WO2018163345A1

WO2018163345A1 - Heat pump hot water supply device

Info

Publication number: WO2018163345A1
Application number: PCT/JP2017/009418
Authority: WO
Inventors: 徹小出
Original assignee: 三菱電機株式会社
Priority date: 2017-03-09
Filing date: 2017-03-09
Publication date: 2018-09-13
Also published as: EP3594587A4; JPWO2018163345A1; EP3594587B1; JP6704505B2; EP3594587A1

Abstract

The present invention ensures the reliability of a compressor by reducing the maximum pressure by way of storing refrigerant in a refrigerant quantity regulator serving as a high-pressure suppressor when high temperature water is injected and by avoiding liquid compression by way of storing liquid backflow during overflow in the refrigerant quantity regulator. The degree that an expansion valve is opened is adjusted so that the difference between the indicated hot water discharge temperature and the inlet refrigerant temperature during boiling is a preset temperature differential, and when a fluid sent from the hot water tank to a condenser is at a high temperature, high pressure is suppressed by reducing the high-pressure side refrigerant density by way of changing the temperature differential and adjusting, to the opening direction, the degree that the expansion valve is opened. Meanwhile, because the low-pressure side refrigerant density increases, excess liquid refrigerant is stored in the refrigerant quantity regulator. In addition, after operation is stopped and restarted immediately after liquid refrigerant is stored in the evaporator, there is a risk of liquid compression occurring by liquid backflowing into the compressor if there is no refrigerant quantity regulator. Thus, liquid compression is avoided by storing refrigerant in the refrigerant quantity regulator and compressor reliability is ensured.

Description

Heat pump water heater

This invention relates to a heat pump water heater equipped with a refrigerant amount regulator.

Conventionally, in a heat pump cycle equipped with a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant quantity regulator, a technique for achieving a predetermined capacity with optimum efficiency by changing the amount of liquid refrigerant stored in the refrigerant quantity regulator. Has been proposed (for example, Patent Document 1). The capacity of the heat pump cycle is controlled by changing the amount of refrigerant in the condenser and adjusting the pressure on the high pressure side. The amount of refrigerant in the condenser is increased by temporarily reducing the opening of the expansion valve. Along with this, the amount of liquid refrigerant stored in the refrigerant quantity regulator at the evaporator outlet decreases. As the amount of refrigerant on the high pressure side increases, the pressure increases and the capacity increases. On the other hand, by opening the expansion valve, the amount of liquid refrigerant stored in the refrigerant amount regulator at the evaporator outlet increases, and the amount of refrigerant on the high-pressure side decreases. The capacity is reduced by reducing the pressure on the high pressure side. As described above, it is possible to operate with optimum efficiency by adjusting the amount of liquid refrigerant stored in the refrigerant quantity regulator as a cycle.

Further, conventionally, in a heat pump cycle provided with a compressor, a condenser, an expansion valve, an evaporator, and an internal heat exchanger without using a refrigerant quantity regulator, cost is suppressed by not providing a refrigerant quantity regulator. In addition, a technique for suppressing an increase in the high-pressure side pressure at the time of high-temperature water entry using an internal heat exchanger has been proposed (for example, Patent Document 2). When the fluid sent to the condenser by the hot water circulation pump from the bottom of the hot water tank is at a high temperature (that is, at the time of high-temperature water entry), the density of the refrigerant existing in the condenser decreases and the pressure increases abnormally. In order to suppress this, the refrigerant from the condenser outlet to the expansion valve inlet is cooled, thereby increasing the refrigerant density on the high-pressure side and suppressing an abnormal increase in the high-pressure side pressure. The refrigerant from the condenser outlet to the expansion valve inlet is cooled by the refrigerant from the evaporator outlet to the compressor. As described above, cost reduction can be achieved by suppressing the pressure on the high pressure side with the internal heat exchanger without using the refrigerant amount regulator.

Japanese Patent Publication No. 7-18602 JP 2005-164103 A

In Patent Document 1, the efficiency is improved by adjusting the refrigerant amount and pressure on the high-pressure side using a refrigerant quantity regulator. However, in order to store the liquid refrigerant, a refrigerant volume regulator having a large volume is necessary, and there is a problem that the equipment becomes large and the cost increases. In Patent Document 2, since the refrigerant quantity regulator is not used, an increase in the size of the apparatus can be avoided, but an internal heat exchanger is used in place of the refrigerant quantity regulator as means for suppressing an increase in the high-pressure side pressure during high-temperature water entry. . In this case, there are the following problems. Immediately after the operation of the apparatus is stopped, the refrigerant flows into the evaporator having a small heat capacity and accumulates as a liquid refrigerant. After a certain period of time, liquid refrigerant accumulates in the compressor having a large heat capacity.However, when the apparatus is restarted immediately after the liquid refrigerant is accumulated in the evaporator, there is no refrigerant amount regulator, so the refrigerant is liquid in the compressor. There is a risk of backing. If the compressor liquid-compresses the liquid-backed refrigerant, it may lead to failure.

This invention has been made to solve the above-mentioned problems, and while suppressing the increase in size and cost of the equipment, it reduces the high pressure at the time of high-temperature incoming water and avoids liquid compression due to liquid back during transition. It aims at providing the heat pump hot-water supply apparatus which can ensure the reliability of an apparatus.

A heat pump hot water supply apparatus according to the present invention includes a refrigerant circuit formed by annularly connecting a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant amount regulator, and a hot water tank for storing hot water heated by the condenser A hot water circulation pump that circulates hot water between the condenser and the hot water tank, an inlet refrigerant temperature detector that detects an inlet refrigerant temperature of the condenser, and an inlet that detects an inlet water temperature of the condenser The valve opening of the expansion valve is set so that the difference between the temperature of the hot water supplied from the water temperature detector and the tank controller provided in the hot water tank and the inlet refrigerant temperature is a preset temperature difference. A heat source device control unit that adjusts, and the heat source device control unit adjusts the valve opening of the expansion valve in the opening direction by changing the temperature difference when the inlet water temperature becomes equal to or higher than a threshold value. It is characterized by that.

The heat pump hot water supply apparatus according to the present invention adjusts the opening degree of the expansion valve in the opening direction when the fluid sent from the hot water tank to the condenser by the hot water circulation pump is at a high temperature (that is, at high temperature water entry), The refrigerant density on the high-pressure side is reduced to suppress the high pressure so as not to exceed a certain pressure. On the other hand, since the refrigerant density on the low pressure side increases, the liquid is stored in the refrigerant quantity regulator as an excess liquid refrigerant. Even when the apparatus is restarted immediately after the liquid refrigerant is stored in the evaporator, the refrigerant backed from the evaporator can be stored as the liquid refrigerant in the refrigerant amount regulator. With this configuration, it is possible to avoid liquid compression by storing in the refrigerant amount regulator and to ensure the reliability of the compressor. Furthermore, if a suction muffler having a space capable of storing liquid refrigerant is used as the refrigerant amount regulator, it is possible to suppress the increase in size and cost of the device.

Further, the heat pump hot water supply apparatus according to the present invention includes a hot water instruction temperature from a tank control unit provided in a hot water tank and a temperature detected by an inlet refrigerant detection unit of the condenser (hereinafter referred to as an inlet refrigerant temperature). The valve opening degree of the expansion valve is controlled so that the difference becomes a preset temperature difference (hereinafter referred to as a set temperature difference). Although it is possible to control the opening of the expansion valve using only the detected temperature obtained by the water inlet detector of the condenser and the target value of the condenser inlet refrigerant detector, depending on the environmental conditions of operation There is a possibility that hot water does not boil because temperature> target value. On the other hand, according to the present invention, the temperature difference is set in advance so that the inlet refrigerant temperature−the temperature of the hot water instruction> 0, and the opening of the expansion valve is adjusted so as to be the temperature difference. The water can be boiled reliably.

It is a circuit diagram of the heat pump hot-water supply apparatus of this invention. It is a block diagram of a heat source machine control part and a storage part. It is sectional drawing of a compressor and a refrigerant | coolant amount regulator. It is a flowchart of the boiling operation control of a heat source machine control part. It is a schematic diagram which shows the hot water storage temperature transition in a hot water tank. It is a time chart of the inlet water temperature of the condenser, the inlet refrigerant temperature, the amount of refrigerant stored in the refrigerant amount regulator, the hot water instruction temperature of the tank controller, and the valve opening degree of the expansion valve. It is a circuit diagram of the heat pump hot-water supply apparatus of this invention provided with an internal heat exchanger. It is a pressure-enthalpy diagram showing the effect at the time of high pressure suppression. FIG. 6 is a pressure-enthalpy diagram showing the effect of improving the coefficient of performance (Coefficent of Performance; hereinafter referred to as COP).

Embodiment 1 FIG.
Hereinafter, an outdoor unit 100 of an air conditioner according to Embodiment 1 of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a heat pump water heater 100 according to an embodiment of the present invention. The heat pump hot water supply apparatus 100 includes a heat source unit 200 and a tank unit 300.

The heat source unit 200 includes a compressor 1 that compresses and discharges a refrigerant, a condenser 2 that exchanges heat between the refrigerant and water, an electronically controlled expansion valve 3 that depressurizes a high-pressure refrigerant to a low pressure with variable opening, and air And an evaporator 4 for exchanging heat between the refrigerant and the refrigerant, and a refrigerant circuit formed by annularly connecting a refrigerant amount regulator 6 capable of temporarily storing liquid refrigerant by a refrigerant pipe 19. The heat source unit 200 includes an inlet water temperature detection unit 9 that detects the inlet water temperature of the condenser 2, an outlet water temperature detection unit 10 that detects the outlet water temperature of the condenser 2, and the outside air that detects the outside air temperature. A temperature detector 16, an inlet refrigerant temperature detector 17 that detects the inlet refrigerant temperature of the condenser 2, and an outlet refrigerant temperature detector 18 that detects the outlet refrigerant temperature of the evaporator 4 are provided. Each of these detection units can be constituted by a temperature sensor. A fan 8 is installed near the evaporator 4 for promoting heat exchange between the refrigerant in the evaporator 4 and air. The fan 8 is rotated by driving the fan motor 7, and an air flow passing through the evaporator 4 is generated by the rotation. Carbon dioxide (CO ₂ ) can be used as the refrigerant. The operation of the heat source unit 200 is controlled by the heat source unit control unit 13.

The tank unit 300 includes a hot water tank 14 that stores hot water heated by the condenser 2, and a hot water circulation pump 11 that is disposed between the condenser 2 and the hot water tank 14 and circulates the hot water therebetween. . The condenser 2 and the hot water tank 14 are connected to each other by a hot water circulation pipe 15. The operation of the tank unit 300 is controlled by the tank control unit 12. The tank control unit 12 can transmit a tapping instruction temperature to the heat source unit control unit of the heat source unit 200.

FIG. 2 is a block diagram of the heat source machine control unit 13. The heat source machine control unit 13 sets the rotation speed of the compressor rotation speed control section 21 that controls the rotation speed of the compressor 1, the fan rotation speed control section 22 that controls the rotation speed of the fan motor 7, and the rotation speed of the hot water circulation pump 11. A pump speed controller 23 for controlling, a detection temperature receiver 24 for receiving a detected temperature such as an inlet refrigerant temperature of the condenser 2, an expansion valve opening adjusting unit 25 for adjusting the opening of the expansion valve 3, and a tank And a hot water command temperature receiving unit 26 that receives the hot water command temperature emitted from the control unit 12. The expansion valve opening degree adjusting unit 25 adjusts the valve opening degree of the expansion valve 3 so that the difference between the tapping instruction temperature and the inlet refrigerant temperature becomes a set temperature difference. The expansion valve opening degree adjusting unit 25 changes the set temperature difference and adjusts the valve opening degree of the expansion valve 3 in the opening direction when the inlet water temperature becomes equal to or higher than a predetermined threshold value. The set temperature difference is stored in advance in the storage unit 30 in the heat source unit 200. The heat source machine control unit 13 is configured by, for example, a microchip. The storage unit 30 is configured by a semiconductor memory, for example.

FIG. 3 is a cross-sectional view of the compressor 1 and the refrigerant amount regulator 6. When the refrigerant in the gas-liquid two-phase state flows from the evaporator 4 into the refrigerant amount adjuster 6 through the suction pipe 31, the gas refrigerant flows into the compressor 1 through the relay pipe 32, and the liquid refrigerant is surplus. The refrigerant is stored in the liquid refrigerant storage section 33 of the refrigerant amount regulator 6. The compressor 1 compresses the gaseous refrigerant, discharges it from the discharge pipe 34, and sends it to the condenser 2. The liquid refrigerant reservoir 33 is an internal space provided at the bottom of the cylindrical refrigerant quantity regulator 6. A so-called suction muffler that provides a silencing effect can be used as the refrigerant amount adjuster 6. In this case, the suction muffler serves as both a muffler and a surplus refrigerant reservoir. Refrigerating machine oil flows into the refrigerant amount adjuster 6 from the suction pipe 31 together with the refrigerant. The relay pipe 32 is provided with an oil return hole 35 for returning the refrigeration oil accumulated at the bottom of the liquid refrigerant reservoir 33 to the compressor 1. In the bottom of the liquid refrigerant storage part 33, the refrigerant and the refrigerating machine oil may be mixed or separated and temporarily stored.

FIG. 4 is a flowchart of the boiling operation control by the heat source machine control unit 13. Hereinafter, the boiling operation control of the heat pump water heater 100 will be described with reference to FIG.

First, the heat source device control unit 13 provided in the heat source device unit 200 starts the boiling operation when receiving a boiling operation instruction from the tank control unit 12 provided in the tank unit 300 (step S11). The heat source machine control unit 13 receives the hot water instruction temperature together with the boiling operation instruction. Next, the heat source device control unit 13 receives the inlet water temperature of the condenser 2 (step S12). When the inlet water temperature is equal to or higher than the predetermined temperature, the heat source machine control unit 13 ends the operation control without performing the boiling operation (step S13). When the inlet water temperature is lower than the predetermined temperature, the heat source machine controller 13 controls the rotation frequency of the compressor 1 based on the inlet water temperature detected by the outside air temperature detector 16 and the inlet water temperature detector 9 ( Step S14).

Next, the heat source machine control unit 13 determines whether or not the inlet water temperature detected by the inlet water temperature detection unit 9 of the condenser 2 is equal to or higher than a predetermined threshold (step S15). When the inlet water temperature is less than the predetermined threshold, the heat source machine control unit 13 reads the first temperature difference stored in the storage unit 30 and sets this as the set temperature difference (step S16). When the inlet water temperature is equal to or higher than the predetermined threshold, the heat source machine control unit 13 reads the second temperature difference stored in the storage unit 30 and sets this as the set temperature difference (step S17). The second temperature difference is smaller than the first temperature difference.

The heat source machine control unit 13 performs the following processing after setting the temperature difference. First, the heat source device controller 13 receives the inlet refrigerant temperature detected by the inlet refrigerant detector 17 of the condenser 2 (step S18). Next, the heat source machine control unit 13 calculates the difference between the tapping temperature and the inlet refrigerant temperature (step S19). Hereinafter, the difference is referred to as a calculated temperature difference. Next, the heat source machine control unit 13 adjusts the opening degree of the expansion valve 3 so that the calculated temperature difference becomes the set temperature difference (step S20). When the inlet water temperature of the condenser 2 exceeds a predetermined threshold, the valve opening is adjusted in the opening direction as a result of adjusting the valve opening in accordance with a second temperature difference smaller than the first temperature difference. The

The first temperature difference should be set to be the optimum COP under environmental conditions, for example, certain outside air temperature conditions, incoming water temperature conditions (winter standard heating conditions, intermediate standard heating conditions, etc. defined by JIS). Can do. The second temperature difference is set to a value smaller than the first temperature difference so that the high-pressure side pressure at the time of high-temperature water entry does not exceed the designed upper limit value. These temperature differences are constant values under certain conditions such as the outside air temperature and the incoming water temperature, and can be constant values within a range of 15 to 30 ° C., for example. The opening degree of the expansion valve 3 is the target value of the outside air temperature, the inlet water temperature detected by the inlet water temperature detector 9 of the condenser 2, and the inlet refrigerant temperature detected by the inlet refrigerant detector 17 of the condenser 2. And it is controllable only with the hot water instruction temperature from the tank controller 12. However, depending on the environmental conditions, there is a relationship of the hot water instruction temperature> the target value of the inlet refrigerant temperature, and the hot water may not boil. For example, in the case of performing a process of uniformly reducing the target value of the inlet refrigerant temperature regardless of the hot water instruction temperature in order to suppress the high-pressure side pressure during high temperature water injection, the relationship between the hot water instruction temperature> the target value of the inlet refrigerant temperature Can be. On the other hand, in the heat pump hot water supply apparatus 100 of the present embodiment, a temperature difference that satisfies the inlet refrigerant temperature−the hot water instruction temperature> 0 is stored in advance in the storage unit 30 as the first and second temperature differences. When the inlet water temperature is less than the predetermined threshold, the first temperature difference is set as the set temperature difference, and when the inlet water temperature is equal to or higher than the predetermined threshold, the second temperature difference smaller than the first temperature difference is set as the set temperature difference. Then, the opening degree of the expansion valve 3 is adjusted so that the calculated temperature difference becomes the set temperature difference. By such treatment, it is possible to avoid the problem that hot water does not boil while adjusting the high-pressure side pressure so as not to exceed the designed upper limit pressure at the time of high-temperature water entry.

FIG. 5 is a schematic diagram showing the temperature transition of hot water in the hot water tank 14. Although the temperature of water supplied to the heat source unit 200 is low (for example, 5 ° C.) from the start of boiling to the time of boiling operation, the inlet water temperature of the condenser 2 increases (for example, 5 to 5) before the completion of boiling. 60 ° C.). For example, when the city water minimum temperature is 5 ° C. and the hot water maximum temperature is 90 ° C., the temperature of the water in the hot water tank 14 before the boiling operation is about 5 ° C., and the temperature of the hot water in the hot water tank 14 during the boiling operation is The upper side is 90 ° C and the lower side is 5 ° C. The temperature of the hot water in the hot water tank 14 before completion of boiling is 90 ° C. on the upper side and medium temperature water, for example, 60 ° C. on the lower side.

When the inlet water temperature rises, the density of the refrigerant present in the condenser 2 decreases. At this time, the pressure rises abnormally with the first temperature difference set in advance so that the optimum COP is obtained under certain environmental conditions. Therefore, the environmental conditions where the pressure on the high pressure side may exceed the design pressure (for example, under the low outside air conditions, the maximum boiling temperature and the maximum heating capacity are required, the high inlet refrigerant temperature of the condenser 2 and the compressor Under the condition of reaching a maximum rotational speed of 1, a second temperature difference smaller than the first temperature difference is set as a set temperature difference. Since the second temperature difference is smaller than the first temperature difference, the set temperature difference becomes small when the inlet water temperature becomes equal to or higher than the predetermined temperature. And the opening degree of the expansion valve 3 is adjusted so that the difference between the tapping temperature from the tank controller 12 and the detected temperature obtained by the inlet refrigerant detector 17 of the condenser 2 becomes the set temperature difference after the change. adjust. By such control, the refrigerant density on the high pressure side can be reduced, and the high pressure can be suppressed so that the pressure on the high pressure side does not exceed the design pressure.

FIG. 6 shows an inlet water temperature 41 of the condenser 2, an inlet refrigerant temperature 42 of the condenser 2, a tapping instruction temperature 43 of the tank controller 12, a stored refrigerant quantity 44 of the refrigerant quantity regulator 6, and a valve opening of the expansion valve. It is a time chart which shows. By adjusting the opening degree of the expansion valve 3, the pressure on the high pressure side is suppressed, while the refrigerant density on the low pressure side increases. Until the time T1 when the inlet water temperature 41 detected by the inlet water temperature detection unit 9 of the condenser 2 reaches a predetermined threshold value 41 (for example, 50 ° C.), the refrigerant is used up below the design pressure, so that excess liquid refrigerant is not generated. Therefore, the liquid refrigerant is not stored in the refrigerant quantity regulator 6. During this time, the inlet refrigerant temperature 42 and the tapping hot water instruction temperature 43 are also constant. After the inlet water temperature 41 detected by the inlet water temperature detector 9 of the condenser 2 exceeds the predetermined threshold value 41a, the excess liquid refrigerant is stored in the refrigerant amount regulator 6 in order to operate at a design pressure or lower. And suppress high pressure. That is, the valve opening adjustment in steps S17 to S20 is started from time T1 when the inlet water temperature exceeds the predetermined threshold value 41. At this time, the valve opening degree 45 is adjusted so that the difference between the inlet refrigerant temperature 42 and the hot water instruction temperature 43 is the same as a certain set temperature difference (second temperature difference). The valve opening 45 increases from time T1. This reduces the actual temperature difference. For example, the temperature difference between the inlet refrigerant temperature 42 and the tapping temperature 43 until the time point T1 when the inlet water temperature 41 reaches the predetermined threshold value 41a is 30 ° C., and after the time point T1 when the inlet water temperature 41 reaches the predetermined threshold value 41a. The temperature difference is 25 ° C. The boiling operation is terminated at time T2 when the inlet water temperature 41 reaches the predetermined temperature 41b (step S13). The refrigerant filling amount of the entire refrigeration circuit can be about 1000 g, for example. The target value 44a of the liquid refrigerant storage amount 44 in the refrigerant amount adjuster 6 can be set to about 30 g, for example. When a suction muffler is used as the refrigerant quantity regulator 6, excess liquid refrigerant is stored at the bottom of the suction muffler.

The heat source machine control unit 13 may start the boiling operation soon after the boiling operation is stopped. After the operation is stopped, the expansion valve 3 is fully opened, and the pressures on the high pressure side and the low pressure side are balanced. At this time, the refrigerant is drawn to the outside air temperature, flows into the evaporator 4 having a small heat capacity (easy to radiate heat), and is stored as a liquid refrigerant. After a certain period of time, the liquid refrigerant is stored in the compressor 1 having a large heat capacity. However, when restarted immediately after the liquid refrigerant has been stored in the evaporator 4, the liquid refrigerant stored in the evaporator 4 flows into the compressor 1 at once. . Unlike the present embodiment, when there is no refrigerant amount adjuster 6, the liquid refrigerant may be liquid-backed to the compressor 1 and the compressor 1 may be liquid-compressed. On the other hand, according to the heat pump hot water supply apparatus 100 of the present embodiment, the liquid refrigerant from the evaporator 4 at the time of starting the apparatus is temporarily stored in the refrigerant amount regulator 6, so that the refrigerant liquid by the compressor 1 is stored. Compression can be prevented and the reliability of the compressor 1 can be ensured.

As described above, in the heat pump hot water supply apparatus 100 of the present embodiment, when the fluid sent from the bottom of the hot water tank 14 to the condenser 2 by the hot water circulation pump 11 is high temperature (that is, at high temperature water entry), the expansion valve 3. The refrigerant density on the high pressure side is decreased by adjusting the valve opening degree of the valve in the opening direction, and the high pressure is suppressed so as not to exceed a certain pressure. On the other hand, since the refrigerant density on the low pressure side increases, the excess liquid refrigerant is stored in the refrigerant amount regulator 6. Since the surplus liquid refrigerant is stored in the refrigerant amount regulator 6, it is not necessary to provide an internal heat exchanger for exchanging heat between the high-pressure side refrigerant and the low-pressure side refrigerant, and the cost can be reduced. After the operation is stopped, the refrigerant flows into the evaporator 4 having a small heat capacity and is stored as a liquid refrigerant. Thereafter, when a certain time has elapsed, the liquid refrigerant is stored in the compressor 1 having a large heat capacity. However, when the apparatus is restarted immediately after the liquid refrigerant is stored in the evaporator 4, the compression is performed when the refrigerant amount regulator 6 is not provided. There is a risk of liquid back into the machine 1 and liquid compression. Therefore, the heat pump hot water supply apparatus 100 of the present embodiment is provided with the refrigerant amount adjuster 6, and by storing the liquid refrigerant in this, the liquid compression of the compressor 1 can be avoided and the reliability of the compressor 1 can be ensured. It becomes possible. A suction muffler can be used as the refrigerant amount regulator 6. By combining the suction muffler with the silencer and the refrigerant amount adjuster 6, it is not necessary to provide another refrigerant amount adjuster, and the effects of cost reduction and volume increase suppression of the outdoor unit are obtained.

Embodiment 2. FIG.
Hereinafter, an outdoor unit 100 for an air conditioner according to Embodiment 2 of the present invention will be described with reference to the drawings.

FIG. 7 is a circuit diagram of the heat pump hot water supply apparatus 100 including the internal heat exchanger 5. For example, the refrigerant quantity regulator 6 having a certain size or more may not be installed due to structural restrictions. In such a case, when there is a possibility that the design pressure on the high pressure side may be exceeded, as shown in FIG. 7, the refrigerant from the outlet of the condenser 2 to the inlet of the expansion valve 3 and the outlet of the evaporator 4 to the compressor 1 It is possible to provide an internal heat exchanger 5 that exchanges heat with the refrigerant up to the inlet. In this case, the expansion valve 3 is provided on the refrigerant flow path between the evaporator 4 and the internal heat exchanger 5.

FIG. 8 is a pressure-enthalpy diagram showing the effect of suppressing high pressure. FIG. 9 is a pressure-enthalpy diagram showing the effect when COP is improved. The internal heat exchanger 5 has two roles. One role is to increase the refrigerant density of the evaporator 4 when the inlet water temperature of the condenser 2 rises due to heat exchange by the internal heat exchanger 5, as shown in FIG. Accumulate. Accordingly, the refrigerant density on the high pressure side can be reduced to suppress high pressure.

Reference numerals

51 and 52 indicate enthalpy ranges on the low-pressure side and the high-pressure side that vary due to heat exchange by the internal heat exchanger 5. Another role is to apply superheat at the outlet of the evaporator 4 as shown in FIG. 9 and improve COP. Reference numeral 54 in FIG. 9 indicates an enthalpy range that increases when superheat is applied to the outlet of the evaporator 4 by the internal heat exchanger 5. Reference numeral 55 is a refrigerant state transition when the internal heat exchanger 5 is present, and reference numeral 56 is a refrigerant state transition when the internal heat exchanger 5 is not present.

When the internal heat exchanger 5 and the refrigerant amount regulator 6 are used in combination as in the present embodiment, the above-described effects of high pressure suppression and COP improvement are obtained. If the amount of liquid stored in the refrigerant amount controller 6 can be increased to an extent that does not overflow, the internal heat exchanger 5 can be made compact, leading to cost reduction. Moreover, if it controls so that only the refrigerant | coolant amount regulator 6 can store the whole quantity of an excess liquid refrigerant | coolant, the internal heat exchanger 5 can be deleted like Embodiment 1, and the further cost reduction will also be attained. .

DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Expansion valve 4 Evaporator 5 Internal heat exchanger 6 Refrigerant amount regulator 7 Fan motor 8 Fan 9 Inlet water temperature detection part 10 Outlet water temperature detection part 11 Hot water circulation pump 12 Tank control part 13 Heat source machine Control unit 14 Hot water tank 15 Hot water circulation pipe 16 Outside air temperature detection unit 17 Inlet refrigerant temperature detection unit 18 Outlet refrigerant temperature detection unit 19 Refrigerant pipe 21 Compressor rotation speed control unit 22 Fan rotation speed control unit 23 Pump rotation speed control unit 24 Detection Temperature receiving section 25 Expansion valve opening adjusting section 26 Temperature instruction receiving section 30 Storage section 31 Suction pipe 32 Relay pipe 33 Liquid refrigerant storage section 34 Discharge pipe 35 Oil return hole 100 Heat pump hot water supply apparatus 200 Heat source unit 300 Tank unit

Claims

A refrigerant circuit formed by annularly connecting a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant amount regulator, a hot water tank for storing hot water heated by the condenser, the condenser and the hot water tank A hot water circulation pump for circulating hot water between, an inlet refrigerant temperature detector for detecting an inlet refrigerant temperature of the condenser, an inlet water temperature detector for detecting an inlet water temperature of the condenser, and the hot water tank A heat source machine controller that adjusts the valve opening of the expansion valve so that the difference between the hot water discharge instruction temperature generated from the tank controller provided in the tank and the inlet refrigerant temperature becomes a preset temperature difference, and In addition, the heat source machine control unit is configured to adjust the valve opening degree of the expansion valve in the opening direction by changing the temperature difference when the inlet water temperature is equal to or higher than a threshold value.
The heat pump hot water supply apparatus according to claim 1, wherein the refrigerant amount regulator stores refrigerant when the inlet water temperature becomes equal to or higher than a threshold value.
The heat pump hot water supply apparatus according to claim 1 or 2, wherein the refrigerant amount regulator is provided at an inlet of the compressor.
The heat pump water heater according to any one of claims 1 to 3, wherein the refrigerant amount regulator is a suction muffler having a space capable of storing liquid refrigerant.
An internal heat exchanger is provided that exchanges heat between the refrigerant from the outlet of the condenser to the inlet of the expansion valve and the refrigerant from the outlet of the evaporator to the inlet of the compressor. The heat pump hot water supply apparatus according to any one of 4.
A storage unit for storing the preset temperature difference;
The heat pump hot-water supply apparatus according to any one of claims 1 to 5, wherein the preset temperature difference is a temperature difference that satisfies an inlet refrigerant temperature-a hot water instruction temperature> 0.