Fuel Cell Humidification Using Nafion Moisture Exchange Devices

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Fuel Cell Humidification Using Nafion Moisture
Exchange Devices
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Company History

• Founder worked at DuPont when Nafion was
• developed as an ionomer for electrolysis
  membranes for production of chlorine and alkali
• DuPont elected not to pursue development of
• business exploiting water permeation properties
• Founder left DuPont, started Perma Pure (PPI) in
  
• 1972 to produce Nafion dryers and humidifiers
• Subsequently purchased exclusive license to
• produce Nafion tubing from DuPont

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Company History (continued)

• Founder patented dryer and humidifier designs,
• built business supplying to OEM customers
• Markets are instrumentation for medical, process
• control, environmental monitoring and laboratory
• Medical market is largest segment PPI produces
• ca. 1,000,000 dryers per year for breath analysis
• In 1992, founder retired, sold business to Halma
  
• plc present management in place since then.

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Company History (continued)

• Halma plc is 106 years old, owns 57 companies
• very successful with high capital reserves
• After purchase, PPI expanded into process
• applications, including fuel cells
• PPI business is global, with 51 export sales
• PPI supplied humidifiers for fuel cells for
  years
• PPI sponsored winning fuel cell-powered car in
  1999 Tour de Sol, using PPI humidifier

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Gas Dryer and Humidification Technology
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Nafion Chemical Structure
(CF2 CF2 )m CF CF2 n
O
CF2
CF CF3
Z
O
WHEN m 5 to 13.5 n ca 1,000 z 1,2,3... x
1 to 13
CF2
CF2
.
SO3H H2OX
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Selectivity

• Permeation selectivity is based on chemical
• reactivity, not size
• Only compounds that chemically associate with
• sulfonic acid permeate
• Bases associate with sulfonic acid and permeate
• through membrane wall
• Very few bases are gases at typical operating
• temperatures, so very few compounds permeate

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Why use Nafion as the moisture exchange membrane
in fuel cell humidifiers?

• Nafion transfers moisture quickly
• Water transfers through Nafion as a first order
  kinetic reaction
• Water transport is driven by partial vapor
  pressure differential
• Small device provides high performance
• Nafion transfers water selectively
• Water associates readily with sulfonic acid
  groups and permeates through the membrane wall
• Permeation selectivity is based on chemical
  reactivity with sulfonic acid, not size
• No crossover of any other components besides
  water
• Nafion protects expensive fuel cell components
• Impurities that would poison fuel cell membranes
  will be trapped in humidifier
• Humidifier acts as final scrubber before fuel
  cell stack

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Perma Pures Nafion-based humidifiers for fuel
cells

• Used to humidify hydrogen or air
• Humidifiers available to handle gas flow from
  under 1 lpm up to 4,000 lpm
• Recent advances including development of a molded
  housing have reduced costs by more than 50 in
  some devices

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Perma Pures humidifiers are passive devices

• No moving parts
• No parts to break, wear out, maintain, or control
• No energy required to operate
• Will not be a drain on your system
• No controls needed
• Self limiting operation means water transfer will
  never exceed saturation

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Heat and Moisture Exchange Diagram
Perma Pure humidifiers consist of a bundle of
Nafion tubes, arranged much as a shell and tube
heat exchanger. The inlet gases to be humidified
typically flow through the bundle of tubes, and
the cathode exhaust or heated de-ionized water
surrounds the tubes, providing the source of heat
and moisture.
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Gas to Gas Humidifiers Cathode exhaust stream
flows in shell, Inlet gas flows through tubing

• Most efficient method of humidification available
• Can achieve high degree of water transfer (over
  85 of water content)
• No energy required
• Humidifiers available to handle wide range of
  flows (lt 1 lpm up to 4,000 lpm), temperatures (up
  to 130 C) and pressures (up to 4 bar)
• New low cost model available with molded shell
  and fittings

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Performance of gas to gas humidifiers
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Gas to gas humidifiers offer low pressure drop
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Partial product line of gas to gas
humidifiersNOTE FC300 style now with low cost
molded components
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Liquid to Gas Humidifiers Water flows in shell,
gas flows through tubing

• Variable performance can be achieved by
  regulating temperature of water surrounding
  Nafion tubing
• Typically used for test bench applications where
  variable humidity is required, or to humidify
  hydrogen
• Can achieve high degree of humidity (up to 99
  RH)
• Water requirements
• Heated
• De-ionized
• Circulated
• Cooling water can be used if quality is
  appropriate

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FC 300 gas to gas humidifierNEW Molded ABS
shell and fittings for low cost
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FC 400 gas to gas humidifier
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FC 400 gas to gas humidifier
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Humidifier Development

• Development projects underway
• Performance improvements of membrane
• Optimize tube geometry
• Packaging developments to meet customer needs
• Custom shapes and configurations to meet
  packaging requirements
• Molded housings to reduce costs in commercialized
  projects
• Investigation of new materials and manufacturing
  methods
• Improve temperature and pressure tolerance
• Reduce Costs

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Outlook

• Commercialized in several major projects and
  working with most of the leaders in the industry,
  Perma Pure is meeting todays fuel cell
  humidification requirements.
• With over 30 years of experience designing and
  building moisture exchange devices, we believe we
  will be able to provide the cost effective
  humidification solutions required by the industry
  tomorrow.