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Analyzing Thermodynamic CyclesA gas within a
Chapter 2, Problem 74P(choose chapter or problem)
A gas within a piston-cylinder assembly undergoes a thermodynamic cycle consisting of three processes in series, beginning at state 1 where \(p_1=1\) bar, \(V_1=1.5 \mathrm{~m}^3\), as follows:
Process 1-2: Compression with pV = constant, \(W_{12}=-104 \mathrm{~kJ}\), \(U_1=512 \mathrm{~kJ}, U_2=690 \mathrm{~kJ}\).
Process 2-3: \(W_{23}=0, Q_{23}=-150 \mathrm{~kJ}\).
Process 3-1: \(W_{31}=+50 \mathrm{~kJ}\).
There are no changes in kinetic or potential energy. (a) Determine \(Q_{12}, Q_{31}\), and \(U_3\), each in kJ. (b) Can this cycle be a power cycle? Explain.
Questions & Answers
QUESTION:
A gas within a piston-cylinder assembly undergoes a thermodynamic cycle consisting of three processes in series, beginning at state 1 where \(p_1=1\) bar, \(V_1=1.5 \mathrm{~m}^3\), as follows:
Process 1-2: Compression with pV = constant, \(W_{12}=-104 \mathrm{~kJ}\), \(U_1=512 \mathrm{~kJ}, U_2=690 \mathrm{~kJ}\).
Process 2-3: \(W_{23}=0, Q_{23}=-150 \mathrm{~kJ}\).
Process 3-1: \(W_{31}=+50 \mathrm{~kJ}\).
There are no changes in kinetic or potential energy. (a) Determine \(Q_{12}, Q_{31}\), and \(U_3\), each in kJ. (b) Can this cycle be a power cycle? Explain.
ANSWER:Part (a)
Step 1 of 5:
A piston-cylinder arrangement has undergone series of three thermodynamic processes. The kinetic and potential energies are constant. The volume of the system undergoes a change and pV remains constant. We are going to find the heat energy and the internal energy of the system specified.
Pressure at the beginning p1 = 1 bar
Volume of the gas at the beginning V1 = 1.5 m3
Process 1-2:
pV = Constant
The Work done W12 = -104 kJ
The internal energy U1 = 512 kJ
The internal energy U2 = 690 kJ
Process 2-3:
The Work done W23 = 0
The heat energy Q23 = -150 kJ
Process 3-1:
The work done W31 = 50 kJ