DC-2796 (RP-193) -- Energy Considerations in Hot-Gas Defrosting of Industrial Refrigeration Coils PDF

One of the popular methods of defrosting industrial refrigeration coils is through the use of high-pressure gas from the compressor discharge or the high-pressure receiver. The defrost process is now one of the numerous targets for energy conservation in the operation of refrigeration plants. Laboratory tests of an R-22 system and field tests of an ammonia system have identified sorry features that could reduce the energy requirements associated with hot-gas defrost, namely (1) the minimum hot-gas pressures that still achieve satisfactory defrost, (2) the method of draining condensed liquid refrigerant from the coil, and (3) the crucial nature of the point at which to terminate defrost. The tests show that pressure differences across the coil lover than typically employed will achieve a satisfactory defrost, and that the control of the drainage should eliminate liquid from the coil as rapidly as possible but then prevent vapor from passing back to the suction line.