Ford to Use Eaton Air-Delivery Compressors In Fuel-Cell Program
18 November 2006
Ford Motor Company has selected Eaton Corporation to provide advanced air delivery compressors to the automaker’s FreedomCAR and Fuel Partnership fuel cell demonstration program.
Eaton has been developing engine air management components and systems for passenger vehicles and stationary engine manufacturers for decades. Its expertise includes Roots-type superchargers and by working with the fuel-cell stack manufacturers, its advanced engineering group has successfully applied the supercharger compressor technology to the fuel-cell environment.
Using fuel cells in automobiles presents a unique air delivery challenge. The combination of efficiency, pressure ratio, size, flow rate and cost requires a delicate balance that we’ve achieved through our relationships with multiple fuel-cell stack manufacturers.
—Glenn Gouldey, Vice President, Technology and Planning, Eaton Automotive Group
Eaton now offers additional types of compressors and compressor technologies for various fuel-cell stack sizes and applications.
Stacks do require air flow and these guys know how to do that. But after 10 years of stack development I would think they would have this worked out by now and these components would be off the shelf.
Posted by: SJC | 18 November 2006 at 08:48 AM
Fuel cell stacks are still constrained on rated power and hydrogen is likely to be much more expensive than gasoline, on a per-BTU basis. Therefore, you would want a high-efficiency compressor system. Roots blowers are bulky and not terribly efficient, even with Eaton's new four-vane design. They increase pressure but not density.
A centrifugal compressor might be a better choice, especially in combination with a PEM stack operating at elevated temperatures of 200 degC or so. That way, you can fit both the main radiator and the intercooler in the engine compartment.
Either way, the compressor unit must be powered electrically - a departure from conventional boost systems, albeit one that provides an additional degree of freedom for the powertrain controller.
Posted by: Rafael Seidl | 18 November 2006 at 09:51 AM
One of the advantages to an SOFC is you can use a turbo on the output to drive the input and an alternator. This saves energy and can boost output.
Posted by: SJC | 18 November 2006 at 11:38 AM
Honestly, Rafael, do you even read what you write?
Posted by: Engineer-Poet | 18 November 2006 at 02:52 PM
Engineer-Poet -
you are incorrect. Increasing initial pressure does of course increase specific power, since the whole thermodynamic cycle is executed at higher pressure levels. It's just that when you increase both power and density, specific power goes up by even more.
http://en.wikipedia.org/wiki/Roots_blower
As the diagram indicates, the mechanism does not reduce the volume available to the gas. Roots superchargers feature isobaric efficiencies of about 55%. The advantage is that the pressure boost is available instantly and at virtually any volume flow rate.
For a centrifugal compressor, isentropic efficiency can reach 75% in the optimum operating range, i.e. it's much worse than that for low volume flow rates (corresponding to part load and low RPM in a gasoline engine).
Posted by: Rafael Seidl | 18 November 2006 at 03:13 PM
Rafael:
I believe that air compressor invariable would be followed by intercooler. This way both pressure and density will be higher.
Posted by: Andrey | 19 November 2006 at 01:05 AM
If you meant that a Roots blower doesn't reduce the volume of the gas internally, you should have said so.
The positive-displacement answer to that is the scroll compressor or G-lader.
Posted by: Engineer-Poet | 19 November 2006 at 03:57 AM
Who would want a battery electric car with just a controller, battery, and motor.
Much better to have compressors and fuel cells and hydrogen tanks with management systems and cooling systems and all this plus a brand new refuelling infrastructure.
Posted by: Ender | 19 November 2006 at 04:46 PM
When I see a battery car replace the full utility of an ICE car, then I might think it is possible. When you have 50kwh of batteries that cost $2000 and last 10 years with 1000s of deep recharges and can be fully recharged in 5 minutes for another 400 mile range without using half the communities electricity for that 5 minutes, then maybe...
Posted by: SJC | 19 November 2006 at 05:31 PM
SJC, you're talking about the Altair Nano batteries.
Posted by: Engineer-Poet | 19 November 2006 at 06:46 PM
Just so we know what price a batter needs to be to compete with ICE .... what is the cost of a mid-sized power train?
Posted by: Neil | 19 November 2006 at 07:45 PM
Neil - "Just so we know what price a batter needs to be to compete with ICE"
You cannot really compete with a mature, nearly 100 year old technology like the ICE car with manufacturing volume in the hundreds of millions.
A better price comparison would be aero engines that can cost AUD$10 000 for a 80kW engine.
The new A123 and Alair Nano batteries are pretty much on the money as far as range, recharging and cycle life. The Alair batteries recently completed 15 000 cycles. BTW how long do you suppose it will take to refuel a 10 000 psi tank?
Posted by: Ender | 20 November 2006 at 05:33 AM
I don't think you can recharge 100 cars with 50kwh of energy at the same time in 5 minutes like you can fill 100 tanks with liquid fuel at the same time in 5 minutes.
If you do the calculations, you might find that you would require the entire power consumption of a city of 100,000 people for that 5 minutes.
Posted by: SJC | 20 November 2006 at 03:30 PM
Ah, SJC's goalposts have moved. Before, they were about the limits of the car; now, they're the limits of the electrical network (and what station has 100 pumps?).
Rest assured that this is vanishingly unlikely as such vehicles would best be used. The vehicle batteries are most valuable if the car is plugged in whenever it's not moving; this lets them manage fluctuations in grid load. Accordingly, commuters would either be off-grid or incrementally charging all day rather than all at once.
The "demand burst" scenario is most likely at stations on freeways, where cars would arrive with drained batteries and leave in just a few minutes. One way to meet such demands is with the local folks whose cars are sitting there, plugged in: they sell some stored juice to the grid, the grid re-sells it to the station at a profit, the station marks it up again for the traveller. A thousand cars in driveways and garages could feed the hundred with no difficulty; all it takes is fat wires.
Posted by: Engineer-Poet | 21 November 2006 at 06:49 PM
There are DME developments in China today:
Since DME has an advantage of decomposition at lower temperature than methane and LPG, R&D for hydrogen source for fuel cell has been carried out.
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Posted by: Cheryl Ho | 23 May 2007 at 08:44 PM