Shell-and-tube heat exchangers design details

Shell-and-Tube Heat Exchangers Design Details... 

The shell and tube heat exchange design using Aspen Plus is done as that in Example 4.4. The process flow sheet and stream table properties are shown in Figure 4.37. The Exchanger details are shown in Figure 4.38. 

Figure 1.7 Simple detail of shell-and-tube heat exchanger. The water box may be designed for as many as eight passes, and a variety of configurations of shell-side baffles may be used to improve heat transfer, (a) Several water box arrangements for tube-side cooling, (b) Assembly of simple two-pass exchanger with U-tubes. [Fig. 38.2, The Nalco Water Handbook, 1st ed. (1979), reprinted with permission from McGraw-Hill, Inc.)...

Typical film coefficients can be used to build rough overall heat transfer coefficients. This should suffice in most cases to establish that the design is within ballpark accuracy. Later, for final design, certain critical services will be checked in detail. Typical film resistances for shell and tube heat exchangers and overall heat transfer coefficients for air cooled heat exchangers are shown in Chapter 2, Heat Exchangers. 

The various components which make up a shell and tube heat exchanger are shown in Figures 9.63 and 9.64 and these are now considered. Many different mechanical arrangements are used and it is convenient to use a basis tor classification. The standard published by the Tubular Exchanger Manufacturer s Association (TEMA 97 ) is outlined here. It should be added that noting that Saunders 98 has presented a detailed discussion of design codes and problems in fabrication. 

The validated numerical model can be used to predict optimum geometries in process equipment, such as cross-flow filters and shell and tube heat exchangers which reduce the eddy losses due to pipe contractions. Details of such a design procedure are given by Nassehi et. al [11]. 

Figure 18.2 Details of a Shell-and-Tube Heat Exchanger (From D. R. Woods, Process Design and...

The complex flow pattern on the shell-side, and the great number of variables involved, make it difficult to predict the shell-side coefficient and pressure drop with complete assurance. In methods used for the design of exchangers prior to about 1960 no attempt was made to account for the leakage and bypass streams. Correlations were based on the total stream flow, and empirical methods were used to account for the performance of real exchangers compared with that for cross flow over ideal tube banks. Typical of these bulk-flow methods are those of Kern (1950) and Donohue (1955). Reliable predictions can only be achieved by comprehensive analysis of the contribution to heat transfer and pressure drop made by the individual streams shown in Figure 12.26. Tinker (1951, 1958) published the first detailed stream-analysis method for predicting shell-side heat-transfer coefficients and pressure drop, and the methods subsequently developed... 

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