An automobile radiator may be viewed as a cross-flow heat exchanger with both fluids unmixed. Water enters the radiator at a flow rate of 0.05 kg/s and a temperature of 400 K, and leaves the radiator at 330 K. The water is cooled by air that enters at a rate of 0.75 kg/s with a temperature of 300 K. (a) If the overall heat transfer coefficient is 200 W/m2K, what is the required heat transfer surface area

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.