In a shell-and-tube heat exchanger 3kg/s of cold water is heated from 20 to 95C through the tubes by using engine oil supplied at 150C on the shellside. The oil provides an average convection coefficient of h0=800W/m2. K on the outside of the tubes. The shell and tube heat exchanger consists of one shell and 12 tubes. Each tube is thin walled, of diameter D=25mm, and makes 6 passes through the shell. The oil leaves the exchanger at 110C. a) what is the flow rate of the oil? b) what is the heat transfer coefficient of the water side? c) How long must the tubes be to accomplish the desired heating? Properties of engine oil at 130C:cp=2350J/kg.K