Entropy Change - GATE '97 ME
A system undergoes a state change from 1 to 2. According to the second law of thermodynamics for the process to be feasible, the entropy change, S2-S1 of the system
A. is positive or zero
B. is negative or zero
C. is zero
D. can be positive, negative, or zero
Answer: Entropy change of the system can be positive, negative or zero.
Entropy change of the system can be positive in case of work producing devices (ex. Turbines) and entropy change can be negative in case of work consuming devices(ex Compressors).
But for combined entropy change for system and surroundings must always increase for irreversible process or equal to zero for reversible process.
The entropy change of the system and surroundings can not be negative.
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