The Electric Car
in [Design]
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From: MooseFET on 7 Aug 2007 21:25 On Aug 7, 7:42 am, Don Lancaster <d...(a)tinaja.com> wrote: > MooseFET wrote: > > > I think compressed air is a better way to go. > > Go for what? > > The energy density of compressed air is ludicrously low. > Typically one sixth of lead acid or worse. 15 wh/l is hard to acheive. It is the energy per pound not the energy per unit volume that matters. Others have seen that it is a good light way to store energy and get the power out quickly when needed. See: http://hybrid-vehicles-reviews.com/ http://www.theaircar.com/
From: MooseFET on 7 Aug 2007 21:34 On Aug 7, 8:22 am, Eeyore <rabbitsfriendsandrelati...(a)hotmail.com> wrote: > MooseFET wrote: > > JosephKK <joseph_barr...(a)sbcglobal.net> wrote: > > > Mark makol...(a)yahoo.com posted to sci.electronics.design: > > > > >> It seems to just argued against using any electric motors at all. > > > > > Yep, I think the small batteries and electric motor in the Prius > > > > are there for only 2 reasons.. > > > > > 1) efficency gained by regenerative braking > > > > 2) improve the acceleration so the ICE can be smaller also > > > > improving the efficency. > > > > > If you had the small ICE without the acceleration boost provided > > > > by > > > > the electrics, the acceleration would be poor and people would > > > > not like the "drivablility". > > > > > Intersting to note that a flywheel could provide the same > > > > advantage. > > > > > In fact I tend to think of the battery and electric motor in the > > > > Prius is just an electric implementation of a flywheel. > > > > Yes, and flywheels bring their own issues with changes yaw, pitch > > > and roll. There will have to be space for the flywheel to spin not > > > only during normal driving but the vehicle must not become a hazard > > > if it rolls over in any direction or spins out. > > > I think compressed air is a better way to go. > > Compressed air power storage is horribly lossy. Not from what I've read. The problem is the pumps. The Volvo Flygmotor busses used hydraulic pumps and motors but the energy storage was compressed air.
From: John Larkin on 7 Aug 2007 23:10 On Tue, 07 Aug 2007 12:11:15 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >On Tue, 07 Aug 2007 11:36:32 -0700, James Arthur ><dagmargoodboat(a)yahoo.com> wrote: > >>On Aug 1, 6:11 am, MooseFET <kensm...(a)rahul.net> wrote: >>> On Jul 31, 9:38 pm, JosephKK <joseph_barr...(a)sbcglobal.net> wrote: >>> >>> > MooseFET kensm...(a)rahul.net posted to sci.electronics.design: >>> >>> > > On Jul 31, 6:48 am, John Larkin >>> > > <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >>> > >> On Mon, 30 Jul 2007 23:31:20 -0700, Richard Henry >>> >>> > >> <pomer...(a)hotmail.com> wrote: >>> > >> >On Jul 30, 8:25 pm, krw <k...(a)att.bizzzz> wrote: >>> > >> >> In article >>> > >> >> <1185850948.051175.139...(a)d30g2000prg.googlegroups.com>, >>> > >> >> pomer...(a)hotmail.com says... >> >><snip> >> >>> > >> >> > OOHH!. Think of the children... >>> >>> > >> >> > You sound like a leftist weenie. >>> >>> > >> >> Not at all. Not "the" children. *HIS* children. There is a >>> > >> >> difference. >>> >>> > >> >> > Please explain again the more-efficient-at-higher-speed >>> > >> >> > feature. >>> >>> > >> >> It's entirely possible as was explained at the time. >>> >>> > >> >It was bs then and it's bs now. All fancy gearing and ignition >>> > >> >tricks will be overcome by the inevitability of the >>> > >> >non-linearity of increase of air resistance with speed. >>> >>> > >> The air resistance is highly nonlinear, cubic power:speed >>> > >> roughly, whereas other losses are essentially independent of >>> > >> speed. Every car will have an optimum speed for miles/gallon, and >>> > >> it won't be zero. >>> >>> > > It also won't be much over about 50MPH. It takes about 15 HP to >>> > > push >>> > > a modest sized car at 50MPH. The windage losses per mile run as >>> > > just about the square of the speed. >>> >>> > Not necessarily. My first new car got about 22 mpg at 55 mph and >>> > about 26 mpg at 70 mph. Back then i had plenty of documentation to >>> > back it up. Kinda funny, 70 mph occurred right the rmp torque >>> > peak. It couldn't be a coincidence could it? >>> >>> It was likely a combination of coincidence and something very wrong >>> with the car. 22MPG at 55MPH is a horrid milage. This is very like >>> the leaky fuel line case. >> >>FWIW, I've always gotten about 20% better than EPA-rated fuel economy, >>by carefully optimizing my driving. >> >>I had been driving 55 mph, then even 50 mph in an attempt to improve >>my Acura's mpg. Careful cross-country measurements show optimum fuel >>economy to be 41mpg, which applies from 85 down to 65 mph. Going >>slower reduces mpg. >> >>A gearhead pal offered a decent explanation of how providing the >>engine with optimum load and RPM by going faster makes my particular >>engine more efficient, making up for the windage loss... up to a >>point, of course. >> >>Cheers, >>James Arthur > >I'm getting 19MPG at 85MPH in my Q45 ;-) > > ...Jim Thompson I'm getting 18 MPG in my 5-cylinder Rabbit, driving to/from work on the hills of San Francisco. I average about 4000 miles per year. John
From: John Larkin on 7 Aug 2007 23:16 On Tue, 07 Aug 2007 10:34:42 -0700, Don Lancaster <don(a)tinaja.com> wrote: >Guy Macon wrote: >> Don Lancaster wrote: >> >>>MooseFET wrote: >>> >>>>I think compressed air is a better way to go. >>> >>>Go for what? >>> >>>The energy density of compressed air is ludicrously low. >>>Typically one sixth of lead acid or worse. 15 wh/l is hard to acheive. >>> >>>The efficiencies of most compressed air motors are much worse than an >>>ICE. Typically 29 percent or less. >>> >>>No means of efficiently compressing air is known. >>>Efficient compression requires isothermal operation, which can only be >>>approximated by elaborate and costly multi-staging. >>> >>>The fire service proved all this a century ago after throwing bunches of >>>engineering at the proglem. >>> >>>The ONLY thing compressed air has going for it is shop floor >>>convenience. Hydraulics immediately get substituted when serious tail >>>twisting or anything remotely approaching efficiency is needed. >> >> >> The ONLY thing? >> >> There are other advantages. With pneumatics the light-load >> cycle rate is higher, the piping for distribution doesn't >> need to have a return path, and in some clean-room applications >> the system can tolerate traces of ultrapure gas leaking into >> the working area, but not any sort of liquid. >> >> Hydraulics win for strength, efficiency, positional control, >> stiffness, and safety if a pipe or cylinder bursts. >> >> You will never see pneumatics in a bulldozer, and you will >> never see hydraulics in a machine that puts CDs into CD >> cases. Having worked as a design engineer for both Parker >> Hydraulics and SMC Pnuematics, I don't see either of them >> cutting into the other's business. >> > > >And the number of pneumatic combined CD case stuffers and automobiles >currently on the road is....? I just got my wife a Honda Fit, with electric power steering. Very cool car. It's the creamsicle orange/copper color. I'm soooo tired of seeing entire blocks of cars that are all grey and silver and black. John
From: Don Lancaster on 8 Aug 2007 00:43
MooseFET wrote: > > It is the energy per pound not the energy per unit volume that > matters. > > http://www.theaircar.com/ > Not even wrong. Energy per pound is TOTALLY MEANINGLESS for terrestrial vehicle apps. See http://www.tinaja.com/glib/energyfun.pdf for a detailed analysis and explanation. Short form: tripling the mass density of gasoline would do jackshit for tranaportation. Possibly lightening a vehicle by 26 pounds. Conversely, finding a way to contain 13 pounds of hydrogen in a 26 pound container flat out ain't gonna happen. Volume density is crucial. Mass density is useless. -- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don(a)tinaja.com Please visit my GURU's LAIR web site at http://www.tinaja.com |