Experimental study and CFD simulation of wall effects on heat transfer of an extrudate multi-lobe particle

In this paper, heat transfer of a multi-lobe particle (tri-lobe, tetra-lobe and penta-lobe) affected by wall in cross and axial-flow was investigated numerically and experimentally. In numerical analysis, finite element method (FEM) was used for solving partial equations using FEMLAB version 2.3. The experimental work was performed for checking the accuracy of numerical results and computing the mass transfer coefficient. The heat and mass transfer analogy was applied for gaining the Nusselt number for each particle in axial and cross flow. The results showed that the cross flow heat transfer rate is more than axial flow. In addition, the size of particle for tri-lobe and tetra-lobe particles in axial flow and the effect of rotation-angle of tri-lobe particle on heat transfer in cross flow were investigated. The results showed that increasing the rotation angle can cause the Nusselt number to decrease. The influence of cylinder to particle diameter ratio (N) on heat transfer of particles in cross flow and axial flow was studied; the results depicted that when N is greater than 5 wall effects can be ignored. Moreover, Mirhashemi et al. correlation has been modified according to gaining CFD results for horizontal multi-lobe particles.