Construction details and specs here.
The guy has a pretty funny account of getting his "trailer" registered at DMV here.
. . . . only in Portland (I think!)
Posted on 08/23/2003 6:06:27 PM PDT by eldoradude
I wish you well on your P.E. exam - usually in October for the fall if I remember right. That 8 hour exam makes for a long day to as I recall - as did the 8 hour EIT exam. Are you taking the mechanical discipline exam? I took it several years ago. Study hard, its a good feeling to go in prepared, zip it - coming out knowing you blew it away. Make sure you use all 8 hours.
True, except that sometimes adding intermediate steps will allow other steps to be performed more efficiently.
Most internal-combustion engines are really only efficient in a rather limitted part of the torque-RPM 'space'. If adding more energy-conversion steps to an automobile allows the engine to be used in a more efficient operating region, the increase in efficiency in the engine may more than outweigh the energy losses elsewhere in the system.
As a simple example, imagine a car with no transmission--just a clutch, and a moderately-geared differential. Such a car would not be very good, since at low speeds the engine RPM would be very low, and at high speed they'd be very high. Nonetheless, one could construct a car that way and avoid friction losses in the transmission.
Adding a transmission to such a car, however, improves its efficiency by allowing the engine to be used in a better portion of its torque-RPM range. The trnasmission itself absorbs some energy due to frictional losses, but the improvements in engine operation far outweigh the frictional losses in the transmission.
Indeed, it would seem that even without using electric energy storage it might be possible to use a hybrid design to improve efficiency by having electronics work to keep the engine operating along the most efficient torque-RPM curve; except at the slowest speeds, speed control would be accomplished by varying the transmission while the engine remained at wide open throttle. It might be difficult to make the accelerator response on such a car 'feel' right for drivers accustomed to a car whose throttle is controlled by the accelerator (it certainly wouldn't sound right) but efficiency could probably be improved greatly compared with a conventional automobile.
One big problem with internal combustion engines is that engines that can put out a lot of power are generally inefficient when putting out less, except when run at lower RPM's where their torque is rather anemic. Control electronics to operate engines on the optimal torque-RPM curve could help solve this problem.
I wouldn't be surprised if cars have a peak efficiency in that range; car engines are often used far outside their peak operating parameters, however.
Actually, I tend to think that a properly-designed electronic transmission could do a lot to improve automotive efficiency. My understanding is that engines operate by far most efficiently at wide-open-throttle; a throttle makes an engine run much less efficiently. Unfortunately, an engine which is running at pure wide open throttle has a very unstable output response: when the engine is producing surplus torque, it will speed up and produce even more surplus torque; when it is producing insufficient torque for the load, it will slow down and produce even less torque.
It would seem that suitable control electronics, however, could tame this behavior. If the electronics were to monitor the power being produced by the engine and the power demanded by the wheels to produce the desired behavior (maintaining speed, accellerating, or deccelerating at a rate insufficient to require braking), it could adjust the simulated "gear ratio" appropriately. To yield good performance it may be necessary to make gear-ratio adjustments hundreds of times per second, but with an electronic transmission that should not be a problem.
Pure, unadalterated, bullshit.
Deisel-electric conversion - 20 percent efficienct.
Electric-mechanichal conversion - maybe 80% efficient.
.8 X .2 = .16
A whole lot less efficient than any gasoline engine...
Construction details and specs here.
The guy has a pretty funny account of getting his "trailer" registered at DMV here.
. . . . only in Portland (I think!)
(my front license plate reads "EAT MORE POSSUM".) << g >>
Yes and no.
When, after 17 years, I had to replace my last bought-new car, I said what the hell. I commute in the Sacramento valley, no hills to speak of and the only other serious factor is wind.
I have had the Toyota Prius hybrid a bit over 5 months now and the improvement in efficiency is about 1/3 for my commute 37 miles each way, from 30 MPG (2-seater) to 40 MPG (5-seater).
But...
I have noticed that on a round trip to San Francisco, going over a major coastal range and a few minor ones, that the efficiency increases to about 46 MPG. Same thing happened on a trip to Lake Tahoe.
All were at normal highway speeds, albeit the "mountain" trips of necessity had much more time at reduced speeds. But, the "mountain" trips also involved long periods of climbs and downhills.
I have no explanation for it, Yet.
And yes, within town the efficiency also seems to improve, but I don't do enough of that type of driving to have a good feel for the improvement.
What exactly was it that rung your bell and inspired such creative language?
But this probably helped -
The idea is to improve the energy conversion process so it makes use of more and throws less away. Though not feasible for other reasons, electric cars have an efficiency of 90 to 95%. Meaning they use $95 and throw only $5 to $10 away. And the reason for this is the inefficiencies in the mechanical transimissions, etc. not chemical to mechanical energy conversion.
All that electricity was free, right? No conversion costs?
And you have 100 % efficient batteries?
The DoD wants to talk to you...
I try not to write thesis on this site - I don't like to read them (and ususally don't), and I wouldn't expect others to either.
The point is efficiency and system improvements. That's what an engineer does, tries to make improvements. So we analyze systems to do this. Hybrids work. Pure electric cars don't. By the way I did submit a paper to the DOE on hybrids, but not for 100% efficient batteries.
Where did diesel fuel come from?
Electricity is a supplemental power source in a hybrid, not the primary. Electical power is used to target points of inefficiency in your regular car engine.
More likely an Algore sticker.
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