Refrigeration capacity does not meet the requirements of the warehouse load (low compressor efficiency)
There are two main reasons for the lack of refrigerant round quantity.
① one is not enough refrigerant charge, this time only need to make up for the full amount of refrigerant can be;
② another reason is that the system refrigerant leakage is more, catch this situation, should first find the leak, focusing on the inspection of the pipeline, valve connections, to find out the leakage site repair, and then charge the full amount of refrigerant.
Lack of refrigeration capacity (insufficient amount of refrigerant in the system)
Insufficient refrigerant in the system will directly affect the refrigerant flow into the evaporator.
When the expansion valve opens too far, the expansion valve is improperly regulated or clogged. Refrigerant flow is large, the evaporating pressure and evaporating temperature also rise, the warehouse temperature will slow down the rate of decline; at the same time, when the expansion valve is opened too small or blocked, the refrigerant flow is also reduced, the system’s refrigeration capacity is also reduced, the temperature of the warehouse will also slow down the rate of decline. Generally by observing the evaporation pressure, evaporation temperature and suction pipe frost to determine whether the expansion valve refrigerant flow is appropriate.
Expansion valve clogging is an important factor affecting the refrigerant flow, causing expansion valve clogging is the main reason for ice plugging and dirty plug. Ice blockage is because the drying effect of the dryer is not good, the refrigerant contains water, flow through the expansion valve, the temperature drops to below 0 ℃, the moisture in the refrigerant into ice and block the throttle valve hole; dirty blockage is because of the expansion valve inlet filter mesh contains a lot of dirt, the refrigerant flows smoothly, the formation of the blockage.
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Refrigerant flow is too large or too small (improperly adjusted or clogged expansion valve)
Its heat transfer coefficient will be reduced, once the evaporator heat transfer tube attached to the inner appearance of more refrigeration oil. Similarly, if there is more air in the heat transfer tube, the heat transfer area of the evaporator is reduced, and its heat transfer efficiency will be significantly reduced, and the rate of temperature drop in the storage room is slowed down. Therefore, daily operation and maintenance, should pay attention to timely removal of evaporator heat transfer tube inside the appearance of oil and discharge the air in the evaporator, in order to improve the heat transfer efficiency of the evaporator.
Heat transfer effect decreases (evaporator exists in more air or refrigeration oil)
This is mainly due to the evaporator exterior frost layer is too thick or too much dust caused by the cold storage evaporator exterior temperature is mostly lower than 0 ℃, resulting in a slow decline in the temperature of the library is another important reason for the evaporator heat transfer efficiency is low. The warehouse humidity is relatively high, the moisture in the air is very easy in the evaporator exterior frost, or even ice, affecting the heat transfer effect of the evaporator. In order to prevent the exterior of the evaporator frost layer is too thick, need to defrost it on a regular basis.
The following are two simple defrosting methods:
① stop 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 flushing: the goods out of the warehouse, directly with a higher temperature of tap water to flush the surface of the evaporator tube, so that the frost layer dissolved or fall off. In addition to the thick frost will lead to the evaporator heat transfer effect is not good, the evaporator appearance due to the temporary cleaning and dust accumulation is too thick, its heat transfer efficiency will also be significantly reduced.
Decrease in heat transfer effect (too thick frost or excessive accumulation of dust on the exterior of the evaporator)
Poor thermal insulation and heat preservation effect, poor thermal insulation function is because of the pipeline, warehouse insulation wall, etc., the thickness of the insulation layer is not enough. Mainly is the design of the thermal insulation layer thickness selection is not appropriate or construction of the thermal insulation material quality is poor.
In addition, the construction and use process, the insulation material insulation moisture-proof function may be damaged resulting in insulation layer moisture, deformation, or even rotten, its thermal insulation ability to decline, the library of cold loss increases, the library temperature drop significantly slowed down.
Another important reason for the cold loss is the poor sealing function 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 wall sealing the phenomenon of condensation, it shows that the seal is not tight.
In addition, frequent opening and closing of the warehouse door or more people together into the warehouse, will also increase the warehouse cold loss. Should try to prevent the opening of the warehouse door to prevent a large amount of hot air into the warehouse. Of course, the warehouse into the inventory frequently or when the amount of goods is too large, the heat load increases sharply, to cool down to the delineation of the temperature generally takes a long time.
Resulting in a large loss of cold (cold storage because of poor insulation or sealing function)
Cylinder liners and piston rings and other parts because of severe wear and tear, the compressor because of temporary operation. The fit gap increases, the sealing function will decline accordingly, the compressor gas transmission coefficient is also reduced, the refrigeration capacity will be reduced. When the refrigeration 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 inspection, troubleshooting factors.
Post time: Aug-08-2024