A shell-and-tube heat exchanger with single shell and 50 tube passes is used to cool the engine oil of a
large diesel. Lake water enters the shell-side at 3 kg s−1 and 280 K. The shell-side convection coefficient
is approximately 400 W m−2 K−1. The oil at 420 K enters 50 copper tube passes. Each pass is 10 m
long and has inner and outer diameters of 20 and 24 mm, respectively. The mass flow rate of oil is
5 kg s−1. Fouling is negligible on both sides of the heat exchanger. The calculations should be performed
using properties at assumed average temperatures of water, oil, and copper.
Questions:
a) Calculate the overall heat transfer coefficient for the oil side (40%).
Hint: When calculating the heat transfer coefficient for oil (hot fluid), first check the flow regime
by calculating the Reynolds number (laminar or turbulent). Also, check whether the flow is
developing (in entrance region) or fully developed. Then use the appropriate Nusselt number
correlation.
b) Calculate the oil outlet temperature
Hint: Use the e-NTU method. Start determining UA.