Date:         Thu, 15 May 2008 14:47:51 -0700
Reply-To:     Mike Elliott <camping.elliott@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mike Elliott <camping.elliott@GMAIL.COM>
Subject:      Re: [NVC] Beer bottle solar heater
Comments: To: Tom Buese <tombuese@comcast.net>
In-Reply-To:  <F686820A-3AB4-45D1-8E99-CE6CDDA38F5F@comcast.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 5/15/2008 2:01 PM Tom Buese wrote:

> On May 15, 2008, at 2:46 PM, Mike Elliott wrote:
>
>> Pfft. Two problems with the Coleman unit.
>>
>> 1. We're trying to maximize solar energy gathering area per unit volume
>> of water. The 5-gallon Coleman bag is about 12'' x 18'' square as I
>> recall, which provides about 1400cm^2 of surface for 19000ml of water,
>> giving us .07^2cm/ml of exposure. Assuming that we build our beer bottle
>> heater using 650ml "Bomber" bottles, and assuming an o.d. of 8cm (I
>> don't have one handy) and i.d. of 7cm, the height (excluding the neck)
>> would be around 17cm (including bottom and shoulders). This bottle would
>> cast a shadow of 136 square cm, which comes to 136cm^2/650ml =
>> .210cm^2/ml of water, or about 3 times the energy-gathering capability
>> of a stupid bag of water, and
>>
>> 2. You can't get a Coleman black plastic 5 gallon bag by drinking a lot
>> of beers.
>>
>> Sheesh.
>
> Mr. Squirrel took the words right outta my mouth.

That may be. I'm still waiting for someone to check my calculations in
#1, above. I know I dropped a decimal point or something. But even so, I
stand by the assumptions and results of #2 -- I defy anyone to prove me
wrong.

--

Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR