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Functional relations are derived to determine the reduction in the heat duty of a multipass heat exchanger due to tube-side fluid bypass. A simplified structural model of the channel cover is constructed to determine the interpass leakage due to cover deflection under pressurized (operating) conditions. A numerical example shows that design rules based on stress limits are adequate to keep interpass leakage within tolerable limits.

The mathematical problem of minimizing gross solids entrainment in an n-stage evaporator is formulated and solved using the method of Lagrange multipliers. The solution procedure enables direct comparison of the decontamination efficiencies of multistage evaporators as the number of stages (n) is varied. A numerical example is utilized to illustrate the method of solution. Equivalent expressions for batch distillation are also derived.

The basic criteria are derived in determining whether the heat transfer relationship for a given heat exchanger geometry is invariant to the interchanging of shell-side and tube-side fluids. It is shown that the total heat duty, LMTD correction factor, and other indices of exchanger performance remain unchanged for a stream-symmetric exchanger when the two flow streams are switched, provided the overall heat transfer coefficient is not changed.

A simplified design procedure is presented to determine tubesheet thickness in U-tube, floating-head, and fixed-tubesheet shell-and-tube exchangers. The procedure is based on classical plate-and-shell theory and permits a design code-oriented manual solution procedure. The configuration analyzed includes an unperforated rim, three different tubesheet head-shell-joint configurations, and arbitrary material properties for each component. Thermal loading due to differential radial expansion and the effect of local pressures acting on the head and shell walls are included.

A method for computing the thickness of a tubesheet extension (rim) used as a flange is proposed. The method treats both fixed and floating-head stationary tubesheets and U-tube tubesheets. Numerical examples illustrate the calculation method.