The Influence of 90 Degree Bends in Closed Pipe System udon the Explosion Properties Using Hydrogen-Enriched udMethaneud

摘要

This work sought to evaluate the explosion severity on hydrogen enrichment in methane-air mixture udexplosion. For this purpose, different hydrogen mixture compositions ranges between 4 to 8% v/v were udconsidered. This work was performed using CFD tool FLACS that has been well validated for safety udstudies on both natural gas/methane and hydrogen system. FLACS is used to validate the maximum udpressure and flame speed predicted by the CFD tool for combustion of premixed mixtures of methane and udhydrogen against the experimental data. Experimental work was carried out in a closed pipe containing 90-uddegree bends with a volume of 0.41 m3ud, operating at ambient conditions. From the experiment udobservation, it shown that the coupling effect of bending and thermal diffusivity gave the dramatic influent udon explosion severity in hydrogen-methane/air at very lean concentration. However, simulation results udshowed that FLACs is under-predicting the overpressure at very lean concentration of hydrogen in udmethane/air mixtures. It can be said that lower hydrogen content in methane/air mixture limits the udhydrogen diffusivity, leading to the decrease of the burning rate and flame speeds. It is also demonstrated udthat the presence of 90-degree bend in closed pipe system increases the simulated flame speeds to the udfactor of 2-3, as compared to the experimental data. There are significant discrepancies between udexperimental and simulation, however, the results seem conservative in general. ud