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The main part of a micro-thermophotovoltaic (MTPV) system is the micro combustor (MC). In this work, the performance of the traditional micro combustor (TMC) and the micro combustor with twisted tape (MCTT) is investigated numerically under various inlet velocities (9 m/s-12 m/s), H 2 /air equivalence ratios (0.7–1.0), lengths of the twisted tape (4 mm–16mm), and pitches (4 mm, 5.33 mm and 8 mm). The results show that compared with the TMC, the MCTT with a 16 mm long twisted tape has a 114.7 K, 12.2 W and 15.0% increase in the mean outer wall temperature T ¯ w , radiation power P emitter and emitter efficiency η mc , respectively, at v in = 9 m/s. The outer wall temperature T ow is more uniform when the length of the twisted tape is 4 mm or 8 mm, the maximum drop in temperature standard deviation is 38.9 K when v in = 9 m/s. When the equivalence ratio φ ha is less than 0.9, the η mc is not significantly improved with the increase of the length of the twisted tape. Overall, the MCTT offers better promise for applications in MTPV systems than the TMC. • A micro-cylindrical combustor with twisted tape is developed. • How to enhance combustion performance of the developed combustor is investigated. • The developed combustor has better potentiality for applications in MTPV system. [ABSTRACT FROM AUTHOR]

With the development of microfabrication technology and micro devices, the demand for Power Micro Electro Mechanical System (Power MEMS) is ever-increasing. However, traditional chemical batteries are not suitable for Power MEMS due to their low energy density. The combustion of hydrogen and hydrocarbon fuels offers a more promising alternative to conventional batteries. However, micro combustion faces the problems of flame instability and low combustion efficiency. Therefore, improving flame stabilization and combustion efficiency in micro combustions is necessary. Studies have made considerable progress in these aspects over the last decade. This paper summarized these studies and classified the optimization schemes according to flame stabilization and combustion efficiency. Besides, research on the Field Synergy Principle was discussed. The synergy between the flow field and temperature gradient field in the micro-scale domain will become a key research area in the future. It is proposed to insert porous media in MTES and MTPVS and adopt catalytic combustion. Adding hydrogen to the mixed gas was recommended. The equivalence ratio of the mixed gas in the range of 0.9–1.1 would be best. The equivalence ratio is the ratio of the theoretical requirement of air with complete combustion to the actual supply of air. • Factors affecting the flame stability in micro combustors are summarized. • Factors affecting the residence time in micro combustors are summarized. • Factors affecting the global efficiency of micro combustors are summarized. • Future works to improve the performance of micro combustors are introduced. [ABSTRACT FROM AUTHOR]

• Combustion stabilization technologies for micro/meso-scale combustors are reviewed. • Flammable range is expanded by applying combustion stabilization technology. • Combustion stabilization technology improves outer wall temperature distribution. • Combustion stabilization technology effectively reduces pollutant emissions. • Combustion stabilization technology improves energy conversion efficiency. Owing to its high energy density, the combustion-based micro thermophotovoltaic system has promising prospects and becomes the most potential substitute for conventional power generation systems. As one of the most critical components in micro thermophotovoltaic systems, however, micro/meso-scale combustors are still confronted with many challenges due to the scale effect. Therefore, it is of great significance to develop combustion stabilization technologies for micro/meso-scale combustors. During the past two decades, many researchers have proposed various combustion stabilization technologies, which have been reviewed in this work. According to the working principle, different micro/meso-scale combustion stabilization technologies can be classified into three categories: heat recirculation, flow recirculation, and combustion optimization. The results indicate that these technologies can effectively expand the flammable range and have a positive effect on the stable combustion in micro/meso-scale combustors. Furthermore, the working performance of micro/meso-scale combustors, including thermal performance, emission performance, and energy conversion performance, has been evaluated. The results demonstrate that the application of different combustion stabilization technologies to micro/meso-scale combustors effectively increases the outer wall temperature distribution, reduces CO/NO X emissions, and improves the combustion/radiation efficiency. Finally, the challenges and prospects of future work are outlined. This work expounds on the research progress of micro/meso-scale combustors for micro thermophotovoltaic systems, which provides references for subsequent research and applications. [ABSTRACT FROM AUTHOR]