A general optimized geometry of angled ribs for enhancing the thermo-hydraulic behavior of a solar air heater channel – A Taguchi approach

The thermo-hydraulic behavior of the air flow through a solar air heater is numerically simulated and then optimized by use of Taguchi method. An innovative general geometry is introduced for the rib that variation in its parameters can generate triangular, trapezoidal and rectangular geometries simultaneously. A L16 (44) orthogonal array is used to optimize the geometry factors accounts for the maximum thermal performance of the ribbed channel. Thermal performance concept includes maximization of heat transfer coefficient and minimization of friction factor. Maximization of thermal enhancement factor is taken as the criteria of optimization. At a constant flow Reynolds number of 10,000, rib relative pitch (P/H), rib relative height (e/H), rib relative tip width (a/H) and rib front projection (s) are employed as the design factors. Results show that rib pitch, rib height, rib tip width and rib front projection have the greatest influences on the thermo-hydraulic performance, respectively. A triangular rib geometry with rib height of 0.2H and P = 2H in which the rib front is normal to the flow direction (i.e. s = 0) is recognized as the optimum configuration.

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