International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 13 Issue: 01 | Jan 2026
p-ISSN: 2395-0072
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Methane Micro-Combustors: A Sustainable Solution for Portable and Micro-Scale Energy Systems: A Review Ujwal Kant1, Ankit Goyal1, Priyavrat Kumar1, Vikas Gupta1 1Department of Mechanical Engineering, Technocrats Institute of Technology and Science
Anand Nagar, BHEL Oppo site Hathaikheda Dam,Bhopal, Madhya Pradesh 462021 ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - This review paper provides a comparative
store and safer to handle while still achieving high combustion efficiencies [10]. Air micro-combustors, where air serves as the oxidizer, are critical in both premixed and diffusion-controlled configurations. They are often integrated into micro-turbines, thermophotovoltaic power generators, and micro-heaters, enabling devices with power outputs ranging from a few watts to tens of watts [11,12].
analysis of methane and air micro-combustors, emphasizing their design, working principles, performance efficiency, and thermal management strategies. Due to their compact size and high energy density, micro-combustors are emerging as pivotal components in portable power generation and microelectromechanical systems (MEMS). The methane microcombustor operates through sequential stages—fuel-air mixing, combustion in micro-channels, heat generation, and exhaust management—with effective heat recirculation enhancing energy retention. Its performance graph shows that combustion efficiency rapidly approaches 100% at moderate power outputs (~10 W), indicating high thermodynamic efficiency. In contrast, the air micro-combustor employs a similar principle but with enhanced focus on symmetric heat recirculation, leading to sustained high-temperature zones (~700°C) as evident from the temperature-distance profile. Both configurations underscore the importance of precise thermal control, efficient mixing, and flame stability at the microscale. This paper highlights the significance of microcombustor development for miniaturized energy systems and sets the stage for future advancements in clean and decentralized power technologies.
The operation of micro-combustors is governed by classical combustion principles, but with notable modifications due to miniaturization. The quenching distance, which determines the smallest dimension that can sustain a stable flame, becomes comparable to the device size. For methane-air mixtures, this distance is typically around 0.5–1.0 mm [13]. In devices approaching this limit, flame stability is achieved only through preheating of the reactants or catalytic wall interactions. In many designs, premixed methane-air mixtures enter narrow channels where they ignite and stabilize at high temperatures (600–700 °C). Porous media—such as silicon carbide or ceramic foams—are often employed inside the combustion chamber to enhance surface area and enable distributed combustion, which reduces heat loss and increases reaction zone stability [7]. These materials also act as flame holders by preventing flashback or blow-off.
Key word: Methane micro-combustor, micro-combustion, portable power generation.
Flame stability in micro-combustors is determined by the interplay of flow velocity, equivalence ratio (Φ), wall thermal conductivity, and geometry [14]. Unstable flame behaviors— such as FREI (Flame Repetitive Extinction and Ignition)—are commonly observed in micro-scale devices. FREI occurs when the flame cannot remain stationary and oscillates between extinction and reignition due to heat loss and varying residence time [15].
Introduction Micro-combustion is the process of fuel–air combustion in devices with sub-millimeter to millimeter characteristic dimensions. These micro-combustors have attracted significant interest due to their ability to provide compact, high-energy-density power sources for microelectromechanical systems (MEMS), micro aerial vehicles, micro-robots, and thermophotovoltaic systems [1,2]. Hydrocarbon fuels such as methane are particularly appealing because of their high volumetric and gravimetric energy density—approximately 50 times higher than that of conventional batteries—making them ideal for portable energy generation [3]. Methane is also abundant, relatively easy to store, and has well-understood combustion characteristics, making it a prime candidate for microcombustion research [4-9].
Introducing bluff bodies or backward-facing steps in the flow path has been shown to create recirculation zones that act as flame anchors, thereby extending the blow-off limits and stabilizing lean flames (Φ < 0.8) [16]. Numerical studies of methane-air micro-combustors with bluff bodies have confirmed enhanced performance, particularly for portable thermo photovoltaic systems [17]. Heat recirculation is a cornerstone of micro-combustor design. By transferring heat from hot exhaust gases to incoming reactants, the system effectively preheats the mixture and offsets wall losses [9]. Common geometries
Methane/air micro-combustors have been widely studied because they balance fuel availability, safety, and performance. Compared to hydrogen, methane is easier to
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