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'[EE] Heating and cooling an electric car'
2007\12\10@121405 by Alex Harford

face picon face
As I was scraping the ice off my windows this morning, I was thinking
about how things would change if I were using a plug-in electric car.
When thinking about car issues, I remind myself of what a great tuner
I knew told me about testing cars: "When GM tests their cars, they
assume that you can drive from the Rocky Mountains in the winter, into
the Nevada desert in the summer, all in the matter of a few hours.
Everything in the car needs to handle that situation."

Warming the car up would be great, because an electric heater + fan
could be used to warm up the interior and defrost the windows, and it
could be on a timer (to and from work) or on remote (for shopping
trips, etc).

Another option would be a small supplemental fuel tank for a heater:
biodiesel, NG, hydrogen.  Biodiesel could be made to work even in cold
climates through a heating element.  I wasn't alive during the age of
the classic Beetle though, and I hear that the heaters in those cars
were notoriously bad.  Anyone have experience with those?

Cooling the car would be a different story.  Driving a traditional air
conditioner via electric motor would probably drain the batteries
quite a bit.  Again the cooling system could be on a timer to bring
the temperature down while still plugged in but even maintaining a
cool temperature might be difficult for an electric car.

A tank of compressed air, filled while parked, could be used to drive
a turbine for a cooling pump, and the temperature drop of the tank
itself could be harnessed as well.  An onboard air compressor would
probably be a maintenance nightmare though.

I wonder if a Peltier device would work.  I keep meaning to find some
at a surplus store so I can experiment with them.

Any other suggestions?

Alex

2007\12\10@125344 by Bob Blick

face picon face
--- Alex Harford <spam_OUTharfordTakeThisOuTspamgmail.com> wrote:

> I wonder if a Peltier device would work.  I keep
> meaning to find some
> at a surplus store so I can experiment with them.

>From my own experience I would say that Peltier
coolers are much less efficient than a
motor+compressor cooler. When doing preliminary sizing
for a Peltier cooler my rule of thumb is 5x as much
power to drive it as gets moved with equal temperature
on both sides, and 10x as much power if you've got a
typical temperature differential. And I'm not sure if
there's even any weight savings in a large scale unit
like you'd need in a car.

In most of the electric cars from the big automakers,
they used an auxiliary electric motor to run the power
steering, power brakes, and air conditioning.

Cheerful regards,

Bob

2007\12\10@132511 by Alan B. Pearce

face picon face
>I wasn't alive during the age of the classic Beetle though,
>and I hear that the heaters in those cars were notoriously
>bad.  Anyone have experience with those?

Mine was a Kombi van, '58 vintage, 6V electrics ...

I do have memories of driving through the winter dressed up 'ready to ski'
and with a rug around my legs ...

2007\12\10@134244 by David VanHorn

picon face
> Any other suggestions?

Using grid power, store up a tank of liquid nitrogen.  :)

No emissions as such, while operating, but when you're out, you're out.

2007\12\10@134510 by David VanHorn

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Didn't some of them have gasoline heaters?
Minor safety implications, and probably high emissions, but VERY
effective.  No waiting for the engine to warm up.

2007\12\10@135010 by David VanHorn

picon face
>
> I wonder if a Peltier device would work.  I keep meaning to find some
> at a surplus store so I can experiment with them.

VERY inefficient, but nuke subs use them. Then again, they have plenty
of power available, and peltiers are dead silent.

2007\12\10@140139 by M. Adam Davis

face picon face
A lot of the features we currently use are designed to be tied to a
heat generating, air sucking, always running motor.  As each new idea
came around, the primary question was "How can this be cheaply and
profitably implemented on a vehicle with this type of engine?"

I suspect we need to spend some significant time going over all the
existing luxury features we've come to depend on, as well as those in
the past that have been thrown out as too
expensive/heavy/non-profitable.

For instance, the electric car (at least in the beginning) will
hopefully be significantly lighter, with regenerative braking.
Therefore power steering and power brakes may not be necessary.  In
fact, it may be cheaper and lighter weight to move those systems to
drive by wire anyway, although many paranoids will never trust such an
arrangement we seem to be able to manage well enough in aircraft.

But then, aircraft are generally better maintained than cars (I've
seen all too many people that draw a blank when you ask them if they
change their oil!)

I think the overall car cost (including maintenance) could come down
over time as well, especially if modularity is focused on.  Rather
than replacing a single huge battery pack, for instance, have cars
developed to support 5-20 modular battery packs with their own
internal charge and discharge controllers.  Then you could keep one or
two power units in the car for general driving, reclaim storage space,
and add more if your needs/range change.  You'd only need to replace
one at a time, so you're not daunted by a $3,000 pack charge every 3-5
years, just $200 every year or so.  This would also increase pack
safety, though it would decrease efficiency by a small amount.  Each
pack could sense an impact and cut power to reduce problems with 'vent
with flames' as well as possible rescue efforts cutting live high
current power cables.

Modularity would also decrease overall vehicle cost, and be a boon to
kit vehicles.

I'm no air handling expert, but I understand that a compressor is
significantly more efficient than peltier devices.  But I suspect that
heating and cooling will need to be researched more thoroughly given
the change from gas to electric.  It would be interesting to see if
pletier coolers plating the inside of the door panels with appropriate
heatsinks and blowers on the inside of each device (individual climate
control) would be suitable.

Pay for solar cells plating the top of the car, and the warmer the car
is, the more sunlight is available, and cooling efficiency may not be
as bad a hit on battery capacity as we might otherwise think.

There are a lot of things that ought to be reconsidered in light of
this very fundamental change to the way a car is designed.

-Adam

On 12/10/07, Alex Harford <.....harfordKILLspamspam@spam@gmail.com> wrote:
{Quote hidden}

> -

2007\12\10@140141 by Marcel Duchamp

picon face
Alan B. Pearce wrote:
>> I wasn't alive during the age of the classic Beetle though,
>> and I hear that the heaters in those cars were notoriously
>> bad.  Anyone have experience with those?
>
> Mine was a Kombi van, '58 vintage, 6V electrics ...
>
> I do have memories of driving through the winter dressed up 'ready to ski'
> and with a rug around my legs ...
>

Yup, got the t-shirt, etc.

The original style (pre-1968?) ran air through a fan to cool the engine.
 If the driver wanted hot air to the cab, a lever was used to close off
the exit air duct from the engine causing the hot air to be diverted up
to the driver.  On the busses, it was such a long duct that not a lot of
hot air got up to the front. On the bugs, it worked a little better.

But both suffered from the fact that no VW air cool engine of that
vintage was ever made that did not leak oil.  So the occupants of the
vehicle got to enjoy hot stinky smoky air.

Later, a heat exchanger was added to remedy the problem a bit.

2007\12\10@140951 by Rob Robson

flavicon
face
A lot could be done by reassessing vehicle shapes and materials.

RR

2007\12\10@141405 by M. Adam Davis

face picon face
On 12/10/07, David VanHorn <microbrixspamKILLspamgmail.com> wrote:
> >
> > I wonder if a Peltier device would work.  I keep meaning to find some
> > at a surplus store so I can experiment with them.
>
> VERY inefficient, but nuke subs use them. Then again, they have plenty
> of power available, and peltiers are dead silent.

Not to mention the ready availability of an extraordinary heatsink...

-Adam

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2007\12\10@142456 by David VanHorn

picon face
> I'm no air handling expert, but I understand that a compressor is
> significantly more efficient than peltier devices.  But I suspect that
> heating and cooling will need to be researched more thoroughly given
> the change from gas to electric.  It would be interesting to see if
> pletier coolers plating the inside of the door panels with appropriate
> heatsinks and blowers on the inside of each device (individual climate
> control) would be suitable.

And the 300 degree heatsinks on the outside of the door will keep
those pesky carjackers (at least the ones without oven mitts) off.
:)

Seriously, I think you're right in that a total redesign would
probably be in order.
You can only stack on so many band-aids.

2007\12\10@162754 by Carl Denk

flavicon
face
Our first aircraft (Navion) had a gasoline heater, quite effective, but
a very few were know to cause airframe fires. The last one (Cozy
homebuilt) had a muff on the exhaust stacks. Was a little cold on long
drops in altitude when throttle might be closed for a half hour. The
favored Alaskan Turbo Navajo twin heater is exhaust muff type. Helped a
friend develop the cockpit heater.

David VanHorn wrote:
> Didn't some of them have gasoline heaters?
> Minor safety implications, and probably high emissions, but VERY
> effective.  No waiting for the engine to warm up.
>  

2007\12\10@163954 by Alex Harford

face picon face
On Dec 10, 2007 10:09 AM, David VanHorn <.....microbrixKILLspamspam.....gmail.com> wrote:
> > Any other suggestions?
>
> Using grid power, store up a tank of liquid nitrogen.  :)

That is a good idea, I have no idea how difficult it is to generate
liquid nitrogen, but if it could be done on a small scale in a
vehicle, that would be cool enough. :D

An idea I had is that the heating and cooling systems could be
modular, ie don't carry around an air-conditioning unit in the winter
when it doesn't get used.  Although a heater would probably be
necessary for year round to defrost windows.

2007\12\10@165902 by Byron Jeff

flavicon
face
On Mon, Dec 10, 2007 at 12:12:35PM -0500, Alex Harford wrote:
> As I was scraping the ice off my windows this morning, I was thinking
> about how things would change if I were using a plug-in electric car.
> When thinking about car issues, I remind myself of what a great tuner
> I knew told me about testing cars: "When GM tests their cars, they
> assume that you can drive from the Rocky Mountains in the winter, into
> the Nevada desert in the summer, all in the matter of a few hours.
> Everything in the car needs to handle that situation."

That's absolutely right. That's also the reason that most cars have huge
high horsepower engines too.

>
> Warming the car up would be great, because an electric heater + fan
> could be used to warm up the interior and defrost the windows, and it
> could be on a timer (to and from work) or on remote (for shopping
> trips, etc).

Preheating the car would be a good idea. Still need to work on heat while
running around. Any thoughts on something lightweight that has good heat
storage characteristics?

Snip...
> Cooling the car would be a different story.  Driving a traditional air
> conditioner via electric motor would probably drain the batteries
> quite a bit.

Absolutely.

>  Again the cooling system could be on a timer to bring
> the temperature down while still plugged in but even maintaining a
> cool temperature might be difficult for an electric car.

That's why most current electric cars simply ditch the AC.

> A tank of compressed air, filled while parked, could be used to drive
> a turbine for a cooling pump, and the temperature drop of the tank
> itself could be harnessed as well.  An onboard air compressor would
> probably be a maintenance nightmare though.

And heavy too which is also a problem.

>
> I wonder if a Peltier device would work.  I keep meaning to find some
> at a surplus store so I can experiment with them.

Again they suck up power. Let's think about something simpler:

Carry around an insulated container filled with a combo of water and dry
ice. Run a fan through the container into the cabin. The dry ice will keep
everything colder longer because dry ice freezes at a lower temperature.

BAJ

2007\12\10@170123 by David VanHorn

picon face
On Dec 10, 2007 4:39 PM, Alex Harford <EraseMEharfordspam_OUTspamTakeThisOuTgmail.com> wrote:
> On Dec 10, 2007 10:09 AM, David VanHorn <microbrixspamspam_OUTgmail.com> wrote:
> > > Any other suggestions?
> >
> > Using grid power, store up a tank of liquid nitrogen.  :)
>
> That is a good idea, I have no idea how difficult it is to generate
> liquid nitrogen, but if it could be done on a small scale in a
> vehicle, that would be cool enough. :D

Most of the air is nitrogen, so all you're doing environmentally is
storing it up here, and releasing there.
Plus the energy cost of course, but that could be done late at night,
I guess, when the rates are low.

2007\12\10@194823 by Josh Koffman

face picon face
On Dec 10, 2007 12:12 PM, Alex Harford <@spam@harfordKILLspamspamgmail.com> wrote:
> Warming the car up would be great, because an electric heater + fan
> could be used to warm up the interior and defrost the windows, and it
> could be on a timer (to and from work) or on remote (for shopping
> trips, etc).

And not without precedent. I grew up in Winnipeg, Manitoba, Canada, a
rather cool place to be in the winter. Our cars had block heaters to
keep the engine block slightly above absolute zero and interior car
warmers to keep the inside also a bit warmer than the exterior
temperature. Of course these needed to be plugged into your garage
(and hopefully on a timer to keep them from going all night long) so
they might not be useful for mobile applications, but the technology
does work!

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
       -Douglas Adams

2007\12\11@012929 by Apptech

face
flavicon
face
> ... block heaters to keep the engine block slightly above
> absolute zero and interior car
> warmers to keep the inside also a bit warmer than the
> exterior
> temperature. Of course these needed to be plugged into
> your garage

Not quite "of course" - inductive power transfer, already
practiced in the isolating transformer that would often be
used in the above applications, at least here, can spread
its wings a little further and allow wireless power to such
things. Not that people generally do it, even though it's an
essentially trivial task.


       Russell


2007\12\11@040955 by Alan B. Pearce

face picon face
> I wonder if a Peltier device would work.  I keep
> meaning to find some
> at a surplus store so I can experiment with them.

Maybe you should keep a lookout for a device I saw on the 'Gadget Show' last
night - a USB drinks cooler (and it was being shown by the delightful Suzi
Perry).



Yeah I know, what a useless device. An ABS box (least that is what it looked
like) shaped like a miniature fridge just large enough to hold a soft drink
can, with a 'cool plate' in the bottom. Looks very much like it is a USB
powered peltier device. Might be a cheap source of Peltier devices for
experimenting ...
http://www.iwantoneofthose.com/usb-beverage-cooler/index.html but maybe not
at that price ...

2007\12\11@044230 by Mohit Mahajan (Lists)

picon face
Btw these don't really cool your drink cans and bottles (in reasonable
time, that is). All they do is keep your already cool drinks cool.

Regards,
Mohit.

Alan B. Pearce wrote:
{Quote hidden}

2007\12\11@055030 by Apptech

face
flavicon
face
> Btw these don't really cool your drink cans and bottles
> (in reasonable
> time, that is). All they do is keep your already cool
> drinks cool.

In many cases you are probably correct.
This would depend on ambient temperature, quality of
insulation, Peltier cooling Watts and, extremely
importantly, the effective C/W rating of the output
heatsink.

Imagine you were trying to remove 10 Watts of output heat.
A 1 degree C per Watt heatsink is a bit of an engineering
marvel. A 5 degrees C per Watt heatsink is much more
achievable. In the first case the heatsink would rise about
10C ambient and in the latter, about 50 C.  Peltier cooling
ability drops with temperature differential and 30C is
probably the best one could hope for. A heatsink 10C above
ambient may deliver 20C below ambient cooling in a well
designed system. A 50C above ambient warms your drink.
Bearing in mind that the electrical input PLUS the extracted
energy must be removed via the heatsink, heating on the cold
side wrt ambient is entirely possible.

So. A well designed mega-heatsink with an efficient fan may
indeed produce a good result.

But, if real cooling power per Watt is more important than
cost, dash down to Walmart (or perhaps some other (even)
more employee friendly store, and buy a Stirling based
cooler with vastly better coolth per Watt.

       http://www.yourvalu.com/product/5726750
       www.amazon.com/review/product/B000A1FCIE?showViewpoints=1
       http://www.rvnewsdaily.com/index.php?topic=RV_Supplies_And_Acce


And BTW - if James tells you that there are no Stirling
based products on the market, tell him there are some really
cool ones available [groan].




       Russell




2007\12\11@063015 by Tony Smith

picon face
{Quote hidden}

Do they actually have a Peltier or just a fan?  You need a fan anyway with a
Peltier...  

How much cooling can you get with 2.5 watts?

I vaguely recall seeing one that was dual purpose, maybe you just flip it
over depending on whether  it's for coffee or Coke.  Might have been my
imagination.  I know the heating ones were usually just a resistor or two...

Tony

2007\12\11@064626 by Chris Smolinski

flavicon
face
We used peltier coolers to keep photomultiplier tubes (PMT) happy
(ie: at a constant temperature). As others have said, they're
terribly inefficient, just useful for certain applications. Generally
when you don't have a lot of heat to move.

--

---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com

2007\12\11@065234 by KPL

picon face
> I vaguely recall seeing one that was dual purpose, maybe you just flip it
> over depending on whether  it's for coffee or Coke.  Might have been my
> imagination.  I know the heating ones were usually just a resistor or two...
>

No need to flip anything, just apply reverse current.

I played a bit with one, it was quite powerful, 150W iirc.
Had an idea to use it as a water condenser in a vegetable drying
setup, it's just a hopeless waste of energy.

--
KPL

2007\12\11@092902 by Eoin Ross

flavicon
face
Personally I like to keep things 260 Deg C or more over absolute zero :) Its cold in Ohio - I had no idea it got that bad in Canada.

(Couldn't resist)

>>> KILLspamjoshybearKILLspamspamgmail.com 10 Dec 07 19:48:22 >>>
On Dec 10, 2007 12:12 PM, Alex Harford <RemoveMEharfordTakeThisOuTspamgmail.com> wrote:
> Warming the car up would be great, because an electric heater + fan
> could be used to warm up the interior and defrost the windows, and it
> could be on a timer (to and from work) or on remote (for shopping
> trips, etc).

<snip> Our cars had block heaters to keep the engine block slightly above absolute zero and interior car
warmers to keep the inside also a bit warmer than the exterior
temperature. <snip>

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
       -Douglas Adams

2007\12\11@105341 by Tony Smith

picon face
> > I vaguely recall seeing one that was dual purpose, maybe
> you just flip
> > it over depending on whether  it's for coffee or Coke.  Might have
> > been my imagination.  I know the heating ones were usually
> just a resistor or two...
> >
>
> No need to flip anything, just apply reverse current.
>
> I played a bit with one, it was quite powerful, 150W iirc.
> Had an idea to use it as a water condenser in a vegetable
> drying setup, it's just a hopeless waste of energy.


Well, that's easy then!

I've been meaning to get one to stick on the back of telescope mirror to
stop it fogging up.  Basically just a small heater, the fact that they're
nice & flat & heat evenly (I think) makes it easy to do.  Beats fiddling
about with other methods.

One of these days.

Tony


2007\12\11@112650 by Alan B. Pearce

face picon face
>I've been meaning to get one to stick on the back of telescope mirror to
>stop it fogging up.  Basically just a small heater, the fact that they're
>nice & flat & heat evenly (I think) makes it easy to do.  Beats fiddling
>about with other methods.

For heating I would just use a suitable aluminium bodied bolt down power
resistor mounted on a piece of 1/8" aluminium to spread the heat. I don't
know how much a Peltier deice costs, but this seems to me that it is likely
cheaper, and a heap easier to select a suitable resistor for the available
power supply, than convert whatever power you have to around 1.5V to feed
the Peltier.

2007\12\11@115939 by David VanHorn

picon face
> For heating I would just use a suitable aluminium bodied bolt down power
> resistor mounted on a piece of 1/8" aluminium to spread the heat. I don't
> know how much a Peltier deice costs, but this seems to me that it is likely
> cheaper, and a heap easier to select a suitable resistor for the available
> power supply, than convert whatever power you have to around 1.5V to feed
> the Peltier.

Yup, and you don't have to worry about the cold side dripping all over
the place.

Should be possible to automate the heating, just use the fact that
condensation causes diffuse reflection, so mounting an IRLED and
phototransistor looking at the mirror, such that the IRLED isn't
reflected into the phototransistor, heat for minimum detected
reflection.

Optek has a sensor that I designed years ago for an optical document
sensor, that has an IR emitter at 0 degrees, and detector at 45
degrees, which would work fine.  Most of the pairs that you'll find
are 45 / -45 which maximizes specular reflections, the wrong kind for
this.   In my case, I had to detect paper behind a plastic window. The
45/45 sensors could be tweaked into about 3/1 contrast ratio, but the
0/45 version got over 7000/1 on the first try.

2007\12\11@121548 by KPL

picon face
>
> Well, that's easy then!
>
> I've been meaning to get one to stick on the back of telescope mirror to
> stop it fogging up.  Basically just a small heater, the fact that they're
> nice & flat & heat evenly (I think) makes it easy to do.  Beats fiddling
> about with other methods.
>


That's even easier:)
I've seen a setup where peltier module was connected as a load to
integrated audio amplifier, those can easily steer both ways from gnd.
So just add some signal from thermistor to input and it will cool or
heat as needed.

--
KPL

2007\12\11@122708 by James Newton

face picon face
www.amazon.com/review/product/B000A1FCIE?showViewpoints=1

This is one of those products that I was very happy to be wrong about. It's
good that there are sterling products making their way onto the market. At
least one of the Amazon reviewers said that his has lasted 2 years under
continuous operation. If I had an RV or camper I would buy one post haste.

Having said that, I don't think it would heat or cool an electric car...

--
James.

{Original Message removed}

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