JP7225178B2 - Heat source machine and its control method - Google Patents

Description

The present disclosure relates to a heat source device suitable for use in, for example, a heat pump chiller, and a control method thereof.

A heat pump chiller is used as one of the heat source machines for industrial use. When hot water is supplied by using a heat pump chiller in heating operation, particularly when the outside air temperature is low, the pressure ratio tends to be high and the temperature of the refrigerant discharged from the compressor tends to be high. Further, when a low boiling point refrigerant such as R32 is used as a refrigerant with a low global warming potential (GWP), the refrigerant discharge temperature is further increased. If the refrigerant discharge temperature rises, it becomes difficult to reuse conventional components that have been used for refrigerants other than low-boiling-point refrigerants.

In Patent Document 1, a portion of the refrigerant introduced from the indoor unit is expanded by an expansion device to form a gas-liquid two-phase refrigerant, and this two-phase refrigerant is supplied to the refrigerant suction side of the compressor, thereby increasing the refrigerant discharge temperature. It is disclosed to reduce

Japanese Patent No. 6005255

However, in Patent Document 1, since a gas-liquid two-phase refrigerant is used as the cooling refrigerant, the specific volume of the refrigerant is larger than that of the liquid refrigerant, and the pipe diameter is increased. This not only fails to improve handling properties, but also fails to reduce costs.

When the cooling operation is performed in addition to the heating operation by the heat pump, there is a problem that the refrigerant to be used becomes redundant because the required amount of refrigerant differs for each operation.

In Patent Literature 1, a throttle device is provided in a pipe for guiding gas-liquid two-phase refrigerant for cooling, and the degree of opening of the throttle device is controlled. However, it is complicated to control the opening degree of the expansion device in addition to controlling the expansion valve of the main refrigerant circuit.

The present disclosure has been made in view of such circumstances, and provides a heat source device capable of reducing the diameter of a pipe for supplying a cooling refrigerant leading to the suction side of a compressor, and a control method thereof. With the goal.
Another object of the present invention is to provide a heat source device capable of reducing the amount of refrigerant used even in a heat source device that performs heating operation and cooling operation, and a method of controlling the same.
Another object of the present invention is to provide a heat source device capable of supplying cooling refrigerant to the suction side of a compressor with simple control, and a control method thereof.

A heat source device according to an aspect of the present disclosure includes a compressor that compresses a refrigerant, a heat medium heat exchanger that exchanges heat between the refrigerant and a heat medium, an expansion valve that expands the refrigerant, an air heat exchanger that exchanges heat between refrigerant and air; and a liquid bypass pipe that is connected at its upstream end between the heat medium heat exchanger and the expansion valve and guides the liquid refrigerant to the suction side of the compressor; It has

A heat source device control method according to an aspect of the present disclosure includes a compressor that compresses a refrigerant, a heat medium heat exchanger that exchanges heat between the refrigerant and a heat medium, an expansion valve that expands the refrigerant, and a refrigerant and air. a liquid bypass pipe whose upstream end is connected between the heat medium heat exchanger and the expansion valve and guides the liquid refrigerant to the suction side of the compressor; and the liquid bypass pipe and a liquid bypass valve provided in the heat medium, guides the refrigerant discharged from the compressor during the heating operation to heat the heat medium to the heat medium heat exchanger, and from the compressor during the cooling operation to cool the heat medium. and a switching valve for guiding the discharged refrigerant to the air heat exchanger, wherein the temperature of the air around the air heat exchanger is a predetermined value during the heating operation. Control the liquid bypass valve from closed to open when:

It is possible to reduce the diameter of the piping that supplies the cooling refrigerant leading to the suction side of the compressor.
It is possible to reduce the amount of refrigerant used even in a heat source device that performs heating operation and cooling operation.
The refrigerant for cooling can be supplied to the suction side of the compressor with simple control.

1 is a schematic configuration diagram showing a refrigerant circuit according to a first embodiment of the present disclosure during heating operation; FIG. 1 is a schematic configuration diagram showing a refrigerant circuit according to a first embodiment of the present disclosure during cooling operation; FIG. FIG. 6 is a schematic configuration diagram showing a refrigerant circuit according to a second embodiment of the present disclosure during heating operation; FIG. 6 is a schematic configuration diagram showing a refrigerant circuit according to a second embodiment of the present disclosure during cooling operation; FIG. 11 is a graph showing a ph diagram of a refrigerant circuit according to a third embodiment of the present disclosure; FIG. FIG. 11 is a schematic configuration diagram showing a refrigerant circuit showing a modified example of the third embodiment of the present disclosure;

Each embodiment according to the present disclosure will be described below with reference to the drawings.

[First embodiment]
A first embodiment of the present disclosure will be described below with reference to FIGS. 1 and 2. FIG.
1 and 2 show the refrigerant circuit configuration of a chiller (heat source machine) 1 of this embodiment. The chiller 1 can perform heating operation and cooling operation by switching a four-way valve (switching valve) 4 provided on the discharge side of the compressor 3 . The heating operation is an operation in which the water heat exchanger (heat medium heat exchanger) 5 heats water (heat medium), and the cooling operation is an operation in which the water heat exchanger 5 cools water. FIG. 1 shows a refrigerant circuit for heating operation, and FIG. 2 shows a refrigerant circuit for cooling operation.

The chiller 1 uses, for example, R32 as a refrigerant. R32 is a refrigerant with a low boiling point and a low global warming potential (GWP). In addition, it is good also as replacing with R32 and using another refrigerant|coolant.

The chiller 1 includes a compressor 3 that compresses the refrigerant, a four-way valve 4, a water heat exchanger 5, a first expansion valve 6, a receiver 7, a second expansion valve 8, an air heat exchanger 9, an accumulator 10; A refrigeration cycle is performed by connecting the compressor 3, the four-way valve 4, the water heat exchanger 5, the first expansion valve 6, the receiver 7, the second expansion valve 8, the air heat exchanger 9, and the accumulator 10 with refrigerant piping. A refrigerant circuit is configured.

The compressor 3 is, for example, a scroll compressor or a rotary compressor, and a compression mechanism 3b such as a scroll compression mechanism or a rotary compression mechanism is provided in a housing 3a of the compressor 3 . The compression mechanism 3b is driven by an electric motor (not shown). The electric motor has an inverter device, and the rotation speed is arbitrarily changed according to a command from a control unit (not shown).

A discharge temperature sensor 14 for measuring the discharge temperature of the refrigerant is provided on the discharge side of the compressor 3 . The output of the discharge temperature sensor 14 is transmitted to the controller.

The four-way valve 4 is switched so that the refrigerant discharged from the compressor 3 is guided to the water heat exchanger 5 during heating operation (Fig. 1), and the refrigerant discharged from the compressor 3 is transferred to the air heat exchanger during cooling operation. 9 (FIG. 2). The four-way valve 4 is controlled by a controller (not shown).

The water heat exchanger 5 operates as a condenser during heating operation (FIG. 1) and operates as an evaporator during cooling operation (FIG. 2). A water pipe 16 is connected to the water heat exchanger 5 for circulating water between it and an external load. The water guided from the water pipe 16 and the refrigerant are heat-exchanged in the water heat exchanger 5 .

The first expansion valve 6 expands the refrigerant condensed and liquefied in the water heat exchanger 5 when operating as a condenser as shown in FIG. The degree of opening of the first expansion valve 6 is controlled by the controller.

The second expansion valve 8 expands the refrigerant condensed and liquefied in the air heat exchanger 9 when operating as a condenser as shown in FIG. The degree of opening of the second expansion valve 8 is controlled by the controller.

The receiver 7 is provided between the first expansion valve 6 and the second expansion valve 8 and is a container that temporarily stores a portion of the refrigerant expanded by the first expansion valve 6 or the second expansion valve 8. . The capacity (size) of the receiver 7 is determined according to the amount of refrigerant circulating in the refrigerant circuit.

The air heat exchanger 9 operates as an evaporator during heating operation (FIG. 1) and operates as a condenser during cooling operation (FIG. 2). The air heat exchanger 9 exchanges heat between the refrigerant and the air. Air is sent from the fan 12 to the air heat exchanger 9 .

The accumulator 10 is provided on the upstream side of the compressor 3, that is, on the refrigerant suction side, and is a container that temporarily stores the refrigerant evaporated in the air heat exchanger 9 or the water heat exchanger 5. FIG.

An upstream end of a liquid bypass pipe 20 is connected between the water heat exchanger 5 and the first expansion valve 6 . A downstream end of the liquid bypass pipe 20 is connected to the suction side of the compression mechanism 3 b of the compressor 3 . Via the liquid bypass valve 22, part of the liquid refrigerant led from the water heat exchanger 5 that operates as a condenser during the heating operation is led to the compression mechanism 3b. That is, the liquid bypass valve 22 bypasses the first expansion valve 6 , the receiver 7 , the second expansion valve 8 , the air heat exchanger 9 and the accumulator 10 .

A liquid bypass valve 22 is provided at an intermediate position of the liquid bypass pipe 20 . The liquid bypass valve 22 is an open/close valve such as an electromagnetic valve, and its opening/closing operation is performed by a control unit.

An outside air temperature sensor 18 is provided inside the housing of the chiller 1 or near the chiller 1 . An outside air temperature sensor measures the outside air temperature. The outside air temperature measured by the outside air temperature sensor 18 is taken as the temperature of the air guided to the air heat exchanger 9 by the fan 12 . The output of the outside air temperature sensor 18 is transmitted to the control section.

The control unit includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a computer-readable storage medium, and the like. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example, and the CPU reads out this program to a RAM or the like, and executes information processing and arithmetic processing. As a result, various functions are realized. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or delivered via wired or wireless communication means. etc. may be applied. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

Next, the operation of the chiller 1 configured as described above will be described.
<Heating operation: Figure 1>
When the water heat exchanger 5 heats water, the four-way valve 4 is switched as shown in FIG. In the water heat exchanger 5, the refrigerant is condensed by exchanging heat with water guided from the water pipe 16. FIG. The water is heated by the latent heat as the refrigerant condenses. The heated water is directed to an external load via water line 16 .

The liquid refrigerant condensed in the water heat exchanger 5 is guided to the first expansion valve 6 and expanded. The expanded refrigerant is guided to the receiver 7 and part of the refrigerant is stored in the receiver 7 as surplus refrigerant. Refrigerant taken out from the receiver 7 is led to the air heat exchanger 9 via the second expansion valve 8 .

In the air heat exchanger 9, the refrigerant evaporates by exchanging heat with the air guided by the fan 12. The refrigerant evaporated in the air heat exchanger 9 is led to the accumulator 10 through the four-way valve 4 . The gas refrigerant guided from the accumulator 10 is guided to the suction side of the compressor 3 and compressed again by the compression mechanism 3b.

When the outside temperature measured by the outside temperature sensor 18 becomes a low outside temperature below a predetermined value (for example, 0° C. or below or −5° C. or below), the control unit closes the liquid bypass valve 22 provided in the liquid bypass pipe 20. from closed to open. As a result, part of the liquid refrigerant led from the water heat exchanger 5 is led to the suction side of the compression mechanism 3 b of the compressor 3 via the liquid bypass pipe 20 . By supplying the liquid refrigerant to the suction side of the compression mechanism 3b in this way, the discharge temperature of the refrigerant discharged from the compressor 3 is reduced.

The control of opening and closing of the liquid bypass valve 22 is performed together with the temperature measured by the outside air temperature sensor 18, or instead of the temperature measured by the outside air temperature sensor 18, the temperature measured by the discharge temperature sensor 14, the compression The pressure ratio of machine 3 may be used. For example, when the measured value of the discharge temperature sensor 14 reaches a temperature corresponding to 50° C. of the water heated by the water heat exchanger 5, and/or the pressure ratio of the compressor 3 becomes 4.5 or more. , the liquid bypass valve 22 is controlled from closed to open.

<Cooling operation: Figure 2>
When water is cooled by the water heat exchanger 5, the four-way valve 4 is switched as shown in FIG. In the air heat exchanger 9, the refrigerant is condensed by exchanging heat with the air guided by the fan 12.

The liquid refrigerant condensed in the air heat exchanger 9 is guided to the second expansion valve 8 and expanded. The expanded refrigerant is guided to the receiver 7 and part of the refrigerant is stored in the receiver 7 . Refrigerant taken out from the receiver 7 is led to the water heat exchanger 5 via the first expansion valve 6 .

In the water heat exchanger 5 , the refrigerant evaporates by exchanging heat with water guided from the water pipe 16 . The water cooled by the latent heat of vaporization of the refrigerant is led to the external load via the water pipe 16 .

The refrigerant evaporated in the water heat exchanger 5 is led to the accumulator 10 through the four-way valve 4 . The gas refrigerant guided from the accumulator 10 is guided to the suction side of the compressor 3 and compressed again by the compression mechanism 3b.

The controller keeps the liquid bypass valve 22 closed during the cooling operation. That is, the liquid bypass pipe 20 is not used during the cooling operation.

According to this embodiment, the following effects are obtained.
By guiding the liquid refrigerant to the suction side of the compression mechanism 3b through the liquid bypass pipe 20, the temperature of the refrigerant discharged from the compressor 3 can be lowered. As a result, operation at a high pressure ratio becomes possible, and the usage range of the chiller 1 can be expanded.
Since the liquid refrigerant flows through the liquid bypass pipe 20, the diameter (pipe inner diameter) can be made smaller than that of the two-phase refrigerant mixed with the gas refrigerant. As a result, the cost can be reduced and the piping can be easily routed.

An upstream end of the liquid bypass pipe 20 is provided between the water heat exchanger 5 and the first expansion valve 6 . As a result, the refrigerant before expansion can be reliably guided to the compressor 3 as a liquid refrigerant.
Since part of the liquid refrigerant is bypassed to the compressor 3 by the liquid bypass pipe 20, the capacity (size) of the receiver 7 provided between the first expansion valve 6 and the second expansion valve 8 is reduced. be able to. As a result, space can be saved and costs can be reduced.

When the heating operation is performed and the outside air temperature is lower than a predetermined value, the pressure ratio becomes high (for example, 4.5 or higher), and the temperature of the refrigerant discharged from the compressor 3 may become high. Therefore, under such conditions, the liquid bypass valve 22 is opened to guide the liquid refrigerant to the suction side of the compression mechanism 3b.

[Second embodiment]
Next, a second embodiment of the present disclosure will be described with reference to FIGS. 3 and 4. FIG. Since this embodiment has the same basic configuration as the first embodiment, only the configuration added to the first embodiment will be described below.

As shown in FIGS. 3 and 4, a parallel pipe branching from between the upstream end of the liquid bypass pipe 20 and the first expansion valve 6 and branching from between the second expansion valve 8 and the air heat exchanger 9 A refrigerant pipe 30 is provided. A parallel refrigerant pipe 30 is provided in parallel with the first expansion valve 6 , the receiver 7 and the second expansion valve 8 . Thereby, the parallel refrigerant pipe 30 bypasses the first expansion valve 6 , the receiver 7 and the second expansion valve 8 and connects the water heat exchanger 5 and the air heat exchanger 9 .

A third expansion valve 32 is provided in the parallel refrigerant pipe 30 . The degree of opening of the third expansion valve is controlled by the controller.

Next, the operation of the chiller 1 configured as described above will be described.
<Heating operation: Figure 3>
During the heating operation, the third expansion valve 32 is fully closed by a command from the control section. Therefore, since the parallel refrigerant pipe 30 is not used during the heating operation, the same operation as that of the first embodiment shown in FIG. 1 is performed during the heating operation. When the outside air temperature is low, the liquid bypass valve 22 is opened to reduce the discharge temperature of the liquid refrigerant as in the first embodiment.

<Cooling operation: Fig. 4>
During the cooling operation, the first expansion valve 6 and the second expansion valve 8 are fully closed according to a command from the control unit so that the refrigerant does not flow to the receiver 7 . The liquid bypass valve 22 is also fully closed, and the liquid bypass pipe 20 is not used. Therefore, all of the liquid refrigerant guided from the air heat exchanger 9 is guided to the parallel refrigerant pipe 30 and expanded by the third expansion valve 32 whose opening is controlled by the controller. The refrigerant expanded by the third expansion valve 32 is guided to the water heat exchanger 5 . Since the operation after this is the same as that of FIG. 2 of the first embodiment, it is omitted.

Chiller 1 of this embodiment has the following effects.
A parallel refrigerant pipe 30 is provided in parallel with the first expansion valve 6 , the receiver 7 and the second expansion valve 8 . During the heating operation, the third expansion valve 32 is closed so that the refrigerant flows to the first expansion valve 6 side. As a result, the excess refrigerant can be stored in the receiver 7 during the heating operation.

Further, when the outside air temperature is low, part of the liquid refrigerant can be guided to the compressor 3 using the liquid bypass pipe 20 to bypass the receiver 7 . Thereby, the capacity of the receiver 7 can be reduced.

On the other hand, during the cooling operation, the third expansion valve 32 is opened to allow the refrigerant to flow through the parallel refrigerant pipe 30 but not to the second expansion valve 8 side. As a result, the necessary amount of refrigerant can be used in just the right amount without storing the refrigerant in the receiver 7 during the cooling operation.

As described above, the necessary and sufficient amount of refrigerant can be selected even in the chiller 1 that performs heating operation and cooling operation, and the amount of refrigerant to be used can be reduced.

Further, when the parallel refrigerant pipe 30 is used during the cooling operation, the refrigerant is expanded by the third expansion valve 32, and the refrigerant can be expanded by one expansion valve. Therefore, if only the third expansion valve 32 is used in the parallel refrigerant pipe 30, compared to the case of expansion with two of the first expansion valve 6 and the second expansion valve 8, the difference in pressure (between the water heat exchanger 5 and When the refrigerant differential pressure of the air heat exchanger 9) is relatively small, it is possible to avoid insufficient diameter of the expansion valve.

[Third Embodiment]
Next, a third embodiment of the present disclosure will be described.
Since the chiller 1 of this embodiment can use the configurations of the first embodiment and the second embodiment shown in FIGS. 1 to 4, the description thereof will be omitted.

The control unit of this embodiment controls the opening degree of the first expansion valve 6 so that the temperature of the refrigerant discharged from the compressor 3 is below a predetermined value during the heating operation shown in FIGS. 1 and 3 . Specifically, when the measured value of the discharge temperature sensor 14 exceeds a predetermined value, the degree of opening of the first expansion valve 6 is reduced in the closing direction. Here, the predetermined value means, for example, the temperature measured by the discharge temperature sensor 14 corresponding to the case where the temperature of the water heated by the water heat exchanger 5 is 50°C, or a temperature several degrees Celsius lower than the measured temperature. do.

By narrowing the opening of the first expansion valve 6, the amount of refrigerant circulation is reduced, the condensation capacity in the water heat exchanger 5 is increased, the liquid phase ratio of the refrigerant is increased, and the liquid bypass pipe 20 passes through the compressor. Increase the amount of liquid refrigerant leading to 3. As the amount of liquid refrigerant introduced to the suction side of the compressor 3 increases, the discharge gas temperature decreases.

The above process is shown in the p (pressure)-h (specific enthalpy) diagram of FIG. As shown in the figure, by throttling the first expansion valve 6, the specific enthalpy moves from point _C2 of _HL2 to point _C1 of _HL1 , and the degree of supercooling increases. The refrigerant (L ₁ point) whose degree of supercooling has increased and the amount of liquid refrigerant has increased reaches point A (specific enthalpy H _A ), which is the suction position of the compressor 3, via the liquid bypass pipe 20, and undergoes the first expansion. The refrigerant expanded to point D ₁ in valve 6 and evaporated in air heat exchanger 9 joins with the refrigerant on the suction side of compression mechanism 3b to reach point S ₁ (specific enthalpy H _S1 ). Then, the refrigerant compressed by the compression mechanism 3b becomes high temperature and high pressure and reaches point _B1 .

On the other hand, the refrigerant before the opening degree of the first expansion valve 6 is throttled joins at point _S2 (specific enthalpy H _S2 ) from point _C2 via point _D2 and point _L2 . Then, the refrigerant compressed by the compression mechanism 3b reaches the _B2 point.

As is clear from a comparison of the _B1 point and the _B2 point, the temperature at the _B1 point where the degree of opening of the first expansion valve 6 is reduced is lower than the _B2 point, and the discharge temperature is lower. I understand.
As described above, the discharge temperature can be lowered without controlling the opening of the liquid bypass valve 22 by increasing the degree of supercooling by reducing the opening of the first expansion valve 6 .

The effects of this embodiment are as follows.
By controlling the degree of opening of the first expansion valve 6, the temperature of the refrigerant discharged from the compressor 3 is controlled below a predetermined value. As a result, an on-off valve (solenoid valve) that only opens and closes can be used as the liquid bypass valve 22 instead of a regulating valve with a variable valve opening degree, thereby reducing costs. In addition, since it is unnecessary to adjust the degree of opening of the liquid bypass valve 22, the control can be simplified.

Note that this embodiment can be modified as shown in FIG.
6 corresponds to FIG. 1, and the position of the upstream end of the liquid bypass pipe 20 is different. Other configurations are the same as those in FIG. In this modification, the upstream end of the liquid bypass pipe 20 is connected between the first expansion valve 6 and the receiver 7 . Even with such a configuration, it is possible to control the temperature of the refrigerant discharged by the first expansion valve 6 as in the above-described embodiment.

The heat source equipment and the control method thereof described in each of the embodiments described above are grasped, for example, as follows.

A heat source device according to an aspect of the present disclosure includes (1) a compressor (3) that compresses a refrigerant, a heat medium heat exchanger (5) that exchanges heat between the refrigerant and a heat medium, and a heat medium heat exchanger (5) that expands the refrigerant. An expansion valve (6), an air heat exchanger (9) for exchanging heat between refrigerant and air, and an upstream end connected between the heat medium heat exchanger and the expansion valve to transfer the liquid refrigerant to the compressor. and a liquid bypass pipe (20) leading to the suction side of the.

By guiding the liquid refrigerant to the suction side of the compressor through the liquid bypass pipe, the temperature of the refrigerant discharged from the compressor can be lowered. As a result, operation at a high pressure ratio becomes possible, and the range of use of the heat source equipment can be expanded.
Since the liquid refrigerant flows through the liquid bypass pipe, the diameter (pipe inner diameter) can be made smaller than that of the two-phase refrigerant mixed with the gas refrigerant. As a result, the cost can be reduced and the piping can be easily routed.

Furthermore, in the heat source equipment according to one aspect of the present disclosure, the expansion valves include a first expansion valve provided on the heat medium heat exchanger side and a second expansion valve provided on the air heat exchanger side ( 8), wherein the upstream end of the liquid bypass pipe is connected between the heat medium heat exchanger and the first expansion valve, and is connected between the first expansion valve and the second expansion valve , a receiver (7) for storing refrigerant is provided.

An upstream end of the liquid bypass pipe is provided between the heat medium heat exchanger and the first expansion valve. As a result, the refrigerant before expansion can be reliably guided to the compressor as a liquid refrigerant.
Since part of the liquid refrigerant is bypassed to the compressor by the liquid bypass pipe, the capacity of the receiver provided between the first expansion valve and the second expansion valve can be reduced. As a result, space can be saved and costs can be reduced.

Furthermore, in the heat source equipment according to one aspect of the present disclosure, during the heating operation for heating the heat medium, the refrigerant discharged from the compressor is guided to the heat medium heat exchanger, and during the cooling operation for cooling the heat medium a switching valve for guiding the refrigerant discharged from the compressor to the air heat exchanger; a liquid bypass valve (22) provided in the liquid bypass pipe; and a control unit that controls the liquid bypass valve from closed to open when the temperature of the air around is below a predetermined value.

When the air temperature around the air heat exchanger is set to a predetermined value (e.g., 0°C) or less during heating operation, the pressure ratio becomes high (e.g., 4.5 or more), and the temperature of the refrigerant discharged from the compressor becomes high. There is a possibility that it will be. Therefore, under such conditions, the liquid bypass valve is opened to guide the liquid refrigerant to the suction side of the compressor.

Furthermore, in the heat source equipment according to one aspect of the present disclosure, during the heating operation for heating the heat medium, the refrigerant discharged from the compressor is guided to the heat medium heat exchanger, and during the cooling operation for cooling the heat medium a switching valve that guides the refrigerant discharged from the compressor to the air heat exchanger; a heat medium heat exchanger provided in parallel with the first expansion valve, the receiver, and the second expansion valve; and the air heat exchanger, a third expansion valve (32) provided in the parallel refrigerant pipe, the third expansion valve being closed during the heating operation, and the The degree of opening of the first expansion valve and/or the second expansion valve is controlled so as to flow the refrigerant to the first expansion valve side, and during the cooling operation, the third expansion valve is opened, and the second expansion valve is opened. and a control unit that controls the opening degree of the first expansion valve and/or the second expansion valve so that the refrigerant does not flow to the side.

A parallel refrigerant pipe is provided in parallel with the first expansion valve, the receiver, and the second expansion valve. During the heating operation, the third expansion valve is closed so that the refrigerant flows to the first expansion valve side. As a result, the excess refrigerant can be stored in the receiver during the heating operation. On the other hand, during the cooling operation, the third expansion valve is opened to allow the refrigerant to flow through the parallel refrigerant pipe and not to the second expansion valve side. As a result, during the cooling operation, the required amount of refrigerant can be used in just the right amount without storing the refrigerant in the receiver.
As described above, the necessary and sufficient amount of refrigerant can be selected even in the heat source equipment that performs the heating operation and the cooling operation, and the amount of refrigerant to be used can be reduced.
Further, when parallel refrigerant pipes are used during the cooling operation, the refrigerant is expanded by the third expansion valve, and the refrigerant can be expanded by one expansion valve. Therefore, if the third expansion valve is used in the parallel refrigerant pipe, the difference in pressure (between the heat medium heat exchanger and the air heat exchanger) will be higher than when expansion is performed with the first expansion valve and the second expansion valve. Insufficient diameter of the expansion valve can be avoided when the refrigerant pressure difference) is relatively small.

Furthermore, in the heat source equipment according to one aspect of the present disclosure, during the heating operation for heating the heat medium, the refrigerant discharged from the compressor is guided to the heat medium heat exchanger, and during the cooling operation for cooling the heat medium a switching valve for guiding the refrigerant discharged from the compressor to the air heat exchanger; a liquid bypass valve provided in the liquid bypass pipe and serving as an opening/closing valve; and a control unit that controls the degree of opening of the first expansion valve so that the temperature of the refrigerant that flows is equal to or lower than a predetermined value.

By controlling the degree of opening of the first expansion valve, the temperature of the refrigerant discharged from the compressor is controlled below a predetermined value. As a result, an on-off valve that only opens and closes can be used as the liquid bypass valve instead of a regulating valve that has a variable valve opening degree, and costs can be reduced. In addition, since it is unnecessary to adjust the degree of opening of the liquid bypass valve, the control can be simplified.

A heat source device control method according to an aspect of the present disclosure includes a compressor that compresses a refrigerant, a heat medium heat exchanger that exchanges heat between the refrigerant and a heat medium, an expansion valve that expands the refrigerant, and a refrigerant and air. a liquid bypass pipe whose upstream end is connected between the heat medium heat exchanger and the expansion valve and guides the liquid refrigerant to the suction side of the compressor; and the liquid bypass pipe and a liquid bypass valve provided in the heat medium, guides the refrigerant discharged from the compressor during the heating operation to heat the heat medium to the heat medium heat exchanger, and from the compressor during the cooling operation to cool the heat medium. and a switching valve for guiding the discharged refrigerant to the air heat exchanger, wherein the temperature of the air around the air heat exchanger is a predetermined value during the heating operation. Control the liquid bypass valve from closed to open when:

A control method for a heat source device according to an aspect of the present disclosure includes a compressor that compresses a refrigerant, a heat medium heat exchanger that exchanges heat between the refrigerant and a heat medium, and an air heat exchanger that exchanges heat between the refrigerant and air. and a first expansion valve provided on the heat medium heat exchanger side, a second expansion valve provided on the air heat exchanger side, and between the heat medium heat exchanger and the first expansion valve between a liquid bypass pipe whose upstream end is connected to and guides the liquid refrigerant to the suction side of the compressor, a liquid bypass valve provided in the liquid bypass pipe, and the first expansion valve and the second expansion valve A receiver that stores a refrigerant, guides the refrigerant discharged from the compressor during the heating operation that heats the heat medium to the heat medium heat exchanger, and the compression during the cooling operation that cools the heat medium a switching valve for guiding the refrigerant discharged from the machine to the air heat exchanger; a switching valve provided in parallel with the first expansion valve, the receiver, and the second expansion valve; A control method for a heat source device comprising parallel refrigerant pipes connected to an air heat exchanger and a third expansion valve provided in the parallel refrigerant pipes, wherein the third expansion valve is operated during the heating operation. The degree of opening of the first expansion valve and/or the second expansion valve is controlled so that the refrigerant flows to the first expansion valve side, the third expansion valve is opened during the cooling operation, and the The degree of opening of the first expansion valve and/or the second expansion valve is controlled so that the refrigerant does not flow to the second expansion valve side.

A control method for a heat source device according to an aspect of the present disclosure includes a compressor that compresses a refrigerant, a heat medium heat exchanger that exchanges heat between the refrigerant and a heat medium, and an air heat exchanger that exchanges heat between the refrigerant and air. and a first expansion valve provided on the heat medium heat exchanger side, a second expansion valve provided on the air heat exchanger side, and between the heat medium heat exchanger and the first expansion valve between a liquid bypass pipe whose upstream end is connected to and guides the liquid refrigerant to the suction side of the compressor, a liquid bypass valve provided in the liquid bypass pipe, and the first expansion valve and the second expansion valve A receiver that stores a refrigerant, guides the refrigerant discharged from the compressor during the heating operation that heats the heat medium to the heat medium heat exchanger, and the compression during the cooling operation that cools the heat medium a switching valve for guiding refrigerant discharged from the compressor to the air heat exchanger, wherein the temperature of the refrigerant discharged from the compressor is equal to or less than a predetermined value during the heating operation. The opening degree of the first expansion valve is controlled such that

1 Chiller (heat source machine)
3 compressor 3a housing 3b compression mechanism 4 four-way valve (switching valve)
5 Water heat exchanger (heat medium heat exchanger)
6 First expansion valve 7 Receiver 8 Second expansion valve 9 Air heat exchanger 10 Accumulator 12 Fan 14 Discharge temperature sensor 16 Water pipe 18 Outside air temperature sensor 20 Liquid bypass pipe 22 Liquid bypass valve 30 Parallel refrigerant pipe 32 Third expansion valve

Claims (6)

a compressor that compresses a refrigerant;
a heat medium heat exchanger that exchanges heat between a refrigerant and a heat medium;
an expansion valve that expands the refrigerant;
an air heat exchanger that exchanges heat between refrigerant and air;
a liquid bypass pipe whose upstream end is connected between the heat medium heat exchanger and the expansion valve and guides the liquid refrigerant to the suction side of the compressor;
with
The expansion valve includes a first expansion valve provided on the heat medium heat exchanger side and a second expansion valve provided on the air heat exchanger side,
the upstream end of the liquid bypass pipe is connected between the heat medium heat exchanger and the first expansion valve;
A receiver for storing refrigerant is provided between the first expansion valve and the second expansion valve,
During the heating operation for heating the heat medium, the refrigerant discharged from the compressor is guided to the heat medium heat exchanger, and during the cooling operation for cooling the heat medium, the refrigerant discharged from the compressor is transferred to the air heat exchange. A switching valve that leads to the vessel,
a parallel refrigerant pipe provided in parallel with the first expansion valve, the receiver, and the second expansion valve and connecting the heat medium heat exchanger and the air heat exchanger;
a third expansion valve provided in the parallel refrigerant pipe;
During the heating operation, the third expansion valve is closed, the degree of opening of the first expansion valve and/or the second expansion valve is controlled so that the refrigerant flows to the first expansion valve side, and during the cooling operation and a control unit for controlling the degree of opening of the first expansion valve and/or the second expansion valve so that the third expansion valve is opened and the refrigerant does not flow to the second expansion valve side. machine. A liquid bypass valve provided in the liquid bypass pipe,
2. The liquid bypass valve according to claim 1, wherein the controller controls the liquid bypass valve from closed to open during the heating operation and when the air temperature around the air heat exchanger is equal to or lower than a predetermined value. heat source machine. A liquid bypass valve provided in the liquid bypass pipe and serving as an on-off valve,
The heat source equipment according to claim 1, wherein the control unit controls the degree of opening of the first expansion valve so that the temperature of the refrigerant discharged from the compressor is equal to or less than a predetermined value during the heating operation. a compressor that compresses a refrigerant;
a heat medium heat exchanger that exchanges heat between a refrigerant and a heat medium ;
an air heat exchanger that exchanges heat between refrigerant and air;
a first expansion valve provided on the heat medium heat exchanger side;
a second expansion valve provided on the side of the air heat exchanger;
a liquid bypass pipe whose upstream end is connected between the heat medium heat exchanger and the first expansion valve and guides the liquid refrigerant to the suction side of the compressor ;
a receiver provided between the first expansion valve and the second expansion valve for storing refrigerant;
During the heating operation for heating the heat medium, the refrigerant discharged from the compressor is guided to the heat medium heat exchanger, and during the cooling operation for cooling the heat medium, the refrigerant discharged from the compressor is transferred to the air heat exchange. A switching valve that leads to the vessel,
a parallel refrigerant pipe provided in parallel with the first expansion valve, the receiver, and the second expansion valve and connecting the heat medium heat exchanger and the air heat exchanger;
a third expansion valve provided in the parallel refrigerant pipe;
A control method for a heat source machine comprising
During the heating operation, the third expansion valve is closed, the degree of opening of the first expansion valve and/or the second expansion valve is controlled so that the refrigerant flows to the first expansion valve side, and during the cooling operation 3. A control method for a heat source equipment, wherein the opening of the first expansion valve and/or the second expansion valve is controlled such that the third expansion valve is opened and the refrigerant does not flow to the second expansion valve side. A liquid bypass valve provided in the liquid bypass pipe,
5. The control of the heat source equipment according to claim 4, wherein the liquid bypass valve is controlled from closed to open during the heating operation and when the air temperature around the air heat exchanger is equal to or lower than a predetermined value. Method. A liquid bypass valve provided in the liquid bypass pipe,
5. The control method of the heat source equipment according to claim 4, further comprising controlling the degree of opening of the first expansion valve so that the temperature of the refrigerant discharged from the compressor is equal to or less than a predetermined value during the heating operation.

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