(720a) Hydrogen Car Fill-up Modeling Phase 2
A real-life hydrogen fuel dispensing system is mathematically modeled in a modular fashion and based on thermodynamics and transport phenomena fundamentals. The Redlich-Kwong equation of state (RK-EOS) was employed as a thermodynamic model for hydrogen since it behaves as a non-ideal gas due to the temperature (0oC to 100oC) and pressure conditions (1 bar to 1000 bar). The modules of the system are: one station storage tank, vehicle tank, solid pipe segments (assumed to be straight), and two isenthalpic valves. The station storage tank is modeled by two ordinary differential equations (mass and energy balance). Pipe segments were modeled by one ODE (energy balance) while one of the valves was modeled by one algebraic equation (isenthalpic condition). Then, the vehicle tank was model by two ODEs (mass and energy balance) and two non-linear algebraic equations (RK-EOS and Joule-Thompson expansion) resulting in a Differential-Algebraic-Equation (DAE) problem. Subsequently, a dynamic model, including all modules models, was developed in order to simulate the hydrogen pressure, temperature, and flowrate as a function of time. This dynamic model is an improvement of the simple model employed before since it eliminates the constant hydrogen feed pressure, temperature, and flowrate conditions, and now it considers two tanks connected to each other.