Cold Storage Daily Operation and Maintenance

According to different temperature and humidity requirements for stored items, processing methods and usage properties, cold storages can be roughly divided into the following types: vegetable preservation cold storage, frozen goods cold storage, cooling cold storage, freezing cold storage, ice storage, process cold storage, etc.
Cooling preservation cold storage:
Operating temperature: 0 - 4°C; mainly used for fresh-keeping storage of foods such as fruits, vegetables, meat, seafood, fresh eggs, dairy products, tea, etc., and refrigeration of beer and beverages.
Frozen goods cold storage:
Operating temperature: -22 - -18°C; mainly used for refrigeration of frozen goods such as meat and seafood.
Process cold storage: The operating temperature is determined according to the usage purpose and process characteristics.
Components of cold storage: enclosure structure; compression refrigeration unit; solenoid valve, sight glass; expansion valve; evaporator (air cooler); system connection pipes; electrical control system (fully automatic computer control cabinet); refrigeration auxiliary equipment (such as cooling tower, pressure tank, water pump, etc.

).
Enclosure structure:
Cold storages are divided into civil construction type and prefabricated type according to structural form.
Civil construction cold storage: mainly composed of enclosure structure and load-bearing structure. In addition to being able to withstand external wind and rain, its external enclosure structure must also have heat insulation and moisture-proof functions. Therefore, during the construction process of civil construction cold storages, there are more construction procedures, large workloads and long construction periods.
Application: Due to its good heat preservation effect and relatively less influence from the outside, it is widely used in some large fruit and vegetable production and wholesale bases and some meat and poultry processing factories.
Prefabricated cold storage: The cold storage body is mainly composed of insulation boards. The insulation boards of cold storages are all sandwich panels. The inner and outer surfaces of sandwich panels are mostly glass steel plates, color steel plates, and there are also aluminum alloy plates or other plastic plates. The sandwich insulation materials are mostly rigid polyurethane or polystyrene foam plastics.
Application: Prefabricated cold storages are increasingly widely used in commerce due to their characteristics of simple structure, convenient installation, short construction period, light weight, high strength and beautiful appearance, especially in hotels, restaurants, vegetable markets and commercial food circulation fields.
Compression refrigeration unit:
According to different cooling methods of condensers, it is divided into: air-cooled unit; water-cooled unit.

Components of compression refrigeration unit: compressor, condenser, receiver, drying filter, pressure controller, high and low pressure gauges, connection pipes.
Compressor, the heart of the refrigeration system.
Continuously extract the refrigerant vapor that has completed the heat absorption process and vaporized in the evaporator, maintaining the low temperature and low pressure in the evaporator.
Continuously compress the low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigeration gas, providing power for the refrigeration cycle, thereby realizing the refrigeration cycle of compression - condensation - expansion - evaporation (heat absorption) - compression.
Types: semi-hermetic, fully hermetic, open type; rotor, scroll, piston, screw.
Semi-hermetic piston compressor:
Note: The plastic cap cannot be lost. In case of an oil pressure alarm fault, the oil pressure button should be reset after troubleshooting.
Fully hermetic scroll compressor:
Condenser:
Function of condenser - heat exchange equipment.
Transfer the heat of the high-temperature and high-pressure refrigerant vapor from the compressor to the surrounding medium - water or air, and cool it into a low-temperature and high-pressure liquid. It is a necessary equipment for outputting heat to the outside of the system.
Types of condensers:
Air-cooled type (referred to as air-cooled or air-cooled type), water-cooled type (referred to as water-cooled type), evaporative type.
Receiver:
A container for storing and supplying high-pressure liquid refrigerant. Store the liquid refrigerant from the condenser and adjust and stabilize the circulation amount of the refrigerant to adapt to changes in working conditions.
Usually installed behind the condenser (air-cooled unit). Water-cooled units have liquid storage functions and generally do not install receivers.
Drying filter:
Remove moisture and dirt from the system to prevent ice blockage or dirt blockage in the system. Purification equipment for refrigeration systems.
Pressure controller:
Control high and low pressures. When the exhaust pressure is too high or the suction pressure is too low, the controller will act immediately to cut off the pressure control circuit and stop the compressor.
Note: In case of excessive high pressure, after troubleshooting, and with the consent of technical personnel before starting up, reset the manual reset button.
Pressure gauge:
Pressure gauge: Displays high pressure and low pressure values.
Difference between high and low pressure gauges: High pressure gauge range (-0.1 - 3.8); low pressure gauge range (-0.1 - 1.8).
Units of pressure gauge readings: MPa, kgf/cm², Psi; 1MPa≈10 kgf/cm² = 145Psi; Equipment managers should be able to correctly read its pressure value.
Solenoid valve and sight glass:
Function of solenoid valve: Control the flow of refrigerant to cut off or open the liquid supply to the system.
Function of sight glass: The condition of the refrigerant in the liquid pipeline and the water content of the refrigerant.
Thermal expansion valve:
Function: