Venting of gas explosion through relief ducts: Interaction between internal and external explosions

Duct-vented hydrogen–air deflagrations: The effect of duct length and hydrogen concentration

“…Transient higher overpressure in the duct than that in the vessel (PS2 > PS1), as shown in Fig.3(a), was observed in all tests with ducts. This phenomenon has been confirmed in previous research to be caused by burn-up in the duct [16,20]. Concretely, when the vent cover was opened, the flame was still far from vent as shown in Fig.…”

“…It has been found that frictional loss of the outflow and inertia of the gas column in the duct, Helmholtz oscillations in the vessel, and burn-up in the duct are responsible for the effects of ducts on explosion venting [10,12,14,15]. The results of numerical investigations have demonstrated that burn-up in the duct is the dominant factor resulting in higher severity of duct-vented explosions [16,17], and the conclusion has been confirmed by experimental results [18][19][20].…”

“…Fig.5 shows that duct length has no apparent effect on the maximum reduced overpressure due to its slow burning rate. However, for hydrogen concentration ranging from 25% to 55%, the maximum overpressure increased quickly with an increase in L/D to 14.3, which is attributed mainly to the turbulent burn-up in the duct [16][17][18][19][20]. Fig.…”

Explosion parameters of methanol–air mixtures

“…The maximum explosion pressures, the maximum rates of pressure rise, the explosion delay time and the deflagration index are important values for vent area design [34,35], for the explosion protection measure ''constructive explosion protection'' [33] and for the characterization of explosion transmission between interconnected vessels [36,37] methanol-air mixtures in a wide range of initial conditions are needed for extending databases of explosion parameters of fuels.…”

The design of duct venting of gas explosions

“…Finally, regarding the tube length, it should be noted that the effects of increasing L t are negligible on f already at value of L t as low as 0.2 m. In our previous study [26], we run ad hoc numerical simulations eventually showing that in the conditions of the experiments of Ponizy and Leyer [6, 7], the frictional losses play a negligible role in the development of the pressure history and in the pressure peak with respect to burn‐up. The pressure loss Δ P L in the tube maybe calculated according to the following equation [27]: where the pedix in and out refer to the initial and final section of the tube, ρ and u are the gas density and velocity, K is the pressure loss coefficient for sudden flow restriction or enlargement, and f is the friction factor for the flow in the duct evaluated by means of traditional relationship.…”