Basic Refrigeration Exam with Questions and Answers

Basic Refrigeration Exam with Questions and Answers In a vapour compression refrigeration cycle, the process that primarily requires the largest input of mechanical work is which of the following? a) Expansion in the throttling valve b) Heat rejection in the condenser c) Compression of refrigerant vapour d) Evaporation in the evaporator Correct Answer: c) Compression of refrigerant vapour Rationale: In a vapour compression cycle, the compressor raises the pressure and temperature of the refrigerant vapour from low to high pressure. This process requires external mechanical work and is the main energy-consuming component of the system. Which thermodynamic property remains approximately constant during the throttling process in an ideal refrigeration cycle? a) Entropy b) Enthalpy c) Temperature d) Pressure Correct Answer: b) Enthalpy Rationale: Throttling (expansion through an expansion valve) is an isenthalpic process, meaning there is no heat transfer or work done, so enthalpy remains constant while pressure drops and partial vaporization may occur. The Coefficient of Performance (COP) of a refrigerator is defined as: a) Work input divided by heat removed from condenser b) Heat removed from cold space divided by work input c) Work input divided by heat absorbed in evaporator d) Heat rejected divided by work input