Question

The fluid in a heat exchanger in a process plant needs to be warmed up prior to having process startup. The shell side of the heat exchanger contains the process fluid (water) while the tube side is supplied with steam at 150°C to facilitate the heating. Assume the exterior is well insulated such that heat losses are negligible.

a) Derive the ODE and analytically solve for the function that describes the temperature of the fluid in the heat exchanger with respect to time.

b) If the overall heat transfer coefficient is 250 W/m2K, the area of the heat exchanger is 650 m2, the volume of water is 12.5 m3, the density and cp of the water are 990 kg/m3 and 4200 J/kg K respectively, how long would it take to have the water at 140°C?

Answer 1