Hydrogen requirements for an ICE.

[Kozy]

Right, before you start, this is NOT another one of those 'oh look, says 'ere I can run my car on water' posts, I know the laws of physics deem this impossible and it is a complete scam.

What I am asking instead is the fuelling requirements of a traditional petrol engine when running on pure hydrogen? I would hazard a guess at it being something like LPG, i.e. around 60% increase in specific fuel consumption?

I do not know the properties with regards to energy content etc of hydrogen as a fuel compared to petrol to make an educted guess.

Anyone know a bit more than myself care to share their thoughts?

[Ferrer]

I guess you could always ask BMW.

Other than that no idea. Altough I'm too interested in learning about hydrogen powered ICEs.

[Alastor]

I do not know the properties with regards to energy content etc of hydrogen as a fuel compared to petrol to make an educted guess.

The Wiki knows all: Heating Value

That is a start anyway...

[drakkie]

I'll try and make a few calculus examples today, ok. I can't be sure it is 100% right, because i only learned them for petrol&diesel though IIRC though from the BMW engine, it delivers about 60% of the power that the petrol version did.

edit: Sorry time shortages yesterday, diving into my library today

[drakkie]

Ok the result of some research in the books:

First up i recommend the Vieweg Handbuch Kraftfahrzeugtechnik, fourth printing, page 324 and onward. ISBN nr: 3-528-33114-3

It has many information on Hydrogen and use in ICE. I'll write a small excerpt/translation for you.

Attachment 1 has some values in comparison to other fuels. From top to bottom; Lower heating value in kWs/g, Self combustion temperature in degree Celsius, Flame temperature in degree Celsius, ignition limits in air in %, maximum ignition energy in mWs, burn speed in air (stoichiometric mixture) in cm/s, detonation limits in %, detonation speed in km/s, theoretical explosion energy in kg TNT/m^3 gas and diffusion coefficient in air in cm/s.

Attachment 2 states the CO2 emissions against the energy gained from it, in well-to-wheel point of view.

Attachment 3 translated:

The hydrogen engine development could in the past 30 years make large progress, starting with the works of Erren and Oehmichen as well as through the research done by BMW and other manufacturers. With that the otto-engine has shown large potential for Automobile uses. For this mostly otto-4-stroke engines with gas-form fuel were developed, but also H2 2-stroke and Wankel-engines.
H2 IC-engines could be based on the basic shape of the petrol version. They use a different form of mixture creation to build a proper, useable mixture (see image on bottom of page). The specific performance density rose significantly by different mixture building and turbo/super-charging.
For example BMW's 12-cylinder engine, that has a different mixture building system, shows typical H2-developments:
- Development of H2-burn cycles
- Changes to electrics and ignition
- Developments in H2-engine controls systems(ECU) including H2-specific developments and side-parts
- Integratrion of H2-rail and H2-injectors in intake
- Modification of valve seats and optimisation of pistons

Burn space geometry and ignition are meant for both H2 and petrol; The engine is meant for two different fuels. In petrol runnings the engine works as it would normally with DI, however in H2-mode the mixture is created externally before injection. These engines make a customer friendly car possible while there are not enough hydrogen gas stations.

4.3.5.1. H2-burn with external fuel mixture.

The mixture building of H2 and air takes places in the intake in the external injection (note: i think they mean like single point injection). Maximal performances are achieved this way in the Labda=1 region.

Attachment 4 translated:

The properties of hydrogen; wide ignition limits, low ignition energies as well as the high flame speeds of H2/air-mixtures increase the chance of uncontrolled and unwanted combustion(after and before normal ignition point) and are responsible for the fact that the running at Labda=1 is a major challenge in development. Here most attention is paid to the thermical stability and on the special burn cycle.

The avoiding of exhaust emissions gives another challenge besides offcourse the achieving of maximum performance. In H2-burn the only relevant emission is that of NOx gas. From the burn of oil the other emissions in the form of CO and HC emerge that are reduced to virtually zero in the three-way-catalyser both in lean as in Labda=1 run.

The forming of NOx depends of the burn temperature. Lean homogenous Hydrogen-air mixture(Labda>>1) burn at lower temperatures, very good efficiency and low NOx, whereby homogenous Hydrogen/Air mixtures burn also stabile at Labda = 4. Because of that the engine can be used in a wide range.

At increasing loads (Labda < 2) the emissions rise substantially and reach their maximum at 1,1 < labda < 1,2 . Also at labda = 1 the emissions also reach a high level. Contrary to use with labda > 1 these emissions can be reduced to a low level by a 3-way cat.

The usage strategy for an unblown engine with external mixture building is defined by the limited ignition limits of H2 as well as by the NOx creation. For a wide use the engine is quality controlled lean mixture burning. The consequences are barely any NOx emissions. In range of 2,0 < labda < 2,2 the engine control unit automatically shifts to labda = 1 range and quantity-control for maximum performances. Mixtures in the range of 1,0 < labda < 2,0 are excluded because of that. With the thereby achieved usage strategy also very low NOx emissions are guaranteed in the entire range and the compliance to all worldwide emission laws is guaranteed.

At external mixture building the mixture burn value can be increased significantly by turbo/super-charging. At charging of 0,85 bar indicative average pressures of 18 bar can be ranged. The maximal reachable density lies at éta = 11 and is limited by early-ignitions in stoichiometric range under full load.


The rest will follow later, i hope it is of value to you guys

edit:
I just had a teacher on the phone for other matters, he has about 450 pages of information on it in German.. If you like i might be able to post, however im not gonna translate all that !

[Kozy]

Wow! I wasn't expecting an answer like that! Very useful, I would be interested in reading a bit more into it, although my German isn't very good!

I'll have to get my head around this bit first mind, bit more involved than I had anticipated.

Many thanks for sharing!

[honda99]

Hi
Your car will never run on water.
But an efficient hydrogen gas generator can help with Fuel Consumption.
You can read more abut it on :
hydrogen gas generator for internal combustion engine ?(gashydrogen)?
Have fun!