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The reason that cold storage is not cooling
Apr 26, 2017

A common phenomenon when the cold storage temperature does not drop down and fall slowly, now down to simple analysis of the reasons of slow temperature:

1, cold storage due to poor insulation or sealing performance, resulting in a large amount of cold loss

Heat insulation performance is poor because of the thickness of the insulation layer, heat insulation wall pipe warehouse is insufficient, heat insulation effect, it is mainly the thickness of the insulation layer design or construction of improper selection of insulation material caused by poor quality. In addition, in the process of construction, thermal insulation materials insulation moisture-proof performance may be caused by the destruction of insulation damp, deformation, and even erosion, its insulation ability, anti cold base loss increases, temperature decline slowed down significantly. Another important reason leading to the loss of cold is the poor performance of the warehouse, there are more hot air from leaking into the warehouse. In general, if the seal in the warehouse door or cold insulation wall seal appeared condensation phenomenon, indicating that the seal is not tight. In addition, the frequent switch door or more people to enter the warehouse warehouse, will increase the cooling capacity of the warehouse. We should try to avoid open doors, to prevent a lot of hot air into the warehouse. Of course, when the inventory is too large or the stock is too large, the heat load increases sharply, it takes a long time to cool down to the required temperature.

2, evaporator surface is too thick or too much dust, heat transfer effect

Temperature drop leads to another important reason is the slow evaporator heat transfer efficiency is low, which is mainly due to the evaporator surface frost layer is too thick or dust caused by too much. Because the surface temperature of the cold storage evaporator is mostly lower than 0 DEG C, and the humidity of the warehouse is relatively high, the moisture in the air is easy to frost on the evaporator surface and even freeze, which affects the heat transfer effect of the evaporator. In order to prevent the evaporator surface frost layer is too thick, the need for regular defrost. The following is a brief introduction of two kinds of defrosting method: stop defrosting. To stop the operation of the compressor, open the warehouse door, let the temperature rise, the automatic defrosting layer, and then restart the compressor. Frost strike. When the goods in the warehouse are moved out, the surface of the evaporator pipe is directly washed with a high temperature tap water to make the frost layer dissolve or fall off. In addition to the excessive thickness of the evaporator will lead to poor heat transfer effect, the surface of the evaporator for a long time without cleaning and excessive dust accumulation, the heat transfer efficiency will be significantly reduced.

3, there are more air or refrigerant oil in the evaporator, the heat transfer effect decreased

Once the evaporator heat transfer tube attached to the surface of oil more, the heat transfer coefficient will decrease, the same, if there are more air in the heat pipe, the heat exchange area of the evaporator is reduced, the heat transfer efficiency will be significantly decreased, temperature drop speed will slow down. Therefore, in the daily operation and maintenance, attention should be paid to the timely removal of the evaporator heat transfer tube surface oil and discharge the air inside the evaporator, in order to improve the heat transfer efficiency of the evaporator.

4, throttle adjustment inappropriate or blocked, refrigerant flow is too large or too small

Improper throttle regulation or blockage will directly affect the flow of refrigerant into the evaporator. When the throttle opening is too high, the refrigerant flow is too large, the evaporation pressure and evaporation temperature, storage temperature will slow down; at the same time, when the throttle valve through a small opening or blockage, the refrigerant flow is reduced, the cooling capacity decreases, the real temperature drop speed of the same library will slow down. It is generally possible to determine the flow rate of the refrigerant by observing the evaporation pressure, the evaporation temperature and the frost formation of the suction pipe. Throttle blockage is an important factor that affects the flow rate of refrigerant. The main cause of throttle blockage is ice jam and dirty plugging. Ice jam is due to poor performance of the dryer, containing water in the refrigerant flowing through the throttle valve, when the temperature is below 0 DEG C, the water freezes and refrigerant throttle valve plug hole; a dirty block is due to the throttle valve inlet filter to accumulate more dirt, refrigerant circulation, plug formation.

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