Investigation of air cooler fan start-up delay in liquid refrigerant defrosting system

To prevent problems concerning rapid rise in cold-storage temperature and severe frosting of the compressor inlet in liquid refrigerant defrosting systems (LRDS), a shutter has been installed upstream of the air cooler as well as the motor damper installed downstream. It is also proposed that the air-cooler fan is switched into operation delay after defrosting. Experimental results demonstrate that the best time to switch the fan into operation post defrosting is when the enclosed-space temperature of the air cooler falls in line with the cold storage temperature. Time delays for the fan were set as 8.6 min, 8.8 min, and 8.9 min corresponding to frost mass values of 1 kg, 2 kg, and 3 kg, respectively. Through use of the proposed technique, the observed increase in cold-storage temperature was controlled within 5 degrees C. In addition, gas return temperature of the compressor was observed to be greater compared to that of the air cooler; the compressor, therefore, utilized the available superheat to prevent the occurrence of wet compression.