T-Pain Is On A Boat: Re: [Electric Boats] Re: 12V Accessories (Refrigeration)

Wednesday, October 24, 2012

Re: [Electric Boats] Re: 12V Accessories (Refrigeration)

John,
I considered that but the peltier module is typically 11/2"square and less than 3/16" thick. It must be compressed onto an aluminum style heat sink on the interior side (cold) and with small fan to distribute within the cooler. The hot side then is so close to the frame of the cooler container that dripping cold water on it is location wise difficult. I did consider, for faster cool down when initially going on a trip, to place ice in a container and let it drip onto the outside heat sink with fan. But then what do you do with the lime/scale buildup and don't like the idea to drip water onto electrical components. On the other hand a water cooled heat sink gives the option to pipe the fluid to a cooler location closer to the hull. Nick

--- On Wed, 10/24/12, John Francis <surv69@gmail.com> wrote:

From: John Francis <surv69@gmail.com>
Subject: Re: [Electric Boats] Re: 12V Accessories (Refrigeration)
To: electricboats@yahoogroups.com
Date: Wednesday, October 24, 2012, 6:21 AM
As to the cooling effect of water on a heat sink . . .

Since you're in water anyway(esp if you're in fresh water), why not make a reservoir(container) of water that "drips" water over the hot side of the peltier heat sink. Sure . . . you'd have to refill the reservoir every once in a while, but hey . . . the water's all around you anyway and best of all . . . it's real simple . . . I like simple and cheap and will compromise being able to freeze things for being able to keep things cool.

John Francis
Newport 28
On Wed, Oct 24, 2012 at 7:13 AM, John Green <v_2jgree@operamail.com> wrote:
Hi, Kirk, thanks for the response......sorry but I don't understand the reference to 'tons'.

I realise that an auto compressor creates cold quickly, and that I don't need that, but surely the HP required at, say, one 20th or one 50th of the RPM is less than at the speed the compressor is driven by a car engine?

I suppose a better question I should have asked is "Can automotive AC systems work at lower RPM, and if so, what are the RPM limits if any?"

Maybe I ought to just try turning a car compressor with a ratchet wrench, but they tend to have little room around them.

I know that at idle, they produce frost on exposed pipes.

And I know that they are power hogs at the design speeds driven on a vehicle.

What I don't know is if the losses at lower outputs exceed the production rates at those same outputs, assuming reasonable heat insulation.

The solar panels I have will have no spare capacity most of the time, but if the HP requirement is low enough, the cooler/fridge application might lend itself also to pedal power - any electricity savings obviously represent increased range and/or lower battery discharge levels for propulsion.

It might be possible, too, to combine a compressor system with a Peltier system, that could be used when moored etc. and when there are watts to spare, but I am currently not sure if various charging types, (ie solar and wind and backup ICE) can be combined for simultaneous use to keep the batteries 'up'.

John
Re: 12V Accessories (Refrigeration)     Sat Oct 20, 2012 1:50 pm        (PDT)        . Posted by:   "Kirk McLoren"         kirkmcloren     you lost it with small. An automobile compressor is sized, depending on application, at 1 to 2 tons. Lots of glass in a car and metal conducts well also. Rapid draw down is important. A sealed compressor with 1/8 that capacity will keep your cream cool. Assuming 50% efficiency mechanical work to electricity and then electricity to mechanical work you are at 1/4 horse versus 1 or 2. Besides in most warm places there is reliable sun. photovoltaics to battery to dedicated inverter is smaller and more reliable.  My 2 cents.       Will Rogers quote: "Stupidity got us into this â€" why can't it get us out?"   
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