Article 30618 of alt.solar.thermal:
Path: news.misty.com!not-for-mail
From: nicksanspam@ece.villanova.edu
Newsgroups: alt.solar.thermal
Subject: Re: Heat pump - heat concentrator
Date: 7 Jun 2008 14:24:21 -0400
Organization: Villanova University
Lines: 22
Message-ID: <g2ejol$8sk@acadia.ece.villanova.edu>
References: <1212853653.911.1212843719@bayman.org>
NNTP-Posting-Host: acadia.ece.villanova.edu
X-Trace: max.inside.misty.com 1212859394 4022 153.104.44.130 (7 Jun 2008 17:23:14 GMT)
X-Complaints-To: abuse@misty.com
NNTP-Posting-Date: Sat, 7 Jun 2008 17:23:14 +0000 (UTC)
Xref: news.misty.com alt.solar.thermal:30618

David Williams <david.williams@bayman.org> wrote re:

>-> >... plastic Coca Cola bottles filled with water. 
>-> Over time, they lose water through the walls. 
>  
>How much time? They hold pressurized Coke for long periods, so they 
>can't be very porous. 

Coke in PET bottles has a 6-week shelf-life in a store, determined by loss
of CO2 pressure. Googling, I couldn't find a water vapor transmission rate
for PET bottles (in say lb/ft^2-h per "Hg of vapor pressure difference per
mil of wall thickness), nor their wall thickness. OTOH,

http://www.devicelink.com/mpb/archive/98/09/005.html

says 100 square inches of "low-density polyethylene" loses about 0.4 grams of
water per day per mil (0.001") of thickness at 40 C (104 F), with 0% RH on
one side and 35% on the other. A graph shows how this decreases linearly with
inverse (1000/T(K)) temperature...

Nick