How many pressure levels does every mechanical refrigeration system have?

• A. One
• B. Three
• C. Two
• D. Four

Answer: (C)

Two pressure levels are involved in every mechanical refrigeration system. The compressor creates a high-pressure side where the refrigerant releases heat in the condenser, while the expansion device drops the pressure to a low level so the refrigerant can absorb heat in the evaporator. This setup lets the refrigerant change phase and move heat from the space being cooled to the surroundings. If there were only one pressure level, the cycle couldn’t drive heat transfer or promote the necessary phase changes. More than two levels would indicate a more complex, multi-stage design rather than the standard basic cycle. So, two pressure levels is the standard for a basic mechanical refrigeration system.