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Analyzing Internally Reversible ProcessesNitrogen (N2)
Chapter 6, Problem 26P(choose chapter or problem)
Nitrogen \(\left(\mathrm{N}_{2}\right)\) initially occupying \(0.1 \mathrm{\ m}^{3}\) at 6 bar, \(247^{\circ} \mathrm{C}\) undergoes an internally reversible expansion during which \(p V^{1.20}=\text { constant }\) constant to a final state where the temperature is \(37^{\circ} \mathrm{C}\). Assuming the ideal gas model, determine
(a) the pressure at the final state, in bar.
(b) the work and heat transfer, each in kJ.
(c) the entropy change, in kJ/K.
Questions & Answers
QUESTION:
Nitrogen \(\left(\mathrm{N}_{2}\right)\) initially occupying \(0.1 \mathrm{\ m}^{3}\) at 6 bar, \(247^{\circ} \mathrm{C}\) undergoes an internally reversible expansion during which \(p V^{1.20}=\text { constant }\) constant to a final state where the temperature is \(37^{\circ} \mathrm{C}\). Assuming the ideal gas model, determine
(a) the pressure at the final state, in bar.
(b) the work and heat transfer, each in kJ.
(c) the entropy change, in kJ/K.
ANSWER:Part (a)
Step 1 of 6:
Nitrogen gas occupies a certain volume undergoes internally reversible expansion. The initial and final pressures are given. The pV relationship is also given. We are going to find the final pressure.
The initial volume V1 = 0.1 m3
The initial pressure p1 = 6 bar = 10 x 105 N/m2
The initial temperature T1 = 247°C = 520 K
The final temperature T2 = 37°C = 37 K
The gas constant R = 8314/28.01 Nm/kg.K = 8.314/28.01 kJ/kg.K
Molar mass of nitrogen M = 28.01 kg/k.mol