A conterflow heat exchanger consists of a bundle of 20 mm diameter tubes contained in a shell. Oil flowing in the tubes is cooled by water flowing in the shell. The flow area within the tubes is 4.4...

A conterflow heat exchanger consists of a bundle of 20 mm diameter tubes contained in a shell. Oil flowing in the tubes is cooled by water flowing in the shell. The flow area within the tubes is 4.4
 10^–3
m². The flow of oil is 2.5 kg/s. It enters at 65C and leaves at 48C. Water enters the shell at the rate of 20 kg/s and at 15C. Calculate the area of the tube surface and the effectiveness of the exchanger. For the oil in the tubes, take Nu_d
= 0.023
 Pr^0.3, c_p
= 2.15 kJ/kg K,
 = 2.2
10^–5
Pa.s,
 = 880 kg/m³
, k = 190
 10^–6
kW/m K; for water, h = 1.2 kW/m²
K, c_p
= 4.19 kJ/kg K.