A0.5-m3 rigid tank contains refrigerant-134a initially at 200 kpa and 40 percent quality. heat is transferred now to the refrigerant from a source at 35°c until the pressure rises to 400 kpa. determine

(a) the entropy change of the refrigerant

(b) the entropy change of the heat source

(c) the total entropy change for this process

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.