Optimum supply and utilization of pure oxygen along with nitrogen on the cathode side for thermal stability of a proton exchange membrane fuel cell

ABSTRACT

As the economical operation of Fuel Cells is essential, in this work, a simulation study is carried out on a 3D geometry of the cathode side of a single-layered Proton Exchange Membrane Fuel Cell (PEMFC) since the cathode reaction is the limiting step. The oxygen and nitrogen mass fraction in the inlet feed on the cathode side are varied as well as the total feed flow rate consisting of traces of water vapor. The worst-case scenario of no-cooling that is with an insulated bipolar plate is assumed. This is to test the maximum thermal effect on the membrane. The flow, heat, and mass transfer multiphysics phenomena in the gas diffusion layer and catalyst scaffold layer are simulated using a simplified geometry and an own program in COMSOL Multiphysics software. The electrochemical reaction of oxygen reacting with hydrogen is considered instantaneous reaction at the catalyst surface. A performance factor comprising of power density generated, the maximum temperature and oxygen utilization is defined. It is optimized for the purpose of determining the optimum oxygen mass fraction in feed and net feed flow rate that gives long life thermally and low operating cost of a PEMFC.

KEYWORDS:

• PEM Fuel cell
• heat and mass transfer
• modeling and simulation
• fuel cell performance
• optimization

Nomenclature

ΔHR	=	Heat of reaction (J/mol)
CP	=	Coefficient of specific heat capacity (J/kg K)
${\mathrm{D}}_{\mathrm{i}}^{\mathrm{F}}$	=	Diffusivity of species i for Fick’s law diffusion (m2/s)
${\mathrm{D}}_{\mathrm{i}}^{\mathrm{T}}$	=	Diffusivity of species i for Soret effect (m2/s)
I	=	Identity matrix (Dimensionless)
ji	=	Mass flux of each species (kg/m2s)
k	=	Thermal conductivity (W/mK)
m1	=	Molecular weight of Oxygen (kg/kmol)
m2	=	Molecular weight of Nitrogen (kg/kmol)
m3	=	Molecular weight of Water Vapor (kg/kmol)
Mavg	=	Average molecular weight (kg/kmol)
Mi	=	Molecular weight of each species (kg/kmol)
Mw,i	=	Molecular weight of each species (kg/kmol)
Ni	=	Total mass flux each species (kg/m2 s)
P	=	Pressure field (Pa)
qw	=	Heat source at catalyst wall surface (W/m2)
R	=	Universal gas constant (8314 J/Kmol K)
Ri	=	Reaction rate of each species in bulk (kg/m3 s)
T	=	Temperature (K)
u	=	Velocity vector field (m/s)
wi	=	Mass fraction of each species (Dimensionless)
xi	=	Mass fraction of species i
yi	=	Mole fraction of species i

Greek & Other Symbols

•	=	Dot product between vectors
∇	=	Gradient or Divergence operator (1/m)
∇2	=	Laplace operator (1/m2)

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Ramakant Gadhewal

Ramakant Gadhewal is a Ph.D. candidate in Chemical Engineering at the National Institute of Technology (NIT), Warangal, India. He has completed his M.Tech from the Indian Institute of Technology (ISM) Dhanbad and B.E. from the Central University (Institute of Technology) Bilaspur. He has 2 years of JRF experience at Central University, Bilaspur and 18 months of SRF experience at the Indian Institute of Technology (IIT) Mandi. Email: [email protected]

Sunil Kumar Thamida

Sunil Kumar Thamida is a PhD holder in Chemical Engineering from the University of Notre Dame, USA. He has completed his M.E. from the Indian Institute of Science (IISc) Bangalore and B.Tech from the Indian Institute of Technology (IIT) Madras. He has 5 years of Industrial R&D experience and 10 years of Teaching experience. His Research experience is in Transport Phenomena, Microfluidics and Corrosion simulations, and he has guided 3 PhD scholars and 8 M.Tech student research projects. Email: [email protected]

Venu Vinod Ananthula

Venu Vinod Ananthula is a PhD holder in Chemical Engineering from the National Institute of Technology Warangal, India. He has completed his M.Tech. from the Indian Institute of Technology (IIT) Kanpur and B.Tech from the National Institute of Technology (NIT) (previously known as Regional Engineering College) Warangal. He has 4 years of Industrial R&D experience and 23 years of Teaching experience. His Research experience is in Heat Transfer enhancement using nanofluids, Fluidized bed bioreactors, Spout-fluid beds and he has guided 4 PhD scholars and 22 M.Tech student research projects. Email: [email protected]