Consider a pistoncylinder arrangement containing 1 kg of R13

Consider a piston/cylinder arrangement containing 1 kg of R-134a with an initial pressure of 800 kPa and an initial temperature of 72 percentage C. Heat is added such that the piston rises while the temperature of the vapor remains constant and pressure drops to 150 kPa. Determine the work and heat transfer for this process assuming it is reversible.

Solution

>> As, P1 = Initial Temperature = 800 kPa

>> T = Temperature = 72 C = 345 K

>> P2 = Final Pressure = 150 kPa

>> m = mass of fluid = 1 Kg

>> R = Gas Constant = 8.314/102.03 = 0.0815

>> As, Work Transfer, W (in isothermal process) = mRT ln(P1/P2) = 1*0.0815*345*ln(800/150) = 47.06 kJ

=> Work Transfer = 47.06 kJ

As, Internal Energy Change = 0 ( because Teperature remains cinstant )

So, Heat Transfer = Work Transfer = 47.06 kJ