Question

Mumiework Problem HW2.4 If you don't remember this term, look it up. It's important for this problem Nitrogen expands adiabatically in a piston-cylinder assembly from an initial state where pa = 7 bar, v4 = 0.2552 m3/kg and T1 = 600 K, to a final state where p2 = 1.5 bar. The process is polytropic with n = 1.4. The change in specific internal energy, in kJ/kg for nitrogen can be approximated as Au = uz-u, = (0.81 kJ/kg-K)(T2-T) (T's in K) Assuming kinetic and potential energy effects can be neglected, determine the following: a) Assumptions, b) Heat transfer per unit mass, in kJ/kg and its direction. c) Work per unit mass, in kJ/kg and its direction. d) Final temperature, in K. b) O c) 159 d) 403.7 6

Answer 1

Assumptions -

1.Closed system.

2.Quasistatic or Reversible.

3.Ideal gas

Adin bahe o.25T2 6o0 K Tt 5) Heat Thoms e per ut man a) zero the hon- as Proden a Adiab ht Work Y for Ada fpnocers 11 m 4 TX S X 2 O 252 O.7 669 2 lort pe uit oss Y- Too xo-1552)-(D X 0-749 o4 W=IS9 o13 /K

(T-T) AL st law A u AUw 1 thermody namins Hhs - Au Aw 0.81T,- T) 0.FI(600- T) IS.013 O13 T 600- 196.2 402.8 K 2