An attempt is made to improve the overall performances of channel heat exchangers. The techniques of baffles and nanofluids are combined to enhance the dynamic and thermal behaviors within the channel exchanger. Baffles under various attack angles are used as vortex generators. In addition, oil/multiwalled carbon nanotubes (MWCNT) is used as a working fluid. Both inclinations in the upstream and downstream directions were considered, referenced as Case A (UIB) and Case B (BIB), respectively. While the channel equipped with vertical baffles is referenced as Case C. The proposed models with combined techniques allowed a considerable enhancement in the overall efficiency. The comparison between the three cases revealed that the most significant value of thermal enhancement factor (TEF) of 5.634 was reached with vertical baffles (Case C) at the highest value of Reynolds number. When using inclined baffles, the 75° upstream attack angle (Case A) allowed the highest TEF of 4.814, compared with Case B.

The present paper is a numerical investigation on the performance of perforated baffles in a plate-fin heat exchanger. Two types of perforations are studied, namely the circular and elliptical shapes. Values of heat transfer coefficient, pressure drop, and thermal performance factor are determined for both cases and compared with those for a smooth channel. Also, the flow fields and heat transfer characteristics are determined for different fluids and various Reynolds numbers. The working fluids are complex, non-Newtonian and have an inelastic shear thinning behavior. The obtained results showed a good enhancement in the thermal performance factor by the suggested design in baffles. In the case of low viscous fluids, the elliptical perforated baffle performs better (by about 63.4%) than the circular one for all values of Reynolds number. But for highly viscous fluids, the elliptical perforation shows higher thermal performance than the circular hole by about 25% for low Reynolds numbers and 27% for high Reynolds numbers. The overall thermal performance factors are about 1.55 and 1.74 for the circular and elliptical perforations, respectively.

The study aimed to enhance the heat transport by improving the hydrodynamic structure of the system by changing and restructuring the duct's internal geometry. Modern fins, of the shape ‘V’, have been proposed with different dimensions, and they are periodically arranged over the duct surfaces. The most important steps of this research are the change in the V-fin attack-angle (40°–80°), length (H _b/2, 3H _b/4, H _b, 5H _b/4 and 3H _b/2), and separation length (D _s/2, 3D _s/4, D _s and 5D _s/4), as well as the flow rate (6 × 10³–3 × 10⁴). The study yielded an optimum case for a 40-degree attack-angle, with a factor of thermal enhancement of 2.163 for the highest value of Reynolds number. On the other hand, improving the length of the V-fins or decreasing in the space between them, increases the flow strength by enlarging the recycling cells, which reflects on the hydrodynamic behavior, and changes the heat transfer. The presence of this new model of fins also highlights a hydrothermal improvement ranging between 1.196 and 23.779 percent compared to the previously indicated models, reflecting the effectiveness of the new system of solar heat exchangers with air V-finned ducts.