Simultaneous temperature and particle size measurement of burning iron particles using a single color camera

Abstract

Iron powder is recognized as a promising clean energy carrier and a recyclable metal fuel due to its high energy density and carbon-free nature. Research focusing on single iron particles is essential for understanding the combustion characteristics and mechanisms of iron powder, as well as for designing reliable iron-fuelled combustors. Temperature and particle size, as key parameters of burning iron particles, are typically measured using optical diagnostic methods. However, low-cost simultaneous measurement methods for the temperature and particle size of burning iron particles are scarce. This study introduces a method employing a single RGB camera to simultaneously measure the temperature and particle size of burning iron particles, validated by a heated thermocouple. Particle size is measured by the intensity of Blue channel based on light attenuation approach, and temperature is measured by the intensity ratio of Red/Green channels based on black-body radiation law. Statistical analyses of the temperature and particle size of iron particles at four different heights above the burner were conducted. Along the heights, the average particle size and temperature of the iron particles generally increase, except at a height of 50 mm, where more iron particles entering the cooling phase lead to a slight decrease in average temperature. The conditional probability density functions of temperature and particle size indicate a statistical dependence between the particle size and temperature of iron particles that larger particle sizes typically correspond to higher temperatures. The results confirm that the simultaneous measurement method is a cost-effective, high-accuracy tool for characterizing the combustion behavior of iron particles.