Effects of hydrogen concentration and explosion vent on the deflagration characteristics of the unpremixed H2/ TiH2 dust layer

Abstract

In this study, the secondary explosion and explosion venting characteristics of TiH2 dust cloud induced by H₂ explosion with different concentrations were studied using a 27 L cubic explosion vessel. Experimental results showed that the explosion peak pressure of the unpremixed H₂/TiH₂ dust layer respectively increased by 33.0 % and 4.0 % when the concentrations of H₂ were 10 vol% and 20 vol%, TiH₂ dust played a role of positive feedback effect on the explosion pressure; While when H₂ concentrations were 30 vol%, 40 vol% and 50 vol%, the explosion peak pressure of the mixture would decreased by 9.9 %, 4.4 % and 1.3 %, while had a negative feedback effect on the explosion pressure. As the H₂ concentration increases, the maximum flame area of the TiH₂ dust cloud ignited by an H₂ explosion first rises and then decreases, reaching a peak of 350.13 cm2 at an H₂ concentration of 30 vol%. As the H2 concentration increases, the maximum average temperature of the TiH₂ dust cloud induced by H₂ explosion first rises and then decreases, reaching a peak value of T_max = 2572 K at an H₂ concentration of 20 vol%. The explosion vent effectively reduces the peak pressure of H₂ explosions in enclosed spaces, with a maximum reduction of 19.2 %. When TiH₂ dust is present in the space, the reduction reaches up to 16.9 %. Concurrently, the flame area and duration of TiH₂ deflagration are significantly diminished. The explosion vent demonstrates a pronounced effect in suppressing secondary explosions of TiH₂ dust. By reducing the pressure of the primary explosion, it inhibits the entrainment of TiH₂ dust, thereby mitigating the hazards associated with secondary TiH₂ dust explosions. The research achievement had an important guiding significance for the prevention and control of dust explosion of hydrogen storage alloy powders.