Presence Of Heat Research Articles

The stress and strain components for a weakened elastic plate by two curvilinear holes in presence of heat

The stress and strain components for a weakened elastic plate by two curvilinear holes in presence of heat

Nonlinear EHD Instability of Two-Superposed Walters’ B Fluids Moving through Porous Media

The current work examines the application of the viscous potential flow to the Kelvin-Helmholtz instability (KHI) of a planar interface between two visco-elastic Walters’ B fluids. The fluids are fully saturated in porous media in the presence of heat and mass transfer across the interface. Additionally, the structure is pervaded via a uniform, normal electrical field in the absence of superficial charges. The nonlinear scheme basically depends on analyzing the linear principal equation of motion, and then applying the appropriate nonlinear boundary-conditions. The current organization creates a nonlinear characteristic equation describing the amplitude performance of the surface waves. The classical Routh–Hrutwitz theory is employed to judge the linear stability criteria. Once more, the implication of the multiple time scale with the aid of Taylor theory yields a Ginzburg–Landau equation, which controls the nonlinear stability criteria. Furthermore, the Poincaré–Lindstedt technique is implemented to achieve an analytic estimated bounded solution for the surface deflection. Many special cases draw upon appropriate data selections. Finally, all theoretical findings are numerically confirmed in such a way that ensures the effectiveness of various physical parameters.

Application of a high-order MP scheme to computation of multi-phase flows with heat and mass transfer

Reliable prediction of unsteady multiphase flows with mass changes, large density ratios, and complex flow features is very challenging due to the need to accurately resolve both complex interface deformations and steep gradients associated with material interfaces. This paper describes an application of our recently developed high-order monotonicity preserving (MP) scheme – a reliable and robust scheme for long-term computations of flows contain complex smooth structures interspersed with discontinuities (Ha and Lee, 2020) − to the solution of unsteady incompressible two-phase flows in the presence of heat and mass changes. The flow is governed by the multiphase Navier–Stokes equations, which comprises of the mixture continuity equation, the mixture momentum equations, the mixture energy equation, and the continuity equation for the individual phase. The numerical discretization is implemented on generalized curvilinear grids for facilitating flow simulations of the complex geometries. Our high-order MP scheme is applied to the calculations of the convective and surface tension terms. To obtain an effectively simultaneous solution of all equations, a novel dual-time stepping approach in conjunction with an implicit Runge–Kutta three-stage scheme is proposed. The reliability of the proposed numerical algorithm is then examined for a 1D Stefan condensation problem and two condensing flows including single bubble and steam-jet condensation problems. Particularly, for the single bubble condensation test, the bubble characteristics at different time instants are evaluated both qualitatively and quantitatively. For the steam-jet condensation test, the capability for capturing the evolution of interface deformations under different thermal and hydrodynamic flow conditions is highlighted. Finally, the effects of subcooling degree and steam mass flow rate on heat and mass transfer characteristics are investigated and discussed.

Study the effect of welding pass number on the mechanical and metallurgical properties of Aluminum type Al 1050 H14 produced by friction stir welding

Friction Stir Welding (FSW) is a solid-state welding technique with non-fusible rotary welds. Heat is generated by the friction produced between the weld tool and the two opposite surfaces of the two welded parts and the tool works on mechanical mixing with the presence of heat, pressure, and heat generated, reaching approximately (80-90%) of the melting point of the metal to be welded. In this study, Al 1050 H14 aluminum with a thickness of (6mm) was used for the purpose of welding it by means of the friction stir welding process in a butt welding method to obtain similar welding joints. A set with a square stitching tool Made of alloy steel was used by using a milling machine, with fixed (rotational speed of 1008 rpm and linear velocity of 40mm / min), an inclination angle of (2o), and counterclockwise rotation. The efficiency of welded joints was evaluated through static mechanical tests. Tensile tests, microscopic hardness, and visual examination. The results for all welds showed that the mixing zone (NZ) consists of fine grains of equal axes compared to the base metal. When welding on one side and in one path, the microstructure of HAZ was similar to the base metal. TAMZ was a transition region between HAZ and NZ. As for welding on one side, with two paths and three paths, the structure turned into a fine crystalline structure. By increasing the number of paths per side, the welding efficiency of the welded sample increased as the best efficiency was from one side and three paths (76.215%). Through the results, the tensile strength increases with the increase in the number of paths, as the best tensile strength was obtained when conducting the welding process from one side and by three paths, which is (93.653 MPa). It is equivalent to 76.21% of the tensile strength of the base metal. The hardness value in the weld zone (NZ) is higher than the other two zones (HAZ, TMAZ) due to the occurrence of dynamic recrystallization, which results in very fine and equiaxial crystals, but the hardness value in the weld zone remains less than the hardness value of the base metal.

Combined therapy of far infrared radiation, heat and castor oil, an alternative remedy against Covid-19 infection: A perspective

COVID-19 virus causes mass death worldwide which is facing an unending battle that needs unconventional evidence in complementary and alternative medicine. This review aims to elucidate the possible health benefit of far infrared from Nuga Bed/Mat® along with its heat produced and the application of castor oil pack that has antiviral property in the management of coronavirus infection. Far infrared radiation from Nuga Bed/Mat® has low wavelength and is perceived as heat by the thermoreceptors of the human body. The presence of heat from the Nuga Bed/Mat® coming from the far infrared radiation gives sufficient health benefits including detoxification, pain relief, reduction of muscle tension, relaxation, improved circulation, boosting of the immune system and lowering of blood pressure. SARS-CoV-2 infection manifests inflammation of the vascular endothelium which prevents proper circulation of the blood and can further progress to blood clotting. Treatment with Far infrared radiation for 40 minutes to 2 hours causes the stimulation of HO-1 protein that induces anti-inflammatory activity on the vascular endothelium and other sites of inflammation. Hence, improved blood flow can be expected after an exposure with far infrared radiation. With the added castor oil, spread on the specific site which has a corresponding antiviral property, the possibility of alleviation from the symptoms associated with coronavirus infection can give a light of hope as an alternative remedy.

MHD Flow and Heat Transfer of Hybrid Nanofluid over an Exponentially Shrinking Surface with Heat Source/Sink

In nanotechnology research, nanofluid technology contributes many applications to engineering applications and industry, such as power generation, solar collection, heat exchangers for cooling, and many more. However, there are still a few constraints in terms of heat transfer enhancement, although nanofluid properties show the best heat transfer rate compared with conventional fluids. Thus, this study was conducted for the purpose of investigating the behaviors of flow and heat transfer of hybrid nanofluid with carbon nanotubes (CNTs) on a permeable exponentially shrinking surface, as well as investigating the effects of a magnetic field and heat source/sink. This study was conducted by developing a mathematical model, which was the Tiwari–Das model for momentum and energy equations, and then transforming the model’s partial differential equations (PDEs) to ordinary differential equations (ODEs) using a similarity solution. Next, these equations were solved numerically using the MATLAB bvp4c boundary value problem solver. The authors particularly explored these behaviors with a few variations. Based on the results obtained, it was found that dual solutions exist in a specific range of the shrinking case, λc<λ<−λ and that the critical point λc also exists in a range of −1.5 < λc < −1 with different parameters. For the heat source/sink effect, the Nusselt number was higher when heat sink case ε < 0, whereas it decreased when the heat source case ε > 0. Therefore, this study deduced that the heat transfer rate of hybrid nanofluid (CNTs/Cu–water) is better than regular nanofluid (CNT–water) and conventional fluid (water). The present study took into consideration the problem of MHD flow and heat transfer analysis of a hybrid nanofluid towards an exponentially shrinking surface with the presence of heat source/sink and thermal radiation effects. The authors show that dual solutions exist within a specific range of values due to the shrinking case. The current work is predicted to have numerous benefits in equivalent real-world systems.

Impact of heat on biological concentrations of toluene and acetone resulting from exposure by inhalation: A pilot study

Climatic conditions raise new concerns about the potential impact of heat on the absorption and kinetics of certain chemicals. The impact of 3 temperatures (21, 25 and 30 °C WBGT) on the toxicokinetics of toluene and acetone was therefore evaluated in five human subjects during controlled exposures in an inhalation chamber. Biological samples were collected and analyzed by GC–MS/MS. Increases between 4 and 85 % were observed for solvents concentrations in blood (30 vs 21 °C) while decreases in urine samples for acetone and o-cresol were measured at the end of the exposure period (4 h). Mean blood concentrations at 4 h are well correlated with temperature. Results suggest an increased absorption and/or a decreased elimination of volatile chemicals in the presence of heat. Higher increases of blood chemical concentrations were observed in heavier individuals. Further studies should include physiologically based toxicokinetic models to help in better understanding the mechanisms involved and their respective contribution.

Loss Factor Behavior of Thermally Aged Magnetorheological Elastomers.

Polymer composites have been widely used as damping materials in various applications due to the ability of reducing the vibrations. However, the environmental and surrounding thermal exposure towards polymer composites have affected their mechanical properties and lifecycle. Therefore, this paper presents the effect of material-temperature dependence on the loss factor and phase shift angle characteristics. Two types of unageing and aging silicone-rubber-based magnetorheological elastomer (SR-MRE) with different concentrations of carbonyl iron particles (CIPs), 30 and 60 wt%, are utilized in this study. The morphological, magnetic, and rheological properties related to the loss factor and phase shift angle are characterized using a low-vacuum scanning electron microscopy, and vibrating sample magnetometer and rheometer, respectively. The morphological analysis of SR-MRE consisting of 30 wt% CIPs revealed a smoother surface area when compared to 60 wt% CIPs after thermal aging due to the improvement of CIPs dispersion in the presence of heat. Nevertheless, the rheological analysis demonstrated inimitable rheological properties due to different in-rubber structures, shear deformation condition, as well as the influence of magnetic field. No significant changes of loss factor occurred at a low CIPs concentration, whilst the loss factor increased at a higher CIPs concentration. On that basis, it has been determined that the proposed changes of the polymer chain network due to the long-term temperature exposure of different concentrations of CIPs might explain the unique rheological properties of the unaged and aged SR-MRE.

Numerical simulation of lid driven flow in a curved corrugated porous cavity filled with CuO-water in the presence of heat generation/absorption

In this article, numerical simulation is performed for mixed convection lid-driven flow of CuO-water nanofluid enclosed in a curved corrugated. Cylindrical obstacles having three different constraints: (adiabatic, cold, and heated) at its surface are considered. Internal heat generation/absorption and uniform heat is provided at the vertical wall of the cavity. The bottom wall is insulated, and the curve surfaces are maintained with cold temperature. Mathematically equations are developed from physical problems and solved through Galerkin weighted residual method of FEM formulation. The effect of various Reynold number (Re), Darcy number (Da), solid volume fraction of nanoparticles (ϕ), heat generation/absorption coefficient (Q) and various cylindrical obstacle on velocity, Nusselt number, molecular movements and the flow structure has been studied. Nusselt number increases for high Darcy number due to the convection in lid cavity. For high Reynold number generally Nusselt numbers decrease or remain the same at the wall with an increase of nanoparticles in porous medium. There significant effect of heat sink coefficient on temperature profile and Nusselt number decreases with increasing of Q.

Analysis of energy separation inside a Ranque-Hilsch vortex tube using RANS based CFD

The primary aim of this study was to investigate the role of turbulent structure in energy separation inside Vortex Tube. The important flow features were identified using RANS based CFD. The flow was divided into two parts above and below the cross-over region which is the radial location where the axial velocity is zero i.e., the flows above and below this region are oppositely directed. The Reynolds stress analysis revealed the stresses to be maximum at the cross-over region. In addition, the reversing and expanding core flow was found to have a temperature drop greater than that computed assuming an isentropic expansion process. This was also confirmed in the Control Volume (CV) analysis of the energy in the core flow wherein the core flow at the outlet of the CV was found to have experienced an energy loss compared to when it entered the CV. This was then correlated with the assumed work and heat interactions across the control surface bounding the CV of the core flow. The energy difference in the core flow computed by the two methods were found to agree within an accuracy of 10 %, thus validating our assumptions regarding the presence of heat and work transfer between the core and annular flows. The analysis also revealed that the turbulent shear work to be the dominant mode of energy transfer between the core and annular flows, comprising about 80 % of the energy transfer, and remaining 20 % attributed to heat transfer.

Shape effect of nanoparticles on MHD nanofluid flow over a stretching sheet in the presence of heat source/sink with entropy generation

PurposeIn heat transfer, fluids and nanoparticles can provide new innovative technologies with potential to adapt the heat transfer fluid’s thermal properties through control over particle size, shape and others. This paper aims to examine the effects of spherical and non-spherical (cylinder, disk, platelets, etc.) shapes of silver (Ag) nanoparticles on heat transfer enhancement and inherent irreversibility in hydromagnetic water base nanoliquid flow over a convectively heated stretching sheet with heat generation/absorption.Design/methodology/approachApplying suitable similarity constraints, the model partial differential equations are transformed into a set of nonlinear ordinary differential equations. Solutions are obtained analytically via optimal homotopy asymptotic method (OHAM) and numerically via shooting technique coupled with the Runge-Kutta-Fehlberg (RK-F) method.FindingsThe impact of Ag nanoparticle’s shape along with other germane factors, such as Biot number, magnetic field, solid volume fraction and heat source/sink on velocity and thermal profiles, Nusselt number, skin friction coefficient, heat transfer enhancement, rate of entropy generation and irreversibility ratio, are scrutinized via graphical simulations and discussed. This study revealed that cylindrical shape Ag nanoparticles generate high entropy and fluid friction irreversibility, whereas disk shape Ag nanoparticles exhibit high transfer enhancement rate. Moreover, a boost in magnetic field intensity, volume-fraction parameter and Biot number enhances the thermal boundary layer thickness.Originality/valueThe main objective of this work is to examine the different Ag nanoparticles shape effects on the heat transfer enhancement and inherent irreversibility owing to hydromagnetic nanoliquid flow past a convectively heated stretching sheet with heat source/sink, which has not been yet studied. It is hope that this study will bridge the gap in the present literature and serve as impetus to scholars, engineers and industries for more exploration in this direction. The intrinsic nonlinearity of the model equations precludes its exact solution; hence, OHAM and shooting technique coupled with the RK-F method have been used to numerically tackle the problem. Pertinent results are discussed quantitatively and displayed graphically and in tabular form.

Mixed convective flow of Ag–H2O magnetic nanofluid over a curved surface with volumetric heat generation and temperature‐dependent viscosity

AbstractThe magnetic nanofluid flow over a curved surface in the presence of heat and mass mixed convection, volumetric heat generation, and higher‐order chemical reaction is studied in this study. The Maxwell Garnetts model of thermal conductivity and the Brinkman model of viscosity are used for working fluid. The numerical method is applied to assess the governing nonlinear equations of the developed model. The influence of parameters, such as buoyancy, chemical reaction, magnetic field, curvature, heat generation, and chemical reaction order are considered in the existing study. The surface diagram for Nusselt number, skin friction coefficient, and Sherwood number are revealed. From the outcomes, it can be noted that with an increase in buoyancy parameters and , the heat and mass transfer (HMT) functions declined. Moreover, the behavior of HMT is reversed when there is an escalation in the values of chemical reaction parameter . A comparison of this study with a previous study is conducted.

Nonlinear Wave Model for Transport Phenomena in Media with Non-local Effects

The purpose of the work is to establish and substantiate the prerequisites under which the modified Whitham equation can play the role of a transfer equation in physical-chemical systems and technological processes.The contribution of this work lie in the fact that the perturbed Whitham equation describing propagation of nonlinear waves in media with non-locality has been derived using the nonlinear relaxation function. It is shown that while deriving the equations of the Whitham type, the presence of the spatial non-locality of the medium can play a fundamental role. The paper also considers the issues of physical interpretation of the model under study. The principal presence of non-local effects in studied systems can be substantiated and obtained as a result of the presence of domains with a complexly organized spatial structure as well as in the presence of heat and mass sources. The new model submitted in the work can find application in methods for calculating the intensity of heat and mass transfer in complexly structured heterogeneous systems.

Irreversibility analysis of carbon nanotubes subject to rotating frame

This article interprets the chemically reactive flow of water-based carbon nanotubes subject to rotating frame. Homogeneous-heterogeneous reactions are considered. Heat transfer is studied in presence of heat generation/absorption and viscous dissipation. Flow in porous space is investigated through nonlinear Darcy-Forchheimer expression. Carbon nanotubes of two types (namely single wall SWCNTs and multi wall MWCNTs) are utilized. Optimal solutions are obtained through optimal homotopy analysis method (OHAM). Roles of sundry variables on flow fields, physical quantities and entropy generation rate are interpreted. It is witnessed that rate of entropy generation increases through homogeneous and heterogeneous reaction parameters.

Modification of Hand Molding Flower Vase for Thermo Plastic Recycling

Broadly speaking, plastics can be grouped into two groups, namely: thermoplast plastics and thermoset plastics. Thermoplast plastics are plastics that can be repeatedly printed in the presence of heat. Thermoplast plastics include: PE (Polyethilene), PP (Polypropylene), PS (Polystirene), ABS (Abutile Butadine Styrene), Nylon, PET (Polyethilene Terephthalete), POM (Polyacetal), PC (Polycarbonate) etc. Meanwhile, thermoset plastic is plastic which, if it has undergone certain conditions, cannot be reprinted because the polymer structure is in the form of a three-dimensional network. In making flower vases using hand molding tools, there are still shortcomings, such as during the melting process of plastic material, the heat given by the oil stove has not yet maximally spread the heat to the mold which causes the results to be not optimal. Besides, the heat given by the oil stove is not yet known by the operator. , because in the manufacture of flower vases have not used a controller to determine the temperature in the hand molding tool, the old mold results in the cylinder cannot be used for tensile testing. Therefore it is necessary to modify the hand molding tool. Based on the results of testing the tools that have been done, the following conclusions can be drawn: The product has a height of 16 cm, a thickness of 4 mm, a hand-molding tool can be a solution for reducing waste in the environment, plastic can be formed into a product that is valuable by processing it according to the temperature.

Application of Gyarmati’s principle to study active boundary layer control of ionic fluid past a Riga plate

Similarity solutions of laminar electromagnetohydrodynamic boundary layer flows in forced convection are investigated aiming at the evaluation of irreversible momentum, heat and mass transport balance equations by a variational principle. The transportation fields inside the boundary layer are approximated as trial polynomial functions, and the functionals of variational principle are formulated. The Euler–Lagrange equations of variational principle are constructed as algebraic equations in terms of momentum, thermal and concentration boundary layer thicknesses. Electrically conductive fluid flow over a semi-infinite flat plate controlled by electromagnetic force (Z) is considered. The effects of viscous dissipation (Ec), thermophoretic particle deposition (Nt) and thermal diffusion (Sr) in the presence of heat source/sink (Q) on skin friction, heat and mass transfer rates have been examined in this work. To demonstrate the efficiency of the present technique, some specific obtained results are compared with the known numerical results in literature and the accuracy is ensured. Further, the regression analysis is performed to state the dependency of these parameters on heat and mass transfer rates.

Determination of landfill gas generation potential from lignocellulose biomass contents of municipal solid waste

The presence of heat, methane (CH4) and oxygen in landfill sub-surface causes initiation of spontaneous waste ignition posing severe environmental impacts. A municipal solid waste (MSW) reactor (trough) was designed to monitor landfill gases (LFGs) i.e., CH4 and CO2 and its potential from different waste categories (synthetic waste, fresh waste, 3-month, 6-month, 3-year and 5-year-old waste) collected from open MSW dumpsite. The quantity of cellulose (C), hemicellulose (H) and lignin (L) contents (C + H: L) present in organic waste fraction of each waste category was determined. Results showed that fresh waste which has higher ratio of C + H: L is responsible for maximum CH4 and CO2 generation i.e., 31,660 and 46,078 ml/g of volatile solid, respectively. The ratio of C + H: L observed in fresh waste, 3-month, 6-month, 3-year and 5-year-old waste was 2.62, 1.70, 1.32, 1.21 and 1, respectively. The study also showed that LFG generation is directly proportional to lignocellulose biomass contents present in MSW. Artificial neural network (ANN) modelling was used for the cross validation of CH4 yield (valuable product) which showed ±4% error between experimental and predicted data.

Bioconvection in a porous square cavity containing gyrotactic microorganisms under the effects of heat generation/absorption

In this paper, the bioconvective nanofluid flow in a porous square cavity containing gyrotactic microorganisms in the presence of heat generation/absorption is investigated. The bioconvection flow in porous medium is formulated based on Darcy model of Boussinesq approximation. Galerkin finite elements method is employed to solve the governing equations. The numerical results are obtained and discussed the effect of parameters such as Rayleigh number Ra, bioconvection number Rayleigh number Rb, Peclet number Pe, Lewis number Le, Brownian motion Nb, Thermophoresis Nt, Schmidt number Sc, Prandtl number Pr, heat generation/absorption Q and buoyancy ratio Nr. Also, the average Sherwood number, average Nusselt number and average density number are discussed. The present solutions are validated with existing studies under limited cases. It is found that Peclet number and buoyancy ratio show a significant increasing effect on the streamlines, isotherms, isoconcentrations of nanoparticles and microorganisms. The heat generation/absorption reverses the patterns of the flow, temperature distribution and isoconcentrations of nanoparticles and microorganisms.

Recent Progress of Thermocatalytic and Photo/Thermocatalytic Oxidation for VOCs Purification over Manganese-based Oxide Catalysts.

Volatile organic compounds (VOCs) are one of the main sources of air pollution, which are of wide concern because of their toxicity and serious threat to the environment and human health. Catalytic oxidation has been proven to be a promising and effective technology for VOCs abatement in the presence of heat or light. As environmentally friendly and low-cost materials, manganese-based oxides are the most competitive and promising candidates for the catalytic degradation of VOCs in thermocatalysis or photo/thermocatalysis. This article summarizes the research and development on various manganese-based oxide catalysts, with emphasis on their thermocatalytic and photo/thermocatalytic purification of VOCs in recent years in detail. Single manganese oxides, manganese-based oxide composites, as well as improving strategies such as morphology regulation, heterojunction engineering, and surface decoration by metal doping or universal acid treatment are reviewed. Besides, manganese-based monoliths for practical VOCs abatementare also discussed. Meanwhile, relevant catalytic mechanisms are also summarized. Finally, the existing problems and prospect of manganese-based oxide catalysts for catalyzing combustion of VOCs are proposed.

Numerical study of energy transmission through copper-based nanofluid contained in a partially heated isosceles triangular cavity in the presence of heat source/sink

This study reports computational simulation of natural convective energy transport through copper-based nanofluid contained in partially heated isosceles triangular conduit in the presence of invariable magnetic field under the influence of energy source/sink. Inclined sides of the enclosure are retained cold and horizontal boundary is supposed thermally insulated. Heat source of a particular length is placed on the horizontal wall. Relations expressing the energy transport and fluid flow are first dealt by penalty scheme and then composed expressions are assembled through Galerkin approximation scheme. Pertinent physical parameters governing the flow are the solid volume increment of nanoparticles (0.0 < < 0.06), Hartmann number (0 < Ha < 100), Rayleigh number (105 < Ra < 108) and coefficient of heat source/sink (−10 < Q < 10). It has been noted through this investigation that in consequence of magnetic force, reduction in heat transport occurs. Conduction and convection regimes are dominant for small and large Rayleigh numbers respectively. Energy transport rate is found zero on corners of the cold inclined walls. Obtained computational results reveal that the flow pattern relies considerably on the concentration of nanoparticles, coefficient of energy source/sink, Rayleigh and Hartmann numbers. Computed solutions are expressed through plots of streamlines, isothermal lines, and rate of local and overall energy flow. The current results are also validated through graphical comparison with the existing literature.