JP7038277B2 - Refrigeration cycle device and liquid heating device equipped with it - Google Patents

Description

The present invention relates to a refrigeration cycle device and a liquid heating device including the refrigeration cycle device.

Conventionally, as this kind of refrigeration cycle device, a two-stage compressor is provided, a part of the refrigerant is expanded from the downstream side of the heat exchanger on the user side, and the intermediate refrigerant is bypassed during the compression of the two-stage compressor. A refrigeration cycle apparatus is disclosed (see, for example, Patent Document 1).

FIG. 4 shows a conventional refrigeration cycle apparatus described in Patent Document 1.

As shown in FIG. 4, the refrigerating cycle device 100 includes a refrigerant circuit 110 for circulating a refrigerant and a rear-stage side injection pipe 120. In the refrigerant circuit 110, a compression mechanism 211 having a plurality of compression rotation elements connected in series, a heat source side heat exchanger 112, expansion mechanisms 113a and 113b, and a user side heat exchanger 114 are connected in a ring shape by piping. It is composed of a switching mechanism 115 for switching between a heating operation and a cooling operation.

Further, it is provided in the intermediate refrigerant pipe 116 for sucking the refrigerant discharged from the compression rotation element on the front stage side into the compression rotation element on the rear stage side, and is discharged from the compression rotation element on the front stage side to the compression rotation element on the rear stage side. An intermediate cooler 117 that functions as a cooler for the sucked refrigerant and an intermediate cooler bypass pipe 130 that is connected to the intermediate refrigerant pipe 116 so as to bypass the intermediate cooler 117 are provided.

The rear injection tube 120 is branched from the refrigerant circuit 110 between the heat source side heat exchanger 112 and the utilization side heat exchanger 114, and the branched refrigerant is communicated so as to return to the compression rotation element on the rear side of the compression mechanism 211. ing. Further, the injection pipe 120 is provided with a rear-stage injection valve 121 capable of controlling the opening degree.

Further, the refrigerating cycle device 100 defrosts the heat source side heat exchanger 112 by switching the switching mechanism 115 to the cooling operation state. When performing the reverse cycle defrosting operation, the heat source side heat exchanger 112 and the intercooler After flowing the refrigerant through the 117 and the injection pipe 120 on the rear stage side and detecting that the defrosting of the intercooler 117 is completed, the intermediate cooler bypass pipe 130 is used to prevent the refrigerant from flowing into the intercooler 117. At the same time, the opening degree of the injection valve 121 on the rear stage side is controlled to be large.

Japanese Unexamined Patent Publication No. 2009-133581

However, in the conventional refrigeration cycle apparatus, although the deterioration of the performance of the equipment due to the defrosting ability can be suppressed, the operation control at the start of the heating operation after the defrosting operation of the heat source side heat exchanger is not disclosed at all. do not have.

The present invention solves the above-mentioned conventional problems, and also during the heating operation of the user-side heat exchanger after the completion of the defrosting operation of the heat source-side heat exchanger, and during the heating operation of the user-side heat exchanger. It is an object of the present invention to provide a refrigerating cycle apparatus capable of suppressing a decrease in the heating capacity of the above and a liquid heating apparatus provided with the refrigerating cycle apparatus.

In order to solve the above-mentioned conventional problems, the refrigeration cycle apparatus of the present invention has a compression mechanism composed of a compression rotation element and a utilization side heat exchanger that heats a utilization side heat medium with a refrigerant discharged from the compression rotation element. From the main refrigerant circuit formed by sequentially connecting the intermediate heat exchanger, the first expansion device, and the heat source side heat exchanger with pipes, and from the pipe between the user side heat exchanger and the first expansion device. Controlled with a bypass refrigerant circuit that is branched, decompressed by the second expansion device, then heat exchanged with the refrigerant flowing through the main refrigerant circuit in the intermediate heat exchanger, and merged with the refrigerant in the middle of compression of the compression rotating element. A heating operation mode in which the user-side heat exchanger heats the user-side heat medium with the refrigerant discharged from the compression rotation element, and the heat source is provided with the refrigerant discharged from the compression rotation element. In the defrosting operation mode for defrosting the side heat exchanger and the heating operation mode which is executed after the execution of the defrosting operation mode is completed, at least for a predetermined period from the start of the execution of the heating operation mode. At each predetermined opening degree in which the flow rate of the refrigerant flowing through the first expansion device is smaller than the flow rate of the refrigerant flowing through the second expansion device, the control device determines the opening degree of the first expansion device and the opening degree of the second expansion device. It is characterized in that the opening degree is set.

As a result, the amount of decompression by the first expansion means in the main refrigerant circuit can be reduced by reducing the flow rate of the refrigerant flowing through the first expansion means and increasing the flow rate of the refrigerant flowing through the second expansion means. It is possible to suppress a decrease in the pressure of the refrigerant flowing through the heat exchanger on the heat source side, and increase the pressure of the refrigerant in the bypass refrigerant circuit that joins the refrigerant in the middle of compression of the compression rotation element to join the refrigerant in the middle of compression of the compression rotation element. Since the density of the refrigerant to be used can be increased, it is possible to sufficiently secure the flow rate of the refrigerant flowing through the heat exchanger on the user side.

According to the present invention, it is possible to suppress a decrease in the heating capacity of the user-side heat exchanger during the heating operation even during the heating operation of the user-side heat exchanger after the execution of the defrosting operation of the heat source-side heat exchanger is completed. A refrigerating cycle device and a liquid heating device including the refrigerating cycle device can be provided.

Configuration diagram of the liquid heating device according to the first embodiment of the present invention. Moriel diagram when the heating operation mode is executed after the defrosting operation mode of the refrigeration cycle device is executed. Flow chart of heating operation mode execution control after defrosting operation mode execution of the refrigeration cycle device Configuration diagram of conventional refrigeration cycle equipment

The first invention is a compression mechanism composed of a compression rotation element, a utilization side heat exchanger that heats a utilization side heat medium by a refrigerant discharged from the compression rotation element, an intermediate heat exchanger, a first expansion device, and a heat source. After branching from the main refrigerant circuit formed by sequentially connecting the side heat exchangers with pipes and the pipes between the user side heat exchanger and the first expansion device, the pressure is reduced by the second expansion device. The intermediate heat exchanger comprises a bypass refrigerant circuit that exchanges heat with the refrigerant flowing through the main refrigerant circuit and joins the refrigerant in the process of being compressed in the compression rotating element, and a control device, and discharges from the compression rotating element. A heating operation mode in which the user-side heat exchanger is heated by the used refrigerant, and a defrosting operation in which the heat source-side heat exchanger is defrosted by the refrigerant discharged from the compression rotating element. In the heating operation mode, which has a mode and is executed after the execution of the defrosting operation mode is completed, the flow rate of the refrigerant flowing through the first expansion device is the same for at least a predetermined period from the start of the execution of the heating operation mode. The control device is characterized in that the opening degree of the first expansion device and the opening degree of the second expansion device are set at each predetermined opening degree smaller than the flow rate of the refrigerant flowing through the second expansion device. It is a refrigeration cycle device.

As a result, by reducing the flow rate of the refrigerant flowing through the first expansion means, the flow rate of the refrigerant in the evaporator decreases, the enthalpy of the refrigerant at the outlet of the evaporator increases, and if an accumulator is provided, the accumulator The vaporization of the refrigerant staying in the water is promoted.

Further, by increasing the amount of the refrigerant flowing through the second expansion means, the amount of decompression by the first expansion means in the main refrigerant circuit can be reduced, so that the pressure drop of the refrigerant flowing through the heat source side heat exchanger can be suppressed. , The pressure of the refrigerant in the bypass refrigerant circuit that joins the refrigerant in the middle of compression of the compression rotation element can be increased to increase the density of the refrigerant that joins the refrigerant in the middle of compression of the compression rotation element. A sufficient flow rate of the refrigerant flowing through the heat exchanger can be secured.

Therefore, even in the heating operation mode after the defrosting operation mode is executed under the high humidity outside air temperature condition where the amount of frost formation is large, the heating capacity can be rapidly increased and the decrease in the heating capacity of the heating operation can be suppressed. Can be provided.

The second invention includes, in particular, in the first invention, a low pressure side detection unit that detects the temperature of the refrigerant on the low pressure side of the main refrigerant circuit or the pressure of the refrigerant on the low pressure side of the main refrigerant circuit. The control device determines the opening degree of the first expansion device and the opening degree of the second expansion device during a period in which the detection value of the low pressure side detection unit is equal to or less than a predetermined value from the start of execution of the heating operation mode. The refrigerant flow rate flowing through the first expansion device is set to be smaller than the refrigerant flow rate flowing through the second expansion device.

As a result, when the amount of heat that can be absorbed by the heat source side heat exchanger is small, the refrigerant flow rate flowing through the bypass refrigerant circuit becomes larger than the refrigerant flow rate flowing through the main refrigerant circuit, and the refrigerant flowing through the bypass refrigerant circuit exchanges heat on the heat source side. Since the pressure is higher than the refrigerant of the main refrigerant circuit sucked from the device to the compression mechanism, the refrigerant density is also high, and the mass flow rate of the refrigerant flowing through the bypass refrigerant circuit also increases, so the heat exchanger on the user side is discharged from the compression mechanism. Not only can the total flow rate of the refrigerant flowing into the refrigerator be increased, but also the heating capacity of the heat exchanger on the user side can be increased.

When the accumulator is provided, the liquid refrigerant staying in the accumulator evaporates, and when the main refrigerant circuit circulates, the pressure on the low pressure side of the main refrigerant circuit rises, so that the low pressure side of the main refrigerant circuit When the pressure of the accumulator rises to a predetermined value set in advance, it can be determined that the accumulator's stagnant liquid refrigerant has run out. In that case, the opening degree of the first expansion device and the second expansion device in the normal heating operation mode. It is possible to switch to the opening of the inflator.

The third invention, in particular, in the first invention, includes a temperature thermista that detects the temperature of the air passing through the heat source side heat exchanger, and the control device has a predetermined time from the start of execution of the heating operation mode. Within, the opening degree of the first expansion device and the opening degree of the second expansion device are set to an opening degree at which the flow rate of the refrigerant flowing through the first expansion device is smaller than the flow rate of the refrigerant flowing through the second expansion device. It is what you are doing.

As a result, when the amount of heat that can be absorbed by the heat source side heat exchanger is small, the refrigerant flow rate flowing through the bypass refrigerant circuit becomes larger than the refrigerant flow rate flowing through the main refrigerant circuit, and the refrigerant flowing through the bypass refrigerant circuit exchanges heat on the heat source side. Since the pressure is higher than the refrigerant of the main refrigerant circuit sucked from the device to the compression mechanism, the refrigerant density is also high, and the mass flow rate of the refrigerant flowing through the bypass refrigerant circuit also increases, so the heat exchanger on the user side is discharged from the compression mechanism. Not only can the total flow rate of the refrigerant flowing into the refrigerator be increased, but also the heating capacity of the heat exchanger on the user side can be increased.

If the accumulator is provided, the liquid refrigerant staying in the accumulator evaporates, and when the main refrigerant circuit circulates, the pressure on the low pressure side of the main refrigerant circuit rises, so the execution of the heating operation mode is started. It can be inferred that the accumulator's stagnant liquid refrigerant has run out after a predetermined time has elapsed, and in that case, the opening degree of the first expansion device and the opening degree of the second expansion device in the normal heating operation mode are set. You can switch.

In the fourth aspect of the invention, particularly in any one of the first to third inventions, in the defrosting operation mode, the refrigerant discharged from the compression rotation element is the heat exchanger on the utilization side and the first expansion device. It is characterized in that the heat flows in the order of the heat exchanger on the heat source side.

As a result, even during the execution of the defrosting operation mode, the high-temperature discharged refrigerant flows through the heat exchanger on the user side, so that the temperature drop of the heat exchanger on the user side is suppressed, and the heating executed after the execution of the defrosting operation mode is completed. In the operation mode, the temperature rise of the heat exchanger on the user side can be promoted, and the heating capacity can be quickly increased even in the heating operation mode after the defrosting operation mode is executed under the high humidity outside air temperature condition where the amount of defrosting is large.

The fifth invention is characterized in that carbon dioxide is used as the refrigerant in any one of the first to fourth inventions.

This makes it possible to raise the temperature of the user-side heat medium when the user-side heat medium is heated by the refrigerant in the user-side heat exchanger.

The sixth invention is a liquid heating apparatus comprising the refrigerating cycle apparatus of any one of the first to fifth inventions and a utilization side heat medium circuit for circulating the utilization side heat medium by a transfer apparatus. Is.

This makes it possible to provide a liquid heating device capable of realizing a high temperature of the user side heat medium when the user side heat medium is heated by the refrigerant.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment.

(Embodiment 1)
FIG. 1 shows a block diagram of a liquid heating device according to the first embodiment of the present invention. The liquid heating device is composed of a refrigerating cycle device 1, a heat medium circuit 5 on the user side, and a control device 4 for controlling the operation of the liquid heating device. Further, the refrigerating cycle device 1 includes a main refrigerant circuit 2 and a control device 4. It is composed of a bypass refrigerant circuit 3.

The main refrigerant circuit 2 includes a compression mechanism 21, a radiator (heat exchanger on the user side) 22, a heat exchanger for cooling (intermediate heat exchanger) 26, a main expansion valve (first expansion device) 23, and an evaporator (heat source side). The heat exchanger) 24 is formed by being sequentially connected by a pipe 16, and uses carbon dioxide (CO2) as a refrigerant.

Although carbon dioxide is optimally used as the refrigerant, for example, a non-azeotropic mixed refrigerant such as R407C, a pseudo-azeotropic mixed refrigerant such as R410A, or a single refrigerant such as R32 can also be used.

The compression mechanism 21 that compresses the refrigerant is composed of a low-stage side compression rotation element 21a and a high-stage side compression rotation element 21b. The radiator 22 heats the heat medium on the utilization side with the refrigerant discharged from the compression rotation element 21b on the high stage side. The volume ratio of the low-stage compression rotation element 21a and the high-stage compression rotation element 21b constituting the compression mechanism 21 is constant, and the drive shaft (not shown) is shared and arranged in one container. It consists of one compressor.

In the present embodiment, the compression rotation element will be described using the compression mechanism 21 composed of the low-stage side compression rotation element 21a and the high-stage side compression rotation element 21b, but in a single compression rotation element. Also applicable, in the case of a single compression rotation element, the position where the refrigerant from the bypass refrigerant circuit 3 merges is in the middle of compression of the compression rotation element, and the compression rotation to the position where the refrigerant from the bypass refrigerant circuit 3 merges. The element can be a low-stage compression rotation element 21a, and the compression rotation element after the position where the refrigerant from the bypass refrigerant circuit 3 joins can be applied as the high-stage compression rotation element 21b.

Further, the compression mechanism 21 may be configured in which the low-stage compression rotation element 21a and the high-stage side compression rotation element 21b are each composed of two independent compressors.

The bypass refrigerant circuit 3 is branched from the pipe 16 between the radiator 22 and the main expansion valve 23, and is connected to the pipe 16 between the low-stage side compression rotation element 21a and the high-stage side compression rotation element 21b. ..

The bypass refrigerant circuit 3 is provided with a bypass expansion valve (second expansion device) 31. A part of the high-pressure refrigerant after passing through the radiator 22 or a part of the high-pressure refrigerant after passing through the cooling heat exchanger 26 is decompressed by the bypass expansion valve 31 to become an intermediate pressure refrigerant, and then for cooling. The heat exchanger 26 exchanges heat with the high-pressure refrigerant flowing through the main refrigerant circuit 2, and merges with the refrigerant between the low-stage side compression rotation element 21a and the high-stage side compression rotation element 21b.

Further, an accumulator 25 for separating gas and liquid is provided between the outlet side of the evaporator 24 and the suction side of the compression mechanism 21. Further, in the main refrigerant circuit 2, there are four-way valves for switching the flow path of the high-pressure refrigerant discharged from the compression mechanism 21 to the radiator 22 side or the evaporator 24 side in the main refrigerant circuit 2. A valve 27 is provided.

In the user-side heat medium circuit 5, the heat medium return pipe 53 and the heat medium forward pipe 54 are connected to the radiator 22. The heat medium return pipe 53 is provided with a transfer pump (conveyor device) 55. By operating the transfer pump 55, the user-side heat medium is supplied to the radiator 22 through the heat medium return tube 53, and the user-side heat medium heated by the radiator 22 is transferred from the heat medium forward tube 54, for example. It is supplied to heaters such as floor heaters (not shown) and hot water storage tanks (not shown).

As a result, heating and hot water supply are performed. After that, the heat medium on the user side is configured to return to the radiator 22 again via the heat medium return tube 53. Water or antifreeze is used as the heat medium on the user side.

Further, the low pressure side piping 16 of the main refrigerant circuit 2 connecting the downstream side of the main expansion valve 23 of the main refrigerant circuit 2 and the suction side of the compression mechanism 21 is provided with the evaporation pressure on the low pressure side as the low pressure side detection unit. A pressure sensor 51 for detecting is provided.

The low-pressure side detection unit is provided in the low-pressure side pipe 16 of the main refrigerant circuit 2 that connects the downstream side of the main expansion valve 23 of the main refrigerant circuit 2 and the suction side of the compression mechanism 21 to the low-pressure side. An evaporation temperature thermistor (not shown) that detects the evaporation temperature of the refrigerant in the gas-liquid two-layer state may be used.

Further, a temperature thermistor 28 is provided around the evaporator 24, and the temperature of the air that supplies heat to the evaporator 24 is detected by using the temperature thermistor 28 by driving the fan 29.

Further, in the refrigerating cycle device 1 of the present embodiment, in the normal operation mode, the transfer pump 55 is operated, the heat medium on the user side is circulated in the heat medium circuit 5 on the user side via the radiator 22, and the compression mechanism is used. A heating operation mode in which the heat medium on the utilization side circulated in the radiator 22 is heated by the refrigerant discharged from the high-stage compression / rotation element 21b of the 21 and the refrigerant discharged from the high-stage compression / rotation element 21b of the compression mechanism 21. It has a defrosting operation mode for defrosting the evaporator 24.

In the defrosting operation mode, when the detection pressure of the pressure sensor 51 or the detection temperature of the evaporation temperature thermista is equal to or less than the first predetermined value, or the heat is supplied to the evaporator 24 detected by the temperature thermista 28. If the temperature of the air is equal to or less than the first predetermined value and the execution time of the heating operation mode continues for a predetermined time or longer in that state, it is determined that the evaporator 24 is frosted, and the higher stage of the compression mechanism 21 is determined. The frost on the evaporator 24 is melted and removed by the heat of the refrigerant discharged from the side compression rotating element 21b.

In FIG. 1, a solid line arrow indicates the flow direction of the refrigerant when the normal heating operation mode is executed. Hereinafter, the change in the state of the refrigerant when the normal heating operation mode is executed will be described.

The high-pressure refrigerant discharged from the compression mechanism 21 flows into the radiator 22 via the four-way valve 27 and dissipates heat to the heat medium on the user side passing through the radiator 22. The high-pressure refrigerant flowing out of the radiator 22 is distributed to the cooling heat exchanger 26 side and the bypass expansion valve 31 side. The high-pressure refrigerant flowing into the cooling heat exchanger 26 is cooled by the intermediate-pressure refrigerant decompressed by the bypass expansion valve 31.

The high-pressure refrigerant distributed to the main expansion valve 23 side is decompressed by the main expansion valve 23 to expand, and then flows into the evaporator 24. The low-pressure refrigerant that has flowed into the evaporator 24 absorbs heat from the air in the evaporator 24.

On the other hand, the high-pressure refrigerant distributed to the bypass expansion valve 31 side is decompressed by the bypass expansion valve 31 and expanded, and then flows into the cooling heat exchanger 26. The intermediate pressure refrigerant flowing into the cooling heat exchanger 26 is heated by the high pressure refrigerant flowing out from the radiator 22. After that, the intermediate pressure refrigerant flowing out of the cooling heat exchanger 26 merges with the intermediate pressure refrigerant discharged from the low stage side compression rotation element 21a of the compression mechanism 21, and is sucked into the high stage side compression rotation element 21b.

The configuration of the refrigeration cycle device 1 of the present embodiment reduces the compression power of the low-stage compression rotary element 21a by bypassing a part of the high-pressure refrigerant via the cooling heat exchanger 26 during the heating operation. At the same time, the increase in the refrigerant density due to the decrease in the enthalpy of the suction refrigerant of the high-stage compression rotating element 21b of the compression mechanism 21 increases the flow rate of the refrigerant flowing through the radiator 22 to improve the heating capacity or the coefficient of performance. Is for.

However, when the heating operation mode is executed in this way, moisture and the like in the air freeze and frost in the evaporator 24, resulting in a decrease in the heating capacity and a decrease in the coefficient of performance due to a decrease in the heat transfer performance of the evaporator 24.

Therefore, when the detection pressure of the pressure sensor 51 or the detection temperature of the evaporation temperature thermista is equal to or less than the first predetermined value, or the temperature of the air supplying heat to the evaporator 24 detected by the temperature thermista 28. Is less than or equal to the first predetermined value, and if the execution time of the heating operation mode continues for a predetermined time or longer in that state, it is determined that the evaporator 24 is frosted, and the compression rotation on the higher stage side of the compression mechanism 21 is performed. It is necessary to execute the defrosting operation mode in which the frost on the evaporator 24 is melted and removed by the heat of the refrigerant discharged from the element 21b.

As a typical method of the defrosting operation mode, the flow path through which the four-way valve 27 communicates is switched with respect to the execution of the heating operation mode to reverse the circulation direction of the refrigerant, and the high temperature discharged from the compression mechanism 21. There is a reverse cycle defrosting method in which a high-pressure refrigerant is allowed to flow into the evaporator 24 and the frost of the evaporator 24 is melted by the heat of condensation thereof.

On the other hand, without switching the four-way valve 27, the flow path through which the four-way valve 27 communicates is the same as in the heating operation mode, and the high-temperature and high-pressure refrigerant discharged from the compression mechanism 21 flows into the radiator 22 to flow the main expansion valve 23. The opening degree of the main expansion valve 23 is increased, and the high-temperature and high-pressure gas refrigerant discharged from the compression mechanism 21 is passed through the main expansion valve 23 without being depressurized, and then flows into the evaporator 24. There is also a hot gas defrosting method that melts the frost of the evaporator 24.

In the present embodiment, the defrosting operation mode is executed by using the hot gas defrosting method, and the change in the state of the refrigerant in that case will be described with reference to FIG.

The broken line arrow shown in FIG. 1 indicates the flow direction of the refrigerant when the defrosting operation mode is executed by using the hot gas defrosting method.

The high-pressure refrigerant discharged from the compression mechanism 21 flows into the radiator 22 through the four-way valve 27, and the refrigerant flowing out from the radiator 22 flows into the evaporator 24 after passing through the main expansion valve 23 and accumulates frost. Dissipates heat to melt the frost. The gas-liquid two-phase refrigerant radiated and discharged by the evaporator 24 enters the accumulator 25, where the gas-liquid is separated and the gas-liquid refrigerant returns to the compression mechanism 21 again.

In this case, since the high-temperature discharged refrigerant flows through the radiator 22 even during the defrosting operation mode, the temperature drop of the radiator 22 is suppressed, and the heating capacity in the heating operation mode started after the defrosting operation mode is executed. Increases faster than in reverse cycle defrosting operation.

Further, in order to improve the defrosting efficiency, the circulation of the heat medium on the utilization side flowing through the radiator 22, that is, the operation of the transfer pump 55 is stopped, or the operating rotation speed of the transfer pump 55 is lowered to reduce the operation speed on the utilization side. The opening degree of the main expansion valve 23 is to reduce the flow rate of the heat medium through the radiator 22 to reduce the amount of heat radiated to the heat medium on the user side and to suppress the temperature drop of the refrigerant flowing into the evaporator 24. It is operated by opening it wide and reducing the amount of decompression.

As described above, the defrosting operation mode is indispensable for stably continuing the heating operation mode, but on the other hand, while the defrosting operation mode is being executed, the evaporator 24 absorbs the refrigerant to evaporate. Since there is no calorific value, the liquid phase refrigerant condensed by the evaporator 24 stays in the accumulator 25.

As a result, at the start of execution of the heating operation mode after the execution of the defrosting operation mode is completed, the suction pressure of the compression mechanism 21 is lowered, and the flow rate of the refrigerant flowing through the radiator 22 is not sufficiently secured, so that the heating capacity is lowered. Will end up. Due to the temperature decrease of the heat medium on the user side caused by this heating capacity, problems such as a decrease in the heating capacity and the coefficient of performance of the heat medium on the user side arise.

In order to solve these problems, at the start of execution of the heating operation mode after the execution of the defrosting operation mode, the liquid phase refrigerant accumulated in the accumulator 25 during the execution of the defrosting operation mode evaporates in a short time. At the same time, it is necessary to quickly secure a sufficient flow rate of the refrigerant flowing through the radiator 22.

Therefore, in the present embodiment, in the control device 4, the flow rate of the refrigerant flowing on the main expansion valve 23 side expands by bypass at the start of the execution of the heating operation mode in which the transfer pump 55 starts the operation after the execution of the defrosting operation mode ends. The valve opening degrees of the main expansion valve 23 and the bypass expansion valve 31 are adjusted so as to be smaller than the flow rate of the refrigerant flowing on the valve 31 side.

As a result, as shown in FIG. 2, the enthalpy of the refrigerant at the outlet of the evaporator 24 increases from point a to point a', so that the refrigerant having high enthalpy flows into the accumulator 25. Therefore, by mixing the refrigerant in the accumulator 25, the evaporation of the retained liquid phase refrigerant is promoted, and the retained refrigerant is reduced in a short time.

Further, by reducing the flow rate of the refrigerant flowing on the main expansion valve 23 side, the flow rate of the refrigerant flowing in the bypass refrigerant circuit 3 increases, and the height of the compression mechanism 21 increases from the point b to the point b'as shown in FIG. The suction pressure of the stage-side compression rotation element 21b increases, and the refrigerant density increases. Therefore, the flow rate of the refrigerant discharged from the compression rotation element 21b on the high stage side increases, and as shown in FIG. 2, the discharge pressure rises from the point c to the point c', so that the utilization side flowing through the radiator 22 The temperature difference with the heat medium increases.

In this way, the control device 4 appropriately adjusts the flow rate ratio between the flow rate of the refrigerant flowing on the main expansion valve 23 side and the flow rate of the refrigerant flowing on the bypass expansion valve 31 side, that is, the valve opening degree of the main expansion valve 23 and the bypass expansion. By appropriately adjusting the valve opening degree of the valve 31, the enthalpy of the refrigerant at the outlet of the evaporator 24 is increased, the evaporation of the liquid refrigerant is promoted, and the suction refrigerant density of the high-stage compression rotating element 21b is increased. By doing so, the heating capacity is increased, so that the heating capacity in the heating operation mode executed after the execution of the defrosting operation mode is completed can be quickly increased while the decrease in the coefficient of performance is suppressed.

Hereinafter, the operation of the valve opening degrees of the main expansion valve 23 and the bypass expansion valve 31 in the heating operation mode executed after the execution of the defrosting operation mode is completed will be described with reference to the flowchart shown in FIG.

First, the control device 4 melts the frost adhering to the evaporator 24 by executing the defrosting operation mode, and then ends the execution of the defrosting operation mode (step S1).

Then, while the pulling continuous compression mechanism 21 is operating, the valve opening degree of the main expansion valve 23 and the valve opening degree of the bypass expansion valve 31 are set to Om and Ob, which are set in advance in the control device 4, respectively. (Step S2).

As shown in FIG. 1, the valve opening degree Om of the main expansion valve 23 and the valve opening degree Ob of the bypass expansion valve 31 are such that the refrigerant flow rate Gm flowing through the main expansion valve 23 is the refrigerant flow rate Gb flowing through the bypass expansion valve 31. The opening degree is smaller (step S2).

When the defrosting operation mode is executed, the high-temperature and high-pressure refrigerant discharged from the compression mechanism 21 is used with the valve opening of the main expansion valve 23 at a substantially maximum opening and the valve opening of the bypass expansion valve 31 being abbreviated. With the minimum opening degree, the high-temperature and high-pressure gas refrigerant discharged from the compression mechanism 21 is allowed to flow into the evaporator 24.

Therefore, at the start of the execution of the heating operation mode in which the transfer pump 55 in step S2 starts to operate, the control device 4 operates the valve opening of the main expansion valve 23 in the closing direction, and the valve opening of the bypass expansion valve 31. Will be operated in the open direction.

Immediately after setting the valve opening of the main expansion valve 23 and the valve opening of the bypass expansion valve 31 to be Om and Ob, which are set in advance in the control device 4, the transfer pump 55 is operated. , The execution of the heating operation mode may be started.

Next, the control device 4 detects the low pressure side pressure Ps of the main refrigerant circuit 2 by the pressure sensor 51 which is the low pressure side detection unit (step S3).

Then, the pressure sensor 51 detects the low pressure side pressure Ps of the main refrigerant circuit 2, that is, the suction pressure of the compression mechanism 21 (the suction pressure of the low stage side compression rotation element 21a), and the detected value is set in advance. It is determined while monitoring whether or not it is equal to or less than the second predetermined value (predetermined pressure Pst) (step S4).

If YES in step S4, that is, if the suction pressure Ps is Pst or less, which is the second predetermined value, the valve opening of the main expansion valve 23 and the valve opening of the bypass expansion valve 31 are set in advance by the control device 4. Leave the Om and Ob set in.

That is, the state in which the refrigerant flow rate Gm flowing through the main expansion valve 23 is smaller than the refrigerant flow rate Gb flowing through the bypass expansion valve 31 is continued.

On the other hand, when NO in step S4, that is, when the suction pressure Ps is higher than Pst, which is the second predetermined value, the valve opening of the main expansion valve 23 and the valve opening of the bypass expansion valve 31 are controlled in advance. The control of Om and Ob set in 4 is canceled, and the operation control of the valve opening of the main expansion valve 23 and the valve opening of the bypass expansion valve 31 in the normal heating operation mode is performed, and the heating operation mode is set. Continue execution.

As the low-pressure side detection unit, instead of the pressure sensor 51, the low-pressure side pipe of the main refrigerant circuit 2 that connects the downstream side of the main expansion valve 23 of the main refrigerant circuit 2 and the suction side of the compression mechanism 21. An evaporation temperature thermistor (not shown) provided in 16 and detecting the evaporation temperature of the refrigerant in the gas-liquid two-layer state on the low pressure side may be used.

In this case, as in the flowchart shown in FIG. 3 using the pressure sensor 51, the valve opening of the main expansion valve 23 and the valve opening of the bypass expansion valve 31 are during the period when the detection value of the evaporation temperature thermistor is equal to or less than the second predetermined value. The degree is set to an opening degree at which the flow rate of the refrigerant flowing through the main expansion valve 23 is smaller than the flow rate of the refrigerant flowing through the bypass expansion valve 31.

Further, a temperature thermistor 28 is provided around the evaporator 24, and the temperature of the air that supplies heat to the evaporator 24 is detected by using the temperature thermistor 28 by driving the fan 29.

Then, using the temperature thermistor 28 instead of the low pressure side detection unit, the control device 4 uses the valve opening of the main expansion valve 23 and the valve of the bypass expansion valve 31 within a predetermined time from the start of execution of the heating operation mode. The opening degree may be set to an opening degree in which the flow rate of the refrigerant flowing through the main expansion valve 23 is smaller than the flow rate of the refrigerant flowing through the bypass expansion valve 31.

In this case, after a predetermined time has elapsed from the start of execution of the heating operation mode, the operation control of the valve opening of the main expansion valve 23 and the valve opening of the bypass expansion valve 31 in the normal heating operation mode is performed, and heating is performed. The execution of the operation mode will be continued.

In the present embodiment, the valve opening degree Om of the main expansion valve 23 and the valve opening degree Ob of the bypass expansion valve 31 are set in advance in the control device 4, but the valve opening degree Om and the valve are configured. The opening degree Ob may be controlled so that the flow rate is actually detected and the main refrigerant flow rate Gm <bypass refrigerant flow rate Gb.

As a flow rate detecting device (not shown) in that case, for example, a flow meter may be provided in the refrigerant circuit on the main expansion valve 23 side and the bypass path, respectively, and the pressure difference and opening degree of the inlet / outlet of each expansion valve may be provided. The flow rate of each refrigerant may be calculated from the function.

The bypass refrigerant circuit 3 does not necessarily have to branch from the main refrigerant circuit 2 between the radiator 22 and the cooling heat exchanger 26, and is mainly between the cooling heat exchanger 26 and the main expansion valve 23. It may be branched from the refrigerant circuit 2.

Further, the main expansion valve 23 and the bypass expansion valve 31 of the present embodiment do not necessarily have to be expansion valves, and may be an expansion machine that recovers power from the expanding refrigerant. In this case, for example, the rotation speed of the expander may be controlled by changing the load by a generator connected to the expander.

As described above, the refrigerating cycle apparatus according to the present invention comprises a main refrigerant circuit provided with an intermediate heat exchanger and a bypass refrigerant circuit, and at the time of executing the heating operation after the execution of the defrosting operation of the heat source side heat exchanger is completed. However, since it is possible to suppress a decrease in the heating capacity of the heating operation, it is useful for refrigeration, air conditioning, hot water supply, heating equipment, etc. using a refrigeration cycle device.

1 Refrigerant cycle device 2 Main refrigerant circuit 3 Bypass refrigerant circuit 4 Control device 5 User side heat medium circuit 16 Piping 21 Compression mechanism 21a Low stage compression rotation element 21b High stage side compression rotation element 22 Heat exchanger (use side heat exchanger)
23 Main expansion valve (first expansion device)
24 Evaporator (heat exchanger on the heat source side)
25 Accumulator 26 Cooling heat exchanger (intermediate heat exchanger)
28 Temperature thermistor 29 Fan 31 Bypass expansion valve (second expansion device)
51 Pressure sensor (low pressure side detector)
53 Heat medium return pipe 54 Heat medium forward pipe 55 Conveyance pump (conveyor device)

Claims (5)

The compression mechanism composed of the compression rotation element, the utilization side heat exchanger that heats the utilization side heat medium by the refrigerant discharged from the compression rotation element, the intermediate heat exchanger, the first expansion device, and the heat source side heat exchanger are piped. The main refrigerant circuit formed by connecting sequentially with
After being branched from the pipe between the user-side heat exchanger and the first expansion device and decompressed by the second expansion device, the intermediate heat exchanger exchanges heat with the refrigerant flowing through the main refrigerant circuit. A bypass refrigerant circuit that joins the refrigerant in the process of compression of the compression rotating element,
With the control device
Equipped with
A heating operation mode in which the heat medium on the user side is heated by the refrigerant discharged from the compression rotation element in the heat exchanger on the user side.
It has a defrosting operation mode in which the heat exchanger on the heat source side is defrosted by the refrigerant discharged from the compression rotating element.
In the heating operation mode executed after the execution of the defrosting operation mode is completed,
For at least a predetermined period from the start of execution of the heating operation mode,
At each predetermined opening degree, the flow rate of the refrigerant flowing through the first expansion device is smaller than the flow rate of the refrigerant flowing through the second expansion device.
The control device is a refrigerating cycle device characterized in that the opening degree of the first expansion device and the opening degree of the second expansion device are set. The control device includes a low pressure side detection unit that detects the temperature of the refrigerant on the low pressure side of the main refrigerant circuit or the pressure of the refrigerant on the low pressure side of the main refrigerant circuit, and the control device starts from the start of execution of the heating operation mode. During the period when the detection value of the low pressure side detection unit is equal to or less than a predetermined value, the opening degree of the first expansion device and the opening degree of the second expansion device are set, and the flow rate of the refrigerant flowing through the first expansion device is the first. 2. The refrigerating cycle device according to claim 1, wherein the opening degree is set to be smaller than the flow rate of the refrigerant flowing through the expansion device. Claim 1 or 2 characterized in that, in the defrosting operation mode, the refrigerant discharged from the compression rotation element flows in the order of the utilization side heat exchanger, the first expansion device, and the heat source side heat exchanger. The refrigeration cycle device described in. The refrigerating cycle apparatus according to any one of claims 1 to 3 , wherein carbon dioxide is used as the refrigerant. A liquid heating device comprising the refrigerating cycle device according to any one of claims 1 to 4 and a user-side heat medium circuit for circulating the user-side heat medium by a transfer device.

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