The main purpose of this study is to investigate numerically the thermal performance of a parabolic trough solar collector’s absorber tube that contains a novel kind of inserts with the objective to improve the heat transfer between the heat transfer fluid and the absorber tube. In the first part of this paper, the diameter and the length of the cylindrical inserts are investigated based on Finite Volume Method and Monte Carlo Ray Tracing method for Reynolds number ranges from 2.36∙10^4 to 7.09∙10^4. In the second part, the eccentricity of the cylindrical inserts is investigated under the same operating conditions. The Therminol ®VP1 is the HTF that used in this investigation intermediate fluid. The numerical simulation indicates that the perturbators enhance the thermal behavior of receiver and reduces the absorber tube’s temperature difference.

This study's primary objective is to demonstrate how diffusion-thermo and thermal diffusion influence of peristaltic flow processes with slip boundaries when joule heating happens from the interior. Several operational factors and their impacts on the system were analysed, along with the corresponding graphs. As slip parameters rise, the axial pressure gradient fluid flow tends to drop. The pressure rate is demonstrated to drop in the backward and peristaltic pumping regions as the quantity of the second order slide parameter rises, whereas it rises in the co-pump zone. As slip parameters rise, fluid temperature and concentration tend to drop. Changes in the thermal diffusion and thermo diffusion factors cause changes in the fluid's temperature and concentration. The Nusselts number can be increased by increasing the Prandtl number, the thermo-diffusion constraint, the dufour number, and the Schmidt number. However, this will result in fewer Sherwood number.

Slag entrapment from metal-slag interface during continuous casting operation has been a major area of concern for steelmakers globally. The presence of inactive regions in the upper region of the mold poses another challenge. Proper flow behavior of the molten metal coming out of the nozzle in the mold is required to overcome these challenges. Nozzle design greatly affects the flow pattern of the molten steel inside the mold. The present investigation is an attempt to study the flow and solidification behavior in a slab caster mold with the use of a novel designed hexa-furcated nozzle (HFN) using numerical investigation results. The casting speed and submerged entry nozzle (SEN) depth are varied to study the effect of these parameters on minimizing the inactive zones in the mold and the steel/slag interface fluctuations. The results show that the interface fluctuation increases at higher casting speed and lower SEN depth. The RTD analysis is also performed for different cases to investigate the flow behavior. The validation of the fluid flow and RTD curve inside the computational domain is carried out with the use of physical modeling.

The main focus of the current study is to examine the impact of melting heat transfer and chemical reactions on MHD micropolar fluid flow over a sheet that is exponentially stretching and immersed in a porous medium in which the source of heat is not uniform. Also taken into consideration are slip phenomena and thermal radiation. The governing PDEs are converted to a system of ODEs via similarity transformation and the necessary boundary conditions. These nonlinear ODEs are resolved with the help of shooting techniques and an RK-4 iterative strategy. Also, solved this problem using the Bvp4c approach for validating the results of the RK-4 method. Both outcomes are consistent with previously published data. With the help of tables and graphs, we examine the influence of multiple physical parameters on velocity, thermal profile, microrotation, concentration profiles, Nusselt number, Sherwood number, coefficient of skin friction, and Wall couple stress. We see that the temperature distribution and velocity profiles decrease when the melting parameter increases. The temperature profile boost when the heat source parameter is increased.

The impacts of vertical throughflow, rotation, cross-diffusion, and vertical heterogeneous permeability on the double-diffusive convection in a finite rotating vertical porous cylinder have been studied. The fluid in the cylinder is warmed and salted from beneath, and its top and lower walls are taken to be isothermal, isosolutal and permeable. In the model formulation, the Brinkman model was adopted, coupled with the Boussinesq approximation. The normal mode technique is used to perform linear stability analysis and single term Galerkin technique is employed to solve the eigenvalue problem. Further, the influence of vertical heterogeneity, vertical throughflow, thermal and solute Rayleigh, Taylor, and the Soret and Dufour numbers on the fluid system instability has been investigated. We found, among other results, that vertical heterogeneity may either stabilize or destabilize the fluid system. The Dufour number delays both the stationary and oscillatory convection onsets. The positive Soret number is found to have a stabilizing effect on the stationary convection case, with a destabilizing effect on the oscillatory convection case.

The current study focuses on the thermal distribution in the boundary layer of a wedge with a variable surface temperature. The governing equations of MHD flow for variable wall temperature conditions can be converted to ODE by using similarity solutions, and the Hartmann number (Ha) from 1 to 3 can be solved via the colocation method. This method’s results are compared to those of the numerical method, and it is then evaluated and validated. As the angle or Ha increases, the width of the hydrodynamic boundary layer decreases, and the slope of the boundary layer increases, increasing the coefficient of friction on the surface. The results are obtained for variable wall temperature (n), Prandtl number (Pr) and Eckert number (Ec), where they are 0.5≤n≤1.5, 0.5≤Pr≤5, and 0.001≤Ec≤0.002, and at a certain angle. It is observed that when Ha, Pr, and n increase, the thermal boundary layer grows faster than before; thus, thickness decreases and the Nusselt number (Nu) rises; however, as the Ec adds, the Nu decreases on the wall.

This work investigates the effect of Joule heating and viscous dissipation due to electric double layer (EDL) and electroosmotic effect on steady fully developed electromagnetohydrodynamic flow in a porous microchannel. Dimensionless formulations of the Poisson-Boltzmann, momentum, and energy equations are derived for the electric potential, velocity profile and temperature distribution in the microchannel. Exact solutions for the temperature distributions and velocity profile were obtained using the method of undeterminate coefficients. The Debye-Hückel linearization is used to get exact solution for the electric potential. The results showed that Brinkmann number ( Br ) , Joule heating parameter ( J ) , Debye-Hückel parameter ( Κ ) , Hartmann number ( M ) , electric field ( E z ) and suction/injection parameter ( S ) have a substantial impact on flow formation and heat transfer. Using MATLAB software, graphical simulations are provided in order to deliver a greater understanding of the influence of relevant parameters on the results achieved.

During the Stelmor air-cooling process, the temperature distribution has a significant impact on the wire loops’ final mechanical properties. The temperature distribution during air-cooling process is accurately solved by establishing three-dimensional model and numerical simulation. The heat transfer coefficient at the high dense region is much smaller than that of wire loops at the low dense region, and changes periodically over time, according to a Computational Fluid Dynamics (CFD) simulation method. It is also found that the heat transfer coefficient on the cross section of the wire loop is very different, with a difference of 70-100 Wm-2K-1. Finally, the finite difference method is used to calculate the mathematical model of the temperature distribution during the Stelmor air-cooling process. Comparing the results with the measurement data, the simulation results and measurement data match up well.

The quest for augmenting dropwise condensation heat transfer performance has been the driving force behind the exploration of innovative techniques and approaches to fulfil the desired objective. Recent literature in condensation heat transfer unveils that dropwise condensation heat transfer improvements from Slippery Liquid Infused Porous Surfaces (SLIPSs) was central to the study of several researchers because these surfaces have shown excellent droplet mobility due to extremely low adhesion between the condensing liquid and the lubricant infused surface, thereby, promote dropwise condensation. As part of supplementing current research on SLIPSs, for the first time, the present study explores the potential of a semi-solid lubricant impregnated porous surface in enhancing the condensation heat transfer performance of a vertical condenser tube. The results of experiments conducted over a wide range of subcooling (5°C ≤ ΔT ≤ 65°C) in a saturated steam environment signify that Copper tubes with semi-solid lubricant impregnated porous surfaces are potential candidates for enhancing dropwise condensation heat transfer coefficient when compared to an untreated vertical Copper condenser tube. The highest enhancement is found to be 280% at a subcooling of 40°C. Also, the semi-solid lubricant impregnated porous surfaces are proficient in sustaining dropwise condensation for a time period of 72 hours without any degradation in the heat transfer performance. The method devised here for fabricating the semi-solid lubricant impregnated surfaces is simple, less expensive, and less time-consuming compared to the techniques reported earlier for fabricating the SLIPSs. Additionally, in this work an approach based on numerical optimization by a stochastic global optimization technique, namely, Genetic Algorithm, is proposed to retrieve the coefficients and the exponent in the mathematical expression of overall resistance, which in turn is used to compute the tube-side dropwise convection heat transfer coefficient.