On Sun, 23 Apr 2017 21:37:06 +0100, Vir Campestris wrote:
Mother nature has beaten us to this 'trick' as can be seen in the
anatomy of penguins' feet where the veins and arteries in their legs run
side by side so as to allow the veins to recover heat from the arteries
before it gets lost by contact with the ice upon which they roost or
walk. The feet themselves are little more than bones, ligaments and
tendons acting as remote controlled low temperature tolerant appendages.
In the case of the flash boiler, the hot combustion products are routed
in a contra-flow to the direction of the feed water flow from the
condenser and the boiler unit itself is extremely well insulated to
minimise unproductive heat loss through the casing.
Getting back to the original question, most electric vehicle designs
eliminate the mechanical variable ratio gearbox, electing instead to use
high power handling switching converters to control the motor speed
instead. Even when a design uses a fixed gear ratio box to better match
the loading on the drive motor, electronic drive voltage control is still
the method by which modern electric road vehicles are speed regulated.
In an ideal setup, you would have hub motors in each wheel which could
be arranged as a series wired pair on each axle to provide a built in
differential and halving of the current required to drive each axle's
worth of hub motors.
However, in order to maximise efficiency and power to weight performance
of electric traction motors, you get the best performance using a high rpm
motor which basically precludes direct drive hub motor designs unless
you're prepared to sacrifice top end performance for improved battery
economy at more modest urban traffic speeds (you replace mechanical
transmission losses with much lower electric cabling losses).
 High rpm on account it uses less turns of heavier gauge copper in its
windings, meaning reduced I squared R losses.
But needs more current to achieve the same magnetic moment.
No, what counts is magnetic reversals per second, times the iron mass.
You can achieve that with a lot of poles, or a lot of RPM.
Copper losses turn out to be pretty much independent of the
configuration, and are a more a function of as you say RPM BUT its not
'RPM' that matters, its 'poles per second'.
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
What? Are you really trying to suggest the temperature of combustion is
independent of incoming air temperature?
There are even recuperative furnaces for smelting. I suggest you look up
'recovery boiler design' before showing any more ignorance.
On Thu, 20 Apr 2017 00:18:50 -0700 (PDT), harry
Hmm, I've owned an electric car for over 30 years and I'd say that
whilst it has it's merits, it still has too many limitations to be the
primary vehicle for many (even excluding the annual holiday etc).
One of it's merits is it's simplicity (not sure it would be the case
these days?). When I first got it home (on a trailer behind my IC car)
I thought I'd give it a good check over. I checked the brakes, the
lights and the battery electrolyte levels ... and that was about it.
Ok, I know most production PEV's can go faster than 30 mph and a range
greater than 20 miles but the concept / limitations are still similar.
Now, as it happened I worked only 1/4 mile from the house so one (20p)
charge would get me to work and back (and at lunchtime) for a couple
of weeks at least (assuming I didn't go anywhere else).
It was also exempt the MOT (at the time) and carried Zero Road Tax
(but you still had to have a Tax disk <g>), was insured at about the
same cost as the original BL Mini and obviously ignoring the initial
cost / deterioration of the batteries, had hardly any other running
Not sure how many PEVs can tow a trailer or take roof bars?
Cheers, T i m
It depends. Many do not have them and use motors driven a bit like those in
CD players with constant torque no matter ewhat speed, while others use gear
trains but motors running quite fast.
Of course hybrids are far more complicated.
The problem with quiet cars though is that crossing the road in poor
visibilityccan be very dangerous.
This newsgroup posting comes to you directly from...
We looked at the Tesla and were told it didn't have a gear box.
We decided against all electric, we don't like the idea of being stuck
with a 'flat' battery on a journey. The idea of stopping for 'top ups'
on a long journey is fine until you consider the practical aspects.
Suspect someone is claiming a benefit under false pretences? Incapacity
Benefit or Personal Independence Payment when they don't need it? They
As a matter of interest, is anyone looking (as in considering making) a
hybrid electric? As in, rather than having a powerful petrol engine, a
less powerful electric motor, a normal size fuel tank and a smaller
battery (like my Toyota Auris), instead have a full-size electric
motor, larger battery, but with a small petrol engine and small fuel
That way one could stop anywhere to recharge or even do it on the go.
"It is hard to imagine a more stupid decision or more dangerous way of
making decisions than by putting those decisions in the hands of people
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