Hot water (0.01 m3
/min) enters the tube side of a counter current shell
and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3
/min)
of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log
mean temperature difference in °C is approximately
(A) 32
(B) 37
(C) 45
(D) 50