WO2016051606A1 - Air conditioning device - Google Patents

Abstract

An air conditioning device 1 is provided with a refrigerant circuit 60 that circulates a refrigerant, and an outdoor expansion valve 30 is connected to indoor expansion valves 31a, 31b through a fluid pipe 61, which is a portion of refrigerant piping. The refrigerant circuit 60 can perform an air conditioning operation in which an outdoor heat exchanger 20 functions as a condenser and indoor heat exchangers 40a, 40b function as evaporators. During the air conditioning operation, the outdoor expansion valve 30 puts the refrigerant, which is flowing into the fluid pipe 61, into a biphase state, with R32 being used as the refrigerant. When the inner diameter of the fluid pipe 61 is D[m] and the length of the fluid pipe 61 is L[m], the inner diameter D is in the range of 13.88×10^-3≤D≤17.05×10^-3, and the inner diameter D and the length L satisfy a relationship of L≤1.15×10³×D+1.2.

Description

Air conditioner

The present invention relates to an air conditioner.

Patent Document 1 describes a refrigeration cycle apparatus. This refrigeration cycle apparatus has a configuration in which a compressor, a heat source machine side heat exchanger, a first expansion device, a liquid side connection pipe, a second expansion device, a use side heat exchanger, and a gas side connection pipe are sequentially connected. is doing. The refrigerant used for the refrigeration cycle is R32. Outer diameter of the liquid side connecting pipe and the gas side connecting pipe is a (D 0 _-1) / 8 inches (here, connection pipe outer diameter in the case of using the "D _0/8 inches" refrigerant R410A) . The range of D ₀ is “2 ≦ D ₀ ≦ 4” in the liquid side connection pipe and “3 ≦ D ₀ ≦ 8” in the gas side connection pipe. This document describes that, according to the above configuration, a refrigeration cycle apparatus capable of reducing the amount of refrigerant filled compared to a refrigeration cycle apparatus using R410A can be obtained.

JP 2013-200090 A

However, the refrigeration cycle apparatus described in Patent Document 1 has a problem in that the amount of refrigerant in the liquid side connection pipe cannot always be reduced sufficiently.

The present invention has been made to solve the above-described problems, and an object thereof is to provide an air conditioner that can further reduce the amount of refrigerant.

In the air conditioner according to the present invention, a compressor, a first heat exchanger, a first expansion valve, a second expansion valve, and a second heat exchanger are connected via a refrigerant pipe, and a refrigerant is contained therein. A refrigerant circuit that circulates, and the first expansion valve and the second expansion valve are connected via a liquid pipe that is a part of the refrigerant pipe; A cooling operation in which one heat exchanger functions as a condenser and the second heat exchanger functions as an evaporator is possible, and the first expansion valve flows into the liquid pipe in the cooling operation. When the refrigerant is in a two-phase state, R32 is used as the refrigerant, the inner diameter of the liquid pipe is D [m], and the length of the liquid pipe is L [m]. The range of the inner diameter D is 13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ , and the inner diameter D and the length L Satisfies the relationship L ≦ 1.15 × 10 ³ × D + 1.2.

According to the present invention, the refrigerant in the liquid pipe is two-phased in the cooling operation, so that a high refrigerant amount reduction effect can be obtained. Therefore, according to this invention, the refrigerant | coolant amount of an air conditioning apparatus can be reduced more.

It is a refrigerant circuit diagram which shows schematic structure of the air conditioning apparatus 1 which concerns on Embodiment 1 of this invention. FIG. 6 is a ph diagram showing the state of refrigerant during cooling operation in the refrigerant circuit 60 of the air-conditioning apparatus 1 according to Embodiment 1 of the present invention. [Fig. 6] Fig. 6 is a ph diagram showing a refrigerant state during heating operation in the refrigerant circuit 60 of the air-conditioning apparatus 1 according to Embodiment 1 of the present invention. It is a figure which shows an example of the piping diameter of the refrigerant | coolant piping for every rated capacity of the air conditioning apparatus 1, and a refrigerant | coolant flow rate. It is a figure which shows an example of the piping diameter of a refrigerant | coolant piping, thickness, and an internal diameter. It is the graph which compared the refrigerant | coolant amount ratio in the case of 72.8kW <Q with the liquid pipe thinning technique and the liquid pipe two-phase technology. It is the graph which compared the filling refrigerant | coolant amount ratio in the case of 44.8kW <Q <= 72.8kW with the liquid pipe thinning technique and the liquid pipe two-phase technology. It is the graph which compared the filling refrigerant | coolant amount ratio in the case of 33.6kW <Q <= 44.8kW with the liquid pipe thinning technique and the liquid pipe two-phase technology. In the liquid pipe two-phase technology when R32 is used as the refrigerant, the region where the refrigerant amount reduction effect higher than that of the liquid tube thinning technology is obtained is defined by the inner diameter D of the liquid pipe 61 and the length L of the liquid pipe 61. It is a graph shown by relationship. In the liquid pipe two-phase technology when R32 is used as the refrigerant, a region in which the effect of reducing the refrigerant amount higher than the liquid tube thinning technology is obtained is the ratio of the length L to the inner diameter D of the liquid pipe 61 (L / D ) And the supercooling degree SC at the outlet of the condenser. In the liquid pipe two-phase technology when R410A is used as the refrigerant, the region where the refrigerant amount reduction effect higher than that of the liquid tube thinning technology is obtained can be expressed by the inner diameter D of the liquid pipe 61 and the length L of the liquid pipe 61. It is a graph shown by relationship. In the liquid pipe two-phase technology when R410A is used as the refrigerant, the ratio of the length L to the inner diameter D of the liquid pipe 61 (L / D) is obtained as a region where the refrigerant amount reduction effect is higher than that of the liquid pipe thinning technology. ) And the supercooling degree SC at the outlet of the condenser.

Embodiment 1 FIG.
An air conditioner according to Embodiment 1 of the present invention will be described. FIG. 1 is a refrigerant circuit diagram illustrating a schematic configuration of an air-conditioning apparatus 1 according to the present embodiment. As shown in FIG. 1, the air conditioner 1 has a refrigerant circuit 60 that circulates refrigerant. The refrigerant circuit 60 includes a compressor 10, a four-way valve 11, an outdoor heat exchanger 20 (an example of a first heat exchanger), an outdoor expansion valve 30 (an example of a first expansion valve), and at least one indoor expansion valve 31a. , 31b (an example of a second expansion valve), and at least one indoor heat exchanger 40a, 40b (an example of a second heat exchanger) are connected in an annular shape via a refrigerant pipe. Yes. During the cooling operation, the compressor 10, the outdoor heat exchanger 20, the outdoor expansion valve 30, the indoor expansion valve 31a, and the indoor heat exchanger 40a are connected in an annular shape in this order. Further, during the cooling operation, the compressor 10, the outdoor heat exchanger 20, the outdoor expansion valve 30, the indoor expansion valve 31b, and the indoor heat exchanger 40b are connected in an annular shape in this order. During the heating operation, the refrigerant flow path is switched by the four-way valve 11, and the compressor 10, the indoor heat exchanger 40a, the indoor expansion valve 31a, the outdoor expansion valve 30, and the outdoor heat exchanger 20 are connected in an annular shape in this order. Further, during the heating operation, the compressor 10, the indoor heat exchanger 40b, the indoor expansion valve 31b, the outdoor expansion valve 30, and the outdoor heat exchanger 20 are annularly connected in this order.

In the present embodiment, as the air conditioner 1, a multi air conditioning system for buildings including a plurality of indoor units is illustrated. The air conditioner 1 includes, for example, one outdoor unit 100 installed outdoors, and two indoor units 200a and 200b installed indoors and connected in parallel to the outdoor unit 100, for example. ing. The air conditioner 1 may have two or more outdoor units, or may have only one unit or three or more indoor units.

In the outdoor unit 100, a compressor 10, a four-way valve 11, an outdoor heat exchanger 20, and an outdoor expansion valve 30 are accommodated. Further, the outdoor unit 100 houses an outdoor blower 21 that blows outside air to the outdoor heat exchanger 20.

The indoor unit 200a accommodates an indoor expansion valve 31a and an indoor heat exchanger 40a. The indoor unit 200a houses an indoor blower 41a that blows air to the indoor heat exchanger 40a. Similarly, the indoor unit 200b accommodates an indoor expansion valve 31b, an indoor heat exchanger 40b, and an indoor fan 41b that blows air to the indoor heat exchanger 40b.

Compressor 10 is a fluid machine that compresses sucked low-pressure refrigerant and discharges it as high-pressure refrigerant. The four-way valve 11 switches the flow direction of the refrigerant in the refrigerant circuit 60 between the cooling operation and the heating operation. The outdoor heat exchanger 20 is a heat exchanger that functions as a condenser during cooling operation and functions as an evaporator during heating operation. In the outdoor heat exchanger 20, heat exchange is performed between the refrigerant circulating inside and the air (outside air) blown by the outdoor blower 21. The outdoor expansion valve 30 is an electronic expansion valve (for example, a linear electronic expansion valve) whose opening degree can be adjusted in multiple stages (for example, three stages or more) or continuously under the control of the control unit 300 described later. The outdoor expansion valve 30 decompresses the high-pressure refrigerant into a two-phase refrigerant at least during the cooling operation. The operation of the outdoor expansion valve 30 will be described later.

The indoor expansion valves 31a and 31b are electronic expansion valves (for example, linear electronic expansion valves) whose opening degree can be adjusted in multiple stages (for example, three stages or more) or continuously under the control of the control unit 300 described later. The operation of the indoor expansion valves 31a and 31b will be described later. The indoor heat exchangers 40a and 40b are heat exchangers that function as an evaporator during cooling operation and function as a condenser during heating operation. In the indoor heat exchangers 40a and 40b, heat exchange is performed between the refrigerant circulating in the interior and the air blown by the indoor fans 41a and 41b.

The outdoor unit 100 and the indoor units 200a and 200b are connected via a liquid pipe 61 and a gas pipe 62. The liquid pipe 61 and the gas pipe 62 are part of the refrigerant piping that constitutes the refrigerant circuit 60.

The liquid pipe 61 connects between the outdoor expansion valve 30 of the outdoor unit 100 and the indoor expansion valves 31a and 31b of the indoor units 200a and 200b. The liquid pipe 61 includes a refrigerant pipe 63 inside the outdoor unit 100 that connects between the outdoor expansion valve 30 and the joint part 101 of the outdoor unit 100, and a joint part 101 and joint parts 201a and 201b of the indoor units 200a and 200b. It includes an extension pipe 64 that connects between them, and refrigerant pipes 65a and 65b inside the indoor units 200a and 200b that connect between the joint portions 201a and 201b and the indoor expansion valves 31a and 31b. The liquid pipe 61 circulates liquid refrigerant or two-phase refrigerant (mainly two-phase refrigerant in the present embodiment).

The gas pipe 62 connects between the indoor heat exchangers 40a and 40b of the indoor units 200a and 200b and the four-way valve 11 of the outdoor unit 100. The gas pipe 62 includes refrigerant pipes 66a and 66b inside the indoor units 200a and 200b that connect the indoor heat exchangers 40a and 40b and the joint portions 202a and 202b of the indoor units 200a and 200b, and joint portions 202a and 202b. An extension pipe 67 that connects between the joint portion 102 of the outdoor unit 100 and a refrigerant pipe 68 inside the outdoor unit 100 that connects between the joint portion 102 and the four-way valve 11 are included. The gas pipe 62 circulates a gas refrigerant.

In the refrigerant circuit 60 of this example, a pressure sensor 70 for detecting the pressure (discharge pressure) Pd of the refrigerant discharged from the compressor 10 and the pressure (intake pressure) Ps of the refrigerant sucked into the compressor 10 are provided. A pressure sensor 71 for detecting and a pressure sensor 72 for detecting the pressure (intermediate pressure) Pm of the refrigerant in the liquid pipe 61 are provided. These pressure sensors output detection signals to the control unit 300 described later.

Further, the air conditioner 1 has a control unit 300. The control unit 300 is based on an operation signal from an operation unit operated by a user, detection signals from various sensor groups including pressure sensors 70, 71, 72 and a temperature sensor (not shown), and the like. The entire air conditioner 1 including the expansion valves 31a and 31b is controlled. The control unit 300 includes a microcomputer having a CPU, a ROM, a RAM, an I / O port, and the like. The control unit 300 may be configured by an outdoor unit control unit provided in the outdoor unit 100 and an indoor unit control unit provided in each of the indoor units 200a and 200b and capable of data communication with the outdoor unit control unit. .

In the present embodiment, R32 or R410A is used as the refrigerant circulating in the refrigerant circuit 60.

Next, the operation of the refrigerant circuit 60 of the air conditioner 1 will be described. In order to simplify the description, it is assumed that only one indoor unit 200a among the plurality of indoor units 200a and 200b is operating and the other indoor units 200b are stopped. In this state, the indoor expansion valve 31b of the other indoor unit 200b is controlled to be fully closed, for example.

First, the operation during cooling operation will be described. FIG. 2 is a ph diagram showing the state of the refrigerant during the cooling operation in the refrigerant circuit 60 of the air-conditioning apparatus 1. In FIG. 2 and the ph diagram of FIG. 3 to be described later, symbols of the outdoor expansion valve 30, the liquid pipe 61, and the indoor expansion valve 31a are shown in corresponding portions. In this example, the opening degree of the outdoor expansion valve 30 during the cooling operation is based on the degree of superheat of the refrigerant flowing out of the indoor heat exchanger 40a (evaporator) (the degree of superheat at the evaporator outlet). Control is performed so that the refrigerant flowing out of the refrigerant enters a two-phase state. Moreover, in this example, the opening degree of the indoor expansion valve 31a during the cooling operation is controlled to be fully opened.

The high-temperature and high-pressure gas refrigerant (point A in FIG. 2) discharged from the compressor 10 flows into the outdoor heat exchanger 20 through the four-way valve 11. In the cooling operation, the outdoor heat exchanger 20 functions as a condenser. That is, in the outdoor heat exchanger 20, heat exchange is performed between the refrigerant circulating inside and the air (outside air) blown by the outdoor blower 21, and the condensation heat of the refrigerant is radiated to the blown air. As a result, the refrigerant flowing into the outdoor heat exchanger 20 is condensed and becomes a high-pressure liquid refrigerant (point B in FIG. 2). The high-pressure liquid refrigerant flows into the outdoor expansion valve 30 and is reduced in pressure to become a medium-pressure two-phase refrigerant (point C in FIG. 2). Here, the medium pressure is a pressure that is lower than the high-pressure side pressure (for example, condensation pressure) and higher than the low-pressure side pressure (for example, evaporation pressure) of the refrigeration cycle. The medium-pressure two-phase refrigerant that has flowed out of the outdoor expansion valve 30 passes through the liquid pipe 61 and further passes through the fully-expanded indoor expansion valve 31a. The refrigerant that has passed through the liquid pipe 61 and the indoor expansion valve 31a is depressurized by the pressure loss in the liquid pipe 61 and the indoor expansion valve 31a, and becomes a low-pressure two-phase refrigerant (points D and E in FIG. 2).

The low-pressure two-phase refrigerant that has passed through the fully opened indoor expansion valve 31a flows into the indoor heat exchanger 40a. In the cooling operation, the indoor heat exchanger 40a functions as an evaporator. That is, in the indoor heat exchanger 40a, heat exchange is performed between the refrigerant circulating in the interior and the air (room air) blown by the indoor blower 41a, and the evaporation heat of the refrigerant is absorbed from the blown air. As a result, the refrigerant flowing into the indoor heat exchanger 40a evaporates and becomes a low-pressure gas refrigerant (point F in FIG. 2). Moreover, the air blown by the indoor blower 41a is cooled by the endothermic action of the refrigerant and becomes cold air. The low-pressure gas refrigerant evaporated in the indoor heat exchanger 40a passes through the gas pipe 62 and the four-way valve 11, is decompressed due to pressure loss, and is sucked into the compressor 10 (point G in FIG. 2). The low-pressure gas refrigerant sucked into the compressor 10 is compressed into a high-temperature and high-pressure gas refrigerant (point A in FIG. 2). In the cooling operation, these cycles are repeated. As described above, the medium pressure two-phase refrigerant flows in the liquid pipe 61 in the cooling operation.

Next, the operation during heating operation will be described. During the heating operation, the refrigerant flow path is switched by the four-way valve 11, and the high-temperature and high-pressure refrigerant discharged from the compressor 10 flows into the indoor heat exchanger 40a. FIG. 3 is a ph diagram showing the state of the refrigerant during the heating operation in the refrigerant circuit 60 of the air-conditioning apparatus 1. In this example, the opening degree of the outdoor expansion valve 30 during the heating operation is controlled to be fully open. Moreover, in this example, the opening degree of the indoor expansion valve 31a during the heating operation is based on the degree of supercooling of the refrigerant flowing out of the indoor heat exchanger 40a (condenser) (the degree of supercooling of the condenser outlet). Control is performed so that the refrigerant flowing out of the indoor expansion valve 31a is in a two-phase state.

The high-temperature and high-pressure gas refrigerant (point A in FIG. 3) discharged from the compressor 10 passes through the four-way valve 11 and the gas pipe 62, is depressurized by pressure loss, and flows into the indoor heat exchanger 40a (in FIG. 3). Point B). In the heating operation, the indoor heat exchanger 40a functions as a condenser. That is, in the indoor heat exchanger 40a, heat exchange is performed between the refrigerant circulating in the interior and the air (indoor air) blown by the indoor blower 41a, and the heat of condensation of the refrigerant is radiated to the blown air. As a result, the refrigerant flowing into the indoor heat exchanger 40a condenses and becomes a high-pressure liquid refrigerant (point C in FIG. 3). In addition, the air blown by the indoor blower 41a is heated by the heat dissipation action of the refrigerant and becomes hot air. The high-pressure liquid refrigerant condensed in the indoor heat exchanger 40a flows into the indoor expansion valve 31a and is reduced in pressure to become a medium-pressure two-phase refrigerant (point D in FIG. 3). The medium-pressure two-phase refrigerant that has flowed out of the indoor expansion valve 31a passes through the liquid pipe 61, and further passes through the fully-expanded outdoor expansion valve 30. The refrigerant that has passed through the liquid pipe 61 and the outdoor expansion valve 30 is depressurized due to the pressure loss in the liquid pipe 61 and the outdoor expansion valve 30, and becomes a low-pressure two-phase refrigerant (points E and F in FIG. 3).

The low-pressure two-phase refrigerant that has passed through the fully-expanded outdoor expansion valve 30 flows into the outdoor heat exchanger 20. In the heating operation, the outdoor heat exchanger 20 functions as an evaporator. That is, in the outdoor heat exchanger 20, heat exchange between the refrigerant circulating in the interior and the air (outside air) blown by the outdoor blower 21 is performed, and the heat of evaporation of the refrigerant is absorbed from the blown air. As a result, the refrigerant flowing into the outdoor heat exchanger 20 evaporates and becomes a low-pressure gas refrigerant (point G in FIG. 3). The low-pressure gas refrigerant is sucked into the compressor 10 through the four-way valve 11. The low-pressure gas refrigerant sucked into the compressor 10 is compressed into a high-temperature and high-pressure gas refrigerant (point A in FIG. 3). In the heating operation, these cycles are repeated. As described above, the medium pressure two-phase refrigerant flows in the liquid pipe 61 also in the heating operation.

Next, the pipe diameter of the refrigerant pipe including the liquid pipe 61 and the gas pipe 62 will be described. FIG. 4 is a diagram illustrating an example of the pipe diameter of the refrigerant pipe and the refrigerant flow rate for each rated capacity of the air conditioner 1. In FIG. 4, in order from the top, the rated capacity ([HP] and [kW]) of the air conditioner 1, the pipe diameter (outer diameter) [mm] of the liquid main pipe (for example, the liquid pipe 61), the gas main pipe (for example, The pipe diameter (outer diameter) [mm] of the gas pipe 62), the refrigerant flow rate [kg / h] when R32 is used, and the refrigerant flow rate [kg / h] when R410A is used. As shown in FIG. 4, the relationship between the rated capacity Q of the air conditioner 1 and the pipe diameter of the liquid pipe 61 is, for example, as follows. That is,
The pipe diameter of the liquid pipe 61 when 14.0 kW ≦ Q ≦ 33.6 kW is φ9.52.
The pipe diameter of the liquid pipe 61 in the case of 33.6 kW <Q ≦ 44.8 kW is φ12.70,
The pipe diameter of the liquid pipe 61 in the case of 44.8 kW <Q ≦ 72.8 kW is φ15.88,
The pipe diameter of the liquid pipe 61 in the case of 72.8 kW <Q is φ19.05.

FIG. 5 is a diagram illustrating an example of the pipe diameter [mm], the wall thickness [mm], and the inner diameter D [mm] of the refrigerant pipe. As shown in FIG. 5, the relationship between the pipe diameter of the liquid pipe 61 and the inner diameter D is, for example, as follows. That is,
The inner diameter D of the liquid tube 61 of φ9.52 is 7.92 mm,
The inner diameter D of the liquid pipe 61 of φ12.70 is 11.10 mm,
The inner diameter D of the liquid pipe 61 of φ15.88 is 13.88 mm,
The inner diameter D of the liquid pipe 61 having a diameter of 19.05 is 17.05 mm.

Next, the refrigerant amount reduction effect in the present embodiment will be described. As a technique for reducing the refrigerant amount in the refrigeration cycle, for example, a liquid tube thinning technique and a liquid pipe two-phase technique used in the present embodiment are conceivable. The liquid tube narrowing technique is a technique for reducing the amount of refrigerant to be filled by reducing the volume of the liquid pipe by narrowing the liquid pipe. The liquid pipe two-phase technology is a technique for reducing the amount of refrigerant charged by reducing the density of the refrigerant by setting the refrigerant in the liquid pipe to a two-phase state. Hereinafter, by comparing the liquid tube thinning technology and the liquid tube two-phase technology, the conditions under which a higher refrigerant amount reduction effect can be obtained by the liquid tube two-phase technology will be examined. Since the cooling operation requires a larger amount of refrigerant than the heating operation, the following description assumes the case of the cooling operation.

As a premise, in the liquid tube thinning technique, it is assumed that a pipe that is one size smaller than a normal pipe is used for the liquid pipe 61. Based on this assumption, the ratio of the flow path cross-sectional area of the normal pipe and the flow path cross-sectional area of the one-size thin pipe is taken as the ratio of the amount of refrigerant charged in the liquid pipe. The relationship between the rated capacity Q of the air conditioner using the liquid tube thinning technology and the ratio of the pipe diameter of the liquid pipe 61 and the amount of refrigerant charged in the liquid pipe 61 is as follows, for example. That is,
In the case of 33.6 kW <Q ≦ 44.8 kW, the pipe diameter of the liquid pipe 61 is φ9.52 that is one size smaller than φ12.70, and the ratio of the amount of refrigerant charged in the liquid pipe 61 is 50.9%. .
When 44.8 kW <Q ≦ 72.8 kW, the pipe diameter of the liquid pipe 61 is φ12.70, which is one size smaller than φ15.88, and the ratio of the amount of refrigerant charged in the liquid pipe 61 is 64.0%. .
In the case of 72.8 kW <Q, the pipe diameter of the liquid pipe 61 is φ15.88, which is one size smaller than φ19.05, and the ratio of the charged refrigerant amount in the liquid pipe 61 is 66.3%.
The lower the ratio of the charged refrigerant amount, the higher the effect of reducing the refrigerant amount. Note that the increase in the pressure loss of the liquid pipe 61 due to the narrowing of the pipe is not considered here.

First, the case where the rated capacity Q is 72.8 kW <Q will be described. FIG. 6 is a graph in which the ratio of the amount of refrigerant charged when 72.8 kW <Q is compared between the liquid tube thinning technique and the liquid pipe two-phase technique. The horizontal axis of the graph represents the degree of supercooling SC [K] at the outlet of the condenser, and the vertical axis represents the charged refrigerant amount ratio [%]. Line B represents the ratio of the amount of refrigerant charged by the liquid tube thinning technique, and line A1 represents the ratio of the refrigerant amount charged by the liquid pipe two-phase technique (when the length of the liquid pipe 61 is 5 m). , Line A2 represents the charged refrigerant amount ratio by the liquid pipe two-phase technique (when the length of the liquid pipe 61 is 10 m), and the line A3 represents the liquid pipe two-phase technique (the length of the liquid pipe 61). Represents the ratio of the amount of refrigerant charged in the case of 15 m. In the graph, the area where the refrigerant amount reduction effect higher than that of the liquid tube narrowing technology is obtained is hatched. The pipe diameter of the liquid pipe 61 in the liquid pipe narrowing technique is φ15.88, and the pipe diameter of the liquid pipe 61 in the liquid pipe two-phase technique is φ19.05.

As described above, in the case of 72.8 kW <Q, the amount ratio of the refrigerant charged by the liquid tube thinning technique is 66.3%. As shown in FIG. 6, when the supercooling degree SC at the condenser outlet is 3K or less, the charged refrigerant amount ratio by the liquid tube two-phase technology can be lower than the charged refrigerant amount ratio by the liquid tube thinning technology. I understand that.

Next, the case where the rated capacity Q is 44.8 kW <Q ≦ 72.8 kW will be described. FIG. 7 is a graph in which the ratio of charged refrigerant when 44.8 kW <Q ≦ 72.8 kW is compared between the liquid tube thinning technique and the liquid pipe two-phase technology. The way of viewing the graph is the same as in FIG. The pipe diameter of the liquid pipe 61 in the liquid pipe narrowing technique is φ12.70, and the pipe diameter of the liquid pipe 61 in the liquid pipe two-phase technique is φ15.88.

As described above, in the case of 44.8 kW <Q ≦ 72.8 kW, the charging refrigerant amount ratio by the liquid tube narrowing technique is 64.0%. As shown in FIG. 7, when the degree of supercooling SC at the condenser outlet is about 3K or less, the charged refrigerant amount ratio by the liquid tube two-phase technology becomes lower than the charged refrigerant amount ratio by the liquid tube thinning technology. I know you get.

Next, the case where the rated capacity Q is 33.6 kW <Q ≦ 44.8 kW will be described. FIG. 8 is a graph in which the ratio of the amount of refrigerant charged when 33.6 kW <Q ≦ 44.8 kW is compared between the liquid tube thinning technique and the liquid pipe two-phase technology. The way of viewing the graph is the same as in FIG. The pipe diameter of the liquid pipe 61 in the liquid pipe narrowing technique is φ9.52 and the pipe diameter of the liquid pipe 61 in the liquid pipe two-phase technique is φ12.70.

As described above, in the case of 33.6 kW <Q ≦ 44.8 kW, the charging refrigerant amount ratio by the liquid tube narrowing technique is 50.9%. As shown in FIG. 8, the ratio of the amount of refrigerant charged by the liquid pipe two-phase technology is not limited to the supercooling degree SC at the outlet of the condenser and the length of the liquid pipe 61. It becomes higher than the quantity ratio. That is, in the case of 33.6 kW <Q ≦ 44.8 kW, the liquid pipe two-phase technology cannot provide a higher refrigerant amount reduction effect than the liquid tube thinning technology.

As shown in FIGS. 6 to 8, when the rated capacity Q of the air conditioner 1 is 44.8 kW <Q, when the degree of supercooling SC at the outlet of the condenser is 0K <SC ≦ 3K, By using the phase technology, it is possible to obtain a higher refrigerant amount reduction effect than the liquid tube thinning technology. Here, as shown in FIG. 4, in the capacity range where the rated capacity Q is 44.8 kW <Q, the pipe diameter of the liquid pipe 61 is φ15.88 or more (inner diameter D is 13.88 mm or more), and R32 When R is used, the refrigerant flow rate is larger than 610.0 kg / h, and when R410A is used, the refrigerant flow rate is larger than 905.4 kg / h.

FIG. 9 shows a region in the liquid pipe two-phase technology when R32 is used as the refrigerant in the graph of FIGS. 6 is a graph showing a relationship between an inner diameter D and a length L of a liquid pipe 61. The horizontal axis of the graph represents the inner diameter D [mm] of the liquid pipe 61, and the vertical axis represents the length L [m] of the liquid pipe 61. Lines C1, C2, and C3 represent the relationship between the inner diameter D and the length L when the degree of supercooling SC at the condenser outlet is 0K, 1K, and 2K, respectively. In the graph, the area where the refrigerant amount reduction effect higher than that of the liquid tube narrowing technology is obtained is hatched in the same manner as in FIGS.

In the graph of FIG. 9, the region where the refrigerant amount reduction effect higher than that of the liquid tube narrowing technology is obtained is expressed by the following equations (1) and (2). Here, in the expressions (1) and (2), the unit of the inner diameter D and the length L of the liquid pipe 61 is [m]. In this example, the length L of the liquid pipe 61 is a pipe length between the outdoor expansion valve 30 and the indoor expansion valve 31a (or the indoor expansion valve 31b). That is, in this example, the length L of the liquid pipe 61 is the length of the refrigerant pipe 63 inside the outdoor unit 100 and the length of the extension pipe 64 between the outdoor unit 100 and the indoor unit 200a (or the indoor unit 200b). And the length of the refrigerant pipe 65a inside the indoor unit 200a (or the refrigerant pipe 65b inside the indoor unit 200b). The lower limit of the length L of the liquid pipe 61 is 0 m (L> 0).

[Equation 1]
L ≦ 1.15 × 10 ³ × D + 1.2 (1)

[Equation 2]
13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ (2)

Therefore, by satisfying the conditions of the above formulas (1) and (2), in the liquid pipe two-phase technology when R32 is used as the refrigerant, a higher refrigerant amount reduction effect than in the liquid tube thinning technique can be obtained. . When the plurality of indoor units 200a and 200b are connected in parallel to the outdoor unit 100, it is sufficient that at least one indoor unit satisfies the conditions of the expressions (1) and (2).

FIG. 10 shows a region where a higher refrigerant amount reduction effect can be obtained in the graphs of FIGS. 6 to 8 in the liquid pipe two-phase technology when R32 is used as the refrigerant than in the liquid tube thinning technology. 6 is a graph showing the relationship between the ratio of length L to inner diameter D (L / D) and the degree of supercooling SC at the condenser outlet. The horizontal axis of the graph represents the ratio of the length L [m] to the inner diameter D [m] of the liquid pipe 61 (L / D) [-(dimensionless)], and the vertical axis represents the degree of supercooling at the condenser outlet. SC [K] is represented. Lines E1, E2, and E3 represent the relationship between the ratio (L / D) and the degree of supercooling SC when the pipe diameter of the liquid pipe 61 is φ12.70, φ15.88, and φ19.05, respectively. . In the graph, the area where the refrigerant amount reduction effect higher than that of the liquid tube thinning technique is obtained is hatched as in FIGS.

In the graph of FIG. 10, the region in which the refrigerant amount reduction effect higher than that of the liquid tube thinning technique is obtained is represented by the following formula (3). However, the range of the inner diameter D [m] of the liquid pipe 61 is 13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ . The lower limit of the degree of supercooling SC is 0K (SC> 0). In Expression (3), the magnitude relationship between the numerical value on the left side and the numerical value on the right side is defined without considering the dimension.

[Equation 3]
SC ≦ −0.003 × L / D + 4.0 (3)

Therefore, by satisfying the condition of the above formula (3), in the liquid pipe two-phase technology when R32 is used as the refrigerant, a higher refrigerant amount reduction effect than in the liquid tube thinning technique can be obtained. When the plurality of indoor units 200a and 200b are connected in parallel to the outdoor unit 100, it is sufficient that at least one indoor unit satisfies the condition of the expression (3).

As described above, the air conditioner 1 according to the present embodiment includes the compressor 10, the outdoor heat exchanger 20, the outdoor expansion valve 30, the indoor expansion valves 31a and 31b, and the indoor heat exchangers 40a and 40b as refrigerant pipes. A refrigerant circuit 60 that circulates the refrigerant therein, and the outdoor expansion valve 30 and the indoor expansion valves 31a and 31b are connected via a liquid pipe 61 that is a part of the refrigerant pipe. The refrigerant circuit 60 can perform a cooling operation in which the outdoor heat exchanger 20 functions as a condenser and the indoor heat exchangers 40a and 40b function as an evaporator, and the outdoor expansion valve 30 has a liquid pipe 61 in the cooling operation. The refrigerant flowing into the two-phase state is R32, and the inner diameter of the liquid pipe 61 is D [m] and the length of the liquid pipe 61 is L [m]. The range of the inner diameter D is 13.8 A ^{× 10 -3 ≦ D ≦ 17.05 ×} 10 -3, the inner diameter D and length L, satisfy the relation of ^{L ≦ 1.15 × 10 3 × D} + 1.2.

Further, in the air conditioner 1 according to the present embodiment, the compressor 10, the outdoor heat exchanger 20, the outdoor expansion valve 30, the indoor expansion valves 31a and 31b, and the indoor heat exchangers 40a and 40b are connected via a refrigerant pipe. A refrigerant circuit 60 that circulates the refrigerant therein, and the outdoor expansion valve 30 and the indoor expansion valves 31a and 31b are connected via a liquid pipe 61 that is a part of the refrigerant pipe. 60 can perform a cooling operation in which the outdoor heat exchanger 20 functions as a condenser and the indoor heat exchangers 40a and 40b function as an evaporator, and the outdoor expansion valve 30 is a refrigerant that flows into the liquid pipe 61 in the cooling operation. R32 is used as the refrigerant, the inner diameter of the liquid pipe 61 is set to D [m], the length of the liquid pipe 61 is set to L [m], and the outdoor operation is performed in the cooling operation. Out of heat exchanger 20 When the degree of supercooling of the medium was SC [K], the range of the inner diameter D is ^{13.88 × 10 -3 ≦ D ≦ 17.05} × 10 -3, the inner diameter D, length L and subcooling SC satisfies the relationship SC ≦ −0.003 × L / D + 4.0.

According to these configurations, in the air conditioner 1 in which R32 is used as the refrigerant, the refrigerant in the liquid pipe 61 is two-phased during the cooling operation, thereby providing a higher refrigerant amount reduction effect than the liquid pipe thinning technique. can get. Therefore, according to this Embodiment, the refrigerant | coolant amount of the air conditioning apparatus 1 can be reduced more. Moreover, according to these structures, since the pipe diameter of the liquid pipe 61 can be maintained without being reduced, an increase in the pressure loss of the liquid pipe 61 can be suppressed as compared with the liquid pipe thinning technique. it can.

FIG. 11 shows a region in the liquid pipe two-phase technology where R410A is used as the refrigerant in the graph of FIGS. 6 is a graph showing a relationship between an inner diameter D and a length L of a liquid pipe 61. The way of viewing the graph is the same as in FIG.

In the graph of FIG. 11, the region in which the refrigerant amount reduction effect higher than that of the liquid tube thinning technique is obtained is expressed by the following equations (4) and (5). Here, in the expressions (4) and (5), the unit of the inner diameter D and the length L of the liquid pipe 61 is [m]. The lower limit of the length L of the liquid pipe 61 is 0 m (L> 0).

[Equation 4]
L ≦ 1.00 × 10 ³ × D-3.3 (4)

[Equation 5]
13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ (5)

Therefore, by satisfying the conditions of the above formulas (4) and (5), in the liquid pipe two-phase technology when R410A is used as the refrigerant, a higher refrigerant amount reduction effect than in the liquid tube thinning technique can be obtained. . When the plurality of indoor units 200a and 200b are connected in parallel to the outdoor unit 100, it is sufficient that at least one indoor unit satisfies the conditions of equations (4) and (5).

FIG. 12 shows a region in the liquid pipe two-phase technology where R410A is used as the refrigerant in the graph of FIGS. 6 is a graph showing the relationship between the ratio of length L to inner diameter D (L / D) and the degree of supercooling SC at the condenser outlet. The way of viewing the graph is the same as in FIG.

In the graph of FIG. 12, the region where the refrigerant amount reduction effect higher than that of the liquid tube thinning technique is obtained is expressed by the following equation (6). However, the range of the inner diameter D [m] of the liquid pipe 61 is 13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ . The lower limit of the degree of supercooling SC is 0K (SC> 0). In Expression (6), the magnitude relationship between the numerical value on the left side and the numerical value on the right side is defined without considering the dimension.

[Equation 6]
SC ≦ −0.005 × L / D + 3.7 (6)

Therefore, by satisfying the condition of the above formula (6), in the liquid tube two-phase technology when R410A is used as the refrigerant, a higher refrigerant amount reduction effect than in the liquid tube thinning technology can be obtained. When the plurality of indoor units 200a and 200b are connected in parallel to the outdoor unit 100, it is sufficient that at least one indoor unit satisfies the condition of Expression (6).

As described above, the air conditioner 1 according to the present embodiment includes the compressor 10, the outdoor heat exchanger 20, the outdoor expansion valve 30, the indoor expansion valves 31a and 31b, and the indoor heat exchangers 40a and 40b as refrigerant pipes. A refrigerant circuit 60 that circulates the refrigerant therein, and the outdoor expansion valve 30 and the indoor expansion valves 31a and 31b are connected via a liquid pipe 61 that is a part of the refrigerant pipe. The refrigerant circuit 60 can perform a cooling operation in which the outdoor heat exchanger 20 functions as a condenser and the indoor heat exchangers 40a and 40b function as an evaporator, and the outdoor expansion valve 30 has a liquid pipe 61 in the cooling operation. The refrigerant flowing into the two-phase state is made into a two-phase state, R410A is used as the refrigerant, the inner diameter of the liquid pipe 61 is D [m], and the length of the liquid pipe 61 is L [m]. The range of the inner diameter D is 13 A ^{88 × 10 -3 ≦ D ≦ 17.05} × 10 -3, the inner diameter D and length L, satisfy the relation of ^{L ≦ 1.00 × 10 3 × D} -3.3.

Further, in the air conditioner 1 according to the present embodiment, the compressor 10, the outdoor heat exchanger 20, the outdoor expansion valve 30, the indoor expansion valves 31a and 31b, and the indoor heat exchangers 40a and 40b are connected via a refrigerant pipe. A refrigerant circuit 60 that circulates the refrigerant therein, and the outdoor expansion valve 30 and the indoor expansion valves 31a and 31b are connected via a liquid pipe 61 that is a part of the refrigerant pipe. 60 can perform a cooling operation in which the outdoor heat exchanger 20 functions as a condenser and the indoor heat exchangers 40a and 40b function as an evaporator, and the outdoor expansion valve 30 is a refrigerant that flows into the liquid pipe 61 in the cooling operation. R410A is used as the refrigerant, the inner diameter of the liquid pipe 61 is set to D [m], the length of the liquid pipe 61 is set to L [m], and the outdoor operation is performed in the cooling operation. Outflow from heat exchanger 20 That when the degree of subcooling of the refrigerant was SC [K], the range of the inner diameter D is ^{13.88 × 10 -3 ≦ D ≦ 17.05} × 10 -3, the inner diameter D, length L and supercooling The degree SC satisfies the relationship SC ≦ −0.005 × L / D + 3.7.

According to these configurations, in the air-conditioning apparatus 1 in which R410A is used as the refrigerant, the refrigerant in the liquid pipe 61 is two-phased during the cooling operation, thereby providing a higher refrigerant amount reduction effect than the liquid pipe thinning technique. can get. Therefore, according to this Embodiment, the refrigerant | coolant amount of the air conditioning apparatus 1 can be reduced more. Moreover, according to these structures, since the pipe diameter of the liquid pipe 61 can be maintained without being reduced, an increase in the pressure loss of the liquid pipe 61 can be suppressed as compared with the liquid pipe thinning technique. it can.

Other embodiments.
The present invention is not limited to the above embodiment, and various modifications can be made.
For example, the operation of the outdoor expansion valve 30 and the indoor expansion valve 31a is not limited to the operation of the above embodiment. For example, during the cooling operation, the opening degree of the outdoor expansion valve 30 is controlled based on the differential pressure (Pd−Pm) between the discharge pressure Pd and the intermediate pressure Pm, and the opening degree of the indoor expansion valve 31a is determined based on the outlet of the evaporator. It may be controlled based on the degree of superheat. Further, during the heating operation, the opening degree of the outdoor expansion valve 30 is controlled based on the differential pressure (Pm−Ps) between the intermediate pressure Pm and the suction pressure Ps, and the opening degree of the indoor expansion valve 31a is determined based on the outlet of the condenser. Control may be performed based on the degree of supercooling. By controlling in this way, the refrigerant density in the liquid pipe 61 can be made constant regardless of the operating state of the air conditioner 1. Therefore, it is possible to suppress the performance degradation due to the increase / decrease of the refrigerant amount in the liquid pipe 61.

In the above embodiment, an air conditioner capable of cooling operation and heating operation has been described as an example. However, the present invention can also be applied to an air conditioner capable of only cooling operation.

In the above embodiment, the outdoor unit 100 and the indoor units 200a and 200b are connected via the two extension pipes 64 and 67. However, the outdoor unit 100 and the indoor units 200a and 200b are connected to each other. May be connected via three or more extension pipes.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 10, Compressor, 11 Four-way valve, 20 Outdoor heat exchanger, 21 Outdoor fan, 30 Outdoor expansion valve, 31a, 31b Indoor expansion valve, 40a, 40b Indoor heat exchanger, 41a, 41b Indoor fan, 60 refrigerant circuit, 61 liquid pipe, 62 gas pipe, 63, 65a, 65b, 66a, 66b, 68 refrigerant pipe, 64, 67 extension pipe, 70, 71, 72 pressure sensor, 100 outdoor unit, 101, 102, 201a, 201b, 202a, 202b joint part, 200a, 200b indoor unit, 300 control part.

Claims (6)

A compressor, a first heat exchanger, a first expansion valve, a second expansion valve, and a second heat exchanger are connected via a refrigerant pipe, and include a refrigerant circuit that circulates a refrigerant therein,
The first expansion valve and the second expansion valve are connected via a liquid pipe that is a part of the refrigerant pipe,
The refrigerant circuit is capable of cooling operation in which the first heat exchanger functions as a condenser and the second heat exchanger functions as an evaporator,
The first expansion valve is for making the refrigerant flowing into the liquid pipe in the cooling operation into a two-phase state,
R32 is used as the refrigerant,
When the inner diameter of the liquid pipe is D [m] and the length of the liquid pipe is L [m],
The range of the inner diameter D is 13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ ,
Inner diameter D and length L are
L ≦ 1.15 × 10 ³ × D + 1.2
Air conditioner that satisfies the relationship. When the cooling degree of the refrigerant flowing out of the first heat exchanger in the cooling operation is SC [K],
The inner diameter D, length L and supercooling degree SC are
SC ≦ −0.003 × L / D + 4.0
The air conditioning apparatus according to claim 1, wherein the relationship is satisfied. A compressor, a first heat exchanger, a first expansion valve, a second expansion valve, and a second heat exchanger are connected via a refrigerant pipe, and include a refrigerant circuit that circulates a refrigerant therein,
The first expansion valve and the second expansion valve are connected via a liquid pipe that is a part of the refrigerant pipe,
The refrigerant circuit is capable of cooling operation in which the first heat exchanger functions as a condenser and the second heat exchanger functions as an evaporator,
The first expansion valve is for making the refrigerant flowing into the liquid pipe in the cooling operation into a two-phase state,
R32 is used as the refrigerant,
The inner diameter of the liquid pipe is D [m], the length of the liquid pipe is L [m], and the supercooling degree of the refrigerant flowing out of the first heat exchanger in the cooling operation is SC [K]. When
The range of the inner diameter D is 13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ ,
The inner diameter D, length L and supercooling degree SC are
SC ≦ −0.003 × L / D + 4.0
Air conditioner that satisfies the relationship. A compressor, a first heat exchanger, a first expansion valve, a second expansion valve, and a second heat exchanger are connected via a refrigerant pipe, and include a refrigerant circuit that circulates a refrigerant therein,
The first expansion valve and the second expansion valve are connected via a liquid pipe that is a part of the refrigerant pipe,
The refrigerant circuit is capable of cooling operation in which the first heat exchanger functions as a condenser and the second heat exchanger functions as an evaporator,
The first expansion valve is for making the refrigerant flowing into the liquid pipe in the cooling operation into a two-phase state,
R410A is used as the refrigerant,
When the inner diameter of the liquid pipe is D [m] and the length of the liquid pipe is L [m],
The range of the inner diameter D is 13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ ,
Inner diameter D and length L are
L ≦ 1.00 × 10 ³ × D-3.3
Air conditioner that satisfies the relationship. When the cooling degree of the refrigerant flowing out of the first heat exchanger in the cooling operation is SC [K],
The inner diameter D, length L and supercooling degree SC are
SC ≦ −0.005 × L / D + 3.7
The air conditioning apparatus according to claim 4 satisfying the relationship: A compressor, a first heat exchanger, a first expansion valve, a second expansion valve, and a second heat exchanger are connected via a refrigerant pipe, and include a refrigerant circuit that circulates a refrigerant therein,
The first expansion valve and the second expansion valve are connected via a liquid pipe that is a part of the refrigerant pipe,
The refrigerant circuit is capable of cooling operation in which the first heat exchanger functions as a condenser and the second heat exchanger functions as an evaporator,
The first expansion valve is for making the refrigerant flowing into the liquid pipe in the cooling operation into a two-phase state,
R410A is used as the refrigerant,
The inner diameter of the liquid pipe is D [m], the length of the liquid pipe is L [m], and the supercooling degree of the refrigerant flowing out of the first heat exchanger in the cooling operation is SC [K]. When
The range of the inner diameter D is 13.88 × 10 ⁻³ ≦ D ≦ 17.05 × 10 ⁻³ ,
The inner diameter D, length L and supercooling degree SC are
SC ≦ −0.005 × L / D + 3.7
Air conditioner that satisfies the relationship.

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