modeling and simulations of multiphysics phenomena and ......division of heat transfer | department...

DIVISION OF HEAT TRANSFER | DEPARTMENT OF ENERGY SCIENCES

Modeling and Simulations of Multiphysics

Phenomena and Performance in Proton

Exchange Membrane Fuel Cells-DEMO

2020 | MVKF25 Hydrogen, Batteries and Fuel CellsSee also Chapter 10 in course book


Outline

(1) Modeling of PEMFCs

(2) Examples


Modeling of PEMFCs

(1) MacroscaleBased on the continuum assumption: FVM, FEM etc.

❖ Numerical methods at three levels?

(2) MesoscaleLattice-Boltzmann method (LBM)

(3) MicroscaleMolecular dynamics simulation (MDS)


Modeling of PEMFCs

❑ In-house codes❑ Commercial softwares

❖Macroscale modeling approaches

• ANSYS-FLUENT• COMSOL Multiphysics• OPEN FOAM (open source code)• ...


Modeling of PEMFCs

ANSYS Fluent is a commercial software for modelingfluid flow and several other related physicalphenomena.

❖What is ANSYS Fluent?

❖ ANSYS Fluent applicationsAerodynamics, heat transfer, combustion, reactingflows, mixtures of liquids/solids/gas, particledispersions, hydrodynamics, and much more.


Modeling of PEMFCs

❖ Numerical simulation procedure


Modeling of PEMFCs

❖ How to model PEMFCs in Fluent

❑ Add-on modules❑Models developed using UDFs

• General CFD code• Additional submodels


Modeling of PEMFCs

❖ ANSYS Fluent fuel cell add-on module


Introduction

❖ How do PEM fuel cells work?

http://www.intelligent-energy.com/technology/technology-faq/ (Animation)

𝑨𝒏𝒐𝒅𝒆:𝐻2 → 2𝐻+ + 2𝑒−

Τ𝑪𝒂𝒕𝒉𝒐𝒅𝒆: 1 2𝑂2 + 2𝐻+ + 2𝑒− → 𝐻2𝑂

𝑶𝒗𝒆𝒓𝒂𝒍𝒍:𝐻2 +𝟏

𝟐𝑂2 → 𝐻2𝑂


Introduction

❖Why do we need PEM fuel cells?• Fuel efficient energy conversion• High power density

• Environmental friendliness

❖ PEM fuel cell applications


Introduction

❖ PEM fuel cell components?

Gas diffusion layer

Catalyst layer

Membrane

Catalyst layer

Gas diffusion layer

Zamel, N., & Li, X. (2013). Progress in Energy and Combustion Science, 39(1), 111-146 (GDL SEM image).Siddique, N. A., & Liu, F. (2010). Acta, 55(19), 5357-5366 (CL SEM image).

Current collector

Current collector


Mathematical Model

❖ Governing equations

• Mass conservation equation

𝛻 ⋅ (𝜌𝑢) = 𝑆𝑚𝑎𝑠𝑠

• Momentum conservation equation

𝛻 ⋅ 𝜌𝑢𝑢 = 𝛻 ∙ 𝜇𝛻𝑢 − 𝛻𝑃 + 𝑆𝑚𝑜𝑚

• Species conservation equation

𝛻 ⋅ 𝜌𝑢𝑌𝑖 = 𝛻 ∙ 𝜌𝐷𝑒𝑓𝑓,𝑖𝛻𝑌𝑖 + 𝑆𝑖

• Energy conservation equation

𝛻 ⋅ 𝜌𝑐𝑝𝑢𝑇 = 𝛻 ∙ 𝑘𝑒𝑓𝑓𝛻T + 𝑆𝑇

• Charge conservation equation

𝛻 ⋅ 𝜎𝑒𝑓𝑓,𝑠𝛻𝜙𝑠 + 𝑆𝑠 = 0

𝛻 ⋅ 𝜎𝑒𝑓𝑓,𝑚𝛻𝜙𝑚 + 𝑆𝑚 = 0


Mathematical Model

❖ Governing equations

• Liquid water transport equation

𝛻 ⋅ 𝜌𝑙𝐾𝑟𝑙𝜇𝑔

𝐾𝑟𝑔𝜇𝑙𝑢 = 𝛻 ∙ 𝜌𝑙𝐷𝑠𝛻𝑠 + 𝑆𝑙

• Dissolved water transport equation

−𝛻 ⋅𝑛𝑑𝐹𝜎𝑚𝛻𝜙𝑚 = 𝛻 ∙

𝜌𝑚𝑀𝑚

𝐷𝜆𝛻𝜆 + 𝑆𝜆


Results - Case 1

❖ Geometry description


Results – Case 1

❖ Cell performance


❖ Pressure

Results - Case 1


Results - Case 1

❖ Oxygen mass fraction


Results - Case 1

❖ Liquid water saturation


Results - Case 1

❖ Local current density


❖ Effect of GDL deformation

1. Zhou, P., Wu, C. W., & Ma, G. J. (2007). Journal of Power Sources, 163(2), 874-881.

2. Nitta, I., Karvonen, S., Himanen, O., & Mikkola, M. (2008). Fuel Cells, 8(6), 410-421.

Results - Case 2


Results - Case 2

❖ Local thickness and porosity


Results - Case 2



Results - Case 2

❖ Oxygen concentration


Results - Case 2

❖ Temperature distribution


Results - Case 2

❖ Liquid water saturation


Results - Case 2



Results - Case 3

Case A Case B

❖ Schematic of the HT-PEMFCs


Results - Case 3



Results - Case 3


443 443.2 443.4 443.6 443.8 444 444.2 444.4

443 443.2 443.4 443.6 443.8 444 444.2 444.4

444.4

444.2

444

443.8

443.6

443.4

443.2

443

Case A Case B


Results - Case 3



Results - Case 4

❖ Geometry description


Results - Case 4



Summary

❖ The PEM fuel cell working

http://www.intelligent-energy.com/technology/technology-faq/ (Animation)

𝑨𝒏𝒐𝒅𝒆:𝐻2 → 2𝐻+ + 2𝑒−

Τ𝑪𝒂𝒕𝒉𝒐𝒅𝒆: 1 2𝑂2 + 2𝐻+ + 2𝑒− → 𝐻2𝑂

𝑶𝒗𝒆𝒓𝒂𝒍𝒍:𝐻2 +𝟏

𝟐𝑂2 → 𝐻2𝑂

modeling and simulations of multiphysics phenomena and ......division of heat transfer | department...

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