Question

thermodynamics

In a polytropic process with the expansion exponent of n=1.3, 2kg ethane gas at 500 kPa and 100°C brought to 20°C. Calculate the total entropy generation for the process.

Answer 1

solution is In Initial = 500 kpe polytropic process, expension exponent an=13. mars of ethere gas=m=2 =219. pressure api Initial temperature =T final temperature = T2 = 20°C = 293.2°% Let the final pressure = P2 for polytropic procen, proj constant. FIDUC = 373.2k ham) P2= (3) Pz = 500) 333-2 T2 Boro) 293.2 e la SL r'. Pa E 175.809 lpe work done P212 PIVI R[T2 ~Ti] i-ng For ethone gas, R=0.2765 kJ kopos Cv = 1.49 KT lgok cpe 1.766 KI lpok ha 6.965) (243-2 - 3732) 1-13) lah = 73.733 IT/14 Heat transfer 1올 Cv (Tz -T.] + "al (1-49)(293.2 – 373.2] + 73.733 q= 45.467 165/84 Entropy change = ($2~5s cp in (17/1/2) =R ln (A - = 69-7663 in (992) – (0.2945) In ( 1 con - (seasi) = -0.1371 KI lp.k

Entropy generation Q Tamb Sagen = {m (52-5,)- =(16) = 0.371) - Sagen 1) (-0.371) - (2)(-45.467] 293.2) (2 Sagen a to.0359 KT K +0. 0359 KT Entropy generation for the process le