Numerical Investigation of the Combustion in an Improved Microcombustion Chamber with Rib

Abstract

This study proposes an improved microcombustor with a rectangular rib to improve the temperature level of the combustor wall. Moreover, the OH mass fraction, temperature distribution, and outer wall temperature of the original and improved combustors of premixed hydrogen/air flames are numerically investigated under various inlet velocities and equivalence ratios. Results show that the improved microcombustor enhances heat transfer between the mixture and wall because its recirculation zone is larger than that of the original, thereby resulting in high wall temperature. Conversely, thermal resistance in the horizontal direction increases with upstream and downstream step lengths. Consequently, the outer wall temperature decreases with step length in the improved combustor. A high equivalence ratio (e.g., 0.6) may result in the destruction of the combustor because the wall temperature has exceeded the acceptable temperature of wall material quartz. Therefore, the improved microcombustor is recommended for micro-thermo-photovoltaic systems.

Performance Evaluation of H2/Air Premixed Combustion in a Suddenly Expanded Microcombustor with Wall Fin

“…Impact ranking from the largest to the smallest is hydrogen/ air equivalence ratio, inlet velocity, and inlet temperature Chen et al (2019) [19] Ribbed cavity planar (2D) Inlet velocity, equivalence ratio H 2 /13 species 19 reactions OH mass fraction, temperature distribution, outer wall temperature Improved temperature level and flame stability due to rib Peng (2019) [39] Two rearward-step tube (3D) Backward-facing steps and inlet shapes 2018) [23] Convergent-divergent tube (3D) Throat diameter and location H 2 /9 species 19 reactions…”

“…Yang et al [18] used backward-facing step in microcombustors for MTPV systems and proved that the step can help in flame stabilization under higher inlet velocities and a wide range of equivalence ratios. Several design features such as cavities in microcombustor walls along with bluff bodies, [5] rectangular ribs, [19,20] and doublecavity configurations [21] have been proposed for the purpose of performance enhancement. Convergent-divergent [22,23] and wavy wall [2] configurations have been also explored and found to influence combustor efficiencies.…”

Design and performance analysis of hydrogen-fueled micro combustion chamber with focus on back pressure minimization

“…Moreover, when the combustion chamber size is reduced, the mixture's residence time decreases due to incomplete combustion occurring in the chamber. In a Planar micro combustor, cavities are included to minimize the issues [18][19][20][21][22] .…”

Numerical Investigation of Effect of Structural Parameters on the Performance of a Combustion-Driven Sparkjet Actuator

“…However, the jet velocity of the combustion driver needs fur hancement. Based on small-scale combustion technology [19][20][21][22][23][24], Crittenden [25] proposed a new actuator powered by combustion. Figure 2 shows the schematic of the micro axisymmetric combustion driver.…”

“…Narayanaswamy V et al [18] conducted an experimental study of a pulsed-plasma jet actuator's performance and found that the pulsed-plasma jet actuator creates a sufficiently strong flow perturbation that holds great promise as a supersonic flow actuator. Based on small-scale combustion technology [19][20][21][22][23][24], Crittenden [25] proposed a new actuator powered by combustion. Figure 2 shows the schematic of the micro axisymmetric combustion driver.…”