Boosting thermoelectric performance by employing novel fishtail shaped vortex generators in a heat exchanger: an experimental and numerical study

The present study investigates the influence of fishtail and envelope-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 = 2, 3, and 4 at θ = 60°, the percentage increment in the HTC at the exit control volume with the highest value of HTC of fishtail and envelope VG configurations are 395.74% and 263.45%, 445.98% and 254.74%, and 357.6% and 227.9%, respectively. The difference between the highest (M90) and lowest (F30) pressure drop values is 45%, 44%, and 37.78% for D/H ratios of 2, 3, and 4, respectively. The highest TEF is exhibited by fishtail VG configuration at D/H = 2 and θ = 60° with a value of 4.39. The power output of 1.57W, 1.54W, and 1.51W is achieved for the fishtail VG arrangement for D/H values of 2, 3, and 4 at θ = 60°. However, the highest TEG conversion efficiency of 3.29% is observed for D/H = 4 at an inclination angle of 60°. The study concludes that placing the vortex generators in a smooth channel enhances the system’s waste heat recovery potential. The distance-to-height ratio of 2 and angle of inclination of 60° for the fishtail VG is chosen as the best formation.