Try the "common rail" it is a very challenging part of the engine since the efficiency depends on the droplets and those depend on the pressure and nozzle command.

It rather depends on what facilities you have at your disposal.

I don't know much about diesels, but I'd have thought duration of injection may be interesting... how can the ignition flame front (if that's the right term?) can be affected by injecting faster or slower, or multiple injectors or several short bursts of injection?

I dunno...ask yourself what bit of a diesel interests you most..then ask why it is designed the way it is and can you improve it?

Del

Common rail direct fuel injection is changing diesel engines. I find it very interesting as a consumer. You could study the common rail technology being utilized in Mercedes Benz and SMART suprex engines that meet stringent emissions standards.

Or you could look at proposed aircraft diesel technology like centurion engines by thielert, and maybe figure out what technology is behing investigated by aerohawk, zoche, diesel air limited engines. Or you could study biodiesel conversion in older volkswagen and mercedes diesels.

It is not hard to find interesting subjects on the cutting edge of diesel technology.

I think there is a crying need for simpler emission control for diesels -- no urea tanks to refill, no particulate filters to replace.

I'll agree to that!

The best emission control is perfect combustion; all else are patches.

What about using the waste exhaust heat (as there is no cat converter to keep warm) in an absorbtion chiller to provide aircon?

Or pre-heating the fuel using exhaust heat to improve engine efficiency?

Very topical and increasingly controversial, the use of bio diesel and how to optimise the performance on this fuel?

Hot fuel = reduced power

The diesel engine will run it's best in a snow covered field with NO exhaust backpressure. It's all about filling the cylinders with the maximum qty of air, hence the use of compressors of various types.

Likewise the fuel. The denser the fuel the more energy it is able to transmit to the working fluid (air). Cool it, don't heat it.

Therefore, maximum air charge plus maximum calculated fuel charge equals maximum gas pressure in the cylinders, gives maximum torque. the horsepower is calculated from this, over unit time.

Some mixes of biodiesel are heated only to the point of making them fluid enough to be handled by pumps and filters. Example= Coconut oil gels solid at 25degC. Difficult to pump.

I apologise that this is only the beginning, and in the simplest form, of a very complex issue.

Good luck, fair winds,

Cheers

S.

Dear Student Maverick2012,

We could try mixing a number of cheaper combustibles along with the diesel oil fuel. Years ago (around 1977-as the GM of a small diesel engine manufacturer), I had tried injecting acetylene (from Calcium carbide and water mix) into the spray nozzle and found overall reduction in SFC but the engine ran at a higher temperature resulting in higher lube oil consumption and the engine needed decarb earlier than normal.

I have been toying with the idea of injecting distilled water and acetylene along with the diesel to bring down the fuel cost and operating temperature.The water is expected to become superheated steam and provide a working medium of higher density.

All these would require a co-operative HOD and IC engine lab assistants along with a good jobbing workshop willing to take up one-off pieces of work, besides total dedication on your part-coping with course work!

You may visit my website www.artecrobotics.com to get an idea of my background.Todate, I have successfully guided over 30 UG/PG/PhD projects, mostly in South India (AP,KA,TN,KL).

The water is expected to become superheated steam and provide a working medium of higher density.

If the molecular weight of H20 is 10 and that of N2 is 14, then shouldn't water injection (if injected into the cylinder at the time of fuel injection) provide a lower density working medium? Or are you saying that the cooling effect of water would increase charge density? I'd think that once the valves are closed and compression has occurred, then water injection would reduce combustion temperature and pressure, and therefore torque.

Thank you Ken.I forgot to mention that water would be introduced via a "pre-atomiser" to coincide with the fuel injection and a certain amount of experimentation is called for (through the project work) to establish the quantum of water, injection pressures etc. Basically, the ignition of the diesel fuel is initiated a little ahead of TDC and the combustion propagation has a certain momentum (increasing).The project should be able to establish a family of performance curves and enable a comparative study and analysis to extract the OPTIMALITY of "Timing", "Water" quantity and a certain extent of "Preheat", "Pump pressure" and such like.

The temperature in the cylinder on compression is far higher than the requirement of combusting the diesel oil and you are right about the cooling effect of water, but it is not "Chilling" but relative cooling (Pretty hot-near super heat for water). This will enable an added thrust due to expanding steam on the piston head in addtion to what the products of combustion contribute.

Presently, I am working on a "Trapezoidal" combustion cycle (a substantial improvement over the "Sinusoidal" gas pressure variation)- an invention (patented) by one of my professional associates and are on the verge of building up a new engine for experimentation from Government funding. Both of us are self-employed Design engineers operating independently and collaborating sometimes.

Serge the german Patent office for the diesel water mix system . Two days ago I saw a movie from the inventor showing how the system works. First he started the engine with normal diesel fuel and put a white cloth filter in the exhaust pipe. As expected it came out black. Next he flipped a switch and water was mixed with the diesel oil and created sort of a milky liquid and put a new cloth in the exhaust pipe . Don't know exactly how the power monitor was hooked up but it went to a higher number and the cloth had no black speck on it. The fuel savings would also be substantial.

Why haven't automakers used this patent idea ? the german government hasn't tested and approved it after two years.

Dear Johann Vondrus,

please accept my heartfelt thanks for the information.I was not aware of this and thought I was alone on this line of thought.Now that it is not so stupid idea to introduce water into the combustion zone, I am emboldened to go for a total water atomised spray near TDC and get the adiabatic compression heat to convert the preheated water injection into superheated steam.May be a high density spark can add a boost to the process of generating superheated steam and get a substantially boosted down stroke (Power stroke). At best, we can try low cost gas like C₂H₂ for a further boost.

In fact in the year 1960, I got admissions in "Machinenbau" atTechiche Hochschulen like Munich,Stuttgart, Karlsruhe and a couple of others, immediately after finishing my Junior college studies, specifically because I wanted to work on an invention of mine to clean up the exhaust gases from our buses in India. I had to abandon these because we could not get foreign exchange released for more than a total of US$ 8/-for a three year course in engineering!! So you can see how much time has been lost.Now, I am past 67 years of age and am still at it.Never say "Give up".

I am also surprised that such a demonstration of technology of water mixing has not been taken up in Germany of today-a truly developed country, very wonderfully fastidious in all it does.

Danke schÖnen! Viel danken.

sincerely,

D.Ramakrishna Naidu

You might want to take a new look at an old stationary engine method.

In the gasfields, they were running 2 fuels, delivered separately: natural gas delivered with the air at just below the lean limit of combustion, & then inject a small volume of diesel fuel ("pilot oil") to tip the balance.

The cooling effect of an alchol fuel (substitute for the natural gas) should limit peak temperatures; the source of NOx, eliminating the need for an EGR system.

i also believe that the pre dispersed nature + oxygen bearing quality of the alcohol will reduce the smokiness at higher power.

Actually quantifying in a measured fashion some of the disparities listed and currently being debated within that field:

Volumetric replacement gas - current experiments are with hydrogen and a "tipping point" of diesel as previously mentioned, although commercial ventures are not replacing more than about 25%, but all data is experimental. What is the ideal?

Hydrogen is being used because it is easily generated on board through electrolysis, but is hydrogen the ideal gas. Previously mentioned was I think acetylene.

One side of fuel efficiency argues for fuel heating for better atomization, the other argues for cooling for a denser charge. Someone is correct but a lab is a better place to find out.

Current technology runs a fast cycle diesel using compressed air and an aftercooler arrangement, but the history shows slower diesels running the "torque" side of the power curve. They were much less offensive, (deep, steady thumping vice screaming ) but is there other evidence of greater efficiency?

A lot to work on between these and the other mentions. Good luck choosing!

Emmett

Hello there,

Why don't you try enrichment of the fuel mixture with hydrogen?

You will find some info here : http://www.randolph-automotive.com/engine/hydrogen/

Then you can also try plasma ignition and plasma aftertreatment for NOx emission reduction.

Just a few ideas.

Randy,

Interesting reading there.

I've always been puzzled as to why it's always proposed to use an 'expensive' (such as hydrogen) fuel in such a wasteful energy conversion device as an internal combustion piston engine.

Your comments welcome.

Stu.

Thank you Randolph. I have been enriched in knowledge today and lost some of my irrational fears over handling Hydrogen.It was with a lot of trepidation in 1977 when I first tried C₂H_2.

However, in India of those days, there was no encouragement (financially) and I had to spend from my own savings, with the result that I am having to work hard even into old age and rely on meagre University R&D funding with attendant delays.

Your efforts as made visible are truly exemplary and I wish you all the best.

Regards

D.Ramakrishna Naidu

Thanks alote Randolph, you were so helpful.

AND A HUGE thanks to everyone who participated in that discussion.

Best Regards.

Dear Maverick2012,

what idea has hooked you, for taking up the project??

If it's not a secret, I'd be happy to know.

sincerely

D.Ramakrishna Naidu

Hi Randall:

I appreciate your link which includes a treasure trove of information!

Unfortunately, some efforts described are legitimate, and some are not. The CHEC system, for instance, would certainly appear to be fraudulent -- it's hard to imagine the physics coming remotely close to working, because one first needs to create an over-unity (perpetual motion) hydrogen generator to supply, to the engine, an amount of H2-energy-equivalent greater than the energy required to split the water.

In this system, they claim a current draw of 13 amps, which, at an assumed 24 volts, would be 312 watts. (They claim the system draws about as much as headlights. Headlights are typically 55 watts each, 110 watts total, so perhaps they were thinking of 12V trucks, for 156 watts... but the precise numbers are unimportant.) In any case, the energy content of of the hydrogen produced cannot exceed, giving them the benefit of the doubt, 312 watts. A realistic electrolyzer output (if theirs were very high quality) would be 75% of that, or about 234 watts worth of hydrogen. Given that truck engines are often operated at very high continuous outputs (100 kW average not being uncommon) it would seem that adding 234 watts worth of H2 to the intake air stream (.002 of the total fuel intake) would have little effect. There is no evidence that adding such tiny amounts of hydrogen to the intake air stream has any measurable effect. The only effect that could be reasonably expected is a slight shortening of the life of the alternator.

If one looks at the system efficiency of generating H2 on board via electrolysis, the prospects look even more dismal. If electrolysis is 75% efficient, and the engine is 30% efficient, and the alternator is 70% (a high estimate, vehicle alternators being remarkable inefficient vs other electric machines) then the process nets 15.8% of the energy needed to sustain itself -- let alone enough to produce an excess to serve as usable fuel for the engine. Just to produce enough H2 to have a net output available to fuel the engine (even to the tune of a couple percent of the total fuel input) would require that the electrolyzer be of several times higher than 100% efficient.

The CHEC system is much like the HAFC (which has shown up on CR4 many times). There is no credible evidence that either works, and the basic chemistry and physics involved suggests that neither could do anything but operate at a substantial net loss. For both, however, the amount of H2 generated is so tiny that the difference between some being generated (for the truck unit, let's say 230 watts worth) and absolutely none being generated would be impossible to detect even with a good dynamometer, let alone in over the road test.

The Arvin Meritor device, which was perhaps over hyped, suggest that 20% improvement in fuel efficiency could be possible -- possibly leading the unaware to think that getting such gains in efficiency is a simply matter of injecting some H2. On the contrary, that gain is based on first, throwing out the entire engine, and replacing with a smaller one, using not one but 2 precise injection systems, and turbocharging. The system was to be widely installed on 2004 model cars, per there earlier assertions. Clearly over hyped. Plausible? I think so, at least vaguely. Available tomorrow? Cost effective? Reliable? All open questions.

Sadly, some supporters of the obvious scams (just pop this HAFC on your car and get 50% better fuel efficiency) look at some of the Arvin Meritor hype for support: if this big company is involved in what seems like a similar idea (but is not) then there must be something to the idea of generating H2 onboard. (In another thread here we have a guy who claims the PICC "works" even though the PICC does not exist -- it appears to be merely a lure to sell the HAFC, which also does not work.)

But the basic fact remains that the articles for which you provided links are useful and helpful. Unfortunately, they will be misinterpreted by some, which is why I am posting these cautions.

In a thread elsewhere, I came across a post by someone who had tested one of the many H2 injection schemes. He said this:

I tested a 2.1 liter naturally aspirated DI industrial diesel on a precision eddy current dyno and used a Hy-drive hydrogen generation system. The engine tested is a much smaller engine than used in the trucking industry so the effect should have been noticible if there is any truth to the story.
There was no measurable effect on fuel consumption.
It is true that hydrogen can modify the combustion dynamics but simply adding a tiny amount of hydrogen into the induction system and expecting such great results is exceedingly optimistic.

"Exceedingly optimistic" seems like very kind words for fraud.

Dear all,

There is indeed a lot of information on the link I gave.

I think the most interesting documents are those by Radu Chiriac and Eran Sher. They show results of scientific and unbiased work. They mainly show some advantage at the low end of power/RPM in terms of emissions and consumption. The rest contains a lot of claims without having hard data. I decided to put it all there for giving you the possibility of better assessment. I am not forcing you to believe everything that is there. Basically I understand that hydrogen acts as a combustion enhancer but mainly in low power points. The high octane number of hydrogen of 130 can only be exploited if the engine is capable of higher compression ratios which in turn will improve thermal efficiency. Some work is still left. Up to you to do the remaining.

Best regards,

Randolph Toom