Date:         Sat, 12 Dec 2009 14:25:58 -0800
Reply-To:     Rocket J Squirrel <camping.elliott@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Rocket J Squirrel <camping.elliott@GMAIL.COM>
Subject:      Re: About coolant
Comments: To: Jim Arnott <jrasite@EONI.COM>
In-Reply-To:  <0E64F895-A8D3-417C-AEB4-9622E48639A2@eoni.com>
Content-Type: text/plain; charset=UTF-8; format=flowed

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
>