Working Principle of Lab Companion Air-cooled Mechanical Compression Refrigeration

1.Compression

The low-temperature and low-pressure gaseous refrigerant flows out of the evaporator and is sucked in by the compressor. The compressor does work on this part of the gas (consuming electrical energy) and compresses it violently. When the refrigerant turns into high-temperature and high-pressure superheated vapor, the temperature of the vapor is much higher than the ambient temperature, creating conditions for heat release to the outside.

2. Condensation

The high-temperature and high-pressure refrigerant vapor enters the condenser (usually a finned tube heat exchanger composed of copper tubes and aluminum fins). The fan forces the ambient air to blow over the condenser fins. Subsequently, the refrigerant vapor releases heat to the flowing air in the condenser. Due to cooling, it gradually condenses from a gaseous state into a medium-temperature and high-pressure liquid. At this point, the heat is transferred from the refrigeration system to the outdoor environment.

3. Expansion

The medium-temperature and high-pressure liquid refrigerant flows through a narrow channel through the throttling device, which serves to throttle and reduce pressure, similar to blocking the opening of a water pipe with a finger. When the pressure of the refrigerant drops suddenly, the temperature also drops sharply, turning into a low-temperature and low-pressure gas-liquid two-phase mixture (mist).

4. Evaporation

The low-temperature and low-pressure gas-liquid mixture enters the evaporator, and another fan circulates the air inside the box through the cold evaporator fins. The refrigerant liquid absorbs the heat of the air flowing through the fins in the evaporator, rapidly evaporates and vaporizes, and reverts to a low-temperature and low-pressure gas. Due to the absorption of heat, the temperature of the air flowing through the evaporator drops significantly, thereby achieving the cooling of the test chamber.

Subsequently, this low-temperature and low-pressure gas is drawn into the compressor again, initiating the next cycle. In this way, the cycle repeats itself without end. The refrigeration system continuously "moves" the heat inside the box to the outside and dissipates the heat into the atmosphere through the fan.