[PSUBS-MAILIST] Thermoelectric air conditioning

[Alan James]

Thanks Marc,
I am looking at maintaining 24C  (75F) in the hull. As a starting point for heat dissipation experiments I 
came up with an average sea surface temperature of 17C (62.6F). Although sea temperatures can get 
up to 36 C in the Persian Gulf.
I will probably end up filling a bath with water at 24C & floating an aluminium enclosure with

the peltier cooler stuck to the bottom in it to see what temperature the cold side maintains.
Also of importance is the peltier's  ability to be used as a dehumidifier.
Alan


________________________________
 From: Marc de Piolenc <piolenc at archivale.com>
To: personal_submersibles at psubs.org 
Sent: Thursday, March 6, 2014 3:13 PM
Subject: Re: [PSUBS-MAILIST] Thermoelectric air conditioning
 

There's an active discussion of Peltier devices ongoing on the other 
personal submersibles mailing list 
(international_psubs_minisubs at yahoogroups.com). You might want to join it.

Quick points: you still need some way to dump heat outside the boat, 
otherwise you're just moving heat from one point you want to cool, to 
another that can't afford to get any hotter. And of course the Peltier 
device produces heat of its own.
Which leads to the second key point, namely that there is an optimum 
current for heat pumping, and for some reason the manufacturers 
routinely rate their modules for a voltage that gives a higher current, 
and thus poor heat pumping efficiency. You have to learn certain key 
characteristics of your unit and come up with your own rating. The unit 
I fooled with back in the States was rated at 12 volts, but worked much 
better with an 8-ohm resistor in series.

Marc de Piolenc

On 3/6/2014 9:08 AM, Alan James wrote:
> Hi Psubbers,
> Has anyone looked at thermoelectric coolers (peltier devices) for air
> conditioning / dehumidifying & heating.
> I'm hopeful someone might be able to save me a bit of research.
> http://en.wikipedia.org/wiki/Thermoelectric_cooling
> For those who aren't familiar, they are normally used to cool small
> units like computers, electrical cabinets & chili bins.
> They are about 1&1/2" square & 1/8"  thick with two wires coming off them.
> The unit I have is 60W & operates off 12-15V. When powered up, one side
> gets hot & the other cold.
> The cooling effectiveness is regulated by how well you can dissipate the
> heat from the hot side.
> In the submersible application the hull can act as the heat sink. By
> switching polarity you have a heater.
> The down side is that you use about 3 times more power for cooling than
> traditional refrigeration units,
> however an air conditioning unit is bulky, & it would be a trade off
> between the additional battery size & expense
> to run the peltier cooler as apposed to the bulk & expense of an air
> conditioning unit & it's associated through
> hull heat exchange unit .
> The heating faze is more economical.
> G.L. require air conditioning & humidity control in submersibles.
> Thanks
> Alan
>
>
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