Large ice machines will encounter many problems related to temperature changes during maintenance. What are the problems and how to deal with them. Let us understand:
1. Evaporating temperature of big ice block machine:
The evaporating temperature has a great influence on the refrigeration efficiency. When it decreases by 1 degree, it needs to increase the power by 4% to produce the same cooling capacity. Therefore, when conditions permit, appropriately increasing the evaporation temperature is beneficial to improving the cooling efficiency of the air conditioner.
The evaporating temperature of household air conditioners is generally 5-10 degrees lower than the air outlet temperature of the air conditioner. In normal operation, the evaporating temperature is 5-12 degrees, and the outlet temperature is 10-20 degrees.
Blindly lowering the evaporating temperature can cool the temperature difference, but the cooling capacity of the compressor is reduced, so the cooling speed is not necessarily fast. What's more, the lower the evaporation temperature, the lower the refrigeration coefficient, but the load will increase, the operating time will be extended, and the power consumption will increase.
2. Exhaust temperature is too high
The main reasons for the excessively high exhaust temperature are the following: high return air temperature, large heating capacity of the motor, high compression ratio, high condensation pressure, adiabatic index of the refrigerant, and improper refrigerant selection.
3. liquid strike
(1) In order to ensure the safe operation of the compressor and prevent the occurrence of liquid hammer, the suction temperature is required to be higher than the evaporation temperature, that is, it should have a certain degree of superheat.
(2) Avoid too high or too low temperature. If the suction temperature is too high, that is, the overheating is too high, which will cause the compressor discharge temperature to rise. If the suction temperature is too low, it means that the refrigerant is not completely evaporated in the evaporator, which not only reduces the heat exchange efficiency of the evaporator, but the suction of wet steam will also cause compressor liquid hammer. The suction temperature should be 5～10℃ higher than the evaporation temperature under normal circumstances.
4. To low suction temperature:
（1）. The refrigerant charge is too much, which occupies part of the volume in the condenser and increases the condensing pressure, and the liquid entering the evaporator increases accordingly. The liquid in the evaporator cannot be completely vaporized, so that the gas sucked by the compressor contains liquid droplets. In this way, the temperature of the return air duct drops, but the evaporation temperature does not change because the pressure does not drop, and the degree of superheat decreases. Even if the expansion valve is closed, there is no significant improvement.
（2）.The opening of the expansion valve is too large. Because the temperature sensing element is loosely bound, the contact area with the return pipe is small, or the temperature sensing element is not wrapped with insulating material and its wrapping position is wrong, etc., the temperature measured by the temperature sensing element is inaccurate and close to the ambient temperature, causing the expansion valve to operate. The opening degree increases, resulting in excessive liquid supply.
5. High suction temperature:
（1）.The refrigerant charge in the system is insufficient, or the expansion valve opening is too small, resulting in insufficient refrigerant circulation in the system, less refrigerant entering the evaporator, large superheat, and high suction temperature. To
（2）. the expansion valve port filter is blocked, the liquid supply in the evaporator is insufficient, the amount of refrigerant liquid is reduced, and a part of the evaporator is occupied by superheated steam, so the suction temperature increases. To
（3）. The suction temperature is too high due to other reasons, such as poor insulation of the return air pipe or the pipe being too long, which can cause the suction temperature to be too high. Under normal circumstances, the compressor cylinder head should be half cold and half hot.
6. Exhaust temperature is too low
Exhaust pressure is too low. Although the phenomenon is manifested on the high pressure side, the reason is mostly on the low pressure side. The reasons are:
（1）. The expansion valve is blocked by ice or dirty, and the filter is blocked, etc., which will inevitably reduce the suction and discharge pressure; the refrigerant charge is insufficient;
（2）.the expansion valve hole is blocked, the liquid supply is reduced or even stopped, and the suction and exhaust pressures are reduced at this time.