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Applying the Entropy Balance: Closed SystemsAir as an
Chapter 6, Problem 49P(choose chapter or problem)
Air as an ideal gas contained within a piston–cylinder assembly is compressed between two specified states. In each of the following cases, can the process occur adiabatically? If yes, determine the work in appropriate units for an adiabatic process between these states. If no, determine the direction of the heat transfer.
(a) State 1: \(p_{1}=0.1 \mathrm{\ MPa}, \ T_{1}=27^{\circ} \mathrm{C}\). State 2: \(p_{2}=0.5 \mathrm{\ MPa}\), \(T_{2}=207^{\circ} \mathrm{C}\). Use Table A-22 data.
(b) State 1: \(p_{1}=3 \mathrm{\ atm}, \ T_{1}=80^{\circ} \mathrm{F}\) State 2: \(p_{2}=10 \mathrm{\ atm}\), \(T_{2}=240^{\circ} \mathrm{F}\). Assume \(c_{\mathrm{p}}=0.241 \mathrm{Btu} / \mathrm{\ lb}^{\circ} \mathrm{R}\).
Questions & Answers
QUESTION:
Air as an ideal gas contained within a piston–cylinder assembly is compressed between two specified states. In each of the following cases, can the process occur adiabatically? If yes, determine the work in appropriate units for an adiabatic process between these states. If no, determine the direction of the heat transfer.
(a) State 1: \(p_{1}=0.1 \mathrm{\ MPa}, \ T_{1}=27^{\circ} \mathrm{C}\). State 2: \(p_{2}=0.5 \mathrm{\ MPa}\), \(T_{2}=207^{\circ} \mathrm{C}\). Use Table A-22 data.
(b) State 1: \(p_{1}=3 \mathrm{\ atm}, \ T_{1}=80^{\circ} \mathrm{F}\) State 2: \(p_{2}=10 \mathrm{\ atm}\), \(T_{2}=240^{\circ} \mathrm{F}\). Assume \(c_{\mathrm{p}}=0.241 \mathrm{Btu} / \mathrm{\ lb}^{\circ} \mathrm{R}\).
ANSWER:Step 1 of 3
We have to find the workaround for adiabatic process
Given
MPa,
°C=300 K.
MPa,
C=480 K.
To determine if the process can occur adiabatically, begin with the closed system entropy balance:
In an adiabatic process, Since
cannot be negative.