A carnot engine uses Nitrogen as the working medium. The heat supplied is 53KJ and the adiabatic expansion ratio is 16:1. The receiver temperature is 295K. Detemine: 1. Thermal efficiency (percent) 2. Heat rejected (KJ) 3. Net Work (KJ)

An infinitely large sheet is subjected to a gross stress of 350 MPa. There is a central crack 5/π cm long and the material has a yield strength of 500 MPa. a. Calculate the stress-intensity factor at the tip of the crack. b. Calculate the plastic-zone size at the crack tip. c. Comment upon the validity of this plastic-zone correction factor for the above case.

A=164 b=1017 c=0 d=0 e=0.75 F=25

a) Heat leaks from the air in a kitchen through the walls of a refrigerator into the refrigerated cold space at a rate of 0.3 kW. The refrigerator operates in an ideal vapor compression refrigeration cycle between 1.2 bar and 9 bar. It uses refrigerant R-134a as the working fluid. Determine the coefficient of performance of the refrigerator.