EXPERIMENTAL AND NUMERICAL STUDIES OF SHELL-AND-TUBE HEAT EXCHANGERS WITH HELICAL BAFFLES

摘要

In the present paper, flow and heat transfer characteristics of shell-and-tube heat exchanger with continuous helical baffles (CH-STHX) is experimentally studied. Correlations for heat transfer and pressure drop, which are estimated by Nusselt number and friction factor, are fitted by experiment data for thermal design. Computational Fluid Dynamic (CFD) method is also used to compare the heat transfer and flow performance of STHX with continuous helical baffles (CH-STHX), STHX with combined helical baffles (CMH-STHX) and STHX with discontinuous helical baffles (DCH-STHX). The numerical results show that, for the same Reynolds number, the Nusselt numbers Nu_o of the CMH-STHX and CH-STHX is about 37.6%, 78.2% higher than that of the DCH-STHX; the friction factor f_o of the CH-STHX is about 14.8% and 150.2% higher than that of CMH-STHX and DCH-STHX. If the velocity ratios R_(CMH) and R_(DCH,CH) are bigger than 1.55 and 4.0 in the Nusselt number range from 40 to 70, the CMH-STHX and the DCH-STHX may have higher Nusselt numbers than the CH-STHX for the same mass flow rate in the shell side.