Numerical investigation on gas flow heat transfer and pressure drop in the shell side of spiral-wound heat exchangers

As a critical facility, spiral-wound heat exchanger (SWHE) has been widely used in many industrial applications. A computational fluid dynamics (CFD) model was employed with the smallest periodic element and periodic boundary conditions to examine the characteristics of the shell side of SWHE. Numerical simulation results show that the heat transfer coefficients around the tube initially increase and subsequently decrease with radial angle because of the influence of backflow and turbulent separation. The mean absolute deviation between simulated heat transfer coefficients and measured values for methane, ethane, nitrogen and a mixture (methane/ethane) is within 5% when Reynolds number is over 30000. For the pressure drop, the simulated values are smaller than the measured values, and the mean absolute deviation is within 9%. Numerical simulation results also indicate that the pressure drop and heat transfer coefficients on the shell side of SWHE decrease as the winding angle of the tubes increases. Considering the effect of winding angle on pressure drops and heat transfer coefficients, the modified correlations of Nusselt number Nu = 0.308Re0.64Pr0.36(1 + sinθ)-1.38 and friction factor f = 0.435Re-0.133(sinθ)-0.36, are proposed. Comparing with the experimental data, the maximum deviations for heat transfer coefficients and pressure drops are less than 5% and 11% respectively.