On the optimum conditions for baffle installation in the backward facing step flow for maximization of the baffle performance

摘要

Various studies have shown that a baffle installation can enhance heat transfer in the backward facing step flows. This increases the pressure drop in the channel, as well. Therefore, naturally a question comes up here. In which location and orientation a given baffle should be installed to have the highest possible performance? In this study, the main focus is to find the best installation location X _(b)and Y _(b)) and orientation ( α ) for a given baffle to maximize its thermal performance. To this end, a steady incompressible laminar flow was considered in a channel with an expansion ratio R _(E)= 2. The bottom wall of the channel is partially heated with a constant heat flux. For numerical modeling, the Navier—Stokes equations were solved using the finite element method. Two new concepts entitled the maximum temperature constraint and the performance evaluation parameter (PEP) were defined to characterize the problem. Grid independence study was performed, and the numerical simulation was validated successfully with the published results. As the main result, a small zone close to the step was identified for the baffle installation which gives higher values of the PEP and constrained PEP (CPEP). It was shown that under the present circumstances, the case ( X _(b), Y _(b), α ) = (0.3, 0.9, −15°) gives the highest heat transfer enhancement (75 ) and the case ( X _(b), Y _(b), α ) = (0.3, 0.9, 30°) is the most optimum case from the thermal performance point of view with C _(PEP)= 1.257.