Abstract

Brick manufacturing in Nepal relies heavily on coal and biomass mixtures, resulting in high energy use and significant air pollution. This study investigates the energy-saving potential and environmental implications of fuel substitution in brick kilns, focusing on coal, biomass, and natural gas. A combination of experimental data collection and steady-state computational fluid dynamics simulations was employed to analyse thermal performance, airflow characteristics, and pollutant formation along the kiln. The study evaluated the effect of varying inlet air velocities on fuel combustion, excess air, and kiln efficiency. For coal and biomass, inlet air velocities ranging from 4.5 to 6.1 m/s were analysed, while natural gas was studied as an alternative fuel for coal and biomass mixture under optimum condition. The results revealed that excess air in the combustion zone significantly influences the thermal efficiency, with coal and biomass showing higher excess air levels compared to natural gas. The kiln efficiency was determined using both direct and indirect method highlighting the potential for energy savings and emission reduction through optimized air supply and fuel transition. The findings provide quantitative insights into the benefits of energy transition in brick industries, demonstrating that adopting cleaner fuels and controlling excess air can improve efficiency and reduce environmental impact.