On the solar air heater thermal enhancement and flow topology using differently shaped ribs combined with delta-winglet vortex generators

A numerical investigation has been conducted to study the convective heat transfer enhancement and friction loss behaviors for turbulent flow by using arrays of differently shaped ribs combined with deltawinglet vortex generators (DWVGs) pair on the absorber plate of a solar air heater. Four transverse vortex generators arrays, i.e., 90 degrees continuous ribs, 90 degrees truncated ribs, 60 degrees V-shaped continuous ribs, and 60? Vshaped truncated ribs, are studied to investigate the mixing effect with the DWVGs pair. The aspect ratio (AR = L-v/H-v) of the DWVGs is 2:1 while the geometrical condition of the ribs is height of 0.003 m and pitch of 0.028 m. The Reynolds number ranges from 4000 to 20,000. Results of temperature, Nusselt number, vortical structure, topological portrait, turbulent kinetic energy (TKE), friction factor and thermal performance evaluation are included. The results show that the adoption of DWVGs and the shape type of the ribs have great impact on the heat transfer and flow structure in the solar air heater. It is found that the DWVGs combined with the 60 degrees V-shaped continuous ribs contributes the best heat transfer performance, and the heat transfer is enhanced by 39.4% compared with the only DWVGs case. (C) 2021 Published by Elsevier Ltd.

Automated summary

A numerical study was conducted to investigate convective heat transfer enhancement and friction loss behaviors in turbulent flow using differently shaped ribs and deltawinglet vortex generators in a solar air heater. The results showed that combining deltawinglet vortex generators with 60 degrees V-shaped continuous ribs resulted in the best heat transfer performance, with a 39.4% enhancement compared to using only the vortex generators.