Performance assessment of ringed and non ringed inclined tubes for natural convection in eco efficient stoves

Abstract Purpose The study aims to develop and evaluate a naturally draft driven smokeless biomass stove. Air is supplied through inclined tubes mounted along the stove wall. Plain and ringed inclined tubes were tested to measure tube air temperature and assess airflow characteristics. Results show that the inclined tube with internal rings attains higher air temperature inside the tube as compared to a plain tube, thereby enhancing buoyancy driven airflow from surroundings into the combustion chamber. Design/Methodology/Approach A triple chamber smokeless stove was experimentally tested using plain and ringed inclined tubes. The ringed tube consists of internal square section rings. Five K‐type thermocouples measured temperature along each tube. Air flow into the combustion chamber was calculated based on pressure difference generated by buoyancy. A buoyant flow model validated the data and assessed draft behavior. Findings The ringed tube exhibited wall temperatures 8–18°C higher than the plain tube, with a maximum of 197°C compared to 182°C for the plain configuration, indicating improved heat transfer. This rise in wall temperature led to increased buoyancy driven airflow, about 10.9% higher airflow than the plain tube. This improvement is attributed to the controlled turbulence generated by the internal rings, which strengthens air mixing and promotes efficient natural convection. Statement of Industrial Relevance The proposed design is highly relevant for rural and off grid applications. It aligns with sustainable development goals by promoting clean cooking technologies. Novelty or Significance This study presents a passive draft enhancement approach by incorporating internal square section rings. The arrangement significantly improves airflow and combustion performance without requiring any external power. The rings enhance buoyancy driven airflow, establishing a simple economical and energy independent method to improve stove performance through controlled turbulence.