Patent Document ID: 8594954
Application ID: 12844219
Patent Flag: 1

Claim One:
1. A method of estimating a volume (Vtk) of a pressurized gas tank, comprising: a) a step of determining a pressure (Ptk(t 1 )) in the tank, b) a step of determining a quantity (ntk(ti)) of gas contained in the tank at a first time (t=t 1 ), c) a step of transferring a checking stream of gas into the tank over a discrete period (t 2 −t 1 ) from a pressurized gas source in fluid communication with the tank thereby increasing the pressure in the tank to produce a further pressurized tank, d) a step of determining a pressure (Ptk(t 2 )) in the further pressurized tank, e) a step of determining a quantity (Q=ntk(t 2 )−ntk(t 1 )) of gas transferred from the source into the tank during step c), and f) a step of calculating the estimated volume of the tank based on: the pressure (Ptk(t 1 )) in the tank determined in step a), the quantity (ntk(ti)) of gas contained in the tank at a first time (t=t 1 ) determined in step b), the pressure (Ptk(t 2 )) in the further pressurized tank determined in step d), and the quantity (Q=ntk(t 2 )−ntk(t 1 )) of gas transferred from the source into the tank determined in step e), g) a step of filling the further pressurized gas tank based on the estimated volume (Vtk) to a desired final quantity of the gas in the pressurized gas tank to produce a final pressurized gas tank, wherein in step f), the calculation assumes that step c) is an adiabatic process to produce the further pressurized tank, wherein the calculation of step f) assumes an enthalpy of the gas in the tank after the checking stream of gas has been transferred (ntk(t 2 ).Htk(t 2 )) is equal to the sum of a) the enthalpy of the gas in the tank before the checking stream of gas is transferred (ntk(t 1 ).Htk(t 1 )) and b) the enthalpy of the gas transferred from the source in the tank upon transfer of the checking stream of gas ((ntk(t 2 )−ntk(t 1 )).Hsi(t 1 )), and wherein the calculation uses a model of the enthalpy given by the following equation: 
 H=m·T ( ti )· P ( ti )+ q where m=A.T(ti)+B and q=C.T(ti)+D in which T(ti)=temperature (in kelvin) of the gas at time t=ti; P(ti)=pressure (in pascals) of the gas at time t=ti; A (in J.Pa −1 .K −1 ), B (in J.Pa −1 ), C (in J.K −1 ) and D (in J) are determined coefficients expressing the enthalpy H of the gas as a function of its pressure and its temperature.