What is the basic function of coolant in chest freezers

Chest Freezers are refrigeration equipment designed for long-term preservation of food. Their main function is to significantly reduce the temperature inside the box through the circulation of coolant, thereby effectively extending the shelf life of food. Coolant plays a key role in the refrigeration process of the freezer. It not only affects the refrigeration efficiency of the equipment, but is also directly related to energy consumption, environmental impact and safety.

Definition and function of coolant
Coolant is a fluid used for heat exchange, usually in the form of gas or liquid. In the refrigeration cycle of the freezer, the coolant achieves refrigeration by absorbing and releasing heat. Its main functions include:
Heat absorption: The coolant absorbs the heat in the box in the evaporator, thereby reducing the internal temperature of the freezer.
Heat release: In the condenser, the coolant releases heat and discharges the heat to the external environment.
Circulation: The coolant circulates between the compressor, evaporator, condenser and expansion valve to form a closed refrigeration system to ensure the efficient refrigeration process.

Working principle of coolant
The refrigeration cycle of the freezer usually includes four main steps: evaporation, compression, condensation and expansion.
Evaporation process
In the evaporator, the coolant enters in liquid form and evaporates into gas by absorbing heat from the surrounding air. This process is the core of freezer refrigeration. The coolant absorbs a lot of heat in this process, significantly reducing the temperature inside the freezer, thereby effectively extending the shelf life of food.
Compression process
The evaporated gas coolant is transported to the compressor. At this stage, the pressure and temperature of the coolant are both increased, forming a high-temperature and high-pressure gas state, which is then transported to the condenser.
Condensation process
In the condenser, the coolant in a high-temperature and high-pressure state releases heat and turns into a liquid. In this process, the coolant transfers heat to the external environment through air or water. The efficiency of the condensation process directly affects the energy efficiency performance of the freezer, and is therefore crucial to optimizing the overall performance of the equipment.
Expansion process
After condensation, the coolant enters the expansion valve, where the pressure drops sharply. The coolant is once again converted into a low-temperature and low-pressure liquid, ready to re-enter the evaporator to complete a complete refrigeration cycle.
Types of coolants
There are many types of coolants, and different types of coolants have significant differences in performance, environmental impact, and safety. Common coolants include:
Freon (CFCs and HCFCs): These traditional coolants are gradually being phased out due to their destructive effects on the ozone layer and face strict regulation.
HFC (hydrofluorocarbons): As a substitute for Freon, HFCs perform well in terms of ozone depletion, but their global warming potential (GWP) is high and should be used with caution.
Natural coolants: such as ammonia (NH3), carbon dioxide (CO2) and hydrocarbons (such as propane). These coolants generally have lower environmental impact and higher energy efficiency, and are an important direction for the development of current cooling technology.