Classification by Core Refrigeration Principle
Vapor-Compression Refrigeration
Currently the most widely used mainstream method. A compressor raises the refrigerant to a high-temperature, high-pressure state; after dissipating heat and liquefying in the condenser, the refrigerant evaporates in the evaporator to absorb heat and lower the temperature. This technology is mature and stable, suitable for the vast majority of commercial cold storage applications.
Absorption Refrigeration
Utilizes the chemical reaction between a refrigerant and an absorbent to complete the refrigeration cycle. It can be driven by low-grade heat sources such as waste heat. It features low noise and few moving parts, making it suitable for remote areas or facilities with abundant industrial waste heat.
Cryogenic/Special Medium Refrigeration
Employs low-temperature media-such as liquid nitrogen or liquid argon-for direct cooling, capable of achieving ultra-low temperatures below -45°C. It is primarily used for storing items with extreme low-temperature requirements, such as biological samples or specialized chemical raw materials.
Classification by Internal Cooling Method
Direct Cooling
The evaporator is mounted directly on the interior walls of the cold storage unit, absorbing heat directly from the space as the refrigerant evaporates. This method features a simple structure, low cost, and good moisture retention, making it suitable for small fresh-keeping storage facilities where humidity control is not critical.
Air Cooling
Fans distribute the cooling capacity generated by the evaporator evenly throughout the storage space. This method allows for automatic defrosting and ensures uniform internal temperatures, making it ideal for freezing facilities and pharmaceutical cold storage that require high precision in temperature control and a high degree of automation.
Indirect Cooling
A secondary refrigerant (such as brine) is cooled first and then circulated to cool the air within the storage space. While the cooling rate is slower, temperature fluctuations are minimal; this method is reserved for specialized cold storage applications requiring extremely constant temperatures.