Abstract
A controlled fire burner was constructed where various natural vegetation species could be used as fuel. The burner was equipped with thermocouples to measure fuel surface temperature and used as a cavity for microwaves with a laboratory quality 2-port vector network analyzer to determine electrical conductivity from S-parameters. Electrical conductivity for vegetation material flames is important for numerical prediction of flashover in high voltage power transmission faults research. Vegetation fires that burn under high voltage transmission lines reduce flashover voltage by increasing air electrical conductivity and temperature. Analyzer determined electrical conductivity ranged from 0.0058 - 0.0079 mho/m for a fire with a maximum temperature of 1240 K.
Highlights
When a weakly ionized medium is irradiated with electromagnetic energy, electrons in the medium gain a directed drift velocity in the direction opposite that of the applied electric field of the incident wave
The concentration of electrons, which can be up to 1018 m-3 in a vegetation fire [1] and ions which are in motion both contribute to the electrical conductivity of the weakly ionized fire
The electrical conductivity could have been higher for very high intensity vegetation fires, as it is temperature and ionization dependent
Summary
When a weakly ionized medium is irradiated with electromagnetic energy, electrons in the medium gain a directed drift velocity in the direction opposite that of the applied electric field of the incident wave. The concentration of electrons, which can be up to 1018 m-3 in a vegetation fire [1] and ions which are in motion both contribute to the electrical conductivity of the weakly ionized fire. Vegetation fires are diffusion flames which are seeded with plants’ omnipresent alkali. Electrical conductivities of flames seeded with alkalis have been determined, e.g., in Olson et al [2] and Schneider et al [3]. According to [2], radio frequency measured electrical conductivities of high temperature hydrogen-oxygen flames seeded with alkalis were in the range of 0.04-0.27 mho/m. X-band microwaves were caused to propagate in the vegetation fire to determine electrical conductivity from network analyzer measured S-parameters
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
