Effects of spacing bars on the performance of spiral-wound heat exchanger and the fitting of empirical correlations

The effects of different arrangement styles of spacing bars on flow and heat transfer performance of spiral wound heat exchanger were numerically studied. The results show that, when the spacing bar are arranged in staggered style, the fluids in the low-velocity regions would flow into high-velocity regions because of the viscous force and the region near the spacing bar are easier to form eddies which enhance the interactions of the fluid in adjacent tube layer. The local details of temperature and flow field suggest that the staggered arrangement could strengthen both disturbance of the velocity field and heat transfer in the shell side. To evaluate the performance of the different arrangements of spacing bar, the TEFs (thermal performance factors) are calculated and the values indicate that the staggered arrangement of spacing bar has positive impact on the performance of SWHEs. However, the quantity of spacing bar has no significant influence on flow and heat transfer performance. The correlations of Nu number and friction factor f are fitted. The Nu number and friction obtained from correlations are in good agreement with numerical simulation data, the average errors of Nusselt number and friction factor are 4.66% and 7.49%, respectively.