Optimization of baffle spacingon heat transfer, pressure drop and estimated price in a shell-and-tube heat exchanger

摘要

In this paper for a given heat duty, study of the effects of baffle spacing on three parameters mentioned above is considered in a STHX with single segmental baffles and staggered tubes layout in Iran, Arvand petrochemical. A program in EES (Engineering Equations Solver) software is used for this purpose to solve governing equations; moreover, Aspen B-JAC and HTFS+softwares are used for considering estimated total price. At first the simulated results obtained from this program is compared to the experimental data for two cases of baffle spacing. The effects of baffle spacing are considered from 4 to 24 inches over overall heat transfer coefficient (OHTC) to pressure drop ratio (U/Δp ratio). The results show that U/Δp ratio is low when baffle spacing is minimum (4 inches) because pressure drop is high; however, heat transfer coefficient is very significant. And in this case estimated total price increases 7 percent. Then with the increase of baffle spacing, pressure drop rapidly decreases and OHTC also decreases, but the decrease of OHTC is lower than pressure drop, so (U/Δp) ratio increases. After increasing baffles more than 12 inches, variation in pressure drop is gradual and approximately constant and OHTC decreases; Consequently, U/Δp ratio decreases again. If baffle spacing reaches to 24 inches, STHX will have minimum pressure drop, but OHTC decreases, so required heat transfer surface increases and U/?p ratio decreases. After baffle spacing more than 12 inches, variation of both estimated price and shell side pressure drop is negligible. So optimum baffle spacing is suggested between 8 to 12 inches (43 to 63 percent of inside shell diameter) for a sufficient heat duty, low cost and low pressure drop. © IDOSI Publications, 2012.