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In this article, we present a comprehensive analysis of the flow and heat transfer characteristics of a fully developed incompressible, electrically conducting, and radiatively active fluid flow in micro-channel in the presence of transverse magnetic field. The Navier-Stokes and energy governing equations for magnetohydrodynamic flow, including thermal radiation and rarefaction effects, are considered to examine the wall properties (friction and heat transfer) and the flow properties (temperature and velocity). Two rarefaction effects of velocity slip and temperature jump at the wall are modeled as the product of characteristic slip/jump length and the first derivatives of velocity and temperature, respectively. Since the natural convection of magnetohydrodynamic flow in channel is resulted from the competition between deriving forces by pressure gradient, temperature gradient, and magnetic field, its flow and heat transfer characteristics should be understood systematically. First, we obtain the system parameters representing thermal radiation, buoyancy, magnetic field, temperature difference, velocity slip length, and temperature jump length through the non-dimensionalization process, and then their influences are rigorously evaluated by solving the governing equations numerically using RungeKutta algorithm with shooting method.

This study presents the effect of thermal radiation on the steady flow in a vertical micro channel filled with highly absorbing medium. The governing equations (mass, momentum, and energy equation with Rosseland approximation and slip boundary condition) are solved analytically. The effects of thermal radiation parameter, the temperature parameter, Reynolds number, Grashof number, velocity slip length, and temperature jump on the velocity and temperature profiles, Nusselt number, and skin friction coefficient are investigated. Results show that the skin friction and the Nusselt number are increased with increase in Grashof number, velocity slip, and pressure gradient while temperature jump and Reynolds number have an adverse effect on them. Furthermore, a criterion for the flow unsteadiness based on the temperature parameter, thermal radiation parameter, and the temperature jump is presented.

Abstract:Investigation of the effect of thermal radiation on a fully developed magnetohydrodynamic (MHD) convective flow of a Newtonian, incompressible and electrically conducting fluid in a vertical microchannel bounded by two infinite vertical parallel plates with constant temperature walls through a lateral magnetic field of uniform strength is presented. The Rosseland model for the conduction radiation heat transfer in an absorbing medium and two plates with slip-flow and no-slip conditions are assumed. In addition, the induced magnetic field is neglected due to the assumption of a small magnetic Reynolds number. The non-dimensional governing equations are solved numerically using Runge-Kutta-Fehlberg method with a shooting technique. The channel is optimized based on the Second Law of Thermodynamics by changing various parameters such as the thermal radiation parameter, the temperature parameter, Hartmann number, Grashof to Reynolds ratio, velocity slip length, and temperature jump.

A new concept of low NOx burner, based on a partial oxidation combustion concept, is successfully applied in this research. The burner is designed such that a portion of liquid fuel is heated and pre-vaporized in the furnace then injected into a fuel rich combustion zone so that a partial oxidation reaction occurs. The effects of equivalence ratio, thermal load, and fuel distribution ratio on the emissions of NOx and CO are experimentally investigated. This newly developed burner showed very low NOx emission level, about 12 ppm, when light oil is used as a fuel.