The Design of Tube Plates in Heat Exchangers

Up to the present time designers of heat exchangers have used an empirical method for determining the tube plate thickness. This is based on the formula for the maximum stress in a thin circular plate under uniform loading. It takes no account of the support given to the tube plate by the tubes, and does not attempt to differentiate the weakening effects of different tube hole spacings.

In this paper, these two factors are considered. A definite algebraic expression is introduced to cover the weakening effect of the holes, and the support given by the tubes is accounted for by treating the tube plate as a thin circular plate resting on an elastic foundation. This gives rise to fairly complicated mathematics, which are fully set out, but there is no need to refer to the mathematics in the design of a particular tube plate, as the analysis leads to fairly simple design formulae and the procedure for using them is indicated in simple terms. Four familiar types of heat exchanger are considered, and design formulae have been developed for the maximum stress in both the tube plate and the tubes.

An experimental test was carried out on the tube plate of an existing heat exchanger, and the results are shown to be in reasonable agreement with the proposed theory. To illustrate the method three examples are worked out, and by comparison of the results with those obtained by the existing method it is shown that a reduction in the thickness of the tube plate can be obtained.