CFD Analysis and Taguchi-Based Optimization of the Thermohydraulic Performance of a Solar Air Heater Duct Baffled on a Back Plate

Abstract

In this paper, a solar air collector duct equipped with baffles on a back plate was numerically investigated. The Reynolds number (Re) was varied from 5000 to 20,000, the angle baffle (a) from 30° to 120°, the baffle spacing ratio (Pr) from 2 to 8, and the baffle blockage ratio (Br) from 0.375 to 0.75 to examine their effects on the Nusselt number (Nu), the friction factor (f), and the thermohydraulic performance parameter (η). The 2D numerical simulation used the standard k-ε turbulence model with enhanced wall treatment. The Taguchi method was used to design the experiment, generating an orthogonal array consisting of four factors each at four levels. The optimization results from the Taguchi method and CFD analysis showed that the optimal geometry of a = 90°, Pr = 6, and Br = 0.375 achieved the maximum η. The influence of Br on all investigated parameters was considerable because as Br increased, a larger primary vortex region was formed downstream of the baffle. At Re = 5000 and the optimal geometry parameters, a maximum η of 1.01 was reached. A baffle angle between 60° and 90° achieved a high Nusselt number due to the impingement heat transfer.

Thermohydraulic Performance and Entropy Generation of a Triple-Pass Solar Air Heater with Three Inlets

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Heat Transfer Augmentation and Friction Factor Due to the Arrangement of Rectangular Turbulators in a Finned Air Channel of a Solar Air Heater

“…Singh et al [13] compared square wave ribs and multiple broken ribs, and showed that the multiple broken ribs had superior heat transfer and lower friction penalty in comparison to the square wave ribs. Thao et al [14] conducted a numerical investigation of an SAH coupled with inclined baffles and optimized the installation conditions of the baffles using the Taguchi method. Bhuvad et al [15] proposed a novel type of absorber plate roughened with apex-up discrete arc ribs, and compared the thermal performance achieved by the proposed ribs with those of the existing apex-down ribs.…”

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“…The baffle or partition inside the channels and cavities plays an important role in convective flow under various situations [26][27][28][29]. Mahapatra et al [30] discovered the opposite combined convective stream in a partitioned box with two partitions attached in the bottom and top walls.…”