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Content available remote Modelling of heat transfer in a packed bed column
The CFD modelling of heat transfer in the packed bed column in the laminar and turbulent flow regimes has been presented. Three numerical grids with different densities were generated for the packed bed column. The modelling was performed with the use of the Porous Media Model for treating the flow inside a porous structure. The standard k-ε model along with the logarithmic wall functions for the turbulent flow range was used. The influence of the mesh size on the accuracy of the fluid flow was studied. Both radial and axial direction temperature distributions have been compared with the experimental data1 and the values calculated from a 2DADPF model. A good agreement between the experimental and the predicted values of the pressure drop, temperature distributions and heat transfer coefficient was obtained.
A systematic arrangement has been gotten for the transient issue of three-dimensional multilayer heat conduction in a circle with layers in the spiral course. The arrangement strategy can be connected to an empty circle or a strong circle made out of a few layers of different materials. By and large, the partition of factors connected to 3D round directions has interesting attributes because of the nearness of related Legendre works as the eigenfunctions. Additionally, an eigenvalue issues the azimuthal way likewise requires arrangement; once more, its properties are one of a kind inferable from periodicity the azimuthal way. In this way, broadening existing arrangements in 2D round directions to 3D circular directions isn't clear. In a round facilitate framework, one can explain a 3D transient multilayer heat conduction issue without the nearness of fanciful eigenvalues. A 2D tube shaped polar facilitate framework is the main other case in which such multidimensional issues can be tackled without the utilization of nonexistent eigenvalues. The nonappearance of nonexistent eigenvalues renders the arrangement philosophy fundamentally increasingly valuable for pragmatic applications. The strategy portrayed can be utilized for all the three kinds of limit conditions in the external and inward surfaces of the circle. The arrangement method is shown on an illustrative issue for which results are gotten.
This paper deals with the effects of heat transfer on unsteady MHD boundary layer flow of a chemically reading fluid past a vertical plate in the presence of thermal radiation and viscous dissipation. The governing equations of the problem under investigation are systems of partial differential equations. These equations are namely: continuity equation, linear momentum equation and energy equation. These systems of equations were non-dimentionalized by introducing non-dimensional variables. We resulted to dimensionless systems of partial differential equations. The fluid considered in this paper are optically thick, however we employ the Roseland model. Simulations were done numerically on all controlling parameters and the results generated were displayed in graphs and tables. Results review that thermal Grashof number intensifies the velocity profile and increase in Prandtl number leads to decrease in both the velocity and temperature field. Increasing thermal radiation intensifies the velocity and temperature profile. Thermal radiation speeds up the convection flow and thermal boundary layer of the fluid. Increase in magnetic parameter reduces the velocity profile as a result of the applied transverse magnetic field.
The isochoric thermal conductivity of an orientationally-disordered phase of CCl4 is analysed within a model in which heat is transferred by phonons and above the phonon mobility edge by ”diffusive” modes migrating randomly from site to site. The mobility edge ω0 is found from the condition that the phonon mean-free path cannot become smaller than half the phonon wavelength. The contributions of phonon-phonon, one-, and two-phonon scattering to the total thermal resistance of solid CCl4 are calcualted under the assumption that the different scattering mechanisms contribute additively. An increase in the isochoric thermal conductivity with temperature is explained by suppression of phonon scattering at rotational excitations due to a decrease in correlation in the rotation of neighbouring molecules.
In this paper, a new method for enhancing the pool boiling heat transfer coefficient of pure liquid, based on the gas injection through the liquids has been introduced. Hence, the effect of gas dissolved in a stagnant liquid on pool boiling heat transfer coefficient, nucleation site density, and bubble departure diameter has experimentally been investigated for different mole fractions of SO2 and various heat fluxes up to 114 kW/ m2. The presence of SO2 in captured vapor inside the bubbles, particularly around the heat transfer surface increases the pool boiling heat transfer coefficient. The available predicted correlations are unable to obtain the reasonable values for pool boiling heat transfer coefficient in this particular case. Therefore, to predict the pool boiling heat transfer coefficient accurately, a new modified correlation based on Stephan-Körner relation has been proposed. Also, during the experiments, it is found that nucleation site density is a strictly exponential function of heat flux. Accordingly, a new correlation has been obtained to predict the nucleation site density. The major application of the nucleation site density is in the estimating of mean bubble diameters as well as local agitation due to the rate of bubble frequency.
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