Reasons for the slow temperature drop of the refrigerator

Reasons for the slow temperature drop of the refrigerator

The refrigeration performance of the refrigerator is a major factor in evaluating the quality of the refrigerator, so the temperature of the refrigerator is very important. It is a common phenomenon that the temperature of the refrigerated cabinet does not drop and the drop is slow. This is also a fault that needs to be solved urgently, because if the temperature is not low enough, it will directly affect the preservation of food. Here is a brief analysis of the reasons for the slow drop in cabinet temperature, hoping to bring some help to everyone when using the refrigerator.

　　 1. The refrigerator has a large loss of cooling due to poor heat insulation or sealing performance

　　 Poor thermal insulation performance is due to insufficient insulation thickness of pipes, warehouse insulation walls, etc., and poor thermal insulation and thermal insulation effects. It is mainly caused by improper selection of insulation layer thickness during design or poor quality of insulation materials during construction. In addition, during construction and use, the thermal insulation and moisture-proof performance of the thermal insulation material may be destroyed, causing the insulation layer to be damp, deformed, or even eroded, and its thermal insulation capacity will decrease, and the loss of cold storage capacity will increase, and the temperature drop will be significantly slowed down . Another important reason for the large cold loss is the poor sealing performance of the warehouse, and more hot air invades the warehouse from the leak. Generally, if condensation occurs on the sealing strip of the warehouse door or the seal of the insulation wall of the freezer, it means that the seal is not tight. In addition, frequent opening and closing of the warehouse door or more people entering the warehouse together will increase the cooling capacity loss of the warehouse. Try to avoid opening the warehouse door to prevent a large amount of hot air from entering the warehouse. Of course, when the warehouse stocks frequently or the stock volume is too large, the heat load increases sharply, and it generally takes a long time to cool down to the specified temperature.

　　2. The surface of the evaporator is too thick or dusty, and the heat transfer effect is reduced

　　 Another important reason for the slow decrease of the storage temperature is the low heat transfer efficiency of the evaporator, which is mainly caused by the excessively thick frost layer on the surface of the evaporator or excessive dust accumulation. Since the surface temperature of the evaporator of the freezer is mostly lower than 0℃, and the humidity of the warehouse is relatively high, the moisture in the air is very easy to frost or even freeze on the surface of the evaporator, which affects the heat transfer effect of the evaporator. In order to prevent the frost layer on the surface of the evaporator from being too thick, it needs to be defrosted regularly. Two simpler defrosting methods are introduced below: ① Shut down and defrost. That is, stop the compressor, open the warehouse door, let the warehouse temperature rise, and restart the compressor after the frost layer automatically melts. ② Frost. After removing the goods in the warehouse, directly rinse the surface of the evaporator pipe with hot tap water to dissolve or fall off the frost layer. In addition to excessively thick frosting will lead to poor heat transfer performance of the evaporator, the evaporator surface has too thick dust due to long-term uncleaned, and its heat transfer efficiency will also be significantly reduced.

　　3. There is more air or frozen oil in the evaporator of the refrigerator, and the heat transfer effect is reduced

Once more refrigerant oil is attached to the inner surface of the heat transfer tube of the evaporator, its heat transfer coefficient will decrease. Similarly, if there is more air in the heat transfer tube, the heat transfer area of ​​the evaporator will decrease, and its heat transfer The efficiency will also drop significantly, and the temperature drop of the warehouse will slow down accordingly. Therefore, in daily operation and maintenance, attention should be paid to timely removing the oil on the inner surface of the evaporator heat transfer tube and exhausting the air in the evaporator to improve the heat transfer efficiency of the evaporator.

　　4. The throttle valve is improperly adjusted or blocked, and the refrigerant flow is too large or too small

　　 Improper adjustment or blockage of the throttle valve will directly affect the refrigerant flow into the evaporator. When the throttle valve is opened too large, the refrigerant flow is too large, and the evaporating pressure and evaporating temperature will also increase, and the temperature drop rate of the warehouse will slow down; at the same time, when the throttle valve is opened too small or blocked, the refrigerant The flow rate also decreases, the cooling capacity of the system also decreases, and the temperature drop rate of the warehouse will also slow down. Generally, you can judge whether the throttle valve refrigerant flow is appropriate by observing the evaporating pressure, evaporating temperature, and frosting of the suction pipe. Throttle valve blockage is an important factor affecting refrigerant flow. The main cause of throttle valve blockage is ice blockage and dirty blockage. The ice blockage is due to the poor drying effect of the dryer. The refrigerant contains moisture. When it flows through the throttle valve, the temperature drops below 0℃. The moisture in the refrigerant freezes and blocks the throttle valve hole; Due to the accumulation of more dirt on the filter at the inlet of the throttle valve, the refrigerant flow is not smooth, causing blockage.