Papers by Keyword: Radiation Heat Transfer

Abstract: The present research studies on the effect of nanoparticles on polymeric coatings and heat transfer in them. For this purpose, three different weight percentage of nanozirconium oxide (1, 3 and 5%) were added to polyurethane resin and applied on metallic plates. To determine the radiation heat transfer coefficients, emissivity coefficient and thermography of the samples along a region of long wavelengths (IR) were measured. The results showed that by adding zirconium oxide nanoparticles to the polyurethane resin, the absorption and emissivity coefficient of coating in all three samples were improved compared to the coating without nanoparticles.

Abstract: In order to obtain the radiation heat transfer theory and calculation methods, the movement of the gas particles, location, intensity, temperature, are researched in cylinder under different conditions with combustion system and the mode of heat transfer. Under high temperature conditions in the cylinder, the gas radiation heat transfer is researched in the complex heat transfer theory. A statistical correlation K narrow band model, a mean absorption coefficient, a gas line databases, by-line calculation method are found, through research and analysis emissivity, transmittance, absorption coefficient, typical models, mathematical equations, database, calculation methods. Examine the distribution performance of each database for different media concentration and temperature, a statistical narrow-band band parametric model accuracy is tested, using statistical narrow band model, the results of the use of by-line method. Research shows: selected spectral database, calculation method has a greater impact on the results. The research also shows the result coincides calculations based by-line HITEWP2010 database method, whether radiant heat or wall flux, statistical narrow band model. These are supplied to the internal combustion engine cylinder design.

Abstract: This paper studies the chemical combustion reaction of coke oven gas coupled with radiation heat transfer in the slab reheating furnace. Three dimensional temperature distributions of the produced gases and slabs in the combustion furnace are investigates numerically. Numerical results reveal that the radiation heat transfer dominates the heating process in the combustion furnace; it is around 95% of total input heating energy. The heating efficiency is examined for the sake of energy saving in the combustion furnace.

Abstract: This paper deals with heat transmission through porous material subjecting to high levels of radiation. In depth absorption of radiant energy would lead to increased in-depth temperature which would cause a thicker pyrolysis zone, that lead to uncontrolled material spallation and failure. Analytical treatments of such problems had been attempted by many researchers [, approaches vary from theoretical principles to engineering correlations, but unfortunately no appropriate temperature and pressure-dependent material properties are available which are needed for their estimations, and extensive experimental measurements would still be required for their evaluations. This paper describes an experimental system developed for direct measurement of radiation transport parameters which is developed with reference to the experimental setups of previous investigators.

Abstract: This paper deals with the numerical solution for radiative heat transfer within a heated six wall surfaces baking oven, baking tin surface and bread surface. The radiation heat transfer model is constructed by adopting a radiation network representation analysis. The analysis applies view factor and radiosity in determining the radiation rates for each surface in the oven. The amount of radiation heat, q and temperature, T variables are equivalent to electric current and voltage, respectively. Finite difference method coupled with Gauss-Seidel iteration was selected to solve the equations involved in the analysis. Even though this method is tedious and intractable for multiple surfaces, but it would seem to be the most accurate and suitable approach for radiation analysis in the enclosure.

Abstract: The flow in air-gap of turbo-generator was simplified to the rotating flow model in the 2D concentric cylinder annular space. According to the CFD principle, the rotating flow model equations of the laminar flow and the turbulent flow were solved with Finite Volume Method. After being compared with the analytical solution of the 2D concentric cylinder Couette shear flow, the 2D air-gap model, the boundary conditions and the calculation results were proved to be accurate. On the basis of the study of the velocity field, the energy equation and the radiation equation were added to study the temperature field in the annular space. The convection and the radiation heat transfer were considered under the first boundary conditions. The turbulent flow and temperature distribution of the annular space under the steady-state were analyzed

Abstract: A numerical simulation procedure for studying deposition of aerosol particles in a laminar convection flow of radiating gas over a backward-facing step including the effect of thermal force is developed. In the gas flow, all of the heat transfer mechanisms consisting of conduction, convection and radiation take place simultaneously. Behavior of solid particles is studied numerically based on an Eulerian–Lagrangian method. Two dimensional Navier-Stokes and energy equations are solved using CFD techniques, while the radiating transfer equation (RTE) is solved by discrete ordinate method (DOM) for calculating radiative heat flux distribution. The objective of this research is to study the effect of Reynolds number variation and also radiation on thermophoretic deposition of particles. Numerical results show a decrease in deposition percent by increasing in Reynolds number and the radiation effect is negligible. The results are compared with the existing experimental and numerical data and good agreement is found.

Abstract: Providing a suitable thermal condition for the paint to be cured is of important parameters in achieving a desired cure. Continuous radiation ovens are of widely used apparatuses in paint cure and coating industries. Designing of these ovens for curing bodies of complex geometries have become a challenge for many years. In the present study a designing method is introduced and advised because of its acceptable capabilities. This method is based on cure window criterion and applies gradient optimization technique. The time consumed for designing is tried to be decreased through this model. A significant part of the time of designing procedure usually devotes to calculation of the physical model and to the iterations of optimization procedure. In this regard, defining a proper objective function efficiently reduces the designing time. Procedure of finding an appropriate objective function has been comprehensively discussed in the present article. Capability of the proposed methods is then evaluated for a simple two dimensional geometry of an automobile.

Abstract: The objective of this research was to develop methods for improved the uniformity of temperature distribution within plasma surface alloying furnace by simulating the heat transfer process and numerical calculation. Results show that the structure of charging basket, hanging auxiliary cathode plates in both sides of charging basket and blackness of material influence strongly temperature distribution within the plasma surface alloying furnace. Discharge intensity of the center zone can be weakened through increasing the distance between backs both column blades in center of the furnace, which decreased the consumption of discharge power in center, depressed temperature of the center zone of the furnace. Intensity of discharge in fringe of the charging basket can be reinforced and that of discharge in center can be weakened when auxiliary cathode plates were hanged to outer flank of the charging basket, which increased boundary temperature of the system, at the same time the auxiliary cathode plate plays a heat preservation role. Decreasing the blackness of outside material of charging basket may decrease heat dissipating capacity of outside, decrease temperature difference of outside and center of the furnace and improve the uniform of temperature distribution in the furnace.