PeakOil is You
Diesel article from NY Times
30 posts
• Page 2 of 2 • 1, 2
by Bytesmiths » Tue 11 Jan 2005, 14:49:19
OOPS! That was supposed to be a PM!
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Bytesmiths - Tar Sands
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by Denny » Sun 16 Jan 2005, 17:24:03
I think the most classic everyday example of the superior torque characteristics of electric motors is the street car. A 35 ton street car is typically equipped with just a 130 hp motor unit, yet its acceleration is better than a typical bus which, though lighter, has a mot three times the output.
Electric motors can also act as generators under btraking and return the kinetic power to the grid or the battery!
Electric motors can also act as generators under btraking and return the kinetic power to the grid or the battery!
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by small_steps » Sun 16 Jan 2005, 21:58:52
$this->bbcode_second_pass_quote('starm', 's')mall_steps I don't understand what you are talking about. Bytesmiths is right electric motors have high torque at low speed. That is why you don't need the standard multi-gear transmission. The only thing you might need is some kind of clutch between the diesel engine and the generator and maybe one gear to get the right speed ration between them. Everything else can be controled by electronics.
What I was talking about was the effects of the limits of the electronics. The torque output of the machines at low speed is determined by the current ratings of the switches used (generally IGBTs). This is because torque is the product of magnetic flux and current in the machine.
The speed limit is determined by the voltage rating of the converter.
This is problematic because the voltage of a motor is proportional to speed and the magnetic flux. To go above the rated speed of the motor, we must reduce the flux in the machine.
This may be worth reading:
http://www.formulasun.org/asc/tech/SAE_1999-01-1152.pdf
Note figure 1.
You could overspec the current/voltage ratings of the converter (and motor) if you wish, but it would likely cost you in money,weight, and efficiency.
I would like to apoligize to Bytesmith, for what I had thought was a valid critism of an all-electric "transmission" and its reduced efficiency compared to the traditional transmission.
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by Bytesmiths » Sun 16 Jan 2005, 22:09:27
$this->bbcode_second_pass_quote('small_steps', 'Y')ou have added this person to your <b>Ignore List.</b> Click <u>HERE</u> to view this post.
If this guy has anything interesting and relevant to say about the topic, perhaps someone can PM me. But most likely, it's hot air and nit-picking. I feel a lot better not seeing such stuff.
Feel free to try the "Ignore" button! It sure makes a number of these discussions much more interesting and much less infuriating! :-)
:::: Jan Steinman, Communication Steward, EcoReality, a forming sustainable community. Be the change! ::::
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Bytesmiths - Tar Sands
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by fecteau » Mon 17 Jan 2005, 13:14:38
A point that has not been discussed is the higher NOx emission from a diesel engine.
I bought my Prius for it's low emission, not it's high fuel economy.
I am not sure you could achieve the same low emission from a diesel hybrid.
I bought my Prius for it's low emission, not it's high fuel economy.
I am not sure you could achieve the same low emission from a diesel hybrid.
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by Bytesmiths » Mon 17 Jan 2005, 13:54:28
$this->bbcode_second_pass_quote('fecteau', 'A') point that has not been discussed is the higher NOx emission from a diesel engine.
I bought my Prius for it's low emission, not it's high fuel economy.
I am not sure you could achieve the same low emission from a diesel hybrid.
Good point. On a per-fuel-consumed basis, NOx is slightly higher, but on a per-mile basis I believe it is actually lower or the same.
I bought my Prius for it's low emission, not it's high fuel economy.
I am not sure you could achieve the same low emission from a diesel hybrid.
Feel free to correct me -- a reference would be nice.
I know that is certainly true for biofuels in diesel engines, but I haven't done the research for plain derv petro-diesel.
Also, I've read that increased NOx emissions with biofuels can be reduced by changing the timing, at the expense of other pollutants, notably unburned hydrocarbons and particulates. Given that trade-off, we're probably better off with slightly increased NOx.
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by small_steps » Tue 18 Jan 2005, 16:19:07
$this->bbcode_second_pass_quote('fecteau', 'A') point that has not been discussed is the higher NOx emission from a diesel engine.
I bought my Prius for it's low emission, not it's high fuel economy.
I am not sure you could achieve the same low emission from a diesel hybrid.
I bought my Prius for it's low emission, not it's high fuel economy.
I am not sure you could achieve the same low emission from a diesel hybrid.
It appears you could, the FedEx project was diesel:
http://www1.eaton.com/hybrid_vehicle/index.html
For simple NOx reduction, a catalytic converter may also be used:
http://www.catalyticaenergy.com/new_tec ... diesel.htm
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