Project ForgeThermodynamics
First Law of Thermodynamics
GATE 2019
Medium
Consider an ideal vapor compression refrigeration cycle. If the throttling process is replaced by an isentropic expansion process, keeping all the other processes unchanged, which statement is true for the modified cycle?
- Coefficient of performance is higher than that of the original cycle.
- BCoefficient of performance is lower than that of the original cycle.
- CCoefficient of performance is the same as that of the original cycle.
- DRefrigerating effect is lower than that of the original cycle.
Explanation
An isentropic expander recovers work (reducing net work input) AND lowers the enthalpy entering the evaporator more than an irreversible throttling valve would, increasing the refrigerating effect. Both effects raise COP = refrigerating effect / net work input above the throttling-cycle value.
Source: GATE ME 2019 Session 1 (Set 1) (2019)
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