Section A
Q1.
(a) A wooden block of specific gravity 0.75 floats in water. If the size of the block is 1 mt × 0.5 mt × 0.4 mt, find its metacentric height.
(b) In a cold winter night with an outside ambient temperature of 2\circC, a wall of house steadily loses 30 kJ per minute. If the inner and outer surface temperatures of the wall are maintained at 25°C and 8°C, respectively, determine the rate of energy destruction within the wall in watts.
(c) What are the physical assumptions necessary for a lumped capacity unsteady state heat transfer analysis to be applied?
(d) The brake fuel conversion efficiency of an engine is 30%. The mechanical and combustion efficiencies are 80% and 94%, respectively. The heat losses to the oil and coolant are 60 kW. The chemical energy of the fuel entering the engine is 190 kW. What percentage of this energy becomes (a) brake power; (b) friction power; (c) heat losses; (d) exhaust chemical energy; (e) exhaust sensible energy?
(e) Briefly explain the working principle of a vortex tube refrigeration system.