Cold Plate / Thermoelectric?

[GordMay]

Originally Posted by LakeSuperior

Cans of beer dropped to a depth slightly greater than 15 ft...below the thermocline in Lake Superior one summer, were crushed enough to leak. We lost six or seven cans on that tragic incident.

A tragedy on two levels; the first being that you felt the need to submerge the beer.


The average summer temperature of Lake Superior is about 40 degrees Fahrenheit; hence (even near the surface) immersing beer in the Lake water will result in a very Well Chilled beverage, only suitable for American swill.

➥ Michigan Sea Grant Coastwatch

➥ Michigan Sea Grant Coastwatch

We North Americans like to say we could never drink warm beer, like those weirdo Europeans; but those that feign disgust at a warm beer have probably never had a real beer. While it is true that the toilet water flavoured swill that most N. Americans drink is best served cold, it is only because it tastes revolting, unless it is cold enough to numb your taste buds.

Chilling below 15.5 ̊C/60 ̊F starts to reduce taste awareness and reduces it significantly below 10 ̊C/50 ̊F.

While this may be acceptable for beers without an appreciable aroma or taste profile, beers brewed with more than basic refreshment in mind reveal their flavours more when served unchilled—either cool or at room temperature

Michael Jackson’s* Serving Temperatures:
Well Chilled (7 ̊C/45 ̊F) for "light" beers (pale lagers)
Chilled (8 ̊C/47 ̊F) for Berliner Weisse and other wheat beers
Lightly Chilled (9 ̊C/48 ̊F) for all dark lagers, altbier and German wheat beers c
Cellar Temperature (13 ̊C/55 ̊F) for regular British ale, stout and most Belgian specialities
Room Temperature (15.5 ̊C/60 ̊F) for strong dark ales (especially trappist beer) and barley wine.

* “Michael Jackson's Great Beer Guide”

➥ Michael Jackson's Beer Hunter - Beer Hunting

➥ The Beer Brewing » Features Serving » Serve Your Beer at the Right Temperature

[Jace]

Well, Wolfenzee, not to be too challenging, but if it's snowing out, obviously you don't need the ocean depths to keep stuff cold ... simply set it on deck.

As far as weighting it, 100 pounds of lead would be way too much. I was thinking more of liquids - sixpack of beer, gallon of milk, double liter bottles of coke, etc. Those are so dense that you could pack them down in a nylon bag with maybe ten or at the most, fifteen pounds of weight. You could even control the buoyancy, thus customizing the resistance of raising the load. And I wouldn't be leaving it down there for more than a few hours, most likely. I'd have a coke probably every few hours, or at least once a day. I'm not saying it's ideal, just workable. If it's cold at night, you could pull the pack up and leave it on deck till morning, then drop it back down again. I just don't know how deep you'd have to go to get what particular temperature, in what particular area.

However, LakeSuperior made a point I hadn't thought of - the pressure! Duh *slaps forehead* Well, I said I was green, forgot to mention that I was an idiot, sorry.

[LakeSuperior]

From a technical perspective...an "average" value can hide many sins. The specific summer I was referring to the surface water temperature across the open waters of Lake Superior was in the mid to upper 60's. Below the thermocline the water was still in the upper 40's. The bier we lost in the above mentioned incident was fine Canadian Labatt, best served well chilled in the summer.

[GordMay]

Originally Posted by LakeSuperior

From a technical perspective...an "average" value can hide many sins...

The links I previously provided were for Superior SURFACE Temperatures on Agust 20/09. I don’t recall ever seeing Superior surface temperatures in the upper 60's, except in “enclosed” rock-pools.
Notwithstanding, I take your point.
I too, have cooled beer (Labatt's "Crystal") in the lake; usually just below the surface, on the shady side of the boat.

[SURV69]

I presently live at 5-6 kwatts a day(summer/winter) . . . at home(not the boat).

When I bought my Coleman Pelzier cooler I never checked the wattage useage. Since the instructions said not to run it on a car battery for more than 4 hours without turning on the engine . . . and what the heck it seems to run almost nothing more than a small fan.

Given that a car battery is a "starting" battery, which is not made for or forgiving after a sustained power draw, I "assumed"(you know what they say about "assume"), that the power draw was indeed very low. Evidently I was wrong on three counts . . . the power draw, the lack of insulation and the need to manually control the operating hours in order to maintain a worthwhile temperature. I plead guilty to ignorance of all three.

To a fourth, I do not plead guilty. This being that the pelzier unit has been "reliable" for what it claims to deliver.

I have gone through a couple of small refrigerators(on the boat) through last year that have leaked their refrigerant or otherwise ceased working. There's nothing worse than carefully shopping for, buying, traveling a number of miles, placing it on the boat(after finding a suitable place), dogging it so one can still sail, placing frozen fun-stuff in it(like the icecream bars), watching it fail, watching the icecream soften(and the meat ripen), undogging and removing the unit, taking it back to the store(once on a motorcycle), signing return documents, getting another(putting it on my motorcyle) and repeating the entire process through the next return.

ADD to this the fact that I generally hate stores and hate shopping.

The pelzier unit has been a God-send, because it appears to operate consistently and keeps thing cool enough to satisfy me . . . abiet, it uses more energy(than I imagined) and needs to run more often because of the very poor insulation.

Nonetheless, I think you guys have made me realize the error of my ways and on my next boat upgrade, a more energy-efficient(and hopefully reliable) small fridge will be in order. BUT NOT ONE OF THOSE $1000 UNITS.

Now to ask an energy question.

Is 0.6 amp (per hour) draw at 120 volts(AC) EXACTLY the same as 6 amp draw at 12 volts(DC)? AND . . . coincidently are 12 volt appliances(DC) generally more energy efficient than similar 120 volt(AC) appliances?

[GordMay]

Yes - Peltier Coolers are highly reliable power hogs.

The Cooling Fan is only one component of a Peltier Coller’s power consumption. Peltier coolers consist of the Peltier element/junction (TEC) itself, and a powerful heatsink/fan combination to cool the TEC.

Peltier elements (Thermo-Electric Cooler, or TEC) have very low efficiency*, and consume more power than they transport. Actual Peltier elements may consume twice as much energy (in the form of electricity) as they transport (in the form of heat). Do not confuse the maximum amount of power a Peltier element can transport with the maximum amount of power usage of the Peltier element.

* TEC junctions are generally only around 5–10% as efficient as the ideal refrigerator (Carnot cycle), compared with 40–60% achieved by conventional compression cycle systems (reverse Rankine systems like a compressor).

Peltier Coolers allow cooling below ambient temperature, but unlike other cooling systems that allow this (vapour phase refrigeration), they are less expensive and more compact. Peltier elements are solid-state devices with no moving parts; they are extremely reliable and do not require any maintenance.

[motion30]

Originally Posted by SURV69

I presently live at 5-6 kwatts a day(summer/winter) . . . at home(not the boat).

When I bought my Coleman Pelzier cooler I never checked the wattage useage. Since the instructions said not to run it on a car battery for more than 4 hours without turning on the engine . . . and what the heck it seems to run almost nothing more than a small fan.

Given that a car battery is a "starting" battery, which is not made for or forgiving after a sustained power draw, I "assumed"(you know what they say about "assume"), that the power draw was indeed very low. Evidently I was wrong on three counts . . . the power draw, the lack of insulation and the need to manually control the operating hours in order to maintain a worthwhile temperature. I plead guilty to ignorance of all three.



To a fourth, I do not plead guilty. This being that the pelzier unit has been "reliable" for what it claims to deliver.

I have gone through a couple of small refrigerators(on the boat) through last year that have leaked their refrigerant or otherwise ceased working. There's nothing worse than carefully shopping for, buying, traveling a number of miles, placing it on the boat(after finding a suitable place), dogging it so one can still sail, placing frozen fun-stuff in it(like the icecream bars), watching it fail, watching the icecream soften(and the meat ripen), undogging and removing the unit, taking it back to the store(once on a motorcycle), signing return documents, getting another(putting it on my motorcyle) and repeating the entire process through the next return.

ADD to this the fact that I generally hate stores and hate shopping.

The pelzier unit has been a God-send, because it appears to operate consistently and keeps thing cool enough to satisfy me . . . abiet, it uses more energy(than I imagined) and needs to run more often because of the very poor insulation.

Nonetheless, I think you guys have made me realize the error of my ways and on my next boat upgrade, a more energy-efficient(and hopefully reliable) small fridge will be in order. BUT NOT ONE OF THOSE $1000 UNITS.

Now to ask an energy question.

Is 0.6 amp (per hour) draw at 120 volts(AC) EXACTLY the same as 6 amp draw at 12 volts(DC)? AND . . . coincidently are 12 volt appliances(DC) generally more energy efficient than similar 120 volt(AC) appliances?

You need to factor the loss tru the inverter, something on the order of 15% or so. I believe that is the difference between 12 v and 110v

[wolfenzee]

I am trying to make a very pleasant galley...I am not trying to see how I can inconvenience myself. One of the live aboards said "If I could have one thing from land I would have a freezer". I have space for a refrigerator/freezer and it is relatively inexpensive, I am building my galley in such a way so I can eventually replace the 110v fridge with a 12v system. I lived on this boat for 2 years with only a cooler in the cockpit which I barely every bought ice for. I am useually conected to shore power and when I am not I have enough power in my 8D to last awhile, the fridge I am looking at draws 1 amp AC, but not constantly....the loss from an inverter varies tremendously depending all sorts of variables (30%-70% load is the most effieciant and with electric motors pure sine waves are 20% more effiecient....too big an inverter wastes power, etc...)

[wolfenzee]

A neighboring live aboard used to have a 40quart Coleman 12v cooler, it used 4amp constantly, not on and off. He had two of them, wore out one and got another. Now he has a 12v compressor powered about 1.7 cf fridge with freezer (big enough for a couple of ice trays) and it uses less power overall.