Due to the changeable environment of the cold room and the harsh operating conditions, with the complex structure of the refrigeration system, its operation failures are frequent, which not only affects the quality of goods, but also wastes a lot of electricity and even causes safety accidents. Let’s discuss the cold room common faults and troubleshooting tips.
1, The temperature of the cold room cannot be dropped down
(1) Insufficient cooling capacity of the compressor: The compressor is the “heart” of the cold room refrigeration system, and its displacement directly determines the cooling capacity. When the displacement decreases due to compressor piston ring wear, valve leakage, lubricating oil deterioration, etc., the temperature of the cold room cannot be dropped down.
(2) Poor heat exchanger of the condenser: The condenser is a key component for the refrigerant to release heat and condense from gas to liquid. If the surface of the condenser is covered with dust, the pipeline is blocked, the cooling fan fails, etc., it will reduce its heat exchanger efficiency.
(3) Severe ice frost on the evaporator: If there is too much ice frost on the surface of the evaporator, it will hinder the refrigerant from absorbing heat and affect the cooling of the cold room. Common causes of evaporator frost include failure of the defrost device, excessive humidity in the cold room, and refrigerant liquid shock (liquid refrigerant directly enters the compressor).
(4) Poor insulation of the cold room: If the thickness of the insulation panels is insufficient, or there are defects such as damage and leakage, the external heat will continue to penetrate, increase the load of the refrigeration system, and make it difficult to reduce the cold room temperature.
(5) Open the cold room doros too frequently: Every time open the cold room door , a large amount of external hot air rushes in, which not only increases the sensible heat load, but also brings a large amount of water vapor, increases the humidity in the cold room, aggravates the ice frosting of the evaporator, and affects the refrigeration effect.
The troubleshooting tips:
(1) Check the compressor timely, replace the piston ring and valve if necessary, and replace the filter screen and flush the lubrication system in time to restore the compressor displacement.
(2) Clean the condenser regularly, clear the blocked pipes, repair the cooling fan, improve the heat dissipation efficiency of the condenser, and ensure that the refrigerant is fully condensed.
(3) Check the defrost device and repair the fault in time; reasonably set the defrost cycle and duration to avoid excessive frosting of the evaporator. Control the relative humidity in the cold room at 80-85% to reduce frosting of the evaporator.
(4) Select materials such as polyurethane with low thermal conductivity and good aging resistance, increase the thickness of the insulation panels, and repair damage and leakage in time to reduce cooling loss.
(5) Optimize the management of the cold room door, shorten the door opening time, and reduce the frequency. Air curtains can be used to block the entry of hot air from the outside. If conditions permit, it is recommended to set up an airlock room to further isolate the outside air.
2, Cold room discharge pressure is too high or too low
(I) Common faults and troubleshooting tips for excessively high discharge pressure in cold room
(1) Poor heat dissipation of the condenser: As mentioned above, when dust accumulates on the surface of the condenser and the pipeline is blocked, the condensation pressure will increase, and the discharge pressure will increase accordingly. The condenser needs to be cleaned and the pipeline unblocked in time.
(2) Excessive refrigerant: Too much refrigerant in the system will increase the condenser pressure and the discharge pressure will increase accordingly. The excess refrigerant needs to be released and restored to the appropriate filling amount.
(3) Non-condensable gas enters the system: If the system vacuum is not enough, non-condensable gases such as air and water vapor will mix in and gather in the condenser, causing the condensation pressure to increase. It is necessary to re-evacuate and exhaust the non-condensable gas.
(II) Common faults and troubleshooting tips for excessively low discharge pressure in cold room
(1) Refrigerant leakage: If there are defects such as cracks and cracks in the refrigerant pipeline, the refrigerant will leak in large quantities, causing the system pressure to drop. It is necessary to check the pipeline, locate the leak point and repair it, and refill the refrigerant to the appropriate amount.
(2) Poor oil return from the evaporator: When the compressor is running, the lubricating oil will enter the evaporator along with the refrigerant and needs to be returned to the compressor regularly. If the oil return pipe is blocked and too much oil accumulates, it will affect the heat exchange of the evaporator, causing the evaporation pressure to drop and the discharge pressure to drop accordingly The oil return pipe needs to be cleared in time.
(3) The opening of the thermal expansion valve is too small: The thermal expansion valve is a throttling device that regulates the flow of refrigerant entering the evaporator. If the temperature sensor is not installed properly, the valve opening is too small, which will reduce the refrigerant entering the evaporator and reduce the evaporation pressure. The position of the temperature sensor needs to be adjusted to restore the normal opening.
