Air enters the compressor of an air-standard brayton cycle with regeneration at 100 kpa and 300 k, with a mass flow rate of 6 kg/s. the compressor pressure ratio is 10 while the turbine inlet temperature is 1400 k. the turbine and compressor each have an isentropic efficiency of 80%, while the regenerator effectiveness is 80%. assuming constant properties evaluated at 300 k determine:

a) the thermal efficiency of the cycle

b) the back-work ratio

c) the net power produced, in kw

d) the rate of entropy generation in the regenerator, in kw/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