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.
Highlights
Micro-electro-mechanical system (MEMS) technology has received considerable attention in recent years [1,2,3]
A micro-thermophotovoltaic (TPV) system geometry consists of photovoltaic cells, emitter, filter, and heat source (Figure 1)
Peng et al [12] numerically examined the thermal performance of a microcombustion chamber with and without a front cavity and found that the front cavity enhances the stability of the microcombustor
Summary
Micro-electro-mechanical system (MEMS) technology has received considerable attention in recent years [1,2,3]. Us, micro-power generation devices are deemed suitable alternatives to conventional batteries. These devices can be applied in micro fuel cells, micro gas turbines, and micro-thermo-electric, and thermo-photovoltaic systems [7, 8]. By using structure design to form a low-velocity zone or recirculation zone, the flame stability and combustion performance of the microcombustor can be improved. Peng et al [12] numerically examined the thermal performance of a microcombustion chamber with and without a front cavity and found that the front cavity enhances the stability of the microcombustor. Wan et al [13,14,15,16] numerically investigated the behavior of an H2/air blend in a microcombustion chamber with cavities and found that recirculation and low-velocity zones are formed in the concave cavity. Bagheri et al [17] numerically studied the combustion characteristics of premixed hydrogen/air in microcombustors with different bluff body structures (e.g., semicircular, ellipse, half ellipse, wallblade, and arrowhead) at different inlet velocities and found
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