Why Does Glycol Air Cooler Need Defrost?

- Dec 15, 2017-

Why does glycol air cooler, glycol evaporator need defrost? 

After glycol evaporator unit working a little while, it should be have frost on tube and fin.

It case heat transfer coefficient decreased. So the users need to use defrost system regularly.

VRcooler do have different defrosting methods for glycol air cooler.

Electric defrost

Hot gas defrost

Water defrost

Electric defrost

In small and medium freon refrigeration systems commonly used method of electric heating 

defrost. Inserted heat pipe in the air cooler or evaporator. When start defrosting system 

need to stop the operation of the air cooler, and close the valve for 

the liquid, and then turn on the power of the heating tube, then the air cooler defrosting. 

After the frost melts, turn off the power of the electric heating tube, start the 

compressor, open the liquid valve properly, and resume the operation of the glycol air cooler. 

This method consumes more energy, cold room temperature fluctuations are also large. 

However, the defrost is convenient, easy to operate and easy to realize automatic 


Hot gas defrost

Hot gas defrost (hot ammonia defrost or hot freon defrost) is that use the high temperature 

refrigerant gas discharged from the compressor, first through the oil separator then 

insert the evaporator to melt the frost layer. 

The hot working gas emits heat and then condenses into liquid, which is discharged into 

the liquid discharging bucket or the low pressure circulating liquid tank together with 

the original oil in the evaporator. This method defrosting effect is good, a short time, 

low labor intensity, however the operation is more complicated, it need to stop cooling 


Water defrost

Water defrost use of sprinkler water spray to the outer surface of the frost layer on 

evaporator, use the heat of the water to melt defrost. Advantage is simple operation, 

time is short, it is a very effective defrosting method, however it is only limited to 

the air cooler with drain pipe, and the cold temperature is usually above -4 ℃.