Quick Manual Design of Shell and Tube Heat Exchangers

The purpose of this thesis is to provide a general procedure to, quickly estimate the approximate size of a shell and tube heat exchanger, including multiple shells in series and/or parallel, and dimensions required for entering rating calculations. This procedure is an expansion and refinement of the procedure given in Section 3.1.4 ofthe Heat Exchanger Design Handbook (Bell, 1983). The procedure is useful for a preliminary plant layout, cost estimation, and as a check on the output of computer-based design procedures. Chapter 1 discusses the general usefulness of an approximate design method for shell and tube heat exchangers and describes both the essential and desirable features of such a method. A brief description of the components of a shell and tube heat exchanger, the various types of shell and bundle constructions, and the general selection criteria are also presented. Chapter 2 deals with the basic structure ofthe design method. It includes a brief description of the concepts of conduction, convection and radiation. Also presented are procedures for the estimation ofQ (total heat duty), MTD (mean temperature difference), individual film heat transfer coefficients (a's) and overall heat transfer coefficient (Uo), and the number of shells required to perform the specified duty. The existing version of the design method, with its limitations, is also described. In Chapter 3, the relationship of the heat transfer area, A, to the basic shell dimensions (shell inside diameter and effective tube length) is developed. A. generalization of the outside area/shell dimensions relationship for the reference case to other tube sizes and layouts, bundle types, number of tube side passes and finned tube dimensions is also developed. Chapter 4 presents a procedure for the estimation of tube counts. An approximate method for estimating the baffle cut and baffle spacing as a function of the shell inside diameter is also presented. Vibration limitations are also described. The Summary and Conclusions are given in Chapter 5 and Recommendations in Chapter 6. The use of the approximate design method is illustrated in the form of an example problem in the appendix. Also given are various tables for the estimation of film and overall coefficients for various cases, fouling factors, dimensions of bare and finned tubes and detailed tables and plots for the estimation of the correction factors