Source Of Radiant Energy Research Articles

Thermofluidic transport of Williamson flow in stratified medium with radiative energy and heat source aspects by machine learning paradigm

This study investigates Williamson fluid with stratification aspects through an inclined medium with radiative effects and with consideration of transversally applied magnetic field. Additionally, the study involves novel contribution of thermal generating source and chemically reactive species. Modelling is conceded by incorporating conservation laws in view of ordinary differential setup after employing similar variables. Afterwards, numerical simulations through shooting and Rk-4 procedures are executed to inspect the behavior of flow and thermosolutal distributions versus variation in key parameters. Subsequently, the collected data is evaluated by utilizing a multilayer perceptron-based ANN model. The input data for the heat flux, corresponding to different fluid model parameters, is trained by employing Levenberg-Marquardt paradigm and validated against numerical experiment results. The precision of the predicted data is assessed by calculating the mean squared error, determination coefficient and error rating scale. The magnitude of heat flux coefficient elevates up to 15 % in the existence of radiation effect, while depreciates up to 6 % in the presence of stratification effect. The implementation of ANN model depicts a mean square error value 1.36×10−3 when no heat source, which rises to 1.41×10−2 when a heat source is present. From small values of mean squared error for testing, training and validation estimated for Nusselt number ensures the performance of developed ANN network.

Bioconvective three-dimensional flow of Sutterby nanoliquid due to moving plate with activation energy applications

Owing to enhanced features of nanomaterials, various applications of such materials have been suggested in the thermal systems, heat exchanges, electronic cooling systems, coolant processes, energy production etc. Following to such motivated applications, the objective of current analysis is to presents the bioconvective double stratification flow of Sutterby nanofluid due to bidirectional moving surface. The thermal interpretation of problem is subject to utilization of radiative effects, activation energy and heat source. The observations for heat, mass and microorganism's assessment are performed by using the convective boundary conditions. Shooting numerical simulations are performed for modeled problem. It is noticed that heat transfer enhances due to thermal stratification parameter. An increment in mass transfer is subject to larger values of mass stratification Biot number. The claimed results offer significance in controlling the heating and cooling processes, thermal devices, energy generation, manufacturing developments, solar systems etc.

Determining the Effectiveness of Solar Collectors Used In Low-Radiation Areas

Background: In this paper considers the issues of using solar collectors as an alternative source of energy for territories remote from the power grids. One of the main criteria when choosing the solar collectors is the choice of the working fluid for heat transfer. Solar collectors according to the type of coolant are divided into a liquid and air. Materials and Methods: The solar collector works on the principle of energy transfer to a liquid from a source of radiant energy that is located a certain distance away, unlike conventional heat exchangers. In actual use, there are two types of solar collectors: one concentrates solar energy, the other doesn’t. Results: It is possible to give air clusters in places with low air temperature and low solar activity, and we use energy equations and their balances. Moreover, we have determined the thermal properties of solar clusters and useful energies. Conclusion: Climate characteristics and structures are crucial to the results of a solar array's efficiency in covering ocean temperatures and the types of solar arrays to choose from with good results, heat fluxes and densities. In addition, we show that the solar collector is not considered a basic criterion in choosing the types of collectors. Key words: Solar energy, sustainable energy, low-radiation, solar collector, heat transfer

Minimum entropy production in inhomogeneous thermoelectric materials

Due to their potential applications in energy production based on waste heat, direct solar radiation or other energy sources, semiconductor materials have for years attracted the attention of theoretical and experimental researchers. The focus has been on improving the performance of thermoelectric devices through several strategies and special interest has been placed on materials with spatially inhomogeneous transport properties. Inhomogeneity can be achieved in various ways, all of them leading, to a greater or lesser extent, to an improvement of the thermoelectric performance. In this paper, general linear heat and electric charge transport processes in inhomogeneous materials are addressed. The guiding idea followed here is that there exists a relationship between inhomogeneity (structuring), minimum entropy production and performance which may be fruitfully exploited for designing more efficient thermoelectric semiconductor devices. We first show that the stationary states of such materials are minimum global entropy production states. This constitutes an extension of the validity of Prigogine’s minimum entropy principle. The heat and charge transport equations obtained within the framework of classical irreversible thermodynamics are solved to find the stationary profiles of temperature and self-consistent electric potential in a one-dimensional model of a silicon–germanium alloy subjected to an external temperature difference. This allows us to assess the effect of the spatial inhomogeneity on the thermoelectric performance. We find that, regardless of the value of the applied temperature difference, the system may efficiently operate in a regime of minimum entropy production and high efficiency.

Anomalous behavior of Newtonian hydrodynamics coupled with radiation transport

This study shows that Newtonian hydrodynamics coupled with radiation transport, using a wide range of methods for treating the material-motion corrections, results in anomalous behavior. In particular, the flow of infinite-medium equilibration will accelerate whenever viewed moving past an observer in the laboratory frame. The acceleration may cause the velocity to increase exponentially in time. An exact fully-relativistic solution is derived to show that there is no acceleration, independent of the reference frame. This solution is analytic and may be used as a validation problem for the simulation of fully-relativistic radiation hydrodynamics.Current O(β)-accurate radiation treatments, where β is the velocity magnitude divided by the speed of light, also predict acceleration. But we show that the anomalous acceleration is not due to the radiation approximations, but rather from assuming that the hydrodynamics evolves on the fluid time scale, which leads to dropping terms from fully-relativistic hydrodynamics to give the Newtonian approximation. The addition of radiation energy and momentum sources to hydrodynamics introduces fast time scales, such as radiation equilibration. These fast time scales invalidate the use of Newtonian hydrodynamics for certain problems, even when β is small. Alternative formulations are discussed, but we find that removing the anomalous behavior comes at a cost, either by sacrificing conservation or accuracy.

A Review on Solar Photovoltaic Technology and Its Future Trends

A source of radiant energy is the Sun. Only a small part of the energy we receive from the Sun is actually used by us. Sunshine that reaches the surface of the Earth has the capacity to meet all of our rising energy needs. The process of converting incident sunlight energy into electrical energy is known as solar photovoltaic technology. The original generation of solar cells were made of silicon. Further advancements are required, according to research, for solar cells to operate more efficiently and to absorb large amounts of incident sunlight. To achieve these requirements, amorphous Silicon sola r cells and thin film technology were further developed. From first-generation solar cells to dye-sensitized solar cells, quantum dot solar cells, and some more current technologies, we have examined a gradual progression in solar cell technology in this review. The potential for these many generations of solar cell technologies to establish themselves is also discussed in this article. Keywords: Solar Photovoltaic, Dye sensitized solar cells, Quantum dot solar cells, Tandem solar cells, Hybrid Perovskite solar cell.

Organosulphur, organoselenium and organotellurium compounds for the development of heterogeneous and nanocatalytic systems for Suzuki coupling.

Suzuki-Miyaura cross-coupling (SMC) is an extremely useful reaction in organic syntheses. During the last two decades, many researchers across the world have employed organochalcogen compounds in various ways for the development of catalytic systems for this reaction. Chalcogen-ligated molecular complexes have been designed using such compounds as ligands, and applied as homogeneous catalytic systems. During the period 2013-2022, various heterogeneous and nano-catalytic systems have also been developed using organosulphur, organoselenium and organotellurium compounds. The main advantages associated with such systems are their easy synthesis and air- and moisture-insensitivity. This article aims to provide insights into the synthetic methodologies pertaining to the preparation of (i) these catalytically relevant and useful compounds and (ii) the heterogeneous and nano-catalytic systems designed using them. Another major focus of the article is to rationalize and critically analyse the effect of chalcogen donor on the size, composition, morphology and shape of the nanostructure. A critical analysis of the applications of all such catalytic systems in Suzuki-Miyaura coupling is presented in detail. Various factors (e.g., temperature) which affect the catalytic performance are also rationalized. The effects of binding mode, ligand framework, chalcogen donor atom and metal are also covered, along with all other factors that influence the catalytic potential of the systems. Various other aspects such as green catalysis (in aqueous medium and in air), and use of non-conventional (ultrasonic radiation) energy sources are analysed. Applications of heterogeneous and nanocatalytic systems apart from Suzuki coupling are also highlighted, and challenges and future scope are elaborated.

An Implicit Finite Volume Scheme to Solve the Time-dependent Radiation Transport Equation Based on Discrete Ordinates

Abstract We describe a new algorithm to implicitly solve the time-dependent, frequency-integrated radiation transport (RT) equation, which is coupled to an explicit solver for equations of magnetohydrodynamics (MHD) using Athena++. The radiation field is represented by specific intensities along discrete rays, which are evolved using a conservative finite volume approach for both Cartesian and curvilinear coordinate systems. All terms for spatial transport of photons and interactions between gas and radiation are calculated implicitly together. An efficient Jacobi-like iteration scheme is used to solve the implicit equations. This removes any time-step constraint due to the speed of light in RT. We evolve the specific intensities in the lab frame to simplify the transport step. The lab frame specific intensities are transformed to the comoving frame via Lorentz transformation when the source term is calculated. Therefore, the scheme does not need any expansion in terms of v/c. The radiation energy and momentum source terms for the gas are calculated via direct quadrature in the angular space. The time step for the whole scheme is determined by the normal Courant–Friedrichs–Lewy condition in the MHD module. We provide a variety of test problems for this algorithm, including both optically thick and thin regimes, and for both gas and radiation pressure-dominated flows to demonstrate its accuracy and efficiency.

Energy Harvesting Technologies for Structural Health Monitoring of Airplane Components-A Review.

With the aim of increasing the efficiency of maintenance and fuel usage in airplanes, structural health monitoring (SHM) of critical composite structures is increasingly expected and required. The optimized usage of this concept is subject of intensive work in the framework of the EU COST Action CA18203 “Optimising Design for Inspection” (ODIN). In this context, a thorough review of a broad range of energy harvesting (EH) technologies to be potentially used as power sources for the acoustic emission and guided wave propagation sensors of the considered SHM systems, as well as for the respective data elaboration and wireless communication modules, is provided in this work. EH devices based on the usage of kinetic energy, thermal gradients, solar radiation, airflow, and other viable energy sources, proposed so far in the literature, are thus described with a critical review of the respective specific power levels, of their potential placement on airplanes, as well as the consequently necessary power management architectures. The guidelines provided for the selection of the most appropriate EH and power management technologies create the preconditions to develop a new class of autonomous sensor nodes for the in-process, non-destructive SHM of airplane components.

Innovative Method of Treating Sintered Metal Powders Surfaces with Optical Radiation Pulses, Using Gas-Discharge Lamp

The research conducted in the present paper is part of a comprehensive study to innovate a method of surface treatment for some metallic powder materials with alternative energy sources to lasers and electron beams (i.e. with gas-discharge lamp (GDL)), typically used as sources of optical pumping for the lasers, having a solid active element. The radiant energy sources used for study are composed of a GDL and the high voltage power supply consists of a block of high-capacity capacitors. The materials were selected from the Fe-Cu-C grade, with a carbon content between 0.5 to 0.72%, and the measurements were made on microscopes with electron beam scanning. Configurational modifications of a surface layer of approximatively 30-35 im, characteristic for Fe-C-Cu alloys, containing nearly 0.7% C (pearlite, ferrite and cementite) are highlighted by the microscopic examinations. At the surface level, the energy flux created by the lamp in the visible spectrum, generates pressure, determining elongation of the surface layer pores, under optical action, resulting an effect comparable to plastic deformation by induration or compaction through mechanical actions. The results obtained highlight the potential of this class of materials to surface treatments and the options for the energy sources used.

Steady thermocapillary migration of a droplet in a uniform temperature gradient combined with a radiation energy source at large Marangoni numbers.

Steady thermocapillary droplet migration in a uniform temperature gradient combined with a radiation energy source at large Reynolds and Marangoni numbers is studied. To reach a terminal quasisteady process, the magnitude of the radiation energy source is required to preserve the conservative integral thermal flux across the surface. Under a quasisteady state assumption, an analytical result for the steady thermocapillary migration of a droplet at large Reynolds and Marangoni numbers is derived by using the method of matched asymptotic expansions. It is shown that the thermocapillary droplet migration speed increases as the Marangoni number increases, while a radiation energy source with a sine square dependence is provided.

Modelling of the conjugate natural convection in a closed system with the radiant heating source radiant energy distribution by Lambert’s cosine law

Various types of emitters are often used as energy sources in real engineering systems and technological processes. Investigations of heat transfer basic laws in such systems are of interest. We conducted mathematical modelling of conjugate heat transfer in a closed rectangular cavity under conditions of radiant energy source operating. The 2-D problem of conjugate natural convection in vorticity stream function-temperature dimensionless variables has been numerically solved by means of the finite difference method. Radiant energy distribution along the gas-wall interfaces was set by Lamberts? cosine law. We obtained fields of temperature and stream functions in a wide range of governing parameters (Rayleigh number 104 ? Ra ? 106, the length of radiant heating source 0.15 ? D ? 0.6). Then we analyzed how heat retaining properties of finite thickness heat conducting walls made of different materials affect the heat transfer intensity. Differential characteristics distribution showed significant non-uniformity and non-stationarity of the conjugate heat transfer process under study.

Prediction of the radiative heat transfer in small and large scale oxy-coal furnaces

Predicting thermal radiation for oxy-coal combustion highlights the importance of the radiation models for the spectral properties of gases and particles. This study numerically investigates radiation behaviours in small and large scale furnaces through refined radiative property models, using the full-spectrum correlated k (FSCK) model and Mie theory based data, compared with the conventional use of the weighted sum of grey gases (WSGG) model and the constant values of the particle radiation properties. Both oxy-coal combustion and air-fired combustion have been investigated numerically and compared with combustion plant experimental data. Reasonable agreements are obtained between the predicted results and the measured data. Employing the refined radiative property models achieves closer predicted heat transfer properties to the measured data from both furnaces. The gas-phase component of the radiation energy source term obtained from the FSCK property model is higher within the flame region than the values obtained by using the conventional methods. The impact of using non-grey radiation behaviour of gases through the FSCK is enhanced in the large scale furnace as the predicted gas radiation source term is approximately 2–3 times that obtained when using the WSGG, while the same term is in much closer agreement between the FSCK and the WSGG for the pilot-scale furnace. The predicted total radiation source term (from both gases and particles) is lower in the flame region after using the refined models, which results in a hotter flame (approximately 50–150 K higher in this study) compared with results obtained from conventional methods. In addition, the predicted surface incident radiation reduces by using the refined radiative property models for both furnaces, in which the difference is relevant with the difference in the predicted radiation properties between the two modelling techniques. Numerical uncertainties resulting from the influences of combustion model, turbulent particle dispersion and turbulence modelling on the radiation behaviours are discussed.

Numerical Modeling of Conjugate Thermogravitational Convection in a Closed System with a Radiant Energy Source in Conditions of Convective-Radiative Heat Exchange at the External Boundary

Mathematical modeling of conjugate natural convection in a closed rectangular cavity with a radiant energy source in conditions of convective-radiative heat exchange at the external boundary was conducted. The radiant energy distribution was set by the Lambert’s law. Conduction and convection processes analysis showed that the air masses flow pattern is modified slightly over the time. The temperature increases in the gas cavity, despite the heat removal from the one of the external boundary. According to the results of the integral heat transfer analysis were established that the average Nusselt number (Nuav ) increasing occurs up to τ = 200 (dimensionless time). Further Nuav has changed insignificantly due to the temperature field equalization near the interfaces “gas – wall”.

Interaction of short pulse collimated irradiation with inhomogeneity: An accurate model

The accurate formulation of radiative source is established with the transient effect of radiation transport for evaluating the correct thermal damage in the proximity of laser source. The accurate formulation of radiative source consists of two parts: the conventional absorption term and the propagation term. The inclusion of the propagation term significantly deviates the energy distribution from earlier steady state radiative source especially in the ultrashort time scale where this term has significance. In the present work, this effect has been investigated in the presence of absorbing, emitting, and anisotropically scattering medium within a two-dimensional rectangular domain subjected to collimated irradiation at one of its boundaries. A small inhomogeneity is taken at the center of the top wall which is irradiated with a laser source. The effects of optical parameters such as absorption coefficient, scattering coefficient, and scattering albedo on the temperature distribution in the medium are analyzed. It is found that the modified radiation energy flux gives an early signal of crossing the thermal damage threshold temperature surrounding the inhomogeneity. Inclusion of propagation term in radiation energy source helps to precisely access the extent of thermal damage surrounding the inhomogeneity which is not traceable as per the existing models.

Numerical Study of the Thermally Conductive Finite Thickness Walls Impact on Heat Transfer Regime in a Closed System in Conditions of Radiant Energy Supply

Plane problem of thermogravitational convection in a closed rectangular cavity is numerically solved in conditions of radiant energy supply to the one of the boundaries. Differential heat transfer parameters (fields of temperatures and stream functions) for the conjugate (only vertical walls, only horizontal, vertical and horizontal walls) and the nonconjugate formulation are obtained. Temperature distributions in the Y direction in the cross section along the axis of symmetry showed that the presence of heat-conducting finite thickness walls leads to a redistribution of the energy which is accumulated by gas and enclosure structures. In order to reduce the energy consumption for heating of the large premises it is advisable to abandon the traditional convective heating in many cases. The most promising is the use of gas infrared emitters for the local heating of the limited size areas where it is needed (1). An approach (2), which is based on the solution of the heat balance equation, is suggested for the analysis of heating systems with gas and electric infrared emitters. The algorithm (2) allows us to calculate the required number of emitters and their capacity. But the heat transfer model (2), as well as its further modification (3), is formulated without taking into account the free convection movement of air masses and the conjugation of gas and thermally conductive enclosure structures. Investigation of jointly proceeding processes of conduction and convection in a closed system with a source of radiant energy in conjugate formulation is of interest. The aim of this study is numerical investigation of the thermally conductive finite thickness walls impact on heat transfer regime in a closed system in a closed system with a source of radiant energy.

A Microcontroller-Based Active Solar Water Heating System for Domestic Applications

A potential solution to adequate and sustainable electricity supply problems in most developing countries is dependent on proper harnessing of solar (radiant) energy. Owing to the over dependence on fossil-fuel based energy, there is an exponential rise in carbon dioxide (CO2) emissions into the atmosphere, thereby causing severe environmental degradation and ozone layer depletion. This paper seeks to apply the readily available radiant energy source to solar water heating, and establish possible economic benefits to its use in domestic applications for residents of Covenant University campus. The microcontroller-based active solar water heating system (ASWHS) is designed to effectively absorb radiant energy using solar collectors, and store it as hot water in a water tank via a direct current (DC) circulation pump powered by a stand-alone photovoltaic (PV) system. The design also incorporates an auxiliary electric heater which is put to use only when there is insufficient radiant energy. A case study is reported to show the importance of the ASWHS for domestic water heating. The maximum design efficiency and the expected energy output of the solar collector throughout its working life is 79.94% and 498,225kWh respectively. A reduced dependence on grid supply and/or fossil-fuel based generator sets during hot water demand periods is recorded using the ASWHS with a high payback period of 15 years; and a lower unit cost (US$0.01/kWh) of the ASWHS makes it more economically viable as compared to the unit cost (US$0.18/kWh) of the grid supply for the same amount of energy consumed.

Ocular phototherapy

Phototherapy can be translated to mean 'light or radiant energy-induced treatment.' Lasers have become the exclusive source of light or radiant energy for all applications of phototherapy. Depending on the wavelength, intensity, and duration of exposure, tissues can either absorb the energy (photocoagulation, thermotherapy, and photodynamic therapy (PDT)) or undergo ionization (photodisruption). For phototherapy to be effective, the energy has to be absorbed by tissues or more specifically by naturally occurring pigment (xanthophyll, haemoglobin, and melanin) within them. In tissues or tumours that lack natural pigment, dyes (verteporphin, Visudyne) with narrow absorption spectrum can be injected intravenously that act as focal absorbent of laser energy after they have preferentially localized within the tumour. Ocular phototherapy has broad applications in treatment of ocular tumours. Laser photocoagulation, thermotherapy, and PDT can be delivered with low rates of complications and with ease in the outpatient setting. Review of the current literature suggests excellent results when these treatments are applied for benign tumours, particularly for vascular tumours such as circumscribed choroidal haemangioma. For primary malignant tumours, such as choroidal melanoma, thermotherapy, and PDT do not offer local tumour control rates that are equivalent or higher than those achieved with plaque or proton radiation therapy. However, for secondary malignant tumours (choroidal metastases), thermotherapy and PDT can be applied as a palliative treatment. Greater experience is necessary to fully comprehend risks, comparative benefits, and complication of ocular phototherapy of ocular tumours.

Thermal Load from a CO2Laser Radiant Energy Source Induces Changes in Corneal Surface Asphericity, Roughness, and Transverse Contraction

We examined corneal surface response to an isolated thermal load. Cadaveric porcine eyes were pressurized and stabilized for processing and imaging. A carbon dioxide (CO2) laser (1.75 W) delivered a uniform disk of continuous wave thermal radiant energy to the exposed corneal stromal surface without ablation. Thermal load was determined by measuring corneal surface temperature during CO2 laser irradiation. Corneal profilometry was measured with broad-band optical interferometry before and after CO2 laser irradiation. Photomicrographs of the stromal surface were taken before and after irradiation, and the images were superimposed to examine changes in positional marks, examining mechanical alterations in the stromal surface. Thermal load from uniform laser irradiation without ablation produces central corneal steepening and paracentral flattening in the central 3-mm diameter. Q values, measuring asphericity in the central 2 mm of the cornea increased significantly and it was correlated with the temperature rise (R2=0.767). Surface roughness increased significantly and also was correlated with temperature rise (R2=0.851). The central stromal surface contracted and underwent characteristic morphologic changes with the applied thermal load, which correlated well with the temperature rise (R2=0.818). The thermal load created by CO2 laser irradiation creates a characteristic spectrum of morphologic changes on the porcine corneal stromal surface that correlates to the temperature rise and is not seen with inorganic, isotropic material. The surface changes demonstrated with the CO2 laser likely are indicative of temperature-induced transverse collagen fibril contraction and stress redistribution. Refractive procedures that produce significant thermal load should be cognizant of these morphologic changes.

A massively parallel solution strategy for efficient thermal radiation simulation

A novel and efficient methodology to solve the Radiative Transfer Equations (RTE) in thermal radiation is discussed. The BiCGStab(2) iterative solution method, as designed for the non-symmetric linear equation systems, is used to solve the discretized RTE. The numerical upwind and central schemes are blended to provide a stable numerical scheme (MUCS) for interpolation of the cell facial radiation intensities in finite volume formulation. The combination of the BiCGStab(2) and MUCS methods proved to be very efficient when coupling with the DOM approach to solve the RTE. A cost-effective tabulation technique for the gaseous radiative property model SNB-FSCK using 7-point Gauss-Labatto quadrature scheme is also introduced. The whole methodology is implemented into a massively parallel unstructured CFD code where the radiative and fluid flow solutions share the same domain decomposition, which is the bottleneck in current radiative solvers. The dual mesh decomposition at the cell groups level and processors level is adopted to optimize the CFD code for massively parallel computing. The whole method is applied to simulate the radiation heat-transfer in a 3D rectangular enclosure containing non-isothermal CO2 and H2O mixtures. Two test cases are studied for homogeneous and inhomogeneous distributions of CO2 and H2O in the enclosure. The result is reported for the heat flux and radiation energy source and the comparison is also made between the present methodology BiCGStab(2)/MUCS/tabulated SNB-FSCK, the benchmark method SNB-CK (implemented at 25cm−1 narrow-band) and some other methods available in the literature. The present method (BiCGStab(2)/MUCS/tabulated SNB-FSCK) yields more accurate predictions particularly for the radiation source term. When comparing with the benchmark solution, the relative error of the radiation source term is remarkably reduced to less than 4% and the CPU time is drastically diminished.