文档介绍：Thermal Energy Problem Set #4 – Fall 2002
Time spent on problems:
Problem 1:
Problem 2:
Problem 3:
Problem 4:
Problem 5:
Problem 6:
Thermal Energy Problem Set #4 – Fall 2002
Do all problems. Please use a separate sheet of paper for each problem.
1. A quantity of air undergoes a thermodynamic cycle consisting of three processes in
series.
o 3
Process 1-2: constant-volume heating from P1= MPa, T1= 15 C, V1= m
to P2= MPa
Process 2-3: constant-pressure cooling
Process 3-1: isothermal heating to the initial state
Employing the ideal gas model with cP=1 kJ/kgK, evaluate the change in entropy for
each process. Sketch the cycle on P-v coordinates.
2. A liquid system whose mass is m kg at temperature T was formed by adiabatically
bringing together two equal masses of the liquid; initially, one mass was at T1 and
the other at T2. Derive the entropy production for the system. Prove that the
entropy production for the system must be positive. Assume that the liquid has a
specific heat of cp.
3. A closed system consists of an ideal gas with constant specific heat ratio k.
a) The gas undergoes a process in which temperature increases from T1 to T2. Show
that the entropy change for the process is greater if the change in state occurs at
constant pr