A heat recovery steam generator is a type of heat exchaner in which thermal energy is used to produce steam. The Dell Children’s Medical Center in Austin, TX uses an HRSG to produce wet steam from the hot exhaust gases of the Solar Turbine Mercury 50 gas turbine engine. The hot exhaust gases (model as air) enter the heat exchanger at 700 °F and at a mass flow rate of 38.7 lbm/s. Saturated liquid water enters the heat exchanger at 80 psia where it is converted to saturated vapor by receiving heat from the hot exhaust gases. The HRSG has a 2nd Law efficiency (effectiveness) of 80%. For this heat exchanger determine:a) the temperature of the exhaust gases (air) leaving the heat exchanger (°F).b) the mass flow rate of steam produced (lbm/s).

An ideal otto cycle with air as the working fluid has a compression ratio of 8. the minimum and maximum temperatures in the cycle are 300 k and 1340 k. use constant specific heats at room temperature to determine (a) the amount of heat transferred to the air during the heat- addition kj/kg, (b) the thermal efficiency, and (c) the thermal efficiency of a carnot cycle ope limits. process, in rating between the same temperature

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

Around steel bar, made from material with a yield stress of 750mpa, is loaded so that it has stresses co locations of maximum normal stress and maximum shear stress. use maximum shear stress and maximum distortion energy theories to calculate the safety factors for initial yielding failures.