Volume 5 Issue 1
Authors: M.Y. Abdollahzadeh Jamalabadi; Moein Rajabzadeh; P. Hooshmand
Abstract: The present manuscript is dedicated to the study of non-premixed combustion within a vertical cylinder filled by inert porous media using a turbulence model. A study of the effect of inlet gas angle on methane/air combustion is performed. Governing equations of Navier-Stokes, energy and the chemical species transport equations in a porous media with local thermal non-equilibrium assumption between the solid and fluid are solved. Distinct energy equations are considered for the porous burner and the fuel in it. Inlet velocity and excess air-to-fuel ratio are varied in order to analyze their effects on temperature, turbulent kinetic energy distribution and flame front location. The temperature field and species concentrations are presented in the premixed methane - air combustion. The results show that an increase in angle of inlet gas enhances the mixing rate, the peak temperature, and water and carbon dioxide volume fraction inside the middle region of the chamber. The locations of the maximum temperature and product concentration shift closer to the combustor inlet with an increase in inlet angle. Furthermore, the temperature in porous burners is lower than free flame burners, and lower NOx and CO pollutant are achieved.
Keywords: Methane/Air Flame; Turbulent Model; Numerical Simulations; Non-Premixed; Porous Media
Authors: T. O. Olugbade; T. I. Mohammed
Abstract: Rice bran is a biomass residue that is produced in large quantities in rice-growing regions of Nigeria. Although it is a good source of fuel and its rate of generation is enormous, this essential residue aggregates as waste at rice mills, rice fields, and other processing centers. This causes a disposal problem that leads to environmental pollution. There is also the problem of over-consumption and dependency on wood fuel as a source of energy. Rice bran briquettes serve as an alternative solution for the disposal problem and reduce the consumption and dependency on wood fuel. Three grades of cylindrical briquettes with centrally located holes were produced from a mixture of rice bran and palm kernel shells of different mixing ratios using cassava starch as a binder. The mixing ratio with highest heating value was determined. Cassava starch was found to be more suitable because it has a higher binding effect, burns effectively with less smoke, and it is cheap and readily available. The palm kernel shells were ground into three different particle sizes (2 mm, 4 mm, and 6 mm). The three sizes of ground palm kernel shells were mixed separately with rice bran, each in ratios of 1:9, 2:8, 3:7, 4:6, and 5:5 (palm kernel shell to rice bran). The briquettes were made using a manually operated machine with sixteen moulds at the optimum pressure of 3.5 N/mm2, which formed briquettes with a density of 524 kg/m2. The higher heating value of the briquettes was 14.25 MJ/kg. The calorific value increased with a decreasing palm kernel shell grain size, and the maximum calorific values were obtained in the 3:7 ratio (palm kernel shell to rice bran). The briquettes were produced with a ratio of 6:1, rice bran-palm kernel shell to starch.
Keywords: Binder; Biomass; Briquettes; Cassava Starch; Fuel; Heating Value; Palm Kernel Shell; Rice Bran