Numerical Analysis of Heat and Fluid Flow in Shell and Tube Heat Exchangers Equipped with Continues Helical Baffles with Emphasis on the Geometrical Ratios of Shell and Pipe Diameters and Baffle's Pitch

Shell and tube heat exchangers equipped with segmental baffles are the most widely used kind of heat exchangers in industrial applications. Nowadays, substitution of the heat exchangers equipped with helical baffles is a new methodology to improve of the heat exchangers efficiencies. In this paper, heat and fluid flow fields through the heat exchangers equipped with continuous helical baffles are analyzed numerically using the computational fluid dynamics, CFD. Also the effects of two major geometrical ratios: the shell to pipe diameters, D/d, and the baffle pitch to shell diameter, B/D, on the efficiency of the heat exchangers are studied. Numerical methodology of solution and governing equations is validated by repetition numerical analyze of a heat exchanger that have experimental data for comparison. Consistency between the numerical and experimental are occurred. The results show that in both cases of baffles, for D/d near to 11.5, the variations of temperature difference between output and input of the shell with respect to D/d, changes from decreasing manner to increasing manner, while the variations of the pressure drop changes inversely, i.e. from increasing to decreasing manner. Similar results to the above also occurred near to the ratio of the baffle pitch to shell diameter, B/D of about 2. Comparison between the segmental and continuous helical baffles shows lower pressure drop and upper temperature differences for heat exchangers equipped with the later baffles.