Evaporative Emission Control System (EVAP) and Carbon Canister Modeling

GT-SUITE simulation software includes advanced solvers and components for modeling the entire Evaporative Emission Control System (EVAP), including the flow network, carbon canister, and canister purge valve (CPV).  An activated carbon canister is used to capture hydrocarbon vapor emissions from the fuel tank as part of an EVAP system.  The user has full control over defining the heterogeneous reaction mechanism for modeling the hydrocarbon adsorption and desorption in the carbon canister.  There is increasing interest in optimizing the carbon canister size for hydrocarbon storage, and optimizing the CPV control strategy, especially for turbocharged gasoline direct injection (GDI) engines and hybrid electric vehicles (HEV/PHEV).

GT-SUITE allows you to evaluate how a purge event affects engine performance and emissions. You can also choose when and where to purge during a drive cycle, for example, in an intake manifold under vacuum conditions or upstream of the compressor during boosted conditions. EVAP system components can be modeled in isolation or together with vehicle, engine, thermal management, and control systems, making this tool uniquely suitable for system level optimization and collaborative engineering.  The most important features of this application are as follows:

Product Highlights

  • Automated building of 1D flow network from CAD with GEM3D
  • Advanced Navier-Stokes solver for accurate gas dynamics
  • Advanced carbon canister modeling features
    • Highly flexible and intuitive user interface for entering any reaction mechanism, including heterogeneous reactions for modeling the adsorption and desorption of any hydrocarbons
    • Packed bed geometry input with Friction Factor and Nusselt/Sherwood Number as a function of particle Reynolds Number (e.g. Ergun Equation) for predicting pressure drop and heat/mass transfer
    • Quasi 2D/3D carbon canister modeling with axial and radial mesh control
    • Built-in direct and DOE optimizers for reaction rate kinetic parameter calibration, including genetic algorithm
    • Fast and efficient implicit flow solver, faster than Real Time (RT) for loading and purging applications
  • Axial species diffusion using the implicit flow solver (fuel vapor diffusing from tank to canister)
  • Various levels of fidelity for CPV modeling including:
    • Simple solenoid valve modeling using open/close/lift profiles
    • Detailed component level modeling to predict valve performance and dynamics based on geometry. This integrates fluid dynamics, mechanics, and optionally electromagnetics in a single model.
  • Real Time Capable run times

Advanced Features and Applications

  • Carbon canister fuel vapor loading and purging
  • Diurnal test cycle, modeling the flow and diffusion of fuel vapor from the fuel tank to the carbon canister during low/zero flow conditions
  • Canister Purge Valve (CPV) design and optimization, duty cycle analysis
  • Canister vent (check) valve modeling
  • Detailed fuel tank model including fuel evaporation (contact us for more information)
  • Air Induction System Hydrocarbon Trap (AIS HC Trap) modeling, including diffusion of fuel vapor from the cylinders and ports to the HC vapor adsorbing catalytic material in the air box (contact us for more information)
  • Other applications using a similar modeling approach in GT-SUITE:
    • Brake line dryer in the air brake system of trucks and trailers
    • Adsorption-based thermal battery for adsorbing water or refrigerant, and releasing later for cooling ->HEV/EV applications
    • CO2 storage and sequestration