What is the working principle of a compressor?
3 Answers
Compressor working principle is as follows: It sucks in low-temperature and low-pressure refrigerant gas from the suction pipe, compresses it through the operation of the motor driving the piston, and then discharges high-temperature and high-pressure refrigerant gas to the discharge pipe, providing power for the refrigeration cycle. This achieves the refrigeration cycle of compression→condensation (heat release)→expansion→evaporation (heat absorption). The compressor is regarded as the heart of the refrigeration system, and the most characteristic term for it is "vapor pump." The actual duty of the compressor is to increase pressure, raising the suction pressure state to the discharge pressure state. Compressors can be divided into positive displacement compressors and dynamic compressors based on their working principles. Positive displacement compressors are further categorized into reciprocating compressors and rotary compressors; dynamic compressors are divided into axial compressors, centrifugal compressors, and mixed-flow compressors. Main faults of compressors include: insufficient discharge capacity, abnormal temperature, abnormal pressure, unusual noises, overheating faults, bearing wear, corrosion, and casing cracks or ruptures.
The car's AC compressor is quite fascinating—it's powered by the engine belt. When I press the AC button, the compressor starts sucking in cool, low-pressure refrigerant gas and compresses it into a high-pressure, high-temperature state. Imagine squeezing a balloon—the more you squeeze, the hotter it gets. Then, this hot gas is pushed into the condenser at the front of the car, where the fan blows to dissipate heat, turning it into liquid. Next, the liquid refrigerant passes through an expansion valve as narrow as a needle's eye, suddenly decompressing into a low-temperature mist that sprays into the evaporator box, absorbing all the heat from the air blown through the dashboard, producing cold air. This cycle keeps the car's temperature stable, but the compressor consumes about 0.5 horsepower from the engine, so you'll need to press the accelerator harder when climbing hills with the AC on.
I like to call the compressor a 'heat mover'—it's essentially a miniature pressure factory in your car. Every time the AC kicks on, it clicks into action, compressing and heating up the refrigerant gas saturated with heat from the evaporator, akin to packing and pressurizing the chill from a freezer. Then, these high-temperature gases are pushed into the condenser at the front of the car, where they cool down and liquefy, much like a kettle releasing steam. The moment of sudden pressure drop is especially critical—when the liquid refrigerant sprays into the evaporator, its temperature plummets to around zero degrees, and the fan draws the sweltering air past it, absorbing the heat. This magical cycle consumes engine power roughly equivalent to three times the wattage of your headlights.
