Improved traditional brick kiln for community-scale charcoal production: Thermal performance, microstructural characteristics, and economic evaluation

• An improved dual-wall brick kiln was significantly enhanced thermal distribution, achieving consistent carbonization at 450-500 °C. • The Charcoal produced exhibited an average FI of 0.85 and a HUE of 36.33%. • Techno-economic analysis showed a net profit of 1,069.43 USD/year. This study presents the design, fabrication, and evaluation of an improved traditional brick kiln (improved large-scale charcoal kiln) optimized for community-based enterprises. The modified kiln, measuring 3.0 m long, 2.0 m wide, and 1.3 m high, features a dual-layer brick structure with a thermal insulation air gap and raised flooring integrated with horizontal airflow channels to promote uniform heat distribution. Cajuput wood was selected as the feedstock, with a moisture content (MC) of 17.7 ± 3.2% d.b., an average diameter of 0.10 ± 0.01 m, and a length of 1.14 ± 0.05 m, the system can accommodate 1,500-2,000 kg of wet wood per production cycle. Experimental assessments, including real-time temperature profiling, water boiling tests (WBT), scanning electron microscopy (SEM), average friability index (FI), thermogravimetric analysis (TGA), and economic evaluation, were conducted to evaluate the charcoal kiln system. The results showed that carbonization temperatures of 450-500°C, sustained over a 4-5 days operational period, produced charcoal with a low moisture content of 3.4% (d.b.) and a well-developed porous microstructure. The charcoal exhibited an average FI of 0.85 and a heat utilization efficiency (HUE) of 36.33%. Economic evaluation indicated an annual net profit of 1,069.43 USD, with each production cycle yielding approximately 33.96 USD. These findings affirm the kiln's viability as a sustainable, scalable solution for rural charcoal production, enhancing technical performance, product quality, and financial returns for local stakeholders.