F1technical.net

NL_Fer wrote:What would be the point of starting compression ignition in a prechamber?

The point would be to minimize exposure of the main chamber to the very high compression and combustion pressures and temperatures occurring in the pre-chamber.

NL_Fer wrote:What would be the point of starting compression ignition in a prechamber? I though HCCI was about homogenous burn of the mixturen in the whole combustion chamber.
Thinking further why wouldn't they use Gasoline Stratified Injection Compresssion Ignition. It also has increased compression ratio, increased efficiency and prevent knocking. Look at Hyundai and Delphi's work on GDCI. It looks very usefull for f1 cars.

the point of starting compression ignition in a prechamber ?
to use CI with a fuel with a low Cetane number ie gasoline or (bio)alcohol (or most fuels other than diesel)
though these fuels have a lower BP than diesel, their self-ignition temperature SIT is rather higher
as in F1 fuel rules (min Octane 75)

often called spark-assisted CI
F1 relevant as usefully high mep (not 4 bar as in model aircraft HCCI)
including this http://www.cse.anl.gov/pdfs/2011_hpc_wo ... on_opt.pdf
and see p40 'why gasoline is the best diesel engine fuel'

ringo wrote:

gruntguru wrote:HCCI and Jet-Ignition has come up in several of the engine threads here. Perhaps this thread is the most appropriate in which to focus on combustion?

Here is an update on what might be happening in the Mercedes and other engines.
http://www.motorsportmagazine.com/f1/f1s-power-secret/
The article suggests a combustion pre-chamber which is entered by a protrusion on the piston crown as it approaches TDC.

I don't think the engines are HCCI. They may simply be Jet Ignition combustion. the article seems to be throwing spaghetti at the walls hoping something sticks down the line.

As for low engine speed and part throttle, i think the MGU will manipulate the boost pressure through the compressor to eliminate most of the part load and low engine speed issues.

Mahle have specifically mentioned jet ignition and F1 in several of their press releases

MAHLE Jet Ignition® is a lean burn combustion process, developed by our engineering service provider MAHLE Powertrain for the Formula 1. With substantially greater efficiency, it primarily delivers higher performance in motorsport. This is achieved by means of a special surface ignition of the fuel-air mixture.

The development activities for Ferrari also include innovative combustion processes. For the first time, MAHLE is using a patented solution in this connection that leads to a significant increase in efficiency. The new lean burn combustion process MAHLE Jet Ignition achieves this with a special surface ignition. Higher power output is thus generated for applications in motorsport.

Seems to be a realistic method to achieve engine effiencies around 45%
http://energy.gov/sites/prod/files/2014 ... 2014_o.pdf

godlameroso wrote:The MGU-H can be used in conjunction with the variable trumpets to influence induction timing if you get creative with your cam shaft durations.

You can't control cam phasing, which means you can't easily control the internal EGR rate, which is typically an important control method for HCCI engines.

If the MGU-H is loaded, would this not increase internal EGR due to increased back pressure.

Tommy Cookers wrote:this http://www.cse.anl.gov/pdfs/2011_hpc_wo ... on_opt.pdf

seems to use a -dP (true back pressure) of 0.25 bar throughout
(as did similar engines posted by another poster)

my earlier criticism that such a lean running SI/HCCI engine must in some ways be a 'bigger' engine needs qualifying, because ......

the friction is low relative to a diesel's, presumably because .......
ring friction is less throughout (the dominant design factor, peak pressure, is far lower than a diesel's)
bearing friction is less through for the same reason
the mechanical efficiency is rather high

'dilution' of heat by surplus air lowers temperatures throughout, greatly reducing losses to coolant and exhaust (the turbine-unuseable part)
the surplus air's volume is not 'bigger' as the charge pressure is unusually high
little or no charge cooling is needed
(outside F1 more complex compressors and turbines and higher boosts are possible, and specific heat ratios may then be more favourable)

at partial powers the efficiency will fall with boost reduction and further leaning
so it is far from ideal for road car use, though this would be alleviable by electric hybridisation

TE values are of course gross (of mechanical losses), not overall eficiencies - this basic point may be relevant to the Mercedes PR
the F1 engine will be at the low ie safe/proven end of the potential range described in the source

So it seems Ferrari is using Honeywell for their compressors and turbines.

https://turbo.honeywell.com/whats-new-i ... formula-1/

2 things were stated here, not sure if you can derive much information from either:
1. “When you consider that exhaust gas temperatures approach the temperature of lava, and internal tip speeds for the turbo’s turbine wheel are approaching 600 meters per second, you begin to see the challenges for bringing durability and performance together,” said Craig Balis, vice president and chief technology officer for Honeywell Transportation Systems.
2. "In general, for each percentage point of efficiency gain by the turbine and the compressor wheels, the engine can produce 2kW and 1kW of more power respectively."

Note I'll also post this in the Ferrari PU thread.

Lava is in the range 700°C to 1250. Exhaust gas temperature approaching 700 seems a little lower than has been suggested.

A disc 91 mm diameter has a tip speed approaching 600m/s at 125,000 rpm. ( 114mm @ 100,000)

Mahle's Ferarri F1 "Jet Ignition" PR mentions only "special surface ignition".

The word "spark" doesn't appear.

The word "ignition" only appears as part of the phrase "special surface ignition". http://www.us.mahle.com/mahle_north_ame ... y-life.jsp

What "special surface" does Mahle use to ignite the charge?

gruntguru wrote:HCCI and Jet-Ignition has come up in several of the engine threads here. Perhaps this thread is the most appropriate in which to focus on combustion?

Here is an update on what might be happening in the Mercedes and other engines.
http://www.motorsportmagazine.com/f1/f1s-power-secret/
The article suggests a combustion pre-chamber which is entered by a protrusion on the piston crown as it approaches TDC.

For clarity purposes, what Mr. Hughes described isn't HCCI, (though he labels it as HCCI).

1. Compression ignition occurs in the richer pre-chamber.
2. The pre-chamber then ignites the leaner main chamber.
3. Two different A/F mixtures (by definition) aren't homogeneous.

Not sure what the correct term would be to describe this compression ignition system, but for clarity it seems inappropriate to describe it as HCCI.

What about that?

http://www.f1talks.pl/2016/04/24/techno ... ch-ferrari

According to this article Mahle confirmed in their annual report (published two days ago) that TJI was introduced in Scuderia Ferrari engine.

Vortex Motio wrote: ......For clarity purposes, what Mr. Hughes described isn't HCCI, (though he labels it as HCCI).

1. Compression ignition occurs in the richer pre-chamber.
2. The pre-chamber then ignites the leaner main chamber.
3. Two different A/F mixtures (by definition) aren't homogeneous.

Not sure what the correct term would be to describe this compression ignition system, but for clarity it seems inappropriate to describe it as HCCI.

imo (and having at first had the same view as yours) ....
the convention among researchers seems to regard it as HCCI
presumably because the main charge exists before being ignited ie the opposite of the usual CI injection coinciding with combustion

Besides the confusion for those trying to understand the engine tech of F1, one could suppose that some researchers who working on true HCCI would not be amused by F1 journalists using the term to describe something that isn't truly HCCI.

So there is no HCCI nor CI, if I understand the polish article well. But can we really disclose CI definitely (an f1 angine that works a bit like an indirect injection diesel engine at certain loads)?
The Mahle quotes are a bit vague indeed...

Those Mahle quotes are from marsh.
In april 22nd they wrote

An exciting innovation is currently undergoing its endurance test on the Formula 1 race track. “With MAHLE Jet Ignition, we have developed a solution for Scuderia Ferrari, which uses fuel considerably more efficiently,” Scheider emphasized. Just a few weeks ago, MAHLE once again deepened the technical cooperation of already more than 25 years.

IF it some form of compression ignition, i find it hard to believe it is homogenious. I mean homogenious is good for lowering combustion temps and low NOx, but i think a stratified charge is more efficient.

What puzzles me, for autoignition a low octane number is beter, but how do they prevent knocking?