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Common problems and solutions of refrigerator unit
Jan 21, 2021

1.On the definition of evaporation temperature, condensation temperature, re cooling temperature and intermediate temperature:

(1)what is evaporation temperature? 
A: the temperature when the refrigerant in the evaporator boils and vaporizes under a certain pressure is called the evaporation temperature. 
(2)What is condensation temperature? 
A: the temperature at which the gas refrigerant in the condenser condenses into liquid under a certain pressure is called the condensation temperature. 
(3)What is the re cooling (or subcooling) temperature? 
A: the liquid refrigerant after condensation is cooled to a temperature lower than the condensation temperature under high temperature and high pressure, which is called the recooling temperature (or supercooling temperature). 
(4)What is the intermediate temperature?
 A: the saturation temperature of refrigerant in intercooler under intermediate pressure (P2) is called intermediate temperature. 

2.About the definition of the suction temperature and discharge temperature of the compressor: 
(1)what is the suction temperature of the compressor?
 A: the suction temperature of the compressor can be measured from the thermometer in front of the suction valve of the compressor, Generally, the suction temperature is higher than the evaporation temperature, and the difference depends on the length of the return pipe, the insulation condition of the pipe and the outlet temperature of the evaporator. Generally, it should be 5 ~ 10 ℃ higher than the evaporation temperature (called superheat).
(2)What is the discharge temperature of the compressor? 
A: the discharge temperature of the compressor can be measured by the thermometer on the discharge pipeline. The exhaust temperature is directly proportional to the pressure ratio (PK / P0) and the suction temperature. If the superheat of suction is higher and the pressure ratio is higher, the exhaust temperature will be higher. Otherwise, on the contrary, the exhaust pressure is slightly higher than the condensation pressure. 

3.What is the reason for the high exhaust pressure?
(1)There are many mixed gases in the high-pressure part of the system and the unit. Elimination method: stop the compressor operation, start the cooling water pump for circulation, open the vent valve to 1 / 5 ~ 1 / 6 circle, check the pressure gauge reading at any time (ensure the accuracy of the pressure gauge, refer to the corresponding pressure and temperature of the thermal property table), and the vent time depends on the pressure close to the value after discharge.
(2)Condenser heat exchange tube scaling and debris removal method: remove the condenser cover on both sides. A. Rinse with high pressure water gun. B. Please deal with it by professional cleaning company. C. Use cloth strips to wipe back and forth. 
(3)The condenser accumulates too much liquid and oil. The elimination method is: A. fill too much refrigerant and discharge or discharge into another container. B. Check whether the outlet valve and balance valve are all opened (check if the valve head falls off if necessary). C. Drain the excess oil. 
(4)Condenser inlet and outlet pipe lead pad damage caused by cooling water short-circuit cycle elimination method: remove the cover, remove the lead part rust, replace the rubber pad. 
(5)The inlet temperature of cooling water exceeds the design requirements. Elimination method: clean up the dirt of cooling water tower, especially the water distributor and packing are evenly distributed and whether the inlet is blocked by foreign matters. 
(6)Elimination methods for insufficient cooling water flow: (the water temperature difference between the inlet and outlet of condenser exceeds the requirements) whether the mechanical wear in the water pump is too large or the foreign matter is blocked, whether the water valve, check valve and filter screen are abnormal, whether the head meets the requirements, and whether the pipeline direction and specification meet the requirements. 

4.The suction temperature of the compressor is higher than the evaporation temperature (higher than the specified value): Troubleshooting: (1) insufficient refrigerant in the system: Supplement refrigerant. (2) Insufficient refrigerant in evaporator: open the throttle valve. (3) If the water content exceeds the specification, check the water content. (4) Small opening of control valve, small liquid supply: increase the liquid supply. (5) The insulation layer of the low pressure pipeline of the refrigeration system is not good: check the insulation layer and replace the insulation material if necessary. 

5. Compressor suction pressure is too low Troubleshooting: compressor suction pressure is too low: Troubleshooting: (1) liquid throttle valve or suction filter blockage: disassembly inspection and cleaning. (2) Insufficient refrigerant in the system: replenish refrigerant. (3) Insufficient refrigerant in evaporator: open the throttle valve. (4) There is too much oil in the system: find out the oil accumulated in the system and let it out.
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