Question

This Question is on seventh addition,"FUNDAMENTAL OF ENGINEERING THERMODYNAMICS"
QNS # 3.113 page 154

3.113 Carbon dioxide (CO2) contained in a piston–cylinder
arrangement, initially at 6 bar and 400 K, undergoes an
expansion to a final temperature of 298 K, during which the
pressure–volume relationship is pV1.2 5 constant. Assuming the
ideal gas model for the CO2, determine the final pressure, in
bar, and the work and heat transfer, each in kJ/kg.

Answer 1

Calculate the final pressure by using following relati on (n-I n 12 298 K (12) 400K x(6 bar) = 1.03 bar Calculate the work done as follows: (8.314kJ/kmol K)/(44.01 kg/kmol)(298 K -400 K) - 96.34 kJ/ kg Calculate the average specific heat at constant volume as follows: )0.750 kJ/ kg K 0.657 kJ/kg K Cy0KC300K) (0.750 kJ/ kg K)+(0.657 kJ/kg K) - 0.7035 kJ/ kg-K Calculate the change in internal energy - (0.7035 kJ/ kg K) (300 K- 400 K) -70.35 kJ/ kg Energy balance for the given system, we have --70.35 kJ/ kg +96.34 kJ/ kg = 25.99 kJ/kg