Diesel-electric cars...

[TheSilentChamber]

Its not the effiecency of the electric motor in question, its the converting from mechanical to electrical that is efficient.

[curtis73]

Originally Posted by KiwiBacon

Your conversion efficiencies are way out. There's no engine that can deliver 87% effciency..

Sorry, I should have clarified. I meant thermal efficiency, as in the number of BTUs stored in the fuel versus how much the engine releases during combustion.

[KiwiBacon]

Originally Posted by TheSilentChamber

Its not the effiecency of the electric motor in question, its the converting from mechanical to electrical that is efficient.

Generating power isn't that bad.
Your 12v alternator will do maybe 60% efficiency, large generators running at constant speed will beat 90% efficiency.

[KiwiBacon]

Originally Posted by curtis73

Sorry, I should have clarified. I meant thermal efficiency, as in the number of BTUs stored in the fuel versus how much the engine releases during combustion.

So you're talking about the last 13 odd % being released outside the combustion chamber?

[Steel]

*edit* er, wait. i need to look stuff up.

[dtebh]

Interesting thread...and a few notes:

I remember in the days of the VW diesel rabbit, popular mechanics had an article about a diesel electric version, with a regenerative braking system/flywheel arrangement, and they were speculating about 150+ mpg efficiency. Of course, at the time, the cost of fuel was .60/gal, and they also speculated that it would be difficult to get interest at such low fuel prices.

Now, the world turns and it deserves a new look.

I also have been tracking some very interesting rotary diesel engine technology, and the web site claims that conventional IC engines only achieve volumetric effiency in the 8-9% range, while this engine claims 30%.

The web site is www.regtech.com

Lastly, Dodge was planning a US introduction of the 2007 Caliber with a diesel engine option (reportedly was to be sourced by VW) coupled with a CV transmission (CVT), which was purported to be more efficient and simplier than current options (ie snowmobile). The new diesel engine emissions rules (specifically NOX) prevented the 2007 release, but purportedly next year. Although I am NOT a mechanical engineer, the articles on the CVT had been very positive on the higher effiency of the CVT than conventional transmissions due to less losses through no gears being meshed, no torque converters, etc. A simple test is the heat generated by transmissions, thus indicating friction loss. CVT also has the potential of keeping the engine at the most optimum operating levels/rpms since it has potentially infinite gear ratios.

So, wouldn't a rotary diesel electric engine coupled with CVT be a killer combination?

Ed.

[curtis73]

Originally Posted by KiwiBacon

So you're talking about the last 13 odd % being released outside the combustion chamber?

No, I'm talking about the 13% that isn't released at all. Unburned HCs are one way, and it also makes other compounds out of the fuel besides simply combusting it.

And, yes, there is a certain percentage that is released outside the chamber. How about the continually burning HCs in the exhaust and the catalyst?

[KiwiBacon]

Originally Posted by dtebh

I also have been tracking some very interesting rotary diesel engine technology, and the web site claims that conventional IC engines only achieve volumetric effiency in the 8-9% range, while this engine claims 30%.

The web site is www.regtech.com

Lastly, Dodge was planning a US introduction of the 2007 Caliber with a diesel engine option (reportedly was to be sourced by VW) coupled with a CV transmission (CVT), which was purported to be more efficient and simplier than current options (ie snowmobile). The new diesel engine emissions rules (specifically NOX) prevented the 2007 release, but purportedly next year. Although I am NOT a mechanical engineer, the articles on the CVT had been very positive on the higher effiency of the CVT than conventional transmissions due to less losses through no gears being meshed, no torque converters, etc. A simple test is the heat generated by transmissions, thus indicating friction loss. CVT also has the potential of keeping the engine at the most optimum operating levels/rpms since it has potentially infinite gear ratios.

So, wouldn't a rotary diesel electric engine coupled with CVT be a killer combination?

Ed.

I've just checked out that rotary site. The claims they make are very vague. Comparing power/weight to a wankel engine (wankels are terribly inefficient) and making fuel efficiency claims with no figures at all to back them up.
If they had impressive figures on BSFC (brake specific fuel consumption, what weight of fuel it takes to produce 1 kw for one hour) then they'd be shouting about it on their website.
A very good modern piston diesel engine has a BSFC 200g of diesel per kilowatt hour. The 20 year old engine in my truck can manage 220 g/kwh.

The combustion chambers are pie shaped, making for cold corners and a bad surface/volume ratio. This makes it hard to get a clean burn, hurting fuel efficiency and emissions performance.
Each vane has two sliding ends. That's a large and convoluted sealing surface.

We're at a stage with the piston engines where they're highly refined, there are many "alternative" designs out there with fantasic claims but I have yet to see one that is even competitive.

There's a New Zealand inventor currently trialling a different form piston engine. It's using a sinusoid plate instead of a crankshaft. The idea isn't better efficiency, just better packaging for certain applications.

[dtebh]

Thanks for the reply.

Granted, the reg tech stuff is only in development, but looks interesting nonetheless.