What best defines a compressor?

A compressor is fundamentally a device that plays a critical role in refrigeration and air conditioning systems by taking a low-pressure vapor and compressing it into a high-pressure vapor. This process is essential for the refrigeration cycle, as it enables the refrigerant to circulate through the system, absorbing heat from the environment and releasing it in a different location.

When the refrigerant vapor is compressed, its temperature rises significantly due to the increase in pressure, allowing it to release heat when it passes through the condenser. Understanding this function is key to recognizing how cooling systems maintain desired temperatures. In contrast to the other options presented, which describe different components or processes related to refrigeration but do not accurately represent the primary function of a compressor, this definition clearly aligns with the essential operational mechanism of a compressor in HVAC systems.