CPC F17C 13/026 (2013.01) [F17C 13/025 (2013.01); F17C 13/028 (2013.01); F17C 2221/033 (2013.01); F17C 2223/0153 (2013.01); F17C 2250/032 (2013.01); F17C 2250/0426 (2013.01); F17C 2250/043 (2013.01); F17C 2250/0439 (2013.01); F17C 2250/0447 (2013.01); F17C 2250/0626 (2013.01); F17C 2265/031 (2013.01); F17C 2270/0105 (2013.01)] | 17 Claims |
1. A computer-implemented method for computing a transition parameter of a liquefied gas storage medium, the storage medium comprising at least one sealed and unrefrigerated tank (2, 4, 5, 6, 7 or 11) equipped with a safety valve (20), the transition parameter characterizing an evolution of a two-phase mixture (13) contained in the sealed and unrefrigerated tank between an initial state (8) and a final state (9), the two-phase mixture including a liquid phase and a vapour phase, wherein said transition parameter is selected in a group consisting of a duration of the transition τ, a liquid bleeding rate ml or a vapour bleeding rate mv, the method comprising the steps of:
determining, for the liquid phase and the vapour phase in the initial state (8), initial mass densities ρl,i and ρv,i, and initial internal mass energies Ul,i and Uv,i on the basis of an initial liquid phase temperature Tl,i, an initial vapour phase temperature Tv,i, an initial vapour phase pressure Pi, an initial liquid phase volume Vl,i and an initial liquid phase composition xl,i;
determining, for the liquid phase and the vapour phase in the final state (9), final mass densities ρl,f and ρv,f, final internal mass energies Ul,f and Uv,f, and final mass enthalpies Hl,f and Hv,f on the basis of an equation of state and a final vapour phase pressure Pf, the final pressure of the vapour phase Pf being less than or equal to the setting pressure of the safety valve (20) and greater than or equal to the initial pressure of the vapour phase Pi;
computing the transition parameter using the following equation:
τ(Q+mv(Hv,f−Ū)+ml(Hl,f−Ū))=ρl,iVl,i(Ū−Ul,i)+ρv,i(Vt−Vl,i)(Ū−Uv,i)+ρv,fVt(Uv,f−Ū)
in which Q corresponds to an energy contribution by heat ingress through the walls of a tank per unit of time, Vt corresponds to a total volume of the tank and with
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