JP2009300002A - Refrigerating cycle device - Google Patents

Abstract

A refrigeration cycle apparatus including a refrigerant distributor that can evenly distribute refrigerant to each branch pipe even when a refrigerant having a boiling point of −40 ° C. or higher is used.
A refrigerant circuit in which a compressor, a condenser, a pressure reducing valve, and an evaporator are connected by a refrigerant pipe, and a refrigerant pipe between the pressure reducing valve and the evaporator or the inside of the evaporator is provided. The refrigerant distributor 10 includes an inflow pipe 11 on the upstream side in the refrigerant flow direction, and a plurality of branch pipes 12 connected to the inflow pipe 11 and on the downstream side in the refrigerant flow direction. In the refrigerant circuit, the refrigerant distributor 10 is installed so that the refrigerant having a boiling point of −40 ° C. or higher circulates and the flow of the refrigerant flowing through the inflow pipe 11 of the refrigerant distributor 10 becomes an upward flow. It is.
[Selection] Figure 1

Description

  The present invention relates to a refrigeration cycle apparatus used for applications such as air conditioning and freezing / refrigeration.

  In order to improve the heat exchange efficiency in the evaporator, there has been proposed a refrigeration cycle apparatus provided with a refrigerant distributor composed of an inflow pipe and a plurality of branch pipes between the pressure reducing valve and the evaporator. This refrigerant distributor fulfills the function of distributing the gas-liquid two-phase refrigerant flowing from the evaporator into the inlet pipe of the refrigerant distributor to each heat transfer pipe of the evaporator via the branch pipe. As a conventional refrigeration cycle apparatus provided with such a refrigerant distributor, for example, “a distribution chamber 14 is provided in the main flow path 12 via a distribution hole 13 having a diameter smaller than the diameter of the main flow path 12 connected to the heat exchanger. Then, a plurality of distribution chambers 14 are arranged and a plurality of heat transfer tubes 2 constituting a heat exchanger are connected to each of them ”(see, for example, Patent Document 1).

JP-A-10-267468 (summary, FIG. 1)

  A conventional refrigeration cycle apparatus including a refrigerant distributor is configured on the assumption that an HFC refrigerant such as R410A or R407C circulates. However, these refrigerants have a high global warming potential, and when the refrigerant leaks, there is a problem of promoting the global greenhouse effect. For example, the global warming potential of R410A is about 2000 times that of carbon dioxide, and the global warming potential of R407C is about 1800 times that of carbon dioxide. For this reason, it has been desired to use a refrigerant having a small global warming potential in the refrigeration cycle apparatus. Among refrigerants having a small global warming potential, those expected to be put to practical use include, for example, tetrafluoropropene and R152a. Tetrafluoropropene has a global warming potential of about 1/500 of that of R410A, and R152a has a global warming potential of about 1/200 of that of R410A.

  However, these refrigerants having a low global warming potential have a higher boiling point than conventional refrigerants. Since a refrigerant having a high boiling point has a large pressure loss when flowing through the refrigerant distributor, it is necessary to reduce the pressure loss by increasing the pipe diameter of the refrigerant distributor. For this reason, the liquid refrigerant flowing through the inlet pipe of the refrigerant distributor is unevenly distributed, and the distribution of the refrigerant flowing into each branch pipe (ratio between the liquid refrigerant and the gaseous refrigerant) becomes uneven. In addition, a refrigerant having a high boiling point, particularly a refrigerant having a boiling point of −40 ° C. or higher, has an extremely reduced droplet flow rate ratio (ratio of droplet flow rate to total refrigerant liquid flow rate). For this reason, the distribution of the refrigerant flowing into each branch pipe becomes even more uneven. Therefore, when a refrigerant having a high boiling point, particularly a refrigerant having a boiling point of −40 ° C. or higher is used in the refrigeration cycle apparatus, there is a problem that the refrigerant cannot be evenly distributed by the refrigerant distributor.

  The present invention has been made to solve the above-described problems, and is a refrigeration equipped with a refrigerant distributor that can evenly distribute the refrigerant to each branch pipe even when a refrigerant having a boiling point of −40 ° C. or higher is used. The object is to obtain a cycle device.

  The global warming potential is the ratio of the effect of each greenhouse gas that causes global warming to the effect of carbon dioxide, which is approved by the Intergovernmental Panel on Climate Change (IPCC) This is the value agreed by the Conference of the Parties.

  The refrigeration cycle apparatus according to the present invention includes a refrigerant circuit in which a compressor, a condenser, a pressure reducing valve, and an evaporator are connected by a refrigerant pipe, and a refrigerant pipe or the evaporator between the pressure reducing valve and the evaporator of the refrigerant circuit. A refrigerant distributor provided inside the refrigerant distributor, the refrigerant distributor including an inflow pipe on the upstream side in the refrigerant flow direction, and a plurality of branch pipes connected to the inflow pipe and on the downstream side in the refrigerant flow direction. The refrigerant distributor is installed in the refrigerant circuit so that a refrigerant having a boiling point of −40 ° C. or more circulates and the flow of the refrigerant flowing through the inlet pipe of the refrigerant distributor is an upward flow. It is what has been.

  According to the present invention, since the flow of the refrigerant flowing through the inflow pipe is an upward flow, the liquid refrigerant is less likely to be unevenly distributed in the cross section of the inflow pipe. For this reason, even if a refrigerant having a boiling point of −40 ° C. or higher is used, the refrigerant flowing through the inflow pipe can be evenly distributed to the branch pipes. Therefore, the efficiency of the refrigeration cycle apparatus is improved.

Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 1 of the present invention. In addition, the arrow shown in FIG. 1 represents the flow direction of a refrigerant | coolant. The refrigerant circuit of the refrigeration cycle apparatus 1 is configured by sequentially connecting a compressor 2, a condenser 3, a pressure reducing valve 4, and an evaporator 5 with refrigerant piping. In the refrigeration cycle apparatus 1 according to Embodiment 1, a refrigerant distributor 10 is provided between the pressure reducing valve 4 and the evaporator 5. The refrigeration cycle apparatus 1 uses a refrigerant mainly composed of tetrafluoropropene or difluoroethane, for example, a refrigerant mainly composed of 2,3,3,3-tetrafluoropropene or 1,1-difluoroethane (R152a). . The “tetrafluoropropylene” and “difluoroethane” refer to all tetrafluoropropylene and difluoroethane including various isomers.

  FIG. 2 is a schematic longitudinal sectional view of the refrigerant distributor according to Embodiment 1 of the present invention. In addition, the arrow shown in FIG. 2 represents the flow direction of a refrigerant | coolant. The refrigerant distributor 10 includes an inflow pipe 11 and a plurality of branch pipes 12. The inflow pipe 11 is a substantially cylindrical pipe. In a state where the refrigeration cycle apparatus 1 is installed, the inflow pipe 11 is installed in a substantially vertical direction. At this time, the lower end of the inflow pipe 11 serves as a refrigerant inflow port, and the upper end of the inflow pipe 11 serves as a refrigerant outflow port. That is, the inflow pipe 11 is installed so that the flow of the refrigerant flowing through the inflow pipe 11 becomes an upward flow. The branch pipe 12 is a substantially cylindrical pipe. One end of each of the plurality of branch pipes 12 (refrigerant inlet) is connected to the outlet (tip) of the inlet pipe 11 via the joint 13 by, for example, brazing. The other end of the branch pipe 12 (refrigerant outlet) is connected to the heat transfer pipe of the evaporator 5.

  In the first embodiment, the installation direction of the inflow pipe 11 is set to a substantially vertical direction (the direction in which the flow of the refrigerant flowing through the inflow pipe 11 becomes an upward flow), but this is relative to the vertical direction of the central axis of the inflow pipe 11. This represents a state where the inclination is 4 ° or less. By installing the inflow pipe 11 in this way, the vertical direction component of gravity acting on the refrigerant flowing through the inflow pipe 11 is between the gaseous refrigerant and the liquid film formed by the liquid refrigerant on the inner wall of the inflow pipe 11. The frictional force acting between them is reduced to about 1/10. For this reason, the refrigerant in the inflow pipe 11 is not unevenly distributed in the cross section of the inflow pipe 11.

  In the first embodiment, the pipe diameter of the inflow pipe 11 is larger than the pipe diameter of the refrigerant pipe connected to the inlet of the inflow pipe 11 (FIG. 1). The pipe diameters of the refrigerant pipes connected to the inlet of the inflow pipe 11 may be the same. A refrigerant pipe between the pressure reducing valve 4 and the evaporator 5 may be used as the inflow pipe 11 and the branch pipe 12 may be connected to the refrigerant pipe. In this case, a portion of the refrigerant pipe that is installed in a substantially vertical direction corresponds to the inflow pipe 11.

(Description of operation)
Next, the operation of the refrigeration cycle apparatus of the present invention will be described.
FIG. 3 is a ph diagram showing the transition of the refrigerant in the refrigeration cycle apparatus according to Embodiment 1 of the present invention. In addition, the refrigerant | coolant state of ad shown in FIG. 3 is a refrigerant | coolant state in the location shown by ad in FIG. 1, respectively. Moreover, the arrow shown in FIG. 3 represents the flow direction of a refrigerant | coolant.
A low-temperature and low-pressure gaseous refrigerant is compressed by the compressor 2 and discharged as a high-temperature and high-pressure refrigerant. The refrigerant compression process of the compressor 2 is represented by an isentropic curve shown from points a to b in FIG. 3 assuming that heat does not enter and leave the surroundings. The high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the condenser 3. And it is condensed and liquefied while dissipating heat to air or water in the condenser 3 to become a high-pressure liquid refrigerant. The change of the refrigerant in the condenser 3 is performed under a substantially constant pressure. The refrigerant change at this time is represented by a slightly inclined straight line that is slightly inclined from the point b to c in FIG. 3 in consideration of the pressure loss of the condenser 3.

  The high-pressure liquid refrigerant that has come out of the condenser 3 flows into the pressure reducing valve 4. Then, the high-pressure liquid refrigerant is throttled by the pressure-reducing valve 4 to expand (decompress) and enter a low-temperature low-pressure gas-liquid two-phase state. The refrigerant dryness at this time is about 0.1 to 0.3. The change of the refrigerant in the pressure reducing valve 4 is performed under a constant enthalpy. The refrigerant change at this time is represented by the vertical line shown from the point c to d in FIG.

  The low-temperature and low-pressure refrigerant in the gas-liquid two-phase state that exits the pressure reducing valve 4 flows into the inflow pipe 11 of the refrigerant distributor 10. The refrigerant flowing into the inflow pipe 11 is distributed to each branch pipe 12 and flows into the heat transfer pipe of the evaporator 5. And it becomes a low-temperature and low-pressure gaseous refrigerant, while dissipating heat to air and water by the evaporator 5. The change of the refrigerant in the evaporator 5 is performed under a substantially constant pressure. The refrigerant change at this time is represented by a slightly inclined horizontal line shown from point d to a in FIG. 3 in consideration of the pressure loss of the evaporator 5. The low-temperature and low-pressure gaseous refrigerant exiting the evaporator 5 flows into the compressor 2 and is compressed.

(Refrigerant characteristics)
As described above, the refrigeration cycle apparatus 1 uses a refrigerant mainly composed of tetrafluoropropene or R152a. These refrigerants differ in distribution performance between the conventional refrigerant (for example, R410A) and the refrigerant distributor 10 due to physical properties. Therefore, the difference in distribution performance between the tetrafluoropropene and the refrigerant distributor 10 of R152a and R410A will be described below.

FIG. 4 is a characteristic diagram showing the characteristics of tetrafluoropropene and R152a and R410A. FIG. 4 shows the liquid density and vapor density, density ratio (vapor density / liquid density), surface tension, and boiling point of each refrigerant at a refrigerant temperature of 25 ° C.
As shown in FIG. 4, the boiling points of tetrafluoropropene and R152a are −29 ° C. and −24 ° C., respectively, which is higher than the boiling point of R410A (−51 ° C.). When the boiling point of the refrigerant is high, the vapor density decreases, and the pressure loss generated when flowing in the pipe increases. Moreover, the capacity | capacitance and performance of a refrigerating-cycle apparatus fall, so that the pressure loss of a refrigerant | coolant is large. For this reason, in order to use tetrafluoropropene and R152a in the refrigeration cycle apparatus with the same pressure loss as R410A, it is necessary to increase the pipe diameter of the refrigeration cycle apparatus to about 1.3 times and 1.15 times, respectively. There is. When the pipe diameter of the refrigeration cycle apparatus is increased, the flow rate of the refrigerant flowing through the pipe decreases.

  Therefore, when tetrafluoropropene or R152a is used as the refrigerant of the refrigeration cycle apparatus, in the inflow pipe 11 through which the gas-liquid two-phase refrigerant flows, the shear stress acting on the interface between the liquid refrigerant and the gaseous refrigerant is reduced, and R410A Compared to the above, the liquid refrigerant and the gaseous refrigerant are separated and easily flow. For this reason, the liquid film formed on the inner wall of the inflow pipe 11 is likely to be unevenly distributed depending on the installation posture and shape of the inflow pipe 11, and the distribution of the refrigerant flowing into each branch pipe 12 is likely to be uneven. That is, it is difficult to supply each branch pipe 12 with the liquid refrigerant in an amount corresponding to the flow rate of the gaseous refrigerant flowing into each branch pipe 12.

  Further, as shown in FIG. 4, the surface tension of tetrafluoropropene having a high boiling point and R152a are 0.008 N / m and 0.010 N / m, respectively, and the surface tension of R410A having a low boiling point (0.005 N / m). greater than m). Normally, when a gas-liquid two-phase refrigerant flows in a pipe, the more liquid refrigerant that flows as droplets, the more equally the refrigerant can be distributed. This is because the liquid refrigerant that has become droplets can move along the flow of the gaseous refrigerant. However, tetrafluoropropene and R152a, which have a higher surface tension than R410A, have a larger droplet diameter than R410A. For this reason, tetrafluoropropene and R152a are less likely to form droplets than R410A.

  FIG. 5 is a characteristic diagram showing the relationship between the boiling point of the refrigerant and the droplet flow rate ratio. FIG. 5 shows a case where the refrigerant flows through the pipe where the pressure loss per unit pipe length is about the same in a state where the refrigerant flow rate is 60 kg / h, the dryness is 0.2 to 0.5, and the refrigerant temperature is 10 ° C. The relationship between the boiling point of the refrigerant and the droplet flow rate ratio is shown. The droplet flow rate ratio represents the ratio of the droplet flow rate to the total refrigerant liquid flow rate.

  As can be seen from FIG. 5, the refrigerant having a boiling point of −40 ° C. or higher has an extremely small droplet flow rate ratio. That is, tetrafluoropropene and R152a, which are refrigerants having a boiling point of −40 ° C. or higher, have an extremely small droplet flow rate ratio. Therefore, when tetrafluoropropene or R152a is used as the refrigerant of the refrigeration cycle apparatus, in the inflow pipe 11 through which the gas-liquid two-phase refrigerant flows, the distribution of the refrigerant flowing into the branch pipes 12 tends to be uneven. When tetrafluoropropene or R152a is used as the refrigerant for the refrigeration cycle apparatus, the pipe diameter of the refrigeration cycle apparatus must be increased as described above, so that the liquid refrigerant flowing in the pipe is less likely to become liquid droplets. The distribution of the refrigerant flowing into the pipe 12 tends to be more uneven.

  As described above, a refrigerant mainly composed of tetrafluoropropene or R152a, which is likely to cause uneven distribution of refrigerant in the refrigerant distributor 10, is used in the refrigeration cycle apparatus 1, and the refrigerant distributor 10 according to the first embodiment is used. Then, as shown below, it is possible to evenly distribute the refrigerant. Hereinafter, the flow pattern of the refrigerant flowing in the inflow pipe 11 of the refrigerant distributor 10 will be described.

  FIG. 6 is an enlarged view of a main part showing the flow mode of the refrigerant flowing through the inflow pipe 11 according to Embodiment 1 of the present invention. For ease of explanation, FIG. 6 shows the inflow pipe 11 with a part thereof broken. In addition, the arrow shown in FIG. 6 represents the flow direction of a refrigerant | coolant.

  The flow mode of the refrigerant flowing through the inflow pipe 11 is a flow mode generally called an annular spray flow. That is, a part of the liquid refrigerant flows by forming the liquid film 101 so as to cover the inner wall of the inflow pipe 11. The remaining part of the liquid refrigerant is dispersed as droplets 102 and flows in the vicinity of the central portion of the inflow pipe 11 together with the gaseous refrigerant. At this time, since the flow direction of the refrigerant flowing through the inflow pipe 11 is an upward flow (because it is flowing substantially vertically upward), the uneven distribution of the liquid film (transverse of the inflow pipe 11) which is a problem in tetrafluoropropene or R152a. Uneven distribution on the surface), and the thickness of the liquid film is almost uniform. Similarly, the wave 101a generated unsteadyly on the upper surface of the liquid film 101 is also less likely to be unevenly distributed in the cross section of the inflow pipe 11. Therefore, even if the pipe connected to the upstream side of the refrigerant distributor 10 has a horizontally installed portion or a bent portion, and the refrigerant flows in a so-called laminar flow or wave flow, the refrigerant flows in the inflow pipe 11. Since the mode is an annular spray flow, the refrigerant composed of the liquid film 101, the droplets 102, and the refrigerant vapor flows into the branch pipe 12 evenly.

  In the first embodiment, the flow mode of the refrigerant flowing through the inflow pipe 11 is an annular spray flow. However, other flow modes such as an annular flow may be used. If the flow direction of the refrigerant flowing through the inflow pipe 11 is an upward flow, the liquid refrigerant in the cross section of the inflow pipe 11 is not unevenly distributed, and the refrigerant flowing through the inflow pipe 11 is evenly distributed to the branch pipes 12.

  In the refrigeration cycle apparatus 1 configured in this way, the flow of the refrigerant flowing through the inflow pipe 11 is an upward flow, so that the liquid refrigerant is not unevenly distributed in the cross section of the inflow pipe 11. For this reason, even if a refrigerant having a boiling point of −40 ° C. or higher is used, the refrigerant flowing through the inflow pipe 11 can be evenly distributed to the branch pipes 12. Therefore, the efficiency of the refrigeration cycle apparatus is improved.

  Further, since the flow mode of the refrigerant flowing through the inflow pipe 11 is an annular spray flow or an annular flow, uneven distribution in the cross section of the liquid film 101 formed on the inner wall of the inflow pipe 11 does not occur. For this reason, the thickness of the liquid film 101 of the liquid refrigerant formed on the inner wall of the inflow pipe 11 becomes uniform. Therefore, the refrigerant flowing through the inflow pipe 11 can be more evenly distributed to the branch pipes 12.

  Moreover, since the refrigerant | coolant whose global warming potential is 150 or less, such as a refrigerant | coolant which has tetrafluoropropene or R152a as a main component, is used for the refrigerating-cycle apparatus 1, even when a refrigerant | coolant leaks, the greenhouse effect is suppressed. be able to.

  In the first embodiment, the length of the inflow pipe 11 (the length from the inlet of the inflow pipe 11 to the inlet of the branch pipe 12) is not particularly described. For example, the length of the inflow pipe 11 is It is preferable that the length of the inflow pipe 11 is not less than 5 times, preferably not less than 10 times the inner diameter. By doing so, the flow mode of the refrigerant flowing through the inflow pipe 11 becomes an annular spray flow or an annular flow.

  Although the inner wall shape of the inflow pipe 11 is not particularly described in the first embodiment, a groove may be formed in the inner wall of the inflow pipe 11. According to such a form, the large surface tension of tetrafluoropropene or R152a acts effectively, and a stable liquid film 101 can be formed on the inner wall of the inflow pipe 11. For this reason, the length of the inflow pipe 11 installed so that it may become an upward flow can be shortened, and the effect that a refrigerant distributor can be reduced in size is acquired. The groove formed on the inner wall of the inflow pipe 11 may be a straight groove substantially parallel to the central axis (refrigerant flow direction) of the inflow pipe 11, or the central axis (refrigerant flow direction) of the inflow pipe 11. A spiral groove having a predetermined angle may be used. That is, the groove formed on the inner wall of the inflow pipe 11 may be a groove that allows the refrigerant to flow along the groove (so that the refrigerant does not get over the groove).

  Further, in the present embodiment, the refrigerant distributor 10 is provided between the pressure reducing valve 4 and the evaporator 5, but the same effect can be obtained by providing the refrigerant distributor 10 in a path through which the refrigerant flows in a gas-liquid two-phase state. Is obtained. For example, in order to reduce pressure loss, the heat transfer tube may be branched in the evaporator, but the refrigerant distributor 10 may be provided at this branch.

Further, in the first embodiment, the relationship between the in-pipe diameter D1 of the inflow pipe 11 and the in-pipe diameter D2 of the branch pipe 12 is not particularly described. However, the pressure loss per unit length of the branch pipe 12 is caused by the inflow pipe. It is preferable that the pressure loss be greater than 11 unit lengths. For example, when the number of branch pipes 12 is n, it is preferable to determine the pipe inner diameter D1 of the inflow pipe 11 and the pipe inner diameter D2 of the branch pipe 12 so as to satisfy the following expression (1). According to such a form, the pressure loss of the refrigerant distributor 10 can be minimized, and the efficiency of the refrigeration cycle apparatus 1 is improved.
1 ≦ D1 / D2 ≦ n ^0.368 (1)

  In the first embodiment, the refrigerant distributor 10 in which the branch pipe 12 is connected to the tip of the inflow pipe 11 has been described. However, for example, the side surface of the inflow pipe 11 is arranged so that the refrigerant flowing through the inflow pipe 11 is sequentially distributed. You may connect the branch pipe 12 to a part.

  In the first embodiment, the dryness in the inflow pipe 11 is not particularly described, but it is desirable that the dryness of the refrigerant flowing in is 0.15 or more. For example, FIG. 7 is a diagram illustrating the dryness of the refrigerant flowing into the inflow pipe on the horizontal axis and the mass velocity that is a value obtained by dividing the mass flow rate by the cross-sectional area of the inflow pipe on the vertical axis. The circles in the figure are conditions that allow stable refrigerant distribution, and the x marks are conditions that make refrigerant distribution unstable. Therefore, according to such a form, distribution of the refrigerant distributor 10 can be performed stably, and the efficiency of the refrigeration cycle apparatus 1 is improved.

  In the first embodiment, the composition of the refrigerant mainly composed of tetrafluoropropene is not particularly described, but difluoromethane having a low boiling point may be mixed in a range of 30 weight percent or less. According to such a form, although a boiling point is -40 degreeC or more, a refrigerant | coolant can be distributed equally.

Embodiment 2. FIG.
By forming a groove in the inner wall of the inflow pipe 11, the refrigerant can be more evenly distributed to the branch pipes 12. In the second embodiment, items that are not particularly described are the same as those in the first embodiment, and the same functions and configurations are described using the same reference numerals.

  FIG. 8 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 2 of the present invention. FIG. 9 is a perspective view of the refrigerant distributor shown in FIG. In FIG. 9, the inflow pipe 11 is shown with a part thereof broken for easy explanation. Moreover, the arrow shown in FIG.8 and FIG.9 represents the flow direction of a refrigerant | coolant.

  The refrigerant distributor 10 includes an inflow pipe 11 and a plurality of branch pipes 12. The inflow pipe 11 is a substantially cylindrical pipe. In a state where the refrigeration cycle apparatus 1 is installed, the inflow pipe 11 is installed in a substantially vertical direction. At this time, the lower end portion of the inflow pipe 11 serves as a refrigerant inlet. That is, the inflow pipe 11 is installed so that the flow of the refrigerant flowing through the inflow pipe 11 becomes an upward flow. In addition, a groove 14 is formed on the inner wall of the inflow pipe 11 substantially in parallel with the central axis of the inflow pipe 11 (the flow direction of the refrigerant flowing through the inflow pipe 11).

  The branch pipe 12 is a substantially cylindrical pipe. One end of each of the branch pipes 12 (refrigerant inlet) extends from the upstream side to the downstream side in the flow direction of the refrigerant flowing through the inflow pipe 11 (that is, along the length direction of the inflow pipe 11). It is sequentially connected to the side surface of the inflow pipe 11. The other end of the branch pipe 12 (refrigerant outlet) is connected to the heat transfer pipe of the evaporator 5. In the second embodiment, the branch pipe 12 is connected to the inflow pipe 11 substantially perpendicularly, but the junction angle between the branch pipe 12 and the inflow pipe 11 can be arbitrarily set.

  In the refrigeration cycle apparatus 1 configured as described above, the liquid refrigerant in the gas-liquid two-phase refrigerant flowing through the inflow pipe 11 flows between the grooves 14 by capillary force, and forms a liquid film 101 on the inner wall of the inflow pipe 11. To do. Further, the liquid refrigerant flowing between the grooves 14 does not get over the grooves 14 due to shear stress generated at the interface between the liquid refrigerant flowing between the grooves 14 and the gaseous refrigerant flowing through the substantially central portion of the inflow pipe 11. That is, the liquid film 101 is not disturbed. For this reason, the temporally or spatially non-uniform flow peculiar to gas-liquid two-phase flow (for example, wave 101a etc. which generate | occur | produces on the liquid film 101) can be suppressed, and the stable liquid film 101 is made into the inner wall of the inflow tube 11. Can be formed. Thereby, the liquid refrigerant of the quantity according to the flow volume of the gaseous refrigerant which flows into each branch pipe 12 can be supplied to each branch pipe 12, and an evaporator can be operated efficiently.

Embodiment 3 FIG.
Depending on the installation conditions of the refrigerant distributor 10, such as the installation location of the refrigeration cycle apparatus 1 and the structure of the evaporator, the inflow pipe 11 may not be installed in a substantially vertical direction. Even in such a case, the present invention can be implemented in the same manner as in the third embodiment. In Embodiment 3, items that are not particularly described are the same as those in Embodiment 1 or Embodiment 2, and the same functions and configurations are described using the same reference numerals.

FIG. 10 is a perspective view of a refrigerant distributor according to Embodiment 3 of the present invention. In addition, in order to make description easy in FIG. Moreover, the arrow shown in FIG. 10 represents the flow direction of a refrigerant | coolant.
On the inner wall of the inflow pipe 11, a spiral groove 14 having an inclination α with respect to the central axis of the inflow pipe 11 (the flow direction of the refrigerant flowing through the inflow pipe 11) is formed. By configuring the refrigerant distributor 10 in this way, the liquid refrigerant that tends to be unevenly distributed on the inner wall 11a side flows to the inner wall 11b side through the groove 14 by capillary force. Therefore, even when the inflow pipe 11 is installed in such a posture that the flow direction of the refrigerant does not become a substantially vertical direction, a stable liquid film 101 can be formed on the inner wall of the inflow pipe 11, and the refrigerant flowing through the inflow pipe 11 can be evenly distributed. It can be distributed to the branch pipe 12.

Although the number and dimensions of the grooves 14 are not described in the third embodiment, the number Na of the grooves 14 is set to the number Nc of grooves that are cut at the junction between the inflow pipe 11 and the branch pipe 12 in the groove 14. It may be larger than twice. In addition, the groove | channel cut | disconnected by the junction part of the inflow pipe 11 and the branch pipe 12 is a groove | channel which crosses the branch pipe 12 in FIG. In FIG. 11, Nc = 8. In the refrigerant distributor 10 having such a configuration, in addition to the effects of the third embodiment, the refrigerant distributor 10 is connected to the most upstream side of the refrigerant flow in which the ratio between the flow rate of the gaseous refrigerant and the flow rate of the liquid refrigerant is likely to be biased. A large amount of liquid refrigerant does not flow into the branch pipe 12 as well. For this reason, a liquid refrigerant can be supplied also to the branch pipe 12 connected to the refrigerant flow downstream side.
When the number of branch pipes 12 (the number of branches) is Ns, the number Na of grooves 14 is determined so as to satisfy the relationship Na ≧ Nc × Ns, whereby the branch pipe 12 on the upstream side of the refrigerant flow is supplied. The drift of the liquid refrigerant can be further suppressed, and the effect that the liquid refrigerant can be evenly distributed to the branch pipes 12 can be obtained.

3 is a refrigerant circuit diagram of the refrigeration cycle apparatus according to Embodiment 1. FIG. 3 is a schematic longitudinal sectional view of a refrigerant distributor according to Embodiment 1. FIG. FIG. 3 is a ph diagram showing the change of refrigerant in the refrigeration cycle apparatus according to Embodiment 1. It is a characteristic view which shows the characteristic of tetrafluoro propene and R152a and R410A. It is a characteristic view which shows the relationship between the boiling point of a refrigerant | coolant, and a droplet flow rate ratio. FIG. 3 is an enlarged view of a main part showing a flow mode of a refrigerant flowing through an inflow pipe 11 according to Embodiment 1. It is a characteristic view which shows the relationship between the dryness of a refrigerant | coolant, and mass velocity. 6 is a refrigerant circuit diagram of a refrigeration cycle apparatus according to Embodiment 2. FIG. 6 is a perspective view of a refrigerant distributor according to Embodiment 2. FIG. 6 is a perspective view of a refrigerant distributor according to Embodiment 3. FIG. 6 is a partial development view of an inflow pipe 11 according to Embodiment 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle apparatus, 2 Compressor, 3 Condenser, 4 Pressure reducing valve, 5 Evaporator, 10 Refrigerant distributor, 11 Inflow pipe, 11a Inner wall, 11b Inner wall, 12 Branch pipe, 13 Joint part, 14 Groove, 101 Liquid film , 101a waves, 102 droplets.

Claims (10)

A refrigerant circuit in which a compressor, a condenser, a pressure reducing valve and an evaporator are connected by a refrigerant pipe; and a refrigerant pipe provided between the pressure reducing valve and the evaporator or a refrigerant distributor provided in the evaporator,
The refrigerant distributor has an inflow pipe on the upstream side in the refrigerant flow direction, and a plurality of branch pipes connected to the inflow pipe and on the downstream side in the refrigerant flow direction,
In the refrigerant circuit, a refrigerant having a boiling point of −40 ° C. or higher circulates,
The refrigeration cycle apparatus, wherein the refrigerant distributor is installed so that the refrigerant flowing through the inlet pipe of the refrigerant distributor is an upward flow.   The refrigeration cycle apparatus according to claim 1, wherein the refrigerant distributor is configured such that a flow mode of the refrigerant flowing through the inflow pipe is an annular spray flow or an annular flow.   The length from the inlet of the inlet pipe of the refrigerant distributor to the inlet of the branch pipe whose refrigerant flow direction is the most upstream side is at least five times the inner diameter of the inlet pipe. The refrigeration cycle apparatus according to claim 2, characterized in that:   The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein a plurality of grooves parallel to the inner wall of the inflow pipe are formed.   Each of the said branch pipes is provided in the outflow port of the front-end | tip of the said inflow pipe, The refrigeration cycle apparatus as described in any one of Claims 1-4 characterized by the above-mentioned.   Each of the said branch pipes is provided in order along the length direction of the said inflow pipe, The refrigeration cycle apparatus as described in any one of Claims 1-4 characterized by the above-mentioned. Each of the branch pipes is provided in order along the length direction of the inflow pipe,
The number Na of the grooves is
5. The refrigeration cycle apparatus according to claim 4, wherein the refrigeration cycle apparatus has more than twice the number Nc of the grooves cut by a joint portion between the inflow pipe and the branch pipe. Each of the branch pipes is provided in order along the length direction of the inflow pipe,
When the number of branches is Ns, and the number of grooves cut by the junction between the inflow pipe and the branch pipe is Nc,
The refrigeration cycle apparatus according to claim 4, wherein the number Na of the grooves is Na ≧ Nc × Ns.   The refrigeration cycle apparatus according to any one of claims 1 to 8, wherein the refrigerant is a refrigerant having a global warming potential of 150 or less.   The refrigeration cycle apparatus according to claim 9, wherein the refrigerant is a refrigerant mainly composed of tetrafluoropropene or R152a.

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