Process Equipment and Plant Design
In a shell and tube heat exchanger for a given heat transfer surface area, smaller diameter tubes are favoured as compared to larger diameter ones ; because the smaller diameter tubes

Are less prone to fouling
Are easier to clean
None of these
Can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less

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Process Equipment and Plant Design
Ponchon Savarit method is based on the use of enthalpy concentration diagram, which contains the bubble point curve (saturated liquid curve), dew point curve (saturated vapour curve) and equilibrium tie lines. As compared to McCabe-Thiele's method, this method

Accounts for the enthalpy changes in the process
Facilitates direct calculation of heat load on reboiler & condenser from, the diagram used in this method
Is more accurate in finding the number of equilibrium stages
All of these

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