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Diesel, Hybrid Cars
#387 of 395 ... Some Hands on Explanations
Feb 21, 2007 (8:22 pm)
... A thermodynamicist might say, the turbo takes heat and turns it into rotation, but let's look at what actually happens. Some of the efficiency is a reduction in pumping losses, but a big on-highway truck, at a fairly common 40 pounds of boost, is making fifty horsepower, just by turning the intake stroke into a power stroke, not even considering the increased cylinder filling. If you take the standard BMEP equation and go to the IMEP equation with, the 40 pounds pressure, with a nominal 850 cubes that is the horsepower created.
... This is a little harder to calculate, because I don't know the BSFC numbers from back then. The performance of todays vehicles is taken for granted but the level would take a non turbo engine of 1500 cubes. Back in the early Sixties turbos where almost as rare as they are ubiquitous today and most typical normally aspirated, 850 cube engines, made horsepower in the low two hundred level; today drivers expect 500 plus hp.
#388 of 395 Would love to have theopportunity to try this myself...
Mar 21, 2007 (4:07 am)
I will try and post a sane distillation of whats in my head!
I know the major thing holding back all electric vehicles per se is battery technology, we can't get enough juice for the given size/weight to make an electric car go the distance we would want out of a family car (what about 350 miles on a tank) I also know that even the latest li-poly batteries still take a while to charge...
I also know that if we all made a slight change in our driving habits and if our workplaces would provide sockets for charging your car whilst at work and our respective governments help put in place the infastructure for charging your car at home(I live in an appartment without a garage, so running an extension cord out to the car would get me loads of more headache ) we could all live with and love the current best of breed electric cars (tesla roadster is an example of the right technology, but, the wrong application for most of us)
That said I also think a better more gradual change involves, hybrid cars that still run on petrol, but, eek out the most efficiency out of the fossil fuel and as a by product lower emissions drastically. Which brings me to the meat of my post, Ive posted some of this here before, but talked about a diesel engine powering a generator that charges an onboard battery and drives an electric motor that drives the wheels (a serial hybrid). I realise that by adding the conversion from fossil fuel to electricity and storing most if it then converting it back to motive power to the wheels involves a few losses of efficiency. But really how much are we talking here?
Im going to make some assumptions here: (these are not based in fact, just my guess)
Typical motor electricity to motive power efficiency: 85-90%
Typical generator motive to electricity efficiency: 80-90%
So a simple scenario where we replace the drive train (gearbox, clutch, drive shafts) with a generator coupled directly to our gasonline engine, which then powers a motor driving the wheels, would net us a lower estimate of about 68% of the engine output (85% * 80%).
With the original clutch/gearbox in place I know you lose some of the engine power too, what is this roughly, about 10-15%? Would this electric drivetrain be any lighter than the equivalent mechanical drive train(gearbox, clutch) I know drive shafts would be needed for the electric motor too, but with in wheel motors being talked about this too might not be needed!
How much loss in efficiency in using this electric drive train are we a talking about over the mechanical drive train? My of the top of the head guess would put it about 20%.
Now couldnt this be efficiency loss be made up in using a smaller lighter gasoline engine (3 cylinder, lean burn, 1-1.5 litre capacity) that has been tuned to run at a higher rpm with turbo charging if necassary?
Wouldnt focusing on a smaller lighter more efficient gasoline engine that dont need to provide a wide power band, just a very small highly efficient band of power producing electricity to power the motor. (you could even include some ultracapicators that could soak up the excess electricity produced if the car is moving too slowly for amount of electrical power the gasoline engine/generator combo is producing and if you were to use regenarative braking, this could then be used to provide extra power to the motor when needed, or when restarting the gasoline engine if its been shutdown)
Sorry that this post is long, but, Im fascinated by all of this, should have been an engineer instead of the desk bound computer programmer that I am !!!!
Any ideas, criticism is welcome as is any kind soul that can point out any huge holes in my understanding or concept.
Its all gone very quiet on this board of late!
#389 of 395 Re: GM Expertise in Diesel Hybrid transit [toyolla2]
Mar 21, 2007 (2:38 pm)
This is a follow on from my previous post on over-powered hybrid transit buses.
"engine and a hybrid transmission consisting of two 100 kW motors and a 600-volt, nickel metal hydride battery pack. The engine is coupled to an electronically variable transmission that provides an infinite range of gear ratios to drive the wheels."
After some digging I found that Cummins engines in the 250-280Hp are the prime movers for the above. And a max service speed of 65mph was quoted.
Elsewhere someone provided these links regarding the iconic London Transport double decker bus. tfl= transport for London
The release didn't state the manufacturer of the 1.9L diesel engine that powers this vehicle. The vehicle itself was built by WrightBus Limited. No indication was given either whether this was in fact a government funded project along the lines suggested by those researchers, that government funding be awarded only for designs with a 90Kw power ceiling.
In the light of what WrightBus have achieved it's hard to see why Allison would need 210Kw for their vehicle. But if I was running GM I would be asking questions.
#390 of 395 Re: Would love to have theopportunity to try this myself... [lensman]
Mar 25, 2007 (7:55 pm)
... Lensman, check out my post # 187 in the Tesla thread.
#391 of 395 PHEV diesel !! Cool !! Go DC !!
Mar 27, 2007 (6:39 am)
Good Job DC !!! KUDOS !!!
The Dodge Sprinter PHEV has the ability to drive up to 20 miles on electric-only power. It accomplishes this with a switch on the dashboard giving the operator the ability to manually switch between modes as needed, or automatically by the vehicle control system. Two different combustion engines are being offered in the Dodge Sprinter PHEV -- diesel or asoline. The diesel version will yield the highest fuel economy benefit and is the first fleet test of a diesel plug-in hybrid system.
Mar 31, 2007 (9:14 am)
Because there is no currently available SUV with a Hybrid-Diesel I purchased a 2008 Mercury Mariner Hybrid-Atkinson. The Atkinson cycle really is quite good--it has nearly complete expansion as opposed to the Otto cycle, which does not. On the 2008 EPA ratings, the 4WD Mariner (and its sibling Escape) is supposed to get 29 mpg city, 27 mpg highway, 28 mgp combined. Mine is not, of course, broken in yet, but I got 26 mpg on the first fillup, 24.5 on the second, and currently am getting 27.7. We'll see in a few thousand miles...I'm hoping to achieve 30 mpg!
#393 of 395 Long Trip Fuel Economy
Apr 07, 2007 (9:21 am)
I recently had to drive to Southfield, Michigan from Trevose, Pennsylvania, and back--a total of over 1200 miles. In my 2008 Mercury Mariner Atkinson-Hybrid I got 31 mpg going West and 32 mpg going East, the difference probably being due to the difference in wind direction. So I easily made my goal of 30 mpg or better!
#394 of 395 A-B-O-U-T D-A-N-G T-I-M-E !!!!!!!!!!!!
Jun 13, 2007 (6:23 am)
Diesel plus hybrid equals 70+mpg
The latest diesel-powered cars offered in Europe come close to - and in a lot of cases beat - hybrid-electric cars like Toyota's Prius in the mileage stakes, so imagine what would happen if you combined the best of both technologies. France's Peugeot hopes to do just that and by becoming the first carmaker to launch a diesel-electric hybrid by the end of the decade.
The recently launched midsize Peugeot 308 hatch will be the first vehicle fitted with the new powertrain, but it's likely other models will soon follow suit if it proves to be successful.
The Peugeot diesel hybrid should average better than 70mpg (58.3mpg US), which would mean its emissions levels would be lower than most other cars except for pure electric vehicles. By comparison, the Prius rates 65.7mpg (54.7mpg US). However, most motoring mags have found its real-world fuel economy ratings to be much lower.
The only factor holding back the release of the hybrid 308 is the high cost of the batteries and electric motor, but engineers are working hard to make the technology more affordable.
#395 of 395 Another update on the Peugeot 308
Aug 29, 2007 (8:27 am)
Smoking hot diesel hybrid for sale in 2010
Now they have it testing at 80 MPG on the Euro circuit, or about 67 MPG USA.
Of course the lucky Europeans will get it first GRRRRRRRRRR !!!