v38n2a05 - Latin American Applied Research 38:129-140(2008...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Latin American Applied Research 38:129-140 (2008) 129 ANALYSIS OF HEAT AND MASS TRANSFER IN A MIXED CONVECTIVE DIFFUSION FLAME ATTACHED TO A VERTICAL FUEL SURFACE A. J. BULA and M. M. RAHMAN Departamento de Ingeniería Mecánica, Universidad del Norte, Kilómetro 5 Antigua Vía Puerto Colombia, Ba- rranquilla, Colombia. [email protected] Mechanical Engineering Department, University of South Florida, 4202 E Fowler Av, Tampa, FL, 33620, USA [email protected] Abstract −− Analysis of heat and mass transfer in a burning vertical surface exposed to a fluid flow parallel to the surface is presented. The combustion process considered is steady and the burning surface is in equilibrium vaporization. A fast gas phase reac- tion is assumed to occur between the fuel and the oxidizer. The flame sheet approximation is used to describe the reacting flow. The governing equations describing the conservation of mass, momentum, energy, and species concentrations were solved nu- merically along with appropriate boundary condi- tions. Schvab-Zeldovich variables were used to eliminate the mass and energy generation terms from the governing equations. Calculations were done for two different fuels and for a range of Rey- nolds number. Computed results included the distri- butions of velocity components, enthalpy, and con- centration of fuel, oxidizer, products, and inert gas, and the position of the flame sheet. Keywords Diffusion flame, conjugate heat transfer, heat and mass transfer. I. INTRODUCTION Diffusion flames are observed during the combustion of a solid, liquid, or gaseous fuel. Some common exam- ples include fires, furnaces, and burners. Many of these combustion processes occur under the combined influ- ence of a vertical buoyant flow and an external forced flow. The analysis of such a mixed convective flow is the objective of the present investigation. The laminar natural convective burning of a vertical fuel surface was first addressed by Spalding (1954). After making several simplifying assumptions, a simi- larity solution was obtained for the boundary layer flow on a flat surface. Williams (1985) introduced a mathe- matical transformation, known as the Schvab-Zeldovich transformation, to simplify the governing equations. Shih and Pagni (1978) described a laminar, free and forced, mixed-mode diffusion flame adjacent to a verti- cally burning fuel slab using Schvab-Zeldovich vari- ables, boundary layer and local similarity approxima- tions. The solution presented flame position, concentra- tions, velocity profiles and surface fluxes, and showed that the flow characteristics were more complicated than superposition of two limiting flame cases. Kinoshita and Pagni (1980) performed a numerical analysis of a steady, laminar, two-dimensional, non-radiative bound- ary layer. Based on the results, explicit functional fits to numerical flame heights were obtained for free and mixed-mode flows. The comparison with theoretical results indicated quantitative agreement. Liu et al.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/05/2011 for the course CSU 3 taught by Professor Handsome during the Spring '10 term at CSU Pueblo.

Page1 / 12

v38n2a05 - Latin American Applied Research 38:129-140(2008...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online