Thermoelectric-Powered Hydrogen Injection System
21 August 2006
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| The basic design of the TEG-Electrolyzer system |
Hi-Z Technology and Dynamic Fuel Systems are exploring the use of electricity generated from waste heat to power an on-board electrolysis unit to produce hydrogen for supplementary injection into the intake port of an engine to increase combustion efficiency.
Hi-Z is a developer of thermoelectric waste heat recovery systems (earlier post) and Dynamic Fuel Systems is the developer of the on-board electrolysis unit.
The 180-watt thermoelectric generator (TEG) used in the project was the original proof-of-principle generator Hi-Z used for its 1 kW TEG later developed.
The Jetstar hydrogen generation unit normally draws power from the vehicle’s electrical system. Use of the TEG generator reduces the parasitic load, further enhancing fuel economy. John Bass of Hi-Z presented the concept in a poster session at the Diesel Engine-Efficiency and Emissions Research Conference (DEER) 2006.
Supplemental hydrogen injection into the intake of engines can improve fuel efficiency while reducing emissions. (Earlier post.)
This system will likely make diesels cleaner. Since it also takes energy from exhaust heat (preferably post- catalytic treatment) it improves the efficiency of the vehicle.
Posted by: allen Z | 21 August 2006 at 06:27 PM
I have thought that a steam turbine to recover waste heat would be good with a hybrid, but at only 10% efficiency it was not worth it. If the hydrogen and oxygen help, this might make it more cost effective.
Posted by: SJC | 21 August 2006 at 09:08 PM
"I have thought that a steam turbine to recover waste heat would be good with a hybrid, but at only 10% efficiency it was not worth it."
I thought BMW's Turbosteamer claimed to recover over 80% of the waste heat?
Posted by: Angelo | 22 August 2006 at 03:23 AM
It is one thing to recover heat but another thing to put it to good use. Diesels have a lower exhaust gas temp that gasoline burners which lowers the Carnot efficiency.
Posted by: tom deplume | 22 August 2006 at 06:03 AM
That is the case. You can recover lots of heat, but having enough high grade heat to get efficient conversion to mechanical or electrical power is another matter.
Posted by: SJC | 22 August 2006 at 10:23 AM
Whar is the feedwater source? Exhaust condensate?
Posted by: richard schumacher | 23 August 2006 at 03:10 AM
I assume you are asking about the BMW project. You would have to look at past articles to see. Just search this site for turbosteamer.
http://www.greencarcongress.com/2005/12/bmw_developing_.html
Posted by: SJC | 23 August 2006 at 08:52 AM
Angelo:
80% efficiency is near impossible. The highly optimized modern steam turbines you find in electric power plants can hardly manage an efficiency of 60%.
Posted by: anne | 23 August 2006 at 08:54 AM
From the BMW article:
The primary energy supplier is the high-temperature circuit which uses exhaust heat from the internal combustion engine as an energy source via heat exchangers. More than 80% of the heat energy contained in the exhaust gases is recycled using this technology, according to BMW.
30% of the heat goes out the cooling system and 40% goes out the exhaust. Getting 80% recovered from the exahust is good but the expander only adds 14hp and 15% better fuel economy.
As far as where these guys get the water, you can have a quart container you fill once a month. They are only generating 1kw of hydrogen.
Posted by: SJC | 23 August 2006 at 06:23 PM
Sounds really cheap, not. Waste through a Peltier device to make electricity to drive an electrolyser to make hydrogen to inject into the intake port!
Do you have any idea how little hydrogen can be made with 180W and how little effect it will have on emissions?
There have got to be a lot better uses for a TEG that actually works - http://www.greencarcongress.com/2005/07/thermoelectrics.html
Posted by: drmartin | 24 August 2006 at 06:35 PM
One way I look at recovering heat and creating power is, what would it take to make a 20% efficient I.C.E. 25% efficient versus turning 50% of the waste heat into a 10% efficient power producer? Thermal electrics are not 10% efficient, vapor turbines might be and the turbosteamer from BMW generates 14 hp and uses 15% less fuel.
It comes down to cost effective. You would want something simple, reliable and inexpensive to recover at least some of that waste heat. Or, just tackle the waste in the fist place with a simple, reliable and affordable 35% efficient PEM fuel cell. Or better yet, use an SOFC and cogenerate with a turbine on the output and get 50% efficiency. SOFCs can pretty much run on NG right out of the pipe with very little processing and could power your home in a sort of reverse plug hybrid distributed generation configuration.
Posted by: SJC | 24 August 2006 at 09:04 PM
DEvelopments in DME 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. DME has a potential of feedstock for chemicals. DME to olefins is under development in Japan.
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Posted by: Robert | 27 July 2007 at 11:41 AM
A better use for a TEG that actually works? How about one that harvests heat from the electrolytic action of a hydrogen fuel cell. Just a guess, but this would be a one hundred percent green application.
Posted by: Glen Monahan | 29 June 2008 at 09:29 AM