[NSRCA-discussion] Heat Sinks

[Gray E Fowler]

Anthony

My new plane is 99.5% complete-all I have to do is balance and align the 
wings-and then "re-learn" to fly. My kid just completed the massive soccer 
"qualifying" tournament-6 games, two weekends, nothing below 103F, so I am 
conditioned to start flying again. 




Gray Fowler
Senior Principal Chemical Engineer
Radomes and Specialty Apertures
Technical Staff Composites Engineering
Raytheon



Anthony Romano <anthonyr105 at hotmail.com> 
Sent by: nsrca-discussion-bounces at lists.nsrca.org
08/04/2008 09:17 AM
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Re: [NSRCA-discussion] Heat Sinks






Hi Gray,
 Glad to see you still lurking.
First, saw that technique to cool the batteries on the moon rover.
 
Anthony





To: nsrca-discussion at lists.nsrca.org
From: gfowler at raytheon.com
Date: Mon, 4 Aug 2008 08:51:48 -0500
Subject: Re: [NSRCA-discussion] Heat Sinks


Guys 

Considering that I do not fly E, this may not work, but here is a trick 
from the missile world where the electronics generate massive heat in a 
small package (no air cooling at mach 3!!)  that must be dissapated. 

Heat sinks work well but rely on intimate contact with the heat source, 
which can be the actual problem-how to get the battery heat into the sink 
with the odd shape of the battery packs and the flatness of the aluminum. 
Since you guys know the operating temperature of the dischaging batteries, 
choose a wax that melts just below your target temperature. Cast the wax 
around the battery pack (you need a container or tub-super thin aluminum). 
Then have the cooling fins-heat sink on top. When the batteries heat up 
the wax will melt. This phase change will cool the batteries-then the 
viscous liquid wax will also efficiently transfer the heat to the aluminum 
tub and the aluminum heat sink. The heat sink will cool the wax which then 
cool the batteries. 

After recharging, the batteries cool, the wax resolidifies and it is ready 
to go all over again. Wax is light weight, the aluminum tub-heatsink would 
need to be custom fabbed and very thin-and basically sealed.  Wax can be 
easily cleaned from the batteries if needed. 

Just a thought




Gray Fowler
Senior Principal Chemical Engineer
Radomes and Specialty Apertures
Technical Staff Composites Engineering
Raytheon 



"Earl Haury" <ejhaury at comcast.net> 
Sent by: nsrca-discussion-bounces at lists.nsrca.org 08/01/2008 04:15 PM 

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General pattern discussion <nsrca-discussion at lists.nsrca.org>



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Re: [NSRCA-discussion] Heat Sinks








Bob 
  
My thought is that packs setting on something thermally conductive rather 
than insulating seems better. Love your CO2 cartridge idea - wonder if AMA 
would consider that a "gaseous boost". 
  
Earl 
----- Original Message ----- 
From: Bob Richards 
To: General pattern discussion 
Sent: Friday, August 01, 2008 3:47 PM 
Subject: Re: [NSRCA-discussion] Heat Sinks 
I've been thinking about this, and I think the best way would be sandwich 
thin pieces of aluminum between the cells and extend past the edge of the 
pack. But I'm not sure I like the idea of placing anything electrically 
conductive between the cells. Best to provide an air space between the 
cells and duct the cooling air between them. 
 
Of course, if you really want some wow-factor in the setup, you would have 
a thermostatically controlled cowl flap that only opens up once the pack 
starts to go beyond the optimum temperature. Maybe even an emergency 
cooling system - a small CO2 cartridge from an air rifle might do. ;-)

Bob R

--- On Fri, 8/1/08, Jay Marshall <lightfoot at sc.rr.com> wrote: 
The idea of a real heat sink, maybe with the fins as part of the skin of 
the plane and in the airstream, and the LiPo cell edges bonded to the sink 
with thermal compound, has some merit and may require some investigation – 
if cooling is what we really want. 
  
 

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