WO2023012899A1

WO2023012899A1 - Refrigeration cycle device

Info

Publication number: WO2023012899A1
Application number: PCT/JP2021/028789
Authority: WO
Inventors: 悟梁池
Original assignee: 三菱電機株式会社
Priority date: 2021-08-03
Filing date: 2021-08-03
Publication date: 2023-02-09
Also published as: CN117693655A; JPWO2023012899A1

Abstract

This refrigeration cycle device has: a first heat exchanger having a plurality of heat transfer pipes and a first header for distributing refrigerant to the plurality of heat transfer pipes; a gas-liquid separator for separating refrigerant flowing into the first heat exchanger into a gas refrigerant and a liquid refrigerant; a gas bypass circuit for allowing the gas refrigerant to flow into the first header from the gas-liquid separator; a liquid bypass circuit for allowing the liquid refrigerant to flow into the first header from the gas-liquid separator; and, a bypass valve provided to at least one of the gas bypass circuit and the liquid bypass circuit. With reference to the circulation direction of the liquid refrigerant in the first header, the gas bypass circuit is connected to the first header farther downstream in the circulation direction of the liquid refrigerant relative to the position at which the liquid bypass circuit is connected to the first header.

Description

refrigeration cycle equipment

The present disclosure relates to a refrigeration cycle device having a refrigerant circuit.

As an example of a conventional heat exchanger, a heat exchanger has been proposed that has a gas-liquid separation mechanism that separates the refrigerant into a gas refrigerant and a liquid refrigerant before the refrigerant flows into the heat exchanger (see, for example, Patent Document 1).

The heat exchanger disclosed in Patent Document 1 has a plurality of heat transfer tubes, a first header, a second header, a gas-liquid separation mechanism, a first outlet pipe, and a second outlet pipe. The first header and the second header have internal spaces extending in a specific horizontal direction. The second header is arranged above the first header. The gas-liquid separation mechanism is arranged above the second header. A first inlet at one of the ends of the first header in a specific direction is connected to the gas-liquid separation mechanism via a first outlet pipe, and a second inlet at the other end is a second outlet pipe. It is connected to the gas-liquid separation mechanism via.

In the heat exchanger disclosed in Patent Document 1, the gas refrigerant flows into the first header through the first outlet pipe from the gas-liquid separation mechanism, and the liquid refrigerant flows into the first header through the second outlet pipe. It is configured to flow in from the separation mechanism.

JP 2017-223386 A

In the heat exchanger disclosed in Patent Document 1, the flow rate of each of the gas refrigerant and the liquid refrigerant flowing into the first header depends on the state of separation of the gas-liquid two phases in the gas-liquid separation mechanism. Therefore, for example, if the liquid refrigerant flows unevenly in some of the plurality of heat transfer tubes, the refrigerant cannot be distributed appropriately to the plurality of heat transfer tubes. In this case, the heat exchange efficiency becomes low.

The present disclosure has been made to solve the above problems, and provides a refrigeration cycle device that improves heat exchange efficiency.

A refrigeration cycle device according to the present disclosure includes a first heat exchanger having a plurality of heat transfer tubes and a first header for distributing refrigerant flowing through the refrigerant piping to the plurality of heat transfer tubes; A gas-liquid separator that separates the refrigerant flowing into the heat exchanger into a gas refrigerant and a liquid refrigerant, and the gas-liquid separator and the first header are connected to separate the gas refrigerant from the gas-liquid separator into the first header. a gas bypass circuit that flows into one header; a liquid bypass circuit that connects the gas-liquid separator and the first header and causes the liquid refrigerant to flow from the gas-liquid separator into the first header; a bypass valve provided in at least one of the gas bypass circuit and the liquid bypass circuit; As such, the liquid bypass circuit is connected to the first header downstream in the flow direction from the position where the liquid bypass circuit is connected to the first header.

According to the present disclosure, in the first header that functions as a distributor of the first heat exchanger, gas refrigerant is blown up from the downstream side of the liquid refrigerant, and the flow rate of liquid refrigerant or gas refrigerant flowing into the first header is regulated by the bypass valve. Therefore, the liquid refrigerant flowing into the first header diffuses within the first header, and the gas-liquid two-phase refrigerant is evenly distributed to the plurality of heat transfer tubes. As a result, the heat exchange efficiency of the first heat exchanger is improved.

1 is a refrigerant circuit diagram showing one configuration example of a refrigeration cycle apparatus according to Embodiment 1. FIG. FIG. 2 is a schematic side view for explaining the configuration of the first heat exchanger shown in FIG. 1; FIG. 2 is a schematic diagram showing one configuration example of the gas bypass valve shown in FIG. 1 ; FIG. 2 is a state diagram of a refrigeration cycle by the refrigeration cycle device shown in FIG. 1; 4 is a refrigerant circuit diagram showing another configuration example of the refrigeration cycle apparatus according to Embodiment 1. FIG. 3 is a schematic side view showing another installation example of the first heat exchanger shown in FIG. 2. FIG. FIG. 7 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle apparatus according to Embodiment 2; FIG. 8 is a state diagram of a refrigeration cycle by the refrigeration cycle device shown in FIG. 7; FIG. 11 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle apparatus according to Embodiment 3; FIG. 10 is a state diagram of a refrigeration cycle by the refrigeration cycle device shown in FIG. 9; FIG. 11 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle apparatus according to Embodiment 4; 12 is a functional block diagram showing a configuration example of a controller shown in FIG. 11; FIG. FIG. 13 is a hardware configuration diagram showing a configuration example of a controller shown in FIG. 12; 13 is a hardware configuration diagram showing another configuration example of the controller shown in FIG. 12; FIG. 13 is a flow chart showing the procedure of a control method executed by the controller shown in FIG. 12;

Embodiment 1.
The configuration of the refrigeration cycle apparatus of Embodiment 1 will be described. FIG. 1 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle apparatus according to Embodiment 1. FIG. As shown in FIG. 1 , the refrigeration cycle device 1 has a compressor 2 , a first heat exchanger 3 , a gas-liquid separator 4 , an expansion valve 5 and a second heat exchanger 6 . In the refrigerant pipe 16 connecting the compressor 2, the first heat exchanger 3, the expansion valve 5 and the second heat exchanger 6, the gas-liquid separator 4 is connected to the first heat exchanger 3 and the expansion valve 5. is set between Compressor 2 , first heat exchanger 3 , expansion valve 5 and second heat exchanger 6 constitute refrigerant circuit 10 in which refrigerant circulates.

The compressor 2 compresses and discharges the sucked refrigerant. Compressor 2 is, for example, a reciprocating compressor and a rotary compressor. The expansion valve 5 is an expansion device that decompresses and expands the refrigerant. The expansion valve 5 is, for example, a thermal expansion valve. Thermostatic expansion valves are of two types: external pressure equalizing expansion valves and internal pressure equalizing expansion valves. When the expansion valve 5 is an external pressure inhibiting type expansion valve, a temperature sensing tube (not shown) provided in the refrigerant pipe 16 between the first heat exchanger 3 and the compressor 2 and A pressure equalizing pipe (not shown) connected to the refrigerant pipe 16 on the compressor 2 side is connected to the expansion valve 5 . The expansion valve 5 detects the pressure difference between the pressure of a substance (a substance with the same characteristics as the refrigerant) enclosed in a temperature sensing cylinder (not shown) and the pressure of the refrigerant input through a pressure equalizing pipe (not shown). Automatically adjusts the opening according to

FIG. 2 is a schematic side view for explaining the configuration of the first heat exchanger shown in FIG. In FIG. 2, arrows of three axes (X-axis, Y-axis and Z-axis) defining directions are displayed for convenience of explanation. Let the direction opposite to the Z-axis arrow be the direction of gravity.

The first heat exchanger 3 has a plurality of heat transfer tubes 11, a first header 12 and a second header 13. A plurality of heat transfer tubes 11 extend parallel to the Y-axis. Each of the first header 12 and the second header 13 has a cylindrical or cuboid configuration extending parallel to the Z-axis. As shown in FIG. 2 , the first heat exchanger 3 is provided with a plurality of radiation fins 17 between the first header 12 and the second header 13 . Each radiation fin 17 is arranged at equal intervals in the direction parallel to the Y-axis with the adjacent radiation fins 17 . Each radiation fin 17 has a plate-like configuration parallel to the XZ plane. A plurality of heat transfer tubes 11 pass through a plurality of radiation fins 17 . In the first heat exchanger 3 shown in FIG. 1, the radiation fins 17 shown in FIG. 2 are omitted.

In Embodiment 1, the configuration in which the first heat exchanger 3 has radiation fins 17 was described with reference to FIG. It may be a heat exchanger.

The first header 12 serves as a distributor that distributes the refrigerant flowing from the gas-liquid separator 4 through the refrigerant pipes 16 to the plurality of heat transfer tubes 11 . The second header 13 serves as a combiner that joins the refrigerant flowing through the plurality of heat transfer tubes 11 and flows out to the refrigerant suction port of the compressor 2 . Each of the first header 12 and the second header 13 has a hollow structure for accumulating the refrigerant branched to the plurality of heat transfer tubes 11 or the refrigerant flowing from the plurality of heat transfer tubes 11 . The plurality of heat transfer tubes 11 are connected to the first header 12 at different heights with respect to the direction of gravity. The second heat exchanger 6 has the same configuration as the first heat exchanger 3, and detailed description thereof will be omitted.

The gas-liquid separator 4 separates the refrigerant flowing into the first heat exchanger 3 from the expansion valve 5 into gas refrigerant and liquid refrigerant. The gas-liquid separator 4 and the first header 12 are connected via a gas bypass circuit 7 that allows gas refrigerant to flow from the gas-liquid separator 4 into the first header 12 . Also, the gas-liquid separator 4 and the first header 12 are connected via a liquid bypass circuit 8 that allows the liquid refrigerant to flow from the gas-liquid separator 4 to the first header 12 .

The liquid bypass circuit 8 is connected to the top of the first header 12 . A gas bypass circuit 7 is connected to the lower portion of the first header 12 . In Embodiment 1, the first header 12 has a structure in which gas refrigerant flows in from the lower portion of the first header 12 so as to blow up the liquid refrigerant flowing in from the upper portion of the first header 12 . A gas bypass valve 14 is provided in the gas bypass circuit 7 . The gas bypass valve 14 adjusts the degree of opening of the flow path resistance corresponding to the flow rate of the liquid refrigerant flowing into the first header 12 so that the flow rate of the gas refrigerant required for blowing up can be obtained. The configuration of the gas bypass valve 14 will be specifically described below.

When the flow rate of the liquid refrigerant flowing into the first header 12 is small, the liquid refrigerant flows through the first header 12 more than the upper side (Z-axis arrow direction in FIG. 2) of the first header 12 due to the effect of gravity. It tends to accumulate in the lower side (opposite direction of the Z-axis arrow in FIG. 2), and it becomes difficult to flow into the upper heat transfer tube 11 among the plurality of heat transfer tubes 11 . Therefore, among the plurality of heat transfer tubes 11, more liquid refrigerant flows in the heat transfer tubes 11 on the lower side, and the amount of liquid refrigerant flowing in the heat transfer tubes 11 on the upper side decreases. In this case, the opening degree of the gas bypass valve 14 is increased so that the amount of gas refrigerant blowing up the liquid refrigerant increases. This makes it easier for the liquid refrigerant to flow through the heat transfer tubes 11 on the upper side among the plurality of heat transfer tubes 11 .

On the other hand, when the flow rate of the liquid refrigerant flowing into the first header 12 is large, the flow rate of the liquid refrigerant is large even under the influence of gravity. It becomes easier to flow not only into the heat transfer tubes 11 on the opposite side of the arrow) but also into the heat transfer tubes 11 on the upper side (the direction of the Z-axis arrow in FIG. 2). Further, in the first embodiment, even if the flow rate of the liquid refrigerant flowing into the first header 12 from the upper side of the first header 12 is large, the liquid refrigerant flows from the lower side of the first header 12. It is blown up by the gas refrigerant and diffuses inside the first header 12 . Therefore, it becomes easier for the liquid refrigerant to flow evenly through the plurality of heat transfer tubes 11 .

As described above, the gas bypass valve 14 adjusts the flow ratio of the liquid refrigerant and gas refrigerant flowing into the first header 12 based on the flow rate of the liquid refrigerant flowing into the first header 12 . The gas bypass valve 14 is, for example, a valve that keeps the refrigerant pressure difference between the refrigerant inlet and outlet constant. Considering that the flow rate ratio between the liquid refrigerant flowing out of the gas-liquid separator 4 and the gas refrigerant flowing out of the gas-liquid separator 4 is constant, when the flow rate of the liquid refrigerant flowing into the first header 12 is large, the first The flow rate of gas refrigerant flowing into the header 12 also increases. If the gas bypass valve 14 is a valve that maintains a constant refrigerant pressure difference between the refrigerant inlet and the refrigerant outlet, the pressure difference between the refrigerant inlet and the refrigerant outlet decreases when the flow rate of the gas refrigerant is low. The bypass valve 14 automatically increases the degree of opening in order to keep the pressure difference of the refrigerant constant.

A specific configuration example of the gas bypass valve 14 is a valve that operates on the same principle as a thermal expansion valve. The gas bypass valve 14 has a regulating valve (not shown) such as a diaphragm that detects the refrigerant pressure difference between the refrigerant inlet and outlet, and adjusts the degree of opening according to the operation of the regulating valve. In this case, there is no need to provide a special configuration such as a controller for controlling the degree of opening of the gas bypass valve 14 .

An example of the configuration of the gas bypass valve 14 will be described. FIG. 3 is a schematic diagram showing one configuration example of the gas bypass valve shown in FIG. The gas bypass valve 14 is connected to the gas-liquid separator 4 via the gas bypass circuit 7 on the refrigerant inlet 51 side, and is connected to the first header 12 via the gas bypass circuit 7 on the refrigerant outlet 52 side. The gas bypass valve 14 includes a diaphragm chamber 53, a pressure chamber 55 provided with a spring 54, an orifice plate provided with an orifice 56 for circulating the refrigerant from the refrigerant inlet 51 to the refrigerant outlet 52, and an opening of the orifice 56. and a needle 57 for adjusting the power.

The diaphragm chamber 53 is connected via a first pressure equalizing pipe 61 to the gas bypass circuit 7 on the refrigerant inlet 51 side. The pressure chamber 55 is connected to the gas bypass circuit 7 on the refrigerant outlet 52 side via a second pressure equalizing pipe 62 . The diaphragm chamber 53 has a diaphragm 53a on the boundary surface with the pressure chamber 55, and a shaft 58 is attached to the diaphragm 53a. A needle 57 is attached to the end of the shaft 58 opposite to the diaphragm 53a. The diaphragm 53 a moves along the axial direction of the shaft 58 due to the refrigerant pressure difference ΔP between the refrigerant inlet 51 and the refrigerant outlet 52 and the elastic force of the spring 54 . The opening of the orifice 56 is adjusted by moving the needle 57 as the diaphragm 53 a moves in the axial direction of the shaft 58 . As a result, the flow rate of the refrigerant flowing through the orifice 56 is adjusted, and the refrigerant pressure difference ΔP is kept constant.

Next, the operation of the refrigeration cycle of the refrigeration cycle device 1 shown in FIG. 1 will be described. A case where the first heat exchanger 3 functions as an evaporator will be described. FIG. 4 is a state diagram of a refrigerating cycle by the refrigerating cycle apparatus shown in FIG. In the state diagram shown in FIG. 4, the horizontal axis is the specific enthalpy h [kJ/kg] and the vertical axis is the pressure P [MPa]. P1 to P8 shown in FIG. 4 indicate states of the refrigerant at positions p1 to p8 in the refrigerant circuit 10 shown in FIG.

The compressor 2 sucks gas refrigerant, compresses the sucked gas refrigerant, and discharges it (see position p1 in FIG. 4). The gas refrigerant discharged from the compressor 2 is condensed by exchanging heat with air in the second heat exchanger 6, becomes liquid refrigerant, and flows out of the second heat exchanger 6 (position p2 in FIG. 4). reference). The liquid refrigerant that has flowed out of the second heat exchanger 6 is decompressed by the expansion valve 5 and becomes a gas-liquid two-phase refrigerant (see position p3 in FIG. 4). When the gas-liquid two-phase refrigerant flows into the gas-liquid separator 4, it is separated into a liquid refrigerant (see position p4 in FIG. 4) and a gas refrigerant (see position p5 in FIG. 4).

The liquid refrigerant reaches the first header 12 from the gas-liquid separator 4 via the liquid bypass circuit 8 . The liquid refrigerant that has reached the first header 12 flows into the first header 12 from the top of the first header 12 . The gas refrigerant separated by the gas-liquid separator 4 flows from the gas-liquid separator 4 through the gas bypass circuit 7 . The gas refrigerant flowing through the gas bypass circuit 7 is depressurized by the gas bypass valve 14, and after the flow rate is adjusted, flows into the first header 12 from the lower part of the first header 12 (see position p6 in FIG. 4). .

At position p6 shown in FIG. 4, when the flow rate of the refrigerant flowing into the gas bypass valve 14 is low, the gas bypass valve 14 increases the degree of opening to increase the flow rate of the gas refrigerant. When the flow rate of the refrigerant flowing into the gas bypass valve 14 is large, the gas bypass valve 14 reduces the degree of opening to reduce the flow rate of the gas refrigerant.

The gas refrigerant flowing into the first header 12 from the bottom of the first header 12 is mixed with the liquid refrigerant while blowing up the liquid refrigerant flowing into the first header 12 from the top of the first header 12 (Fig. 4 position p7). The mixed gas-liquid two-phase refrigerant is divided into a plurality of heat transfer tubes 11 . The gas-liquid two-phase refrigerant flowing through each heat transfer tube 11 exchanges heat with the air, evaporates and gasifies, and then joins at the second header 13 . The gas refrigerant that joins at the second header 13 flows into the compressor 2 from the refrigerant suction port of the compressor 2 (see position p8 in FIG. 4).

In this way, an appropriate amount of gas refrigerant is blown up from the lower portion of the first header 12 in accordance with the flow rate of liquid refrigerant flowing from the upper portion of the first header 12 of the first heat exchanger 3 . Therefore, the flow rate of the refrigerant in each heat transfer tube 11 of the plurality of heat transfer tubes 11 can be made uniform.

In the first embodiment, the gas bypass circuit 7 is provided with a bypass valve that maintains a constant flow rate ratio between the liquid refrigerant and the gas refrigerant flowing from the gas-liquid separator 4 into the first header 12. , a bypass valve may be provided on the liquid bypass circuit 8 side. 5 is a refrigerant circuit diagram showing another configuration example of the refrigeration cycle apparatus according to Embodiment 1. FIG. As shown in FIG. 5, when the liquid bypass circuit 8 is provided with the liquid bypass valve 15, the liquid bypass valve 15 reduces the degree of opening when the flow rate of the liquid refrigerant flowing into the liquid bypass circuit 8 is large. When the flow rate of the liquid refrigerant flowing into the circuit 8 is small, the opening is increased.

1 shows a configuration in which the liquid bypass circuit 8 is connected to the upper portion of the first header 12, and the gas bypass circuit 7 is connected to the lower portion of the first header 12. These bypass circuits The connection positions are not limited to those shown in FIG. The gas bypass circuit 7 is connected downstream of the position where the liquid bypass circuit 8 is connected to the first header 12 with respect to the direction of liquid refrigerant flow in the first header 12 . It is good if there is In this case as well, the liquid refrigerant flowing into the first header 12 is blown up by the gas refrigerant in the direction of the Z-axis arrow shown in FIG.

Also, in Embodiment 1, the first header 12 may be arranged so as to extend parallel to the Y-axis shown in FIG. FIG. 6 is a schematic side view showing another installation example of the first heat exchanger shown in FIG. FIG. 6 shows a configuration in which the first heat exchanger 3 is installed such that the direction in which the first header 12 extends is parallel to the ground. In the installation example shown in FIG. 6, among the plurality of heat transfer tubes 11, the heat transfer tube closest to the Y-axis arrow is called the first heat transfer tube 21, and the heat transfer tube closest to the Y-axis arrow is called the second heat transfer tube. These are called heat transfer tubes 22 .

In the case of the installation example shown in FIG. 6, the liquid refrigerant flows through the liquid bypass circuit 8 to the first header 12. Due to the inertial force when the liquid refrigerant flows down, the liquid refrigerant flows through the first header 12 as indicated by the dashed arrow. The direction indicated makes it easier to flow. Therefore, when the amount of refrigerant flowing into the first header 12 is small, the refrigerant flows more easily toward the second heat transfer tube 22 than the first heat transfer tube 21, but the gas refrigerant flowing through the gas bypass valve 14 is blown up to the first heat transfer tube 21 side. Thus, the direction in which the first header 12 extends may be parallel to the ground. Moreover, in the installation example shown in FIG. 6, the first heat exchanger 3 may be inclined with respect to the ground.

Furthermore, in Embodiment 1, the expansion valve 5 may be an electronic expansion valve, and the compressor 2 may be an inverter compressor whose capacity can be changed. When the expansion valve 5 is an electronic expansion valve and the compressor 2 is an inverter compressor, the refrigeration cycle apparatus 1 is provided with a controller (not shown) for controlling the opening degree of the expansion valve 5 and the operating frequency of the compressor 2. may have been

The refrigeration cycle apparatus 1 of Embodiment 1 has a first heat exchanger 3, a gas-liquid separator 4, a gas bypass circuit 7, and a liquid bypass circuit 8. The first heat exchanger 3 has a plurality of heat transfer tubes 11 and a first header 12 that distributes the refrigerant flowing through the refrigerant pipes 16 to the plurality of heat transfer tubes 11 . The gas-liquid separator separates the refrigerant flowing into the first heat exchanger 3 into gas refrigerant and liquid refrigerant. The gas bypass circuit 7 connects the gas-liquid separator 4 and the first header 12 and causes the gas refrigerant to flow from the gas-liquid separator 4 into the first header 12 . The liquid bypass circuit 8 connects the gas-liquid separator 4 and the first header 12 and causes the liquid refrigerant to flow from the gas-liquid separator 4 to the first header 12 . At least one of the gas bypass circuit 7 and the liquid bypass circuit 8 is provided with a bypass valve. The bypass valve adjusts the degree of opening according to the flow rate of refrigerant flowing into one of the bypass circuits. The bypass valve is either gas bypass valve 14 or liquid bypass valve 15 . The gas bypass circuit 7 is located downstream of the position where the liquid bypass circuit 8 is connected to the first header 12 in the liquid refrigerant circulation direction, with the liquid refrigerant circulation direction in the first header 12 as a reference. is connected to the header 12 of the

According to the first embodiment, when the bypass valve is the gas bypass valve 14 , when the flow rate of the gas refrigerant flowing into the gas bypass circuit 7 is small, the gas bypass valve 14 is closed in the first header 12 with liquid refrigerant. The opening is adjusted so that the flow rate of the gas refrigerant blown out from the downstream side of is increased. When the opening degree of the gas bypass valve 14 increases, the liquid refrigerant is lifted upward of the first header 12 by the gas refrigerant blown up from the downstream side. As a result, the liquid refrigerant flows more easily into the heat transfer tubes 11 on the upper side (in the direction of the Z-axis arrow in FIG. 2), and the gas-liquid two-phase refrigerant that has flowed into the first header 12 is evenly divided into the plurality of heat transfer tubes 11. .

On the other hand, when the flow rate of the gas refrigerant flowing into the gas bypass circuit 7 is large, the liquid refrigerant flows not only in the heat transfer tubes 11 on the lower side (opposite direction of the Z-axis arrow in FIG. 2) among the plurality of heat transfer tubes 11, It also becomes easier to flow into the heat transfer tubes 11 on the upper side (in the direction of the Z-axis arrow in FIG. 2). In addition, the liquid refrigerant is blown up from the downstream side by the gas refrigerant flowing through the gas bypass valve 14 and is easily diffused in the first header 12 . As a result, the gas-liquid two-phase refrigerant that has flowed into the first header 12 is evenly divided into the plurality of heat transfer tubes 11 .

Further, in the first embodiment, when the bypass valve is the liquid bypass valve 15, when the flow rate of the liquid refrigerant flowing into the liquid bypass circuit 8 is small, the liquid bypass valve 15 is configured to prevent the liquid flowing into the first header 12 from flowing into the first header 12. Adjust the opening so that the flow rate of the refrigerant increases. This makes it easier for the liquid refrigerant to accumulate in the lower side of the first header 12 (opposite direction of the Z-axis arrow in FIG. 2) than in the upper side of the first header 12 (in the direction of the Z-axis arrow in FIG. 2). can be suppressed. In addition, when the flow rate of the liquid refrigerant is small, the liquid refrigerant tends to accumulate in the lower side of the first header 12 , but is blown upward in the first header 12 by the gas refrigerant. Liquid refrigerant can easily flow into the heat transfer tubes 11 above the first header 12 . As a result, the gas-liquid two-phase refrigerant that has flowed into the first header 12 is evenly divided into the plurality of heat transfer tubes 11 .

On the other hand, when the flow rate of the liquid refrigerant flowing into the liquid bypass circuit 8 is large, not only the heat transfer tubes 11 on the lower side (opposite direction of the Z-axis arrow in FIG. 2) among the plurality of heat transfer tubes 11 (Z-axis arrow direction)), the liquid bypass valve 15 is fully opened. Even if the flow rate of the liquid refrigerant flowing into the first header 12 from the upper side of the first header 12 is large, the liquid refrigerant is blown up by the gas refrigerant from the lower side of the first header 12, and the liquid refrigerant flows into the first header. is easily diffused within the header 12 of the As a result, the gas-liquid two-phase refrigerant that has flowed into the first header 12 is evenly divided into the plurality of heat transfer tubes 11 .

When the flow rate of the liquid refrigerant flowing into the liquid bypass circuit 8 is too large, the liquid bypass valve 15 is configured to adjust the degree of opening so that the flow rate of the liquid refrigerant flowing into the first header 12 decreases. good too. If the flow rate of the liquid refrigerant flowing into the liquid bypass circuit 8 is too high, the momentum of the liquid refrigerant flowing into the first header 12 becomes too strong, and the liquid refrigerant tends to flow into some of the heat transfer tubes 11. is. In this case, by reducing the degree of opening of the liquid bypass valve 15 , the flow rate of the liquid refrigerant flowing into the first header 12 becomes appropriate, and the liquid refrigerant is easily divided into the plurality of heat transfer tubes 11 evenly. As a result, the gas-liquid two-phase refrigerant that has flowed into the first header 12 is evenly divided into the plurality of heat transfer tubes 11 .

Thus, in the first header 12 functioning as a distributor of the first heat exchanger 3, the gas refrigerant is blown up from the downstream side of the liquid refrigerant. Then, the flow rate of liquid refrigerant or gas refrigerant flowing into the first header 12 is adjusted by the gas bypass valve 14 or the liquid bypass valve 15 . Therefore, the liquid refrigerant flowing into the first header 12 diffuses within the first header 12 , and the gas-liquid two-phase refrigerant is evenly distributed to the plurality of heat transfer tubes 11 . As a result, the heat exchange efficiency of the first heat exchanger 3 is improved.

Embodiment 2.
The refrigeration cycle apparatus of Embodiment 2 has a configuration in which bypass valves are provided in both the gas bypass circuit and the liquid bypass circuit. In the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the refrigeration cycle apparatus of Embodiment 2 will be described. FIG. 7 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle apparatus according to Embodiment 2. FIG. As shown in FIG. 7, the refrigerating cycle apparatus 1a of Embodiment 2 is provided with a liquid bypass valve 15 in the liquid bypass circuit 8 in addition to the configuration shown in FIG.

The liquid bypass valve 15 is a valve that increases the pressure difference between the gas-liquid separator 4 and the first header 12 . The liquid bypass valve 15 is, for example, a pressure regulating valve that makes the pressure difference between the gas-liquid separator 4 and the first header 12 greater than a predetermined pressure. By increasing the pressure difference between the gas-liquid separator 4 and the first header 12, the force of the gas refrigerant blown up into the first header 12 from the gas bypass circuit 7 can be increased.

Next, the operation of the refrigeration cycle of the refrigeration cycle device 1a shown in FIG. 7 will be described. A case where the first heat exchanger 3 functions as an evaporator will be described. FIG. 8 is a state diagram of the refrigeration cycle by the refrigeration cycle device shown in FIG. In the state diagram shown in FIG. 8, the horizontal axis is the specific enthalpy h [kJ/kg] and the vertical axis is the pressure P [MPa]. P1 to P9 shown in FIG. 8 indicate states of the refrigerant at positions p1 to p9 in the refrigerant circuit 10 shown in FIG.

The compressor 2 sucks gas refrigerant, compresses the sucked gas refrigerant, and discharges it (see position p1 in FIG. 8). The gas refrigerant discharged from the compressor 2 is condensed by exchanging heat with air in the second heat exchanger 6, becomes liquid refrigerant, and flows out of the second heat exchanger 6 (position p2 in FIG. 8). reference). The liquid refrigerant that has flowed out of the second heat exchanger 6 is decompressed by the expansion valve 5 and becomes a gas-liquid two-phase refrigerant (see position p3 in FIG. 8). When the gas-liquid two-phase refrigerant flows into the gas-liquid separator 4, it is separated into a liquid refrigerant (see position p4 in FIG. 8) and a gas refrigerant (see position p5 in FIG. 8).

The liquid refrigerant flows from the gas-liquid separator 4 through the liquid bypass circuit 8 . The liquid refrigerant flowing through the liquid bypass circuit 8 is depressurized by the liquid bypass valve 15, and after the flow rate is adjusted, flows into the first header 12 from the upper portion of the first header 12 (see position p6 in FIG. 8). . On the other hand, the gas refrigerant separated by the gas-liquid separator 4 flows from the gas-liquid separator 4 through the gas bypass circuit 7 . The gas refrigerant flowing through the gas bypass circuit 7 is decompressed by the gas bypass valve 14, and after the flow rate is adjusted, flows into the first header 12 from the lower part of the first header 12 (see position p7 in FIG. 8). .

The gas refrigerant flowing into the first header 12 from the bottom of the first header 12 is mixed with the liquid refrigerant while blowing up the liquid refrigerant flowing into the first header 12 from the top of the first header 12 (Fig. 8 position p8). The mixed gas-liquid two-phase refrigerant is divided into a plurality of heat transfer tubes 11 . The gas-liquid two-phase refrigerant flowing through each heat transfer tube 11 exchanges heat with the air, evaporates and gasifies, and then joins at the second header 13 . The gas refrigerant merged at the second header 13 flows into the compressor 2 from the refrigerant suction port of the compressor 2 (see position p9 in FIG. 8).

The liquid bypass valve 15 increases the pressure difference between the inside of the gas-liquid separator 4 and the inside of the first header 12 . Therefore, compared to the first embodiment, at the position p7 shown in FIG. 8, the momentum of the gas refrigerant blown out from the downstream side of the liquid refrigerant flowing into the first header 12 to the liquid refrigerant increases.

In the refrigeration cycle apparatus 1a of Embodiment 2, a liquid bypass valve 15 is provided in the liquid bypass circuit 8, and the liquid bypass valve 15 is a valve that increases the pressure difference between the gas-liquid separator 4 and the first header 12. be. According to the second embodiment, the liquid refrigerant can be blown up by the gas refrigerant, so when the flow rate of the refrigerant is small, the liquid refrigerant can reach more upward in the first header 12. .

Also, in the gas bypass circuit, when the pressure difference between the refrigerant inlet and outlet of the gas bypass valve is small, the capacity coefficient (Cv value) required to circulate the same flow rate of refrigerant increases. In contrast, in Embodiment 2, the liquid bypass valve 15 increases the pressure difference between the inside of the gas-liquid separator 4 and the inside of the first header 12 . Therefore, in the gas bypass circuit 7, the pressure difference before and after the gas bypass valve 14 increases, and the Cv value required for the gas bypass valve 14 can be lowered. As a result, the gas bypass valve 14 can be downsized.

Embodiment 3.
The refrigeration cycle apparatus of Embodiment 3 has a configuration in which a four-way valve for switching the direction of flow of the refrigerant in the refrigerant circuit is provided in the refrigerant circuit. In Embodiment 3, the same components as those described in

Embodiments

1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. Further, in the third embodiment, a configuration in which a four-way valve is added to the refrigeration cycle device 1a of the second embodiment will be described. may

The configuration of the refrigeration cycle apparatus of Embodiment 3 will be described. FIG. 9 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle apparatus according to Embodiment 3. As shown in FIG. As shown in FIG. 9, the refrigeration cycle apparatus 1b of Embodiment 3 has a configuration in which a four-way valve 9 is added to the configuration shown in FIG.

The four-way valve 9 allows the refrigerant discharged from the compressor 2 to flow in the first flow direction from the compressor 2 to the first heat exchanger 3 or from the compressor 2 to the second heat exchange direction. The second direction of flow, which is the direction of flow to the vessel 6, is set. When the flow direction of the refrigerant discharged from the compressor 2 is set to the first flow direction, the first heat exchanger 3 functions as a condenser and the second heat exchanger 6 functions as an evaporator. . When the flow direction of the refrigerant discharged from the compressor 2 is set to the second flow direction, the first heat exchanger 3 functions as an evaporator and the second heat exchanger 6 functions as a condenser. .

The liquid bypass valve 15 is open when the first heat exchanger 3 functions as an evaporator, as in the second embodiment, but is closed when the first heat exchanger 3 functions as a condenser. It is a configuration that becomes a state. When the first heat exchanger 3 functions as an evaporator, the gas bypass valve 14 is opened to adjust the gas flow rate as in the first and second embodiments. When functioning as a vessel, it is configured to be in a fully open state. In the third embodiment, the gas bypass circuit 7 is connected to the first header 12 at a position lower than the liquid bypass circuit 8 with respect to the height relative to the direction of gravity. When the first heat exchanger 3 functions as a condenser and the gas bypass valve 14 is fully opened, the liquid refrigerant flowing from the heat transfer tubes 11 into the first header 12 flows through the gas bypass circuit 7. Smooth flow to the gas-liquid separator 4 is facilitated.

Next, the operation of the refrigeration cycle of the refrigeration cycle device 1b shown in FIG. 9 will be described. Embodiment 3 describes a case where the first heat exchanger 3 functions as a condenser. Since the operation of the refrigeration cycle when the first heat exchanger 3 functions as an evaporator is the same as the operation described in Embodiment 2, detailed description thereof will be omitted.

FIG. 10 is a state diagram of the refrigeration cycle by the refrigeration cycle device shown in FIG. In the state diagram shown in FIG. 10, the horizontal axis is the specific enthalpy h [kJ/kg] and the vertical axis is the pressure P [MPa]. Positions p1, p2, p5, and p8 to p10 shown in FIG. 10 indicate states of refrigerant at representative positions among positions p1 to p10 in the refrigerant circuit 10 shown in FIG.

The compressor 2 sucks gas refrigerant, compresses the sucked gas refrigerant, and discharges it (see position p1 in FIG. 10). Gas refrigerant discharged from the compressor 2 flows through the four-way valve 9 toward the second header 13 (see position p9 in FIG. 10). The gas refrigerant that has flowed into the second header 13 is divided into a plurality of heat transfer tubes 11 . In each heat transfer tube 11 of the plurality of heat transfer tubes 11, the gas refrigerant exchanges heat with the air and is liquefied. The refrigerant liquefied in each heat transfer tube 11 of the plurality of heat transfer tubes 11 joins the first header 12 (see position p8 in FIG. 10).

The liquid refrigerant that has flowed into the first header 12 from the plurality of heat transfer tubes 11 flows to the lower side of the first header 12 due to its own weight. Since the gas bypass valve 14 is in the fully open state, the liquid refrigerant that has flowed to the lower portion of the first header 12 does not accumulate in the lower portion of the first header 12 and passes through the gas bypass circuit 7 to the gas-liquid separator 4. (see position p5 in FIG. 10). Therefore, accumulation of the liquid refrigerant in the lower portion of the first header 12 is suppressed. Among the plurality of heat transfer tubes 11, the liquid refrigerant flowing through the lower heat transfer tubes 11 does not stay in the lower part of the first header 12, so the liquid refrigerant smoothly flows out of the heat transfer tubes 11 and bypasses the gas. It can flow into the gas-liquid separator 4 via the circuit 7 .

When the liquid refrigerant flows from the gas-liquid separator 4 into the expansion valve 5, it is decompressed by the expansion valve 5 and becomes a gas-liquid two-phase refrigerant (see position p2 in FIG. 10). The gas-liquid two-phase refrigerant flows into the second heat exchanger 6 . In the second heat exchanger 6 , the gas-liquid two-phase refrigerant exchanges heat with air to evaporate and gasify, and then flows out of the second heat exchanger 6 . The gas refrigerant that has flowed out of the second heat exchanger 6 flows into the compressor 2 from the refrigerant suction port of the compressor 2 (see position p10 in FIG. 10).

The refrigeration cycle device 1b of Embodiment 3 has a four-way valve 9 that sets the flow direction of the refrigerant in the refrigerant circuit 10 to the first flow direction or the second flow direction. The gas bypass valve 14 is configured to be fully opened when the flow direction of the refrigerant is set to the second flow direction by the four-way valve 9 .

When the refrigerant circulation direction in the refrigerant circuit is the first circulation direction in which the first heat exchanger functions as a condenser, the condensed liquid refrigerant accumulates in the lower portion of the first header. If the liquid refrigerant accumulates in the lower portion of the first header, the refrigerant outlet of the heat transfer tube to the first header will be blocked by the liquid refrigerant. In this case, the flow of the refrigerant in the heat transfer tubes under the first header is deteriorated, and the heat exchange efficiency of the first heat exchanger is lowered. On the other hand, according to the third embodiment, when the flow direction of the refrigerant is the first flow direction, the gas bypass circuit 7 provided in the gas bypass circuit 7 connected to the lower side of the first header 12 Bypass valve 14 is fully opened. Therefore, the liquid refrigerant can easily flow from the lower portion of the first header 12 to the gas-liquid separator 4 via the gas bypass circuit 7, and the accumulation of the liquid refrigerant in the lower portion of the first header 12 can be suppressed. As a result, the refrigerant can easily flow through the heat transfer tubes 11 on the lower side of the first heat exchanger 3, and the heat exchange efficiency of the first heat exchanger 3 is improved.

Embodiment 4.
The refrigeration cycle apparatus of Embodiment 4 controls the degree of opening of the bypass valve according to the temperature of the refrigerant flowing through the heat transfer tubes. In the fourth embodiment, the same reference numerals are assigned to the same configurations as those described in the first to third embodiments, and detailed description thereof will be omitted. Further, although the fourth embodiment will be described based on the refrigeration cycle apparatus of the third embodiment, the fourth embodiment may be applied to the refrigeration cycle apparatus of the first or second embodiment.

The configuration of the refrigeration cycle apparatus of Embodiment 4 will be described. 11 is a refrigerant circuit diagram showing a configuration example of a refrigeration cycle apparatus according to Embodiment 4. FIG. A refrigeration cycle apparatus 1c shown in FIG. 11 has a configuration in which a first temperature sensor 31 and a second temperature sensor 32 for detecting the temperature of the refrigerant, and a controller 40 are added to the configuration shown in FIG. The first temperature sensor 31 and the second temperature sensor 32 are, for example, thermistors. Each of the first temperature sensor 31, the second temperature sensor 32, the gas bypass valve 14 and the liquid bypass valve 15 is connected to the controller 40 via a signal line (not shown).

The first temperature sensor 31 is the first heat transfer tube, which is the highest heat transfer tube among the plurality of heat transfer tubes 11 with respect to the height based on the direction of gravity (opposite to the Z-axis arrow) shown in FIG. It is provided on the heat tube 21 . The second temperature sensor 32 is provided on the second heat transfer tube 22, which is the lowest heat transfer tube among the plurality of heat transfer tubes 11 with respect to the direction of gravity.

FIG. 12 is a functional block diagram showing one configuration example of the controller shown in FIG. Controller 40 is, for example, a microcomputer. The controller 40 has determination means 42 and valve control means 43 . The determination means 42 calculates the temperature difference Td between the detection value of the first temperature sensor 31 and the detection value of the second temperature sensor 32 . The determination means 42 determines whether or not the temperature difference Td is greater than a predetermined threshold value Tth, and transmits information on the determination result to the valve control means 43 .

When the temperature difference Td is greater than the threshold value Tth, the valve control means 43 adjusts the opening degree of at least one of the gas bypass valve 14 and the liquid bypass valve 15 so that the temperature difference Td becomes equal to or less than the threshold value Tth. do. A specific example of a method for adjusting the degree of opening of the bypass valve by the valve control means 43 will be described below.

When the heat exchanger functions as an evaporator, the temperature of the refrigerant increases when the flow rate of the refrigerant flowing through the heat transfer tubes is low. For example, when the first heat exchanger 3 functions as an evaporator, if the flow rate of the refrigerant flowing through the second heat transfer tubes 22 is less than the flow rate of the refrigerant flowing through the first heat transfer tubes 21, The detected value of the second temperature sensor 32 becomes larger than the detected value of the first temperature sensor 31 . When the temperature difference Td between the detection value of the first temperature sensor 31 and the detection value of the second temperature sensor 32 becomes larger than the threshold value Tth, the valve control means 43 reduces the opening degree of the gas bypass valve 14 . As a result, the amount of gas refrigerant blowing out is reduced, the liquid refrigerant tends to flow down to the lower side of the first header 12, and the flow rate of the refrigerant flowing through the second heat transfer tubes 22 increases. Further, the valve control means 43 may increase the opening degree of the liquid bypass valve 15 . In this case, the flow rate of the liquid refrigerant increases, the flow rate of the gas refrigerant increases from the lower side of the first header 12 against the blowout, and the flow rate of the refrigerant flowing through the second heat transfer tubes 22 increases. Furthermore, the valve control means 43 may reduce the opening degree of the gas bypass valve 14 and increase the opening degree of the liquid bypass valve 15 . In either case, the flow rate of the refrigerant flowing through the plurality of heat transfer tubes 11 becomes uniform.

On the other hand, when the heat exchanger functions as a condenser, the temperature of the refrigerant decreases when the flow rate of the refrigerant flowing through the heat transfer tubes is low. For example, when the first heat exchanger 3 functions as a condenser, if the flow rate of the refrigerant flowing through the first heat transfer tube 21 is less than the flow rate of the refrigerant flowing through the second heat transfer tube 22, The detected value of the first temperature sensor 31 becomes smaller than the detected value of the second temperature sensor 32 . When the temperature difference Td between the detection value of the first temperature sensor 31 and the detection value of the second temperature sensor 32 becomes larger than the threshold value Tth, the valve control means 43 increases the opening degree of the gas bypass valve 14 . As a result, as described in Embodiment 3, the refrigerant flowing through the second heat transfer tube 22 side flows more smoothly, and the flow rate of the refrigerant on the second heat transfer tube 22 side can be increased. . As a result, the flow rate of the refrigerant flowing through the plurality of heat transfer tubes 11 becomes uniform.

In the fourth embodiment, the first heat transfer tube 21 is provided with the first temperature sensor 31 and the second heat transfer tube 22 is provided with the second temperature sensor 32. Any one of the heat transfer tubes may be provided with a temperature sensor. For example, if a heat transfer tube having a relatively low flow rate of refrigerant among the plurality of heat transfer tubes 11 is known in advance, a temperature sensor may be provided for the heat transfer tube having a low flow rate of refrigerant. In this case, the valve control means 43 adjusts the opening degree of the gas bypass valve 14 or the liquid bypass valve 15 so that the detection value of the temperature sensor falls within a predetermined range.

Here, an example of the hardware configuration of the controller 40 shown in FIG. 12 will be described. 13 is a hardware configuration diagram showing a configuration example of the controller shown in FIG. 12. FIG. When various functions of the controller 40 are executed by dedicated hardware, the controller 40 shown in FIG. 12 is configured with a processing circuit 80 as shown in FIG. Each function of the determination means 42 and the valve control means 43 shown in FIG. 12 is implemented by the processing circuit 80 .

When each function is performed by hardware, the processing circuit 80 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate). Array), or a combination thereof. Each of the functions of the determination means 42 and the valve control means 43 may be realized by the processing circuit 80 . Further, the function of each means of the determination means 42 and the valve control means 43 may be realized by one processing circuit 80 .

An example of another hardware configuration of the controller 40 shown in FIG. 12 will also be described. 14 is a hardware configuration diagram showing another configuration example of the controller shown in FIG. 12. FIG. When various functions of the controller 40 are executed by software, the controller 40 shown in FIG. 12 is composed of a processor 81 such as a CPU (Central Processing Unit) and a memory 82 as shown in FIG. Each function of the determination means 42 and the valve control means 43 is implemented by the processor 81 and the memory 82 . FIG. 14 shows that processor 81 and memory 82 are connected via bus 83 . The memory 82 stores the threshold Tth.

When each function is executed by software, the functions of the determination means 42 and the valve control means 43 are realized by software, firmware, or a combination of software and firmware. Software and firmware are written as programs and stored in memory 82 . The processor 81 implements the functions of each means by reading and executing the programs stored in the memory 82 .

As the memory 82, for example, non-volatile semiconductor memories such as ROM (Read Only Memory), flash memory, EPROM (Erasable and Programmable ROM) and EEPROM (Electrically Erasable and Programmable ROM) are used. As the memory 82, a volatile semiconductor memory of RAM (Random Access Memory) may be used. Furthermore, as the memory 82, removable recording media such as magnetic disks, flexible disks, optical disks, CDs (Compact Discs), MDs (Mini Discs) and DVDs (Digital Versatile Discs) may be used.

Next, the operation of the refrigeration cycle device 1c of Embodiment 4 will be described. 15 is a flow chart showing the procedure of a control method executed by the controller shown in FIG. 12. FIG. Here, a case where the first heat exchanger 3 functions as an evaporator will be described. The controller 40 operates according to the flow shown in FIG. 15 at regular intervals.

The determination means 42 acquires detection values from the first temperature sensor 31 and the second temperature sensor 32 (step S101). The determination means 42 calculates the temperature difference Td between the detection value of the first temperature sensor 31 and the detection value of the second temperature sensor 32 . Then, the determination means 42 determines whether or not the temperature difference Td is greater than the threshold value Tth (step S102). When the temperature difference Td is equal to or less than the threshold value Tth as a result of the determination in step S102, the controller 40 ends the process.

On the other hand, if the result of determination in step S102 is that the temperature difference Td is greater than the threshold value Tth, the determination means 42 transmits information on the determination result to the valve control means 43. When the valve control means 43 receives information indicating that the temperature difference Td is greater than the threshold value Tth from the determination means 42, the valve control means 43 adjusts the opening degree of the gas bypass valve 14 or the liquid bypass valve 15 so that the temperature difference Td becomes equal to or less than the threshold value Tth. Adjust (step S103).

Note that when the first temperature sensor 31 is provided on the first heat transfer tube 21 but the second temperature sensor 32 is not provided on the second heat transfer tube 22, in the flow shown in FIG. 40 operates as follows. When the first heat exchanger 3 functions as a condenser, the determination means 42 acquires a detection value from the first temperature sensor 31 in step S101. In step S102, the determination means 42 determines whether the detected value of the first temperature sensor 31 is within a predetermined first temperature range. If the detected value of the first temperature sensor 31 is not within the first temperature range, the valve control means 43 adjusts the opening degree of the gas bypass valve 14 or the liquid bypass valve 15 in step S103. For example, when the detection value of the first temperature sensor 31 is lower than the first temperature range in the determination of step S102, it is considered that the flow rate of the refrigerant flowing into the first heat transfer tube 21 is small. In this case, the valve control means 43 increases the opening degree of the gas bypass valve 14 . Thereby, the flow rate of the refrigerant flowing through the first heat transfer tubes 21 can be increased.

Further, when the first temperature sensor 31 is not provided on the first heat transfer tube 21 but the second temperature sensor 32 is provided on the second heat transfer tube 22, in the flow shown in FIG. 40 operates as follows. When the first heat exchanger 3 functions as an evaporator, the determination means 42 acquires a detection value from the second temperature sensor 32 in step S101. In step S102, the determination means 42 determines whether or not the detected value of the second temperature sensor 32 is within a predetermined second temperature range. If the detected value of the second temperature sensor 32 is not within the second temperature range, the valve control means 43 adjusts the opening degree of the gas bypass valve 14 or the liquid bypass valve 15 in step S103. For example, when the detection value of the second temperature sensor 32 is larger than the second temperature range in the determination of step S102, it is considered that the flow rate of the refrigerant flowing into the second heat transfer tube 22 is small. In this case, the valve control means 43 reduces the opening degree of the gas bypass valve 14 or increases the opening degree of the liquid bypass valve 15 . Thereby, the flow rate of the refrigerant flowing through the second heat transfer tubes 22 can be increased.

Further, in the fourth embodiment, if the expansion valve 5 is an electronic expansion valve and the compressor 2 is an inverter compressor that can change the capacity, the controller 40 controls the opening degree of the expansion valve 5 and the compressor 2 may control the operating frequency of

The refrigeration cycle apparatus 1c of Embodiment 4 has a temperature sensor provided in at least one of the first heat transfer tube 21 and the second heat transfer tube 22, and a controller 40. Controller 40 adjusts the degree of opening of gas bypass valve 14 or liquid bypass valve 15 so that the detected value of the temperature sensor falls within a predetermined range.

According to the fourth embodiment, gas bypass valve 14 or liquid bypass valve 15 is adjusted so that the detected value of the temperature sensor provided in first heat transfer tube 21 or second heat transfer tube 22 is within a predetermined range. is adjusted, the refrigerant flows evenly through the heat transfer tubes 11 . Therefore, the heat exchange efficiency of the first heat exchanger 3 is improved.

Further, in Embodiment 4, the first heat transfer tube 21 may be provided with the first temperature sensor 31 and the second heat transfer tube 22 may be provided with the second temperature sensor 32 . In this case, the controller 40 operates the gas bypass valve 14 or the liquid bypass valve 15 so that the temperature difference Td between the detection value of the first temperature sensor 31 and the detection value of the second temperature sensor 32 is equal to or less than the threshold value Tth. You can adjust the opening. The flow rate of the refrigerant branched to the plurality of heat transfer tubes 11 of the first heat exchanger 3 can be accurately estimated, and the heat exchange efficiency of the first heat exchanger 3 is further improved.

1, 1a to 1c refrigeration cycle device, 2 compressor, 3 first heat exchanger, 4 gas-liquid separator, 5 expansion valve, 6 second heat exchanger, 7 gas bypass circuit, 8 liquid bypass circuit, 9 Four-way valve 10 Refrigerant circuit 11 Heat transfer tube 12 First header 13 Second header 14 Gas bypass valve 15 Liquid bypass valve 16 Refrigerant piping 17 Radiation fin 21 First heat transfer tube 22 Second 2 heat transfer tubes, 31 first temperature sensor, 32 second temperature sensor, 40 controller, 42 determination means, 43 valve control means, 51 refrigerant inlet, 52 refrigerant outlet, 53 diaphragm chamber, 53a diaphragm, 54 spring , 55 pressure chamber, 56 orifice, 57 needle, 58 shaft, 61 first pressure equalization pipe, 62 second pressure equalization pipe, 80 processing circuit, 81 processor, 82 memory, 83 bus.

Claims

a first heat exchanger having a plurality of heat transfer tubes and a first header for distributing refrigerant flowing through refrigerant piping to the plurality of heat transfer tubes;
a gas-liquid separator that separates the refrigerant flowing into the first heat exchanger into a gas refrigerant and a liquid refrigerant;
a gas bypass circuit that connects the gas-liquid separator and the first header and causes the gas refrigerant to flow from the gas-liquid separator into the first header;
a liquid bypass circuit that connects the gas-liquid separator and the first header and causes the liquid refrigerant to flow from the gas-liquid separator into the first header;
a bypass valve provided in at least one of the gas bypass circuit and the liquid bypass circuit;
The gas bypass circuit is located downstream of the position where the liquid refrigerant is connected to the first header in the direction of flow, with respect to the direction of flow of the liquid refrigerant in the first header. connected to the header of the
Refrigeration cycle equipment.
The bypass valve is a valve that maintains a constant pressure difference of the refrigerant between an inflow port and an outflow port of the refrigerant to the bypass valve.
The refrigeration cycle apparatus according to claim 1.
The bypass valve includes a gas bypass valve provided in the gas bypass circuit and a liquid bypass valve provided in the liquid bypass circuit,
The refrigeration cycle apparatus according to claim 1 or 2.
The liquid bypass valve is a valve that increases the pressure difference between the gas-liquid separator and the first header.
The refrigeration cycle device according to claim 3.
the plurality of heat transfer tubes are connected to positions with different heights relative to the first header with respect to the direction of gravity;
The gas bypass circuit is connected to the first header at a position lower than the position at which the liquid bypass circuit is connected to the first header.
The refrigeration cycle apparatus according to any one of claims 1 to 4.
a compressor for compressing and discharging the refrigerant;
a second heat exchanger for heat-exchanging the refrigerant discharged from the compressor with air;
an expansion valve for expanding the refrigerant flowing out of the second heat exchanger and flowing out the expanded refrigerant to the gas-liquid separator;
Regarding the flow direction of the refrigerant discharged from the compressor, a first flow direction that is a flow direction from the compressor to the first heat exchanger or a flow direction from the compressor to the second heat exchanger a four-way valve that is set in a second flow direction that is the direction of
The first heat exchanger distributes the refrigerant flowing in from the four-way valve to the plurality of heat transfer tubes when the flow direction of the refrigerant is set to the first flow direction by the four-way valve. has a header,
The bypass valve is provided in the gas bypass circuit, and is fully opened when the flow direction of the refrigerant is set to the second flow direction by the four-way valve.
The refrigeration cycle apparatus according to claim 5.
a temperature sensor that detects the temperature of the refrigerant;
a controller that adjusts the degree of opening of the bypass valve so that the detected value of the temperature sensor falls within a predetermined range;
the plurality of heat transfer tubes are connected to positions with different heights relative to the first header with respect to the direction of gravity;
The temperature sensor is
provided in at least one of the first heat transfer tube, which is the highest heat transfer tube among the plurality of heat transfer tubes, and the second heat transfer tube, which is the lowest heat transfer tube. ,
The refrigeration cycle apparatus according to claim 1 or 2.
As the temperature sensors, a first temperature sensor provided in the first heat transfer tube and a second temperature sensor provided in the second heat transfer tube,
The controller is
adjusting the degree of opening of the bypass valve so that the temperature difference between the detected value of the first temperature sensor and the detected value of the second temperature sensor is equal to or less than a predetermined threshold;
The refrigeration cycle apparatus according to claim 7.