Air contained in a rigid, insulated tank fitted with a paddle wheel, initially at 4 bar, 40oC and a volume of 0.2 m3, is stirred until its temperature is 353oC. Assuming the ideal gas model with γ=1.4 for the air. Ignore kinetic and potential energy. Determine: (a) (10%) the final pressure, in bar; (b) (15%) the work, in kJ; (c) (15%) the amount of entropy produced, in kJ/K.

Acommercial grade cubical freezer, 4 m on a side, has a composite wall consisting of an exterior sheet of 5.0-mm thick plain carbon steel (kst= 60.5 w/m k), an intermediate layer of 100-mm thick polyurethane insulation (kins 0.02 w/m k), and an inner sheet of 5.0- mm thick aluminium alloy (kal polyurethane insulation and both metallic sheets are each characterized by a thermal contact resistance of r 2.5 x 104 m2 k/w. (a) what is the steady-state cooling load that must be maintained by the refrigerator under conditions for which the outer and inner surface temperatures are 25°c and -5°c, respectively? (b) for power saving purpose, which wall material should be increased/reduced in. thickness in order to reduce 50% of the cooling load found in part (a)? redesign the thickness of the proposed material. 177 w/m-k). adhesive interfaces between the q=575.93 w