Using Energy Concepts and the Ideal Gas Model As shown in Fig. 3.111, a piston–cy...

Using Energy Concepts and the Ideal Gas Model

As shown in Fig. 3.111, a piston–cylinder assembly fitted with a paddle wheel contains air, initially at p₁ = 30 lbf/in.², T₁ = 540°F, and V₁ = 4 ft³. The air undergoes a process to a final state where p₂ = 20 lbf/in.², V₂ = 4.5 ft³. During the process, the paddle wheel transfers energy to the air by work in the amount of 1 Btu, and there is energy transfer to the air by heat in the amount of 12 Btu. Assuming ideal gas behavior, and neglecting kinetic and potential energy effects, determine for the air (a) the temperature at state 2, in °R, and (b) the energy transfer by work from the air to the piston, in Btu.