Chapter 11, Problem 11.44P

Saturated water vapor leaves a steam turbine at a flowrate of 1.5 kg/s and a pressure of 0.51 bar. The vapor isto be completely condensed to saturated liquid in ashell-and-tube heat exchanger that uses city water as the cold fluid. The water enters the thin-walled tubesat 17°C and is to leave al 57°C. Assuming an overall heat transfer coefficient of $2000{\text{ W/m}}^2\cdot \text{K}$ , determinethe required heat exchanger surface area and the water flow rate. After extended operation, fouling causesthe overall heat transfer coefficient to decrease to $1000{\text{ W/m}}^2\cdot \text{K}$ . and to completely condense the vapor, there must be an attendant reduction in the vapor flow rate. For the same water inlet temperature and flowrate, what is the new vapor flow rate required for complete condensation?