PDA

View Full Version : To build a better hybrid... Maybe?



A.K. Boomer
05-18-2012, 07:20 AM
My mind was working overtime the other day and once again it started chewing on what's on allot of peoples minds nowadays - efficiency of vehicles,

I normally always get fixated on either the exhaust waste heat or the exhaust combustion, (they are not "one and the same")
the waste heat could be used to run some kind of sterling type apparatus - or maybe some kind of steam powered deal, but either adds a plethora of complexities in then having to either carry water (that will freeze in the winter) and or another type of engine and all it's complexities...

Just not practical,

So I end up back at the exhaust combustion --- This is what drives your typical turbo-charger - it's gasses still expanding, it's gasses still being burnt, therefore -
In order to properly understand the turbo charger one has to look at the exhaust between the cylinder head (backside of the exhaust valve) and the turbine for what it is - a secondary combustion cycle. Turbo's do not operate on heat - they operate on pressure, therefore expansion is needed between this space - therefore fuel needs to be burnt in this area and is, Like iv stated before - it's part of doing business with the IC piston engine and having to crack the exhaust valve open even though the combustion stroke is still going on - keep in mind this stuff is happening real fast and we have to get the chamber cleaned out in order to properly introduce the next charge...

The reason why im so adamant about getting this point across is to spare myself all the "over unity" BS that most kneejerk hillbillies are going to be salivating to write... so please spare yourself the embarrassment, there is no "over unity" here, there is real work being done with fuel that would otherwise be used to just heat up a cat...

Typically in a turbo charged engine we use this energy to spin another turbine to compress air and pack in another half a atmosphere into an engine for better performance --- this is no small task, and it's testimony to just how powerful turbo chargers really are,
in many ways it's a great design --- turbines are actually a very small package - are now very trouble free and can easily outlast the engine itself, and using one turbine to drive another allows for great tractability...

So what if we were to just use this wasted energy direct and instead of using it to compress the intake charge we used it to put power back into the system in the name of efficiency - we could leave the engine's stock compression ratio alone, and just route the power back to the crankshaft, of course it's not going to be any "huge gain" like what typical turbochargers do by effecting the intake charge - and in fact its going to be just a teeny fraction, but remember - this is not about power - it's about efficiency, and extra work is being done with otherwise wasted fuel.

Im convinced that the reason we have not seen any attempts at this is due to it being impractical mechanically - there's no real way to harness those kind of RPM's and reduce them and have them be load sensitive and be able to spool up and on and on, It would take a small CVT transmission in itself - crazy,,, this is beyond just waste gate control, this is complicated...

But it's not complicated if you enter the hybrid, the turbine could be linked to a computer controlled gen/alt --- this in turn (no pun intended) could be utilized to put power back into the system AS the car is being driven in both city and highway conditions...
A little high rpm generator - a long shaft that keeps it away from the heat - a computer controlling the perfect ratio's of gen/alt drag and waste gate control...

here's what you most likely end up with, an engine that's just as powerful (a price has to be paid in exhaust restriction) yet it's overall CFM is reduced - this equates directly to increased efficiency...

So imagine not just synergy drive rewarding you when your stopping for that stop sign, imagine your batteries being charged slightly when your taking off from it too,
I know - I know, one more piece of crap to go wrong, but it's a hybrid - why stop now...:p
Talk amongst yourselves --- I have to work today so spankings will be given out sometime later... ;)

The Artful Bodger
05-18-2012, 07:38 AM
Not over unity and quite well tested and understood, most notable example was the Wright turbo compound aero engines where, if I recall correctly, the power output of the exhaust turbines was coupled to the crankshaft by some hydraulic system.

For use in a car, and I suggest this might even be practical for a home shop project, the output of a turbo alternator could be used to electrically drive ancilliary loads that would otherwise be driven by the crankshaft, for example air conditioner compressor, coolant pump, oil pump and all vehicle electrical loads leaving crankshaft power available to actually propel the vehicle.

The challenge is an alternator that could be spun at turbine RPM, maybe some variation of a Faraday Disk?

willmac
05-18-2012, 07:57 AM
The Napier Nomad (two stroke diesel) was an extreme example of this type of engine. Running more than 60 years ago and producing in excess of 3000 hp. The engine had great promise, but by that time the turbo prop had developed so rapidly that the complexity of the approach did not make commercial sense.

J Tiers
05-18-2012, 09:30 AM
Any extraction of energy from the exhaust has to be considered carefully.....

In the first place, exhaust "friction" lessens the amount of air that can be inducted into the cylinder...because the exhaust hasn't exited yet...... that primarily affects ultimate power capability, but since the piston etc friction is reasonably constant, less power per cylinder would mean that much less efficiency.

if "X" amount of energy is released by fuel, and you remove energy in one place, there is less that can be removed elsewhere, it is a balance. A turbocharger packs more air in, (or fuel mix) and offsets its added exhaust friction by increasing engine power. Power, again, which isn't the main issue, but power per cylinder might be.

The energy in the exhaust is in several forms.

First, of course, it is hot. That is hard to extract effectively, but a stirling engine could indeed run a generator, for instance, as you note. With suitable electronics, the generator voltage would be relatively unimportant, the output could be anything.

Then also it is pressurized, and that can be used in a turbine running a generator, or other utilization equipment.

Thirdly, it has mass and is flowing, which again can be used in a turbine.

The CVT approach is probably a complete non-starter due to complexity and friction resulting.

Electricity is a sort of universal conversion, which can be used as-is to take a load off the alternator, or can run a motor to do anything required, from aiding propulsion to whatever. Efficiency can be quite high, so extra conversions need not be a barrier.

But, the exhaust energy extraction has to be a net gain...... it is easy to get energy from it, but harder to prevent that from subtracting from the other useful power.

Thing of it is, the turbine/turbocharger is about the simplest possible way to utilize the energy. And it directly offers a substantial power gain. One way that can be a benefit for efficiency is to allow use of a smaller engine for equal performance.

Bearing in mind your total and unconditional condemnation of all hybrids, the ability to use a smaller engine with lower losses (because it is utilized at a higher percent loading most of the time) and still get higher demand power due to supercharging should be attractive in comparison to any sort of electric assist hybrid, etc.

However, one big efficiency gain is to turn off the engine.... when it isn't required. That probably will be far more effective in increasing "global" efficiency for most cars driven in traffic than any amount of pure engine efficiency gains.

Nobody really CARES about the energy efficiency of the engine directly. What people care about is how much fuel they have to put in to accomplish the task they want to do.

That task is generally to get from "A" to "B"..... with some side points of doing so "in a stylish car that says I am rich and important" that are an issue for to some of the "self-appointed nobility" who insist on driving "statement cars" such as BMW, Lexus, Daimler, or perhaps Audi.

So, the important thing is not isolated efficiency, but overall efficiency, usually measured as distance vs fuel (MPG, LPM, etc). That is not 100% an engine efficiency issue, although that is a component of it.

vpt
05-18-2012, 09:44 AM
What about using the exhaust to make steam to power a steam engine?

Weston Bye
05-18-2012, 10:01 AM
I work in automotive electrical devices, so I get to see some of the attempts and theories that automotive engineers discuss and investigate. JTiers touched upon conversion of exhaust to electrical energy. The simple method is a multitude of thermocouples wired in series exposed to the hot exhaust gases. Each thermocouple contributes its current at millivolt levels to lighten the electrical load on the alternator, or at least power some of the "conveniences" in the vehicle. Efficient? Cost effective?

I remember the Corvair (bad idea) and VW (not as bad, but...) waste heat cabin heaters...

A comment about the carping I hear about the low efficiency of the internal combustion engine: What out there is better? What better fits our infastructure? What other technology can perform better in all climates and driving conditions. The IC engine, (and petroleum fuel) for all its shortcomings, has proven to be the most versatile power source we have.

If we had it to do over, what historically would have been better?

wierdscience
05-18-2012, 10:30 AM
A comment about the carping I hear about the low efficiency of the internal combustion engine: What out there is better? What better fits our infastructure? What other technology can perform better in all climates and driving conditions. The IC engine, (and petroleum fuel) for all its shortcomings, has proven to be the most versatile power source we have.

If we had it to do over, what historically would have been better?

Nothing,it was all sorted out in the marketplace a hundred years ago.People fail to remember we had attempts at steam and electric autos back then and probably a few others as well,I seem to remember one attempt at a Horse on a treadmill,but gasoline won out simply because it was the best choice.

Our politicians should remember we can't just legislate new technology,if they did remember that it would save us a lot of money.

Any new technology intended to replace an existing one has to deliver the same or better performance and at the same or reduced cost for it to be accepted by the marketplace.

When was the last time any of us purchased by choice a product that delivered less and cost us more?

justanengineer
05-18-2012, 11:52 AM
The reason that doing as you describe (mechanically operating other components off a turbo) is done in very RARE cases and not in automotive applications is bc doing so in such an application would lead to an efficiency loss. Basically, you lose more power doing so than if you simply mechanically drive it, unless the engine and turbo are operating in such a narrow operating envelope (think stationary engine) as to make it feasible.

dlsinak
05-18-2012, 12:39 PM
Just for giggles look here............ 100mpg

http://afstrinity.com/

GadgetBuilder
05-18-2012, 01:30 PM
Not to hijack the thread but improvements in vehicle efficiency needn't be to the engine. Back in the 1960's I drove a Saab which had free wheeling - when the accelerator was released, sprag clutches on each axle released and the car coasted with the engine idling. It took practice to get used to it, one needed to plan ahead farther for stops (something that still affects my driving). And when picking up RPMs after coasting down a hill one had to do so gently to avoid a thump. One could lock free wheeling out but doing so cut gas mileage by about 20%. Engaging reverse automatically locked it out, else you wouldn't be able to back up ;)

It seems like if the computer controls on today's cars could be tweaked to minimize emissions at idle then this would be a simple way to get more efficiency. Of course, cruise control was uncommon in that era so that could be an issue now.

John

T.Hoffman
05-18-2012, 02:10 PM
I know electric cars have been tried in various ways for over 100yrs.
Here's a 1909 Baker electric car that still operates:

http://www.youtube.com/watch?v=O9vC3S8MJPY

philbur
05-18-2012, 02:20 PM
I haven't read it all but I didn't think that a turbo uses what would otherwise be wasted energy. I thought the engine/turbo system was designed to ensure some enegy is left over in order to drive the turbo.

I think your first thought of finding a way to effectively use the waste heat would be more productive.

Just a passing thought
Phil:)

RWO
05-18-2012, 02:30 PM
Today's fuel-injected cars cut off the injectors when coasting with no throttle input. The transistion back to fuel input is so smooth the the driver never feels it.

Most of the hybrids utilize Atkinson cycle valve timing which makes the engine more efficient as well as reducing the cylinder pressure when the exhaust valve opens to near atmospheric. This doesn't leave any energy to operate a turbo-charger or any other exhaust energy recovery device worth it's cost and weight.

RWO

danlb
05-18-2012, 03:35 PM
Just for giggles look here............ 100mpg

http://afstrinity.com/

That is some of the most inventive math I've seen in a while.

from that web site:
"150 Miles Per Gallon. Mileage is based on a typical week of driving: 40 miles, 6 days per week and 100 miles on one day each week. The first 40 of every day are electric and gasoline is used for longer distances."

So it actually gets about 44 MPG after the first 40 miles.

Personally, that is not a really bad result, but no better than other plug in hybrids. Of course, they make a lot of assumptions, such as $7 a week for electricity at $0.06 per kWh. I pay $.33 for mine. :) And that 40 miles on battery is at city speeds ( under 25 MPH) , not freeway where it will (according to their charts) be closer to 20 miles.

When the batteries are proven to be as good as in my current hybrid ( 10 years of use as of next month) I'll probably switch to a plug in hybrid if my commute remains as wild as it is now.

Back on topic:

I like the idea of a turbo driven generator. The question in my mind is...

It will decrease engine efficiency a little to run a turbine. How much power does it take to spin the turbine unloaded in a conventional engine? I know a supercharger will suck many HP to run the blowers. How many HP does a gas engine lose due to the increased back- pressure of a turbo?

Logically, if there is no increased back pressure there is no energy available to do work. My car, at freeway speeds is pumping 30 Cuft per minute at a fairly low pressure. ( 1.7 liter 4 cyl at 2k rpm)

I've heard that if you clog up the muffler (remember 'GlasPac' mufflers?) your engine performance went down the drain. Adding enough back pressure to extract 20 HP to turn a generator seems like it would be a similar situation.

Dan

becksmachine
05-18-2012, 04:12 PM
So I end up back at the exhaust combustion --- This is what drives your typical turbo-charger - it's gasses still expanding, it's gasses still being burnt, therefore -
In order to properly understand the turbo charger one has to look at the exhaust between the cylinder head (backside of the exhaust valve) and the turbine for what it is - a secondary combustion cycle. Turbo's do not operate on heat - they operate on pressure, therefore expansion is needed between this space - therefore fuel needs to be burnt in this area and is, Like iv stated before - it's part of doing business with the IC piston engine and having to crack the exhaust valve open even though the combustion stroke is still going on - keep in mind this stuff is happening real fast and we have to get the chamber cleaned out in order to properly introduce the next charge...



Did we all miss this part?

Or do we all just disagree with it??

Dave

Forestgnome
05-18-2012, 04:31 PM
Did we all miss this part?

Or do we all just disagree with it??

Dave
He said he was trying to head off a discussion on this. I was trying to stay quiet, but since you mentioned it, I don't agree with the statement.

The Artful Bodger
05-18-2012, 04:56 PM
Did we all miss this part?

Or do we all just disagree with it??

Dave


I agree with this, furthermore it is old proven technology to recover waste energy from the exhaust system to increase total engine output while not increasing fuel consumption.

The challenge is to do this in a practical way in a road vehicle. My suggestion is use it to drive power-sapping engine and vehicle ancillaries, fans, pumps, compressors, battery charging et al.

Thruthefence
05-18-2012, 06:25 PM
Wright R-3350 Turbocompound radial engine

http://dc250.4shared.com/doc/O9NN9LJz/preview009.png

philbur
05-18-2012, 06:43 PM
Here's the text that goes with it.

Near the end of World War II, someone got the idea to
harness the wasted energy in engine exhaust by using
the exhaust to drive a turbine that was coupled to the
engine crankshaft. This process is called turbo-
compounding. Although numerous engines had
experimental test programs with turbo-compounding,
only the Wright R-3350 Turbo Cyclone ever saw wide
service. Referring to Figure 18, notice the three large
pressure recovery turbines spaced equally around the
aft side of the engine. Each of these was fed by the
exhaust from six cylinders and contributed nearly 200
additional horsepower (600 total) to the engine output.
Another advantage of turbo-compounding is the
exceptionally good fuel consumption.

A better picture and the text is on page 9 of this link:

http://dc250.4shared.com/doc/O9NN9LJz/preview.html

Phil:)


Wright R-3350 Turbocompound radial engine

http://dc250.4shared.com/doc/O9NN9LJz/preview009.png

Yow Ling
05-18-2012, 06:46 PM
A couple of questions, given the 30/30/30 splitof usefull work, heat to cooling and heat to exhaust. How much energy does a traditional turbo recover? how much does it affect the split?
Using a turbine to extract the free power in the exhaust is not new, most helicopters and turboshaft aircraft engines get all their power from the exhaust gas using a free turbine, the only real difference is the gas generator, IC engine in your case, combustors in the aircraft version.
Turbochargers recover alot of energy, how big would an electric powered compressor be that can deliver 200cfm at 10-15 lbs, but then in the economy stakes you are looking at how much energy is left to recover, not many if any.

becksmachine
05-18-2012, 08:00 PM
I agree with this, furthermore it is old proven technology to recover waste energy from the exhaust system to increase total engine output while not increasing fuel consumption.


I wasn't very clear, I am agreeing with it also.

Judging by the number of responses that mentioned losing power due to increased back pressure, it seemed that not everyone does believe. ;)

Dave

A.K. Boomer
05-18-2012, 11:07 PM
For lots of people "power" is where their mind goes, but remember this is not just about power, it's about efficiency - as I stated in my first post one of the best examples to use to keep things simple is even if it just broke even but utilized less CFM in the process to do it;

"an engine that's just as powerful (a price has to be paid in exhaust restriction) yet it's overall CFM is reduced - this equates directly to increased efficiency..."

If the engine is producing the same amount of power yet is using less fuel and air to do it then this equates directly to efficiency...


I am amazed that each time I think im thinking of something new the Artful Bodger has a likely example that's been done in the past in one way or another,:p

but - this system would be totally new in some ways (I think?)

and the hybrid is the perfect vehicle to take advantage due to not having to go the mechanical route,
think of the control you would have over the turbine, computer controlled drag at any given RPM with the gen, and computer controlled waste gate both working in perfect harmony using most of the already in place engine sensors (throttle position/air flow meter/map/ect./ect.)

And what would you have to add on? about a half a turbo system eliminating most all of it's plumbing and intercooler - a really high tech little generator with maybe a high quality planetary reduction gearbox, all this coupled to a brain box and you would be able to harness gains never before achieved --- but would it still be worth it after all the conversions? the gen to batterys and then back to main motor?
Or should you go even more direct - skip the batterys and just use it to add more umph,,, so whenever the turbine is called upon you use the small gen to throw that energy directly at the electric motor and use it up on the spot... less throttle same speed.

RWO brings up a very good point about some hybrids and the atkinson cycle - but could it be enough of incentive to abandon that if we are actually getting work done with the wasted gasses?

I don't know - just throwing it out there for you guys to crunch - helps me from going insane, or maybe pushes me closer to it...

A.K. Boomer
05-18-2012, 11:20 PM
Not to hijack the thread but improvements in vehicle efficiency needn't be to the engine. Back in the 1960's I drove a Saab which had free wheeling - when the accelerator was released, sprag clutches on each axle released and the car coasted with the engine idling. It took practice to get used to it, one needed to plan ahead farther for stops (something that still affects my driving). And when picking up RPMs after coasting down a hill one had to do so gently to avoid a thump. One could lock free wheeling out but doing so cut gas mileage by about 20%. Engaging reverse automatically locked it out, else you wouldn't be able to back up ;)

It seems like if the computer controls on today's cars could be tweaked to minimize emissions at idle then this would be a simple way to get more efficiency. Of course, cruise control was uncommon in that era so that could be an issue now.

John

Yes I too had one of those - and worked on them also -- they were not sprags though - it was a single roller clutch and it was inside the transmission and boy what a PITA to put back together if they came apart on you --- I did it with feeler gauge material.

Like RWO mentioned - todays fuel injected vehicles totally cut the fuel off during coast mode --- you won't coast as long as the Saab but you will burn zero fuel whilst doing it,
In the city and mild hills the old Saabs would still come out ahead --- down steep grades like where I live and the newer fuel injected vehicles win because they don't burn one drop,
This is really evident coming down from my bro's house in the winter --- the heater does not kick in till about 10 miles later when you hit the flats...

The old Saabs really came out on top "back in the day" - even though the engine was still allowed to Idle it was far better than what everyone else was doing which was creating extreme intake vacuum and pulling extra hard on their Idle circuit all while creating vehicle drag...

wierdscience
05-19-2012, 12:46 AM
Here's the text that goes with it.

Near the end of World War II, someone got the idea to
harness the wasted energy in engine exhaust by using
the exhaust to drive a turbine that was coupled to the
engine crankshaft. This process is called turbo-
compounding. Although numerous engines had
experimental test programs with turbo-compounding,
only the Wright R-3350 Turbo Cyclone ever saw wide
service. Referring to Figure 18, notice the three large
pressure recovery turbines spaced equally around the
aft side of the engine. Each of these was fed by the
exhaust from six cylinders and contributed nearly 200
additional horsepower (600 total) to the engine output.
Another advantage of turbo-compounding is the
exceptionally good fuel consumption.

A better picture and the text is on page 9 of this link:

http://dc250.4shared.com/doc/O9NN9LJz/preview.html

Phil:)

Thanks for posting that,fascinating reading.

J Tiers
05-19-2012, 01:32 AM
WEll, I DO NOT agree with the premise of extra burning etc....... but the idea of extracting energy is certainly possible.

You have pressure, because the cylinder exhaust is not expanded to atmospheric, it has considerable pressure available. You can use that in a way that loses more than it contributes, or you can use it as a net gain.

IF you can get more power (and YES I do mean POWER) from the exhaust, you increase efficiency because you have not burned any more fuel to get that added power. It must be done carefully, but if you come out with more power in the shaft without burning more fuel, all is well according to AKB's "line in the sand", and that clearly can be done.

The system is very well known, it was done way back when by putting a 'topping" turbine on the exhaust of a reciprocating steam engine. The output in those cases could (I believe the Titanic's center shaft turbine did 100 years ago) rival the reciprocating engine power, and of course was an efficiency as well as power gain. They had the advantage of 12 or so more lb pressure, due to condensing, of course.

The issue is that you get the power in a form that may not be the most convenient.... a variable mass flow, which probably will require a complicated system to connect to the driveshaft mechanically. AKB alluded to this.

An obvious answer is electric transmission, which can convert almost any voltage and current to match a shaft speed and input torque to it. A turbine driving an alternator is capable of a wide range of output, and that output is convertible at high efficiency to other speeds.

Complaints will no doubt be made about losses and complication, but to those people I offer the very wide world of mechanical contrivances to attempt to do the same thing. Most will offer much more complication, at least the same losses, and a substantial cost penalty.

Gear drives, hydraulic coupling (generally in the form of a torque converter), electric coupling of various sorts, ALL have been used on ships before. The CVT I don't think has been on ships, but I can't prove it. Ditto for belt drives.

Electric will come out looking pretty good in almost any comparison.... which is one reason why the VFD in various forms is now in your washing machine, in electric cars, in every machine tool, diesel locomotives, whatever..... even in the tiny fan that cools your computer CPU.

Willy
05-19-2012, 02:13 AM
Detroit Diesel's 15 and 16 liter engines are also using compound turbos to directly link to the engines. The second power recovery turbine is mechanically geared to the engines flywheel. On the 15 liter engine Detroit claims a gain of 50 HP. A very significant gain from a 500 HP engine.

Cummins is due to bring out several engines in the near future using a Rankine cycle heat recovery system that is hoped to bring a 10% improvement in efficiency by utilizing the recovered waste heat to spin a turbine/generator.The electricity from this will be used to power a flywheel motor-generator.
The Rankine cycle heat recovery system is already a very well proven concept in power generation systems and large marine diesels.

Although turbochargers are often unjustly criticized for being a cork in an engines exhaust, one has to keep it's role in power enhancement in perspective. They serve a very effective role in permitting engines to perform up to their true potential.
The fact that it may impede exhaust gas flow to some extent should not detract from it's ability to produce power.
Basically it's the price of doing business. Much as it takes a substantial amount of energy to pump air through a naturally aspirated engine. How about the energy required to compress the charge in the combustion chamber, pump lube and coolant?
There's still a lot of room for improvement in all of these areas.
I have witnessed over at least 30 years many commercial engine manufactures use of some very unique strategies in order to lessen the parasitic drag that all of these systems place on efficiency.

Good topic. The boat always seems to move much too slowly though.
But this is an intrinsic human trait. We always want what we don't have.
This keeps us striving to achieve goals that always seem slightly out of reach. End result is technological progress. We've come a long way but there's still no end in sight to were we want to be.

elf
05-19-2012, 03:03 AM
Any new technology intended to replace an existing one has to deliver the same or better performance and at the same or reduced cost for it to be accepted by the marketplace.



or just raise the price of the existing technology :mad:

darryl
05-19-2012, 03:55 AM
The electric drive train is sufficiently evolved- it's the carrying of the 'fuel' that is problematic. When you have the latest and greatest in batteries, you also have the 'bomb' problem- too much energy stored in a small space. Even if you could recharge this 'tank' reliably and cost-effectively with existing technology, this barrier will always exist. In my opinion, it's doubtful that we'll ever be allowed to use an 'electric storage tank' that is evolved as well as the drive trains have become.

This seems to be one of the basic barriers to electric vehicles becoming truly practical. For some reason, a tankful of highly flammable liquid fuel isn't being placed into the same category- could it be that the evolved electric vehicle system is just too much of a threat to the existing business of selling liquid fuels- hmm. Why would big auto and big petroleum support a change over to practical electric transportation- unless of course they could make big money at it-

Which brings me to one of the points I'm trying to make- even though electric drive is basically quite simple, it will never be offered to the public except at a premium. We've been hearing all these years how it's going to be cheaper, etc, but the business of putting transportation into the publics hands is never going to allow that.

Not the least of the concerns is how to charge all these batteries- as has already been stated, the existing and forseeable power generation and distribution systems are not going to be up to the task. And if we take a look at our 'need' to have 2000 lbs of machinery to transport 200 lbs of body around- well, the picture certainly doesn't look good for wide-spread electric vehicle usage.

Yow Ling
05-19-2012, 05:13 AM
The electric drive train is sufficiently evolved- it's the carrying of the 'fuel' that is problematic. When you have the latest and greatest in batteries, you also have the 'bomb' problem- too much energy stored in a small space. Even if you could recharge this 'tank' reliably and cost-effectively with existing technology, this barrier will always exist. In my opinion, it's doubtful that we'll ever be allowed to use an 'electric storage tank' that is evolved as well as the drive trains have become.

This seems to be one of the basic barriers to electric vehicles becoming truly practical. For some reason, a tankful of highly flammable liquid fuel isn't being placed into the same category- could it be that the evolved electric vehicle system is just too much of a threat to the existing business of selling liquid fuels- hmm. Why would big auto and big petroleum support a change over to practical electric transportation- unless of course they could make big money at it-

Which brings me to one of the points I'm trying to make- even though electric drive is basically quite simple, it will never be offered to the public except at a premium. We've been hearing all these years how it's going to be cheaper, etc, but the business of putting transportation into the publics hands is never going to allow that.

Not the least of the concerns is how to charge all these batteries- as has already been stated, the existing and forseeable power generation and distribution systems are not going to be up to the task. And if we take a look at our 'need' to have 2000 lbs of machinery to transport 200 lbs of body around- well, the picture certainly doesn't look good for wide-spread electric vehicle usage.

I dont think the idea here is to save the power generated , but use it immediately to recycle energy fron the exhaust stream straight back into the drivetrain which should allow a lower Specific Fuel Consumption

philbur
05-19-2012, 06:10 AM
But surely you get the compression energy back on a naturally aspired engine. whereas the turbo is feeding itself.

Does a turbo charged engine not require lubricant and coolant.

Phil:)


Much as it takes a substantial amount of energy to pump air through a naturally aspirated engine. How about the energy required to compress the charge in the combustion chamber, pump lube and coolant?

Jaakko Fagerlund
05-19-2012, 08:57 AM
So I end up back at the exhaust combustion --- This is what drives your typical turbo-charger - it's gasses still expanding, it's gasses still being burnt, therefore -
In order to properly understand the turbo charger one has to look at the exhaust between the cylinder head (backside of the exhaust valve) and the turbine for what it is - a secondary combustion cycle. Turbo's do not operate on heat - they operate on pressure, therefore expansion is needed between this space - therefore fuel needs to be burnt in this area and is, Like iv stated before - it's part of doing business with the IC piston engine and having to crack the exhaust valve open even though the combustion stroke is still going on - keep in mind this stuff is happening real fast and we have to get the chamber cleaned out in order to properly introduce the next charge...
Whatta...There is no need to burn fuel in the exhaust under normal conditions, so your logic is a little bit flawed in my opinion.

vpt
05-19-2012, 09:32 AM
Just for giggles look here............ 100mpg

http://afstrinity.com/


Just like the prius and insight that "get the best mileage ever" I have to laugh.

Have a looky at this 20 year old honda: http://www.treehugger.com/cars/modified-honda-crx-hf-wins-fuel-economy-competition-with-118-mpg.html

J Tiers
05-19-2012, 10:05 AM
Darryl..... don't GO there......

Nobody is talking about battery systems at the moment. Please do not get AKB started on hybrids and batteries.... he'll never accept them and that's that.

I WILL say that an exhaust turbine-generator that powered ALL the NORMAL battery charging, power steering, air conditioning, and the various mandatory "Yuppie electrical loads" in a typical gargantuan SUV.... THAT would take a very considerable load off the engine, and by itself could make a substantial overall efficiency improvement.

As for the "cork in the exhaust" BS..... If a turbo when properly designed did NOT improve net power output, NOBODY would put one on a car....or a truck, or a tractor, or a marine engine. But they do, and if you have ever driven a turbo equipped car, along with the non-turbo version, you'd (we hope) understand rather rapidly.

It IS true that if you put in a poorly designed turbo, it might be a loss.

And, it is not "free energy", you only "get" that energy because you made a design choice in making the engine that you are NOT going to try to use the "left over" energy that the turbo uses.

it happens that the turbine is ideally suited to using a larger mass flow of relatively lower pressure, and that it is good for extracting energy that would not be practical to extract in a piston system attached to the same engine operating at the same speeds with the same operating fluid.

AKB is wrong to rule out "power improvements", because any extra power obtained from the 'engine system" without burning more fuel (OR same power by burning less) is a gain.

It happens that often a turbocharger simply improves power per unit volume by cramming more fuel and air (or air for a diesel) into the same cylinder. The fuel per watt of output is not changed in that case, you just get more power from the same engine. That can be a gain also, but not typically much of an *efficiency* gain.

But if heat or other energy content of the exhaust can be used to do some other work, by being connected to the output shaft, used to remove a load from the engine, etc, THAT increases efficiency by actually getting more net power output of the engine system at the output shaft from the same fuel burned.

******************************

The IC PISTON engine is completely unsuited to a major efficiency gain that any Brayton cycle engine can easily use.

In a Brayton cycle (gas turbine), there is continuous flow, instead of the "batch processing" used in a piston engine. So compression is followed by heat input, and that is followed by energy extraction. Each is, or can be, in a separate ares of the device.

There is NO distinction between different sources of heat. So, a Brayton cycle can use the exhaust heat to pre-heat the compressed air, just prior to burning any fuel in it. By recycling that heat into the working fluid AFTER compression, a fairly huge efficiency increase is obtained.

Since the piston engine "batch processes" the air inside the cylinder, it is virtually impossible to add heat between compression and fuel burn, without a complicated system with flow losses etc that make it pretty stupid. There are one or two ideas which "might" help fix that, but it adds complexity.

That is a serious problem with the piston engine. However, piston engines manage to do pretty well without it.

sasquatch
05-19-2012, 10:05 AM
Agree with VPT,, thanks for posting that honda 118mpg pic.

J Tiers
05-19-2012, 10:54 AM
Back in the 1960's I drove a Saab which had free wheeling - when the accelerator was released, sprag clutches on each axle released and the car coasted with the engine idling. It took practice to get used to it, one needed to plan ahead farther for stops (something that still affects my driving). And when picking up RPMs after coasting down a hill one had to do so gently to avoid a thump. One could lock free wheeling out but doing so cut gas mileage by about 20%. Engaging reverse automatically locked it out, else you wouldn't be able to back up ;)


Had one then, and into the 1970's...... 96, and several 95's.

I think the freewheeling is generally illegal now..... stupid. Most people would be totally unable to comprehend how to drive with it. Apparently most people are stupid, AND/OR they are carefully steered away from any true understanding of how things actually work.

You can do the same thing as the freewheeling by just hitting the clutch and shifting into neutral, though.

if you have an automatic tranny, I guess you are just SOL...... :rolleyes: :D

I don't get a huge improvement even if I do fairly extreme coasting.....it is generally drowned out by all the other variables causing "noise" in the data.

Black_Moons
05-19-2012, 11:42 AM
Had one then, and into the 1970's...... 96, and several 95's.

I think the freewheeling is generally illegal now..... stupid. Most people would be totally unable to comprehend how to drive with it. Apparently most people are stupid, AND/OR they are carefully steered away from any true understanding of how things actually work.

You can do the same thing as the freewheeling by just hitting the clutch and shifting into neutral, though.

if you have an automatic tranny, I guess you are just SOL...... :rolleyes: :D

I don't get a huge improvement even if I do fairly extreme coasting.....it is generally drowned out by all the other variables causing "noise" in the data.

My motorised bicycle 'freewheels'. I absolutely LOVE IT!
Every time you release the accelerator it goes quiet like I am idling at a stoplight. None of that BRAPBRAPBRAP engine brake noise, or having to feather the pedal to keep the dang engine brake from kicking in at random.

Willy
05-19-2012, 12:14 PM
But surely you get the compression energy back on a naturally aspired engine. whereas the turbo is feeding itself.

Does a turbo charged engine not require lubricant and coolant.

Phil:)

You missed the point I was trying to make.
The slight lose in exhaust gas flow inherent to a turbocharged engine is part of the cost of doing business.
Much like the parasitic loses due to pumping energy required in filling a naturally aspirated engine, any IC engine also has parasitic loses due to lube and coolant pumps.

A.K. Boomer
05-19-2012, 12:51 PM
Whatta...There is no need to burn fuel in the exhaust under normal conditions, so your logic is a little bit flawed in my opinion.


Jaako, there is a need - in the typical IC piston engine its part of doing business when your trying to get the exhaust moving out so you can introduce the next intake charge,

I think what amazes me most is some peoples inability to grasp that this stuff is happening at the rate of 25 to 50 times per second, what this equates to is when it comes to the combustion cycle you cannot help but throw the baby out with some of the bath water,
Like I stated before -- you need to see the beginning of your exhaust system for what it truly is - a secondary combustion chamber, it's how the turbocharger even operates in the first place....


Like I also stated before -- you want proof of this "concept" disconnect your header and run your engine at load at nightime -- send me back some pics of the two foot long flames shooting out of your exhaust ports... very pretty blue and yellow colors... :)

Like I also stated before - this is what happens when you crack your exhaust valve open under extreme pressures when it's only 2/3rds the way down from TDC of the cylinder bore....

can we move on now?

Willy
05-19-2012, 01:04 PM
Like I also stated before -- you want proof of this "concept" disconnect your header and run your engine at load at nightime -- send me back some pics of the two foot long flames shooting out of your exhaust ports... very pretty blue and yellow colors... :)




I agree some of the baby is thrown out with the bath water, but...

In the scenario above you are also forgetting that you are now introducing copious amounts of free oxygen.

An ingredient not present in the exhaust system/turbocharger to any appreciable extent. There may be some slight quantities of unburnt fuel but precious little free oxygen.
Remember the three ingredients required for combustion must include heat or a source of ignition, fuel, and oxygen.

This is one of the reasons fuel tanks where often welded after being filled with exhaust gas...no oxygen...tank no go boom.;)

danlb
05-19-2012, 01:12 PM
Like I also stated before -- you want proof of this "concept" disconnect your header and run your engine at load at nightime -- send me back some pics of the two foot long flames shooting out of your exhaust ports... very pretty blue and yellow colors... :)

Like I also stated before - this is what happens when you crack your exhaust valve open under extreme pressures when it's only 2/3rds the way down from TDC of the cylinder bore....

can we move on now?


Since this was posted before, I thought about it a bit. This phenomenon is easily explained because you have ZERO back pressure in this configuration. My sedan is not a drag racer. It's not designed to run without headers.

I learned (long ago when tuning a car was important to me) that the back pressure should be considered part of the valve timing. Proper timing of pulses from adjoining cylinders keeps the fuel rich intake charge from being blasted out during that moment of overlap when the exhaust is still closing and the intake is opening. Too little back pressure and you end up with backfires as fuel in the exhaust system ignites.

To really prove the point that there is combustion going on, simply drill a hole in the header and install a quartz window. It should be pretty obvious that whether there is combustion going on inside the header. Anyone done that? Should be able to find a youtube video if they have.

Dan

A.K. Boomer
05-19-2012, 01:26 PM
Darryl..... don't GO there......

Nobody is talking about battery systems at the moment. Please do not get AKB started on hybrids and batteries.... he'll never accept them and that's that.


JT - don't put words in my mouth please --- I give plenty of credits to the almighty hybrid system where credits are due and that's in the form of synergy drive and as we all know that takes batterys... Iv said it before and i'll say it again, hybrids make allot of sense in the city all because of being able to harness energies that would otherwise just go to heating up your brake rotors and drums...



As for the "cork in the exhaust" BS..... If a turbo when properly designed did NOT improve net power output, NOBODY would put one on a car....or a truck, or a tractor, or a marine engine. But they do, and if you have ever driven a turbo equipped car, along with the non-turbo version, you'd (we hope) understand rather rapidly.

JT --- this is an unfair comparison and it's why I tried to separate the "power" argument from the "efficiency" one

But - it's a good example to roll with so here we go, you cannot compare the net gains on a typical turbo gas engine to have anything to do with efficiency and in fact they eat it bad - they are the worst fuel hogs we have...
The reason your making so much more power is the intake side is being compressed - and the intake side is the dominant valve by far, what goes in WILL come back out no matter the price...
this extra "power" is not to be confused with efficiency...



AKB is wrong to rule out "power improvements", because any extra power obtained from the 'engine system" without burning more fuel (OR same power by burning less) is a gain.

Im not wrong at all -- your statement is exactly what I stated earlier, and it does not have to be "more" power -- it can be the same as long as less fuel is being burnt to achieve it... It can even be less as long as the amount of fuel being burnt is far less...
if your going to try and nitpick and waste peoples time then at least get the facts straight


It happens that often a turbocharger simply improves power per unit volume by cramming more fuel and air (or air for a diesel) into the same cylinder. The fuel per watt of output is not changed in that case, you just get more power from the same engine. That can be a gain also, but not typically much of an *efficiency* gain.


Your wrong - it's nowhere near that simple esp. when it comes to the gas IC engine --- all kinds of things have to be considered and the most critical is the fuel air mixture when your effective compression ratio goes up due to packing in another half of atmosphere - richer mixtures HAVE to be utilized or holes in pistons will soon develop from pre-ignition and detonation...

the fuel per watt output IS changed.

It's part of the reason why typical turbocharged gas engines are so damn bloody inefficient....
unless your talking direct injection gas - they can avoid much of these pitfalls and get by with a more suitable mix for efficiency.







But if heat or other energy content of the exhaust can be used to do some other work, by being connected to the output shaft, used to remove a load from the engine, etc, THAT increases efficiency by actually getting more net power output of the engine system at the output shaft from the same fuel burned.

Yes - total agreement, ;)





******************************

A.K. Boomer
05-19-2012, 01:41 PM
To really prove the point that there is combustion going on, simply drill a hole in the header and install a quartz window. It should be pretty obvious that whether there is combustion going on inside the header. Anyone done that? Should be able to find a youtube video if they have.

Dan


While a set of glass headers would be cool :) I don't think we need to go that far,
all that one needs to know is that the exhaust valve is cracking open during the combustion process ---- this cannot be disputed - all one needs to do is google some exhaust valve duration charts, all engines vary some - the more radical and higher RPM the earlier they have to crack them open,

Catalytic converters need oxygen to function, it's why we have oxygen sensors just before them and just after -- and they are way downstream from a turbo charger --- they need a certain amount of free oxygen going into them to consume what's left of the unburnt hydrocarbons,
Willy said it best - no oxygen no boom...

A.K. Boomer
05-19-2012, 02:19 PM
Why are we even discussing this?

if you guys are having trouble with still expanding combustion gasses spinning a turbine and im giving you all these proof positive examples as to how it gets it done then if you feel this is wrong somehow please let's flip the coin around and tell me how a turbocharger spins off of just heat that's cooling off rapidly with no expanding pressure -

This is what your telling me - that all combustion is gone and it's just heat that's rapidly cooling off driving the turbine,
Do you know how flawed your thinking is - if all combustion was spent in the chamber then the gasses would actually be cooling and RAPIDLY contracting on the way out --- might not be a bad idea if you want to spin the turbine backwards...

I can guarantee you ahead of time we can put an entire unit in the oven and turn it on high and the turbine will just sit there and will not rotate...

Turbo's operate off of pressure - and heat is part of this process - and the heat does not stop dead inside the combustion chamber, and neither does the pressure, therefore fuel is still being burnt outside the chamber --- remember guys 25 to 50 times in one second... am I reaching you?

Ok - flipping things around - lets hear your explanation of how an exhaust turbine on a turbocharger works...

come on - who's going to pick up this torch and run with it...

and then I'll critique it:)

then after we get some of these basics out of the way maybe we can move on to gains and losses of the OP...

A.K. Boomer
05-19-2012, 02:36 PM
I dont think the idea here is to save the power generated , but use it immediately to recycle energy fron the exhaust stream straight back into the drivetrain which should allow a lower Specific Fuel Consumption


Exactly --- and again the reason I chose the hybrid as an example is that it already has systems in place to possibly make it the best recovery system example ever --- By already having an electric motor to dump the power from the gen directly into...

and the amount of turbine control would be incredible --- by computer controlling the fields on the gen you directly control turbine load for maximum RPM efficiency - couple that to a computer controlled waste gate all working with most of the engine sensors already installed - it would cut through allot of mechanical crap we had to go through in the past examples...

danlb
05-19-2012, 03:02 PM
Why are we even discussing this?


Turbo's operate off of pressure - and heat is part of this process - and the heat does not stop dead inside the combustion chamber, and neither does the pressure, therefore fuel is still being burnt outside the chamber --- remember guys 25 to 50 times in one second... am I reaching you?

Ok - flipping things around - lets hear your explanation of how an exhaust turbine on a turbocharger works...



I suspect that AKB is the only one suggesting that the turbo runs off of heat. The rest are content with the normal explanation... the turbo is spun by the moving gases pumped by the engine as the exhaust stroke.

See for more info: http://auto.howstuffworks.com/turbo1.htm

The turbo is only providing 6 to 10 psi at about 120 cu ft per minute (1.7 liter at 2000 rpm). It does not need a huge amount of power to do that.

Dan

A.K. Boomer
05-19-2012, 03:15 PM
I suspect that AKB is the only one suggesting that the turbo runs off of heat.

Dan


Dan, all due respect -- how in the hell can you possibly arrive to that conclusion when its exactly the opposite of what iv been saying?

how? how can you be that far off base?

did you just miss the part where I said "put one in an oven and see if it rotates" did that just wing right over your head? :rolleyes: this is futile...

A.K. Boomer
05-19-2012, 04:23 PM
The rest are content with the normal explanation... the turbo is spun by the moving gases pumped by the engine as the exhaust stroke.

And for the record this is not the normal explanation - it's the one given to people who look stuff up on "howstuffworks".

the turbo is spun by expanding combustion gasses - it's not spun by using the engine as a pump,,, this of course WOULD fall into the "overunity" BS

To prove this point drive a turbo diesel down a hill and let off the throttle --- what's your boost gauge show? don't know? I'll tell you - ZERO, yet it does not have a throttle plate so is wide open throttle and the waste gate is totally closed -- now - tromp down on the throttle and add some expanding gasses and therefore pressure, walla 8 lbs staring you back in the face...

If you think you can somehow achieve boost by moving the same volume of air past the exhaust turbine that is being used to compress the intake side then you have joined the overunity crowd...



The turbo is only providing 6 to 10 psi at about 120 cu ft per minute (1.7 liter at 2000 rpm). It does not need a huge amount of power to do that.

Dan

Ever check into what it takes for a car to be driven at lower highways speeds?

Willy
05-19-2012, 04:27 PM
Wish I had more time to get into some of the more esoteric nuances that go into turbocharger theory AK but I have to run because I have a whole s**tload of stuff on my plate today.

In a nutshell turbochargers rely on pressure differential across the inlet and outlet side of the turbine in order to spool the turbine up to a useful enough speed to do work.
Heat of the incoming gas has of course some effect. This is why quite often you will see thermal wrap on the manifold leading up to the turbo and or a short as practical manifolds to the turbo.
The biggest factor though is exhaust gas velocity. Small inducer, large exducer equals pressure differential, this in turn equates to turbine speed.

I'll check back later tonight or tomorrow to see if anybody needs a spanking.:D

Black_Moons
05-19-2012, 05:12 PM
Wish I had more time to get into some of the more esoteric nuances that go into turbocharger theory AK but I have to run because I have a whole s**tload of stuff on my plate today.

In a nutshell turbochargers rely on pressure differential across the inlet and outlet side of the turbine in order to spool the turbine up to a useful enough speed to do work.
Heat of the incoming gas has of course some effect. This is why quite often you will see thermal wrap on the manifold leading up to the turbo and or a short as practical manifolds to the turbo.
The biggest factor though is exhaust gas velocity. Small inducer, large exducer equals pressure differential, this in turn equates to turbine speed.

I'll check back later tonight or tomorrow to see if anybody needs a spanking.:D

Exactly right. The only thing I would like to add is:

Turbo chargers use more fuel at WOT because they add more intake air and that means more fuel is used to bring it back to the correct mixture ratio. They do not make a engine any more efficient on the same amount of fuel, they make it a 'bigger' engine by increasing its effective displacement by craming more air/fuel mix in.

Heat is used to keep the gases expanded. Expanded = more volume. the whole idea of an IC engine. thats the only roll heat plays for turbines.

Extracting energy from exhaust in the form of pressure differential causes.. a pressure differential, hence a restriction, A restriction on the outlet of an air pump requires power.

Thus the question is not "Can you extract power from the exhaust pressure * flow ", You most certainly can.

The question is "Can you extract power from the exhaust pressure * flow more efficiently then the piston engine itself can?"

Thats why extracting energy from the heat of exhaust is more tempting then extracting the pressure differential * flow energy you can achieve by restricting the exhaust, because to extract the heat you do not need to burden the engine with higher exhaust pressures that will exactly equal the amount of energy extracted. The pressure still has to escape to ambient to prevent burdening the engine. The heat however is done with.


Heres an idea for you: What you do is take a turbo, but instead of putting an engine in the middle, you put a heat exchanger to the exhaust of the engine.

Your heat exchanger does not have to heavily restrict air flow to extract heat, And heat energy will expand the gases on the turbo side of the heat exchanger causing it to spin up. You can then couple an alternator to the turbo charger shaft.
(Alternative idea for higher chance of success without loss of engine efficency: Steam turbine/piston engine, With a exhaust header thats built with water channels around the normal walls of the exhaust hence absolutely no introduced restriction)

Question again becomes: Is it worth it, Can you do it without too much weight and cost?

A.K. Boomer
05-19-2012, 05:20 PM
Wish I had more time to get into some of the more esoteric nuances that go into turbocharger theory AK but I have to run because I have a whole s**tload of stuff on my plate today.

I have a little free time today before I go ride my bike - so allow me to help you with some of your misguided esoteric nuances...:p


In a nutshell turbochargers rely on pressure differential across the inlet and outlet side of the turbine in order to spool the turbine up to a useful enough speed to do work.
Heat of the incoming gas has of course some effect. This is why quite often you will see thermal wrap on the manifold leading up to the turbo and or a short as practical manifolds to the turbo.


perfect - your actually doing very good so far


The biggest factor though is exhaust gas velocity. Small inducer, large exducer equals pressure differential, this in turn equates to turbine speed.

Ooooooooops - someone just joined the overunity crowd - collect your dunce cap on the way out and your box of fake crayons on a leash that you can't swallow - ;)

first off you can't just make power from downsizing your plumbing - and in fact that just creates friction and drag - you need a driving force first - so you skipped the main driving force of the turbocharger and that is expanding gasses - the turbo lives off of them - it is right in the midst of a secondary combustion process plain and simple It's WHY you see insulated pipes sometimes - it keeps the efficiency up due to not allowing contraction of the super heated super pressurized combustion gasses the same way ceramic coatings on internal engine combustion chamber parts get more pressure to the piston - it's because they don't allow for heat retraction of the gasses --- if you cannot grasp this concept then you will never know the proper theory of operation...

That's how you get exhaust gas velocity in the first place - THEN because the individual ports are only operating at approximately 1/4 the time you bet your sweet bippies you need to downsize your piping immediately after to keep the velocity AND pressure up... :D
that's what you can do with knowing proper theory of operation.

according to you the turbo diesel would still make copious amounts of boost even with your foot off the gas on deceleration just because your increasing the velocity past the turbine, not how the real world works Willie...

you have to add combustion - you have to add expansion, without it the turbo is inop. because without them pressure differential is virtually non-existent...





I'll check back later tonight or tomorrow to see if anybody needs a spanking.:D

Oh ok Willie... I'll be sitting on the edge of my seat.

Jaakko Fagerlund
05-19-2012, 07:22 PM
The turbocharger doesn't need any fuel burned between it and the cylinder (in the exhaust basically) for the turbo to operate, period. If it would, you would have fuel injection in the exhaust.

Lets see: you put X amount of air in the cylinder and Y amount of atomized fuel and then ignite it. What is the volume of that after even a partial combustion? It is not X+Y, but very much more, so that is where you get the driving force for the charger: the expanding (/expanded) gas. It doesn't have to expand by burning after the cylinder for a turbo to operate, but as you have said AKB, in real life it does still burn to some extent outside the cylinder. However, it is NOT required for the operation of a turbo.

MrFluffy
05-19-2012, 07:53 PM
I agree. Hopefully by the time its in the downpipe, the gas is already almost completely combusted since the flame front propogates from the top of the head therefore the valves will be excavating the burnt gases as the lowermost section of the burn still is going on at the lower part of the power stroke, assuming aggressive exhaust valve timings. To help the cfm's there's some expansion of spent gases as they cool when they hit the manifold which is why its good to have the turbo close to the valve to avoid heat loss to the air, and have the expansion take place inside the downpipe or the housing of the turbo instead.

There is a system designed to burn post valve, the old ALS or anti lag as used in rally and drag racing circles. They basically dump huge amounts of fuel into the engine that doesn't completely combust because the ignition has been retarded a huge amount and there isnt sufficient time for the combustion due to its late starting, and the burn continues when the exhaust valve opens and uses the downpipe as a extension of the combustion chamber. The rapid expansion and explosion there spools the turbo again quickly, at the cost of a really poor turbine lifespan, wrecked headers and other highly detrimental effects.
If you ever followed rallying and heard the cars going bang bang on lift off, that's the anti lag system kicking in.
A friend is involved with a drag bike with ALS, they hold it on the als on the line, and launch with a button with the turbo already spooled. It sits there in the traps banging and popping away but its highly effective. My dragbike build has a supercharger compounded into the turbo to achieve the same thing.

We're digressing, I don't think there's anything to be had by a turbo driving an ancillary system instead of charging the intake. And a turbocharged diesel is quite a gain in efficiency and economy over a n/a motor already.
There are gear driven turbo's (gator's...) so making one in reverse would be feasible but I think the economy would be killed by mechanical losses.

If you want to look at a interesting motor from a efficiency point of view, look at the mazda millenium, it runs a miller cycle engine which is very efficient but a poor performer from a power point of view. They supercharge it with a lysholme screw type compressor to recover some of the lost performance and it still manages to be a efficient little engine. One of them coupled up to a hybrid setup is a interesting concept...

justanengineer
05-19-2012, 08:07 PM
Ooooooooops - someone just joined the overunity crowd - collect your dunce cap on the way out and your box of fake crayons on a leash that you can't swallow - ;)
.

I would suggest you get sized for said cap Boomer. Where do you see energy being created in the system as Willy explained? He explained it correctly btw.

Hot (full of energy and big on volulme) exhaust gas (combination of fuel + air) contains both more energy and mass than cool intake air alone. The turbine flows more than the compressor for these exact reasons, plain and simple, thus no need for outside energy in the form of external combustion.

darryl
05-19-2012, 09:24 PM
Let's see if I got this right- exhaust gas leaving the cylinder blows through the turbo and out the pipe. The turbo has to withstand the heat, but doesn't convert any of it into recovered power. It simply takes some of the inertia from the exhaust and turns that into power. In doing so it creates a bit more back pressure than might otherwise be the case. Increasing the back pressure means the engine has to give some of it's power up to keep the exhaust flowing out.

At the same time, if there's any further burning in the exhaust, that will increase the inertia in the gas flow and the turbo has a chance to recover some of that. As the gas cools, the inertia in the stream lessens, so it's good to maintain the temperature until the exhaust gas has left the turbo.

Without the turbo (or a blower, but we're talking turbos here) you can't increase the power output capability of the engine because you will reach a point where you can't get any more air into the engine. With the turbo you can get much more air through the engine, thus can burn more fuel and produce more power. This will create more exhaust gas flow and will give the turbo more input. A point will be reached where the engine components can't take the increased temperature and pressures, and that will define the level of power available from the engine.

Because the engine can be smaller for the same power output, it will have less internal friction, and it can also be operated at a higher average loading. With luck (or through design) the turbo will draw more power from the exhaust gas flow than the engine has to provide to keep that flow going, and also less power from the engine than is saved through the use of the smaller engine. The result is increased efficiency over a wider range of operating conditions.

darryl
05-19-2012, 09:43 PM
Going back to the title- 'to build a better hybrid'- it would seem to me that the optimum system for efficiency is going to be at odds with our acceptance of that system. Things cutting in and out during a drive, engines turning at rpms that don't seem to match the vehicle speed, engines starting and stopping during the drive- for want of better wording, I'll call this the consumer acceptance factor. It will be a definite factor in sales of such vehicles, so it's definitely going to be a factor in the manufacturers design of the vehicle. IF they were to leave that factor out, what would or could they do to improve the efficiency of the latest designs?

Thruthefence
05-19-2012, 10:45 PM
Run it for awhile without headers, and see what happens to your exhaust valves.

A.K. Boomer
05-19-2012, 11:50 PM
I would suggest you get sized for said cap Boomer. Where do you see energy being created in the system as Willy explained? He explained it correctly btw.

he's way off base --- and so are you --- you guys are actually funny to me :p
Both you and Willy act as if there's a micro switch installed on every exhaust valve that tells the combustion chamber to stop combusting the split millisecond the valve opens - lol and then according to Willy there's a little spritts of halon added right at the backside of the valve to consume any leftover oxygen - this ensures there's not enough oxygen to continue the burn -- yet up to three feet later the oxygen miraculously reappears (from the oxygen fiery of course) and combustion takes place yet again in the glowing red hot catalytic converter --- wow - the turbo world according to Willy and the gang:rolleyes:



Hot (full of energy and big on volulme) exhaust gas (combination of fuel + air) contains both more energy and mass than cool intake air alone. The turbine flows more than the compressor for these exact reasons, plain and simple, thus no need for outside energy in the form of external combustion.


Hello -- news flash - its called combustion gas - and it's going on long after the combustion chamber --- one more time, THE EXHAUST VALVE IS OPENING UNDER COMBUSTION sometimes more than 50 times a second!

is there anything in that statement you do not understand?

let me repeat it one more time just to make sure you hear

THE EXHAUST VALVE IS OPENING UNDER COMBUSTION.

did you get that,,, or is there still some kind of imaginary line drawn in your head at the valve seat or something - lol
any kind of a light bulb going off? anything? maybe even a hillbilly thought as to why we need things called mufflers?

Do you have any idea what kind of trade-offs camshaft engineers are up against duration wise when trying to milk the most out of a power stroke yet at the same time open the exhaust valve WAY early to get the gasses on there way out WAY before the piston is even coming close to BDC? any idea?

Im here to help you with the basics -- but if you act like you know them when you obviously don't you will get a spanking...

the same expanding combustion gasses that are pushing your piston down and therefore your phat little arss down the highway are also responsible for driving your turbine - plain and simple. I don't care if you like this fact or not - deal with it.

Now - PM me your head size so we can get you fitted, it's ok you don't have to tell me in front of everybody... im thinking really small???:p

J Tiers
05-20-2012, 01:11 AM
The point is NOT, repeat NOT whether or not there is any fire in the charge when it hits the exhaust.

I suspect there isn't any particularly, but there IS unburned fuel at a temperature above ignition temp.... That's how the CAT works..... there has to be something burnable in the exhaust or the CAT cools down and won't work anymore.

The point is that there is no need to burn extra fuel in order to GET combustion between the cylinder and turbo..... there is already pressure there, and the turbo works on pressure.

Once it starts to supply higher pressure input, there is also more high pressure exhaust to go along with it.... so the turbo works better. It really isn't any different in basic concept from having a power turbine after the compressor turbine, in a gas turbine.

J Tiers
05-20-2012, 01:25 AM
if your going to try and nitpick and waste peoples time then at least get the facts straight
Your wrong - it's nowhere near that simple esp. when it comes to the gas IC engine --- all kinds of things have to be considered and the most critical is the fuel air mixture when your effective compression ratio goes up due to packing in another half of atmosphere - richer mixtures HAVE to be utilized or holes in pistons will soon develop from pre-ignition and detonation...

the fuel per watt output IS changed.

It's part of the reason why typical turbocharged gas engines are so damn bloody inefficient....
unless your talking direct injection gas - they can avoid much of these pitfalls and get by with a more suitable mix for efficiency.
Yes - total agreement, ;)





******************************

Actually I was thinking of DIESEL........ Gasser turbo gives power, but as you point out, at a cost.

I don't think there are "facts wrong" here in that respect.....

Besides..... there is a difference between the practicalities of a specific case, and the "general case"....

If you start with a low compression engine, and put on a turbo that brings it up to a high but relatively standard compression, say 10.5: 1 (I had a very sedate Volvo wagon that had that ratio w/o turbo), then you ought to be able to run fine by using higher octane gas, just as if you had that ratio to start with.

if you go way high, you either use very high octane gas, use water injection, or you run it rich enough to keep the pinging down.... with otherwise standard engines. I don't know enough about direct injection gas engines to discuss that end of it.

Diesel.....with more air, you can inject more fuel and get a higher power at the "smoke limit" (point at which the oxygen is essentially all used up by fuel). The effect on the fuel rate per watt is relatively small, as I understand it.

vpt
05-20-2012, 11:54 AM
I have a couple things to say. :D

Tailpipe turbos. Way way away from "expanding exhaust" and work just fine.

http://images.chevyhiperformance.com/techarticles/148_0502_turbo_02_z.jpg


Compound turbos.

http://i68.photobucket.com/albums/i17/paulvolk/twinturbo_large.jpg


That is all for now. ;)

danlb
05-20-2012, 02:41 PM
perfect - your actually doing very good so far Ooooooooops - someone just joined the overunity crowd - collect your dunce cap on the way out and your box of fake crayons on a leash that you can't swallow - ;)



You really need to figure out what "overunity" means.

Extra energy is introduced to the engine as extra air and extra fuel. The normal amount of air is already sucked in by the large positive displacement pump you know as the engine. :) The turbo just adds a bit more air so the fuel system can add a bit more fuel. The extra air flow spins the turbo a little faster, and the cycle repeats.

It's the extra fuel that provides all the power.

Dan

Thruthefence
05-20-2012, 02:50 PM
Are any of you guys old enough to have threaded a spark plug into the exhaust pipe of an automobile, and wire it to one of those war surplus crank magneto telephone boxes?

Drive along, pull the choke out a bit, turn the crank, and watch the "afterburner".

A.K. Boomer
05-20-2012, 03:12 PM
You really need to figure out what "overunity" means.

Extra energy is introduced to the engine as extra air and extra fuel. The normal amount of air is already sucked in by the large positive displacement pump you know as the engine. :) The turbo just adds a bit more air so the fuel system can add a bit more fuel. The extra air flow spins the turbo a little faster, and the cycle repeats.

It's the extra fuel that provides all the power.

Dan


Once again you leave out the prime driving force - gas expansion,

Like I stated earlier - take a turbo diesel down a hill @3,000 rpm's and lift your foot off the accelerator --- what does your boost gauge show? allow me to answer that for you - zero.
why? the engine does not have a throttle plate - so it's taking in a full charge of air - the engine is pumping --- where's the boost Dan?

you and many others are leaving out the prime mover of the turbine - gasses that are expanding many times over their original volume...

If you think you can use the engine as a "pump" to then spin a turbine to then spin a compressor to then add boost to the original engine displacement then guess what? youv just joined the overunity crowd also...

maybe we can just have these things humming away in our basement and never pay another electric bill --- then after that maybe a bunch of golden monkeys will fly out of everybody's butts and nobody will ever have to work again for as long as they live --- say it's so antie M - tell me it's true:rolleyes:

ikdor
05-20-2012, 04:47 PM
I don't think there's anything to be had by a turbo driving an ancillary system instead of charging the intake. And a turbocharged diesel is quite a gain in efficiency and economy over a n/a motor already.
There are gear driven turbo's (gator's...) so making one in reverse would be feasible but I think the economy would be killed by mechanical losses.


Don't they use an exhaust gas turbine to drive the crankshaft directly in trucks? It's called mechanical turbo compounding here in Europe.
See somewhere down this page
http://www.heat2power.net/en__benchmark.php

The BMW steam energy recovery is also on that page.

Igor

A.K. Boomer
05-20-2012, 05:41 PM
Wow Igor that's a pretty involved design,

it does make me think there are tons of new idea's right around the corner,

What do you think about this, we start off still with the hybrid, and we either use a turbo direct injection gas or a turbo diesel to have a good start on over all engine efficiency - but here's the catch, they are only about half boost turbo's --- enough to recover the losses from exhaust restriction and add a little umph to the engines performance whilst still keeping it smaller displacement --- but here's the other catch,
it's a full blown exhaust turbine that's only powering a very small compressor one - so it has lots of extra spare energy to harness and here's yet another detail , the unit has no waste gate ---- it uses a generator attached to the smaller compressor turbine and this is what keeps the unit from overboosting is the gens computer controlled drag monitors that control field windings - So you get an almost immediate 4 or 5 pounds boost then all the extra energies are taken from the gen and dumped immediately back into the hybrids electric motor, so since this is all happening simultaneously less throttle equals same results ...

Willy
05-20-2012, 06:50 PM
AK I give up. I mean I totally give up trying to communicate with you. I may as well be addressing a fence post.

I'm tired of going to the effort of posting responses only to have you distort anything I say to fit your agenda. You have an inane knack for making up total distortions of any point that doesn't fit your perceived concept of how things should work.

Not only this but your ability to glean info from members posts are limited to whatever fits your particular agenda of the day.



Wow Igor that's a pretty involved design,

it does make me think there are tons of new idea's right around the corner.........


Comments like this leave me wondering why I bother to post a response to your threads. Not only have I already posted in this thread about Detroit Diesel's compound turbo technology but I also discussed Cummins' Rankine Cycle waste heat recovery system due out soon. I'm sure you are very familiar with both as you did not see any need to comment on either one when I posted about them.

Do you even bother to try and digest any of this or do you just cherry pick items to distort and disregard anything you see fit?
We've been through this before AK were I've laid out evidence and links from every major automotive engineering group in the world only to have you either refute that as nonsense or you chose not even bother reading the evidence.
For instance in another thread you stated that cylinder heads with integral exhaust manifolds were a total engineering fiasco. Even though every major automotive engine manufacture is now making engines this way. I believe this trend was led by your beloved Honda who has been making literally millions of very successful V-6 engines this way since 1996-97.

So yeah, not angry at all, just very disappointed.:(

A.K. Boomer
05-20-2012, 07:47 PM
Willy - sorry but it's hard for me to take you serious sometimes when you pass right by the basics --- your the one who set the trend for this not I - your the one who cannot accept the fact that there are burning combustion gasses blowing past the exhaust valve in a fury the split second it opens,

You got fixated on this and here we are so many pages later:rolleyes:

all while we could have been talking about the OP but instead I had to spend my time schooling people on the basics of turbo charger function -- now that's it's slapping you in the face you want to change the course once again,,,
and bring up integral exhaust manifolds --- give them about 20 years in major production and lets talk after their all crumbling and engine life is documented as being shorter,,, run a little low on coolant and instantly scrap the mill, Bad Idea, and not everyone is following - that's laughable... whatever:rolleyes:

You give up once again Willy cuz you lost the debate and were proven wrong, open mouth - insert foot...