My son will be pleased to know that he's right.

--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
Bend, OR
KG6RCR

On 12/12/2009 12:20 PM Jim Arnott wrote:

> Short answer: yes. Water transfer heat better than glycol.
>
> Longer answer: When I worked in aerospace about a century ago, one of
> my first assignments was process control for the heat treat area. We
> solution heat treated a bunch of aluminum. (Solution heat treat:
> <http://www.azom.com/Details.asp?ArticleID=2540
>  > This was done to soften the material for forming. To reduce
> residual stress, we used a quenchant of 20% polyalkalene glycol. This
> provided a slower quench than water. Quenching in water would have
> resulted in much more residual stress and distortion. Slower quench =
> slower heat transfer.
>
> Numbers here:
> http://www.engineeringtoolbox.com/ethylene-glycol-d_146.html
> http://www.engineeringtoolbox.com/overall-heat-transfer-coefficients-d_284.html
>
>
> Water is about 14% more efficient at 220 deg F.
>
> Jim
>