In the physics class, we will tell us that the frost is a bad conductor of heat, the thermal conductivity is only 0.58W/(m·°C), and the thermal conductivity is 372.16W/(m·°C) and 203.516W/(m·°C). The coefficient is much smaller. The evaporator indicates that frosting greatly reduces its heat exchange capacity and seriously affects the refrigeration performance of the refrigeration system. When the thickness of the frost layer on the evaporator reaches 10 mm, the heat transfer efficiency will drop by more than 30%, causing the compressor to run for a long time, increasing the power consumption, and even causing the compressor to malfunction. Therefore, timely defrosting is a necessary measure to ensure the normal and safe operation of the refrigerator.
(1) artificial cream
Artificial defrosting creams are mostly used in single-door direct-cooling refrigerators and double-door direct-cooling refrigerators without electric heating defrosting devices. When the thickness of the frost indicated by the refrigerator evaporator reaches 4-6 mm, turn the thermostat knob to the stop position (ie 0 or OFF position), or unplug the refrigerator to stop the compressor. After the defrosting is over, adjust the thermostat to the normal working position or plug the plug back in. Although artificial defrosting has the advantages of simple operation and power saving, it is inconvenient. It is necessary to observe the defrosting condition at any time. Once the defrosting is over, and the compressor is not restored in time, the temperature inside the box will rise, resulting in restarting. Electricity consumption increased.
(2) Semi-automatic defrost
It is generally used on a two-door direct-cooling refrigerator equipped with a semi-automatic frost button or an electric heating defrosting device. When the surface layer of the evaporator reaches 4-6 mm, press the defrosting button of the semi-automatic frost thermostat to cut off the power of the compressor motor to stop the compressor. This defrosting method can take the form of natural defrosting or electric heating cream. When the frost layer on the surface of the evaporator is completely melted, the surface temperature of the evaporator reaches 4 - 4 ° C, the temperature inside the chamber is about 10 ° C, and the defrost button of the semi-automatic frost thermostat automatically jumps to turn on the compressor motor. The power supply returns the compressor to work. The advantage of this defrosting method is that the structure is simple and the action is reliable, but the defrosting begins to require manual operation.
(3) Automatic defrost
Applied to the intercooled refrigerator . The feature is that the defrosting process can not only automatically time, but also automatically stop the refrigeration compressor during defrosting, and simultaneously turn on the defrosting electric heating wire circuit. After the defrosting reaches the requirement, the defrosting process can be automatically stopped to resume the work of the refrigeration compressor.
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