Question

1. It is desired that the heating duty of a shell-and-tube heat exchanger be scaled up as much as possible. Under nominal condition a process stream (a liquid) is heated

from 120°C to 160°C without any phase change by condensing steam on the shell side at 250°C. The process side has a bypass which remains closed under nominal condition. The maximum increase in the process side pressure drop through the heat exchanger can be only 44%. Some portion of the process stream can be bypassed, if needed, but it is desired that the temperature of the mixed stream after the bypass and the exchanger outlet streams are mixed remains at 160 C. The maximum increase in the steam flowrate is 50%, but the pressure of the condensing steam can be changed to change the condensation temperature. Show your work. Assume that both the tube-side and shell-side heat transfer coefficients de not change due to scale up. Assume that the change in the density and specific heat of the process stream due to temperature is negligible.change in the condensation temperature/pressure. Also assume that the pressure drop through the heat exchanger is proportional to the square of the mass flow through the heat exchanger,Assume that the latent heat for steam condensation does not change due to \text { i.e. } \quad-\Delta P_{f r} \propto \dot{m}^{2} a. What is the maximum possible scaleup? b. What would be the required steam condensation temperature for the maximum scaleup?

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