Clive 13 Posted December 13, 2017 Share Posted December 13, 2017 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? Quote Link to post Share on other sites
Clipper 343 Posted December 13, 2017 Share Posted December 13, 2017 Not sure, but I'm sure the kingfisher can sort it.... Be out there this weekend to help you drink it (if you are still at the Barrier) Quote Link to post Share on other sites
ScottiE 174 Posted December 13, 2017 Share Posted December 13, 2017 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 Quote Link to post Share on other sites
BNG 44 Posted December 13, 2017 Share Posted December 13, 2017 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...! Quote Link to post Share on other sites
Black Panther 1,586 Posted December 13, 2017 Share Posted December 13, 2017 Stick it inside a thick woolen sock. Dip it in the ocean. Hang in the rigging. Repeat 2 or 3 times. Done. Zero amps. It's called the latent heat of evaporation. Works equally well with beer. 2 Quote Link to post Share on other sites
Clive 13 Posted December 13, 2017 Author Share Posted December 13, 2017 Great replies! Got to fill my dive tank at Fitzroy so I'll get around to to completing the formula later.. Cheers Scottie! See you soon Ken, it's lovely out here Quote Link to post Share on other sites
Island Time 1,235 Posted December 14, 2017 Share Posted December 14, 2017 Yep, agreed with what’s given. Not sure on the specific heat of wine though. For water, it’s 4.18J/g*C. Something to contemplate while you drink it I reckon Quote Link to post Share on other sites
wheels 543 Posted December 14, 2017 Share Posted December 14, 2017 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. Quote Link to post Share on other sites
Island Time 1,235 Posted December 14, 2017 Share Posted December 14, 2017 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... Quote Link to post Share on other sites
Black Panther 1,586 Posted December 14, 2017 Share Posted December 14, 2017 With a sock in the rigging the only energy expended is lifting from the waterline. 1 Quote Link to post Share on other sites
Addem 95 Posted December 14, 2017 Share Posted December 14, 2017 I’m more concerned that you think soaking your socks in beer is good idea. Or did I miss something? Quote Link to post Share on other sites
wheels 543 Posted December 14, 2017 Share Posted December 14, 2017 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. Quote Link to post Share on other sites
wheels 543 Posted December 14, 2017 Share Posted December 14, 2017 With a sock in the rigging the only energy expended is lifting from the waterline. Yeah but you are never going to get that Beer down to a few degree's here in the summer BP Quote Link to post Share on other sites
John B 106 Posted December 15, 2017 Share Posted December 15, 2017 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. Quote Link to post Share on other sites
Black Panther 1,586 Posted December 15, 2017 Share Posted December 15, 2017 Try it wheels. I was astounded at how good it was. Quote Link to post Share on other sites
Dagwood 57 Posted December 15, 2017 Share Posted December 15, 2017 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"! Quote Link to post Share on other sites
jim s 34 Posted December 15, 2017 Share Posted December 15, 2017 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 ... Quote Link to post Share on other sites
Crocket 12 Posted December 15, 2017 Share Posted December 15, 2017 Just drink red and the whole problem goes away. 1 Quote Link to post Share on other sites
armchairadmiral 411 Posted December 15, 2017 Share Posted December 15, 2017 Details, BP , details ! You are usually so good at them. How long in water and how long in rigging please. Say ,sitting in Fitzroy in 10 / 20 knot SW with sea temp at 18 / 19 ?...Thanks...... Quote Link to post Share on other sites
Kiwifish 30 Posted December 15, 2017 Share Posted December 15, 2017 This sounds like an emergency! Use the fire extinguisher Quote Link to post Share on other sites
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