Hey, guys. I need your help and advice on something.

Me and my guide were planning to pursue a research paper on the HCCI engine (Homogeneous Charge Compression Ignition), which was supposed to be an experimental paper.

The problem is we are unable to find the testing rig in the country itself.

So now, we are planning on pursuing different alternatives.

One of them is using Matlab for analysis, simulating the engine conditions and obtaining results.

Other is modifying the diesel engine and using it to perform as the HCCI engine.

What do you guys think? Any suggestions? Any other ideas?

Modify an engine, sure. At least, this will tell you what the real difficulties are: stability during the transients, destruction... while a simulation only tells sometimes sensible answers to already known questions.

 

I didn't find o the Web explanations about elementary questions

https://en.wikipedia.org/wiki/Homogeneous_charge_compression_ignition

http://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/hcci.html

they just tell "fantastic progress towards the future with many advantages" BUT:

 

Compressing the premixed air+fuel to ignition means that it ignites before the highest piston position. This is exactly what Otto engines try very hard to avoid since it destructs them. Diesel engines go the other way by injecting the fuel later. Why should an Hcci engine survive?

 

Can the engine run slowly? If ignition occurs at some compression ratio, slow pace gives the combustion plenty of time to stall the engine.

 

The fuel has a rather constant autoignition temperature, but the outer air not. How do you act on the temperature after compression? Wiki suggests the intake valve closes late.

 

Or is the engine built differently? Model plane two-stroke semi-Diesel have a glow plug and compress the mixture a different way. This wouldn't be autoignition. While the maximum compression ratio is less good, at least it works.

Edited August 17, 201510 yr by Enthalpy

Conventional gasoline engines ( Otto cycle ) fire the plug before top dead centre. This is usually built in as an initial timing, plus a variable timing addition depending on rpm and load ( the old mechanical method used centrifugal weights under the distributor cap to vary the timing ).

This is done because the flame front takes a certain amount of time to spread from the ignition plug through the combustion chamber.

Engines with too much initial timing need an 'explosion' modifier to reduce pre-ignition that can 'blow' holes in the piston tops. This is usually done by adding an octane booster, like t-e-lead in the old days, or up to 20% ethanol these days.

 

An HCCL engine may get around this problem of timing advance, because the flame front isn't localised, rather the whole combustion chamber ignites at a certain pressure.

 

( I was a bit of a gear head in my 20s and liked building/modifying engines )

Edited August 19, 201510 yr by MigL