The advantages and disadvantages of accessories configuration on refrigeration system in environmental test equipment

1. Overview

Some companies refrigeration system configuration, some accessories on the book must be fully matched. Is it really necessary to match all the accessories? Is it always good to have it all together? Anyway, nothing, just analyze it, share it with all friends, as to whether it is correct, it is a matter of opinion.

2. Oil separator

The oil separator can backflow most of the compressor lubricating oil brought out from the compressor exhaust port, and a small part of the oil can be returned by the compressor suction port with the refrigerant through the circulation of the system. If the system oil return is not smooth, the oil will gradually collect in the system, which will still cause the heat transfer efficiency to decline, the compressor oil shortage and other faults. On the contrary, for refrigerants that are slightly soluble with oil, such as R404a, the over-oil separator will increase the saturation of the refrigerant dissolved oil. For large systems, because the system pipeline is thicker, the oil return is generally smooth, and the amount of oil is more, the oil distribution separator is more suitable, and for small systems, the smooth flow of the system's oil return is the key to the oil circuit, and the role of the oil separator is not large.

3. Liquid accumulator

The liquid accumulator makes the uncondensed refrigerant in the refrigeration system not enter or enter the circulation system less, improving the heat transfer efficiency, but at the same time, it will bring about the problem of increasing the refrigerant charge and low condensing pressure. For small systems, the circulation flow is not large, and the purpose of liquid accumulation can be achieved through pipeline processing technology.

4, evaporation pressure regulating valve

The evaporation pressure regulator is generally used in the dehumidification system to control the evaporation temperature so that the evaporator does not frost. However, in the unipolar circulation system, the use of evaporation pressure regulating valve must be connected to the refrigeration return air solenoid valve, which makes the pipeline structure complicated and is not conducive to the smooth system. At present, most test chambers are not equipped with evaporative pressure regulating valves.

5. Heat exchanger

The heat exchanger has three advantages, one is that the condensed refrigerant can be supercooled, reducing the amount of advance gasification in the pipeline, the second is that the return refrigerant can be fully vaporized, reducing the risk of liquid shock, and the third is that the system efficiency can be improved. However, the access of the heat exchanger complicates the piping of the system, and the pipe loss will be increased if the pipeline layout is not focused on the process. Not conducive to small batch production company product configuration.

6. Check valve

Since the system is used in multiple circulation branches, a check valve is installed at the air return port of the inactive circulation branch to prevent the accumulation of refrigerant back into the inactive circulation space. If the accumulation of gas in the pipeline does not affect the work of the system, it is necessary to consider preventing the accumulation of liquid. Therefore, not all sub-circuits need to be equipped with check valves.

7. Gas-liquid separator

The gas-liquid separator is one of the effective means to avoid liquid shock and adjust the cooling capacity appropriately for the refrigeration system with variable operating conditions. However, the gas-liquid separator also cuts off the system's oil return, so the installation of the gas-liquid separator must install the oil separator. For the unit composed of Taikang fully enclosed compressor, because there is an appropriate buffer space in the air return port, it can play a certain role in gasification, so the gas-liquid separator can be omitted. For units with limited installation space, thermal bypass can be set up to vaporize excess return liquid.

8, cold PID control

Cooling capacity PID control has a remarkable effect on energy saving in operation. Not only that, in the normal temperature (about 20℃) section where the temperature field index of thermal balance mode is relatively poor, the cooling capacity PID control system can achieve an ideal index. In terms of constant temperature and humidity can also reflect a good effect, so the cooling capacity PID control has been a more advanced technology for the test product refrigeration system. Cold PID control is divided into two kinds of time proportion and opening proportion, the time proportion is to control the refrigeration solenoid valve in a time period, the opening proportion is to control the flux of the electronic expansion valve.

However, in the time proportional control, the life of the solenoid valve is a bottleneck, the best solenoid valve on the market is estimated, and the life is only 3 to 5 years, so it is necessary to calculate whether the maintenance cost is lower than the energy saving. The electronic expansion valve in the proportional control of opening is currently expensive, and it is inconvenient to purchase on the market, because it is also dynamic balance, and it also involves life problems