The reason of cold room evaporation temperature is too low and the solution:

1. The evaporator is too small

Design problem, or the actual products type is different from the design plan, and the heat load increases. For example, the cold storage of apples is intended to be used for storage instead of garlic sprouts. Since the harvest time of garlic sprouts in a production area is only a few days, it is impossible to achieve a daily purchase volume of 5% to 15% of the storage capacity as that of Apple, instead of filling up 3-5 days. Therefore, if the temperature should be lowered to the proper storage temperature in time, it can only be achieved by lowering the evaporation temperature. Increase evaporator evaporation area or replace evaporator.

2. The compressor capacity is too large

When the cold storage load was reduced, the energy of the compressor was not reduced in time. The compressor of the cold storage is matched according to the maximum load of the refrigeration system, At most times, the load of the compressor is less than 50%. When the room temperature is reduced to a suitable storage temperature, the system load is greatly reduced. If a large machine is still turned on, a large horse-drawn cart is formed, and the temperature difference increases, and the power consumption increases. The number of compressors to be turned on or the number of cylinders to be operated should be reduced according to changes of cold storage load.

3. The evaporator  not defrosting in time

The frosting of the evaporator coil causes the heat transfer coefficient to become smaller, the thermal resistance increases, the heat transfer effect is reduced, and the evaporation amount of the refrigerant is reduced. Under the condition that the compressor energy is constant, the evaporation pressure of the system will decrease, and the corresponding Evaporation temperature decreases, so should defrost in time.

4. Lubricating oil in evaporator

The lubricating oil in the evaporator will form a layer of oil film on the wall of the evaporating coil, which will also reduce the heat transfer coefficient, increase the thermal resistance, reduce the heat transfer effect, reduce the evaporation amount of the refrigerant, and cause the evaporation pressure of the system to decrease. The corresponding evaporation temperature is reduced, so the system oil should be drained in time.

5. The expansion valve is opening too small

When the expansion valve is opened too small, the amount of liquid supplied by the system is small. Under the condition that the energy of the compressor is not changed, the evaporation pressure is reduced, causing the evaporation temperature to decrease, and the opening degree of the expansion valve should be increased.