Newbie pitch

[theunchosen]

So I am new to the eco-modding forums, and I have a pitch.

Essentially The largest problem with ICE is that 60% of your converted power leaves the engine unused. Actually, this is the problem with all engines, you lose power somewhere you don't mean to. Unfortunately there is no beautiful mechanical method to scavenge this heat energy that goes out the tailpipe and off the engine block, otherwise we would probably have it OEM.

This is where the hybrids come in. Hybrids are more efficient because they are capable of reclaiming energy in places that ICE cannot. For instance there is virtually no way to reclaim power out of braking in an ICE, but hybrids can do it just fine. Ultimately hybrids are more efficient because they are designed with less aggressive engines and fuel maps to conserve fuel rather ego. Also mechanisms for turbocompounding are not very effective because of complicated gearing that must go into connecting a turbine from the exhaust to the drive shaft.

A possible solution exists, not that its good or feasible, but its there. An old engine given a new chassis and guts has become the hottest new toy in commercial energy production, The Stirling. Stirling Energy Systems(SES <http://www.stirlingenergy.com/>) has manufactured a stirling engine that comes close to its ideal max. You can look at their system but in the short they take 700 degrees from focused sunlight and produce electricity through the stirling engine.

Its just under the size for a 400cc engine to produce their "25 KW"(33 horsepower), which is impressive considering my 1.5 outputs a weak 101 in comparison(good for fuel economy but weak because equivalently sized stirlings could crank 130 hps). Like a true carnot engine the stirling takes a long time to spool up and respond to temperature change(unlike your gas pedal) so its out to juse burn gas and let the stirling take over.

To the proposal.

Rip out the trans(saving some energy from mechanical losses and heat), route the engine shaft into a generator(losing some energy to conversion(heat, magnetic fields, blah, blah) powering your car with two electric motors half the horsepower of your original(smaller engines attached directly to the wheel evade drive shafts and their associated weights and energy losses(or four engines 1/4 original horsepower)). Attach Stirling engines downstream along the exhaust pipe(not the same size as the 4x95cc SES, probably smaller and 3-4 of them) and after the initial spool up of the stirlings you recover nearly 60% of the energy your burned gasoline gives off instead of sub 30% in standard ICE. A problem yet unsolved by mechanical means is how to reclaim or prevent losses while at idle. Unless the engine is cut off it is wasting enormous amounts of energy(virtually all of it, excluding any energy converted for headlights or brakes). Also it avoids the expensive and heavy hybrid batteries. Instead of 500 lbs of batteries just add one or two to the trunk to reclaim solar, braking and idling electricity.

Obvious downsides
removed parts will not outweigh stirlings, generator assembly and batteries.
Minimal if any economy gain for the initial spool up time
Probably more that I've thought of but its late and I'm tired(I'm sure there are plenty I haven't thought of and will soon hear).

Bonuses
Could drop engine size for improved fuel economy because the stirlings would boost HP after they warmed up on the hotside(however long it takes your car's exhaust pipe to burn you)
Could recover electricity from regenerative braking and solar if your car is parked during the day.
Could remove components of the car that are heavy, expensive and break.
Instead of having complicated CV joints for FWD could use less complex more reliable(comfortable) joints since the power could be generated on the other side of the joint.
All ICE improvements to efficiency are added bonuses i.e. HCCI, turbocharging, lean burn
Does not involve an enormous increase in weight for hybrid batteries,fuel cells or "weighty" objects
Could jump overall car efficiency from 30% to 60%.

[NeilBlanchard]

Hello,

There are internal combustion engines that are 2X as efficient (~39.5%): Revetec Homepage

Revetec trilobate engine

[theunchosen]

After reading through the trilobate forum, and some(didn't have time for all the revetech page this morning) It seems like the X bloc idea has advantages. However, it also seems that having a much more efficient ICE does not really affect the above proposal. The trilobate would reduce heat soak through the engine block because its not causing greater friction to get the power out of the cylinders. Also it seems it's going to save heat soaking simply in the two stroke fashion, because the metal can only absorb so much heat so quickly.

That said as long as the exhaust is hot, and I do suspect it would be even after being sprayed(or line the stirlings up first and insulate the pipes to avoid heat exchange with anything other than the stirlings put the (NO)X spray on the otherside and give it a run) and the stirlings would still have a scavenging ability.

[theunchosen]

<edit>
Engine output with 40% efficiency out of the engine would still put 30-40% out the tailpipe and 20-30% radiated from the bloc itself.
If you can recover even 20% of either(or both!) you gain a 50% fuel economy boost. Even if ICE gets to 50%, you could still recover 25% of the lost heat and gain a 50% boost in economy and still be well under what stirling engines are capable of today.

[jamesqf]

I think it's a great idea! Of course, I thought it was great when I had it, 4 or 5 years ago :-) And it was great when GM had it, back it the late '60s/early '70s - do a search on "StirLec".

The problem is that in the past Detroit could always get by by slapping new sheet metal on old bodies - whether it's tailfins or a station wagon on a truck chassis - and spending a bunch of money on marketing.

[theunchosen]

I knew I wouldn't have been the first(obviously I'm not even the first here, oh well).

But the more I consider this idea the better it gets. Using electric motors attached directly to the wheel you evade, axles(why not just use the frame, doesn't have to carry mechanical action anymore), differentials and engine piping or whatever can flow unimpeded by the drivetrain components.

Not that those components really weigh a ton(although both axles combined would by far more than some of the "hair-splitters" posted here, like removing windshield wipers), but they do steal substantial percentages of engine power in their uniform acceleration as well as any and all translation points where power would be lost to heat and grinding.

Although, I said solar would be helpful. . .If I coated the entire top of my car in solar panels I could get maybe 1 horsepower. . .for 900 bucks. Thats not worth it(unless I'm piggy-backing a steady tractor-trailer and still getting sun). Although, If you were going to do it, you couldn't really hurt anything scavenging more electricity.

I'm stuck sitting on my hands because I can in no way manufacture a stirling light enough and efficient enough to package somewhere along the exhaust that would make reasonable power gains.

James I tend to agree, but most of the people on here don't think like detroit. I would imagine we are all in the aptera crowd lol.

But when that vehicle is already available and gets ridiculous gas mileage why compete. Maybe since SES and Aptera are both Ca. corporations they would get together and boost the Aptera hybrid to something even more ridiculous like 500 mpg. . .

I could drive for weeks on a gallon(I only drive 2-3 mi a day lol)

It also allows you(if you're running it in the city) to stay in the low range rpms of the ICE where you achieve greater fuel economy anyway(bad news for HP-types). For that matter. . .you could just run the engine at its peak power/fuel consumption rpm most of the time and vary how much load you pull from it(not really all the time but way more often than we can with current setups).

[some_other_dave]

My question is: How much do you think a transmission and driveshafts weigh? At a ballpark, figure 75 lbs for a small-ish car like my CRX or a similar-year Civic.

Now, add two hub motors. What do those weigh? I'd guess more than 25 lbs each. You will need batteries to hold the electrical power you are generating. Maybe not as much as a hybrid uses, but probably not a lot less. Figure (going small) 50 lbs for batteries. And how much does a Sterling engine weigh? I don't know, but even if you get one at 10 lbs, you still need the cooling system (which adds weight, a small one might be 10 lbs?), and an alternator (which also adds at least a couple of lbs).

So you have added some waste energy recovery, but at the expense of quite a bit of extra weight. It would be very interesting to see what kind of trade-offs would be involved.

You could downsize the ICE, which would reduce the weight some more. Or you could eliminate it all together, like what was done by GM many years ago or Dean Kamen more recently...

Interesting ideas, though.

-soD

[theunchosen]

-soD(is it ok if I use the acronym to reference you?. . .its alot shorter lol)
You're right I know for a fact you would be adding weight. I assumed you would be essentially adding a secondary engine(in the case when the ICE is not downsized). So it would be a substantial amount of weight.

The SES suncatcher employs a system that is smaller than a 400cc engine. Weight wise who knows? I don't. The parts could conceivably be made from aluminum and then it would be light(lighter than a block of steel. . .) Bonus point no cooling system required(although 10lbs is way under what the stirling would weigh). The engine could be. . .Aspirated?. . .naturally because the engine's system is based off heat difference and heat syncs on open air and even more effectively when exposed to wind created by driving.

To the point, the 400 CC produces 25 KW(33 HP).

Drop Trans 10 lbs additional 10-15% efficiency gain(mechanics of trans are not FE)
Drop Axles 20 lbs additional boost, no wasted uniform acceleration
Drop differentials(front or rear or both depending on car) 10 lbs additional friction gains
Drop CV joints(FWD+AWD only) 2 lbs additional friction gains

These are underestimates. I'm pretty sure the components weigh more so I tried to low ball since I don't have actual numbers(the trans power loss depends on your model but its legitimate).

Add
2(4) engines 50(total or 75ish for four) pounds 5% energy loss in conversion(electric to mechanic)
2 stirling engines 70 pounds 1/4 recovery of lost energy(efficiency of 25%(actual are up to 68% and av is 50%))
1 larger alternator 20 pounds more than old alternator 5% loss in conversion(mechanical-electric)
2 standard batteries 80 lbs

let's assume my Del Sol is the test car.
dropped 42 lbs and gained 200
+158 lbs
added (1/4 of energy input to stirlings(100 hp)) 25 HP
The formula is 1-2% for every 100 lbs(?) so 4%(high-side)
101 hp +25 hp =125 HP
25/101 ~ 25%
25%-4%=21% increase

Gain of 6.5 mpg

This ignores that the alternator, electric motor and electrical wiring is more efficient than. . .Trans, Drive shaft, Axle, Differentials, and finally joints.

a negligible amount of power is lost in the cables and the overall % lost through the conversions would be 10%(equal to the trans of a manual alone).

this also does not account for energy stored in the batteries when coasting(engine on) or traffic stops(engine on). The batteries could come in to play here and get the car through the energy expensive acceleration phase and recharge off the idle and regenerative braking.

Ignoring energy saved in the bats or friction savings if you bump to 50%(17-19% behind SES) my del sol jumps to 52.5 MPG(50% increase). Even the Prius, Camry and other hybrids don't come close lagging 6 mpg behind.

Somehow the Aptera still beats it(I suppose they are doing something similar but with a much lighter vehicle(1500 lbs opposed to 500) better aero frame(drag of only .011 .11 whichever is amazing but not unreasonable(can't remember where the decimal goes ^_^)) and probably is using smaller motors than an equivalent 100 horses.

If you really really wanted to get picky about it. . .drop the aluminum,steel whatever shell you have replace everything with carbon fiber(frame of titanium or aluminum) put 13-14 inch tires on, replace the glass, take out everything that is not drive essential, drop engines to 100hp aluminum engine, add a stirling on the engine block to salvage that other 20-30% sneaking off the block and you could find yourself in Aptera land without the extra batteries or three wheels.

[jamesqf]

Couple of things to think about:

Wheel motors, unless they're awfully light, add considerably to unsprung weight. There'd be other problems too, if doing a conversion. For instance, what do you do if you get a flat? Whereas if you just bolt on an electric motor where your transmission sits now, things are much simpler.

Solar panels on your car = bad idea, at least until they become about as cheap as paint. Your car's going to spend a lot of time in the shade, or parked/driven at non-optimum orientations to the sun, so you'll get much less than their max potential energy from them. Better to leave the solar cells sitting on your roof at home, pumping out watts whenever they can.

[theunchosen]

I agree on the solar thing, but if you were really going to push the envelope its a step(and some manufacturers claim to be getting close to the paint).

It's more simple to swap out the trans for an EM, but then you still have to spin an axle thats 4-5 feet long and several inches in diameter. And the EM's could attach to the wheel the same way your axle does, through the lug nuts. Put it up on a floor jack pop the tire off and screw the heads down tire changed. same as it is now.

The unsprung issue I had considered but had not resolved, and in light of presenting the best argument did not bring it up. I think it was yokohama that was designing a wheel that was not inflated but ran alot like the lunar landers piano wire mesh(although it was aluminum slides). It would allow for the same deflection the rubber tire would give and have a much greater life span. Use the same concept just use thinner sheets or more flexible alloy to give greater deflection to protect the motors. Or combine the two standard tires and the non-rubber part(steel, aluminum, whatever) wheel would have additional flexibility to add deflection.

Or just straight up use rugged motors to start with.

Another plus about the wheels attached to a very short shaft and then the motor is if anyone of them failed the car could easily still reach its destination. It may even be possible for three of the motors to fail and still be able to limp to a service station. If the ICE gave out you would still have some very tiny amount of time stored in the thermal energy in the pipes and chassis around the stirlings and your three total batteries to juice you a very short range(maybe around a few corners into cell range).