as a gas burner or a kerosene burner has the disadvantage that the running cost required to heat water is high, but does not require a hot water tank because it can be heated in a short time. The installation area of the hot water supply device is small, and the introduction cost of the equipment is low.

  Then, the hybrid type hot water supply apparatus which utilizes both advantages by using both in combination is proposed, and is disclosed in Patent Document 1. The technology of Patent Document 1 includes a heat pump, a hot water storage tank, a pump that circulates water between the hot water storage tank and the heat pump, and a burner that heats water supplied from the hot water storage tank to supply hot water when necessary.

JP 2001-41574 A

In a hybrid water heater that uses a combination of a heat pump and a burner, hot water stored in the hot water tank can be used to supply hot water even after the hot water has been used up, so even if the amount of heat stored in the hot water tank is small Good. The case where a small hot water tank is enough and the installation area of a hot water tank cannot be ensured can be reduced significantly.
In the hybrid hot water supply apparatus, when the hot water temperature stored in the hot water tank is less than the required temperature, it can be heated using a burner, so the temperature of the hot water stored in the hot water tank may be low. The fact that the amount of heat stored in the hot water tank may be small is also useful for lowering the temperature of the hot water stored in the hot water tank. The necessary amount of heat storage must be ensured by storing hot water in the water). In the hybrid hot water supply apparatus, the hot water temperature stored in the hot water storage tank may be low, so that the heat storage capacity of the hot water storage tank is low. Above all, when comparing the efficiency of heat pumps heated to high temperature hot water and the efficiency of heat pumps heated to low temperature hot water, the former is significantly lower than the latter, and the hybrid type that heats and stores hot water at low temperature hot water with the heat pump In the hot water supply apparatus, the heat pump can be utilized with high efficiency. Furthermore, when a burner is not used, it is necessary to heat to a high temperature of about 90 ° C. with a heat pump, so the heat medium of the heat pump is limited. In practice, there is no other way than using carbon dioxide. When carbon dioxide is used, the efficiency is low because phase change cannot be used and latent heat cannot be used. On the other hand, in the hybrid hot water supply apparatus, it is sufficient to heat to a low temperature of about 45 ° C. Therefore, alternative chlorofluorocarbon or the like can be used as a heat medium and can be heated with high efficiency using latent heat.

  In order to utilize the advantages of the hybrid hot water supply apparatus, it is necessary to store hot water having a relatively low temperature in a small hot water tank, and there is a problem that the hot water stored is likely to be insufficient. The problem is solved by using a burner. Another problem is that if you only store hot water at a relatively low temperature in a small hot water tank, you will not be able to take full advantage of the high-efficiency heating by the heat pump, and eventually use only a burner. There is concern that it may not be very different from the efficiency of However, what actually needs hot water is, for example, a washing surface, dishwashing, a shower, and hot water of 45 ° C. or less is often sufficient. Moreover, it is rare that 50 liters or more are required continuously, and the amount of hot water supplied at one time is often 50 liters or less if the hot water filling to the bathtub is excluded. Therefore, it is possible to meet many hot water supply requirements simply by storing hot water of relatively low temperature in a small hot water tank. By simply storing hot water of relatively low temperature in a small hot water tank, it is possible to fully enjoy the advantage of heating with high efficiency by a heat pump. The hybrid hot water supply apparatus is easy to install and can reduce the running cost for hot water supply.

In order to create a state in which hot water of a predetermined temperature is stored in a small hot water tank, the hybrid hot water device disclosed in Patent Document 1 is configured to reduce the water fed from the lower part of the hot water tank to a predetermined temperature with a heat pump. The hot water heated to a predetermined temperature is returned to the upper part of the hot water tank. In this case, hot water at a predetermined temperature is stored in the upper part of the hot water storage tank, cold water is stored in the lower part of the hot water storage tank, and hot water storage proceeds in a state where the two are not mixed (hereinafter referred to as a temperature stratified state). As the amount of stored hot water increases, the boundary between the hot water and the cold water moves downward, and the hot water is stored maximum when it moves to the lowest end of the hot water tank. The hybrid water heater disclosed in Patent Document 1 heats water fed from the lower part of the hot water tank to a predetermined temperature with a heat pump, and the temperature of the water stored in the lower part of the hot water tank reaches a predetermined temperature. Stop the heat pump operation when it rises.
If the hot water in the hot water tank is in a temperature stratified state, hot water at a predetermined temperature can be supplied even when the amount of hot water is reduced, and the occurrence of a situation requiring burner heating can be suppressed.

Since the heat pump uses the heat energy of the outside air to heat water, it can obtain a COP of 1.0 or more (water heating energy / compressor energy consumption), and has high energy efficiency. However, the COP is not high in all cases, and has a characteristic that changes sensitively depending on the temperature of water heated by a heat pump. While COP is high when water is heated to low temperature hot water, COP when water is heated to high temperature hot water is sensitively reduced.
Since the hybrid hot water supply apparatus of Patent Document 1 is heated to a low temperature hot water of about 45 ° C. with a heat pump, a high COP can be obtained as compared with the case of heating to a high temperature hot water of about 80 ° C. Still, since tap water is heated to about 45 ° C while tap water passes through the heat exchanger, for example, when 15 ° C tap water is heated to 20 ° C, or 20 ° C water is heated to 25 ° C. Compared with the case, COP is low. The COP when heating 15 ° C. water to 45 ° C. with a heat pump is clearer than the COP when heating 15 ° C. water to 20 ° C. and the COP when heating 20 ° C. water to 25 ° C. Low.
The present invention was created to further increase the COP during hot water storage in a hot water storage tank using a heat pump, and improves the thermal efficiency of the hybrid hot water supply apparatus.

The hot water supply apparatus of the present invention uses a heat medium that is “a first heat exchanger that exchanges heat between the heat medium and outside air, a compressor that compresses the heat medium, and a second heat that exchanges heat between the heat medium and water. A heat pump is used that circulates through a passage that goes through a exchanger and a pressure reducing valve that releases the pressure of the heat medium. A hot water supply apparatus of the present invention includes a heat pump, a hot water storage tank, a water circulation pump that supplies water from the lower part of the hot water storage tank to the second heat exchanger and returns water heated by the second heat exchanger to the upper part of the hot water storage tank, and hot water storage It is equipped with a burner that heats the water delivered from the upper part of the tank when necessary.
The hot water supply device disclosed in the present specification is characterized by having a controller that circulates all the water in the hot water storage tank through the second heat exchanger a plurality of times and gradually raises the temperature to a target temperature. This controller maintains the heat exchange amount in the second heat exchanger at a constant level by increasing the compression ratio of the compressor every time all the water in the hot water tank passes through the second heat exchanger. Thus, the temperature of the water is raised by the same temperature in each of a plurality of times. For example, when a phenomenon occurs in which 15 ° C. water is heated to 20 ° C. and returned to the hot water tank, and the hot water tank is filled with water heated to 20 ° C., then the 20 ° C. water is heated to 25 ° C. The phenomenon to return to occurs. In this case, a particularly high COP is obtained in the initial stage of heating. As in the technique of Patent Document 1, for example, a significantly higher COP can be obtained as compared with the case where tap water at 15 ° C. is heated to 45 ° C. Even in this method, it is necessary to finally heat the water at 40 ° C. to 45 ° C., and at that stage, only a COP comparable to the COP obtained by the technique of Patent Document 1 can be obtained. Heating can be performed using a COP that is much higher than that of the COP in the case of the technique of Patent Document 1 .
Further, for example, the phenomenon of heating the 15 ℃ water to 20 ° C., a phenomenon that heat the 20 ° C. water to 25 ° C., if a phenomenon of heating the 25 ° C. water to 30 ° C. is gradually changed over time switching, COP is It gradually decreases. If COP is high, water can be efficiently heated even if the compression ratio of the compressor is small. While the COP is high, the compression ratio of the compressor may be small. On the other hand, if the compression ratio of the compressor is not increased in response to the decrease in COP, it takes a long time to heat the water to a predetermined temperature. I need it. If the compression ratio of the compressor is increased as the temperature of the water increases, the high heating efficiency by the heat pump can be utilized while suppressing the time until hot water is stored in the hot water tank to a practical level. The advantage of efficiently heating water by the heat pump can be enjoyed effectively.
In the hot water supply device disclosed herein, hot water temperature which has been heated by the heat pump may not be managed. For example, the phenomenon of heating 15 ° C. water to 20 ° C., the phenomenon of heating 20 ° C. water to 25 ° C., and the phenomenon of heating 25 ° C. water to 30 ° C. change over time .

Maintaining the amount of heat exchange in the second heat exchanger at a constant level is equivalent to maintaining the pressurized heat Ru good in the heat pump at a constant level. In this case, the temperature of the hot water heated by the heat pump is not controlled and varies depending on the temperature of the water before being heated by the heat pump. According to this system, for example, the phenomenon of heating 15 ° C. water to 20 ° C., the phenomenon of heating 20 ° C. water to 25 ° C., and the phenomenon of heating 25 ° C. water to 30 ° C. are switched in time series. The hot water storage is completed by proceeding to the phenomenon of heating 40 ° C. water to 45 ° C.
By heat exchange amount in the second heat exchanger to control the operating state of the compressor so as to maintain a constant level, can be the advantages of the heat pump to make the most, to the hot water storage at low running costs It becomes. In order to control the operation state of the compressor so that the heat exchange amount is maintained at a constant level, a program for switching the operation state of the compressor according to the progress of the heating state may be prepared in advance. Feedback control may be performed.
The hot water supply device may include a controller that controls the operation state of the compressor so that the heat exchange amount per unit time in the second heat exchanger is maintained at a constant level.

As described above, the COP decreases as the temperature of the water heated by the heat pump increases. The temperature of the water heated with a heat pump becomes so high that the temperature of the water before heating with a heat pump is high. If the compression ratio of the compressor is increased as the temperature of water sent to the second heat exchanger rises, the heat exchange amount per unit time in the second heat exchanger is maintained at a constant level. Is possible.
Feeding YuSo location may be have a controller that temperature of the water that the water supply to the second heat exchanger to increase the compression ratio of the followers to the compressor to increase.

Further, the sheet YuSo location is initially until a temperature of the water is hot water storage in the lower portion of the hot water storage tank which has been hot-water cold water rises to a predetermined temperature, the amount of water to a multiple of the volume of the hot water storage tank is first It may pass through two heat exchangers . In Patent Document 1 technology, heated while passing through the second heat exchanger, for example a 15 ℃ tap water to 45 ° C.. That is, the amount of water equal to the volume of the hot water tank passes through the second heat exchanger until the temperature of the hot water stored in the lower part of the hot water tank that initially stored the cold water rises to a predetermined temperature. Compared with this hot water supply apparatus , the hot water supply apparatus described above has higher energy efficiency (COP).

The hot water supply apparatus of the present invention heats the water in the hot water tank multiple times with a heat pump. Heat gradually over time. The heat pump exhibits excellent heating efficiency when slightly heating low temperature water. Since the hot water supply apparatus of the invention gradually heats the water in the hot water storage tank step by step with the heat pump, it can effectively enjoy the advantages of the heat pump that efficiently heats the water.
The thermal efficiency of the hybrid hot water supply apparatus can be improved.

The preferred embodiment of this invention is illustrated.
(Form 1)
The hot water supply apparatus according to claim 1, wherein the maximum hot water storage temperature of the hot water storage tank is 50 ° C or lower, the heat medium is an alternative chlorofluorocarbon, and the capacity of the hot water storage tank is about half of the volume of the hot water bath.
When the maximum hot water storage temperature of the hot water storage tank is 50 ° C. or lower, the water can be efficiently heated with a heat pump using an alternative fluorocarbon. In general, hot water supply to a bathtub is large. If the capacity of the hot water storage tank is about half of the volume of the hot water bath, most hot water demands other than hot water filling the bath can be met. By setting the capacity of the hot water storage tank to about half the volume of the bathtub, it is possible to shorten the time until the hot water storage tank is fully stored, and to reduce the size of the hot water supply apparatus.

One embodiment of the hot water supply apparatus of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the hot water supply apparatus 10 includes a heat pump 12, a water supply unit 17, a hot water storage unit 14, a burner 15 unit, a controller 16, and the like.
The heat pump 12 includes an outdoor air heat exchanger (first heat exchanger) 20, a compressor 23, a hot water supply heat exchanger (second heat exchanger) 21, a pressure reducing valve 24, a circulation outward path 30, a circulation return path 31, and the like. Yes.
The outside air heat exchanger 20 includes a heat exchange fan 22, and the heat exchange fan 22 has an electric motor 25 and a fan 26 attached to a drive shaft of the electric motor 25. The fan 26 is driven by the electric motor 25 to rotate. When the fan 26 rotates, outside air is blown to the outside air heat exchanger 20. The outside air heat exchanger 20 performs heat exchange between the heat medium passing through the heat medium flow path 27 provided inside and the outside air. The hot water supply apparatus 10 uses HFC (hydrofluorocarbon) which is a kind of alternative chlorofluorocarbon as a heat medium. A heat medium other than HFC (for example, alternative chlorofluorocarbon other than HFC, carbon dioxide, or the like) can also be used.

The circulation path 30 connects the outlet portion 32 of the heat medium flow path 27 of the outside air heat exchanger 20 and the inlet portion 33 of the heat medium flow path 36 of the hot water supply heat exchanger 21. The compressor 23 is interposed in the circulation outward path 30, compresses the heat medium that has exited the outside air heat exchanger 20, and sends it to the hot water supply heat exchanger 21. A first sensor 37 is attached to the circulation forward path 30 and detects the temperature of the heat medium flowing out from the outside air heat exchanger 20.
The circulation return path 31 connects the outlet part 40 of the heat medium flow path 36 of the hot water supply heat exchanger 21 and the inlet part 34 of the heat medium flow path 27 of the outside air heat exchanger 20. A pressure reducing valve 24 is interposed in the circulation return path 31 and changes the pressure difference between the upstream side and the downstream side by adjusting the opening degree. The pressure reducing valve 24 releases the pressure of the heat medium pressurized by the compressor 23. A second sensor 41 and a third sensor 42 are attached to the circulation return path 31. The second sensor 41 detects the temperature of the heat medium that has flowed out of the hot water supply heat exchanger 21. The third sensor 42 detects the temperature of the heat medium flowing into the outside heat exchanger 20.

The water supply unit 17 includes a first flow path 50, a flow rate sensor 45, a second flow path 54, a relief valve 46, and a fourth sensor 61.
Tap water is supplied to one end 51 of the first flow path 50. The other end 53 of the first flow path 50 is connected in the middle of the second flow path 54. The flow sensor 45 is interposed in the first flow path 50 and detects the amount of water flowing through the first flow path 50.
A relief valve 46 is attached to one end 52 of the second flow path 54. The other end 55 of the second channel 54 is connected to the lower end of a hot water tank 60 (described later). The relief valve 46 opens when the water pressure in the second flow path 54 becomes a predetermined value or more, and releases the pressure in the second flow path 54 to the outside. By providing the relief valve 46, the internal pressure of the hot water storage tank 60 communicating with the second flow path 54 is prevented from becoming excessive. The fourth sensor 61 detects the temperature of the water flowing through the second flow path 54.

The hot water storage unit 14 includes a hot water tank 60, a fifth sensor 72, a first flow rate adjustment valve 48, a third flow path 62, a pump 47, a fourth flow path 67, a sixth sensor 66, a fifth flow path 71, and a seventh sensor. 65, a sixth flow path 73, an eighth sensor 75, a second flow rate adjusting valve 76, a seventh flow path 80, a ninth sensor 81, and the like.
The hot water storage tank 60 is vertically long and has a circular longitudinal cross section in the direction perpendicular to the longitudinal direction. The capacity of the hot water tank 60 is 50 liters. The fifth sensor 72 is attached to the hot water storage tank 60 and detects the temperature of the water therein.
The third flow path 62 connects a portion in the middle of the second flow path 54 and the inlet portion 68 of the water flow path 38 of the hot water supply heat exchanger 21. A pump 47 and a first flow rate adjustment valve 48 are interposed in the third flow path 62. The pump 47 sucks water on the upstream side (first flow rate adjustment valve 48 side) and sends it to the downstream side (hot water supply heat exchanger 21 side). The first flow rate adjustment valve 48 adjusts the amount of water passing therethrough by changing the opening degree.

The fourth flow path 67 connects the outlet portion 70 of the water flow path 38 of the hot water supply heat exchanger 21 and a portion near the hot water storage tank 60 in the middle of the fifth flow path 71. The sixth sensor 66 is interposed in the fourth flow path 67. The sixth sensor 66 detects the temperature of the water flowing through the fourth flow path 67.
The fifth flow path 71 connects the upper end portion of the hot water tank 60 and one end 63 of a burner heat exchanger 69 (described later) provided in the burner portion 15. The seventh sensor 65 is attached to a portion to which the fourth flow path 67 is connected in the middle of the fifth flow path 71, and detects the temperature of the water flowing through the inside.
The sixth flow path 73 communicates with the other end 64 of the burner heat exchanger 69 of the burner portion 15 and the same part as the third flow path 62 in the middle of the second flow path 54. ing. The eighth sensor 75 is attached to the sixth flow path 73 in the vicinity of the other end 64 of the burner heat exchanger 69, and detects the temperature of the water flowing through the inside. The second flow rate adjustment valve 76 is interposed in the sixth flow path 73, and adjusts the amount of water flowing through the sixth flow path 73 by changing its opening degree.
The seventh flow path 80 branches off from a position 82 of the sixth flow path 73 between the portion where the eighth sensor 75 is mounted and the portion where the second flow rate adjustment valve 76 is mounted. The downstream side of the seventh flow path 80 communicates with a hot water tap and a bath. The ninth sensor 81 detects the temperature of the water flowing through the seventh flow path 80.

The burner unit 15 includes a burner heat exchanger 69, a burner 78, and a burner fan 79.
As already described, one end 63 of the burner heat exchanger 69 is connected to the fifth flow path 71. The other end 64 of the burner heat exchanger 69 is connected to the sixth flow path 73. The burner 78 heats the water flowing through the burner heat exchanger 69 by burning the gas. The burner fan 79 blows combustion air to the burner 78.
The controller 16 receives an operation signal generated by operating the remote controller 18 and detection values of the flow sensor 45, sensors 37, 41, 42, 61, 65, 66, 72, 75, and 81. The controller 16 controls the heat exchange fan 22, the compressor 23, the pressure reducing valve 24, the flow rate adjusting valves 48 and 76, the burner 78, and the burner fan 79 by processing those inputs with a stored control program. .

The operation of the hot water supply apparatus 10 will be described.
A liquid heat medium flows from the circulation return path 31 into the heat medium flow path 27 of the outside heat exchanger 20 of the heat pump 12. The heat medium flowing through the heat medium flow path 27 evaporates by absorbing heat from the outside air. The evaporation temperature of the heat medium (HFC) is 10 ° C. Therefore, the temperature of the heat medium flowing out of the heat medium flow path 27 is 10 ° C. Since the heat exchange fan 22 blows outside air to the outside air heat exchanger 20, the heat exchange efficiency of the outside air heat exchanger 20 is improved.
The heat medium flowing out of the heat medium flow path 27 of the outside air heat exchanger 20 flows through the circulation forward path 30 and is compressed by the compressor 23. The temperature of the heat medium compressed by the compressor 23 remains high in the gaseous state. The heat medium whose temperature has increased flows into the heat medium flow path 36 of the hot water supply heat exchanger 21. As will be described in detail later, water having a temperature lower than that of the heat medium passing through the heat medium flow path 36 flows in the water flow path 38 of the hot water supply heat exchanger 21. The heat medium passing through the heat medium flow path 36 is cooled to water passing through the water flow path 38 (by performing heat exchange), and changes from a gaseous state to a liquid state. The water that passes through the water flow path 38 is heated by the heat medium that passes through the heat medium flow path 36, and the temperature rises.
The liquid heat medium flowing out of the heat medium flow path 36 flows through the circulation return path 31. The heat medium flowing through the circulation return path 31 expands (pressure decreases) by passing through the pressure reducing valve 24. The temperature of the expanded heat medium decreases. Then, the heat medium flows from the circulation return path 31 into the heat medium flow path 27 of the outside air heat exchanger 20.
The controller 16 controls the heat exchange fan 22, the compressor 23, and the pressure reducing valve 24 based on the heat medium temperature detected by the sensors 37, 41, 42, thereby providing the parts where the sensors 37, 41, 42 are provided. Is adjusted to a desired value.

The operation of storing hot water in the hot water storage tank 60 will be described with reference to FIGS. 1, 2, and 3. At this time, the hot-water tap has not been opened or the bath has not been filled. That is, it is assumed that water does not flow out of the hot water supply apparatus 10 through the seventh flow path 80. The flow path filled in FIG. 1 indicates that the heat medium and water are circulating. The direction of circulation of the heat medium and water is indicated by arrows.
When the first flow rate adjustment valve 48 of the hot water storage unit 14 is opened and the pump 47 is driven, water is sucked into the second flow path 54 from the lower part of the hot water storage tank 60. The water sucked into the second flow path 54 passes through the third flow path 62 and flows into the water flow path 38 of the hot water supply heat exchanger 20. The water passing through the water flow path 38 is heated by the high-temperature heat medium flowing through the heat medium flow path 36 and the temperature rises. The water whose temperature has risen flows through the fourth flow path 67 and returns to the upper part of the hot water tank 60 through a part of the fifth flow path 71. When the water sucked out from the hot water storage tank 60 passes through the hot water supply heat exchanger 20, the temperature rises and the circulation returning to the hot water storage tank 60 is repeated, whereby hot water (hot water) is stored in the hot water storage tank 60. The

The process of storing hot water in the hot water storage tank 60 and the COP (energy consumption efficiency) of the heat pump 12 in the middle thereof will be described with reference to FIG. Note that the temperature of the water in the hot water storage tank 60 at the start of hot water storage is 15 ° C.
The leftmost column in FIG. 2 indicates the number of times of water circulation in the hot water tank 60. For example, the amount of water in the hot water tank 60 is first sucked out, and the middle of all the water returning to the hot water tank 60 is counted as the first circulation.
The column on the right side of the number of circulations and the column on the right side show the hot water supply heat exchange heat medium outflow temperature and the outdoor air heat exchange medium inflow temperature, respectively. The hot water supply heat exchange medium outflow temperature is the temperature of the heat medium flowing out from the heat medium flow path 36 of the hot water supply heat exchanger 21, that is, the temperature of the heat medium detected by the second sensor 41. The outside air heat exchange medium inflow temperature is the temperature of the heat medium flowing into the outside air heat exchanger 20, that is, the temperature of the heat medium detected by the third sensor 42. The temperature of the heat medium is lower than the outside air (assuming that it is 10 ° C.).
As shown in FIG. 2, the hot water supply heat exchange heat medium outflow temperature is changed by 6 ° C. every time the water in the hot water storage tank 60 circulates once. For example, the hot water supply heat exchange medium outflow temperature is 22.8 ° C. at the first circulation, and is changed to 28.8 ° C. at the second circulation. The hot water supply heat exchange medium outflow temperature is changed by increasing the compression ratio of the compressor 23 (increasing operating strength) and adjusting the opening of the pressure reducing valve 24. The inflow temperature of the outside heat exchange medium is constant regardless of the number of circulations. Therefore, the difference between the hot water heat exchange heat medium outflow temperature and the outside air heat exchange medium inflow temperature increases by 6 ° C. every time the circulation number increases.
The timing for increasing the compression ratio of the compressor 21 may not be performed for each circulation. During the hot water storage, the compression ratio of the compressor can be gradually increased.

The right-hand column and the right-hand column of the outside air heat exchange medium inflow temperature indicate the hot water supply heat exchange water inflow temperature and the hot water supply heat exchange water outflow temperature, respectively. The hot water supply heat exchange water inflow temperature is the temperature of water sucked out from the hot water storage tank 60 and flowing into the water flow path 38 of the hot water supply heat exchanger 21. The hot water supply hot water inflow temperature is detected by the fourth sensor 61. The fourth sensor 61 is mounted in the vicinity of the other end 55 of the second flow path 54 and is positioned apart from the portion (inlet portion 68) where water flows into the hot water supply heat exchanger 21. Since the temperature difference of the water flowing through this part is slight, the detected value can be used as the hot water supply hot water inflow temperature. As will be described in detail later, the fourth sensor 61 is also used to detect the temperature when water is supplied to the hot water tank 60. The hot water supply heat exchange water outflow temperature is the temperature of water flowing out of the water flow path 38 of the hot water supply heat exchanger 21 and returning to the hot water storage tank 60. The hot water supply hot water outflow temperature is detected by the sixth sensor 66.
For example, in the middle of the first circulation, the water before heating that has been put in the hot water storage tank 60 flows into the hot water supply heat exchanger 21, so the hot water supply heat exchange water inflow temperature is 15 ° C. Since the water flowing into the hot water supply heat exchanger 21 is heated and its temperature rises, the hot water supply heat exchange water outflow temperature becomes 21 ° C. When the first circulation is completed, all the water in the hot water storage tank 60 becomes 21 ° C. Then, in the second circulation, the water flows into the hot water supply heat exchanger 21, so the hot water supply heat exchange water inflow temperature is 21 ° C.

The temperature difference between the hot water supply hot water inflow temperature and the hot water supply heat exchange water outflow temperature does not change for each circulation. For example, in the first circulation, the hot water hot water exchange water inflow temperature is 15 ° C., and the hot water hot water exchange water outflow temperature is 21 ° C. Therefore, the temperature difference between the hot water hot water exchange water inflow temperature and the hot water hot water exchange water outflow temperature is 6 ° C. For example, in the fourth circulation, the hot water hot water exchange water inflow temperature is 33 ° C., and the hot water hot water exchange water outflow temperature is 39 ° C. Accordingly, even in this case, the temperature difference between the hot water hot water exchange inflow temperature and the hot water hot water exchange outflow temperature is 6 ° C.
By changing the hot water supply heat exchange medium outflow temperature by 6 ° C. every time the circulation is performed, the hot water supply heat exchange water outflow temperature is also increased by 6 ° C. each time. For example, at the second circulation, the hot water heat exchange water outflow temperature is 27 ° C., and at the third circulation, it is 33 ° C., 6 ° C. higher than that. When the fifth circulation cycle is completed, all the water in the hot water tank 60 becomes 45 ° C.

The amount of heat exchange is shown in the column on the right side of the hot water supply hot water outflow temperature. The amount of heat exchange means the amount of heat exchange between the heat medium and water performed in the hot water supply heat exchanger 21. As described above, the temperature difference between the hot water heat exchange water inflow temperature and the hot water heat exchange water outflow temperature does not change every time the water in the hot water tank 60 is circulated. Accordingly, the heat exchange amount is also constant throughout the first to fifth circulations.
The heat exchange amount (Q) is given by the following equation.
Q = c × W × Δt;
“C” is the specific heat of water, and “c = 4.19 kJ / (kg · K)”.
“W” is the amount of water passing through the hot water supply heat exchanger 21. Since the capacity of the hot water tank 60 is 50 liters, “W = 50 kg”.
“Δt” is a temperature difference between the hot water hot water exchange inflow temperature and the hot water hot water exchange water outflow temperature. Therefore, “Δt = 6 ° C.”.
From the following equation, “1257 kJ” is obtained as the heat exchange amount.
Q = 4.19 × 50 × 6 = 1257 kJ;

In the column on the right side of the heat exchange amount, the power consumption (compressor power consumption) of the compressor 23 is shown in units of “Wh” and “kJ”. As apparent from this column, the power consumption of the compressor increases as the number of water circulations in the hot water tank 60 increases. This is because, as the number of circulations increases, the compressor 23 needs to compress the heat medium higher in order to increase the outlet temperature of the hot water supply water by increasing its outlet temperature.
In the column on the right side of the compressor power consumption, the COP of the heat pump 12 (heat pump COP) is shown. The heat pump COP is obtained by dividing the heat exchange amount by the compressor power consumption. For example, at the third circulation, the compressor power consumption is “140.4 kJ”. Since the heat exchange amount is “1257 kJ”, the heat pump COP is as follows.
COP (third time) = 1257 / 140.4 = 8.95;
Further, since the total heat exchange amount is “6285 kJ” and the total power consumption of the compressor is “712.8 kJ”, the total heat pump COP is as follows.
COP (total) = 6285 / 712.8 = 8.82;

  FIG. 3 is a graph showing the relationship between the difference (T1−T2) between the hot water supply heat exchange medium outflow temperature (T1) and the outside air heat exchange medium inflow temperature (T2) and the heat pump COP. The heat pump COP decreases as the difference between the hot water heat exchange heat medium outflow temperature and the outside air heat exchange heat medium inflow temperature increases. The hot water supply apparatus 10 of the present embodiment increases the hot water supply heat exchange medium outflow temperature by 6 ° C. by increasing the compressor 23 each time the water in the hot water tank 60 circulates (higher in steps). To do). For this reason, when the number of circulations is small, that is, when the difference between the hot water supply heat exchange heat medium outflow temperature and the outside air heat exchange heat medium inflow temperature is small, a high heat pump COP can be obtained. Therefore, as shown in FIG. 2, the excellent energy efficiency that the total heat pump COP is “8.82” is realized.

As described above, the hot water supply apparatus 10 of the present invention increases the difference between the hot water heat exchange heat medium outflow temperature and the outdoor air heat exchange medium inflow temperature each time the water in the hot water tank 60 circulates, and finally 45 Store the water of ℃ in the hot water tank 60.
On the other hand, in the conventional hot water supply apparatus, the water in the hot water tank is not circulated more than once in the process of increasing the temperature of the water in the hot water tank. The reason why the water in the hot water tank is not circulated at least once is that it is desired to form a high temperature stratification above the hot water tank. Therefore, for example, when 45 ° C. water is finally stored in the hot water storage tank, the 45 ° C. temperature stratification gradually descends in the hot water storage tank. If a high temperature stratification is formed on a low temperature stratification, hot water can be supplied using the high temperature stratification even if all the water in the hot water storage tank is not hot. However, in that case, in order to create a temperature stratification of 45 ° C., it is necessary to perform a high compression operation from the start of hot water storage, as in the fifth cycle of the circulation in FIG. Therefore, the low energy efficiency that the heat pump COP is “5.72” must be satisfied.

The operation when the hot water supply apparatus 10 performs hot water supply will be described for each of the following cases (1), (2), and (3).
(1) When the temperature of the hot water stored in the hot water storage tank 60 is higher than the required hot water supply temperature.
As shown in FIG. 4, it is assumed that 45 ° C. water is stored in the hot water tank 60 and the required hot water supply temperature is 38 ° C. The required hot water supply temperature is set by the user operating the remote controller 18.
A water pressure of tap water is applied to the first flow path 50. For this reason, when the hot-water tap is opened or the bath is filled with water, water flows out from the seventh flow path 80. In order to compensate for the outflowed water, the water flows into the first flow path 50 of the water supply unit 17. The flow rate of water flowing through the first flow path 50 is detected by the flow rate sensor 45. The water that has flowed into the first flow path 50 flows through the second flow path 54 and also flows into the third flow path 62 and the sixth flow path 73 along the way.
The amount of water that has flowed through the second flow path 54 and did not flow into the third flow path 62 and the sixth flow path 73 is supplied to the hot water storage tank 60. The temperature of the supplied water is detected by the fourth sensor 61. By supplying water to the hot water storage tank 60 from the second flow path 54, 45 ° C. water is sent from the upper part of the hot water storage tank 60 to the fifth flow path 71.

On the other hand, the water flowing into the third flow path 62 from the second flow path 54 passes through the opened first flow rate adjustment valve 48 and the pump 47 that is not driven. The heat pump 12 is in operation. The water flowing through the third flow path 62 is heated by passing through the hot water supply heat exchanger 21 and flows into the fourth flow path 67. At this time, the temperature of the water flowing through the fourth flow path 67 is adjusted to 38 ° C., which is the same as the required hot water supply temperature. Specifically, the detection temperature of the sixth sensor 66 provided in the fourth flow path 67 is set to 38 ° C. In adjusting the temperature of the water flowing through the fourth flow path 67, the compression ratio of the compressor 23, the opening degree of the pressure reducing valve 24, and the opening degree of the first flow rate adjusting valve 48 are adjusted.
38 ° C. water flowing through the fourth flow path 67 is mixed with 45 ° C. water fed from the hot water tank 60 and flowing through the fifth flow path 71. Therefore, the temperature of the water flowing through the fifth flow path 71 and flowing into the burner heat exchanger 69 of the burner section 15 is a value between 38 ° C. and 45 ° C. The burner 78 is not operating. For this reason, water having a temperature between 38 ° C. and 45 ° C. flows from the burner heat exchanger 69 into the sixth flow path 73. Hereinafter, the water flowing into the sixth flow path 73 from the burner heat exchanger 69 is referred to as “burner outflow water”.
The burner outflow water merges with the water flowing into the sixth flow path 73 from the second flow path 54 (hereinafter referred to as “tap mixed water”), and is adjusted to 38 ° C., which is the required hot water supply temperature. In the adjustment, the opening degree of the second flow rate adjustment valve 76 changes based on the detected temperatures of the eighth sensor 75 and the ninth sensor 81. The water adjusted to 38 ° C. flows through the seventh flow path 80 and is supplied to a hot water tap or a bath.

  As described above, 38 ° C. water heated by the heat pump 12 is mixed with 45 ° C. water fed from the hot water tank 60. For this reason, the amount of water (hot water) delivered from the hot water tank 60 can be saved. The temperature of the water heated with the heat pump 12 can also be made into 38 degreeC or more. In this case as well, the amount of water delivered from the hot water tank 60 can be saved, but the heat pump COP is lowered. The temperature of the water heated with the heat pump 12 can also be made into 38 degrees C or less. In this case, if the temperature at which the water fed from the hot water tank 60 and the water heated by the heat pump 12 are mixed is higher than the required hot water supply temperature, the amount of water sent from the hot water tank can be saved. At the same time, the heat pump COP becomes higher.

(2) When the temperature of the hot water stored in the hot water storage tank 60 is lower than the required hot water supply temperature.
As shown in FIG. 5, it is assumed that the hot water tank 60 is filled with 15 ° C. water, that is, water having the same temperature as tap water. Such a state occurs when all of the hot water (hot water) stored in the hot water storage tank 60 is consumed. It is assumed that the required hot water supply temperature is 42 ° C. In this case, the second flow rate adjustment valve 76 interposed in the sixth flow path 73 is fully closed. For this reason, the water that flows into the second channel 54 from the first channel 50 is supplied to the hot water storage tank 60 and also flows into the third channel 62. By supplying water from the second flow path 54 to the hot water storage tank 60, water at 15 ° C. is sent from the hot water storage tank 60 to the fifth flow path 71. The heat pump 12 is operating at a low compression (operating weakly). The water flowing into the third flow path 62 is heated by passing through the hot water supply heat exchanger 21, reaches a temperature of 21 ° C., and flows into the fourth flow path 67.
In addition, even if the heat pump 12 is a high compression operation, it cannot respond to a hot water supply request by itself. As described above, the heat pump 12 has the ability to store 45 ° C. water in the hot water storage tank 60, but this is possible by storing hot water over time. Therefore, when the temperature of the hot water stored in the hot water storage tank 60 is lower than the required hot water supply temperature, the burner unit 15 needs to be operated.

The 21 ° C. water flowing through the fourth flow path 67 joins the 15 ° C. water fed from the hot water tank 60 and flowing through the fifth flow path 71. Therefore, the temperature of the water flowing through the fifth flow path 71 and flowing into the burner heat exchanger 69 of the burner unit 15 becomes a value between 15 ° C and 21 ° C. The burner 78 heats the burner heat exchanger 69 by burning gas. The temperature of the burner effluent becomes 42 ° C. by adjusting the heating intensity. The burner effluent further flows into the seventh flow path 80. Therefore, hot water supply at 42 ° C. is performed from the seventh flow path 80 to the hot water tap or the like.
The heat pump 12 can realize a high heat pump COP in a state of low compression operation. Accordingly, even when the burner 78 is burned, the energy efficiency of the hot water supply apparatus 10 is improved as a whole when the heat pump 12 is operated with a high heat pump COP in addition to the combustion of the burner 78 alone. Can do.

(3) When the burner 78 heats the water sent out from the hot water storage tank 60 with minimum combustion, the temperature of the burner outflow water exceeds the hot water supply required temperature.
When the burner 78 is minimum-combusted, the phenomenon that the temperature of the burner effluent water exceeds the required hot water supply temperature occurs when the temperature of the hot water stored in the hot water storage tank 60 is slightly lower than the required hot water supply temperature. “Minimum combustion” refers to a state in which the burner 78 is burning the weakest.
As shown in FIG. 6, it is assumed that 38 ° C. water is stored in the hot water storage tank 60 and the required hot water supply temperature is 42 ° C. Since the temperature of the water stored in the hot water storage tank 60 is lower than the required hot water supply temperature, the burner 78 must be burned.

When the burner 78 is minimum-combusted, the second flow rate adjustment valve 76 interposed in the sixth flow path 73 is opened when the temperature of the burner effluent water exceeds the required hot water supply temperature. Therefore, the water that has flowed into the second flow path 54 from the first flow path 50 also flows into the third flow path 62 and the sixth flow path 73 along the way. The heat pump 12 is operated at a low compression. The water flowing into the third flow path 62 is heated by passing through the hot water supply heat exchanger 21, reaches a temperature of 21 ° C., and flows into the fourth flow path 67.
The water that has passed through the fourth flow path 67 merges with the 38 ° C. water fed from the hot water storage tank 60 through the fifth flow path 71. Therefore, the temperature of the water flowing through the fifth flow path 71 and flowing into the burner heat exchanger 69 of the burner unit 15 becomes a value between 21 ° C. and 38 ° C. Here, the temperature of the water flowing into the burner heat exchanger 69 is assumed to be 35 ° C. When the burner heat exchanger 69 is heated by the burner 78, the temperature of the burner effluent becomes 45 ° C. The burner effluent is mixed with tap water. The amount of the tap water is adjusted by the second flow rate adjustment valve 76. Hot water at 42 ° C. is supplied from the seventh flow path 80 to the hot water tap or the like by mixing the burner effluent water and the tap water mixed in the amount of water.

The amount of hot water supplied from the seventh flow path 80 is regulated by the opening of the hot water tap and the amount of hot water filled in the bath. Therefore, the amount of water fed from the hot water storage tank 60 can be saved by increasing the amount of tap water as much as possible than the amount of burner effluent.
As described above, by performing the low compression operation of the heat pump 12, 21 ° C. water can be mixed with the 38 ° C. water fed from the hot water storage tank 60. Therefore, the temperature of the water flowing into the burner unit 15 becomes higher than mixing 15 ° C. water which is the temperature of tap water. For this reason, the temperature of burner effluent water also becomes high. Therefore, in order to maintain 42 degreeC which is hot water supply request | requirement temperature, you have to increase the amount of tap water mixed water. Therefore, the amount of water delivered from the hot water tank 60 can be saved. When the heat pump 12 is operated at high compression, the heat pump COP decreases, but the amount of water sent out from the hot water storage tank 60 can be saved.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

System diagram of hot water supply system (during hot water storage). The table | surface which shows the temperature etc. of each site | part in hot water storage. The graph which shows COP of a heat pump. System diagram of hot water supply system (hot water storage temperature> required hot water supply temperature). System diagram of hot water supply system (hot water storage temperature <required hot water supply temperature). System diagram of the hot water supply system (state where the burner is burning at the minimum).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Hot water supply apparatus 12: Heat pump 14: Hot water storage part 15: Burner part 16: Controller 17: Water supply part 18: Remote control 20: Outside air heat exchanger 21: Hot water heat exchanger 22: Heat exchange fan 23: Compressor 24: Pressure reducing valve 25: Electric motor 26: Fan 27: Heat medium flow path 30: Circulation forward path 31: Circulation return path 32: Outlet part 33, 34: Inlet part 36: Heat medium flow path 37: First sensor 38: Water flow path 40: Outlet part 41: 2nd sensor 42: 3rd sensor 45: Flow sensor 46: Relief valve 47: Pump 48: 1st flow regulating valve 50: 1st flow path 51, 52: One end 53: Other end 54: 2nd flow path 55 : Other end 60: hot water tank 61: fourth sensor 62: third flow path 63: one end 64: other end 65: seventh sensor 66: sixth sensor 67: fourth flow path 68: inlet 69: burner heat exchange Device 70: outlet portion 71: fifth flow path 2: Fifth sensor 73: 6 passage 75: 8 sensor 76: second flow rate adjustment valve 78: Burner 79: Burner fan 80: 7 passage 81: 9 sensor

Claims (1)

The heat medium is “a first heat exchanger that exchanges heat between the heat medium and the outside air, a compressor that compresses the heat medium, a second heat exchanger that exchanges heat between the heat medium and water, A heat pump that circulates through a passage that goes through a pressure reducing valve that releases pressure,
A hot water tank,
A water circulation pump for feeding water from the lower part of the hot water tank to the second heat exchanger and returning water heated by the second heat exchanger to the upper part of the hot water tank;
A burner that heats the water delivered from the top of the hot water tank when necessary;
All of the water in the hot water tank and have a controller to warm to a temperature of stepwise target cycled several times to the second heat exchanger,
The controller maintains the amount of heat exchange in the second heat exchanger at a constant level by increasing the compression ratio of the compressor every time all the water in the hot water tank passes through the second heat exchanger. The hot water supply apparatus is characterized in that water is raised by the same temperature at each of the plurality of times .

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