Effect of multihole baffle-induced lobe flow structures on a high efficiency micro-thermophotovoltaic system

Abstract

For a combustion-based thermophotovoltaic generator (TPV), the baffle-induced reacting flows are numerically investigated in the micro combustor with a multihole baffle representing a mixed feature of bluff body and multiple jets. The lobed flow feature is realized by the momentum difference between fuel and air streams and the baffle wall, not the geometrical conditions like a lobed nozzle. Compared with the H2–air combustor, the lobed flame and the votical structure are enhanced for the CH4–air combustor. To analyze the lobed structure, the lobe intensity and the equivalent perimeter are defined for the stoichiometric mixture line. The maximum lobe intensity is observed at the beginning zone of flame, whereas the equivalent perimeter is increased near the active reaction zone. As the baffle thickness decreases, the lobe structure is enhanced due to the increased vortices. Also, a close relationship between the maximum vorticities at the baffle exit and the maximized lobe structure is observed. The intensified lobe structure contributes to a shorter flame length and more efficient combustion, resulting in increased radiation available for a micro-TPV system. When the lobe structure is enhanced, the high emitter efficiency for an energy conversion device is obtained as 0.319–0.326 for the H2–air combustor.