Engine oil (cp = 2048 j/kg. k) flows through a thin-walled copper tube at a rate of 0.3 kg/s. the engine oil enters at 80℃ and is cooled by water (cp = 4180 j/kg. k) entering the heat exchanger at 20℃. it is desired to limit the exit temperature of the engine oil to a maximum of 40℃. the convective heat transfer coefficients of the oil and water sides of the heat exchanger are 750 w/m2 . k and 350 w/m2 . k, respectively. if the water exits the heat exchanger at a temperature of 32℃, for a parallel flow heat exchanger, determine
(a) the mass flow rate of the water,
(b) the log mean temperature difference and
(c) the total area of the heat exchanger. (40 points)