For certain applications, gas must pass through a long tube (usually coiled into a solenoid) to dissipate heat into the surrounding air, and thermally conductive metals such as copper are commonly used to transport vapor. To improve the efficiency of the condenser, heat sinks are often added to the pipes to accelerate heat dissipation. The heat sink is a flat plate made of good thermal conductivity metal. This type of condenser usually requires a fan to force air through the heat sink and remove the heat. The refrigeration principle of a general refrigeration machine is that the compressor compresses low-pressure steam into high-pressure steam, reducing the volume of the steam and increasing the pressure. 

The compressor sucks in the lower pressure working fluid vapor from the evaporator, increases its pressure, and sends it to the condenser, where it condenses into a higher pressure liquid. After being throttled by the throttle valve, it becomes a lower pressure liquid and is sent to the evaporator, where it absorbs heat and evaporates into lower pressure vapor, thus completing the refrigeration cycle.