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Advanced Course in Hybrid Engineering - READ ONLY

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Messages Page 20 of 21

#187 of 206 External combustion vs. Internal combustion by i842wings

Jun 22, 2007 (3:29 pm)

I just have a question about the use of internal combustion for hybrids and you guys sound like you know what your talking about. Why not use an external combustion (steam) power source to generate the electricity needed for a hybrid car. Aren't they much more efficient. Any know what happened to the Enginion steam cell?

#188 of 206 Re: External combustion vs. Internal combustion [i842wings] by toyolla2

Jun 23, 2007 (1:37 pm)

Replying to: i842wings (Jun 22, 2007 3:29 pm)
Not to put a damper on your suggestion but steam is only useful in the mega scale. I think others who pass here and have been familiar with enthalpy-entropy charts and the 1939 Callendar Steam Tables will concur with that also.
 
Solutions to electric vehicle propulsion have always been subject to wacky ideas. Even car companies like Mercedes Benz which was looking to fit thermoelectric generators on hot exhaust pipes ! Well I guess there was a government tax credit attached so why not let some guys play around ? As long as the outcome is unlikely to change the status quo.
 
All that is really needed is good applications of existing technology. For example when Toyota introduced liquid cooled heatsinks in the Prius I remember thinking that that in itself was fairly exotic technology to employ for a 50KW inverter. The largest single electronic drive I ever commissioned was 300KW (400Hp) and the SCR stack was forced air cooled, so from my standpoint I couldn't see why Toyota would ignore this more bulky but time proven method. In the event liquid cooling has shown that this is the way to go for automobile systems, their failure rate is a thousand times better than I would have predicted they would have received with an equivalent version that would have been air cooled.
 
The idea I proposed earlier, using a single cylinder 450cc engine has received no comments yet but it is a good suggestion for reducing the cost of hybrids. When the engine is fully decoupled from the wheels as in a series hybrid it provides a lot more options in the prime mover. Generally you want high speed because that reduces frame sizes for the same power, but exotic devices like gas turbines have to be precluded because they require expensive high temperature materials and don't perform efficiently at part load. A modern single cylinder design on the contrary may net you 60HP in a small light package and avoid all that, so the resulting hybrid vehicle could actually be lighter than one with a conventional four cylinder with clutch and manual transmission. Not forgetting that with this hybrid you can redline the engine at max torque from a very low speed until you reach your target roadspeed - can't do that with a stepped transmission manual or the auto kind nor can the Prius either until it reaches 50mph. So this 60Hp may behave more like it was 100HP in practice.
 
T2

#189 of 206 Re: External combustion vs. Internal combustion [i842wings] by dhanley

Jun 25, 2007 (3:00 pm)

Replying to: i842wings (Jun 22, 2007 3:29 pm)
"Why not use an external combustion (steam) power source to generate the electricity needed for a hybrid car. "
 
That *might* be possible. The biggest problem with steam is that it takes awhile to get going, so to speak, and if you stop suddenly, a lot of heat might gp to waste. In the case if a hybrid, the electriv motor could move you at first when the steam was being accumulated, and after parked, the leftover steam could top off the batteries.
 
I've had much the same thought in regards to a stirling cycle engine, which is more efficient than steam.
 
BMW is developing a small steam engine driven by the heat of the exhaust, which then assists in driving the car. Supposedly, this increases both power and fuel economy by 15%.

#190 of 206 Re: External combustion vs. Internal combustion [toyolla2] by tpe

Jun 25, 2007 (5:57 pm)

Replying to: toyolla2 (Jun 23, 2007 1:37 pm)
but exotic devices like gas turbines have to be precluded because they require expensive high temperature materials and don't perform efficiently at part load.
 
You are talking about a series hybrid, right? Why would the gas turbine ever have to operate at part load?

#191 of 206 Series hybrid models by toyolla2

Jun 26, 2007 (5:35 am)

TPE, as I stated in my post #186 : -
 
My model does not require an HV battery as either a major storage element or as an element able to deliver major power. In the model I propose, a conventional sized lead acid 12v battery could deliver 900W of power to the HV bus which would suffice for starting and for the type of limited low speed mobility in forward and reverse most often required.
 
Our series hybrid models are quite different. You seem to be a battery storage type guy and I'm not. That means therefore my choice of prime mover will be operating at part load all the time except on steep inclines or when extreme acceleration is required.
T2

#192 of 206 Re: Series hybrid models [toyolla2] by tpe

Jun 26, 2007 (7:05 am)

Replying to: toyolla2 (Jun 26, 2007 5:35 am)
You seem to be a battery storage type guy and I'm not.
 
Not really. I do like performance and the beauty of EVs is that you can have both performace and efficiency. There's no way a 60 hp engine can deliver the type of performance that I'd be interested in unless it was able to charge a more powerful battery pack. I'm not talking about a huge battery, <100 kg would suffice if it was the new type of fast charge/discharge offered by Altairnano or A123 Systems. Yes carrying around this extra weight would detract somewhat from efficiency but if you can more effectively take advantage of regenerative braking then the extra you spent to accelerate the greater mass would be largely recovered. Also, unlike in your system, the engine that was charging this battery would only operate at its peak efficiency, which would further offset the hit taken by the added weight. Interesting concept. http://www.evworld.com/article.cfm?storyid=1277 http://www.velozzi.org/

#193 of 206 Re: Series hybrid models [tpe] by toyolla2

Jun 26, 2007 (4:15 pm)

Replying to: tpe (Jun 26, 2007 7:05 am)
tpe, the thing is not to sacrifice yourself on the Altar of High Efficiency. A BEV needs regen since the battery is the equivalent of a gallon of gas. Else regeneration on a hybrid is way too much trouble to save a cup of gas - you would be doing a heck of a lot of regenning to even do that.
And who pays for the energy lugging that battery round the streets ? And who wants to pay for the battery also ? I've been into that before on this forum, let's not go there.
 
Load levelling for peak efficiency. Talk of peak efficiency always raises a red flag with me. Like a product in a supermart with the word Gourmet on it. Expect to pay double. It's usually the same thing in a fancier box.
 
 So now you've got me turning off my engine while I drain my battery to 10% SOC at which point my engine comes on at full bore ( for peak efficiency of course) to recharge it. I see you bought into this one.
 
Let me ask you some questions. Are you aware of the losses involved churning energy through a battery ? And are you oblivious to the problems of poor mileage experienced by HCH owners when temperatures drop to five degrees C ?
Sure the battery is in the cabin, but the car might be outdoors 24/7. Your 40 minute commute is not going to be long enough to thaw it out.
 
But its not all bad news. Here's a creed I can go with. It was in your EVWORLD article : -
The overriding design strategy for Velozzi is weight-savings and has its origins in high performance auto racing. He pointed out that the lighter the vehicle, the less energy it takes to move it.
 
Exactly ! So no 100kg battery for me. When you've unloaded a 4-cyl together with its clutch and transmission from the engine bay a genuine 60HP with a throttle response second to none won't seem so bad.
 
My whole thrust nowadays is to look for ways that hybrid costs may be reduced. Replacing the HV battery with a 'virtual battery', the elimination of the stepped transmission or mechanical CVT of questionable durability and the adoption of single cylinder 450cc engine technology are definitely on that path. They won't please everybody
but they will be an answer to the rather expensive, bloated HSD system now out there.
T2

#194 of 206 Re: Series hybrid models [toyolla2] by tpe

Jun 27, 2007 (4:40 am)

Replying to: toyolla2 (Jun 26, 2007 4:15 pm)
I guess the main difference between your philosophy and mine is that I view hybrids and plug-in hybrids as an evolutionary step towards pure EVs, powered by batteries, ultra-capacitors, hydrogen, or some yet to be discovered storage device. Your path does not lead in that direction.

#195 of 206 Re: Series hybrid models [tpe] by toyolla2

Jun 27, 2007 (3:50 pm)

Replying to: tpe (Jun 27, 2007 4:40 am)
Could it at least be said we are both of the opinion that electric power is the most efficacious way to drive the wheels ?
We just differ on the source of that power.
 
My suggestion is about proven technology, successful application should be quick, simple and relatively inexpensive.
It's the now.
Energy storage systems of which you speak are not yet proven technology, development will be slow, difficult and expensive.
It's the then.
 
 I will agree that there can be penetration of Battery Electric Vehicles into the market if they come suitably equipped with tunes, A/C and at a reasonable cost, this is not the 'Operation Hairshirt' crowd, I know that. But I question whether any car company has the will to do that today. And it is not encouraging when even advocates like yourself insist on raising the bar as you did somewhat when you preferenced in terms of 60+ HP versions. For that particular upmarket, I can't see vehicles to be available in the short term and they will be expensive unless, as they say, the alchemist shows up and soon.
Case in point, Ballard Power Systems with its fuel cell design, been in existence seems like forever and still not ready for primetime with consumers. Battery technology indeed is difficult.
 
Meanwhile I, on the other hand, propose a back to basics rethink.
 
Here's the amount of electric power we need - say 45KW (60 HP).
Here's the best way (small, lightweight, simple and lowest cost) to generate it - a brushless alternator at 10K+rpm.
And since the alternator is going to need a mechanical drive.
Here's one of the better ways (small, lightweight, simple and lower cost) to drive it - the 450cc big bore short stroke liquid cooled 4 valve single cylinder engine.
 
This is the horse I am betting on. Thanks, nice discussion
T2

#196 of 206 Re: Series hybrid models [toyolla2] by tpe

Jun 27, 2007 (6:22 pm)

Replying to: toyolla2 (Jun 27, 2007 3:50 pm)
I'd be surprised if a 450cc engine could generate 60 HP at less than 8,000 RPM. What would that do to longevity, and it might be a little loud.
 
You mention that people won't adopt EVs if they don't have the ammenities they've become accustomed to. I agree. But a 60 HP engine cannot provide the power that people have become accustomed to if this is your "prime mover" as you put it.
 
I used to live in San Diego and probably 4-6 times a year I'd make a road trip to Las Vegas with 2-3 friends. This involved about a 25 mile stretch of highway where you climb 4,000 feet in elevation where traffic is running around 75 mph. The 60 HP engine just wouldn't cut it. Granted this driving situation only took place a handful of times a year but its enough to make the vehicle less marketable. A larger battery pack could have supplemented the power on these occasions. Yeah the bulk of the time you'd be taking a mpg hit by carrying this weight around but you also take a mpg hit by carrying around the extra weight of an AC and even more of a hit when you use it. It comes down to what would be more marketable.

Messages Page 20 of 21

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