JPS6251387B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration system comprising a compressor, a condenser, a pressure reducing device, and an evaporator.

In conventional refrigeration systems of this type, a thermostatic expansion valve or a capillary tube is generally used as a pressure reducing device. The former expansion valve has the advantage of being able to reliably control superheat over a wide operating range of the evaporator. On the other hand, it is more expensive than a capillary tube, and in a multi-pass evaporator, the refrigerant is distributed unevenly by the distributor, so it is necessary to increase the superheat in order to obtain stable refrigeration operation. The disadvantage is that the thermal area cannot be used effectively.

On the other hand, capillary tubes are inexpensive and have the advantage that refrigerant can be distributed well by connecting a capillary tube to each pass in a multi-pass evaporator. On the other hand, when the operating range is wide, the superheat of the evaporator becomes excessive or liquid backlash occurs. As a means to prevent this, the heat transfer surface and capillary tube of the cooler are selected, and under normal operating conditions, the cooler is used in a significantly superheated state, which has the disadvantage that the heat transfer area of the cooler is not effectively utilized. be.

The present invention was invented in view of the above,
The purpose is to use a capillary tube to control the superheat of the evaporator even over a wide operating range, and to effectively use the heat transfer area in a multi-pass evaporator to reduce the size of the compressor. In a refrigeration system consisting of a condenser, a capillary tube, and an evaporator, a subcooler is provided between the condenser and the capillary tube, and the inlet of the subcooler and the outlet of the condenser are connected by a bypass having a thermostatic expansion valve. The outlet of the subcooler and the outlet side piping of the evaporator are connected via a bypass pipe, and the connection point between the bypass pipe and the outlet side piping of the evaporator and the compressor are connected through a pipe. The present invention is characterized in that a heat-sensitive cylinder of the expansion valve is attached to the piping.

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is a compressor, 2 is a condenser, and 3 is a compressor.
is a capillary tube, 4 is an evaporator, 5 is a subcooler provided between the condenser 2 and capillary tube 3, and 6 is a thermostatic expansion valve, which connects the outlet side of the condenser 2 and the inlet of the subcooler 5. bypass pipe 7
It is set in. 8 is a bypass pipe that communicates the outlet part of the subcooler 5 with the outlet side pipe 11 of the evaporator 4; 9 is a connection point between the pipe 11 and the bypass pipe 8;
10 is a temperature-sensitive cylinder of the temperature-type expansion valve 6, and the connection point 9
and the compressor 1.

Next, the operation of this embodiment configured as described above will be explained.

The refrigerant gas discharged from the compressor 1 is liquefied by the condenser 2, and a part of this liquid refrigerant is evaporated via the thermostatic expansion valve 6, and then introduced into the subcooler 5 via the bypass pipe 7 and cooled. , further passes through the bypass pipe 8 and joins with the refrigerant gas discharged from the evaporator 4.

On the other hand, the remainder of the liquid refrigerant is directly sent to the subcooler 5.
After being introduced into the capillary tube 3 and depressurized, the refrigerant is further introduced into the evaporator 4 and evaporated to become refrigerant gas. This refrigerant gas is sucked into the compressor 1 after joining with the refrigerant flowing through the bypass pipe 8 .

Since the refrigeration cycle of this embodiment is configured as described above, even if a capillary tube is used as the main expansion mechanism, the superheat at the inlet of the compressor 1 can be kept constant over a wide operating range.
The reason is as follows.

The flow rate characteristics of the capillary tube 3 are as shown in Figure 2, and the amount of refrigerant is
It increases with the increase in the degree of supercooling at the inlet. For example, when the heat load on the evaporator 4 increases, the superheat at the outlet of the evaporator 4 also increases, and therefore the superheat on the 10 parts of the heat-sensitive tube also increases. For this reason, the temperature-type expansion valve 6
Since the flow rate of refrigerant flowing through the capillary tube 3 increases and the degree of supercooling of the subcooler 5 also increases, the flow rate of refrigerant flowing through the capillary tube 3 increases, so that the superheat of the thermosensitive tube 10 can be set to the set value. Therefore, the superheat at the inlet of the compressor 1 can be kept constant.

As described above, according to the present invention, by adjusting the degree of supercooling of the refrigerant before the capillary tube via the subcooler, the superheat at the compressor inlet can be made constant. Therefore, it is economical because an inexpensive capillary tube can be used as the main expansion mechanism.

Further, according to the present invention, when a multi-pass evaporator is used, the refrigerant is favorably distributed by the capillary tube, so that the heat transfer area can be used effectively and the evaporator can be downsized.

[Brief explanation of the drawing]

FIG. 1 is a refrigeration cycle diagram showing an embodiment of the refrigeration system of the present invention, and FIG. 2 is a flow characteristic diagram of a capillary tube used in the present invention. 1... Compressor, 2... Condenser, 3... Capillary tube, 4... Evaporator, 5... Subcooler,
6... Temperature expansion valve, 7, 8... Bypass pipe, 9
... Connection point, 10 ... Heat-sensitive cylinder, 11 ... Piping.

Claims (1)

[Claims] 1. In a refrigeration system in which a compressor, a condenser, and a multi-pass evaporator connected to multiple parallel capillary reach tubes are sequentially connected via piping, a subcooler is provided between the condenser and the capillary reach tube, and this The inlet of the subcooler and the outlet of the condenser are communicated via a bypass pipe having a thermostatic expansion valve, and the outlet of the subcooler and the outlet of the evaporator are connected via a bypass pipe. A refrigeration system characterized in that a heat-sensitive cylinder of the expansion valve is attached to a pipe between a connection point between a bypass pipe and an outlet side pipe of an evaporator and a compressor.