The defrosting of air source heat pump supplying hot water was discussed.

It is found that there are much potential on energy saving in air curtain speed,defrosting frequency,control of dew eliminating tube,etc based on the survey and testing about refrigerated showcases at several supermarkets in Xiamen city.

A simple model to calculate the defrosting electrical energy input and the ways to optimize the air cooler s electro-thermal defrosting system;

Based on the defrosting principles of frost-free refrigerator-freezers evaporator, this paper presented improved design scheme of defrosting system, including aluminum tube conducting defroster being converted into quartz tube radiating defroster and removing thermostat holddown groove.

The start of defrosting of Air-cooled heat pump is usually controlled by the temperature of the surface of fin-tube exchanger.

Based on the theory and experiment research of the characteristic of the refrigerated vertical open display cabinets, the method of reasonably select the main structural parameters including air supply velocity,evaporator structure and defrost cycle etc were discussed.

According to the meteorological observation in Minqin Desert Control Experiment Station,variations of frost-free period,low temperature in spring and frozen earth were analyzed.

Through comparison between several kinds of thermal indexes and analysis of China s climate characteristics,frost-free period is considered to be a proper thermal index of climatic zoning for grapevine in China.