6.42 Air contained in a rigid, insulated tank fitted with a paddle wheel, initially at 4 bar, 408C and a volume of 0.2 m3, is stirred until its temperature is 3538C. Assuming the ideal
gas model with k 5 1.4 for the air, determine
(a) the final pressure, in bar,
(b) the work, in kJ, and
(c) the amount of entropy produced, in kJ/K. Ignore kinetic and potential energy.
6.43 Air contained in a rigid, insulated tank fitted with a paddle wheel, initially at 300 K, 2 bar, and a volume of 2 m3, is stirred until its temperature is 500 K. Assuming the ideal gas model for the air, and ignoring kinetic and potential energy, determine
(a) the final pressure, in bar,
(b) the work, in kJ, and
(c) the amount of entropy produced, in kJ/K. Solve using
(a) data from Table A-22.
(b) constant cy read from Table A-20 at 400 K. Compare the results of parts (a) and (b).