Combustion characteristics of an annular type meso-scale combustor

This study was conducted to develop a meso-scale annular type combustor that uses two types of coaxial cylindrical flames, rich premixed flame and diffusion flame. The combustor consists of inner and outer porous tubes, and rich C3H8-air mixture and air issued, respectively, through the inner tube outwardly and through the outer tube inwardly, forms a cylindrical stagnation plane sandwiched by the inner rich premixed flame and the outer diffusion flame. A petal type flame was also observed in the downstream of the cylindrical flames. Maintaining a constant equivalence ratio phi(i), and flow rate q(i) of the rich mixture, the overall equivalence ratio phi(all) is controlled by varying the air flow rate q(o) of the outer tube. In order to investigate the combustion performance, the temperature was measured inside and at the outlet of the combustion chamber. The heat loss rate and exergy loss rate were evaluated from the obtained temperature data. The minimum values of the heat loss rate and exergy loss rate were 0.30 and 0.57, respectively. These loss rates were compared with the performance of other meso-scale combustors.