In an oil cooler, 0.06 kg s of hot oil enters a thin metal pipe of diameter 25 mm. an equal mass flow rate of cooling water flows through the annular space between the pipe and a larger concentric pipe. the oil and water move in opposite direc- tions. the oil enters at 420 k and is to be cooled to 320 k. if the water enters at 290 k, what length of the pipe will be required? take heat transfer coefficients of 1.6 kw m k- on the oil side and 3.6 kw m-2 k-1 on the water side and 2.0 kj kg1 k-1 for the heat capacity of the oil and 4.18 kj kg k for the heat capacity of water.