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Power and a bottle of wine


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Pondering wine this morning I was wondering how much power it takes to get my bottle of wine at 20 deg C down to a nice 7 deg.

How many amps is it going to cost my battery?

Any thoughts?

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I'll ask the 2 lads who may or may not get to see their families this evening.

 

Wiring my boat and making me drill lots of holes so they can add lots of weight.

 

They are playing very much on the edge........  I do have a very big backyard and a spade.

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q(J) = m x C x dT where q = energy in Joules, m mass of stuff being "heated" in grams, C = specific heat of stuff (j/g/deg.C) and dT = change in temperature.

assume 750ml wine = 825g (sg ~1.1); glass bottle = 400g; C = 2.3 - 2.7 J/g/deg.C wine; = 0.5 - 0.9 J/g/deg. C glass

 

therefore  you need [825 x (2.3 : 2.7) x 13] + [400 x (0.5 : 0.9) x 13 = 27.3 - 33.6 kJ of energy plus losses (depends on your cooling method)

 

someone else can finish this - got a meeting to get to

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4200 joule/litre/deg for water so 4200 x 13 deg = 54 KJ/litre 

 

1 Watt = 1 J/second  so 50 watt lamp uses 50 joules of energy each second. 

 

You should be able to work out the rest ....give you something to do whilst sitting at the barrier.

 

Go...!

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OK so being a bit pedantic and nerdy here, but the formulae is correct if you do not factor in losses. Inefficiency is the hardest part to add to the equation, due to so many variables. The only way it could be factored in would be to run the cooling unit for a time to get the fridge down to temperature, then measure the energy used over a given time to see how much energy it takes to maintain the Fridge box at that temp. Then add in that to your equation as a loss.
And the efficiency of Cooling units can be wildly varying between installations with some having terrible inefficiency figures. Add into that, the type of unit creating the cooling. Compressor and is it engien driven or electric and is the electric inverter controlled etc etc.

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Indeed wheels, but the question was how much energy does it take to cool the wine.

Not keep it cool, where the losses from the fridge (or whatever) must be considered. In reality it would not surprise me to have to take twice what the formula says from the battery, even starting with a cold fridge, to allow this. Battery, chemical energy, to mechanical (compressor etc), losses in the heat transfer from the refrigeration solution to the cooling method(eutectic, thin plate, etc) and the inefficiencies in the insulation etc.

As far as I know, the very fastest way to cool something is in a liquid that's below zero. Like salt water, water anti freeze solution, etc. Liquid because it contacts the whole bottle (in this case) and has much better heat transfer than gases. That's why a salt ice slurry is better than just freshwater ice...

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Indeed wheels, but the question was how much energy does it take to cool the wine.

Not keep it cool, where the losses from the fridge (or whatever) must be considered. In reality it would not surprise me to have to take twice what the formula says from the battery, even starting with a cold fridge, to allow this. Battery, chemical energy, to mechanical (compressor etc), losses in the heat transfer from the refrigeration solution to the cooling method(eutectic, thin plate, etc) and the inefficiencies in the insulation etc.

 

Yep I understood that, but the losses will still affect the time and energy required to cool the bottle down to desired temp. At an extreme, you could say it would be like chilling the bottle in a fridge with the door open.

 

 

As far as I know, the very fastest way to cool something is in a liquid that's below zero. Like salt water, water anti freeze solution, etc. Liquid because it contacts the whole bottle (in this case) and has much better heat transfer than gases. That's why a salt ice slurry is better than just freshwater ice...

It's not how cold something is, it is about how fast or efficiently the energy (as heat) can be transferred from the warmer object to the colder and then that heat pulled away by the cold object. In other words, the cold object remains at a set cold temp and does not rise by the influence of the warmer object.

Efficiency of heat transfer is about surface area and the ability of the cold thing to couple to the warm object. A or gasses, are less dense that water. Or in other words, the molecules are further apart and it is the molecules of something that become energetic due to the heat energy. Hence gasses are not great at transferring the energy. Water is better, but if you can add something ( Such as Salt or Glycol) that will mix with water and make it denser, then more molecules effectively mean more energy can be transferred through it. Because there is now more mass, the water is now able to be lowered in temperature below 0 and yet still remain liquid.

 Fresh water can only be cooled to 0degC then it turns to ice and ice can not be made colder than 0degC. Add Salt, and the temperature can be lowered to about 2degC before freezing (that is for Seawater Salinity). However, add more salt and the temperature can be lowered even further before freezing. Also because the water is now denser, the heat energy can now be transferred through it much more efficiently.

 

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Well we all know what the answer to the question what is the meaning of life?  is.

 So it will be  a version of 42.

4.2 amps. or .42 .

 alternatively one could argue that if yer getting the energy out of solars for free its nothing .

 except for when you amortise the cost of the solars and the electric fridge in. Then the first one is   say  1 boat buck for the fridge plus the same again for solars and controller  so 2 K

 $2000.00 for the first bottle.

 Whatever, its worth it to drink non socked wine.

 Also ,using the  cost method , the more you drink the cheaper it becomes.

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Yeah but you are never going to get that Beer down to a few degree's here in the summer BP

Ahh.... I was once of the same mind but having a boat with less luxuries than a Mongolian Monk I did give it a go to find you can get5 them surprisingly cold, note the use of 'cold' and not cool.

 

What I did was rugby sox and then hang them by the vang under the boom tent so you get the breeze and cooling but without the sun working against everything. It takes 30mins odd to bring warm to bearable, another 30 to cold. The boom tend funnelling the breeze also increases the goodness.

 

So I'm in with BP on this one. It works and works very well.

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Ahh.... I was once of the same mind but having a boat with less luxuries than a Mongolian Monk I did give it a go to find you can get5 them surprisingly cold, note the use of 'cold' and not cool.

 

What I did was rugby sox and then hang them by the vang under the boom tent so you get the breeze and cooling but without the sun working against everything. It takes 30mins odd to bring warm to bearable, another 30 to cold. The boom tend funnelling the breeze also increases the goodness.

 

So I'm in with BP on this one. It works and works very well.

If it took an hour, I'm guessing you had more socks hanging up than were used in the last world cup!

 

Would have been quite a sight - "look at those nice young men over there doing their laundry"!

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Yeah but you are never going to get that Beer down to a few degree's here in the summer BP

If you want to do some serious cooling down in BP's sock you can pour whiskey over it - the latent heat (cooling) is much better...  hmmm - wait a minute something doesn't seem right with this idea ...

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