M.Z. Abu Bakar

Combustion in porous media and its applications – A comprehensive survey

The rapid advances in technology and improved living standard of the society necessitate abundant use of fossil fuels which poses two major challenges to any nation. One is fast depletion of fossil fuel resources; the other is environmental pollution. The porous medium combustion (PMC) has proved to be one of the technically and economically feasible options to tackle the aforesaid problems to a remarkable extent. PMC has interesting advantages compared with free flame combustion due to the higher burning rates, the increased power dynamic range, the extension of the lean flammability limits, and the low emissions of pollutants. This article provides a comprehensive picture of the global scenario of research and developments in PMC and its applications that enable a researcher to decide the direction of further investigation. The works published so far in this area are reviewed, classified according to their objectives and presented in an organized manner with general conclusions. A separate section is devoted for the numerical modeling of PMC.

Integrated CFD simulation of concentration polarization in narrow membrane channel

Numerous analyses on the mass transfer phenomena and hydrodynamics for the fluid adjacent to the membrane have been studied and visualized by computational fluid dynamics (CFD) mathematical modeling and simulation. The availability of CFD simulation study to reveal the concentration polarization profile in the membrane channel, which considering hydrodynamics and membrane transport properties is found to be limited. The main goal of this paper is targeted to the utilization of CFD simulation using commercial CFD package FLUENT to predict the concentration polarization profile, mass transfer coefficient and wall shear stress under different types of conditions in the empty narrow membrane channel. The permeation conditions such as permeation flux and mass fraction have been taken into account in the solution of the governing equations. Simulation results show that the concentration polarization phenomena can be reduced by increasing feed Reynolds number. The decrease of wall shear stress also contributes to the formation of the concentration polarization layer along the membrane surface. The simulated results were validated and compared with the literature data, showing a satisfactory agreement.

Effect of heater geometry on the high temperature distribution on a MEMS micro-hotplate

Temperature uniformity on a micro-hotplate is important for gas sensor sensitivity, linearity, and resolution. There are several ways to create a uniform temperature distribution on a micro-hotplate. In this paper, the modification of microheater geometry is the method used. Four different heater geometries are simulated using ConvetorWare software to determine which geometry can give the most uniform temperature distribution. The simulations show that the heater geometry which combines parallel and meander shapes results in the most uniform heat distribution. The electrical potential and current distributions of the four different micro-heater geometries are also evaluated.

The Development and Performance Analysis of Partially Premixed LPG Porous Medium Combustor

Abstract Porous medium combustion has interesting advantages compared with free flame combustion due to higher burning rates, an increased power dynamic range, extension of the lean flammability limits, and low emissions of pollutants. This article presents the development and testing of a partially premixed porous medium combustor with liquified petroleum gas as fuel. The discrete porous medium is made up of Al2O3 spheres, the size of which is optimized by computer simulation. The NOx and CO emissions are measured for different numbers of porous layers and for different sizes of ceramic spheres, under both steady state and transient conditions of combustion. The data so obtained are plotted and compared with that of free flame combustion. The results show that the burner has good combustion efficiency and significantly lower NOx and CO emissions compared to the conventional combustor.