Causes of frosting in the constant temperature and humidity box

 

If this kind of undesirable frosting occurs, thick ice will be formed if it is not defrosted in time, which will affect the test.

 

1. When the compressor of the constant temperature and humidity box is pressurized and leaks, the water vapor in the air is compressed into water and injected into the pipeline, causing frost.

 

2. After the process pipeline of the constant temperature and humidity box is opened, it is not sealed or repaired in time. Long-term storage and frequent start-up will cause frosting, which will bring the moisture in the air into the machine from the nozzle; there are also unsealed compressors that have been placed for a long time. If they are replaced with frost without drying, they will also form frost.

 

3. The research and development of refrigeration piping system is the key. Appropriate design and customization at the beginning will ensure the performance coordination of the constant temperature and humidity box operation. In the case of unreasonable design and customization, subsequent transformation can be improved, but the effect of the previous research and invention should not be fully achieved.

 

4. The correct operation mode and regular maintenance and management are very helpful to reduce equipment failures and abnormal situations and prolong the service life of equipment. In addition, in the development and manufacturing process of the constant temperature and humidity box, attention should be paid to the rationality of the design.

 

5. After the refrigeration evaporator is damaged, the water molecules in the freezing (storage) chamber will be brought into the compressor together with the water vapor in the air when the compressor is turned on for a long time (the generator will generate negative pressure when the generator is turned on, and the atmospheric pressure will cause moisture Water molecules in the air are brought into the machine), which can also cause frost.

 

6. If the evaporator is poorly ventilated and cannot take away the cold, the evaporator will be frosted, resulting in a low pressure table on the compressor shell, which will result in frosting on the compressor shell.

 

7. Under the normal working conditions of the constant temperature and humidity box, the compressor sucks back refrigerant vapor instead of liquid. If there is too much refrigerant in the refrigeration system, too much refrigerant oil is charged or the flow rate adjusted by the expansion valve is too large, the refrigerant is not completely evaporated in the evaporator, causing the refrigerant to be sucked back by the compressor in the form of wet vapor or liquid , It will cause frost.

 

The defrosting of the constant temperature and humidity box is mainly refrigerated by the compressor, which condenses the moisture in the air into ice crystals. The frost for defrosting is mainly on the energy storage components in the pre-cooling zone. The constant temperature and humidity box will be equipped with the corresponding defrosting program, and the general defrosting method is automatic defrosting in the low temperature room. The test box is automatically converted by the solenoid valve, and the high-temperature and high-pressure gas at the discharge end of the compressor is introduced into the refrigeration evaporator to increase the surface temperature of the evaporator by absorbing heat, and the frost becomes water and then discharged to achieve the purpose of defrosting.