akshaya jena and krishna gupta porous materials, inc. ny, usa fuel cells r&d enhancing...
TRANSCRIPT
Akshaya Jena and Krishna Gupta
Porous Materials, Inc.NY, USA
Fuel Cells R&DEnhancing Performance through Pore
Structure
Dependence of Performance of Fuel Cells on Pore Structure of its Components
Many fuel cell porous components Examples: Membranes, GDLs, Separators, Electrodes
Pore structure governs fluid flowPore structure influences kinetics of physico-
chemical processes occurring in fuel cellsPore structure characteristics are critical
factors that determine performance of fuel cells
Dependence of Performance of Fuel Cells
on Pore Structure of its Components
Important and relevant pore structure characteristics, which need to be determined: Pore diameter Pore throat diameter Pore volume Pore distribution Graded pore structure Surface area External surface area Total porosity Hydrophobic and hydrophilic nature of pores in a
mixture Liquid and gas permeability Diffusional flow
Influence of working environment on pore structure needs to be determined Chemical environment Operating temperature Humidity Stress generated during operation
Dependence of Performance of Fuel Cells
on Pore Structure of its Components
Many techniques are available for evaluation of pore structure characteristics of fuel cell components:
Capillary Flow Porometry Measures:
Wide range of through pore throat diameters Pore distribution Gas permeability Structure over a range of:
Temperature Stress Chemical environment Controlled humidity
Techniques for Measurement of Pore Structure Characteristics
Techniques for Measurement of Pore Structure Characteristics
Liquid Extrusion Porosimetry Measures:
Through pore volume Through pore diameters Pore distribution Hydrophobic pores Hydrophilic pores Structure over a range of:
TemperatureStressChemical environmentControlled humidity
Capillary Condensation Flow Porometry Measures:
Through nanopore diameter Distribution Flow rate Without structural distortion (Negligible pressure, Ambient
temperature)Permeametry
Measures: Gas, vapor, and liquid transmission rates Many chemical species Over a wide range of temperature, pressure, and
concentration
Techniques for Measurement of Pore Structure Characteristics
Vacuapore Measures:
Through and blind hydrophobic pore volume Pore diameter Pore distribution
Mercury Intrusion Porosimetry Measures:
Through and blind pore volume Pore diameter Pore distribution
Techniques for Measurement of Pore Structure Characteristics
BET Sorptometry Measures:
Surface area Very small through and blind pore volume Distribution Chemisorptions of many chemicals over a wide range of
temperature and pressure
Pycnometry Measures:
True and bulk density
Techniques for Measurement of Pore Structure Characteristics
About PMI Porous Materials, Inc. designs, manufactures, and
sells instruments for pore structure characterization Has vast experience in patenting of novel technology
for pore structure characterization and developing custom instruments for a wide variety of applications
Has published many papers and presented many oral and poster papers in conferences on pore structure, characterization of fuel cells, and battery components
Has supplied instruments to many fuel cell and battery related industries and research laboratories all over the globe
How Can PMI Help?
Pore Structure Characterization Instruments by PMI
PMI Fuel Cell Porometer
and Advanced Capillary Flow Porometer
Specially designed for fuel cell components
Other unique instruments
Liquid Extrusion Porosimeter
and Vacuapore
Pore Structure Characterization Instruments by PMI
Click here to download a full
PDF on this subject.
Pore Structure Characterization Instruments by PMI
The Capillary Condensation Flow Porometer
Specifically designed for
membranes with fine pores.
Pore Structure Characterization Instruments by PMI
All the instruments needed for pore
structure characterization of fuel
cell components are manufactured by PMI.
Fully automated: Test execution Data acquisition Data storage Data reduction
Windows-based menu driven simple operation
Objective, accurate, and reproducible results
The Fully Automated Instruments
PMI In-House Contract Testing Laboratory
We test fuel cell components of many customers from all over the globe.
Test time can be as low as two days.
What is Toray Paper? A carbon coated material extensively used in the fuel
cell industryVolume of Different Kinds of Pores
Different functions of fuel cell components are governed by different kinds of pores
PMI instruments used to measure pore volumes Volume of the through pores:
PMI Liquid Extrusion Porosimeter Volume of through and blind pores:
PMI Mercury Intrusion Porosimeter Volume of through and blind hydrophobic pores:
PMI Vacuapore
Example of Application of PMI Instruments:
Pore Structure Characterization of Toray Paper
Measured Pore Volume
Through Pores:
75% of the pore volume
Blind Pores:
25% of the pore volume
Hydrophobic Pores:
29% of pore volume
Hydrophilic Pores:
71% of pore volume Click here to download a full PDF on this subject.
Pore volume distribution given as distribution function
Differences between peaks used to estimate distribution of blind pores and hydrophilic pores
Pore Volume Distribution of Different Kinds of Pores
Pore Volume Distribution of Different
Kinds of Pores
Median pore diameters of various kinds of pores are shown in the table on the
following slide.Click here to download a PDF on the subject.
Characteristics
Through Pores
Blind Pores Hydrophobic Pores
Hydrophilic Pores
% of Pore Volume
75% 25% 29% 71%
Median Pore Diameter
60 m 40 m 35 m 50 m
Kind of Pore Hydrophilic
Hydrophobic
Blind Pores Through Pores
Median Pore Diameters of Various Pores
Through pores primarily hydrophilic
Blind pores primarily hydrophobic
Hydrophilic through pores also measurable by PMI Water Extrusion Porosimeter
Pore throat diameters determine Flow rate of fluid through the through pores Restrictions for passage of large particles through the
through pores Through pore throat diameters measurable by:
PMI Capillary Flow Porometer
Characteristics of Through Pores Responsible for Fluid Flow
Characteristics Values
The Largest Throat Diameter 50.43 m
Mean Flow Throat Diameter 32.48 m
Range of Throat Diameters 20 – 45 m
Change of Pore Diameter Along Pore Length
Small
Median Pore Diameter based on Volume
60 m
Volume of Pores 75%
Nature of Pores Hydrophilic
Pore Throat Characteristics of Through Pores
Distribution of Pore Throat Diameters
Most of the through pore throat diameters are in the range of 20-45 m
Comparison of Pore Throat Diameters and Volume Based Pore
Diameters
Comparison with volume based values suggests that shapes of through pores are not like hour glasses
Through pore diameters do not change appreciably along the pore length and are similar in magnitude
Click here to download a PDF on the subject.
You can visit our website to see the wide spectrum of pore structure capability that our instruments offer
If you have a special need that is not part of PMI’s standard test list, the engineers at PMI will be happy to talk to you about your testing requirements and come up with a suitable solution.
Special Needs
Have a nice day!
Thank you!