Question

wam 2 physlet workshe. 13 X Islam 6 1 2 a and b 2nd low * BNG 220 sp20... 1. Air in a piston cylinder device at 300kPa undergoes isobaric compression during which its temperature decreases from 450 K to 375 K. Calculate the amount of heat transfer (in kJ/kg) and work transfer (in kJ/kg) associated with this compression. You may treat air as an ideal gas.

Answer 1

Note: To find the quantities in unit of kJ/kg ,there is need of mass of gas given in question.

* Solution:- moc Pressure, p= 300 kPa = 300 x 10% pa for isobaric compression, $ = constant initial temperature , Ti = 450K final temperature, Tf = 375 K .: work done, w = 6 Mav' = f ( Vf - Vi ) = nRCT - Ti) given in question) consider, n=1 mole (not W= 8.314 (375-450) =-623.55 J → W = -0.62 KJ ! ** Cv = r and Cp = (1 + £) R where, f= degrees of freedom = 3 (for air) → Cv = ZR, CP = SER . Heat transfer, dQ = nCp dT = ER *(Tf-Ti) → 08 = 5 x8-314x (-75) = - 1558-88 J → 49 = -1.56 kJ] 100 = 1.56 kJl(acc. to sign convention) n=1