Atest is conducted to determine the overall heat transfer coefficient in a shell-and-tube oil-to-water heat exchanger that has 24 tubes of internal diameter 1.2 cm and length 2 m in a single shell. cold water (cp = 4180 j/kg·k) enters the tubes at 20°c at a rate of 3 kg/s and leaves at 55°c. oil (cp = 2150 j/kg·k) flows through the shell and is cooled from 120°c to 45°c. determine the overall heat transfer coefficient ui of this heat exchanger based on the inner surface area of the tubes. 8.31 kw/m2·k