A finned-tube, cross-flow heat exchanger is to use the exhaust of a gas turbine to heat pressurized water. Laboratory measurements are performed on a prototype version of the exchanger, which has a surface area of 10 m², to determine the overall heat transfer coefficient as a function of operating conditions.
Measurements made under particular conditions, for which m = 2 kg/s, Th = 325°C, and Te = 25°C, reveal a water outlet temperature of Te = 150°C. What is the overall heat transfer coefficient of the exchanger?
Taking for water C = 4203 J/kg°C and for air Cp = 1040 J/kgK.
A shell-and-tube exchanger (two shells, four tube passes) is used to heat 10000 kg/h of pressurized water from 35 to 120°C with 5000 kg/h water entering the exchanger at 300°C. If the overall heat transfer coefficient is 1500 W/m²K, determine the required heat exchanger area. Taking for cold water C = 4195 J/kgK and for hot water Cp = 4660 J/kgK.
A shell-and-tube heat exchanger is to heat 10000 kg/h of water from 16 to 84°C by hot engine oil flowing through the shell. The oil makes a single shell pass, entering at 160°C and leaving at 94°C, with an average heat transfer coefficient of 400 W/m²K. The water flows through 11 brass tubes of 22.9 mm inside diameter and 25.4 mm outside diameter, with each tube making four passes through the shell. Assuming fully developed flow for the water, determine the required tube length per pass. Take for brass: k = 137 W/m°C and for water k = 0.643 W/mK, Pr = 3.56, C = 4182 J/kg°C, p = 998.1 kg/m³, and m = 5.48 x 10â»â´ kg/m.