Understanding key parameters enhancing performance of iron powder combustion in a semi-practical burner

• Demonstrates stable, self-sustaining iron powder combustion using a semi-practical burner without external heat support at preheating temperatures ≥760 °C. • Identifies optimal operational parameters, including swirl number, power output, and humidity conditions, for maximizing combustion efficiency and oxidation degree. • Swirling flow significantly enhances combustion stability, promoting iron flame formation, increasing residence time, and reducing unburned iron particles. • High combustion efficiency and low NO emissions are achieved across varying power outputs, supporting iron powder’s potential as a clean energy carrier. • Water vapor content affects ignition and NO emissions, with higher humidity suppressing combustion performance, especially under fuel-lean conditions. This work investigates the combustion of micron-sized iron powder as an energy storage medium using the semi-practical Metal Cyclonic Combustor (MC 2 ). It evaluates the effects of preheating temperature, power output, water vapor content, and swirling flow on flame characteristics, combustion efficiency, gas temperature, residue composition, and NO emissions. A preheating temperature of 760°C yields an oxidation degree of 90 wt% without external heat support, although the flame is non-stationary. At 810°C, the flame becomes stationary and more stable, with higher oxidation degree and gas temperature. Increasing the iron powder injection rate enhances power output and gas temperature but requires burner modifications for sustained efficiency. Water vapor decreases the degree of oxidation, increases the amount of unburned iron, and lowers particle and gas temperatures, while contributing to NO formation. However, excessive vapor reduces NO emissions by absorbing heat and lowering the gas temperature. Swirling flow improves combustion efficiency, stabilizes the flame, and reduces unburned iron. Under fuel-lean conditions, it facilitates the transition to a stationary self-sustaining flame. These findings support the feasibility of iron powder as an efficient energy carrier and advance iron-based combustion technology for sustainable energy systems. This work investigates the combustion behavior of micron-sized iron powder using a semi-practical burner, focusing on its potential as a clean energy carrier. It analyzes iron flame characteristics, combustion residue composition, oxidation, efficiency, particle and gas temperatures, and NO emissions under varying conditions. Unlike previous single-particle combustion works, this work explores continuous combustion at a larger scale, identifying key parameters for stable, self-sustaining iron flames without heat support. The findings provide practical methods to enhance flame stability in real-world conditions, supporting iron powder as an efficient, clean energy system.