Effect of obstacle on the H2/CO/Air explosion characteristics under lean-fuel conditions

Effect of ignition, initial pressure and temperature on the lower flammability limit of hydrogen/air mixture

Influence of venting coefficient on disastrous effects of aluminium powder explosions

Review and prospect the development of dust suppression technology and influencing factors for blasting construction

In the real scenarios, explosions generally occur under turbulent environments. In this study, the turbulence is generated by introducing inert gas jets, and the interaction between jet turbulence and inert gas dilution is extremely complicated under different conditions. Therefore, the aim of this study is to investigate the influence of gas jets on explosion behavior of hydrogen-air mixtures with various hydrogen concentrations (from 10% to 70%) at different initial pressures (i.e., 50 kPa, 100 kPa, 150 kPa, 200 kPa), and a series of experiments are conducted in a standard 20 L spherical explosion chamber at environmental temperature 300 K. The effect of gas jets on explosions of hydrogen-air mixtures with various hydrogen concentrations at initial pressure of 100 kPa is first studied, the experimental results illustrate that jet has minor impact on the explosion behavior when hydrogen concentration ranges from 20% to 70%. However, the enhancement effect of gas jets on the reaction process is significant as hydrogen concentration is 10%. Therefore, the impact of various gas jets (i.e., CO2, and N2) on explosion behavior at different initial pressure is mainly examined as hydrogen-air mixtures are near the lower explosive limits. It is found that the enhancing effect of gas jets on explosion behavior is profound for hydrogen-air mixtures at higher initial pressure, however, the suppression effect caused by the higher concentration of inert gas could balance the promoting effect by turbulence at lower initial pressure. Moreover, the encouraging effect of CO2 jet is more apparent than that of N2 jet when jet duration time is relatively short, because the turbulence intensity induced by CO2 is greater due to its larger molecular weight. 

The effect of gas jets on the explosion dynamics of hydrogen-air mixtures

Investigations on unconfined large-scale methane explosion with the effects of scale and obstacles

Characteristic evaluation of aluminum dust explosion venting with high static activation pressure

Experimental investigation on PMMA dust explosion venting at elevated static activation pressure

This work is aimed at investigating the lower flammability limits (LFLs) of ethanol, acetone, and ethyl acetate vapor mixtures in air with various mole fractions. The LFLs were measured by a self-made experimental apparatus. Besides, a theoretical calculation model of LFL based on adiabatic constant pressure was established. The heat release, adiabatic flame temperature and the sensitivity of mass burning rate on LFL are analyzed. The results indicated that as the mole fraction of a single substance in a binary mixture or a ternary mixture increases, the LFL changes monotonically. The calculated LFLs are in good agreement with the experiment. The maximum absolute deviation and relative deviation are 0.2% and 6.47% respectively. The trends of heat release and adiabatic flame temperature (AFT) are consistent, meanwhile, the trends of LFL are opposite to them. Besides, the trend of the total peak of heat release rate at LFL is consistent with the heat release. H + O2 O + OH mainly reduces the heat release rate, and CH3 + O CH2O + H mainly increases the heat release rate. The sensitivity coefficients of the maximum main chain branching reaction H + O2 O + OH and the main termination reaction H + O2 (+M) HO2 (+M) of the mass burning rate at the LFL are almost the same.

Lower flammability limits of ethanol, acetone and ethyl acetate vapor mixtures in air

Venting is an effective way to prevent harmful dust explosions, but the existing prediction methods are imprecise and are suitable only for applications with low activation pressures. A new method is proposed for predicting pressures based on an analysis of energy losses at high activation pressures and verified by aluminum dust explosion experiments. Compared with the experimental results, the results of the new model are relatively stable under working conditions with different activation pressures and venting areas. Based on the analysis of energy losses, the changes in the energy loss rate, temperature, and venting velocity during venting are found to be asynchronous. The thermal energy loss, which accounts for over 80 percent of the total, is expected to be larger than the kinetic energy loss. The thermal energy loss rate changes rapidly during venting, while the kinetic energy loss rate remains relatively stable. The new model is more accurate than the NFPA68 standard, which fails to consider the thermal energy loss. Neglecting the thermal energy loss may result in an underestimation of the pressure reduction; this error increases with decreasing activation pressure.

Xiangfeng Chen

Papers

Investigations on unconfined large-scale methane explosion with the effects of scale and obstacles

Characteristic evaluation of aluminum dust explosion venting with high static activation pressure

Experimental investigation on PMMA dust explosion venting at elevated static activation pressure

Lower flammability limits of ethanol, acetone and ethyl acetate vapor mixtures in air

A new prediction method for dust explosion venting at high static activation pressures