Transport Refrigeration & Compressor cooling

Transport Refrigeration

Truck and trailer refrigeration is an increasingly important segnent of the refrigeration industry. Despite the fact that transport applications face many iperating problems peculiar to theyr unage, there exists very little aplication data pertaining to this field.

Many compressor failures in transport refrigeration unage are the result of system malfunction rather than the result of mechanical wear. It is clear that substantial savings in operating cost, and tremendous improvements in unit perfonmance and life would be possible if the causes of compressor failure could be removed. Primarily the problem boils down to one of making sure that the compressor has adequate lubrication at all times.

Part of the problem of identifying the cause of failure stems from the fact that far too few users realize that ultimate failure of a compressor resulting from lack of lubrication frequently takes place at a time when there is an adequate supply of oil in the crankcase. This is due to continued deterioration of the moving parts resulting from the original or repeated damage in the past. It is not uncommon for a damaged compressor to operate satisfactorily all winter and then fail in the spring when subjeted to heavier loads.

Another source of field problems is the fact that many units are installed by personnel who may not have adequate training, equipment, or experience. Often units, particularly those in common carrier service, may be serviced in emergencies by servicemen not familiar with the unit, or indeed, with transport refrigeration generally.

Because of the intallation and service hazards, it is extremely important that the unit be properly designed and applied to minimize, and if possible, prevent service problems.


Compressor cooling

Air-cooled motor-compressors must have a sufficient quantity of air passing aver the compressor body fot motor cooling. Refrigerant-cooled motor-compressors are cooled adequately by the refrigerant vapor at evaporating temperatures above 0° F. saturation, but at evaporating temperatures below 0° F. additional motor cooling by means of air flow in necessary.

Normally the condenser fan if located so that it discharges on the compressor will provide satisfactory cooling. For proper cooling, the fan must discharge air directly against the compressor. The compressor cannot be adequately cooled by air pulled through a compartment in which the compressor is located. If the compresor is not located in the condenser discharge air stream, adequate air circulation must be provided by an auxiliary fan.