Microchannel heat sinks provide the solution to the ever-increasing heat flux generated from micro-electric components. In this study, performance optimization of a microchannel heat sink with delta winglet vortex generators was carried out based on the data obtained from numerical CFD simulations. A total of 192 design points were generated by altering the fluid velocity in terms of Reynolds number (Re), winglet width (W d), length (L d), and the angle of attachment (β) of the winglet. The Artificial Neural Network (ANN) model coupled with Non-dominated Sorting Genetic Algorithm NSGA-II was used simultaneously to minimize the friction factor and increase the Nusselt number. The ANN model predicted the output values within the error limit of 10%. The Pareto optimal front generated by the algorithm contains the input parameters in the range 982 < Re < 988, 177 μm < L d < 233 μm, 10 μm < W d < 25 μm, 57 • < β < 64 •. Decision-making methods TOPSIS, LINMAP, and Shannon entropy were employed to calculate the optimal solution from the data set and the obtained points showcased 70%, 120% and 158% surge in Nusselt number while an increase of friction factor by 35%, 109%, and 140% respectively is reported. The Performance Evaluation Criteria (PEC) values obtained from the best solutions were 1.52, 1.72, and 1.92, respectively. Furthermore, the accuracy of the optimal solutions was verified numerically. The flow and thermal field of the microchannel are also analyzed, and results showed that the angle of attachment and width of the winglet played a crucial role in the overall performance.

The increasing fuel prices have led researchers to work on the efficiency and development of heat-transferring devices. One such device is the hot water radiator, which is familiar in the domestic arena. The study aims to increase the efficiency and cooling performance of hot water 3D radiators by modifying the design of their fins and adding perforations for better fluid mixing. CFD simulations were carried out on the radiators with modified fin geometries (Wavy, Spike-rib, Cut-sections, Straight) and with two different intensities of perforation (19 and 38 perforations) for each case at varying inlet flowrates of the radiator. The numerical model in this study was validated with experimental work. The hydrothermal performance of each radiator was measured in terms of fin surface temperature, entropy generation, heat transfer rate, and thermal enhancement factor. The temperature distributions and fluid flow streamlines have also been shown. The results show that modifying the fin geometries augments the overall heat transfer rate by up to 131 % while perforating the fins boosts the rate to 134 %. Moreover, the radiation heat transfer is seen to have surpassed the convection heat transfer by 60–160 % for the modified radiator cases. Finally, the most efficient radiator is found based on the thermal enhancement factor, which is the spike-fin arrangement.

Vortex generators are passive methods of heat transfer enhancement in any thermal system. However, more research is needed to compare the effects of vortex generators having unique shapes on the flow distribution for high heat transmission. Also, a research gap exists in analyzing how different angular orientations of the vortex generator (VG) affect thermohydraulic performance. Therefore, this CFD study aims to propose a total of five novel vortex generator shapes applying modification on a rectangular VG shape, analyzing and comparing the heat transfer and pressure drop properties in a rectangular channel for the Reynolds number varying in the range of Re=4000–11,000. VG-1 (vortex generator-1) with three triangles on its top side, VG-2 with concave shape arc, VG-3 combined with a rectangle and a triangle, VG-4 consists of a rectangle and two triangles at two corners, while VG-5 consists of a rectangle with a triangular inside cut. Among the five designs, VG-1 gives the most optimal hydrothermal performance, incrementing Nusselt number and friction factor of about 38.2 % and 80.38 %, respectively. Combining these two dimensionless parameters, we get the maximum thermal performance factor, TPF, for VG-1, whereas VG-2 performs the least in terms of TPF. Moreover, compared with conventional rectangular VG, VG-1 performed the best with a 1.63 % increase in TPF. Considering the effect of different angular orientations, VG-1 was further studied by applying five vertical inclination angles and four horizontal rotation angle configurations to investigate the impact of inclination and rotational angles. Minimizing the pressure drop penalty, the 30˚ inclination design had the best hydrothermal performance overall, with the highest TPF range of 1.19–1.41, whereas 120˚ variants had the lowest TPF, at 1.09–1.31. Also, for the configuration of the horizontal rotations, 30˚ angle gives the best result, having a slight edge over 150˚case with 1.17–1.41 TPF. Finally, the best cases from vertical inclination and horizontal rotation are combined in a new hybrid configuration, which yielded the maximum TPF of 1.22–1.45, indicating that this configuration is the most effective among all the cases.

A compact heat exchanger known as the helical tube heat exchanger (HTHE) is frequently used in various thermodynamic operations, including condensation and evaporation processes in refrigerators, thermal energy storage systems, and many other heating systems. This study proposes the effect of different curvature ratios and the heat exchanger's different geometrical profiles. For the same length of the helical tube, the pitch values and the winding numbers are different for various curvature ratios. HHX-1, HHX-2, and HHX-3 are the considered designs with different curvature ratios, each having three (3) different types of geometric profiles, namely Case A, Case B, and Case C, for investigating the convective heat transfer rate and pressure drop. The current numerical scheme has been validated with existing literature work to showcase the accuracy. The simulations are conducted for HTHE, conditioned for constant wall temperature. A range of 16000-29000 Reynolds numbers has been employed for a water-based MWCNT-water nanofluid at a volume concentration of 0.4%. ANSYS FLUENT was used for the simulation purpose and post-processing of the results. For the result analysis, outlet temperatures, Nusselt numbers, and pressure drops are observed to determine the increase in heat transmission, pumping power requirements and compare the proposed designs. Among all designs, HHX-3 with Case A profile showed the best augmentation of heat transmission where the range of Nu is 118-164. For the visualization of fluid flow and thermal dissipation characteristics, the 2D contour of temperature and velocity streamlines are extracted from the post-processing part, which shows their changes.