Make the compressor lubricating oil maintain a certain temperature, thereby reducing the proportion of refrigerant dissolved in the oil, the most important thing is to prevent the viscosity of the oil and refrigerant mixture when it is cold to make the compressor start resistance is large, for large units will generally take this method to protect the compressor, and for small units this is not needed, the refrigeration system itself is less refrigerant, high and low pressure difference is small.
