Consider the flow of engine oil (c p = 2048 J/kg·K) through a thin-walled copper tube at

Question:

Consider the flow of engine oil (c_p= 2048 J/kg·K) through a thin-walled copper tube at a rate of 0.3 kg/s. The engine oil that enters the copper tube at an inlet temperature of 80°C is to be cooled by cold water (c_p= 4180 J/kg·K) flowing at a temperature of 20°C. It is desired to have exit temperature of the engine oil not greater than 40°C. The individual convective heat transfer coefficients on oil and water sides are 750 W/m²·K and 350 W/m²·K, respectively. If a thermocouple probe installed on the downstream side of the cooling water measures a temperature of 32°C, for a double pipe parallel flow heat exchanger determine

(a) Mass flow rate of the cooling water

(b) Log mean temperature difference,

Hot oll 80°C Cold water 20°C