Thermoelectric performance enhancement by employing fishtail and delta-shaped vortex generators in a heat exchanger: An experimental and numerical study

The present study investigates the influence of fishtail and delta-shaped vortex generators on the performance of a heat exchanger integrated with a thermoelectric generator (TEG). The effects of the distance-to-height ratio (D/H) and the inclination angle (θ) of the vortex generator configurations on key thermohydraulic parameters—temperature distribution, pressure drop, heat transfer coefficient (HTC), Nusselt number, friction factor, and thermal enhancement factor (TEF)—along with their impact on TEG performance metrics, namely power output and conversion efficiency, are systematically analyzed. The heat exchanger and thermoelectric generator system is modeled using a one-dimensional steady-state heat transfer approach, assuming incompressible hot air flow with constant thermophysical properties. For D/H values of 2, 3, and 4 at an inclination angle of 60°, the maximum percentage increase in HTC within the exit control volume is observed as 535.7 % and 333.0 % for fishtail and delta-shaped VGs at D/H = 2, followed by 448.6 % and 293.6 % at D/H = 3, and 359.6 % and 289.9 % at D/H = 4, respectively. The pressure drop exhibits a significant variation, with the disparity between the highest (D90) and lowest (F30) values recorded as 97.2 %, 96.0 %, and 86.13 % for D/H ratios of 2, 3, and 4, respectively. The highest thermal enhancement factor (TEF) is attained for the fishtail VG configuration at D/H = 2 and θ = 60°, with a value of 4.97. Correspondingly, the power output for this configuration is recorded as 1.62 W, 1.60 W, and 1.54 W for D/H values of 2, 3, and 4, respectively. However, the peak TEG conversion efficiency of 3.29 % is achieved at D/H = 4 and θ = 60°. This study’s findings underscore vortex generators’ efficacy in augmenting waste heat recovery potential.