1. The cold storage has a large loss of cold due to poor insulation or sealing performance. The poor insulation performance of the cold storage is due to the insufficient thickness of the insulation layer of the pipeline, the insulation wall of the warehouse, etc., and the poor insulation and thermal insulation effect. It is mainly caused by improper selection of the thickness of the insulation layer during design or poor quality of the insulation material during construction.
In addition, during the construction and use process, the insulation and moisture-proof performance of the insulation material may be destroyed, causing the insulation layer to be damp, deformed, or even rotten, and its insulation and thermal insulation capacity will decrease. The cold loss in the cold storage will increase accordingly, and the temperature drop in the warehouse 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 sealing of the insulation wall of the cold storage, it means that the seal is not tight.
Frequent opening and closing of the warehouse door or more people entering the warehouse will also increase the cold 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 is frequently stocked or the stock volume is too large, the heat load increases sharply, and it usually takes a long time to cool down to the specified temperature.
2. The frost on the surface of the cold storage evaporator is too thick or there is too much dust, and the heat transfer effect is reduced. Another important reason for the slow temperature drop of the cold storage is the low heat transfer efficiency of the evaporator, which is mainly caused by the thick frost layer on the surface of the evaporator or too much dust.
Since the surface temperature of the cold storage evaporator is mostly below 0℃, and the humidity in the warehouse is relatively high, the moisture in the air is easy to frost on the surface of the evaporator, or even freeze, affecting the heat transfer effect of the evaporator.
3. There is more air or refrigeration oil in the cold storage evaporator, and the heat transfer effect is reduced. Once the inner surface of the heat transfer tube of the cold storage evaporator is attached with more refrigeration oil, its heat transfer coefficient will decrease. Similarly, if there is more air in the heat transfer tube, the heat exchange area of the evaporator will decrease, and its heat transfer efficiency will also decrease significantly, and the temperature drop rate of the warehouse will slow down accordingly. Therefore, in daily operation and maintenance, attention should be paid to timely clearing the oil stains 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. Improper adjustment or blockage of the cold storage throttle valve, excessive or too small refrigerant flow Improper adjustment or blockage of the cold storage throttle valve will directly affect the refrigerant flow entering the evaporator. When the throttle valve is opened too much, the refrigerant flow is too large, the evaporation pressure and evaporation 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 little or blocked, the refrigerant flow rate will also decrease, the cooling capacity of the system will also decrease, and the temperature drop rate of the warehouse will also slow down. Generally, the throttle valve refrigerant flow rate can be judged by observing the evaporation pressure, evaporation temperature and frosting of the suction pipe. Throttle valve blockage is an important factor affecting the refrigerant flow rate. The main causes of throttle valve blockage are ice blockage and dirty blockage. Ice blockage is caused by the poor drying effect of the dryer. The refrigerant contains water. When it flows through the throttle valve, the temperature drops below 0℃, and the water in the refrigerant freezes and blocks the throttle valve hole; dirty blockage is caused by the accumulation of more dirt on the filter net at the inlet of the throttle valve, which makes the refrigerant flow poorly and forms a blockage.
5. Insufficient refrigerant in the cold storage system and insufficient refrigeration capacity. There are two main reasons for the insufficient circulation of refrigerant in the cold storage. One is that the refrigerant charge is insufficient. At this time, you only need to add enough refrigerant. Another reason is that there are many refrigerant leaks in the system. In this case, you should first find the leak point, focus on checking the connections of each pipeline and valve, find out the leaking part, and then fill it with enough refrigerant.
6. The compressor is inefficient and the cooling capacity cannot meet the warehouse load requirements. Due to long-term operation of the compressor, the cylinder liner and piston ring and other parts are severely worn, the matching clearance increases, the sealing performance will decrease accordingly, the air transmission coefficient of the compressor will also decrease, and the cooling capacity will decrease. When the cooling capacity is less than the heat load of the warehouse, the warehouse temperature will drop slowly. The refrigeration capacity of the compressor can be roughly judged by observing the suction and exhaust pressure of the compressor. If the refrigeration capacity of the compressor decreases, the common method is to replace the cylinder liner and piston ring of the compressor. If it still does not work after replacement, other factors should be considered, and even the machine should be disassembled for inspection to eliminate the fault factor.
1. The cold storage has a large loss of cold due to poor insulation or sealing performance. The poor insulation performance of the cold storage is due to the insufficient thickness of the insulation layer of the pipeline, the insulation wall of the warehouse, etc., and the poor insulation and thermal insulation effect. It is mainly caused by improper selection of the thickness of the insulation layer during design or poor quality of the insulation material during construction.
In addition, during the construction and use process, the insulation and moisture-proof performance of the insulation material may be destroyed, causing the insulation layer to be damp, deformed, or even rotten, and its insulation and thermal insulation capacity will decrease. The cold loss in the cold storage will increase accordingly, and the temperature drop in the warehouse 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 sealing of the insulation wall of the cold storage, it means that the seal is not tight.
Frequent opening and closing of the warehouse door or more people entering the warehouse will also increase the cold 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 is frequently stocked or the stock volume is too large, the heat load increases sharply, and it usually takes a long time to cool down to the specified temperature.
2. The frost on the surface of the cold storage evaporator is too thick or there is too much dust, and the heat transfer effect is reduced. Another important reason for the slow temperature drop of the cold storage is the low heat transfer efficiency of the evaporator, which is mainly caused by the thick frost layer on the surface of the evaporator or too much dust.
Since the surface temperature of the cold storage evaporator is mostly below 0℃, and the humidity in the warehouse is relatively high, the moisture in the air is easy to frost on the surface of the evaporator, or even freeze, affecting the heat transfer effect of the evaporator.
3. There is more air or refrigeration oil in the cold storage evaporator, and the heat transfer effect is reduced. Once the inner surface of the heat transfer tube of the cold storage evaporator is attached with more refrigeration oil, its heat transfer coefficient will decrease. Similarly, if there is more air in the heat transfer tube, the heat exchange area of the evaporator will decrease, and its heat transfer efficiency will also decrease significantly, and the temperature drop rate of the warehouse will slow down accordingly. Therefore, in daily operation and maintenance, attention should be paid to timely clearing the oil stains 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. Improper adjustment or blockage of the cold storage throttle valve, excessive or too small refrigerant flow Improper adjustment or blockage of the cold storage throttle valve will directly affect the refrigerant flow entering the evaporator. When the throttle valve is opened too much, the refrigerant flow is too large, the evaporation pressure and evaporation 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 little or blocked, the refrigerant flow rate will also decrease, the cooling capacity of the system will also decrease, and the temperature drop rate of the warehouse will also slow down. Generally, the throttle valve refrigerant flow rate can be judged by observing the evaporation pressure, evaporation temperature and frosting of the suction pipe. Throttle valve blockage is an important factor affecting the refrigerant flow rate. The main causes of throttle valve blockage are ice blockage and dirty blockage. Ice blockage is caused by the poor drying effect of the dryer. The refrigerant contains water. When it flows through the throttle valve, the temperature drops below 0℃, and the water in the refrigerant freezes and blocks the throttle valve hole; dirty blockage is caused by the accumulation of more dirt on the filter net at the inlet of the throttle valve, which makes the refrigerant flow poorly and forms a blockage.
5. Insufficient refrigerant in the cold storage system and insufficient refrigeration capacity. There are two main reasons for the insufficient circulation of refrigerant in the cold storage. One is that the refrigerant charge is insufficient. At this time, you only need to add enough refrigerant. Another reason is that there are many refrigerant leaks in the system. In this case, you should first find the leak point, focus on checking the connections of each pipeline and valve, find out the leaking part, and then fill it with enough refrigerant.
6. The compressor is inefficient and the cooling capacity cannot meet the warehouse load requirements. Due to long-term operation of the compressor, the cylinder liner and piston ring and other parts are severely worn, the matching clearance increases, the sealing performance will decrease accordingly, the air transmission coefficient of the compressor will also decrease, and the cooling capacity will decrease. When the cooling capacity is less than the heat load of the warehouse, the warehouse temperature will drop slowly. The refrigeration capacity of the compressor can be roughly judged by observing the suction and exhaust pressure of the compressor. If the refrigeration capacity of the compressor decreases, the common method is to replace the cylinder liner and piston ring of the compressor. If it still does not work after replacement, other factors should be considered, and even the machine should be disassembled for inspection to eliminate the fault factor.
