Introduction During the hydrogen production process at hydrogen refueling stations, the mixture of ethanol and hydrogen can easily form a combustible gas, which may explode if ignited by sparks or high temperatures. In order to reduce the risk of explosion during hydrogen production and storage at hydrogen refueling stations, experimental research is essential.
Method The explosion characteristic parameters were analyzed for hydrogen-ethanol-air mixture with different equivalence ratios and ethanol blending ratios at 1 bar and 400 K. By calculating the flammability limit and deflagration index of mixed gas, the degree of explosion hazard was evaluated, and effective safety measures were formulated to reduce the risk of explosion.
Result The experimental research results show that an increase in the equivalence ratio will shorten the explosion time, making it ultimately tend to a stable value. The stable explosion times corresponding to hydrogen volume fractions (30%, 50%, 70%) are 0.03 s, 0.025 s, and 0.019 s. The maximum explosion pressure, maximum pressure rise rate, and deflagration index all increase and then decrease with the increase of equivalence ratio, reaching their peak at an equivalence ratio of 1.3. The flammability limit of the mixed gas continues to decrease with the addition of ethanol, and the decrease in UELmixture (upper flammability limit of mixture) is significantly higher than that in LELmixture (lower flammability limit of mixture). In addition, the maximum pressure rise rate and deflagration index show a significant decreasing trend with the addition of ethanol, and the maximum deflagration index calculated for this research is 11.85 MPa·m/s.
Conclusion The research results have revealed the effect of equivalence ratio and blending ratio on the explosion characteristics of mixed fuels, providing a solid theoretical basis for reducing explosion risks in hydrogen production and storage processes at hydrogen refueling stations.
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