Saturated water vapor has a flow rate of 1.5 kg/s and a pressureof 0.51 bar. The vapor is to be completely condensed to saturatedliquid in the shell of a shell-and-tube heatexchanger. In this case, the water vapor enters and the water exitsat the same temperature, which represents a case with infinitelyhigh m_dot * Cp for this condensing steam application. On the tubeside, city water is used as the cold fluid. The city water entersthe thin-walled tubes at 17°C and leaves at 57°C. Assume an overallheat transfer coefficient of 2000 W/m2-K.
After extended operation, fouling causes the overall heattransfer coefficient to decrease to 1000 W/m2-K, and to completelycondense the vapor, there must be a reduction in the vapor flowrate. For the same inlet temperature of the city water and flowrate of the city water, calculate the following:
- Fouled NTU = ?
- Fouled epsilon = ? (No need for derivation. Use the providedequation for Cr = 0)
- Fouled qmax = ? Is there a reason for fouled qmax to bedifferent from the clean qmax?
- Fouled q = ?
- What is the vapor flow rate required for complete condensationin the fouled exchanger?
