CFD simulations of dust dispersion in the 1 m3 explosion vessel

Computational assessment of biomass dust explosions in the 20L sphere

“…CFD methods are especially well suited for understanding deflagration development and propagation inside equipment or through complex structures [12]. To calibrate these models, a frequent practice is to first perform CFD simulations of dust dispersion and explosion experiments in the standardized apparatus: the Hartmann tube [44,45], the 20L Siwek sphere [46][47][48], or the 1m 3 ISO vessel [49]. These models can reduce the time consuming labor and expensive costs of experimental testing.…”

On the pyrotechnic ignitors role in dust explosion testing: Comparison between 20 L and 1 m3 explosion vessels

“…To assess the role of the hot and dense dispersed particles cloud generated by pyrotechnic ignitors in the 20 L and 1 m 3 vessels, we used a CFD model previously developed and validated, whose details are reported elsewhere. 21,24 In both cases, we assumed the generated particles cloud as a central hot core at a temperature equal to 2000 K and radius equal to 0.13 m (i.e., the flame radius at 10000 J) and simulated the evolution of the temperature maps. The initial conditions (i.e., pressure, turbulence, temperature, etc.)…”

“…[24][25][26][27][28] This issue appears to be solved in the 1 m 3 vessel since the variation range of turbulent kinetic energy from the center to the wall at the ignition delay time is very narrow. 21,22,29 In order to neglect the underdriving phenomenon in the 20 L sphere, we considered both ature value is equal to 500 K. Conversely, in the 1 m 3 vessel, the temperature does not uniformize and its value is higher in the center of the sphere and equal to 770 K. These results are the consequence of the higher turbulence level attained in the 20 L vessel that affects the mixing of heat thus uniformizing the temperature, as shown in Figure 4. 21,22 Therefore, the heat dissipation is higher in the 20 L, not only due to the heat loss toward the outside, given the higher value of the surface-to-volume ratio, but also due to the high level of turbulence.…”

“…21,22,29 In order to neglect the underdriving phenomenon in the 20 L sphere, we considered both ature value is equal to 500 K. Conversely, in the 1 m 3 vessel, the temperature does not uniformize and its value is higher in the center of the sphere and equal to 770 K. These results are the consequence of the higher turbulence level attained in the 20 L vessel that affects the mixing of heat thus uniformizing the temperature, as shown in Figure 4. 21,22 Therefore, the heat dissipation is higher in the 20 L, not only due to the heat loss toward the outside, given the higher value of the surface-to-volume ratio, but also due to the high level of turbulence. Conversely, in the case of flame propagation controlled by heat diffusion as in the case of metal dusts, the heat dissipation occurring in the 20 L vessel may have a significant impact on the flame propagation speed and then on the severity of the explosion.…”

“…20 Regarding the turbulence effect, in our recent works, the increase of the deflagration index in the 20 L vessel for organic dusts compared to that in 1 m 3 vessel was further justified by the effect of high and not uniform turbulence level on the flame propagation. 21,22 In this work, we aim at quantifying the effect of the ignition energy (IE) provided by pyrotechnic ignitors and of the heat propagation of the hot and dense dispersed particles cloud generated by them on the 20 L and 1 m 3 vessels measurements, to justify the contradictory results found. To determine the role of the IE, we run explosions in the 20 L vessel, by using dust-free air, just measuring the pressuretime history due to the pyrotechnic ignitors action at different values of the IE.…”