1, refrigeration evaporator surface frost is too thick or too much dust accumulation, heat transfer effect is reduced
Layer is too thick or too much dust caused. As most of the surface temperature of the refrigeration cold storage evaporator is below 0 ℃, and the relative high humidity of the warehouse, the moisture in the air is very easy to frost on the surface of the evaporator, or even ice, affecting the heat transfer effect of the evaporator. In order to prevent the evaporator surface frost layer is too thick, it is necessary to defrost it regularly.
Here are two simple defrosting methods: ① stopping frost. That is, stop the compressor running, open the door to the warehouse, so that the warehouse temperature rises, to be automatically melted frost layer, and then restart the compressor. ② Frost. After moving the goods out of the warehouse, directly with higher temperature tap water to flush the surface of the evaporator tube, so that the frost layer dissolved or fall off. In addition to thick frost will lead to poor heat transfer effect of the evaporator, the evaporator surface is too thick due to long time without cleaning and dust accumulation, its heat transfer efficiency will also be significantly reduced.
2, refrigeration cold storage due to poor thermal insulation or sealing performance, resulting in large cold loss
Poor thermal insulation performance is due to the pipeline, warehouse insulation wall insulation layer thickness is not enough, thermal insulation and thermal insulation effect is poor, it is mainly designed to choose the thickness of the insulation layer is not appropriate or the construction of the insulation material quality is poor. In addition, in the process of construction and use, the insulation material insulation and moisture resistance may be damaged resulting in insulation layer moisture, deformation, or even vesiculation, its thermal insulation and heat preservation ability to decline, the warehouse cold loss increases, refrigeration cold storage library temperature drop significantly slowed down.
Another important reason for the cold loss is the poor sealing performance of the warehouse, there are more hot air from the air leakage into the warehouse. Generally if the sealing strip in the warehouse door or cold storage thermal insulation wall seal appeared at the dew phenomenon, it shows that the seal is not tight. In addition, frequent opening and closing of the warehouse door or more people entering the warehouse together will also increase the cold loss of the warehouse. Should try to avoid opening the door to prevent a lot of hot air into the warehouse. Of course, the warehouse into the inventory frequently or into the stock is too large, the heat load increases dramatically, to cool down to the specified temperature generally need a longer period of time.
3, throttle valve improperly regulated or clogged, refrigerant flow is too large or too small
Throttle valve improperly regulated or blocked, will directly affect the refrigerant flow into the evaporator. When the throttle valve is open too large, the refrigerant flow is large, evaporative pressure and evaporative temperature also rises, the warehouse temperature will slow down the rate of decline; at the same time, when the throttle valve is open too small or clogged, the refrigerant flow is also reduced, the system’s refrigeration capacity is also reduced, the temperature of the warehouse will slow down the same rate of decline.
Generally by observing the evaporation pressure, evaporation temperature and suction pipe frost to determine whether the throttle refrigerant flow is appropriate. Throttle blockage is an important factor affecting the refrigerant flow, causing throttle blockage is the main reason for ice plug and dirty plug.
Ice blockage is due to the drying effect of the dryer is not good, the refrigerant contains water, flow through the throttle valve, the temperature drops to below 0 ℃, the moisture in the refrigerant into ice and blocking the throttle hole; dirty blockage is due to the throttle valve inlet filter mesh on the accumulation of a large number of dirt, refrigerant flow is not smooth, the formation of the blockage.
4, refrigeration compressor efficiency is low, refrigeration capacity can not meet the warehouse load requirements
Refrigeration compressor due to long-term operation, the cylinder liner and piston ring and other components due to severe wear and tear, with increased clearance, sealing performance will decline accordingly, the refrigeration compressor gas transmission coefficient is also reduced, the refrigeration capacity will be reduced. When the cooling capacity is less than the thermal load of the warehouse, it will lead to a slow decline in the temperature of the warehouse.
Compressor can be observed through the compressor suction and discharge pressure roughly determine the refrigeration capacity of the compressor. If the compressor refrigeration capacity decline, the common method is to replace the compressor cylinder liner and piston ring, if the replacement is still not effective, it should consider other factors, and even dismantle the machine overhaul, troubleshooting factors.
5, the evaporator in the presence of more air or refrigeration oil, heat transfer effect decreased
Once the evaporator heat transfer tube attached to the inner surface of the more frozen oil, its heat transfer coefficient will be reduced, the same, if there is more air in the heat transfer tube, the evaporator heat transfer area is reduced, the heat transfer efficiency will also be significantly reduced, the temperature of the storage room to slow down the rate of decline. Therefore, in the daily operation and maintenance, attention should be paid to the timely removal of evaporator heat transfer tube surface oil and discharge the air in the evaporator, in order to improve the heat transfer efficiency of the evaporator.
6, the amount of refrigerant in the system is insufficient, insufficient refrigeration capacity
Insufficient refrigerant circulation is mainly due to two reasons, one is the refrigerant charge is insufficient, at this time, only need to make up for the full amount of refrigerant can be. Another reason is that the system refrigerant leakage is more, in this case, you should first find the leakage point, focusing on the inspection of the pipeline, valve connections, find out the leakage site repair, and then charge the full amount of refrigerant.
Post time: Jun-20-2024
