Intercomparison between LH2, LNG and pressurized NH3 dispersion using an adiabatic mixing approach. (22nd January 2022)

• Record Type: Journal Article
• Authors: Venetsanos, A.G.; Boulougouris, G.C.; Giannissi, S.; Krassa, Th.; Andronopoulos, S.; Bartzis, J.G.
• Is Part Of: International journal of hydrogen energy. Volume 47:Number 7(2022)
• Page Start: 4943
• Page End: 4958
• Publication Date: 2022-01-22
• Subjects: LH2 -- LNG -- NH3 -- Flashing -- Phase change -- Oxygen enrichment; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.11.071
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: The differences between LH2, LNG and pressurized NH3 dispersion are investigated using a new adiabatic mixing model which is based on Raoult's law and PH-flashing techniques for ideal mixtures and accounts for phase changes of the released substance and all ambient air components. Model validation is performed first against recent LH2 experiments and older experiments involving LNG and NH3 releases with reasonable agreement. The intercomparison analysis performed next assumes the given substance released at its boiling point temperature either as liquid or vapour. Ambient air is assumed composed of N2, O2 and H2 O with relative humidity either zero or 100%. The performed comparative assessment addresses the temperature versus molar fraction dependence, the condensed phase appearance conditions, the variation of the amount of the condensed phase in the mixture and its composition and finally important safety related parameters like the O2 /N2 and fuel/(fuel + O2 ) ratios. It is found that for all three substances considered the temperature-molar fraction relation is significantly affected by source vapour quality and to less but still important extent by ambient air relative humidity. It is also found that for H2 releases the stoichiometric ratio can be reached in the condensed phase (due to O2 enrichment) and that this is not possible for CH4 and NH3 releases. The present model can be used as an engineering tool for adiabatic mixing calculations. Highlights: The new adiabatic mixing model accounts for phase change of all mixture components. The model is validated against LH2, LNG and NH3 dispersion experiments. The temperature-molar fraction relation depends strongly on source vapour quality. O2 enrichment of the dry air in the condensed phase is quantified. Stoichiometry in the condensed phase can be reached for H2 but not for CH4 and NH3 .