Method for Filling a Tank with Pressurized Gas

A method for filling a tank with pressurized gas, the tank (3) to be filled being supplied with pressurized gas from at least one source (1) and via a filling pipe (2) provided with at least one control valve (5), in particular gaseous hydrogen, in order to achieve a predetermined target filling rate (ρf) expressed as the current density of gas (ρ(ti)) in the tank with respect to a target density (ρf), the filling being interrupted when a measured or estimated physical quantity (ρ(ti)) of the gas in the tank corresponds to the target filling level (ρf) or when the temperature (T(ti)) in the tank reaches a given maximum threshold (Tmax), the method comprising:

• a step of measuring the initial pressure (P(t0)) in the tank before filling,
• a step of determining the initial quantity (m(t0)) expressed by mass of gas in the tank before filling,
• a step of measuring the current pressure (P(ti)) in the tank during filling,
• a step of determining the current quantity (Q(ti)) expressed as the mass of gas transferred into the tank during filling,
• a step of calculating the current quantity (m(ti)) expressed for example as the mass of gas in the tank during filing,
• a step of determining the current temperature (T(ti)) of the gas in the tank during filing,
• the method being characterised in that, for the step of determining the current temperature (T(ti)) of the gas in the tank, said temperature (T(ti)) is expressed and calculated solely as a function of the variables consisting of the current pressure (P(ti)) in the tank and the current quantity (m(ti)) of gas in the tank;
• the expression of the current temperature (T(ti)) as a function of the current pressure (P(ti)) and the current quantity (m(ti)) of gas in the tank being obtained from the state equation for the real gases in the tank P(ti)·V·105=Z·n·R·T(ti), in which P(ti) is the pressure of the gas in the tank at time ti in bars, V the volume of the tank in m3, R the perfect gas constant equal to 8.314 in J/(mol·K), T(ti) the temperature of the gas in the tank at time ti in Kelvin (K) and Z the unitless compressibility factor, this compressibility factor Z being expressed as a function of the temperature T(ti) and the pressure P(ti) of the gas in the tank according to a first degree formula Z(ti)=(e·T(ti)+f)·P(ti)+g, in which e, f and g are coefficients predetermined empirically with e in bars−1·K−1, f in bar−1, g unitless.