Effect of Participating Medium Radiation and Nano-Fluidic Behaviour of Atmospheric Aerosol on Natural Convection of Industrial Dusty Air

2013 ◽  
Author(s):  
Sofen K. Jena ◽  
Swarup K. Mahapatra
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Behavior ◽  
Carbon Black Particle ◽  
Laboratory Model ◽  
Heat Transfer Characteristics ◽  
Participating Media ◽  
Transfer Characteristics ◽  
Flow Circulation ◽  
Marker And Cell Method

The current study is focused on thermal radiation interaction with the natural convection of atmospheric brown cloud (ABC). The current study puts emphasis on ultra fine carbon-black particle suspension of several nano meter range along with some pollutant gas mixture with atmospheric air. The numerical simulation of double diffusive thermo-gravitational convection of ABC is done with Hide and Mason laboratory model for atmosphere. The effect of flow circulation is simulated by setting different value of buoyancy ratios. The effect of participating media radiation has been investigated for various values of optical depth. The governing equations, describing circulation of ABC are solved using modified Marker and Cell method. Gradient dependent consistent hybrid upwind scheme of second order is used for discretization of the convective terms. Discrete ordinate method, with S8 approximation is used to solve radiative transport equation. Comprehensive studies on controlling parameters that affect the flow and heat transfer characteristics have been addressed. The results are provided in graphical and tabular form to delineate the flow behavior and heat transfer characteristics.

The Effect of Temperature Dependent Electrical Conductivity on the MHD Natural Convection of Al2O3–Water Nanofluid in a Rectangular Enclosure

2014 ◽  
Author(s):  
Ali Mohammad Asadian ◽  
Omid Abouali ◽  
Mahmoud Yaghoubi ◽  
Goodarz Ahmadi
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Electrical Conductivity ◽  
Natural Convection ◽  
Effect Of Temperature ◽  
Fluid Viscosity ◽  
Heat Transfer Characteristics ◽  
Volume Fractions ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

The present paper is concerned with the study of flow and heat transfer characteristics in the steady state free convective flow of Al2O3-waternanofluids in a square enclosure in the presence of magnetic field. Attention is given to the temperature variation of the electrical conductivity and its effect on the electromagnetic force induced by the motion of the nanofluid. A new experimental correlation recently presented in the literature was used for this aim. In all the earlier studies in this area the electrical conductivity variation of nanofluid with temperature was neglected. The fluid viscosity and thermal conductivity are assumed to vary as a function of temperature and this variation is modeled using the available experimental correlations. The governing differential equations are solved numerically using finite element method. The features of fluid flow and heat transfer characteristics are analyzed for various strengths of the magnetic field and different nanoparticle volume fractions. The results show that when the inclusion of the variation of the electrical conductivity with temperature in the numerical model noticeably affects the natural convection heat transfer in the studied rectangular cavity. The variations of Nusselt number for natural convection of Al2O3-water nanofluid with nanoparticle volume fractions are presented at various Rayleigh and Hartmann numbers.

Natural Convection Heat Transfer Phenomena in Packed Bed Systems

2014 ◽  
Author(s):  
Olugbenga O. Noah ◽  
Johan F. Slabber ◽  
Josua P. Meyer
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Thermal Energy ◽  
Unit Volume ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Heat Transfer Characteristics ◽  
Coated Particles ◽  
Transfer Characteristics

Natural convection heat transfer in fluid-saturated porous media has in recent years gained considerable attention especially in High Temperature Reactors (HTR). It is lately proposed that Light Water Reactors (LWT) can be made safer by re-designing the fuel in the fuel assembly. In the proposed design, porous medium containing fuel in the form of loose coated particles in a Helium environment is introduced inside the cladding tubes of the fuel elements. These coated particles are treated as a bed from where heat is transferred to the cladding tube and the gas movement is due to natural convection. This proposal will require an understanding of the heat transfer characteristics from heated particles fuel to the gas atmosphere within the cladding tubes. In this present study, the natural convection heat transfer characteristics in packed beds from fluid-to-particle and bed particles to helium gas (thermal energy storage system) was experimentally investigated. Medium condition in this study was homogenous, isotropic, negligible radiant heat transfer and at local thermal non-equilibrium (LTNE). Theoretical formulation of microscopic thermal energy balance in the medium was employed in the analysis of experimental data. This formulation accounts for the convective heat transfer coefficient, the net rate of heat conduction into a unit volume of the solid and the heat production per unit volume of the particle. Dimensionless parameters like the Nusselt, Grashof, Prandtl, Rayleigh and Biot numbers defining heat transfer effect in the medium were equally determined and results validated with the KTA correlation.

Experimental Investigation of the Air Flow Behavior and Heat Transfer Characteristics in Microchannels With Different Channel Lengths

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Zhi Tao ◽  
Zhibing Zhu ◽  
Haiwang Li
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Critical Reynolds Number ◽  
Flow Behavior ◽  
Channel Length ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Poiseuille Number ◽  
Channel Lengths

This paper attempts to experimentally investigate the influence of channel length on the flow behavior and heat transfer characteristics in circular microchannels. The diameters of the channels were 0.4 mm and the length of them were 5 mm, 10 mm, 15 mm, and 20 mm, respectively. All experiments were performed with air and completed with Reynolds number in the range of 300–2700. Results of the experiments show that the length of microchannels has remarkable effects on the performance of flow behavior and heat transfer characteristics. Both the friction factor and Poiseuille number drop with the increase of channel length, and the experimental values are higher than the theoretical ones. Moreover, the channel length does not influence the value of critical Reynolds number. Nusselt number decrease as the increase of channel length. Larger Nusselt numbers are obtained in shorter channels. The results also indicate that in all cases, the friction factor decreases and the Poiseuille number increases with the increase of the Reynolds number. It is also observed that the value of critical Reynolds number is between 1500 and 1700 in this paper, which is lower than the value of theoretical critical Reynolds number of 2300.

Sign in / Sign up

Export Citation Format

Share Document