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Alex, The only BIG problem with this fridge idea is getting one down a 24" hatch. That's a pretty small fridge. David Bartsch > Date: Tue, 10 Aug 2010 12:01:51 -0500 > From: spm2@nomad.ignorelist.com > To: personal_submersibles@psubs.org > Subject: Re: [PSUBS-MAILIST] fridge vs. Ice CALCULATIONS - psub air conditioner > > Maybe you could get one of those 12v mini fridges and put the condenser (the > hot side coils) either outside the psub somehow or have some kind of heat > exchanger to the outside water. Then you just have to put your food, beer and > ice inside it and then when you want to cool off inside the psub you can just > leave the door open. > > If you get a fridge that takes 15 amps that'll be 180 Watt > s, so you could expect it to put out maybe 600 Watts of cold air. A 5,000 > BTU windor air conditioner unit used to cool a room in a house down takes 500 > Watts and puts out 1464 Watts of cooling capacity. > > Ice requires 220,000J / kg to melt it, and 4220J to raise 1kg by one degree K > after it melts. So it takes about 42200J to raise it up to 10 deg C. In total > your 1kg of water will put out about 262,000 Joules. A Joule is 1 Watt*second so > 262,000 / 3600 = 72 Watts for an hour. > > 30 liters (kg) of ice will give you about 7,860,000J or 545 Watts of cooling for > 4 hours. A 30 kg lead acid battery will put out 125 Watts for 4 hours at 50% > DOD, which is probably about 400 Watts of cooling, but you still the space that > the mini fridge takes up. The ice takes up about a 32cm square area, and you > have to haul in a new ice every 4 hours or so. I would go with the fridge. With > the fridge when you're not in the psub you can close the door and not use as > much power, and keep your food cool too. When the door is open you can put your > food in the little freezer compartment to keep it cool. > > Alex > > > > On 09-Aug-2010 ShellyDalg@aol.com wrote: > > > > In a message dated 8/8/2010 9:04:26 P.M. Eastern Daylight Time, > > spm2@nomad.ignorelist.com writes: > > > > Is the object of the psub air conditioner to lower the temperature to > > below the > > outside water temperature? > > > > Alex > > > > > > > > Hi Alex. I believe David's goal with this device is to provide a little > > cooler air when a psub is on or near the surface. A psub submerged should > > cool > > down quickly but also heats up quickly when on the surface in an area like > > Florida. > > It's been mid to high 90's here lately. The water temp is hovering around > > 84 degrees as measured at the beach but I'm pretty sure it drops rapidly > > as the depth is increased. > > Now if we can figure out how to drop the humidity level in the air. Any > > device being designed must be simple to operate, cheap to build, and use as > > little precious battery power as possible. > > Frank D. > > -- > Mailed with XFmail on 10-Aug-2010. > God saved Noah, but Noah had to build an ark! > > > > ************************************************************************ > ************************************************************************ > ************************************************************************ > The personal submersibles mailing list complies with the US Federal > CAN-SPAM Act of 2003. Your email address appears in our database > because either you, or someone you know, requested you receive messages > from our organization. > > If you want to be removed from this mailing list simply click on the > link below or send a blank email message to: > removeme-personal_submersibles@psubs.org > > Removal of your email address from this mailing list occurs by an > automated process and should be complete within five minutes of > our server receiving your request. > > PSUBS.ORG > PO Box 53 > Weare, NH 03281 > 603-529-1100 > ************************************************************************ > ************************************************************************ > ************************************************************************ > |