Combustible gases in coal mines are composed of methane, hydrogen, some multi-carbon alkane gases and other gases. Based on a numerical calculation, the explosion limits of combustible gases were studied, showing that...Combustible gases in coal mines are composed of methane, hydrogen, some multi-carbon alkane gases and other gases. Based on a numerical calculation, the explosion limits of combustible gases were studied, showing that these limits are related to the concentrations of different components in the mixture. With an increase of C4H10 and C6H14, the Lower ExplosionLimit （LEL） and Upper Explosion-Limit （UEL） of a combustible gas mixture will decrease clearly. For every 0.1% increase in C4H10 and C6H14, the LEL decreases by about 0.19% and the UEL by about 0.3%. The results also prove that, by increasing the amount of H2, the UEL of a combustible gas mixture will increase considerably. If the level of HE increases by 0.1%, the UEL will increase by about 0.3%. However, H2 has only a small effect on the LEL of the combustible gas mixture. Our study provides a theoretical foundation for judging the explosion risk of an explosive gas mixture in mines.展开更多
Standard treatments of thermodynamic equilibrium are incomplete. They do not take account of all factors determining equilibrium, cannot explain why many systems do not reach equilibrium and do not discuss the questio...Standard treatments of thermodynamic equilibrium are incomplete. They do not take account of all factors determining equilibrium, cannot explain why many systems do not reach equilibrium and do not discuss the questions of reaching and maintaining equilibrium. The arguments presented here provide a single physical definition of thermodynamic equilibrium that accounts for all factors determining thermodynamic equilibrium for mixtures of combustible gases and air. Based on the standard delrmition of thermodynamic equilibrium, the MBD （Maxwell Boltzmann distribution） and a simple molecular model lead to three possible types of equilibrium. The regions of temperature pressure and composition for each type of equilibrium are defined by the measured values of ignition temperatures and the explosive and flammability limits. How this definition of thermodynamic equilibrium can be extended to all molecular systems is discussed in the following papers.展开更多
An experimental apparatus has been built to measure the flammability limits of combustible gases based on Chinesenational standard GB/T 12474-90. The flammability limits of four binary mixtures of R161/R134a,R152a/R13...An experimental apparatus has been built to measure the flammability limits of combustible gases based on Chinesenational standard GB/T 12474-90. The flammability limits of four binary mixtures of R161/R134a,R152a/R134a, R161/N2 and R152a/N2 were measured with this apparatus at atmospheric pressure and ambienttemperature. The fuel inertization points (FIP) of these mixtures can be found from the envelopes. Comparisonswere made with the literature data; good agreement for most measurements was obtained. R134a was found tohave a better dilution effect than nitrogen in reducing the flammability of hydrofluorocarbons.展开更多
基金Projects 706029 supported by the Cultivation Fund of the Key Scientific and Technical Innovation Project of Ministry of Education of China2007AA04Z332 by the National High Technology Research and Development Program of China
文摘Combustible gases in coal mines are composed of methane, hydrogen, some multi-carbon alkane gases and other gases. Based on a numerical calculation, the explosion limits of combustible gases were studied, showing that these limits are related to the concentrations of different components in the mixture. With an increase of C4H10 and C6H14, the Lower ExplosionLimit （LEL） and Upper Explosion-Limit （UEL） of a combustible gas mixture will decrease clearly. For every 0.1% increase in C4H10 and C6H14, the LEL decreases by about 0.19% and the UEL by about 0.3%. The results also prove that, by increasing the amount of H2, the UEL of a combustible gas mixture will increase considerably. If the level of HE increases by 0.1%, the UEL will increase by about 0.3%. However, H2 has only a small effect on the LEL of the combustible gas mixture. Our study provides a theoretical foundation for judging the explosion risk of an explosive gas mixture in mines.
文摘Standard treatments of thermodynamic equilibrium are incomplete. They do not take account of all factors determining equilibrium, cannot explain why many systems do not reach equilibrium and do not discuss the questions of reaching and maintaining equilibrium. The arguments presented here provide a single physical definition of thermodynamic equilibrium that accounts for all factors determining thermodynamic equilibrium for mixtures of combustible gases and air. Based on the standard delrmition of thermodynamic equilibrium, the MBD （Maxwell Boltzmann distribution） and a simple molecular model lead to three possible types of equilibrium. The regions of temperature pressure and composition for each type of equilibrium are defined by the measured values of ignition temperatures and the explosive and flammability limits. How this definition of thermodynamic equilibrium can be extended to all molecular systems is discussed in the following papers.
基金support of the National Natural Science Foundation of China (NSFC, Grant No.50776096).
文摘An experimental apparatus has been built to measure the flammability limits of combustible gases based on Chinesenational standard GB/T 12474-90. The flammability limits of four binary mixtures of R161/R134a,R152a/R134a, R161/N2 and R152a/N2 were measured with this apparatus at atmospheric pressure and ambienttemperature. The fuel inertization points (FIP) of these mixtures can be found from the envelopes. Comparisonswere made with the literature data; good agreement for most measurements was obtained. R134a was found tohave a better dilution effect than nitrogen in reducing the flammability of hydrofluorocarbons.
