Method for Calculating Hydrogen Storage Inventory

A method for calculating inventory of gaseous hydrogen contained in a stationary storage vessel comprising:

• empirically determining a time constant (τ) for said stationary steel storage vessel;
• computing an alpha value (α) from said time constant by time constant equation
• τ=1/α
• measuring an external ambient temperature of said stationary storage vessel (Ti);
• applying a first order filter to said external ambient temperature to compute a calculated temperature (Tc) by temperature equation
• Tc=α*Tc′+(1−α)Ti
• where Tc′ is a previous calculated temperature;
• determining a measured pressure (P);
• and
• calculating a density (d) from said calculated temperature and said measured pressure with an empirical equation
• d
• =
• 1.7941
• *
• (
• P
• )
• (
• Tc
• +
• 273.15
• )
• -
• 0.04036
• *
• (
• P
• )
• ^
• 1.6
• (
• Tc
• +
• 273.15
• )
• ^
• 1.5
• where d is in kg/m3;
• P is in psig;
• and T is in ° C.