Aplane wall, 7.5 cm thick, generates heat internally at a rate of 105 w/m3. one side of the wall is insulated, and the other side is exposed to an environment at 90oc. (i. e. the fluid is at a temperature of 90oc.) the convection heat transfer coefficient between the wall and the environment is 500 w/(m2 k). if the thermal conductivity of the wall is 12 w/(m k), calculate the temperature in the center of the wall.

Arefrigerator uses r-134a as the working fluid and operates on the ideal vapor-compression refrigeration cycle except for the compression process. the refrigerant enters the evaporator at 120 kpa with a quality of 34 percent and leaves the compressor at 70°c. if the compressor consumes 450 w of power, determine (a) the mass flow rate of the refrigerant, (b) the condenser pressure, and (c) the cop of the refrigerator. (0.00644 kg/s, 800 kpa, 2.03)