Cold temperatures slow down and fall is no less than the more common phenomenon. Now cold storage temperature drop causes of slow brief analysis, hope to give cold storage peer friends work to bring a little help.
1, cold storage due to poor insulation or sealing performance, resulting in great loss of cooling capacity
Cold storage insulation performance difference is due to the pipeline, warehouse walls and other heat insulation layer thickness is not enough, poor insulation and insulation effect, it is mainly the poor quality of insulation materials when designing insulation layer thickness improper selection or construction caused. In addition, the construction process, use, moisture-proof insulation performance of insulation materials may be destroyed cause insulation damp, deformation, or even erosion, its insulation capacity decreased, the amount of loss of the library against the cold increases, the storage temperature drops significantly slowed . Another important reason is the loss of large cold warehouse sealing performance is poor, there are more hot air intrusion from leaks at the Treasury. Usually if the library door seal or cold seal appeared insulating wall condensation, then there Mifengbuyan secret. In addition, frequent switching library door or more people went into the Treasury, the Treasury will increase the cooling capacity loss. Open the doors should be avoided to prevent a lot of hot air into the coffers. Of course, the Treasury into inventory frequently or purchase amount is too large, the heat load increases sharply, to lower the temperature to a predetermined temperature generally takes a long time.
2, cold storage evaporator frosting is too thick or too much dust, heat transfer effect is reduced
Cold temperatures slow decline Another important reason is the low efficiency of the evaporator heat transfer, mainly due to the evaporator surface frost layer is too thick or too much dust caused. Since the surface temperature of the cold storage evaporator mostly below 0 ℃, while the Treasury relatively high humidity, moisture in the air easily in the evaporator surface frost, ice and even affect the heat transfer effect evaporator. In order to prevent the evaporator surface frost layer is too thick, you need to defrost it regularly. Here are two simple defrosting method: ① stop defrost. Stop operation of the compressor, open the library door, allowing the storage temperature to rise, until the frost melts automatically, and then restart the compressor. ② red cream. After unloading the cargo warehouse directly rinsed with high temperature water discharge tube evaporator surface, so that the frost layer is dissolved or off. In addition to the frosting is too thick will result in poor heat transfer effect evaporator, the evaporator surface due to long outstanding cleaning and dust is too thick, the heat transfer efficiency will be significantly decreased.
3, there is a cold storage evaporator more air or frozen oil, heat transfer effect is reduced
Once the cold evaporator heat transfer tube inner surface attached more refrigeration oil, the heat transfer coefficient will be reduced. Similarly, if there is more air, heat transfer tube evaporator heat transfer area decreases, its mass thermal efficiency will be significantly decreased, the temperature drop rate on the Treasury subsequently slowed. Thus, in the daily operation and maintenance, attention should be promptly removed in the evaporator heat transfer tube surface oil and exhaust air in the evaporator, the evaporator in order to improve heat transfer efficiency.
4, cold storage throttle improperly adjusted or blocked, the refrigerant flow is too small or too large
Cold throttle improperly adjusted or blocked, will directly affect the refrigerant into the evaporator flow rate. When the throttle valve opening too large, the refrigerant flow rate is too large, the evaporation pressure and evaporation temperature also increased, the Treasury temperature rate of decline will slow; the same time, or when the throttle valve opening is too small blockage, the refrigerant traffic is also reduced, capacity of the system is also decreased, the Treasury will also slow the rate of temperature decrease. Usually by observing the evaporation pressure, temperature and evaporation frost situation to determine the intake pipe throttle the refrigerant flow is appropriate. Throttle valve blockage is an important factor affecting the flow of refrigerant, the main cause of the throttle valve is clogged ice blocking and fouling. Ice block is due to poor drying effect of the dryer, the refrigerant contains water that flows through the throttle valve, the temperature dropped below 0 ℃, the refrigerant in the water into ice clogging the throttle bore; fouling is Since the throttle valve inlet filter medium accumulated more dirt, refrigerant circulation by the formation of blockages.
5, the amount of refrigerant cold storage system, insufficient cooling capacity
Cold refrigerant circulation amount insufficient for two main reasons, one is insufficient refrigerant charge fluence, at this time, just make up a sufficient amount of refrigerant into it. Another reason is that the system refrigerant leak more, encounter this situation, you should find the leak, check the focus of pipes, valves connections, find the leak site repair, and then filled with a sufficient amount of refrigerant.
6, lower compressor efficiency, cooling capacity can not meet the load requirements of the Treasury
Due to long-term operation of the compressor, cylinder liners and piston rings and other components due to wear serious, with the gap increases, the sealing performance will decrease, gas transmission coefficient of the compressor is also reduced, the cooling capacity will be reduced. When the cooling capacity of the heat load is less than the Treasury, the Treasury will cause the temperature drops slowly. By observing the compressor suction and discharge pressure of the compressor cooling capacity is determined substantially. If the compressor cooling capacity decreased, the commonly used method is to replace the compressor cylinder liners and piston rings, replace if still not works, it should consider factors other aspects, even disassemble maintenance, troubleshooting factors.