A sustainable biomass cookstove with helical heat exchanger and multi‐point steam injection under natural draft: Design and performance evaluation

Abstract This study aims to design and evaluate a sustainable biomass‐fired stove incorporating helical heat exchange, natural draft, and steam‐assisted combustion to enhance thermal efficiency, improve combustion quality, and promote a cleaner indoor environment. An advanced natural draft biomass stove was developed using a three cylinder configuration with insulated layers to minimize heat loss. A helical coil tube integrated within the combustion chamber facilitates efficient heat recovery for water heating. The system includes a connected water tank and superheater for continuous steam generation, which is injected through a multi‐point nozzle arrangement into the combustion zone. Inclined ringed tubes mounted along the chamber walls enhance natural convection, turbulence, and heat transfer, eliminating the need for forced draft systems. Experimental evaluation was conducted to assess thermal performance and combustion characteristics. The developed system achieved an overall thermal efficiency of approximately 49%, significantly higher than a conventional stove (approximately 17%). Carbon monoxide (CO) emissions were reduced in the range of 13.9 to 14.8 ppm, compared to about 720 ppm in traditional stoves. Formaldehyde (HCHO) emissions were also lowered in the range of 0.19 to 0.23 mg/m 3 from 0.85 mg/m 3 . The measured TPM emissions were found to vary between 128.9 and 136.2 mg/MJ, with an average value of 131.8 mg/MJ, indicating comparatively cleaner combustion behavior of the developed biomass stove system. The system produced superheated steam at a rate of 0.00423 kg/s within 5–7 min, contributing to improved combustion through enhanced turbulence and mixing. A stable combustion zone temperature of approximately 640°C was achieved under natural draft operating conditions, indicating effective combustion and heat recovery performance.