1. Vapor Compression Refrigeration Cycle

The four main components of a refrigeration system include: Refrigeration Compressor, Condenser, throttling devices (such as Expansion Valve, etc.), Evaporator. These four main components, together with Refrigerant, form the essential conditions for realizing a refrigeration cycle.

Compressor

Common types of cold storage compressors include piston type, screw type, scroll type, rotary type, etc. The suitable type can be selected according to the scale of the cold storage and refrigeration requirements.

Condenser

Core function: To cool and condense the superheated vapor discharged from the compressor into high-pressure liquid. According to different cooling media, it is mainly divided into two categories:

Water-cooled condenser: Refrigerant vapor condenses inside the shell and outside the tubes, with cooling water flowing through the tubes, usually in a bottom-in, top-out manner. It has a high heat transfer coefficient and good condensation effect, and usually works in conjunction with Water Pump and cooling tower.

Air-cooled condenser: Uses air as the cooling medium, accelerates air flow through fans to enhance heat transfer. It is suitable for scenarios where water supply is difficult or cooling towers are inconvenient to install, with a slightly inferior condensation effect compared to water-cooled condensers.

Throttling Device

Core function: Throttling and pressure reduction to maintain the pressure difference between the condenser and evaporator, so that the refrigerant evaporates and absorbs heat in the evaporator at low pressure (low temperature); meanwhile, it can flexibly adjust the refrigerant flow according to changes in the evaporator's heat load to ensure stable refrigeration effect. Common types of throttling devices: Internal equalizer thermostatic expansion valve, external equalizer thermostatic expansion valve, capillary tube, electronic expansion valve.

Evaporator

The liquid refrigerant after throttling vaporizes and absorbs heat in the evaporator (maintaining low temperature and low pressure), thereby reducing the temperature of the cooled medium to achieve refrigeration. Common types and their features are as follows:

Pipe Coil: Simple structure, easy to manufacture, but with low heat transfer coefficient and difficult oil return.

Air Cooler: Usually non-flooded type, with small liquid charge, easy oil return, low cooling loss and fast cooling speed.

Auxiliary equipment for cold storage systems mainly includes: Oil Separator, Gas-Liquid Separator, Drier Filter, Solenoid Valve, Liquid Receiver, Oil Collector, Intercooler, Evaporating Pressure Regulator. Each device works collaboratively to ensure the stable and efficient operation of the system.

Oil Separator

Function: Installed on the exhaust pipeline, it separates the refrigeration oil mixed in the refrigerant, allowing the refrigeration oil to flow directly back to the compressor crankcase, reducing the amount of refrigeration oil entering the refrigeration system, avoiding impact on the heat transfer effect of Heat Exchanger, and extending the service life of equipment.

Applicable scenarios: Medium and low temperature refrigeration systems, and refrigeration systems with long liquid supply pipes and suction pipes.

Gas-Liquid Separator

Function: Before low-temperature and low-pressure refrigerant gas enters the compressor suction valve, it separates the refrigerant liquid that has not completely evaporated in the evaporator of the refrigeration system, preventing the compressor from wet stroke (liquid slugging) and protecting the compressor from damage.

Applicable scenarios: Refrigeration systems under medium and low temperature conditions.

Drier Filter

Function: Absorbs moisture in liquid refrigerant, filters dirt and impurities in the refrigerant, prevents moisture and impurities from causing blockage of system pipelines and corrosion of components, ensuring smooth flow of refrigerant.

Installation position: Usually installed at the refrigerant outlet of the liquid receiver and water-cooled condenser.

Common types: Mainly divided into three types: moisture-filtering type, impurity-filtering type, and acid-filtering type.

Solenoid Valve

Function: When the compressor stops running, the solenoid valve automatically closes to prevent refrigerant from the high-pressure side entering the low-pressure system; when the compressor restarts, it can avoid liquid slugging caused by system pressure imbalance, protecting the compressor.

Installation position: 100mm to 200mm away from the thermostatic expansion valve.

Liquid Receiver

Function: When refrigeration conditions change or refrigeration capacity is adjusted, it balances and stabilizes the refrigerant flow in the system, ensuring normal and stable operation of the refrigeration unit.

Volume requirement: Its volume should be able to accommodate all refrigerant in the system, with the maximum storage capacity not exceeding 80% of its container volume.

Oil Collector

Function: Mainly used in parallel refrigeration systems, it collects refrigeration oil separated by each oil separator, ensures the normal operation of each oil separator, and returns the collected refrigeration oil to each compressor to maintain the lubrication demand of the compressor.

Evaporating Pressure Regulator

Function: The core is to maintain constant pressure inside the evaporator, and can automatically adjust the opening degree according to changes in the evaporator's load. Since the regulator is equipped with a balanced bellows (bellows area equal to the valve seat area), pressure changes at its outlet will not affect the opening state.

Structural features: Equipped with a Pressure Gauge interface, which can be used to set the required evaporating pressure for precise regulation.

Intercooler

Function: Mainly applied in low-temperature systems of two-stage or multi-stage compression refrigeration cycles, it cools the superheated vapor discharged from the low-pressure stage, stabilizes the intermediate pressure, reduces the system compression ratio, improves refrigeration efficiency, and protects the compressor.