JP3443702B2 - Heat pump water heater - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump water heater, and more particularly to a heat pump water heater using a carbon dioxide gas refrigerant used in a hot water supply system that enables efficient and stable hot water supply throughout the year.

[0002]

2. Description of the Related Art In a heat pump water heater, a target high-pressure side refrigerant amount fluctuates due to fluctuations in the low-pressure side refrigerant amount due to fluctuations in season (air temperature). That is, in the low temperature outside air in winter, the pressure decreases as the evaporation temperature decreases, and the gas becomes a lean gas. Therefore, if the amount of the refrigerant in the refrigeration cycle is constant, it is natural that the corresponding amount of the refrigerant moves to the high pressure side, the gas density in the high pressure space increases, and the high pressure also increases.

Particularly, in a system in which a low-pressure side refrigerant receiver is provided between a compressor or a refrigerant heat exchanger and an evaporator, the refrigerant gas sucked into the compressor has a low superheat degree, becomes moist, and has a low discharge. The gas temperature is likely to be reached, an appropriate discharge gas temperature and hot water discharge cannot be obtained, and efficient hot water supply cannot be achieved.

On the contrary, in the heat pump operation in summer, the refrigerant distribution in the heat pump operation is high in temperature and the evaporation temperature (low pressure) is increased, so that the refrigerant density in the low pressure space is increased and the weight ratio of the refrigerant in the low pressure space is increased. The amount of refrigerant on the side becomes insufficient and the high pressure tends to be low.

Therefore, if the optimum amount of refrigerant is filled in the closed cycle for the summer operation, the high pressure may rise too much in the winter and the refrigeration cycle may not work. In other words, an excessive amount of refrigerant is present on the high pressure side, which causes an abnormally high pressure before heat exchange, so the operation will be stopped by a protective device designed below the design pressure, or the coefficient of performance will drop due to unnecessary high pressure. Cause. Especially, the hot water supply load is larger in winter and the operation time is longer. Further, even when storing hot water, it is usually required to store high temperature hot water, and the high pressure tends to be naturally high.

By the way, in a conventional heat pump water heater, a CFC refrigerant is mainly used as a refrigerant used. Since this CFC refrigerant has a high critical point and a low pressure, even if the high pressure in the high pressure space rises in winter, there was no particular problem, and there was no particular problem in operation. However, recently, the harmful effects of CFCs on the global environment have been taken up, and the use of carbon dioxide (CO ₂ ) as an eco-friendly refrigerant has been rapidly promoted, and heat pumps using carbon dioxide refrigerant that had never been provided so far. Water heaters have been considered.

[0007]

However, the carbon dioxide gas refrigerant has a lower critical point and a pressure several times higher than that of the conventional CFC refrigerant, and when the high pressure space in the conventional CFC refrigerant is used as it is, In winter, pressure increases,
There is a risk that the energy at breakage will become large if the existing amount on the high voltage side becomes large. Of course, as a structure capable of withstanding the high pressure, it is conceivable to increase the thickness of the pipe, for example, but this is not preferable because the cost becomes large. Therefore, it was sought to reduce both the corner and the high pressure space on the low pressure side as much as possible from the viewpoint of safety, and narrow the space. However, if the high-pressure side space is made narrower, it will be more easily affected by the low-pressure side space and will be affected by the temperature.

In view of the above situation, the present invention focuses on the fact that the amount of gas present changes in the low pressure side space depending on winter and summer when the amount of refrigerant in the refrigeration cycle is constant in order to cope with this. By finding that the difference in the amount of gas is pooled as a cushion, the heat pump water heater for carbon dioxide gas, which requires different amounts of refrigerant in summer and winter in a refrigeration cycle with less refrigerant space on the high pressure side, is more suitable for an inexpensive refrigerant cycle. The purpose of the invention is to keep the amount of refrigerant and to supply hot water at a stable constant temperature safely throughout the year.

In the supercritical vapor compression cycle,
The high side pressure is controlled by adjusting the amount of circulating refrigerant, and the cooling capacity is adjusted by, for example, Japanese Patent Publication No. 7-18.
No. 602 and the like. However, although these technologies are discussed focusing on the cooling capacity, they are not focused on hot water supply using the gas cooler heat radiation on the high pressure side as water heating, and the hot water outlet temperature according to the temperature is not discussed.

[0010]

One of the features of the present invention that meets the above object and achieves the object is that a compressor, a gas cooler, a refrigerant heat exchanger, a refrigerant expansion valve, and an evaporator are sequentially arranged by a refrigerant pipe. , A heat pump water heater that connects and installs an accumulator on the suction side of the compressor to let water flow through a countercurrent gas cooler to raise the temperature, and branches from the middle of the piping from the discharge side of the compressor to the gas cooler to defrost solenoid valve. The refrigerant control circuit further downstream of the refrigerant expansion valve, and the refrigerant control downstream of the second buffer electromagnetic valve from the second buffer electromagnetic valve via the first buffer electromagnetic valve and the refrigerant buffer by further branching before the defrost electromagnetic valve. A control circuit reaching the circuit merging section and a refrigerant control circuit reaching the refrigerant expansion valve upstream from the middle of the control circuit are respectively provided to operate either or both of the first and second buffer solenoid valves. Ri recovery or refrigerant of the refrigeration cycle in the refrigerant buffer, or in point occupies possibly adjust the necessary refrigerant amount is filled in the refrigerating cycle.

The invention of claim 2 is another heat pump water heater having the same object and problem.
In a heat pump water heater that sequentially connects a gas cooler, a refrigerant heat exchanger, a refrigerant expansion valve, and an evaporator with a refrigerant pipe, arranges an accumulator on the compressor suction side, and passes water through a countercurrent gas cooler to raise the temperature. , A refrigerant control circuit that branches from the middle of the piping from the compressor discharge side to the gas cooler and reaches the refrigerant expansion valve downstream from the defrost electromagnetic valve, and the refrigerant expansion valve downstream from the refrigerant buffer equipped with a heater via the buffer electromagnetic valve A refrigerant control circuit reaching the refrigerant control circuit merging portion and a refrigerant control circuit reaching the refrigerant expansion valve upstream from the middle of the control circuit are respectively provided, and the refrigerant of the refrigeration cycle is supplied to the refrigerant buffer by operating the buffer solenoid valve of the control circuit. It is characterized in that the refrigerant can be collected or charged with a heater to fill the refrigeration cycle to adjust the required amount of refrigerant.

[0012] Claims 3 to 5 are more specific aspects of the above heat pump water heater. In the invention of claim 3, an accumulator is arranged on the suction side of the compressor, and the high pressure side of the refrigerant heat exchanger is at the gas cooler outlet and the low pressure side is at low pressure. It is characterized in that it is installed so that the side is between the air heat exchanger and the accumulator.

The invention of claim 4 uses a countercurrent type heat exchanger such as a double type heat exchanger in which the amount of refrigerant on the high pressure side is small, as the countercurrent type gas cooler. Each is characterized in that the adjustment is performed by adjusting the feed water flow rate by adjusting a flow rate control valve or a variable flow rate pump.

[0014]

In the above heat pump water heater of the present invention, when the second buffer solenoid valve of the refrigeration cycle is opened in FIG. 1, the low-pressure refrigerant liquid can be collected in the buffer (refrigerant receiver) from point A to point C in the figure. it can. Further, the refrigerant liquid on the high pressure side can be collected in the buffer through the points C to B on the high pressure side.

On the other hand, by opening the first buffer solenoid valve and applying the discharge pressure of the compressor, which is the maximum pressure of the refrigeration cycle, inside the buffer, the internal refrigerant liquid can be discharged toward points A and B. it can. Normally, the optimum amount of refrigerant when operating at ambient temperature is different in winter (-8 ° C) and summer (+ 35 ° C), and although there is a difference in the amount of refrigerant, the amount of refrigerant is controlled by opening and closing the buffer solenoid valve, It is possible to adjust the pressure and temperature at the high pressure side gas cooler inlet / outlet on the target refrigerant cycle for heating the hot water supply to be optimal.

Further, in the refrigeration cycle diagram of FIG. 2, when the buffer solenoid valve is opened, the low pressure refrigerant liquid can be collected in the buffer from the point A through the point C as in the case of FIG. 1, or the point B on the high pressure side. Through the point C, the high pressure side refrigerant liquid can be collected in the buffer.

On the other hand, when the buffer solenoid valve is opened and the heater is energized and heated, the refrigerant liquid inside the buffer evaporates, the internal pressure rises, and the inside refrigerant liquid is discharged toward points A and B. In combination with the opening of the solenoid valve, it becomes possible to adjust the target properness and the amount of refrigerant at the pressure and temperature, and it is possible to supply hot water at a constant temperature regardless of temperature fluctuations.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of the heat pump water heater of the present invention will be described below with reference to the refrigeration cycle shown in the accompanying drawings.

FIG. 1 is a refrigeration cycle diagram of the first embodiment of the heat pump water heater of the present invention. In the figure, 1 is a compressor, 2 is a gas cooler, 3 is a refrigerant heat exchanger, 4 is a refrigerant expansion valve, and 5 is a refrigerant expansion valve. An evaporator (air heat exchanger), 6 is a blower, and 7 is an accumulator, and these compressor 1, gas cooler 2, refrigerant heat exchanger 3, refrigerant expansion valve 4, evaporator 5 are connected to refrigerant pipes T ₁ , T _2. And the refrigerant heat exchanger 3
In, the high pressure side pipe T ₁ and the low pressure side pipe T ₂ are subjected to countercurrent heat exchange, and the accumulator 7 is arranged on the compressor suction side to form a basic series of refrigeration cycles. Attaches a blower 6 for flowing air through it to serve as a heat source for the refrigerant heat exchanger.
Is a counter-current type gas cooler, and a water supply pipe T ₃ from the water inlet 13 to the hot water supply water outlet 14 is inserted in a countercurrent state, and a water pump 15 and a proportional valve 16 are installed in the water supply pipe T ₃ on the water inlet side. This forms the hot water supply system passage. Here, the accumulator 7 is provided because if the refrigerant liquid in the evaporator 5 cannot be heated and evaporated by the refrigerant heat exchanger 3, if the compressor 1 instantly sucks it in as a liquid, it will be compressed and broken. It is a low-pressure side protection space that is usually filled with superheated gas that does not contain liquid.

According to the present invention shown in FIG. 1, however, in the above basic refrigeration cycle, the pipe branches from the discharge side of the compressor 1 to the gas cooler 2 and branches from the defrost electromagnetic valve 8 to the downstream expansion point A of the refrigerant expansion valve 4. Piping T _{4 of the} refrigerant circuit to reach,
The second buffer solenoid valve 1 is routed through a pipe T ₅ that branches further from the branch portion of the pipe T ₄ and the defrost solenoid valve 8 to reach the buffer 10 from the first buffer solenoid valve 9.
A pipe T ₆ to form a control circuit extending from 1 to merging portion A of the refrigerant expansion valve 4 downstream of the refrigerant circuit piping T _4, the branch from point C between the second buffer solenoid valve 11 and the merging section A The refrigerant circuit pipes T ₇ reaching the point B upstream of the refrigerant expansion valve 4 are respectively provided. In the figure, 12 and 12 'are strainers having a role of a filter for preventing dust and foreign matter from being caught in the valve. The defrost electromagnetic valve 8 is a valve that opens when frost adheres to the evaporator 5 when the frost is melted by the high-temperature discharge gas.

Next, a case where hot water is supplied by the heat pump water heater having the above refrigeration cycle will be described. Usually, the evaporation temperature of the refrigerant in the evaporator is 10 to 10
15 ° C lower. That is. Since the evaporation temperature (constant pressure) is almost determined by the air temperature, the density of the refrigerant sucked into the compressor and circulated is determined, and the refrigerant circulation amount is determined.

When a gas having a proper suction superheat degree, that is, a temperature 5 to 10 ° C. higher than the evaporation temperature is sucked into the compressor, the temperature of the gas discharged from the compressor is appropriate and the high pressure at that time is high. Is determined to be a stable constant value. The higher the high pressure, the higher the discharge gas temperature. When the discharge gas temperature and the high pressure are determined, the enthalpy on the discharge side can be determined. Since the discharge side of the compressor is connected to the gas cooler inlet,
The enthalpy at the gas cooler inlet is approximately equal to the enthalpy at the compressor discharge.

The temperature of the refrigerant at the outlet of the gas cooler can be adjusted to be 5 to 10 ° C. higher than the normal feed water temperature, depending on the feed water temperature. In this way, a high pressure that is approximately equal to the gas cooler outlet temperature of the refrigerant and the inlet pressure is determined, and the gas cooler outlet enthalpy can also be determined. The heating capacity is the difference between the inlet and outlet enthalpies of the gas cooler multiplied by the refrigerant circulation amount. Therefore, the larger the refrigerant circulation amount and the larger the enthalpy difference, the larger the heating capacity. The amount of heat of water heated by exchanging heat with the refrigerant in the gas cooler is almost equal to this heating capacity. Since the water supply temperature is usually almost constant depending on the season and temperature, the hot water temperature changes depending on the water flow rate. That is, if a small amount of water is supplied, the hot water temperature rises, and if the amount of water is increased, the hot water temperature decreases. In this way, the hot water outlet temperature can be adjusted by adjusting the feed water flow rate by adjusting the flow rate control valve or the variable flow rate pump. In this way, when the air temperature is determined, the expansion valve can adjust and control the refrigerant supply amount so that the compressor intake gas temperature becomes an appropriate superheat degree, so the hot water supply heating capacity is almost automatically determined.

By the way, the above logic is premised on proper high pressure and low pressure. If the low pressure is properly designed, the evaporation temperature (low pressure) can be determined by the temperature as described above. The amount of refrigerant that can be evaporated can be automatically controlled by the expansion valve so as to have an appropriate degree of superheat.

The high pressure is related to the heat dissipation capacity of the gas cooler. As described above, this heat dissipation capacity balances with the refrigerant heating capacity, which is the product of the refrigerant circulation amount and the high-pressure side enthalpy difference. In order to maintain the balance, a temperature difference is required between the refrigerant side temperature and the water side temperature via the heat exchange surface. This temperature difference is basically determined by the heat transfer performance on the refrigerant gas side, the heat transfer performance on the water side, and the heat transfer area as a heat exchanger. However, if the proper amount of refrigerant is not filled in the closed cycle, the refrigeration cycle will not work. If there is an excessive amount of refrigerant on the high pressure side, the pressure will become abnormally high before heat exchange, so operation will be stopped due to the protective device set below the design pressure, and unnecessary high pressure increase will result in a decrease in the coefficient of performance. Cause. If the amount of refrigerant is too small, an appropriate amount of refrigerant cannot be automatically supplied to the evaporator by the expansion valve, and the evaporation temperature (low pressure) is abnormally lowered, which causes a decrease in the coefficient of performance.

As described above, the refrigerant evaporation temperature in the evaporator is usually 10 to 15 ° C. lower than the atmospheric temperature. In other words, since the evaporation temperature (low pressure) is almost determined by the air temperature,
The amount of refrigerant present in the low pressure side of the refrigerant heat exchanger, the accumulator, and the low pressure chamber inside the compressor can be determined from the density of the refrigerant at the pressure and temperature. Also for the high-pressure side gas cooler and the high-pressure side of the refrigerant heat exchanger, it is possible to obtain the amount of the refrigerant at the target proper pressure and temperature.

Table 1 below shows an example of the refrigerant distribution amount on the low pressure side and the high pressure side according to the seasonal (air temperature) fluctuation of the refrigeration cycle of the tested CO ₂ heat pump water heater. Since the gas cooler was a double-tube countercurrent heat exchanger, the space on the high-pressure side was much smaller than that on the low-pressure side. The space specifications are as follows. The gas cooler of the tester has a copper pipe with an inner diameter of 4.8 mm and a length of 23 m as the heat transfer tube, the refrigerant space is about 0.4 liters, the high pressure part of the compressor is about 0.2 liters, the refrigerant heat exchanger. And the pipe have a volume of less than 0.2 liters, and the total high-pressure space is about 0.8 liters. On the other hand, the low pressure part of the compressor is 5 liters, the air heat exchanger serving as an evaporator is 1.1 liters, the accumulator is 1.9 liters, and the total low pressure space is about 8 liters.

[0028]

[Table 1]

The optimum amount of refrigerant when operating at these temperatures is considered to be as shown in this table. The optimum amount of refrigerant is different between winter (temperature -8 ° C) and summer (temperature + 35 ° C). From the table, 1.568kg-1.110kg = 0.45
There is a difference of 8 kg. In addition, as shown in Table 1, CO _{2 of the} test
In the heat pump water heater, the space on the high pressure side is 9
%, And the remaining 91% is the low pressure space,
It can be said that it is negligibly small as a high-pressure space. The amount of refrigerant on the high pressure side is smaller than the amount of refrigerant on the low pressure side. Such a heat pump hot water supply system
Destructive energy such as explosion due to high pressure can also be reduced.

However, when the high-pressure space is small as described above, the distribution of the refrigerant during the heat pump operation in summer is high in the low-temperature space because the temperature is high and the evaporation temperature (low-pressure pressure) rises. Since the weight ratio of the refrigerant to be used is increased, the amount of the refrigerant on the high pressure side is correspondingly insufficient, so that the high pressure is likely to be low.

Further, since the expansion valve changes its ability to flow the refrigerant due to the differential pressure between the high pressure and the low pressure, the differential pressure also decreases in summer, and the refrigerant flow rate may be insufficient even when fully opened. In other words, it becomes impossible to automatically supply a proper amount of refrigerant to the evaporator by the expansion valve, and the evaporation temperature (low pressure) is abnormally lowered, which also causes a decrease in the coefficient of performance. In this case, the temperature of the gas sucked into the compressor and the temperature of the gas discharged from the compressor are too high, which may impair the life of the compressor or the refrigerating machine oil. Such inconvenience occurs.

On the other hand, if the closed cycle is filled with the optimum amount of the refrigerant for the summer operation, the high pressure may rise too much in the winter and the refrigeration cycle may not work. In other words, an excessive amount of refrigerant will be present on the high pressure side, and since it will be an abnormally high pressure before heat exchange, it will be shut down by a protection device set below the design pressure, or an unnecessary high pressure rise will occur. It causes a decrease in the coefficient of performance. The hot water supply load is higher in winter and the operation time is longer. Even when hot water is stored, high-temperature hot water is usually required, and high pressure tends to naturally increase, resulting in high power consumption. Considering the coefficient of performance throughout the year, it is preferable to set the refrigerant charge amount mainly in winter, and the operating efficiency (coefficient of performance COP) in summer is unavoidably reduced.

In the case of the CO ₂ heat pump water heater used as the tester, if the difference between the optimum refrigerant amount at the minimum and maximum operating temperatures is controlled as shown in Table 1 above, the target high pressure and low pressure can be obtained, and throughout the year. Stable operation is possible. In the case of a CO ₂ heat pump water heater with a small space on the high pressure side, as in the example of this test machine, generally, the same design is possible. In the case of the tester, the refrigerant filling amount is the optimum amount in summer of 1.58
6 kg (100%), the optimum amount in winter is 1.1
0.458 kg (29%), which is the difference from 10 kg (71%)
%) From the gas cooler outlet of the high pressure side space somewhere in the space between the expansion valves.

In the case of a normal CO ₂ heat pump water heater, when the temperature of the refrigerant gas at the outlet of the gas cooler is cooled to about 31 ° C. or lower at which it becomes a liquid, and when the temperature approaches the water supply temperature, the enthalpy difference between the inlet and outlet of the gas cooler increases, so the refrigerant heating capacity is increased. Also grows. If the compressor is operated at the same high pressure, the compressor power does not change, and the coefficient of performance COP becomes large, which is preferable. Liquid has the highest density of the refrigerant gas, and the higher the temperature of the discharge gas near the compressor discharge chamber, the lower the density of the refrigerant gas. Therefore, as the absorption efficiency, it is preferable to absorb the gas in the space including the gas cooler outlet that becomes liquid and reaching the expansion valve via the high pressure side of the refrigerant heat exchanger. For example, in the figure,
When the high pressure side of the refrigerant heat exchanger 3 is arranged on the outlet side of the gas cooler 2, the low pressure side of the refrigerant heat exchanger 3 can be cooled by the outlet low temperature refrigerant of the air heat exchanger which is the evaporator 5.

Evaporation temperature is usually 15 ° C even in the highest temperature in summer
Since it is below, and the operation is performed at 0 ° C. or less in winter, the refrigerant on the high pressure side has the lowest temperature at the outlet of the refrigerant heat exchanger.
Therefore, since the temperature can be sufficiently lower than 31 ° C., it is possible to efficiently and efficiently absorb it in the smallest space (receiver) as a low temperature liquid refrigerant at high pressure. In this way, if a receiver equal to the space corresponding to the difference in the amount of high-pressure side refrigerant in winter and summer is installed, it can be supplied as a low temperature liquid refrigerant to the expansion valve downstream of the receiver throughout the year. In this case, the amount of refrigerant present inside the gas cooler does not need to include the amount of refrigerant that can be absorbed by the receiver, so there is no high-pressure abnormality or an unnecessarily high high-pressure.
Stable operation can be performed throughout the year.

In the refrigeration cycle of FIG. 1 according to the present invention, a buffer 10 is provided as a receiver for absorbing the above refrigerant,
Each pipe T ₅ , T ₆ , T including the pipe T ₄ and the buffer 10
By forming a control circuit by ₇ , and opening the second buffer solenoid valve 11, the low-pressure refrigerant liquid can be recovered from the confluence portion A through the branch portion C to the buffer 10 which is the refrigerant receiver, and the high-pressure side From the point B, the high pressure refrigerant can be collected in the buffer 10 through the branch portion C.

When the first buffer solenoid valve 9 is opened, the discharge pressure of the compressor 1, which is the maximum pressure of the refrigeration cycle, is applied to the inside of the buffer 10, so that the refrigerant liquid inside the confluence A or the refrigerant expansion. It can be discharged toward point B downstream of the valve 4, and the amount of refrigerant can be controlled.

Thus, the state (pressure / pressure) of the high-pressure side gas cooler inlet / outlet on the refrigerating cycle for heating the hot water supply is the target.
Temperature) can be adjusted to be optimal,
It is possible to prevent the target high pressure from fluctuating due to the fluctuation of the low-pressure side refrigerant amount due to the seasonal (temperature) fluctuation which is the subject.

FIG. 2 relates to the second refrigerating cycle of the heat pump water heater of the present invention. In the case of FIG. 1, as described above, the merging portion downstream of the refrigerant expansion valve via the defrost electromagnetic valve 8 from the compressor discharge side. While the pipe T ₅ that branches from the middle of the pipe T ₄ that reaches A to the buffer 10 is provided, the pipe T ₅ is eliminated and the heater 17 is attached to the buffer 10.
Other than that, the configuration is the same as that of the refrigeration cycle in FIG. 1 except that it can be electrically heated.
Also in this case, the buffer 10 is provided as a receiver that absorbs the refrigerant amount, and the target high pressure or low pressure is obtained by controlling the difference in the refrigerant amounts, as in FIG. That is, in this refrigeration cycle, the buffer solenoid valve 11 can be opened as in FIG. 1 to recover the low-pressure refrigerant liquid from the merging portion A to the buffer 10 through the merging portion C of the pipes T ₆ and T ₇ , or The high-pressure refrigerant liquid can be collected in the buffer 10 from the point B on the high-pressure side through the merging portion C.

On the other hand, since the buffer 10 is provided with the heater 17, when the buffer solenoid valve 11 is opened and the heater 17 is energized and heated, the refrigerant liquid inside the buffer 10 evaporates, the internal pressure rises, and the refrigerant liquid inside becomes the point A. It can be discharged toward the pipe at point B.

Thus, as described above, in the heat pump water heater of the present invention, the target state (pressure / temperature) of the high-pressure side gas cooler inlet / outlet on the refrigerating cycle for heating the hot water is adjusted to be optimum. This makes it possible to prevent the target high pressure from fluctuating due to fluctuations in the refrigerant amount on the low pressure side due to seasonal (temperature) fluctuations,
If possible, provide efficient and stable hot water supply throughout the year.
In the above description, C using CO ₂ as the refrigerant is used.
Although an O ₂ heat pump water heater has been described, the present invention is particularly adapted to CO ₂ refrigerants with good results, but it does not preclude the use of the same global environment friendly refrigerants.

[0042]

As described above, according to the present invention, the compressor, the gas cooler, the refrigerant heat exchanger, the refrigerant expansion valve, and the evaporator are sequentially connected by the refrigerant pipe, and the accumulator is arranged on the compressor suction side.
In a heat pump water heater that circulates water to a countercurrent type gas cooler to raise the temperature, branches from the middle of the pipe from the discharge side of the compressor to the gas cooler and branches to a defrost solenoid valve, and further branches to the first buffer solenoid valve. A refrigerant control circuit is provided from the buffer point C to the point A downstream of the refrigerant expansion valve or point B upstream of the refrigerant expansion valve without passing through the buffer. One of the two buffer solenoid valves, or any solenoid valve is operated to collect the refrigerant in the refrigeration cycle in the refrigerant buffer or to fill the refrigeration cycle, or to attach a heater to the buffer and add a heater operation to freeze the refrigerant. By filling the cycle, it is possible to adjust the required amount of refrigerant, reducing the high pressure side refrigerant space to reduce the destruction energy such as explosion due to abnormal high pressure, and improve safety. With Mel, a high pressure is prevented from varying, optimal refrigerant amount adjustment for the target according to the season variation due to variations of the low-pressure refrigerant quantity seasonal (temperature) fluctuates,
The optimum hot water temperature can be realized with a simple structure, the coefficient of performance is high, the economy is extremely rich, and it has the remarkable effect of enabling efficient and stable hot water supply throughout the year.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a refrigeration cycle of a heat pump water heater according to the present invention.

FIG. 2 is a diagram showing another example of the refrigeration cycle of the heat pump water heater according to the present invention.

[Explanation of symbols]

1 compressor 2 gas cooler 3 Refrigerant heat exchanger 4 Refrigerant expansion valve 5 Evaporator (air heat exchanger) 7 Accumulator 8 defrost solenoid valve 9 First buffer solenoid valve 10 buffers 11 Second buffer solenoid valve 13 water inlet 14 Hot water outlet

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidetomo Kuromoto 4-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Electric Power Technology Laboratory (72) Inventor Masahiko Kumagai Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa No. 4-1 Electric Power Research Laboratory, TEPCO (72) Inventor Ryotaro Tateyama No. 4 Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Inside Electric Power Research Laboratory, TEPCO (56) Reference JP 10- 47799 (JP, A) JP 2001-65888 (JP, A) JP 56-146961 (JP, A) Actual Kaihei 4-61271 (JP, U) (58) Fields investigated (Int.Cl. ⁷⁾ , DB name) F25B 1/00 395 F25B 1/00 385 F24H 1/00 611 F25B 47/02 530

Claims (5)

(57) [Claims] 1. A compressor, a gas cooler, a refrigerant heat exchanger, a refrigerant expansion valve, and an evaporator are sequentially connected by a refrigerant pipe, and an accumulator is arranged on the suction side of the compressor to allow water to flow to a countercurrent gas cooler. In a heat pump water heater that raises the temperature by means of a refrigerant control circuit that branches from the middle of the pipe from the compressor discharge side to the gas cooler and reaches the refrigerant expansion valve downstream from the defrost electromagnetic valve, and further branches before the defrost electromagnetic valve.
A control circuit leading from the second buffer solenoid valve to the refrigerant control circuit merging portion downstream from the second buffer solenoid valve via the buffer solenoid valve and the refrigerant buffer, and a refrigerant control circuit extending midway from the control circuit to the refrigerant expansion valve upstream. The refrigerant of the refrigeration cycle is recovered in the refrigerant buffer by operating either or both of the first and second buffer solenoid valves, respectively, or the refrigeration cycle is filled with the refrigerant to adjust the required amount of refrigerant. A heat pump water heater characterized by that. 2. A compressor, a gas cooler, a refrigerant heat exchanger, a refrigerant expansion valve, and an evaporator are sequentially connected by a refrigerant pipe, and an accumulator is arranged on the suction side of the compressor to let water flow to a countercurrent gas cooler. In the heat pump water heater that raises the temperature by means of a refrigerant control circuit that branches from the middle of the pipe from the compressor discharge side to the gas cooler and reaches the refrigerant expansion valve downstream from the defrost electromagnetic valve, and a buffer electromagnetic valve from the refrigerant buffer equipped with a heater. By providing a control circuit to the refrigerant control circuit merging portion downstream of the refrigerant expansion valve and a refrigerant control circuit from the middle of the control circuit to the refrigerant expansion valve upstream, respectively, by operating the buffer solenoid valve of the control circuit Refrigerant cycle refrigerant should be collected in the refrigerant buffer or a heater operation should be performed to fill the refrigeration cycle and adjust the required amount of refrigerant. Heat pump water heater, characterized. 3. The heat pump according to claim 1, wherein an accumulator is arranged on the suction side of the compressor, and the high pressure side of the refrigerant heat exchanger is installed at the gas cooler outlet and the low pressure side is located between the air heat exchanger and the accumulator. Water heater. 4. The heat pump water heater according to claim 1, wherein the countercurrent gas cooler is a heat exchanger such as a double pipe system in which the amount of high pressure side refrigerant is small. 5. The heat pump water heater according to claim 1, 2, 3 or 4, wherein the hot water temperature is adjusted by adjusting the flow rate of the hot water.