We have explored the result of the activation energy, thermal conductivity, and variable viscosity, A vertical wavy surface is passed by heat sources during convective heat transfer. Coupled equations controlling the flow, the nonlinear, mass, and heat transferring an electrically conducting viscous fluid via a vertically wavy surface have been solved with the Runge-Kutta-Shooting approach. ( f′, f ) the velocities, (φ)concentration and (θ)temperature, Sherwood and Nusselt number were discussed for several variations of Ds, Dc, E1, δ, Rd, β, θr, A1, B1, a, ξ. It has been seen that axial velocity increases with rising values of Ds, Dc, E1, Nr and reduces with thermal radiation (Rd), and thermal conductivity (β). Nusselt number (Nu) reduces with temperature dispersion (Ds), variable viscosity(θr), thermal conductivity (β) and enhances with solutal dispersion (Dc), radiation (Rd). Space/temperature dependent heat sources (A1, B1).

The study aims to quantify the effect of Dufour number, on flow patterns and heat transfer rates in the exponentially accelerated vertical plate with MHD flow and chemical reaction. The unsteadiness of the flow suggests that time-dependent changes in velocity, temperature, and other relevant parameters are considered. MHD further complicates analysis with the electromagnetic interactions between the fluid and the field. The fluid, be characterized as a gray, absorbing/emitting radiation medium, indicating that it absorbs and emits thermal radiation but does not exhibit scattering behavior. Set of partial differential equations are then resolve using FEM. Graphical results are then discussed. Profiles vary with different, Dufour number, radiation, or temperature-dependent heat source/sink parameter. By varying the values of these governing parameters, on the skin-friction coefficient, Nusselt number, and Sherwood number are also analyzed.

This study examines turbulent convective heat transfer performance (CHTP) and entropy production rate (EPR) of distilled water flowing in outwardly corrugated converging pipes (CCPs) of various diameter ratios (DR). The SST k - ω turbulence models were used to simulate the flow of H 2O inside the pipe. The effects of Reynolds number ( 5 . 0 × 10 3 ≤ Re  ≤ 5 . 0 × 10 4 ), and DR ( 1 ≤ DR  ≤ 2 ) on average Nusselt number ( Nu ), Poiseuille number (fRe) thermal performance evaluation criterion (PEC), EPR, and thermal effectiveness number ( I ) Nu were investigated parametrically. The findings revealed a significant improvement in Nu in the modified pipe compared with the straight pipe. This improvement is attributed to flow acceleration and increases in the mixing rate of hot fluid near the wall with cold fluid at the core fluid zone. Also, Nu , fRe , and EPR increase with increasing Re and DR. However, the opposite is the case for PEC and   I . Finally, the values of PEC, and I revealed that the modified pipe is advantageous compared with a straight pipe at ( 5 × 10 3 ≤ Re ≤ 1 . 0 × 10 4 ) .

The study aims to find the optimal fin length distribution for improved heat transfer during melting and solidification in a tubular PCM heat exchanger designed for heat storage. Three types of horizontal PCM tabular heat exchangers, all with five longitudinal fins, were studied numerically. While maintaining a constant heat transfer area, each model depicts a unique fin length distribution design. The first model, which serves as the reference design, has a homogeneous fin length distribution and each fin is 30 mm long. The second model has shorter upper and side fins and longer lower fins (20 mm for the upper fin, 25 mm for the side fins, and 40 mm for the lower fins). The third model has long lower fins but shorter than that of second model, short side fins and no change in upper fin length with reference design (30 mm for upper fin, 25 mm for side fins and 35 mm for lower fins). The findings indicate that the second model exhibits the best heat transfer performance for the melting process, while the first model is most effective for solidification. Interestingly, the third design emerges as the optimum choice for both melting and solidification processes.

While a variety of solar concentrators have been studied for decades, the study of the spherical glass concentrator has never been reported, to the best of our knowledge. For that, this paper examines the optical characteristics of the novel solar spherical glass concentrator and identifies its performance and features. In addition, the thermal and exergetic performance of the concentrator are studied with three cavity receiver designs under various operating temperatures and different mass flow rates. More specifically, the examined receiver shapes: spiral, conical, and cylindrical. All the cavities are analyzed in order to determine the best design which maximizes the thermal efficiency of the solar collector. According to the results, the spherical collector can concentrate the heat flux up to 25 times the incident flux value. Also, the study is defined the best receiver dimensions that achieve optimum optical performance. Then, the optical analysis is conducted with an optical simulation in COMSOL Ray Optics to validate this work’s findings. Moreover, the best design is found to be the one with a spiral shape, while the conical is the next choice. The cylindrical is the third design in the performance sequence.