Combustion Characteristics of Small Laminar Flames in an Upward Decreasing Magnetic Field

Yu Xie,Zuohuang Huang,Haishen Zhen,Zihao Liu,Teng Zhou,Zhilong Wei

doi:10.3390/en14071969

Yu Xie, Zuohuang Huang + Show 4 more

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https://doi.org/10.3390/en14071969

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Abstract

The combustion characteristics of laminar biogas premixed and diffusion flames in the presence of upward decreasing magnetic fields have been investigated in this study. The mechanism of magnet–flame interaction in the literature, in which magnetic fields change the behaviors of laminar flames due to the paramagnetic and diamagnetic properties of the constituent gases, is examined and the results are as follows. The magnetic field has no noticeable effect on premixed flames due to low oxygen concentration of the mixed gas at the injection and the relatively high flow momentum. However, due to the diffusion nature of diffusion flames and paramagnetic property of oxygen in ambient air, oxygen distributions are subjected to the gradient of magnetic flux, thus shortening the height of diffusion flames. Results also show that the flame volume is more strongly varied than flame height. Altered oxygen distributions result in improved combustion and higher flame temperature. In the case of current magnet–flame interaction, the magnetic driving force is combined with gravitational force, and a modified gravity g* as well as gravity modification factor G are derived to characterize the paramagnetism theory of oxygen.

Highlights

These results demonstrate that magnetic fields can significantly change flame structure [5,6,7,8,9,10,11,12,13,14], flame temperature [8,10,15,16,17,18,19,20], free radical distribution [21,22,23,24], flame stability [25,26] and CO/NOx /soot emissions as well [6,10,14]
As for flame height change or shape change, which parameter is most sensitive to gradient magnetic field? Second, can flame temperature be varied by gradient magnetic field? Third, as buoyance effect is closely related to gravitational force, can a better parameter be defined to represent the unified effects of magnetic force and gravitational force? For the purpose of solution, this study aims to experimentally investigate laminar flames interacting with a non-uniform, i.e., upward decreasing magnetic field
The second is concerned with visual feature of the flame inside the gradient magnetic field and the analysis of flame temperature

Summary

Introduction

Many studies have been conducted, investigating how the flame behavior is influenced by magnetic fields by using different measurement methods [3,4,5,6,7,8,9,10]. These results demonstrate that magnetic fields can significantly change flame structure [5,6,7,8,9,10,11,12,13,14], flame temperature [8,10,15,16,17,18,19,20], free radical distribution [21,22,23,24], flame stability [25,26] and CO/NOx /soot emissions as well [6,10,14]

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Results

Conclusion