Fuel and Combustion

Fuel and Combustion

Numerical Investigation of Modular Structures in a U-Shaped Micro-Combustor on Combustion Characteristics of Hydrogen-Air Premixed Mixtures for Micro thermophotovoltaic Applications

Document Type : Original Article

Authors
Hamed Mohammadi 1
Alireza Alipoor 2
1 Student of Shiraz University
2 Department of Mechanical Engineering, Shiraz University,, Shiraz, Iran
10.22034/jfnc.2025.490472.1416
Abstract
Enhancing the flammability limit in micro-combustors can be effectively achieved through the implementation of modular structures, facilitating their application across varying power outputs. This study examines the performance of different geometries, including a single straight tube, a single U-shaped tube, and a modular double U-shaped tube configuration. The effects of inlet flow velocity, equivalence ratio, and thermal conductivity coefficient on the combustion characteristics of a hydrogen-air premixed mixture are investigated. The results demonstrate that the use of single U-shaped tubes and modular double U-shaped tube configurations increases the flammability limit for inlet velocities by 27% and 54%, respectively, compared to single straight tubes. Additionally, the modular structure reduces flame stretch and the flame front distance from the inlet, enhancing flame stability. A comparison of geometries reveals that the single U-shaped tube achieves the highest total thermal efficiency, whereas the single straight tube exhibits the lowest. Furthermore, for the straight tube, single U-shaped tube, and dual U-shaped tubes the highest total thermal efficiency is observed at an equivalence ratio of 0.8, beyond which efficiency decreases. Analysis of the thermal conductivity coefficient indicates that increasing this parameter enhances total thermal efficiency across all geometries, with the highest efficiency achieved using steel with a thermal conductivity coefficient of 12.63 W/m·K.
Keywords
Hydrogen
Flammability Limit
Radiation Efficiency
Micro thermophotovoltaics

Subjects

 
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