Which process involves expanding the refrigerant to lower its pressure?

Which process involves expanding the refrigerant to lower its pressure?

• A. Expansion
• B. Condensation
• C. Evaporation
• D. Compression

Answer: (A)

The main idea being tested is that the refrigerant is lowered in pressure by expanding it. In a refrigeration cycle, the high-pressure liquid passes through an expansion device (like an expansion valve or capillary tube), which causes a rapid pressure drop with essentially no work. This throttling leads to a temperature decrease, producing the low-pressure, low-temperature mixture that then absorbs heat in the evaporator and vaporizes. This is different from condensation (vapor turning into liquid while releasing heat and typically increasing pressure downstream), evaporation (liquid turning into vapor by absorbing heat but not by expanding to lower pressure), and compression (raising pressure and temperature by doing work on the refrigerant).

The main idea being tested is that the refrigerant is lowered in pressure by expanding it. In a refrigeration cycle, the high-pressure liquid passes through an expansion device (like an expansion valve or capillary tube), which causes a rapid pressure drop with essentially no work. This throttling leads to a temperature decrease, producing the low-pressure, low-temperature mixture that then absorbs heat in the evaporator and vaporizes.

This is different from condensation (vapor turning into liquid while releasing heat and typically increasing pressure downstream), evaporation (liquid turning into vapor by absorbing heat but not by expanding to lower pressure), and compression (raising pressure and temperature by doing work on the refrigerant).