Experimental Research on Detonation Cell Size of a Purified Biogas-Oxygen Mixture

Abstract

Interest in alternative and renewable energy sources has risen significantly in recent years. Biogas is a prime example of a promising, alternative fuel that might be a possible replacement for fossil fuels. It is a mixture consisting mainly of CH4 and CO2 with various additions. Biogas is easily storable and as such is a more reliable and stable source of energy than solar and wind sources, which suffer from unreliability due to their dependence on weather conditions. In this paper, the authors report experimental results of detonation of a biogas-oxygen mixture. The composition of the biogas was 70% CH4 + 30% CO2 and the experiments were carried out for a range of equivalence ratios (Φ = 0.5 ÷ 1.5) and initial pressures (0.6 ÷ 1.6 bar). The aim of the research was to analyze the cellular structure of detonation. The soot foil technique was used to determine the width of the detonation cells (λ). The conducted experiments and subsequent analysis of the detonation cell size confirm that both the increase in the initial pressure of the mixture or move away from stoichiometric (Φ = 1) composition is accompanied by a decrease in the width of the detonation cell. The authors also argue that due to the unstable cellular structure of the detonation, it is insufficient to report only the average cell size. Instead, the researchers propose more detailed statistical description assured values.

Detonation Cell Size Prediction Using Artificial Neural Networks (ANNs) for Hydrogen/Hydrocarbon/Ammonia/Nitrous Oxide Mixtures

“…Detonation research is generally focused on the safety of engineering applications and industrial processes in the chemical and energy sectors [2,3], and also on the development of hypersonic propulsion systems [4][5][6]. In recent years, there has been a strong focus, especially in the transportation and aerospace industry, to explore greener aviation fuels, that are either carbon-neutral, like biogas [7][8][9], or carbon-free, like hydrogen (H 2 ) [10] and ammonia (NH 3 ) or its blend [11][12][13][14][15], which can also be used as a carrier of green hydrogen. While hydrogen/nitrogen/ammonia/air mixtures have been shown to have similar combustion characteristics as gasoline, they are also susceptible to auto-ignition or detonation phenomena.…”