The optimum design of shell-and-tube heat exchangers is an interesting subject in engineering, because it is interrelated with constructional, operational and economic issues. In the present work a detailed geometric consideration of tube layouts is conducted and a method for precise calculation of tube counts is given. Furthermore, some issues concerning the design of tube-sheets and baffles are examined. The calculations were performed through a mathematical approach by introducing a

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... istic parameter, the value of which depends on the number of tubes and therefore can be given in tables. A simple working equation was also derived for the calculation of shell diameter of a heat exchanger for a given number of tubes, tube diameter and tube pitch. The results, compared with those obtained by approximate relationships or tables available in the literature, showed that the method of the present study is complete, rapid and with the best accuracy.