The future of the engine as we know it 1

[franzh]

I normally run like crazy when someone asks me questions about a "new" engine, but when one of my directors asks me to evaluate a "new design" design, my knees shake. That happened this morning.

We have seen free pistons, opposed oscillating pistons, scotch yoke pistons, toroidal blocks, ball valves, sliding sleeves, and tons of other combinations. Strangely, or not so strangely, none of these has ever reached any significant success. The old, inefficient Otto cycle engine still hangs around. With the exception of sealing refinements and air-fuel metering, almost nothing has changed in 100+ years, not including OHC engines which is a refinement, or phased cams, also a refinement, or exhaust aftertreatments, which is not a refinement, but an attempt at fixing an engine inefficiency.

I wonder how long it will take before something else pops up and takes a reasonably strong stand against the tried and true engine design?

Lets look at the true IC engine replacement, not hybrids (although I feel that is where we are heading for the next 25 years). Turbines are nice but not practical for a number of reasons.

When we look at H2 as a potential fuel, it still uses the Otto cycle engine as a base, only the fuel has changed. Are we really gaining anything on the engineering side? I recognize the significant advantage on emissions, but fuel transport, storage, and infrastructure have still to be perfected.

Any ideas, fellow engineers?
Franz


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[btrueblood]

Would you classify the Wankel rotary as a variant Otto cycle?

 

[franzh]

Since it operates on 4 cycles albiet in a different format, wouldnt it be considered an Otto cycle?
Suck, squeeze, bang, blow, along with a throttle, ignition, etc.
Works for me.
Franz

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[ewh]

Suck, squeeze, bang, blow also describes a jet turbine.

 

[franzh]

Thats a stretch, but I agree with your comment, but to classify the turbine as an Otto cycle? At least, that process is continual and not in significant sequences as the IC engine.
Franz

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[ivymike]

Gas turbine engines are still internal combustion (IC), right?

 

[tbuelna]

franzh,

The recip piston, Otto cycle, internal combustion engine is improving at a rate much faster than its proposed rival, the fuel cell. And there are still many significant improvements coming.

The main areas I see for future improvements in the Otto cycle piston engine are variable compression, variable displacement, various schemes for optimizing piston motion, and waste heat recovery through turbo-compounding (electric assist) or other techniques. There are also some improvements that can be had with real-time feedback provided by in-cylinder combustion sensors.

I used to work with this old German engineer, who would respond to predictions of the demise of the internal combustion engine with the following:

"The hearse that drives you to the graveyard will have an internal combustion engine".

 

[franzh]

We are pulling at semantics classifying a turbine engine in the same category as the Otto cycle piston and valve engine. As good as the turbine engine is, it really shines in constant load applications, far superior to the piston engine, but it cannot compare to the piston engine for throttle response and manufacturing costs, necessary for daily driving and private operation. Toss in the efficiency of the turbine compared to the versatility of the piston engine and we have a real discussion.

The conventional piston and valve engine has made significant advancements over its century plus life, certainly nothing to sneeze at, but most of the major advancements have been made in the last 20 years when electronics took a major role in design and controls. Recognizing the items "tbuelna" lists, these are still refinements of the original design, basically correcting and improving on a design that originates almost 150 years ago.

Where do we go from here? In my lifetime, or at the end of it, I too will be taken to my grave in a hearse powered by an Otto cycle engine, most likely.

The fuel cell will increase in popularity, but there is going to be a point where increased production will not significantly lower the cost per kilowatt, and we will need more power to make a transference of dominance between the piston and fuel cell powerplant.

Surely there must be something in the interim.

Franz

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[MGaberik]

Diesel Cycle engines are becoming increasingly popular in personal transportation due to the increased efficiency compared with Spark Ignited (~Otto Cycle) engines.
Gas turbines approximate the Rankine cycle, I believe.
All have there advantages and disadvantages.
The basic mechanical engineering was fairly well thought out 100 years ago. The big advances have been materials and electronics (thank you DOD and NASA). The advances are helping the engine types compete where they traditionaly did not have an application.

 

[Warpspeed]

Fascinating stuff.

A hundred years ago we had DOHC four valve per cylinder engines, and even turbocharging. In some ways not much has changed, but in other ways the perfection and understanding of the basic process has evolved vastly.

I see future improvement in fuels and lubricants, engine management, materials technology, computer simulation, and a whole host of other things.

Evolution not revolution.

 

[franzh]

Warpspeed: Evolution is correct, as everything has up to date, but at some point, we have created what may be the most efficient piston and valve IC engine, where even better development is far more difficult and expensive than the gains. We have seen the gamut in technology with the resurfacing of turbocharging and supercharging, variable cam timing, SAAB's variable compression engine, and so on. What we are doing is evolving the engine. True, we had DOHC 4 valve engines a century ago, but were they 2 litre 8000 rpm 600 bhp? That is the true note of evolution, thanks to electronics, lubrication, material selections.

With computers, we have the theory that the speed of the processor shall double every 18 months, and it has done so, but they have hit a stumbling block with the capacity of the pathways hitting the width of the laser in NM.

Wonder when we will hit that same point with the IC engine, where there just may be no further development possible? I consider the newest generation of engines the epitomy of engine technology, truly the best of the best, but then someone squeezes a little more, makes one a little cleaner.
Franz

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[GregLocock]

I'll just jump on my usual bandwagon and say that the Prius, in particular, has the potential to remove most of the problems associated with running less flexible, but more efficient, engines as the primary energy source. Admittedly, this comes at a huge weight penalty.

I'll jump back off the bandwagon, and ask, is the current choice of materials the limit on SI engine efficiency? How about CI?

Certainly for production SI engines we do some very stupid things, efficiency wise, to keep the exhaust valve and cat cool.

Oh, and perhaps I am still focussing too much on thermodynamic efficiency. I see no real sign that the consumer marketplace is much concerned with efficiency in any real sense.



Cheers

Greg Locock

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[franzh]

This group has had this discussion before. Are the Prius and other new generation hybrid vehicles engines actually the source of efficiency, or is it the total package? The cost of fuel going in, versus the energy derived and applied to the ground. I like the hybrids for the gee-whiz factor, but for pure engine efficiency, are these engines that efficient?

The Prius, Honda Civic, and other semi-related hybrid projects are currently cutting edge, but the Honda Civic has their high fuel efficiency engine that approaches the economy of the Hybrid, as does Toyota (American market) and others. Not having access to the much of the worlds offerings limits my exposure, but I am certain that there are other options.

Down to basics:
With the exception of some materials selections and minor engine developments, the engine has remained unchanged from the turn of the century (the last one) up until post war, around 1950. Lets see if this is an accurate recollection:

Overhead valve engines were common place, improving air and fuel management, late 1940’s, and I know there were some pre-WWII, but widely accepted OHV engines were not generally available until after the war.
European manufacturers used the OHC engine, leaping over the US manufacturers.
Thin wall castings reduced engine weight;
Staged venturi carburetors improved on air and fuel mixing, improved power at low speeds and helped with emissions, something of little concern in the 50’s and early 60’s.
Early emission controls like the EGR valve and Air injection system. Are these developments or patches to cover up an engine design deficiency?
Electronic ignition;
Early electronic fuel injection;
Electronically controlled carburetion disasters of the US 80’s.
Central single point fuel injection;
Bank fire fuel injection;
Sequential fuel injection;
Tuned intake manifolds help with power;

But, almost all of these systems use engines designed in the 1950’s and 60’s. The 1990’s introduced the computer designed clean sheet engines which are further refinements of the earlier designs. In the US, the Chevrolet small block was the engine used from 1955 until 2002 with almost no significant design changes, Ford used the small block from 1962 until 1998, and Chrysler is still using their small block, first introduced in 1965, still in production. Air management and electronics are major developments, but the basic engine is unchanged. Was that because the engine was that good, or “why reinvent the wheel”? Ford now uses the modular engine, which is quite good, and GM is using the LS engine, which is quite good too, and they are clean sheet engines, designed for emissions but serve double duty as good powerplants.

The consumer has no real care about thermodynamics, only that the automobile starts with the first twist of the key, has reasonable performance, costs as little as possible to operate, has no unexpected breakdowns, and frankly, emissions are far down the list. US manufacturers have found that advertising a car has having low emissions has little or no impact on sales, but change the interior color or add a nice sound system, and now we increase sales. See the phenomenal sales of the grossly overweight SUV market proves that the consumer has little concern for emissions or economy, only status and usability. Also, I own one too, but was lucky in my selection as it performs well with economy and emissions.

Early in my career, I read that we will see ceramic engines and engine components that will last forever, ultrasonic fuel atomizers to insure proper fuel distribution, plasma ignition for total combustion, cylinder head inserts for heat reflection, and so on. Ultra capacitors will be used for starting and electrical load, no starters and no alternators.

What next?
Franz

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[rmw]

I am on record in this forum as having predicted the advent of diesel as the worlds primary automotive fuel. I base this on recent activity in the arena of the Fisher Tropsch process of converting (stranded) Natural Gas (and/or coal or other suitable hydro-carbon) to light distillate.

The fuel that this process produces has already found favor in some USA markets like California because of it's ability to A) blend with petroleum diesel to reduce sulfur emissions, and B) eventually replace sulfur bearing petroleum diesel as an "acceptable" fuel.

Europeans, whose governments tax the fuel quite heavily already care about the Otto cycle efficiencly of the diesel engine over gasoline, and seem to be leading the charge.

There is a lot of NG around the world that not much else can be done with it other than convert it to a marketable product (ammonia, chemicals, F-T diesel, etc.) Some of the owners of this gas seem quite serious about going down this path.

Just my $0.02.

rmw

 

[franzh]

The diesel cycle circumvents many inherent deficiencies present in the Otto cycle/4 cycle throttled engine. There is a lot to say for the diesel engine efficiency, those that I praise. The FT process, and other related GTL projects are gaining in popularity, and when enough of the product becomes in demand to drive the prices down where they are directly competitive, we will see more of a concerted effort towards CI engines.
Also, look for more Ethanol-Diesel blends, just 10% Ethanol has shown positive benefits over standard #2 diesel.
If I had my choice? I would buy a diesel, but my missus would refuse to fill it when she drives, says its “stinky”.
Franz

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[GregLocock]

Sorry Franz, I wasn't clear. The Prius transmission is effectively a full authority CVT, AND has energy storage. Therefore you can afford to run an inflexible engine, at its optimum operating point for the required power demand, and rely on stored energy the rest of the time. In my opinion none of the other hybrids come close. A Prius transmission with an efficient diesel/turbine cogenerator setup would be my choice for a near term solution if the current fuel economy fad persists.

Incidentally, the total energy stored in the battery is about the same as a pint of fuel!



Cheers

Greg Locock

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[SMOKEY44211]

Here's my take on this thought provoking question. Unless battery technology makes a major break through in the next 10 yrs. I'm going to my grave in an IC powered hearse. Given the average life expectancy and the lord willing I've got about 20 yrs to go. I think further improvements in the IC engine that will occur in that time will come from efforts to cut down thermodynamic losses on the exhaust and cooling system. I think a homogenous charge 2 stroke turbo-compounded diesel with ceramic coated piston head and combustion chamber, seems like the next logical progression in IC engine development. Given current technology in materials and manufacturing this should address fuel ecomomy and emission issues. Politics and economics will be the determining factor as to how quickly this will occur.----------Phil

 

[evelrod]

I guess it's time for me to add my two cents...

I have stated before that H[sub]2[/sub] will never be widely used as a motor fuel, period.

I drive a diesel truck but I see no future in diesel power in general transportation unless the automakers undertake a massive advertising blitz to convince the average driver that diesel is not, as Franz put it, "stinky".

The current fad/trend in SoCal is the "hybrid". Anecdote: My tax accountant has two Prius approaching five years old...so far, so good---one approaching 150,000 miles with no maintenance. My question is...What happens when all these batteries must be replaced after the warranty period?
At this time you cannot find a Prius in my area to buy unless it's used and only then at a price that generally exceeds the MSRP of a NEW car!

Franz, I agree with most of what you post. However, Buick never produced anything but OHV engines (The Marquet used a side valve Olds engine). Chevy used OHV fours and sixes (Chevy had an OHV V8 pre 1920 but did not procuce it). The "flathead" was popularized by Ford, of course, but in the pre WW II era, flathead and OHV engines were of similar HP output and reliability...cost being a big factor for continuing the flathead into the 1950's (along with Henry Ford's single minded approach to auto production). Cost of production change was most likely a factor with Chrysler and others (even Packard had pre war OHV engines).
Of course...the exotics...DOHC, SOHC,etc. widely available at premium prices. Early aircraft engines (WW I) were OHV, e.g., Liberty, Hispano-Suiza, etc.
My point with all this is to point our that, IMO, 1950 was NOT the departure line from 'old tech' to 'new tech'.
If I were forced to pick ONE day where the transition began...December 7, 1941.

Rod

 

[patdaly]

Rod, one thing you may be overlooking in regards to diesels would be the biodiesel revolution. For the diesel to take over in the US, the majority of fuel sold would be required to be something other than petroleum based, and by all accounts I have read, even Bio. produced from Algae has none of the stink associated with dino. diesel.

When I finally do get to converting the wifes car to diesel, she will have exactly 2 choices, fill it or.............

 

[JayMaechtlen]

... ceramic engines and engine components that will last forever

It's "cost of ownership".
Most cars start to look pretty beat up with 200,000+ miles on them... How much value do you add to make the engine run 300k? 400k?

" ultrasonic fuel atomizers to insure proper fuel distribution"
why would you bother when the efi multipoint handles that very well?

"plasma ignition for total combustion"
huh? who cares? 100k miles on a set of plugs, they run plenty clean enough for the cat to clean up (think you can make the plasma ignition good enough to eliminate the cat converter?)
"cylinder head inserts for heat reflection"
? the name's Rogers... Buck Rogers.
(or is it Tom Swift?)
Yes, definately if you could reflect/stop heat transfer into the head & valves you could improve efficiency and reduce heat load on the cooling system.
(what was that about cost of ownership?)

" Ultra capacitors will be used for starting and electrical load, no starters and no alternators."

huh? An Ultra Cap is just a means of storage. How ya gonna make those electrons spin the crankshaft?
How ya gonna recharge the Ultra Cap after using it to start the motor and run the lights and accessories?

Jay





Jay Maechtlen

http://home.covad.net/~jmaechtlen/