1. As shown in Fig. P6.66, an insulated box is initially divided into halves by a frictionless, thermally conducting piston. On one side of the piston is 1.5 m3 of air at 400 K, 4 bar. On the other side is 1.5 m3 of air at 400 K, 2 bar. The piston is released and equilibrium is attained, with the piston experiencing no change of state. Employing the ideal gas model for the air, determine
state to a state where the temperature is 500 K, while volume remains constant.
(a) The temperature rise is brought about adiabatically by stirring the air with a paddle wheel. Determine the amount of entropy produced, in kJ/kg ? K.
(b) The temperature rise is brought about by heat transfer from a reservoir at temperature T. The temperature at the system boundary where heat transfer occurs is also T. Plot the amount of entropy produced, in kJ/kg ? K, versus Tfor
T$ 500 K. Compare with the result of (a) and discuss.