AML:FC

Advanced Model Library for Fuel Cells (AML:FC)

Technology

The AML:FC models incorporate state-of-the-art first-principles representations of anode, cathode and electrolyte that take into account heat and mass transfer, chemistry and electrochemistry to an unprecedented level of detail.

Cell and stack models are constructed from set of component models that take into account all key phenomena and their interactions. The set of basic building block models is listed below .

Once a cell model has been constructed, it is typically validated against laboratory and test rig data to estimate values for key system parameters. Validated models can provide an exceptionally high degree of predictive accuracy.

AML:FC models are inherently dynamic, so it is possible to analyse transient behaviour during start-up and load change. gPROMS's advanced optimisation facilities mean that key variables can be optimised directly rather than via trial-and-error simulation.

Flexible configuration

Since the AML:FC is a system of component models it is possible to create virtually any cell or stack configuration using a consistent set of models.

For example it is possible to:

create 1-D, 2-D or 3-D representations, depending on how key quantities vary across the cell surface. For example, a cell in which air and fuel flow are co-current or counter-current usually requires only 2-D modelling as there is little variation over the depth of the cell.
Account for any channel geometry ,such as rectangular, arched and trapezoidal channels, using the same model
select from co- or counter-current flow arrangements for air, fuel and cooling channels
construct stack models comprising any number of cells
include fuel processing and any other ancillary equipment in a flowsheet
incorporate heat integration with the environment ,fuel processing or other ancillary equipment in a variety of different ways
include control systems
develop and model operating procedures for design of operating policy – for example, to determine optimal start-up or load change procedures.

Electrode assembly representation

It is possible to create 1-D, 2-D or 3-D representations of the electrode assembly.

1D, 2-D and 3-D models

1-D model. This is essentially the single-cell model arrangement that is often used for testing. is the 1-D model is appropriate when flow channel conditions can be guaranteed to provide uniform concentration at all points on the anode and cathode surfaces, for example during single-cell testing with an excess of fuel and air.
2-D model.This model is optimized to handle a large number of cells in a computationally efficient manner. The 2 D stacks are typically used in situations where fuel and air flow are co- or counter-current, meaning that there is little significant variation across the depth of the cell.

The use of a 2-D rather than a 3-D model in such situations dramatically reduces the computation time for little or no loss of accuracy.
3-D model. This model is optimized to handle a large number of cells in a computationally efficient manner.. It has one additional dimension (depth) compared to the 2D stack and is typically used in situations where there is significant variation in fuel and air concentration across the anode and cathode surfaces.

This situation typically occurs when fuel and air flow are cross-current or where flow channels involve complex (e.g. serpentine) flow paths.

In the 3-D case the flow channels are often modelled in CFD software such as ANSYS FLUENT ^®. The FLUENT model can be linked to the AML:FC electrode assembly model using the optional AML:FC-FLUENT Hybrid Modelling Interface.

Stack model overview

The following diagram shows the phenomena calculated in each element of a typical electrode assembly and the interactions between the different elements.

The diagram below is for PEM stack. For simplicity the stack in the example only contains one cell that includes the anode and cathode collector plates and the interfaces between cells in a multi-cell stack. An analogous representation exists for SOFC stacks.

Key

	Mass boundary
	Energy boundary
	Electrical boundary

Stack component descriptors

These show the following attributes:

Component
Typical model used
Equations involved / phenomena modelled

Anode collector potential Distributed_resistor_2D Charge balance, potential field		Anode collector Distributed_thermal_conductor_2D Energy balance

		Fuel channel Gas_channel_countercurrent/cocurrent Components continuity, energy balance, momentum balance, thermal/transport properties

Anode potential Distributed_resistor_2D Charge balance, potential field, Ohmic energy generation		Anode Porous_media_2D_anode_gas_liquid components continuity, energy balance , Maxwell-Stefan diffusion, momentum balance, liquid water transport

		Anode Catalyst PEM_catalyst_anode ionic and electronic currents/potentials, waterup-take, ionic conductivity, overpotential, c. continuity, energy balance, M-S diffusion, momentum balance

		Electrolyte PEM_electrolyte_2D ionic potential field, water up-take, ionic conductivity, diffusive transport of water, energy balance, membrane swelling

		Cathode Catalyst PEM_catalyst_cathode ionic and electronic currents/potentials, water up-take, ionic conductivity, overpotential, c. continuity, e. balance, M-S diffusion, m. balance, entropic energy

Cathode potential Distributed_resistor_2D Charge balance, potential field, Ohmic energy generation		Cathode Porous_media_2D_cathode_gas_liquid components continuity, energy balance ,Maxwell-Stefan diffusion, momentum balance, liquid water transport

		Air channel Gas_channel_countercurrent/cocurrent Components continuity, energy balance, momentum balance, thermal/transport properties

Cathode collector potential Distributed_resistor_2D Charge balance, potential field		Cathode collector Distributed_thermal_conductor_2D Energy balance

The AML:FC is provided in two separate versions, SOFC and PEM. These are priced separately.
Contents are as follows:

AML:FC SOFC

AML:FC PEM

PROPERTIES_anode
PROPERTIES_cathode
PROPERTIES_electrolyte
Reforming_Reactions_Stoichiometry
SOFC_Catalyst_anode
SOFC_Catalyst_anode_1D_L
SOFC_Catalyst_cathode
SOFC_Catalyst_cathode_1D_L
SOFC_Electrolyte_1D
SOFC_Electrolyte_2D
SOFC_Multilayer_Membrane_1D
SOFC_Multilayer_Membrane_2D
SOFC_Single_Cell
SOFC_Stack

PROPERTIES_anode
PROPERTIES_cathode
PROPERTIES_electrolyte
Nernst_potential
Nernst_potential_1D_L
Nernst_potential_2D_LW
PEM_Catalyst_1D_anode
PEM_Catalyst_2D_anode
PEM_Catalyst_3D_anode
PEM_Catalyst_1D_cathode
PEM_Catalyst_2D_cathode
PEM_Catalyst_3D_cathode
PEM_Electrolyte_1D
PEM_Electrolyte_2D
PEM_Electrolyte_3D
PEM_Multilayer_Membrane_1D
PEM_Multilayer_Membrane_2D
PEM_Multilayer_Membrane_3D
PEM_Single_Cell
PEM_Stack
PEM_Stack_3D

Both of the above libraries draw on a set of basic and ancillary models common to all types of fuel cell:

AML:FC Channels	AML:FC Basics
Cooling_channel_1D_air Cooling_channel_2D_air Cooling_channel_1D_vaporising_water Cooling_channel_1D_air _crossflow Cooling_channel_2D_air _crossflow Gas_channel_1D_cocurrent Gas_channel_2D_cocurrent Gas_channel_1D_cocurrent_gas_liquid Gas_channel_2D_cocurrent_gas_liquid Gas_channel_1D_countercurrent Gas_channel_2D_countercurrent Gas_channel_1D_countercurrent _gas_liquid Gas_channel_2D_countercurrent _gas_liquid	Base_Component_of_Diffusivity_Coefficient Constants Distributed_Resistor_1D Distributed_Resistor_2D Distributed_Resistor_3D Distributed_Thermal_Conductor_2D Distributed_Thermal_Conductor_3D Fluid_Properties_in_1D_anode Fluid_Properties_in_2D_anode Fluid_Properties_in_3D_anode Fluid_Properties_in_1D_cathode Fluid_Properties_in_2D_cathode Fluid_Properties_in_3D_cathode Porous_Media_1D_anode Porous_Media_2D_anode Porous_Media_3D_anode Porous_Media_1D_anode_reforming Porous_Media_2D_anode_reforming Porous_Media_3D_anode_reforming Porous_Media_1D_anode_gas_liquid Porous_Media_2D_anode_gas_liquid Porous_Media_3D_anode_gas_liquid Porous_Media_1D_cathode Porous_Media_2D_cathode Porous_Media_3D_cathode Porous_Media_1D_cathode_gas_liquid Porous_Media_2D_cathode_gas_liquid Porous_Media_3D_cathode_gas_liquid
AML:FC Reactors
Adiabatic_Bed_Section Catalytic_Bed_1D Catalytic_Bed_Properties Fluid_Properties_1D Simple reformer Simple CO converter Simple tubular after-burner
AML:FC Ancillary
Reservoir Humidifier_Separator Resistor

Physical properties

Any of the physical property options supported by gPROMS can be used within the AML:FC models, providing complete flexibility.