Numerical study of perforated obstacles effects on the performance of solar parabolic trough collector

The current work presents and discusses a numerical analysis of improving heat transmission in the receiver of a parabolic trough solar collector by introducing perforated barriers. While the proposed approach to enhance the collector’s performance is promising, the use of obstacles results in increased pressure loss. The Computational Fluid Dynamics (CFD) model analysis is conducted based on the renormalization-group (RNG) k-ɛ turbulent model associated with standard wall function using thermal oil D12 as working fluid The thermo-hydraulic analysis of the receiver tube with perforated obstacles is taken for various configurations and Reynolds number ranging from 18,860 to 81,728. The results are compared with that of the receiver without perforated obstacles. The receiver tube with three holes (PO3) showed better heat transfer characteristics. In addition, the Nusselt number (Nu) increases about 115% with the increase of friction factor 5–6.5 times and the performance evaluation criteria (PEC) changes from 1.22 to 1.24. The temperature of thermal oil fluid attains its maximum value at the exit, and higher temperatures (462.1 K) are found in the absorber tube with perforated obstacles with three holes (PO3). Accordingly, using perforated obstacles receiver for parabolic trough concentrator is highly recommended where significant enhancement of system’s performance is achieved

Cross electromagnetic nanofluid flow examination with infinite shear rate viscosity and melting heat through Skan-Falkner wedge

This demonstration of study focalizes the melting transport and inclined magnetizing effect of cross fluid with infinite shear rate viscosity along the Skan-Falkner wedge. Transport of energy analysis is brought through the melting process and velocity distribution is numerically achieved under the influence of the inclined magnetic dipole effect. Moreover, this study brings out the numerical effect of the process of thermophoresis diffusion and Brownian motion. The infinite shear rate of viscosity model of cross fluid reveals the set of partial differential equations (PDEs). Similarity transformation of variables converts the PDEs system into nonlinear ordinary differential equations (ODEs). Furthermore, a numerical bvp4c process is imposed on these resultant ODEs for the pursuit of a numerical solution. From the debate, it is concluded that melting process cases boost the velocity of fluid and velocity ratio parameter. The augmentation of the minimum value of energy needed to activate or energize the molecules or atoms to activate the chemical reaction boosts the concentricity inclined magnetized flow, infinite shear rate viscosity, Brownian motion, 2-D cross fluid, melting process of energy, thermophoresis diffusion melting of energy.Campus Chiclay

FTn Finite Volume Analysis of Ultrafast Laser Radiation Transport through Human Skin Cancer

In this work, we develop a numerical tool for the early detection of skin cancer using a 3D numerical transient radiative heat transfer study of ultrafast-laser transport through normal and malignant human skins. The curved-line advection method (CLAM) spatial scheme and the FTn angular scheme of the finite volume method (FVM) are investigated to analyze the above-cited physical phenomena. Both Fresnel specular and diffuse boundary conditions are analyzed. Human skin is considered based on optical properties available from other sources. The temporal radiative signals of skin with malignancies were compared to those of normal skin. Malignancies in the basal layer and epidermis were simulated. Further, the effects of laser light wavelength and the volume of the cancerous region and its scattering coefficient on these signals were studied. The results show that (1) the effect of the Fresnel boundary in the modeling was pronounced; (2) the peak magnitude for human skin with the cutaneous melanoma (CM) had the maximum value in comparison with those obtained for the two other malignancies; and (3) when cancer fully affected the living epidermis with any of these malignancies, the reflectance was more than its predicted value when affected by the basal only

Modeling of Radiative Heat Transfer in 2D Complex Heat Recuperator of Biomass Pyrolysis Furnace: A Study of Baffles Shadow and Soot Volume Fraction Effects

International audienceThe radiative heat transfer problem is investigated numerically for 2D complex geometry biomass pyrolysis reactor composed of two pyrolysis chambers and a heat recuperator. The fumes are a mixture of carbon dioxide and water vapor charged with absorbing and scattering particles and soot. In order to increase gases residence time and heat transfer, the heat recuperator is provided with many inclined, vertical, horizontal, diffuse and grey baffles of finite thickness and has a complex geometry. The Finite Volume Method (FVM) is applied to study radiative heat transfer. The blocked-off region procedure is used to treat the geometrical irregularities. Eight cases are considered in order to demonstrate the effect of adding baffles on the walls of the heat recuperator and on the walls of the pyrolysis rooms then choose the best case giving the maximum heat flux transferred to the biomass in the pyrolysis chambers. Ray effect due to the presence of baffles is studied and demonstrated to have a crucial effect on radiative heat flux on the walls of the pyrolysis rooms. Shadow effect caused by the presence of the baffles is also studied. The non grey radiative heat transfer is studied for the real existent configuration. The Weighted Sum of The Grey Gases (WSGG) Model of Kim and Song is used as non grey model. The effect of soot volumetric fraction on the non grey radiative heat flux is investigated and discussed

Lattice Boltzmann simulation of natural convection in an L-shaped enclosure in the presence of nanofluid

In the present paper, fluid flow and heat transfer inside L-shaped enclosure filled with Cu/water nanofluid has been investigated numerically using the Lattice Boltzmann Method. The validity of the numerical code used is ascertained and good agreement was found with published results. The effects of different parameters such as Rayleigh number (103–106), aspect ratio of the L-shaped enclosure (0.2–0.6) and nanoparticle volume concentration (0–0.05) on the flow and temperature fields are studied. The obtained results show that nanofluid enhances the heat transfer amount and reducing the aspect ratio improves this effect. Also it was found that the mean Nusselt number increased with increase in Rayleigh number

Nanoencapsulated phase change material in a trapezoidal prism wall under the magnetic field effect for energy storage purposes

Abstract Recently, Nano-encapsulated phase change materials (NEPCM) have attracted the attention of researchers due to their promising application in thermal management. This research investigates magnetohydrodynamic mixed convection of NEPCM contained within a lid-driven trapezoidal prism enclosure containing a hot-centered elliptical obstacle. The upper cavity wall is moving at a constant velocity; both inclined walls are cold, while the rest of the walls are insulated. The Galerkin Finite Element Method was used to solve the system's governing equations. The influence of Reynolds number (Re 1–500), Hartmann number (Ha = 0–100), NEPCM volumetric fraction φ (0–8%), and elliptical obstacle orientation α (0–3π/4) on thermal fields and flow patterns are introduced and analyzed. The results indicated that the maximum heat transfer rate is observed when the hot elliptic obstacle is oriented at 90°; an increment of 6% in the Nu number is obtained in this orientation compared to other orientations. Reducing Ha from 100 to 0 increased Nu by 14%. The Maximum value of the Bejan number was observed for the case of Ha = 0, α = 90° and φ = 0.08

Investigation of phase change heat transfer in a rectangular case as function of fin placement for solar applications

This paper attempts to maximize solar energy utilization by employing a latent heat thermal energy storage (LHTES) unit integrated with a solar receiver of concentrating collectors or thermal management unit for photovoltaic panels. The study investigated an LHTES unit with a rectangular shape and equipped with a T-shaped fin subjected to heat flux. The paper examined the effect of eight T-fin positions under the applied heat flux on the thermal performance of phase change material (PCM). The PCM melting process was modeled using the enthalpy-porosity method using the finite element approach. The obtained numerical results revealed that PCM melting rate strongly depends on fin position, with superiority for fins located at the upper part of the chamber when heat flux is used as the primary heating source. Under applied heat flux, locating the fin at the upper section of the vertical LHTES unit enhanced the melting rate of the PCM, reaching 10 % better than the fin's middle and bottom positions, which is against the cases reported for the fixed temperature heating process that prefer bottom fins. Thus, these results recommend using T-shaped fins in the upper parts of PCM-based units used for solar collector receivers and thermal management of photovoltaic panels

Numerical Study of Lid-Driven Hybrid Nanofluid Flow in a Corrugated Porous Cavity in the Presence of Magnetic Field

The lid-driven top wall’s influence combined with the side walls’ waviness map induce the mixed convection heat transfer, flow behavior, and entropy generation of a hybrid nanofluid (Fe3O4–MWCNT/water), a process analyzed through the present study. The working fluid occupies a permeable cubic chamber and is subjected to a magnetic field. The governing equations are solved by employing the GFEM method. The results show that the magnetic force significantly affects the working fluid’s thermal and flow behavior, where the magnetic force’s perpendicular direction remarkably improves the thermal distribution at Re = 500. Also, increasing Ha and decreasing Re drops both the irreversibility and the heat transfer rate. In addition, the highest undulation number on the wavy-sided walls gives the best heat transfer rate and the highest irreversibility

Improving the thermal-hydraulic performance of parabolic solar collectors using absorber tubes equipped with perforated twisted tape containing nanofluid

The thermal and hydraulic efficiency of a parabolic trough solar collector is investigated in this study. The collector absorber tube is equipped with twisted tape with circular holes containing water-copper oxide nanofluid with three nanoparticles volume fractions of 1%, 2% and 4%. In three modes (d/W = 0.5, 0.7, 0.9), circular holes are constructed for the ratio of the circle's diameter to the twisted tape's breadth. All turbulent flow simulations were done using the SIMPLEC algorithm, FVM and RNG k-ε model in three Reynolds numbers as 10,000, 20,000 and 30,000. Studies have shown inserting twisted tape with a circular hole increases the pressure drop and the heat transfer rate compared to a pipe without twisted tape. The highest coefficient of thermal performance occurs in Reylond number of 10,000 and a nanoparticles volume fraction of 4%. The findings indicate that using nanoparticles improves the solar collector's energy and exergy efficiency. As a result, the best collector performance was obtained when using nanofluids with an nanoparticles volume fraction of 4%.The Deanship of Scientific Research at King Khalid University, Abha, Saudi Arabia.http://www.elsevier.com/locate/seta2024-04-11hj2023Mechanical and Aeronautical Engineerin