Numerical investigation of thermal performance of hydrogen fueled micro-combustor with trapezoidal ribs

Abstract

This paper presents a new micro combustor design based on four trapezoidal ribs equidistant distributed on its inner wall. The aim is to highlight its promising thermal performance improvements, using numerical simulations as a tool of investigation, compared to other micro combustors. The achieved improvement reflected the favorable effect of the trapezoidal ribs through quantitative computation of mean temperature, temperature difference, and standard deviation. The hydrodynamic study shows that the ribs shape and height elongate the equidistant distributed recirculation zones, resulting in a significant increase in the flow residence time. Furthermore, the outer wall temperature level increases significantly from 1371.25 K to 1417.71 K and the non-uniformity zone is reduced compared to the simple backward facing step micro combustor. A better understanding of the mechanisms involved in heat transfer and their respective contributions to the overall thermal performance of the different micro combustors are explicitly analyzed. Moreover, the results highlight the favorable effect of the inlet velocity of 10 m/s to obtain the optimal outer wall temperature level and uniformity. The rich mixture composition provides the closest thermal performance to the stochiometric case, which widens the operating range for MTPV systems and improves their efficiency and reliability.