25-08-2017, 09:32 PM
Laminar Flow (Membraneless) Fuel cells (LFFC’s)
Laminar Flow (Membraneless).pptx (Size: 916.95 KB / Downloads: 67)
Overview
The first fuel cell was developed by Sir Robert Grove (1839)
Modern fuel cell
Two types (PEMFC and SOFC)
Why use fuel cells?
Alternative to batteries
Li-Ion- 250-360 Wh/L
Hydrogen - 2800 Wh/L
Borohydride - 2200 Wh/L
Methanol - 4416 Wh/L
Environmental concerns
Generally cleaner (H/C ratio)
Coal – .5-1.0
Ethanol – 3.0
Sodium Borohydride – 4.0
Methane, Methanol- 4.0
Hydrogen – Inf
Disadvantages of current fuel cells
PEMFC
Low Temperature
Expensive catalysts (Platinum/Palladium/Ruthenium)
Expensive Membrane (Nafion $15/cm^2-low loading)
MEA can account for 50% cost
SOFC
High Temperature
No catalysts required
Can run on butane, methane etc.
Cross Over
Diffusion of reactants at anode and cathode can be rate limiting
Hydrogen/Oxygen cells bulky due to hydrogen storage issues
Laminar Flow Fuel Cells
Direct Methanol Fuel cells
High Crossover/Low Efficiency
Very common fuel for FC’s
LFFC’s
Diffusion Based
Reynolds Number = .01
Still have some issues with crossover
Other Fuels/Self Pumping
Ancillary Mechanisms needed (eg. Pump)
Can make system complex and expensive
Formic acid/Sulfuric acid also widely researched
Self Pumping Mechanism
UCLA and MTU
APPLICATIONS
Portable power (cell phones, laptops etc.)
INI Power Systems, of North Carolina (www.inipower.com), says it delivered a beta 15W system to a military customer in August and signed a joint development agreement with a major Asian battery and laptop OEM to integrate its stacks into a consumer platform. It is also working on a telecommunications power supply with partner Advanced Power Systems, targeted for the first half of 2008. Anthony Atti, VP of business development, reports the military test unit is running more than nine hours on 200cc of neat methanol, and a 72-hour military mission would require total system and fuel weight of less than 9lb.