On Sat, 10 Sep 2011 04:36:58 -0500, Richard
wrote:
On 9/10/2011 1:32 AM, Bill wrote:
On 9/9/2011 11:24 PM, Richard wrote:
I've asked a few people about this personally, but I'd like to throw it
open to the larger group as well.
I'm trying to cool the boat for a few days at a time...
A normal 5000 BUT marine air conditioner can pull up to 30 amps of 12
volt power. If my house battery were new and fully charged, that's 4 or
5 hours. That won't get it for even for a weekend.
If we had a diesel engine (and ran it all day) we could use an
automotive approach. But we don't - and can't.
So, quoting Kelly Johnston (one of my favorite heroes),
"Simplicate, and add lightness".
Statement of Problem:
I want to air condition the boat for up to 3 or maybe 4 days at a time.
Independent of dock power.
With as low of a battery load as possible.
Proposed Solution:
A cooler type container with a load of dry ice and a way to move large
amounts of air across the cooler.
A sketch at:
http://www.home.earthlink.net/~cave-1/images/ac-3.jpg
I'm already thinking glycol for the fluid.
But what to make the rest of it from?
Cheap, off the shelf stuff preferred!
A pump that can handle antifreeze?
High torque low power 12 volt DC motors?
What to use for the heat exchangers?
Coils of tubing? Or auto parts?
Other than a drip pan (and a handful of brain cells),
what am I missing?
Thanks all,
Richard
have you calculated the heat capacity of dry ice? there is a reason we
employ equations first to determine feasability
Ok, show and tell!
Richard, it will take one *hell* of a lot of ice. Dry ice would be
better than water ice but I know the water numbers off hand
9 btu to melt one pound of ice, another 31 btu goin up to 60, so use
40btu per pound.
That 5000 BTU ac running 5 hours is 25000 total btu
25000/40 is 600 lbs. I won't look it up but dry ice might be 6 times
better or 100 lbs. for five hours. Do the math to get better that an
approximation but you can see you'd literally need a ton of dry ice to
do the weekend.
maybe buy ten batteries.
Karl