experimental and cfd study of the tube configuration effect on the shell-side thermal performance in a shell and helically coiled tube heat exchanger

Despite numerous studies of shell and helically coiled tube heat exchangers, a fewinvestigations on the heat transfer and flow characteristic consider the geometricaleffects like coil pitch. moreover, this scarcity is highlighted for the shell side of thistype of heat exchangers. this study reports experimental and computational fluiddynamics (cfd) investigations on heat transfer and flow characteristics of a shelland helically coiled tube heat exchanger. the experiments were carried out using ahelically coiled tube, which was placed in a cylindrical shell. hot and cold waterwere used as the process fluids on the tube and shell side, respectively. the cfdmodeling technique was employed to describe the experimental results, fluid flowpattern, and temperature profiles as well as dead zones in the heat exchanger.quantitative predicted results of cfd modeling show a good agreement with theexperimental data for temperature. the effect of the coil pitch on heat transfer ratewas numerically studied and it was found that the heat transfer coefficient intensifieswith an increase in coil pitch. the average turbulent kinetic energy (k) for the oldcoil tube and twice coil pitch heat exchanger was computed as 2.9×10-3 and 3.3×10-3m2/s2, respectively. this indicates an increase of about 14% in flow turbulent kineticenergy. nusselt numbers were compared with those estimated using publishedcorrelation and a mean relative error (mre) of 14.5% was found between theexperimental and predicted data. however, a good agreement was obtained in lowershell reynolds numbers (lower than re=200).