Influence of initial pressure and temperature on flammability limits of hydrogen-air

摘要

This paper presents data on the lower and upper flammability limits of hydrogen-air mixtures at elevated temperature and pressure. A 5-L explosion vessel, an ignition system, and a transient pressure measurement sub-system were used in this study. Through a series of experiments carried out, the lower and upper flammability limits of hydrogen-air mixtures at different initial pressures and temperatures have been studied and the influence of initial temperature and pressure on the lower and upper flammability limits of hydrogen-air mixtures has been analysed and discussed. It was found that the decrement of the LFLs of hydrogen-air with the initial temperature from 21 to 90 ℃ at the initial pressure of 0.1 MPa is less than 1%, the decrement of the LFLs with the initial temperature from 21 to 90 ℃ at 0.2 MPa is less than 1%, the decrement of the LFLs with the initial temperature from 21 to 90°Cat 0.3 MPa is less than 0.66%, and the decrement of the LFLs with the initial temperature from 21 to 90 ℃ at 0.4 MPa is less than 0.25%. The lower flammability limits of hydrogen-air mixtures at the pressures of 0.1 and 0.4 MPa are 4 and 1.25%(V/V), respectively. The upper flammability limits of the hydrogen-air mixtures increase with the initial pressure and temperature. The upper flammability limit of the hydrogen-air mixtures at 90 ℃ and 0.4 MPa reaches 93%(V/V) which is much higher than that (76%(V/V)) at 21 ℃ and 0.1 MPa.