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In a Carnot engine working on ammonia, the high temperature is 60°C and as QH is received, the ammonia changes from saturated liquid to saturated vapor. The ammonia pressure at low temperature is 190 kPa. Find the entropy.

In a Carnot engine working on ammonia, the high temperature is 60°C and as QH is received, the ammonia changes from saturated liquid to saturated vapor. The ammonia pressure at low temperature is 190 kPa. Find the entropy. Correct Answer 4.6577 kJ/kg K

qH = ∫ Tds = T (s2 – s1) = T s(fg) = h2 – h1 = h(fg) = 997.0 kJ/kg TL = T3 = T4 = Tsat(P) = –20°C η(cycle) = 1 – (Tl/Th) = 1 – (253.2/333.2) = 0.24 s3 = s2 = sg(60°C) = 4.6577 kJ/kg K.

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