Absorption Of Thermal Radiation Research Articles

Irreversibility analysis for unsteady slip flow of heat absorptive liquid with multiple mass diffusion of nanomaterials over a permeable vertical moving plate: A comparative study

This study looks at how thermal radiation and magnetic fields affect the generation of entropy in the unsteady flow of a tri-hybridized nanofluid across a plate that is moving vertically and has surface slippage and suction that changes over time. The movement of the plate aligns with fluid flow, and the far-away velocity increases exponentially following the small perturbation rule. The unsteadiness of the flow is attributed to the varying free stream velocity. A homogeneous magnetic flux acting transversely to the porous wall regulates the laminar and incompressible two-dimensional flow. The presence of tri-hybridized nanoparticles makes it possible to study how adding nanoparticles with different thermal properties, such as Cu, Fe3O4 and TiO2 changes the way base fluids like water and kerosene flow and how heat moves through them. Using dimensionless variables, the mathematical model of the problem is transformed into a form amenable to an analytical solution. The solution is achieved with the help of two-term harmonic and non-harmonic functions. Several factors that influence fluid flow and heat transmission are examined and explored in depth. These include plate velocity, slippage parameter, nanoparticle volume fraction, thermal radiation and heat absorption. The findings show that ternary nanoparticles raise the temperature and speed of both water and kerosene more than hybrid nanoparticles. The increase in the volume fraction of nanomaterials also increases the temperature and velocity of both fluids. These results might be used to improve the efficiency of thermal management systems in a wide range of technical and industrial operations having heat transfer and fluid movement.

Soret and Dufour effects on two dimensional steady MHD flow past a semi‐infinite vertical porous plate in the presence of thermal radiation and radiation heat absorption with constant heat and mass flux

AbstractThe problem of a two‐dimensional steady, MHD convective, incompressible, viscous flow past a uniformly moving semi‐infinite vertical porous plate embedded in a porous medium in the presence of radiation heat absorption, thermal radiation, thermal diffusion, and diffusion thermo effects with constant heat and mass flux are studied. In the fluid region, a transversely oriented, homogeneous magnetic field of intensity is applied. The non‐dimensional governing equations are solved analytically adopting asymptotic series expansion method. The impacts of several physical quantities including Grashof number, Schmidt number, Prandtl number, Soret number, radiation absorption, radiation parameter, magnetic field within the flow domain and transport characteristic have been explored graphically. It has been found that fluid velocity and skin friction fall with enhancing the values of magnetic parameter. Further, temperature and concentration fields rise with an increase in the Soret effect.

Experimental and numerical study on earthquake-fire coupling failure mechanism of steel cylindrical tanks

An earthquake-triggered fire domino scenario (E-FDS) is an example of a typical multi-hazard coupling event. The seismic damage can affect the fire resistance of engineering structures, leading to significant mutually amplified phenomena. In this work, a two-stage experimental program is designed to expound the earthquake-fire coupling failure mechanism of steel cylindrical tanks (SCTs). Quasi-static tests are adopted to simulate the damage characteristics of SCTs under seismic excitation (Stage I). Fire tests are adopted to investigate the fire-resistance performance of pre-damaged SCTs (Stage II). The influences of seismic damage on the fire resistance of SCTs are particularly of interest. Three potential seismic damage degrees are considered. The experimental results show that tank specimens exhibit typical diamond-shaped buckling after Stage I. The coupling failure analysis of SCTs is conducted through sequential thermodynamic coupling simulations. Due to factors such as geometric deformation, residual stress, and thermal radiation absorption capacity, the fire resistance of SCTs is significantly attenuated by seismic damage. For the three damage states, fire resistance time attenuation coefficients (0.868, 0.716, 0.511) and critical temperature attenuation coefficients (0.910, 0.779, 0.672) were obtained. This work provides pivotal insights into the mutually amplified phenomena in E-FDSs.

Thermal radiation effect on the Maxwell graphene based nanofluid passing through a squeezing channel

This article presents a comparative analysis of flow and heat transfer characteristics of magnetohydrodynamic flow of non-Newtonian base fluid (ethylene glycol) and nanofluid (ethylene glycol + graphene) between two parallel plates moving toward/apart to each other. The study also includes the effects of Joule dissipation, thermal radiation, and heat absorption. The mathematical model that governs the flow of the above-described problem is a single-phase flow model for nanofluids that is augmented with the non-Newtonian Maxwell fluid model. Similarity transformation was used to change controlling partial differential equations into coupled nondimensional ordinary differential equations. The numerical solution is obtained by employing the shooting technique along with fourth order Runge–Kutta Fehlberg method. The impact of several physical characteristics on fluid velocity, temperature, the coefficient of skin friction, and the heat transfer rate is also explored. As a result, this research has the potential to be used in biomedical engineering as well as powder technology.

Multiphase hybrid model and thermal insulation simulation of elytra-mimetic ceramic fiber aerogel

In our previous work, the coaxial electrostatic spinning method was applied to construct nanofiber/SiBCN ceramic aerogel with an elytra-mimetic structure. The material presented excellent mechanical, insulation, oxidation resistance, and other properties. Based on preliminary experiments and literature reports, the integrated heat transfer behavior of nanofiber/SiBCN composite ceramic aerogels in high-temperature environments was affected by several factors, such as coaxial fiber size properties, fiber particle content, interactions, and spatial distribution. Moreover, the above factors overlapped and interacted with each other, and it was hard to generalize a clear law of action through traditional experiments and characterization. Therefore, the paper constructed a representative volume unit (RVE) model based on the complex spatial distribution characteristics of composite aerogels, using fractal theory, Rosseland equation theory, and multiphase model theory. This paper investigated the fiber and particle content, the size characteristics of the coaxial fibers, and the overall heat transfer process in high-temperature environments using the finite element method. The finite element simulated the effective thermal conductivity of multiphase aerogel composites under multiple parameters, such as fiber occupancy, fiber core-shell diameter ratio, temperature, and heat transfer mode. We obtained the property parameters of the complex composition of the material through fractal theory. The model was combined with finite elements to study the fiber particle content, the size characteristics of coaxial fibers, and the integrated heat transfer process in high-temperature environments. The fibers improved the absorption and reflection of thermal radiation with increasing fiber mass fraction, leading to improved ability of ceramic fiber aerogel to extinguish light. The fibers had a larger area to absorb and reflect thermal radiation. Based on the excellent extinction ability of SiC fibers, the composite ceramic aerogel had improved thermal performance at a specifically fiber-to-shell diameter ratio through a comprehensive multifactor simulation analysis.

High temperature oxides for selective absorption of thermal radiation

Most high melting temperature oxides are translucent in the visible-infrared region characteristic of the blackbody thermal radiation at high temperatures. Consequently, over this broad-band spectral region, the “thermal radiation window”, they do not absorb thermal radiation. Translucent oxides, such as the zirconates, can be extensively doped with rare-earth (RE) ions (Nd, Sm, Er, Dy, Yb) to achieve selective spectral absorption, and the doped oxides exhibit low thermal conductivity. The optical absorption bands are due to electronic transitions between electronic states associated with the rare-earth ions and are relatively insensitive to other rare-earth ions within the same compound. Therefore, mixed rare-earth compounds exhibit optical absorption characteristic of the sum of the individual ions’ absorptions. By contrast, the thermal conductivity of the RE zirconates is shown to be relatively independent of composition suggesting that their optical properties in the thermal radiation window regions can be modified without affecting their thermal conduction properties.

Optimizing broadband metamaterial absorber using deep reinforcement learning

Optimization of the geometry of broadband metamaterial absorbers is crucial for improving the performance of optoelectronic devices. However, a large number of geometric parameters should be considered to achieve broad absorption, which is time-consuming. Herein, we propose a rapid and simple method for optimizing metamaterial absorbers dedicated to thermal radiation absorption using deep reinforcement learning. Deep reinforcement learning generated an ideal geometry for a broadband metamaterial absorber after 4 h, demonstrating the effectiveness of this technique for the rapid and effective optimization of metamaterial absorbers.

Thermodynamic characteristics of the hot-temperature cavity generated by the spark discharge in saline water

Spark discharge in saline water can generate cavity oscillating violently. However, the thermodynamic characteristics of such a cavity is still unclear owing to the complex mechanism behind it. In this study, a systematic model is developed with the considerations of thermal radiation and mass transport, which can successfully evaluate the thermodynamic properties of the spark-induced cavity in saline water. The physical parameters related to the mass transport are identified by comparing with the experimental measurements. By using the validated parameters, we find that the thermal radiation and the condensation process cannot be ignored, and the number of water molecule increases at the first collapse point. In addition, the maximum cavity size increases with increasing absorption of thermal radiation, but decreases when the condensation coefficient increases. Increasing the discharge energy and ambient temperature are found to help generate larger cavity. The inner temperature and pressure at the collapse phase increases with the increase of the discharge energy, whereas decreases when the ambient temperature increases. Furthermore, the minimum temperature at the first maximum size is up to 3000 K under 0.1 MPa, and reaches 8000 K when the ambient pressure is larger than 1 MPa. Thus, we believe the spark-induced cavity in saline water is hot, at least during the first oscillation cycle.

Convective heat and mass transfer rate on 3D Williamson nanofluid flow via linear stretching sheet with thermal radiation and heat absorption

A mathematical analysis is communicated to the thermal radiation and heat absorption effects on 3D MHD Williamson nanoliquid (NFs) motion via stretching sheet. The convective heat and mass boundary conditions are taken in sheet when liquid is motion. As a novelty, the effects of thermal radiation, heat absorption and heat and mass convection are incorporated. The aim is to develop heat transfer. Williamson NFs are most important source of heat absorption, it having many significant applications in “energy generation, HT, aircraft, missiles, electronic cooling systems, gas turbines” etc. The suitable similarity transformations have been utilized for reduce basic governing P.D. E’s into coupled nonlinear system of O.D. E’s. Obtained O.D. Es are calculated by help of R–K–F (“Runge–Kutta–Fehlberg”)4th order procedure with shooting technique in MATLAB programming. We noticed that, the skin friction coefficient is more effective in Williamson liquid motion when compared with NFs motion with higher numerical values of stretching ratio parameter, Williamson liquid motion is high when compared to NFs motion for large values of magnetic field. We compared with present results into previous results for various conditions. Finally, in the present result is good invention of previous results.

Convective Conditions on 3D Magnetohydrodynamic (MHD) Non-Newtonian Nanofluid Flow with Nonlinear Thermal Radiation and Heat Absorption: A Numerical Analysis

Three-dimensional flow of non-Newtonian nanofluid with nonlinear thermal radiation and heat absorption is established numerical analysis. We are taken that, the nonlinear thermal radiation and heat absorption on porous stretching sheet. Moreover, we have to consider the Magnetohydrodynamic and convective conditions within the fluid motion on stretching surface. The similarity variables are implemented to translate the nonlinear PDE into a set of coupled system of ODE which are solved numerically via RKF (“Runge-Kutta-Fehlberg”) 4th order based on shooting procedure. We obtained the dimensionless parameters on velocity, temperature and concentration profiles and as well as skin friction coefficient, Nusselt number and Sherwood numbers are discussed through graphs. In this study, we found interesting results, that is the non-Newtonian fluids is most significant on velocity, temperature, and heat transfer rate is high significant in non-newtonian case when compared with nanofluid case with various statistical values of Pr (“Prandtl number”), θw (“Temperature ratio parameter”) and Nt (“Thermophoresis parameter”), respectively.

Heat and mass transfer through MHD Darcy Forchheimer Casson hybrid nanofluid flow across an exponential stretching sheet

AbstractRecent research has reported on the energy and mass transition caused by Casson hybrid nanofluid flow across an extended stretching sheet. Thermal and velocity slip conditions, heat absorption, viscous dissipation, thermal radiation, the Darcy effect, and thermophoresis diffusion have all been considered in the study of fluid flow. Fluid flow is subjected to an angled magnetic field to control the flow stream. Cu and Al2O3 NPs are dispensed into the Casson fluid to create a hybrid nanofluid (blood). The suggested model of flow dynamics is an evolving nonlinear system of PDEs, which is then reduced to a system of dimensionless ODEs using similarity proxies. The resulting set of ODEs is solved using the analytical program “HAM” for further processing. However, it has been found that the effects of the suction parameter and Darcy Forchhemier considerably reduced the energy transference rate of hybrid nanoliquids. It has been discovered that the effects of thermal radiation and heat absorption increase the energy transfer rate. Furthermore, the velocity and energy transmission rate are noticeably amplified by the dispersion of copper and cobalt ferrite nanoparticles in the base fluid.

Insight into free convection of an unsteady flow of kerosene conveying copper nanoparticles subject to thermal radiation

The present article deals with the analysis of the enhanced heat transport phenomenon due to the interaction between radiative heat and heat absorption in the time-dependent flow of nanofluid past a semi-infinite flat plate embedding within a permeable medium. The inclusion of a magnetic field also strengthens the profiles. Because of today’s need in several industries and biological fluids such as radiotherapy, peristaltic flow of blood pumping, drug delivery system, etc. the application of nanofluid is vital. Therefore, the implementation of thermal radiation and heat absorption plays an important role. The transformation of the dimensional governing equations needs various non-dimensional quantities and variables and the perturbation technique is deployed with the suitable choice of perturbation parameter. These transformed equations are handled analytically and the variation of the characterising parameters is illustrated graphically for the different values setting their range as cited in the literature. Furthermore, the important outcomes are thinning in the velocity bounding surface thickness is obtained for the augmentation in the resistive force of magnetic field within a permeable medium; , nanoparticle concentration and the magnetic parameter enhance the shear rate coefficient.

Fully Coupled Three-Dimensional Simulation of Downward Flame Spread over Combustible Material.

Three-dimensional simulations of laminar flame propagating downwards the vertical surface of a rigid polyurethane slab heated by a radiative panel are presented and compared with the measurement data. The gas-phase model (ANSYS Fluent) allows for finite-rate volatile oxidation, soot formation and oxidation, emission, transfer, and absorption of thermal radiation. The solid-phase model Pyropolis considers heat transfer across the material layer and generation of combustible volatiles in thermal decomposition of the material. Kinetic model of material decomposition is derived to obey the microscale combustion calorimetry data for different heating rates. Transient behavior of propagating flame and pyrolysis zone, as well as spatial distributions of heat flux components, temperature, and mass burning rates over the specimen surface are examined. Variation of the thermal properties of the material during its thermal decomposition, as well as the specimen surface emissivity and reradiation are shown to be the important issues strongly affecting model predictions. Two distinct modes of counterflow flame spread, thermal and kinetic, are identified. In the thermal mode corresponding to fast chemistry in the gaseous flame, the flame propagation velocity is governed by the heating rate of the combustible material ahead of the flame front. Alternatively, in the kinetic mode, it is limited by the burning velocity of the volatile-air mixture forming ahead of the flame front. Simulation results are favorably compared with the measured propagation velocity.

Numerical Investigation of the Temperature Field Effect on the Mechanical Responses of Conventional and Cool Pavements.

Conventional asphalt pavement has a deep surface color and large thermal inertia, which leads to the continuous absorption of solar thermal radiation and the sharp rise of surface temperature. This can easily lead to the permanent deformation of pavement, as well as aggravate the urban heat island (UHI) effect. Cool pavement with a reflective coating plays an important role in reducing pavement temperature and alleviating the UHI effect. It is of great significance to study the influence of temperature on the mechanical response of different types of pavement under vehicle loading. Therefore, this study examined the heat exchange theory between pavement and the external environment and utilized the representative climate data of a 24 h period in the summer. Two kinds of three-dimensional finite element models were established for the analysis of temperature distribution and the mechanical responses of conventional pavement and cool pavement. The results show that in this environmental condition, conventional pavement temperatures can exceed 50 °C under high temperatures in summer, which allows for the permanent deformation of pavement and further affects the service life of asphalt pavement. The temperature difference in a conventional pavement surface between 6 h (24.7 °C) and 22 h (30.2 °C) is much less than that between 22 h (30.2 °C) and 13 h (50.1 °C) in the summer. However, the difference in the vertical displacements of the pavement surface between 6 h and 22 h is much larger than that between 22 h and 13 h. One reason is that the difference in temperature distribution between the morning and night leads to changes in pavement structure stiffness, resulting in significant differences in vertical displacement. Cool pavement has a significant cooling effect, which can reduce the surface temperature of a road by more than 15 °C and reduce the vertical displacement of the pavement by approximately 11.3%, which improves the rutting resistance of the pavement. However, the use of cool pavement will not change the horizontal strain at the bottom of the asphalt base and will not improve the fatigue resistance of asphalt pavement. This research will lay the foundation for further clarifying the difference in the mechanical properties between the two types of pavements in the management and maintenance stage.

ABSORPTION CHARACTERISTICS OF THERMAL RADIATION FOR CARBON DIOXIDE

The article presents graphs of absorption of thermal radiation as a function of the mass of absorbing carbon dioxide per unit of illuminated area. Experimental research was preceded by an analysis of a simplified model of radiation absorption, paying attention to the phenomenon of saturation. The results of the experimental research were compared with the theoretical ones and the discrepancies were interpreted. Based on the conclusions, suggestions were made regarding the impact of further CO2 emissions on climate change.

Magnetic mixed convection confined two-sided wavy enclosures having two-sided lid-driven walls containing obstacles with thermal radiation

The present research provides numerical handling of a laminar flow mixed-radiation interaction convection heat transfer within two-sided wavy enclosures containing adiabatic obstacles. The convection process is due to the movements of the enclosure side walls together with the difference in temperature and density. Two designs of the flow domain are recognized, namely, a wavy enclosure containing a square obstacle (D1) or including a cylindrical obstacle (D2). Both the flow domain and the magnetic field are inclined with different angles and impacts of the thermal radiation and heat absorption(generation) are conducted. The Galerkin Finite Element Method associated with the Characteristic-Based Split approach is utilized to solve the governing system. The prime outcomes detected that the growth of the radiation and heat generation parameters enhances the convective process. Also, the increase in the magnetic parameter causes a dominance of the nanofluid friction irreversibility compared to the heat transfer one.

Combined Influence of Thermal Radiation, ThermoDiffusion, Radiation Absorption on Mixed Convective Heat and Mass Transfer Flow of a Micropolar Fluid in a Vertical Channel with Variable Temperature in the presence of Heat Sources

The purpose of the present chapter is to analyze the thermal radiation, radiation absorption and thermo-diffusion on mixed convective heat and mass transfer flow of a micropolar fluid between two vertical parallel plates with varying temperature in the presence of heat sources. Such type of study may be applicable in nuclear reactors, heat exchangers and various electronic devices. The non-linear governinmg equations have been solved by employing Galerkin finite element technique with three nodded line segments.The velocity ,micro-rotation temperature and concentration have been analysed for different variations of Rd,Sr,Q1 , and p

CUMULATIVE IMPACT OF VISCOUS DISSIPATION AND HEAT GENERATION ON MHD DARCY-FORCHHEIMER FLOW BETWEEN TWO STRETCHABLE DISKS: QUASI LINEARIZATION TECHNIQUE

This research describes the irreversibility analysis of steady flow with magnetic effects between two infinite stretching disks situated in a Darcy-Forchheimer medium. The energy equation is amended by the features of thermal radiation and heat absorption or generation. Similarity transformations are employed to transform the formulated equations into dimensionless form. Quasi linearization technique with the application of mathematical computational software MATLAB is used to acquire the numerical solution of these non-dimensional modeled equations. It is noticed that Eckert number, heat generation/absorption and Forchheimer parameter accelerate the temperature, while the radiation parameter decreases the temperature. It can also be observed that axial velocity is affected by inertia as well as porosity of the medium. Moreover, skin friction coefficient is an escalating function of porosity, magnetic and Forchheimer parameters.

Low-emittance copper-coating system using atomic-layer-deposited aluminum oxide

• First thermal radiative measurement of copper with thin-film aluminum oxide coating. • Thin-film aluminum oxide coating preserves the low thermal emissivity of copper. • Analysis of dielectric thin-film coating on highly reflective metallic surfaces. Copper, due to its unique properties, has a huge technological importance to our society. However, the oxidation of copper remains an issue in numerous application areas. This is especially the case in visible and IR-band optics, where even minuscule oxide layers degrade the thermo-optical properties of copper surfaces. A solution possibly resides in the application of protective coatings, which can simultaneously impair the low thermal emittance of bare copper surfaces. The present paper examines the use of thin Al 2 O 3 layers as a protective coating for copper. Al 2 O 3 layers with thickness of 4.5, 9.1, 18.5 or 28.3 nm were deposited on polished copper discs using atomic layer deposition (ALD). The total hemispherical emissivity and absorptivity of these coated copper discs were measured from 20 K up to room temperature. The emissivity and absorptivity of the copper with ALD-deposited Al 2 O 3 layers increased with rising temperature and layer thickness. Nonetheless, the observed values stayed below 1.8%, allowing the use of the coated copper in systems where low emission or absorption of thermal radiation is needed. Alongside the experiments, we present a computer-based analysis and interpretation, which may be generally applied for prediction of temperature-dependent emittance of metallic surfaces coated with a thin polar dielectric layer.

Newtonian Heating Effect on Heat Absorbing Unsteady MHD Radiating and Chemically Reacting Free Convection Flow Past an Oscillating Vertical Porous Plate

In this article, we have discussed in detail the effect of Newtonian heating on MHD unsteady free convection boundary layer flow past an oscillating vertical porous plate embedded in a porous medium with thermal radiation, chemical reaction and heat absorption. The governing PDEs of the model together with related initial and boundary conditions have been solved numerically by the finite element method. The dimensionless velocity, temperature and concentration profiles are analyzed graphically due to the effects of key parameters in the concerned model problem. Computed results for the skin friction coefficient, Nusselt number and Sherwood number are put in tabular form. It is observed that the thermal and mass buoyancy effects support the velocity whilst a reverse effect is noticed when the strength of the magnetic field is increased. The velocity and temperature enhances with an increase in the Newtonian heating and thermal radiation whilst a reverse effect is observed with an increase in the Prandtl number and heat absorption parameter. Increasing Schmidt number and chemical reaction parameter tends to depreciate both velocity and concentration. The Newtonian heating, thermal radiation and magnetic field tends to decrease in the skin friction. The Nusselt number increases with increasing Newtonian heating and heat absorption parameters. An increase in the Schmidt number and chemical reaction rate tends to improve the Sherwood number.