HIGH EFFICIENCY, LOW CHARGE AMMONIA SOLUTION FOR LOW TEMPERATURE FOOD PROCESSING AND COLD STORAGE APPLICATIONS

摘要

At low evaporating temperatures, refrigeration systems using ammonia are significantly more efficient than systems using other refrigerants. However, it is not desirable to use traditional pumped flooded systems with air evaporators due to the large quantities of ammonia required. DX ammonia refrigeration systems operating at low temperatures tend to have lower evaporating pressures, making them inefficient due to the water content in ammonia. Recent research with the aid of flow visualisation has led to a change in design of low pressure receiver type air evaporators. When combined with a low charge, low pressure receiver system, it has been found that they are more efficient than a traditional pumped flooded system. The added advantage of a low pressure receiver ammonia system is that it lends itself to a very efficient reverse cycle defrosting system, making this system an ideal solution for use in spiral freezers and cold storage applications.