# [EVDL] Cold weather mod to the iMiev



## EVDL List (Jul 27, 2007)

Hello All,

I posted a few messages in late Feb this year regarding cold weather 
operation of EV's here in Montreal Quebec. At the time I was thinking 
mostly of the Leaf but I recently took the plunge and purchased an iMiev.

I started reading and posting messages in the myiMiev forum for the iMiev 
and one of the discussion threads was on extending range in cold weather. 
A recent post had a very interesting mod that some one in Europe did to 
insulate the hot water heating unit under the car. The reasoning was the 
boiler was below the car and somewhat in the free airstream so it would 
natural to insulate it thus requiring less battery energy to heat 
up/maintain the water at a desired temp. 

This seemed to me like such a good idea I wondered why they did not do it 
at the factory. I'm a bit perplexed. So I would like the list's opinion. 
I'm sure some of you have installed these kinds of heaters in conversions. 
I don't know how "heat leaky" they are but in the post he says the exposed 
exterior of the heater got to 63 Deg C about 27 seconds after turning it 
on.Sound leaky to me.

So would there be a significant saving to doing this mod ?

Here is the link to the post:

http://myimiev.com/forum/viewtopic.php?f=9&t=224&start=30

it's the post dated 


Wed Aug 29, 2012 2:42 


Your insight appreciated.

BTW 

I am really lovin the EV. Sometimes on my way home, I politely wave "hi" 
at the gas station signs as I pass by, especially when it says 
$1.44/liter........

Don.....
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## EVDL List (Jul 27, 2007)

Hello Donald,

Yes this will work, if the heating system is design correctly. This is 
something like floor heat that I have in my home. I use a specially design 
heat tube made by HEAT WAY in Canada that is like a very flexible air hose, 
but has three outer wall coverings. Can be bend very sharp without 
collapsing.

You can get this type of heating hose at any heating supply company. Comes 
in 200 foot rolls with sizes of 0.250, 0.375, 0.500 inch and up. A 0.250 
hose comes in a dual pair where one side is use as a feed from the hot water 
heater unit and the other side is the return. This method of using a duel 
hose is call a counter pose flow system.

I use a 0.375 inch by 200 feet hose which is design to pass fluid at 6 
gallon a minute for a single zone. A very small brass 6 gallon per minute 
pump which is about 2 inches in diameter and 5 inches long that runs on a 
inboard inverter that supplies 120 vac 60 hz. The pump which is a TACO 
circulating pump only draws 0.54 amps with a head of 6 feet or increase 
loading.

The 6 gallons may be too fast, so I use a small brass flow valve to adjust 
the flow to about 1 gallon a minute to get about a 10 to 20 degree F 
difference of fluid temperature between the feed and return lines by reading 
temperature meters that are immersed into the feed and return lines.

HEAT WAY also has a heater hose attachment system that is normally use to 
attach to a under floor section. This is a aluminum sheet that has been 
bent into many V sections that look like this - VVVVVVVVVVVVV - the tubing 
is laid into each V's and then screw to the sub floor. Several sheets of 
that aluminum cover foam board is than push up against the V sections 
between each floor joist to build up to at least a 30 R Factor.

In install this type of heating system below a vehicle, I would have a large 
aluminum 0.080 sheet with flange for fastening. We call this size 0.80 
thousand to cover the V pan with enough round to install about 2 inches of 
aluminum cover foam sheets.

Make sure the foam sheets press against the V sheeting and the heat tubing 
is pressing against the floor pan.

For my hot water heating system, which is use for the existing hot water 
heater core in my EV, I use a 2000 watt 240 vac diesel engine heater which 
is about 2.5 inches in diameter and 18 inches long. It can also run on 120 
vac at 1000 watts. Uses about 8 amps either at 240 or 120 volt.

You can get these type of heaters at the large long haul truck suppliers. 
There is a optional pump and thermostat accessory, if you run just the 
heater off the main battery pack and the circulating pump and thermostat off 
a 120 vac 60 Hz inverter.

In my EV, I insulated a holding and fill tank made out of 3 inch diameter by 
30 inch long copper pipe that has 3 inch caps solder on both ends and two 
copper pipe stubs. One stub comes from the pump and the other stub goes to 
the heater core. The return from the heater core goes back to the heater 
and back to the inlet of the pump.

Everything including the tank, heater, all the feed and turn lines are 
double insulated with a very good foam tubing insulation that is design for 
air condition lines. These have a self sealant on the split that has a 
zipper you pull to seal it.

I install another insulator tubing over the first one. Yes, my feed and 
return lines covering a 1/2 heater hose becomes about 2.5 inch in diameter. 
For tight 90 degree turns, I use brass barb hose connections and a heat 
shrink hose clamp which gives you a smooth surface.

Roland






----- Original Message ----- 
From: <[email protected]>
To: <[email protected]>
Sent: Friday, August 31, 2012 2:05 PM
Subject: [EVDL] Cold weather mod to the iMiev


> Hello All,
>
> I posted a few messages in late Feb this year regarding cold weather
> operation of EV's here in Montreal Quebec. At the time I was thinking
> mostly of the Leaf but I recently took the plunge and purchased an iMiev.
>
> I started reading and posting messages in the myiMiev forum for the iMiev
> and one of the discussion threads was on extending range in cold weather.
> A recent post had a very interesting mod that some one in Europe did to
> insulate the hot water heating unit under the car. The reasoning was the
> boiler was below the car and somewhat in the free airstream so it would
> natural to insulate it thus requiring less battery energy to heat
> up/maintain the water at a desired temp.
>
> This seemed to me like such a good idea I wondered why they did not do it
> at the factory. I'm a bit perplexed. So I would like the list's opinion.
> I'm sure some of you have installed these kinds of heaters in conversions.
> I don't know how "heat leaky" they are but in the post he says the exposed
> exterior of the heater got to 63 Deg C about 27 seconds after turning it
> on.Sound leaky to me.
>
> So would there be a significant saving to doing this mod ?
>
> Here is the link to the post:
>
> http://myimiev.com/forum/viewtopic.php?f=9&t=224&start=30
>
> it's the post dated
>
>
> Wed Aug 29, 2012 2:42
>
>
> Your insight appreciated.
>
> BTW
>
> I am really lovin the EV. Sometimes on my way home, I politely wave "hi"
> at the gas station signs as I pass by, especially when it says
> $1.44/liter........
>
> Don.....
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> |
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## EVDL List (Jul 27, 2007)

Hi Donald & Roland,

I just put a rather long comment on the iMiev forum about this.

My take is that the most practical and efficient method is to use a PTC heater in place of the water matrix capable of being run off either the mains (when plugged in) or the battery pack when on the move. This has the best of both worlds electrically speaking, is relatively simple to fit and is much more efficient than the electrically heated water system that the iMiev uses. It is basically copying an ICEV and the only reason ICEVs use this system is because they have so much waste heat.

That said, there is no substitute for a fuel based heater in extreme climes and that is what I would use in those circumstance. So I guess the ideal would be to have a duel heater matrix which generally uses the PTC core but has the thump of the fuel heater when it gets really cold - or you are stuck in a snow-bound traffic jam for hours!

Regards, Martin.




> Roland Wiench wrote:
> 
> > Hello Donald,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Thanks for the replys.

I take it that it is indeed worth it to insulate the external water boiler 
heater on the iMiev. 

It would be nice to know how much the insulation would help in terms of 
numbers. If I do this mod I'll try to document the before and after in 
terms of exit temp of the the air. It's kind of hard to define what is the 
best way to quantify the results of a mod like this. I'll have to think 
about it.

Don.....
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## EVDL List (Jul 27, 2007)

Hello Donald,

Here is a R-Factor formula you can calculation the amount of insulation is 
needed that retains the BTU's lost depending on the temperature difference 
of the outside ambient air and the square foot area of the interior vessel 
or tank.

The formula in the standard form:

SQUARE FOOT or SF of exterior wall of the heater, tank, pump, feed and 
return lines.

R-FACTOR is the resistance to temperature in a material.

U-FACTOR is the inverse of R-factor or one divided by resistance
or 1/R.

TEMPERATURE DIFFERENCE or TD is the temperature difference between the 
outside of the vessel and the inside of the vessel.

BTUR's is the heat lost per hour between the inside surfaces to
outside surfaces.

We now assembly the formula as:

Btur's = SF x (1/R-Factor) x TD

To find the R-Factor of the insulation, we use convert
the formula to:

R-Factor = ( Btur's / (SF x TD))/1

Example of a calculation:

First find the diameter of the outside surfaces of the heater, storage tank, 
pump housing, the length of the feed and return lines.

For all round shapes, just use 2 x 3.14 x half the diameter x length in 
inches of each vessel and hose lines which will give you square inches.

Then divide the total square inches by 144 to get square foot.

Let say we have about 288 square inches of heating system surfaces, or 
288/144 = 2 square feet.

In any heating system, we like to have about a 100 F degree temperature 
difference, or a 70 degree inside temperature to a 30 below out side 
temperature of TD = 100

Using a tubing foam insulated that has a 1/2 wall is consider to be Five 
R-factor so the Btur's lost becomes:

Btur's = SF x (1/5) x TD
= 2 x 0.2 x 100
= 40

So the loss of heat in the heating system is 40 Btur's

A 1000 watt electric heater put outs 3412 Btur's per hour, so there will be 
very little heat lost in the delivery lines, but when the heat enters the 
passenger cable, there will be a lot more heat lost.

R-Factors of materials:

Single Pane Glass - one R Factor
Steel Panels - 0.5 R Factor
1/2 Foam - 5 R factor

Using the above formulas, calculated the heat lost of each type of surface 
area to find out what the total Btur's lost is at your lowest temperature.

Here in Montana at 4000 feet we have 9 months of winter and 3 months of 
spring with a average year temperature of 35 degrees. My passenger cabin 
floor is insulated with 2 inches of hard Dow Corning blue foam, the front 
and rear fire wall is insulated with 1 inch soft foam, the door panels with 
2 layers of 1/2 inch soft foam, the top above the head liner has the 10 
R-factor aluminize bubble type insulation.

I preheat the heating system with commercial power about 15 minutes before I 
leave with three heaters ranging from 2000 to 3600 watts to pre-heat the 
cabin to or over 80F. On the road, I normally only use 640 to 860 or 1000 
watt to maintain 60 to 65F.

Roland













----- Original Message ----- 
From: <[email protected]>
To: <[email protected]>
Sent: Tuesday, September 04, 2012 2:53 PM
Subject: [EVDL] Cold weather mod to the iMiev


> Thanks for the replys.
>
> I take it that it is indeed worth it to insulate the external water boiler
> heater on the iMiev.
>
> It would be nice to know how much the insulation would help in terms of
> numbers. If I do this mod I'll try to document the before and after in
> terms of exit temp of the the air. It's kind of hard to define what is the
> best way to quantify the results of a mod like this. I'll have to think
> about it.
>
> Don.....
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> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
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> 

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|
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| Multiple-address or CCed messages may be rejected.
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## EVDL List (Jul 27, 2007)

Hi Roland,

Thanks for the information and the formula.

I am guessing that the water boiler in the iMiev is about 2 sq feet of 
surface area.
if the outside temp is -15 Deg C and the interior of the water boiler is 
at boiling or 100 Deg C.

Then the TD would be 115 Deg C or about 239 Deg F

With no extra insulation installed around the water heater I assume the 
btuR loss would be 2 * 1 * 239 or about 500 btur. I don't know if this is 
correct because I don't know if there is any insulation factor for the 
water heater itself so I'm assuming there is none.

If 1000 watts is 3412 btu's then that would be about 146 watts of power 
loss ~(3412/500)*1000 to maintaining the temp difference just in the 
boiler 
being exposed to the external air at -15 deg C.

Since I can only drive the car for about 2 hours max That would be 2 
hours*150 or about 300 Watthours of heat loss.

If I were to insulate this with 1 inch of foam (R10) then I could 
basically reduce this by a factor of 10 to only 30 WH heat loss in 2 
hours.

It looks to me like the insulation on the heater itself will save only a 
very little in terms of energy because the energy loss in the boiler looks 
to be pretty low.

It seems that the heater in the car is 5KW so the extra ~270 watts I could 
save in insulation it would be about 5%

This is contrary to what the fellow who insulated his heater is claiming. 
He does not give numbers but he is claiming that with the insulation the 
heater temp is so high that he can back it off from full to half, still be 
comfortable and gain range. So I'm not sure what to make of this.

He did put up a picture with a thermometer in front of the air vent, so I 
can put the heat on max and do the same and see what the max temp of the 
air is on the exit into the cabin on my stock iMiev. I could do this now 
while it's warm and then do it again in Dec when it's cold and see if 
there is an effect.

>From your last message, It looks like the major drain on the heat will be 
the heat loss in the cabin because the surface area is much larger. I 
don't know how well the doors and the rest of the cabin are insulated in 
the iMiev. Probably not as well as your truck.

The whole point of my first message was to do a sanity check on the idea 
of insulating the heater itself to see if it made sense but from the above 
it looks like it's not really going to save much. That would explain why 
they didn't do it as the factory. I think it would be strange for 
Mitsibishi to save a very small amount on materials and labour to not 
install insulation on the heater if it would make the driver warmer, 
happier and range extended.

Could you re-check my math/assumptions ?

As Martin mentioned it does make more sense to install a resistive heater 
in the cabin rather then heating water. I guess this was a conversion so 
it was easier this way. The only benefit I can see is that if you preheat 
the car you do have some thermal mass in the heater and in the interior 
coil that you can lever as you drive away with the heat on. But this would 
not last long....


Thanks again 

Don....

<snip>


Hello Donald,

Here is a R-Factor formula you can calculation the amount of insulation is 

needed that retains the BTU's lost depending on the temperature difference 

of the outside ambient air and the square foot area of the interior vessel 

or tank.

The formula in the standard form:

SQUARE FOOT or SF of exterior wall of the heater, tank, pump, feed and 
return lines.

R-FACTOR is the resistance to temperature in a material.

U-FACTOR is the inverse of R-factor or one divided by resistance
or 1/R.

TEMPERATURE DIFFERENCE or TD is the temperature difference between the 
outside of the vessel and the inside of the vessel.

BTUR's is the heat lost per hour between the inside surfaces to
outside surfaces.

We now assembly the formula as:

Btur's = SF x (1/R-Factor) x TD

To find the R-Factor of the insulation, we use convert
the formula to:

R-Factor = ( Btur's / (SF x TD))/1

Example of a calculation:

First find the diameter of the outside surfaces of the heater, storage 
tank, 
pump housing, the length of the feed and return lines.

For all round shapes, just use 2 x 3.14 x half the diameter x length in 
inches of each vessel and hose lines which will give you square inches.

Then divide the total square inches by 144 to get square foot.

Let say we have about 288 square inches of heating system surfaces, or 
288/144 = 2 square feet.

In any heating system, we like to have about a 100 F degree temperature 
difference, or a 70 degree inside temperature to a 30 below out side 
temperature of TD = 100

Using a tubing foam insulated that has a 1/2 wall is consider to be Five 
R-factor so the Btur's lost becomes:

Btur's = SF x (1/5) x TD
= 2 x 0.2 x 100
= 40

So the loss of heat in the heating system is 40 Btur's

A 1000 watt electric heater put outs 3412 Btur's per hour, so there will 
be 
very little heat lost in the delivery lines, but when the heat enters the 
passenger cable, there will be a lot more heat lost.

R-Factors of materials:

Single Pane Glass - one R Factor
Steel Panels - 0.5 R Factor
1/2 Foam - 5 R factor

Using the above formulas, calculated the heat lost of each type of surface 

area to find out what the total Btur's lost is at your lowest temperature.

Here in Montana at 4000 feet we have 9 months of winter and 3 months of 
spring with a average year temperature of 35 degrees. My passenger cabin 
floor is insulated with 2 inches of hard Dow Corning blue foam, the front 
and rear fire wall is insulated with 1 inch soft foam, the door panels 
with 
2 layers of 1/2 inch soft foam, the top above the head liner has the 10 
R-factor aluminize bubble type insulation.

I preheat the heating system with commercial power about 15 minutes before 
I 
leave with three heaters ranging from 2000 to 3600 watts to pre-heat the 
cabin to or over 80F. On the road, I normally only use 640 to 860 or 1000 

watt to maintain 60 to 65F.

Roland

<snip>
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| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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## EVDL List (Jul 27, 2007)

Hi Donald and Roland,

I didn't pay much attention to the formulas the first time, but I wonder if
there is an important term missing for some applications. In particular, I
think these formulas are correct if there is no airflow. If the tank and
piping is in an area with stagnant air, I think those formulas are correct.
However if the tank is subject to significant airflow (say under the car),
then the heat losses may be much greater. Even a fairly small airflow can
greatly increase heat transfer.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of [email protected]
> Sent: Friday, September 07, 2012 2:14 PM
> To: [email protected]
> Subject: Re: [EVDL] Cold weather mod to the iMiev
> 
> Hi Roland,
> 
> Thanks for the information and the formula.
> 
> I am guessing that the water boiler in the iMiev is about 2 sq feet of
surface
> area.
> if the outside temp is -15 Deg C and the interior of the water boiler is
at
> boiling or 100 Deg C.
> 
> Then the TD would be 115 Deg C or about 239 Deg F
> 
> With no extra insulation installed around the water heater I assume the
btuR
> loss would be 2 * 1 * 239 or about 500 btur. I don't know if this is
correct
> because I don't know if there is any insulation factor for the water
heater
> itself so I'm assuming there is none.
> 
> If 1000 watts is 3412 btu's then that would be about 146 watts of power
loss
> ~(3412/500)*1000 to maintaining the temp difference just in the boiler
being
> exposed to the external air at -15 deg C.
> 
> Since I can only drive the car for about 2 hours max That would be 2
> hours*150 or about 300 Watthours of heat loss.
> 
> If I were to insulate this with 1 inch of foam (R10) then I could
basically
> reduce this by a factor of 10 to only 30 WH heat loss in 2 hours.
> 
> It looks to me like the insulation on the heater itself will save only a
very little
> in terms of energy because the energy loss in the boiler looks to be
pretty
> low.
> 
> It seems that the heater in the car is 5KW so the extra ~270 watts I could
save
> in insulation it would be about 5%
> 
> This is contrary to what the fellow who insulated his heater is claiming.
> He does not give numbers but he is claiming that with the insulation the
> heater temp is so high that he can back it off from full to half, still be
> comfortable and gain range. So I'm not sure what to make of this.
> 
> He did put up a picture with a thermometer in front of the air vent, so I
can
> put the heat on max and do the same and see what the max temp of the air
> is on the exit into the cabin on my stock iMiev. I could do this now while
it's
> warm and then do it again in Dec when it's cold and see if there is an
effect.
> 
> >From your last message, It looks like the major drain on the heat will
> >be
> the heat loss in the cabin because the surface area is much larger. I
don't
> know how well the doors and the rest of the cabin are insulated in the
iMiev.
> Probably not as well as your truck.
> 
> The whole point of my first message was to do a sanity check on the idea
of
> insulating the heater itself to see if it made sense but from the above it
looks
> like it's not really going to save much. That would explain why they
didn't do
> it as the factory. I think it would be strange for Mitsibishi to save a
very small
> amount on materials and labour to not install insulation on the heater if
it
> would make the driver warmer, happier and range extended.
> 
> Could you re-check my math/assumptions ?
> 
> As Martin mentioned it does make more sense to install a resistive heater
in
> the cabin rather then heating water. I guess this was a conversion so it
was
> easier this way. The only benefit I can see is that if you preheat the car
you
> do have some thermal mass in the heater and in the interior coil that you
can
> lever as you drive away with the heat on. But this would not last long....
> 
> 
> Thanks again
> 
> Don....
> 
> <snip>
> 
> 
> Hello Donald,
> 
> Here is a R-Factor formula you can calculation the amount of insulation is
> 
> needed that retains the BTU's lost depending on the temperature difference
> 
> of the outside ambient air and the square foot area of the interior vessel
> 
> or tank.
> 
> The formula in the standard form:
> 
> SQUARE FOOT or SF of exterior wall of the heater, tank, pump, feed and
> return lines.
> 
> R-FACTOR is the resistance to temperature in a material.
> 
> U-FACTOR is the inverse of R-factor or one divided by resistance
> or 1/R.
> 
> TEMPERATURE DIFFERENCE or TD is the temperature difference between
> the outside of the vessel and the inside of the vessel.
> 
> BTUR's is the heat lost per hour between the inside surfaces to
> outside surfaces.
> 
> We now assembly the formula as:
> 
> Btur's = SF x (1/R-Factor) x TD
> 
> To find the R-Factor of the insulation, we use convert
> the formula to:
> 
> R-Factor = ( Btur's / (SF x TD))/1
> 
> Example of a calculation:
> 
> First find the diameter of the outside surfaces of the heater, storage
tank,
> pump housing, the length of the feed and return lines.
> 
> For all round shapes, just use 2 x 3.14 x half the diameter x length in
inches of
> each vessel and hose lines which will give you square inches.
> 
> Then divide the total square inches by 144 to get square foot.
> 
> Let say we have about 288 square inches of heating system surfaces, or
> 288/144 = 2 square feet.
> 
> In any heating system, we like to have about a 100 F degree temperature
> difference, or a 70 degree inside temperature to a 30 below out side
> temperature of TD = 100
> 
> Using a tubing foam insulated that has a 1/2 wall is consider to be Five
R-
> factor so the Btur's lost becomes:
> 
> Btur's = SF x (1/5) x TD
> = 2 x 0.2 x 100
> = 40
> 
> So the loss of heat in the heating system is 40 Btur's
> 
> A 1000 watt electric heater put outs 3412 Btur's per hour, so there will
be
> very little heat lost in the delivery lines, but when the heat enters the
> passenger cable, there will be a lot more heat lost.
> 
> R-Factors of materials:
> 
> Single Pane Glass - one R Factor
> Steel Panels - 0.5 R Factor
> 1/2 Foam - 5 R factor
> 
> Using the above formulas, calculated the heat lost of each type of surface
> 
> area to find out what the total Btur's lost is at your lowest temperature.
> 
> Here in Montana at 4000 feet we have 9 months of winter and 3 months of
> spring with a average year temperature of 35 degrees. My passenger cabin
> floor is insulated with 2 inches of hard Dow Corning blue foam, the front
and
> rear fire wall is insulated with 1 inch soft foam, the door panels with
> 2 layers of 1/2 inch soft foam, the top above the head liner has the 10 R-
> factor aluminize bubble type insulation.
> 
> I preheat the heating system with commercial power about 15 minutes
> before I leave with three heaters ranging from 2000 to 3600 watts to pre-
> heat the cabin to or over 80F. On the road, I normally only use 640 to
860 or
> 1000
> 
> watt to maintain 60 to 65F.
> 
> Roland
> 
> <snip>
> -------------- next part --------------
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----------



## EVDL List (Jul 27, 2007)

I agree that these formulas will correctly calculate the amount of energy
lost from the tank once it's insulated. However, I think the formulas may
greatly understate the heat loss from the original heat tank underneath the
car and in the airflow (before insulation). 

Because of the airflow past it, it will lose heat faster. If the electric
heater is trying to keep it at a fixed temperature (to heat the inside of
the car), the losses will be greater than these formulas would indicate.
Possibly much greater. How much greater would depend on the thermal
characteristics of the vessel and how much airflow goes past it. 

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Roland Wiench
> Sent: Friday, September 07, 2012 11:02 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Cold weather mod to the iMiev
> 
> Hello Mike,
> 
> If you have a thermometer that is warm up to 70 degrees and you put it
into
> a - 30 degree temperature (no wind) it will take a certain amount of time
> before the thermometer will read - 30 degrees.
> 
> Now let's say you place the thermometer that reads 70 degrees and you put
> it into a - 30 degree temperature with a wind. The temperature just drops
> faster, but it will not go below - 30 degrees.
> 
> The Btur's = Square Foot of Exterior surfaces x (1/R-Factor) x Temperature
> Difference (TD) still hold true.
> 
> Therefore if you want to hold the inside temperature to 70 degrees in a
> ambient temp of -30 F, the TD becomes a 100 degrees difference for the
> above calculation.
> 
> This calculation of a 100 degree difference is normally use for building
heating
> in the northern U.S.
> 
> For heating a fluid to 180 degree F for a vehicle, you need 180+30 = 210
> degree F temperature difference in the above calculation.
> 
> Insulated the thermometer that is in a -30 F with a wind, you can slow
down
> the temperature drop in the thermometer, but the thermometer will not go
> below -30 F. The temperature just drops faster with a wind.
> 
> I replace the grill on the EV with a solid fiberglass cover that is shape
to the
> lines of the hood and bumper to stop any air going on the heating system.
> Air ducts direct air to the intake blowers for the motor and controller.
> 
> Double insulated the entire heater, pumps, tanks and lines with a A/C foam
> tube insulation to about 1 inch thick which will be about 10 R-Factor or
what
> we also call 1/R = u-factor.
> 
> The Btur lost will be: Btur = SF x u x TD
> 
> Roland
> 
> 


_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
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----------



## EVDL List (Jul 27, 2007)

> On 8 Sep 2012 at 0:30, Mike Nickerson wrote:
> 
> > Because of the airflow past it, it will lose heat faster.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

Why do you think that some electronics need forced air
(ie a blower pushing fresh cold air over the heatsink)?
Same effect when driving a car through the air, it needs
more energy to keep a vessel up to temp when there is
significant air flow around it, because the fast flow
tries to bring the vessel wall to the ambient air temp.
In still air, the vessel tries to heat the surrounding
air to the vessel temp, significantly reducing delta T
as you already suggested. Convection creates a low rate
of cooling, nothing comparable to forced air from either
a good blower or freeway speed driving.

Hope this clarifies,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water Tel: +1 408 383 7626


-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of EVDL Administrator
Sent: Saturday, September 08, 2012 12:06 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Cold weather mod to the iMiev



> On 8 Sep 2012 at 0:30, Mike Nickerson wrote:
> 
> > Because of the airflow past it, it will lose heat faster.
> 
> ...


----------



## EVDL List (Jul 27, 2007)

> Cor van de Water <[email protected]> wrote:
> 
> > Why do you think that some electronics need forced air
> > (ie a blower pushing fresh cold air over the heatsink)?
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Again,

I think it's true that there is an cooling effect to the moving air =

passing the heater in the bottom of the car.

to Quantify this I approached this as the "wind chill" effect which we =

normally experience and all universally hate here in Montreal.

Here is one formula for it:

http://en.wikipedia.org/wiki/Wind_chill

twc =3D 13.12 + .6215Ta - 11.37 V^.16 + .3965TaV^.16

where is the wind chill index, based on the Celsius temperature scale, Ta =

is the air temperature in degrees Celsius (=B0C), and V is the wind speed =

at 10 meters (standard anemometer height), in kilometers per hour (km/h).

I am assuming that the "wind chill" only reduces the temp of the ambient =

air to give a new Delta Temp to maintain. =


Anyways plugging in -15 deg C and 100 KM/hour (typical highway speed) you =

get an effective temp of -32 Deg C. This I can believe and seems to make =

sense.

Reading this as purely more temp differential to maintain. So if I go back =

to the initial computation. The only thing to change would be the temp =

differential.

So instead of 115 deg of temp diff it rises to 132 deg C temp diff or (269 =

Deg F)

This only slightly increases the heat loss to 2*1*260 =3D 538 btur or only =

157 watts. It was 146 watts at a temp diff of 115.

So I would say that in this case the wind chill effect is very small on =

the net heat loss in the boiler.

When I think about the cooling example of a computer CPU you can see that =

the major cooling effect is accomplished by increasing the surface area in =

the heat exchanger. The CPU has a big heat sync on it. The fan on the =

computer just replenishes the supply of ambient air at ambient temp for =

the heat exchanger to work nicely. If there was no fan then the air in the =

box would rise in temp and the Delta Temp would decrease and there would =

be less cooling of the CPU.

I don't know if I approached this problem correctly perhaps there is =

another cooling term that I am missing from Rolands initial formula.


Roland,

So far the conclusion I am drawing is that the cabin heat loss is the =

major factor. I'll start to gather some data of my own as the temps falls =

going into the winter.

Don..... =

-------------- next part --------------
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URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20120910/2a042ace=
/attachment.html =

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| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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----------



## EVDL List (Jul 27, 2007)

I think looking at the issue as a temperature gradient makes more sense. If
the vehicle is standing still, layers of warmer air will surround the heater
and the temperature gradient diminishes. Depending on how much convection
is possible (perhaps the air is trapped in place), the gradient could become
quite small, meaning a small amount of heat loss.

As soon as you put the vehicle in motion, the gradient becomes the
difference between outside air and the heater - relatively large. So, much
larger heat loss.

I have a Leaf which also has a hot water heater. I wonder how much heat
loss it has - I haven't heard any discussions on it yet.

Peri

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of [email protected]
Sent: 10 September, 2012 8:20 AM
To: [email protected]
Subject: [EVDL] Cold weather mod to the iMiev

Hi Again,

I think it's true that there is an cooling effect to the moving air =

passing the heater in the bottom of the car.

to Quantify this I approached this as the "wind chill" effect which we =

normally experience and all universally hate here in Montreal.

Here is one formula for it:

http://en.wikipedia.org/wiki/Wind_chill

twc =3D 13.12 + .6215Ta - 11.37 V^.16 + .3965TaV^.16

where is the wind chill index, based on the Celsius temperature scale, Ta =

is the air temperature in degrees Celsius (=B0C), and V is the wind speed =

at 10 meters (standard anemometer height), in kilometers per hour (km/h).

I am assuming that the "wind chill" only reduces the temp of the ambient =

air to give a new Delta Temp to maintain. =


Anyways plugging in -15 deg C and 100 KM/hour (typical highway speed) you =

get an effective temp of -32 Deg C. This I can believe and seems to make =

sense.

Reading this as purely more temp differential to maintain. So if I go back =

to the initial computation. The only thing to change would be the temp =

differential.

So instead of 115 deg of temp diff it rises to 132 deg C temp diff or (269 =

Deg F)

This only slightly increases the heat loss to 2*1*260 =3D 538 btur or only =

157 watts. It was 146 watts at a temp diff of 115.

So I would say that in this case the wind chill effect is very small on =

the net heat loss in the boiler.

When I think about the cooling example of a computer CPU you can see that =

the major cooling effect is accomplished by increasing the surface area in =

the heat exchanger. The CPU has a big heat sync on it. The fan on the =

computer just replenishes the supply of ambient air at ambient temp for =

the heat exchanger to work nicely. If there was no fan then the air in the =

box would rise in temp and the Delta Temp would decrease and there would =

be less cooling of the CPU.

I don't know if I approached this problem correctly perhaps there is =

another cooling term that I am missing from Rolands initial formula.


Roland,

So far the conclusion I am drawing is that the cabin heat loss is the =

major factor. I'll start to gather some data of my own as the temps falls =

going into the winter.

Don..... =

-------------- next part --------------
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http://lists.sjsu.edu/mailman/private/ev/attachments/20120910/2a042ace/attac
hment.html =

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
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| Multiple-address or CCed messages may be rejected.
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_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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----------



## EVDL List (Jul 27, 2007)

Hi Ron,

Spent a while trying to pin this 'effect' down to a formula or even an empi=
rical rule of thumb... eg vehicle radiator design etc but failed. There =
is definitely a 'wind chill' effect but this is normally related only to an=
imate objects eg people and animals but specifically ones which perspire an=
d the effect is often more perceived than measurable.

However, there is an extra loss due to the removal of air around the hot ob=
ject due to the movement of that air which is almost certainly directly pro=
portional to the exposed surface area BUT your constantly moving 'Delta' is=
erroneous in that the difference in temperature between the hot object and=
the air around it can only be as much as their relative temperatures. Ie,=
the 'wind chilling' effect can't take the objects temperature lower than t=
he ambient air temperature (forgive me if I have mis-interpreted you).

As the surface area is rather small - much smaller than a car radiator woul=
d be with all that honeycomb - I would agree that the losses would be fairl=
y insignificant. I would also question the assumption that the water is he=
ated as high as has been suggested. Normally the water temp in these heate=
rs is pegged at around around 80C, max. otherwise you have to have expensi=
ve expansion vessels and the like.

MW




> [email protected] wrote:
> 
> > Hi Again,
> > =
> ...


----------



## EVDL List (Jul 27, 2007)

Hello Donald,

If you maintain the Btur's input exactly to the same Btur's output at any =

temperature differential, the temperature of the interior area will remain =

constant.

After you calculate the Btur heat lost in the cabin, then the heating syste=
m =

should deliver the same Btur to maintain that temperature.

If the interior temperature drops during the time you have the EV off line =

it will take a longer time to rise the temperature if you design the heatin=
g =

system input Btur to =3D the output Btur.

If you want a higher recovery time, than double the Btur's that is required =

for a known temperature difference.

My home requires 2500 Btur to maintain 70 F. at -30 F or 100 TD. I use a =

100,000 Btur heating system where the recovery is only 1 minute and 40 =

seconds.

The glass is a vehicle has the most heat lost which is only one R-factor. =

The glass area in my EV is about 30 SF, so calculating just for the btur =

loss for the glass at 100 F TD becomes.

Btur's =3D 30 sg x (1/1-R)x 100 =3D 3000 Btur's

A 1000 watt heater delivers 3412 Btur's which will maintain the heat lost =

just for the glass.

I double that to 2000 watts for the water heat and install two cabin heater=
s =

at 640 watts on the driver side and 860 watts on the passenger side. After =

I preheat with the 2000 watt heater, I found I only need the 640 watt on =

after 2-3 miles of driving below 0 F just to defrost the windshield.

Roland


----- Original Message ----- =

From: <[email protected]>
To: <[email protected]>
Sent: Monday, September 10, 2012 9:19 AM
Subject: [EVDL] Cold weather mod to the iMiev


Hi Again,

I think it's true that there is an cooling effect to the moving air
passing the heater in the bottom of the car.

to Quantify this I approached this as the "wind chill" effect which we
normally experience and all universally hate here in Montreal.

Here is one formula for it:

http://en.wikipedia.org/wiki/Wind_chill

twc =3D 13.12 + .6215Ta - 11.37 V^.16 + .3965TaV^.16

where is the wind chill index, based on the Celsius temperature scale, Ta
is the air temperature in degrees Celsius (=B0C), and V is the wind speed
at 10 meters (standard anemometer height), in kilometers per hour (km/h).

I am assuming that the "wind chill" only reduces the temp of the ambient
air to give a new Delta Temp to maintain.

Anyways plugging in -15 deg C and 100 KM/hour (typical highway speed) you
get an effective temp of -32 Deg C. This I can believe and seems to make
sense.

Reading this as purely more temp differential to maintain. So if I go back
to the initial computation. The only thing to change would be the temp
differential.

So instead of 115 deg of temp diff it rises to 132 deg C temp diff or (269
Deg F)

This only slightly increases the heat loss to 2*1*260 =3D 538 btur or only
157 watts. It was 146 watts at a temp diff of 115.

So I would say that in this case the wind chill effect is very small on
the net heat loss in the boiler.

When I think about the cooling example of a computer CPU you can see that
the major cooling effect is accomplished by increasing the surface area in
the heat exchanger. The CPU has a big heat sync on it. The fan on the
computer just replenishes the supply of ambient air at ambient temp for
the heat exchanger to work nicely. If there was no fan then the air in the
box would rise in temp and the Delta Temp would decrease and there would
be less cooling of the CPU.

I don't know if I approached this problem correctly perhaps there is
another cooling term that I am missing from Rolands initial formula.


Roland,

So far the conclusion I am drawing is that the cabin heat loss is the
major factor. I'll start to gather some data of my own as the temps falls
going into the winter.

Don.....
-------------- next part --------------
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chment.html
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| Please take those discussions elsewhere. Thanks.
|
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| Multiple-address or CCed messages may be rejected.
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----------



## EVDL List (Jul 27, 2007)

> [email protected] wrote:
> 
> > I think it's true that there is an cooling effect to the moving air
> > passing the heater in the bottom of the car.
> ...


----------



## EVDL List (Jul 27, 2007)

> On 10 Sep 2012 at 17:47, Roger Stockton wrote:
> 
> > For example, 200LFM air flow will roughly double the heat loss. 200LFM
> > (linear feet/minute) is about 4km/h.
> ...


----------



## EVDL List (Jul 27, 2007)

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## EVDL List (Jul 27, 2007)

Hi David,

I actually graduated in Physics, but they didn't go over that much in
classes. However, I work with consumer electronics (LaserJet printers) that
generate a lot of heat, both from the fuser and the high-performance
electronics embedded in the controller.

Because of cost constraints, we try to go with passive cooling wherever
possible, and only go with forced air cooling when we have to. I have
learned that it doesn't take that much forced air movement to create
significantly more cooling than is possible with passive cooling.
Unfortunately, it can be very difficult to calculate ahead of time exactly
how much cooling you get for a certain airflow.

Mike

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of EVDL Administrator
> Sent: Monday, September 10, 2012 12:27 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Cold weather mod to the iMiev
> 


> > On 10 Sep 2012 at 17:47, Roger Stockton wrote:
> >
> > > For example, 200LFM air flow will roughly double the heat loss. 200LFM
> > > (linear feet/minute) is about 4km/h.
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Cold weather mod to the imiev*

Hello Again,

Thanks for the links Roger.

What I could take away from this link <
http://www.crydom.com/en/Tech/HS_WP_FA.pdf>

is the data in table 3.

This curve looks like it approachs 0.2 with increasing speed. It does 
confirm something that I remember hearing some time ago. In cooling 
electronics you only need a small flow to greatly improve cooling.

So If I assume a .2 correction factor for high speeds 2000-3000 LFM 
(65-90) KPM Then this is another 5 times the heat loss. or about 150*5=750 
watts.

Which is about 15% of a 5KW heater.

In the end this would not wind up saving loads of range. If I saved 
2hours*750Watts = 1.5 KW that would be about 10 Km of range. 

When you think of this in terms of the degraded winter range of about 50 
KM (with heat) it's about 20% so for me I think it's really worth it to do 
the mod.

I did have a look at the iMiev heating system this weekend and it has 
about 6 feet of hose in the loop and a small reservoir right in the front 
of the car under the hood. It looked like a lot of heat would be lost in 
all that plumbing. I'm going to go ahead and insulate the whole shabang. I 
guess I'll never really be able to do a before and after test so I'll just 
have to enjoy doing the work and have some fun and hopefully be nice and 
warm in the winter.

Thanks everyone for the suggestions and input.

Don......




<snip>

> I think it's true that there is an cooling effect to the moving air
> passing the heater in the bottom of the car.
> 
> to Quantify this I approached this as the "wind chill" effect which we
> normally experience and all universally hate here in Montreal.

> So I would say that in this case the wind chill effect is very small on
> the net heat loss in the boiler.

Wind chill is indeed a similar effect, but the formulae used to describe 
it may not apply directly to inanimate objects since 'wind chill' is most 
often used to describe the effect of wind speed on living beings (usually 
people).

This paper is a bit theoretical, but section 2.3 provides some useful heat 
loss formulae related to the behaviour of a flat plate (which the outside 
of your water tank closely approximates) in forced air flow:

<https://kb.osu.edu/dspace/bitstream/handle/1811/36947/?sequence=1>

This one might be a bit more straightforward:

<http://www.crydom.com/en/Tech/HS_WP_FA.pdf>

It provides a typical performance value of 0.5C/W for a 2ft square by 1/4" 
thick plate in still air. Further on, it provides a table giving the 
improvement associated with different values of air flow. For example, 
200LFM air flow will roughly double the heat loss.

200LFM (linear feet/minute) is about 4km/h.

> So far the conclusion I am drawing is that the cabin heat loss is the
> major factor.

I expect you are correct. However, it is almost certainly much easier to 
insulate the water tank than to significantly reduce the heat loss through 
the single-glazed windows, etc. of the cabin ;^>

Cheers,

Roger.

<snip>
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