WO2012056887A1

WO2012056887A1 - Refrigeration cycle apparatus

Info

Publication number: WO2012056887A1
Application number: PCT/JP2011/073477
Authority: WO
Inventors: 佐藤博
Original assignee: サンデン株式会社
Priority date: 2010-10-28
Filing date: 2011-10-13
Publication date: 2012-05-03
Also published as: JP5713312B2; JP2012093048A

Abstract

Provided is a refrigeration cycle apparatus comprising a double-tube type inner heat exchanger including: an inner tube through which a refrigerant flows from an outlet of an evaporator to an inlet of a compressor for circulation in a refrigeration cycle; and an outer tube through which the refrigerant flows from an outlet of a condenser to an inlet of the evaporator. The refrigeration cycle apparatus is characterized in that a bypass hole is formed in a wall of the inner tube so that a portion of the refrigerant flowing in the outer tube flows into the inner tube. A larger amount of heat can be exchanged at the inner heat exchanger as compared with a conventional heat exchanger, while a high operation efficiency and capability are maintained.

Description

Refrigeration cycle equipment

The present invention relates to a refrigeration cycle apparatus having an internal heat exchanger used in a vapor compression refrigeration cycle of a vehicle air conditioner.

2. Description of the Related Art A heat pump cycle that performs an air conditioning operation using a refrigerant such as carbon dioxide is known that has an internal heat exchanger as described in Patent Document 1. In such a cycle device, the specific enthalpy of the evaporator inlet refrigerant is reduced and the refrigeration effect is increased by performing heat exchange between the high-temperature / high-pressure liquid-phase refrigerant and the low-temperature / low-pressure gas-phase refrigerant. This improves cycle efficiency and capacity. A schematic flow diagram of a refrigeration cycle apparatus having a conventional internal heat exchanger is shown in FIG.

Japanese Patent No. 4239256

In an internal heat exchanger used in a conventional cycle device, if the amount of heat exchange is excessively increased, the suction superheat degree of the compressor becomes abnormally high, which may adversely affect the durability of the compressor and the discharge hose. It was. In order to avoid such adverse effects, when operating the internal heat exchanger, it is necessary to set the upper limit of the heat exchange amount to such an extent that the suction superheat degree of the compressor can be suppressed within a predetermined range.

Therefore, an object of the present invention is to provide a refrigeration cycle apparatus capable of increasing the heat exchange amount of an internal heat exchanger as compared with the conventional one while maintaining high operation efficiency and operation capability.

In order to solve the above problems, a first refrigeration cycle apparatus according to the present invention includes an inner pipe in which a refrigerant circulating in the refrigeration cycle flows from the evaporator outlet to the compressor inlet in the pipe, and the refrigerant condenses in the pipe. Having a double-tube internal heat exchanger composed of an outer tube flowing from the evaporator outlet to the evaporator inlet, and a bypass hole for allowing a part of the refrigerant flowing in the outer tube to flow into the inner tube It is formed on the wall surface of the inner pipe, and the bypass hole is given an expansion action for reducing the pressure of the refrigerant flowing into the bypass hole.

In such a refrigeration cycle apparatus of the present invention, the high-temperature and high-pressure liquid-phase refrigerant after passing through the condenser is divided into a low-temperature and low-pressure two-phase refrigerant that branches a part of the liquid-phase refrigerant and passes through the bypass hole. Further, the degree of supercooling at the inlet of the expansion mechanism can be increased by exchanging heat with the low-temperature and low-pressure gas-phase refrigerant after passing through the evaporator. According to such a refrigeration cycle of the present invention, by suppressing the flow rate of the refrigerant passing through the evaporator to a low level, it is possible to suppress the pressure loss of the refrigerant in the evaporator and increase the refrigeration capacity and the cycle efficiency. . Furthermore, according to the refrigeration cycle of the present invention, the dryness of the refrigerant at the evaporator inlet can be kept low, thereby further improving the refrigeration efficiency and the cycle efficiency.

In order to properly impart an expansion action to the bypass hole, it is necessary to set the opening area of the bypass hole within an appropriate range. Although the opening area of the bypass hole is basically determined by the diameter of the bypass hole, the total opening area of the bypass hole can be easily set by forming a plurality of bypass holes having a certain hole diameter on the wall surface of the inner pipe. Is possible.

The second refrigeration cycle apparatus according to the present invention includes an inner pipe in which a refrigerant circulating in the refrigeration cycle flows from the evaporator outlet to the compressor inlet in the pipe, and the refrigerant passes through the pipe from the condenser outlet to the evaporator inlet. And a bypass wall through which a part of the refrigerant flowing in the outer pipe flows into the inner pipe is provided on the inner wall of the inner pipe. A throttle mechanism is provided on the inner peripheral surface of the outer wall of the outer pipe and upstream of the bypass hole, and a throttle mechanism for reducing the cross-sectional area of the pipe in the pipe is provided. An expansion action for reducing the pressure of the flowing refrigerant is applied. The throttle mechanism in the present invention can be configured as an orifice plate provided on the inner peripheral surface of the outer wall of the outer tube, for example. By appropriately designing the dimensions of the orifice plate, the refrigerant pressure can be reduced to a desired pressure. When such a throttle mechanism is provided, the expansion effect on the refrigerant is mainly applied to the throttle mechanism, so that the bypass hole mainly performs the flow rate adjusting function.

In such a second refrigeration cycle apparatus according to the present invention, the high-temperature and high-pressure liquid phase refrigerant after passing through the condenser is branched from the liquid phase refrigerant and allowed to pass through the bypass hole. By exchanging heat between the two-phase refrigerant and the low-temperature and low-pressure gas-phase refrigerant after passing through the evaporator, the degree of supercooling in the latter stage of the condenser can be increased. According to such a refrigeration cycle of the present invention, by suppressing the flow rate of the refrigerant passing through the evaporator to a low level, it is possible to suppress the pressure loss of the refrigerant in the evaporator and increase the refrigeration capacity and the cycle efficiency. . Furthermore, according to the refrigeration cycle of the present invention, the dryness of the refrigerant at the evaporator inlet can be kept low, thereby further improving the refrigeration efficiency and the cycle efficiency.

In the first and second refrigeration cycle apparatuses according to the present invention, it is preferable to provide a plurality of bypass holes in order to prevent the bypass holes from being blocked by foreign matter in the system. Furthermore, for convenience when drilling inward from the outside with a jig such as an end mill, the bypass hole is formed so that the hole diameter decreases from the outer peripheral surface of the inner tube toward the inner peripheral surface of the tube wall. May be.

In the first and second refrigeration cycle apparatuses according to the present invention, the ratio of the refrigerant flow rate that flows into the inner pipe from the outer pipe through the bypass hole is the refrigerant flow rate that flows in the outer pipe. Is preferably set to 5 to 35%. By bypassing the refrigerant at such a flow rate ratio, the degree of supercooling in the expansion mechanism can be increased without destabilizing the system performance of the refrigeration cycle.

In the first and second refrigeration cycle apparatuses according to the present invention, it is preferable that a differential pressure operating valve is provided on a tube wall surface of the inner tube. The valve opening pressure of the differential pressure operating valve is preferably set to 1.0 MPa or more. If the refrigerant pressure balance before and after the bypass hole becomes unstable, the refrigerant may flow backward through the bypass hole and deteriorate the performance of the refrigeration cycle. Therefore, by providing such a differential pressure operating valve, it is possible to set the pressure at the start of the bypass to a desired value, and the refrigerant flowing in the inner pipe flows back into the outer pipe through the bypass hole. Therefore, it is possible to realize a refrigeration cycle apparatus that eliminates the risk of performing stable operation and exhibits stable performance.

Further, as a modification of the refrigeration cycle apparatus according to the present invention, a mode in which the refrigerant flowing in the inner pipe and the outer pipe is replaced can be adopted. That is, in the third refrigeration cycle apparatus according to the present invention, the refrigerant circulating in the refrigeration cycle flows through the pipe from the evaporator outlet to the compressor inlet, and the refrigerant passes through the pipe from the condenser outlet to the evaporator inlet. A bypass pipe for allowing a part of the refrigerant flowing in the inner pipe to flow into the outer pipe is formed on the pipe wall surface of the inner pipe. And an expansion action is applied to the bypass hole to reduce the pressure of the refrigerant flowing into the bypass hole.

The fourth refrigeration cycle apparatus according to the present invention includes an outer pipe through which refrigerant circulating in the refrigeration cycle flows from the evaporator outlet to the compressor inlet in the pipe, and the refrigerant passes through the pipe from the condenser outlet to the evaporator inlet. A bypass wall through which a part of the refrigerant flowing in the pipe of the inner pipe flows into the pipe of the outer pipe has a double pipe type internal heat exchanger composed of an inner pipe flowing into the pipe A throttle mechanism is provided on the inner peripheral surface of the outer wall of the outer pipe and on the upstream side of the bypass hole. An expansion action for reducing the pressure of the flowing refrigerant is applied.

In the third and fourth refrigeration cycle apparatuses according to the present invention, it is possible to add an additional configuration similar to that of the first and second refrigeration cycle apparatuses described above.

According to the refrigeration cycle apparatus according to the present invention, since the pressure loss of the refrigerant in the evaporator can be suppressed by keeping the flow rate of the refrigerant passing through the evaporator low, the refrigerating capacity can be easily increased in combination with the increase in the degree of supercooling. It becomes possible to raise. That is, when improving the refrigerating capacity by increasing the degree of supercooling, the suction superheat degree of the compressor can be kept low, and the damage given to the piping members such as the compressor and the discharge hose from the compressor is minimized. It becomes possible.

It is a schematic flowchart of the refrigeration cycle apparatus concerning one embodiment of the present invention. The internal heat exchanger used in the refrigerating-cycle apparatus of FIG. 1 is shown, (A) is a perspective view, (B) is a schematic longitudinal cross-sectional view. 2 shows the internal heat exchanger of FIG. 2, (A) is a partially enlarged view in which the vicinity of the bypass hole is enlarged, and (B) is a schematic longitudinal sectional view for explaining a position where the bypass hole is formed. It is a schematic longitudinal cross-sectional view which shows the modification of the internal heat exchanger of FIG. It is a schematic flowchart of the refrigeration cycle apparatus which concerns on the other embodiment of this invention. It is a schematic longitudinal cross-sectional view which shows the internal heat exchanger used in the refrigeration cycle apparatus of FIG. It is a schematic flowchart of the refrigeration cycle apparatus which has the conventional internal heat exchanger.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic flow diagram of a refrigeration cycle apparatus 1 according to an embodiment of the present invention. The refrigerant circulates in the system, and the refrigerant flowing out of the condenser 2 flows into the evaporator 4 mainly through the expansion valve 8 via the outer pipe 3a of the double pipe type internal heat exchanger 3. A part of the refrigerant bypasses the evaporator 4 by flowing into the bypass hole 16 while expanding due to the expansion action of the bypass hole 16 formed on the tube wall surface of the inner tube 3b. The refrigerant evaporated in the evaporator 4 flows out of the evaporator 4, and then merges with the bypass flow flowing into the bypass hole 16 and flows into the compressor 5 via the inner pipe 3 b of the internal heat exchanger 3. . The refrigerant compressed in the compressor 5 flows into the condenser 2 and is condensed. In such a refrigeration cycle apparatus 1, the degree of superheat at the outlet of the evaporator 4 is less than the degree of superheat at the outlet of the inner pipe 3 b of the internal heat exchanger 3 (the degree of superheat at the inlet of the compressor 5). The length of the heat exchanger 3 (which affects the heat exchange amount) and the diameter of the bypass hole 16 (which affects the bypass amount) are set.

FIG. 2 shows a double-pipe internal heat exchanger 13 used in the refrigeration cycle apparatus 1 of FIG. 1, wherein (A) is a perspective view and (B) is a schematic longitudinal sectional view. The refrigerant flowing into the outer pipe 13a from the condenser 2 through the inflow pipe 6 passes through the main flow flowing into the evaporator 4 through the outflow pipe 7 and the bypass hole 26 formed on the pipe wall surface of the inner pipe 13b. Branching into a bypass flow flowing into the internal flow path of the inner pipe 13b. The refrigerant that forms this bypass flow merges with the refrigerant flowing from the evaporator 4 into the inner pipe 13 b and flows out toward the compressor 5.

2, the refrigerant flowing in the outer tube 13a exchanges heat with the refrigerant flowing in the inner tube 13b through the tube wall surface of the inner tube 13b. The bypass hole 26 is formed so that a flow resistance within a predetermined range is generated in the refrigerant flow passing therethrough, thereby having an expansion action for expanding the high-temperature / high-pressure refrigerant into a low-temperature / low-pressure refrigerant, A part of the low-pressure refrigerant is bypassed to join the low-temperature / low-pressure refrigerant after passing through the evaporator 4. In such a configuration, the refrigerant is bypassed and merged, and the latent heat of evaporation of the bypassed refrigerant is used for cooling the high-pressure refrigerant, thereby improving cycle efficiency.

FIG. 3 shows the internal heat exchanger of FIG. 2, (A) is a partially enlarged view in which the vicinity of the bypass hole 26 is enlarged, and (B) is a schematic longitudinal sectional view for explaining the position where the bypass hole 26 is formed. It is. As shown in FIG. 3A, the bypass hole 26 is formed so that the hole diameter decreases from the outer peripheral surface of the inner tube 13b toward the inner peripheral surface of the tube wall. The hole diameter of the bypass hole 26 (downstream opening diameter below the drawing) is set to a hole diameter such that the mass flow rate of the refrigerant passing through the hole is 5 to 35% of the mass flow rate of the refrigerant flowing through the internal flow path of the outer tube 13a. Has been.

Although only one bypass hole 26 in FIG. 3 is formed on the tube wall surface of the inner tube 13b, a plurality of bypass holes 26 are preferably formed from the viewpoint of preventing clogging of the holes. Further, as shown in FIG. 3B, the bypass hole 26 is preferably formed only on the upstream side of the inner tube 13b. Specifically, it is formed within a range (3D) that is three times as long as the outer diameter (D) of the outer tube 13a from the end surface 9 on the outlet side of the outer tube 13a toward the downstream side of the inner tube 13b. It is preferable. By forming the bypass hole 26 at such a position, it is possible to sufficiently secure an effective heat exchange area on the pipe wall surface of the inner pipe 13b and efficiently perform heat exchange of the refrigerant.

FIG. 4 is a schematic longitudinal sectional view showing a modified example 23 of the internal heat exchanger 13 of FIG. A pedestal 10 is formed on the tube wall surface of the inner tube 23 b, and a differential pressure operating valve 12 that prevents the refrigerant from flowing back through the bypass hole 36 is installed via the pedestal 10. The differential pressure operating valve 12 includes a valve body, a disk valve, a coil spring, and a spring seat. The valve opening pressure required to open the differential pressure actuating valve 12 is set to 1.0 MPa or more. By this, the heat load is sufficiently increased, so that the apparatus for bypassing the refrigerant flow through the bypass hole 36 is used. The performance is improved. The flow resistance of the differential pressure operating valve 12 is set to a flow resistance such that the mass flow rate of the refrigerant passing through the bypass hole 36 is 5 to 35% of the mass flow rate of the refrigerant flowing through the internal flow path of the outer tube 23a. .

FIG. 5 is a schematic flow diagram of the refrigeration cycle apparatus 11 according to another embodiment of the present invention. The refrigerant circulates in the system, and the refrigerant flowing out of the condenser 2 expands by the expansion action of the orifice 15 formed on the inner peripheral surface of the outer pipe 33a of the double pipe type internal heat exchanger 33. However, some refrigerant bypasses the evaporator 4 by flowing into a bypass hole 46 formed on the tube wall surface of the inner tube 33b. The refrigerant evaporated in the evaporator 4 flows out of the evaporator 4, and then merges with the branch flow that flows into the bypass hole 46 and flows into the compressor 5 via the inner pipe 33 b of the internal heat exchanger 33. . The refrigerant compressed in the compressor 5 flows into the condenser 2 and is condensed. In such a refrigeration cycle apparatus 1, the degree of superheat at the outlet of the evaporator 4 is less than or equal to the degree of superheat at the outlet of the inner pipe 33 b of the internal heat exchanger 33 (superheat degree at the inlet of the compressor 5). The length of the heat exchanger 33 (which affects the heat exchange amount) and the hole diameter of the bypass hole 46 (which affects the bypass amount) are set.

FIG. 6 is a schematic longitudinal sectional view showing a double-pipe internal heat exchanger 43 used in the refrigeration cycle apparatus 11 of FIG. The refrigerant that has flowed into the outer tube 43a from the condenser 2 through the inflow tube 6 passes through the orifice 25 including the orifice plate 25a formed in the middle of the inner flow path of the outer tube 43a, and then passes through the outflow tube 7 to the evaporator. 4 and the bypass flow flowing into the internal flow path of the inner pipe 43b through the bypass hole 56 formed on the pipe wall surface of the inner pipe 43b. The refrigerant forming the bypass flow joins the refrigerant flowing from the evaporator 4 into the inner pipe 43 b and flows out toward the compressor 5.

In FIG. 6, the refrigerant flowing in the outer tube 43a exchanges heat with the refrigerant flowing in the inner tube 43b via the wall surface of the inner tube 43b. The orifice 25 is formed so as to reduce the cross-sectional area of the flow path in the outer pipe 43a, and thereby has an expansion action for expanding the high-temperature / high-pressure refrigerant into the low-temperature / low-pressure refrigerant. The bypass hole 56 serves to bypass a part of the low-temperature / low-pressure refrigerant after being expanded by the orifice 25 and to join the low-temperature / low-pressure refrigerant after passing through the evaporator 4. In such a configuration, the refrigerant is bypassed and merged, and the latent heat of evaporation of the bypassed refrigerant is used for cooling the high-pressure refrigerant, thereby improving cycle efficiency.

The refrigeration cycle apparatus according to the present invention is widely used in a vapor compression refrigeration cycle of a vehicle air conditioner.

1, 11, 51 Refrigeration cycle apparatus 2

Condensers

3, 13, 23, 33, 43, 53

Internal heat exchangers

3a, 13a, 23a, 33a, 43a,

53a Outer tubes

3b, 13b, 23b, 33b, 43b, 53b Inner pipe 4 Evaporator 5 Compressor 6 Inflow pipe 7 Outflow pipe 8 Expansion valve 9 End face 10 Base 12 Differential

pressure operating valve

15, 25

Orifice

16, 26, 36, 46, 56 Bypass hole 25a Orifice plate D Outer diameter of outer pipe

Claims

A double-pipe internal heat consisting of an inner pipe in which the refrigerant circulating in the refrigeration cycle flows in the pipe from the evaporator outlet to the compressor inlet, and an outer pipe in which the refrigerant flows in the pipe from the condenser outlet to the evaporator inlet A bypass hole is formed on the wall surface of the inner pipe, and a bypass hole is formed on the wall surface of the inner pipe. The bypass hole has an exchanger and allows a part of the refrigerant flowing in the outer pipe to flow into the pipe of the inner pipe. A refrigeration cycle apparatus characterized by being provided with an expansion action for reducing the pressure of the refrigerant flowing into the tank.
A double-pipe internal heat consisting of an inner pipe in which the refrigerant circulating in the refrigeration cycle flows in the pipe from the evaporator outlet to the compressor inlet, and an outer pipe in which the refrigerant flows in the pipe from the condenser outlet to the evaporator inlet A bypass hole is provided on the inner wall surface of the inner tube, and a bypass wall is formed on the inner wall surface of the inner tube, and has a bypass hole for allowing a part of the refrigerant flowing in the outer tube to flow into the inner tube. A throttling mechanism for restricting the flow passage cross-sectional area in the pipe is provided upstream of the bypass hole, and an expansion action for reducing the pressure of the refrigerant flowing in the pipe of the outer pipe is applied to the throttling mechanism. A refrigeration cycle apparatus characterized by comprising:
The refrigeration cycle apparatus according to claim 1 or 2, wherein the bypass hole is formed such that the hole diameter decreases from the outer peripheral surface of the inner tube toward the inner peripheral surface of the tube wall.
The ratio of the refrigerant flow rate flowing into the inner pipe from the outer pipe through the bypass hole is set to 5 to 35% of the refrigerant flow flowing in the outer pipe. 4. The refrigeration cycle apparatus according to any one of 3.
The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein a plurality of the bypass holes are formed on a tube wall surface of the inner tube.
The refrigeration cycle apparatus according to any one of claims 1 to 5, wherein a differential pressure operation valve is provided on a pipe wall surface of the inner pipe.
The refrigeration cycle apparatus according to claim 6, wherein a valve opening pressure of the differential pressure operating valve is set to 1.0 MPa or more.
A double-pipe internal heat consisting of an outer pipe in which the refrigerant circulating in the refrigeration cycle flows in the pipe from the evaporator outlet to the compressor inlet, and an inner pipe in which the refrigerant flows in the pipe from the condenser outlet to the evaporator inlet A bypass hole is formed on the wall surface of the inner pipe, and a bypass hole is formed on the wall surface of the inner pipe. The bypass hole has an exchanger and allows a part of the refrigerant flowing in the inner pipe to flow into the outer pipe. A refrigeration cycle apparatus characterized by being provided with an expansion action for reducing the pressure of the refrigerant flowing into the tank.
A double-pipe internal heat consisting of an outer pipe in which the refrigerant circulating in the refrigeration cycle flows in the pipe from the evaporator outlet to the compressor inlet, and an inner pipe in which the refrigerant flows in the pipe from the condenser outlet to the evaporator inlet A bypass hole is formed on a tube wall surface of the inner tube, and a bypass wall is formed on the tube wall surface of the inner tube, and includes a bypass hole through which a part of the refrigerant flowing in the tube of the inner tube flows into the tube of the outer tube. A throttling mechanism is provided on the upstream side of the bypass hole to restrict the cross-sectional area of the flow path in the pipe, and an expansion action for reducing the pressure of the refrigerant flowing in the pipe of the inner pipe is applied to the throttling mechanism. A refrigeration cycle apparatus characterized by comprising: