Heat exchanger shell-side pressure drop

Whitley, D. L., Galculating Heat Exchanger Shell-Side Pressure Drop, Chem. Eng. Prog, V. 57, No. 9, p. 59 (1961). 

ESDU Engineering Sciences Data Unit Report 83038 Baffled shell and tube heat exchangers flow distribution, pressure drop and heat transfer on the shell side. (ESDU International, London 1983)... 

Fredheim, A.O. Thermal design of coil-wound LNG heat exchangers, shell-side heat transfer and pressure drop , Dr.ing. thesis, NTH, 1994... 

The design calculations highlighted the shortcomings of the Kern method of exchanger design. The Kern method fails to account for shell-side inefficiencies such as bypassing, leakage, crossflow losses, and window losses. This leads to a marked overestimate of the shell-side heat-transfer coefficient and shell-side pressure drop. The Bell method is recommended to correct these deficiencies. 

For flow of a gas or liquid across the tubes on the shell side of a shell-and-tube heat exchanger, a preliminary estimate of the shell-side pressure drop can be made by the method of Grimison (1937). The pressure drop is given by a modified Fanning equation ... 

Heat exchanger pressure drop is mainly a function of velocity, that is, tube velocity for tube side pressure drop and bundle velocity for shell side pressure drop. 

It is to be noted that the ratio of the friction factor / to the heat transfer factor J for compact ribbon-packed heat exchangers is approximately equal to the ratio of / to j reported in the present work. F rom this it may be concluded that more compact heat exchangers can be designed with helically finned and coiled tubing, which also represents a Collins type of heat exchanger, without any sacrifice in shell-side pressure drop. 

Flows are usually turbulent on both the tube and shell sides of coiled tube heat exchangers. To calculate pressure drops for single-phase tube side flows, it is simplest to use the normal Fanning friction factor correlation for... 

There are many text books that describe the fundamental heat transfer relationships, but few discuss the complicated shell side characteristics. On the shell side of a shell and tube heat exchanger, the fluid flows across the outside of the tubes in complex patterns. Baffles are utilized to direct the fluid through the tube bundle and are designed and strategically placed to optimize heat transfer and minimize pressure drop. 

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... 

The procedure for calculating the shell-side heat-transfer coefficient and pressure drop for a single shell pass exchanger is given below ... 

Taborek J (1992) Calculation of Shell-side Heat Transfer Coefficient and Pressure Drop in GF, Hewitt Handbook of Heat Exchanger Design, Hemisphere. 

When considering the steam side of steam heated reboilers, it is best to think about the reboiler as a steam condenser. The steam, at least for a conventional horizontal reboiler, is usually on the tube side of the exchanger, as shown in Fig. 8.1. The steam is on the tube side, because the shell side was selected for the process fluid. If the reboiler is a thermosyphon, or natural-circulation reboiler, then low-process-side pressure drop is important. For a horizontal reboiler, it is easiest to obtain a low pressure drop for the fluid being vaporized by placing it on the shell side. 

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