A car uses power of 25 hp for a one hour in a round trip. Thermal efficiency of 35% can be assumed? Find the change in entropy if we assume ambient at 20Â°C.

Mechanical Engineering : Engineering Thermodynamics - Quiz(MCQ)

254.1 kJ/K

354.1 kJ/K

654.1 kJ/K

554.1 kJ/K

Correct Answer : Option (C) : 654.1 kJ/K

Explanation : E = âŒ W dt = 25 hp × 0.7457 (kW/hp) × 3600 s = 67 113 kJ = η Q
Q = E / η = 67 113 / 0.35 = 191 751 kJ
âˆ†S = Q / T = 191 751 / 293.15 = 654.1 kJ/K.

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