The science of Freezing. Do Freez Paks work??

[Cadence]

Originally Posted by Dockhead

It does not reduce the cooling power required, and it interferes with air circulation around your food, which is the only way it gets cooled down. Don't overcomplicate a simple thing. Just put your food in the fridge (or freezer) and don't worry about it.

You need to remember that came from Mark with his wry sense of humor.

[Dockhead]

Originally Posted by warrior 90

Thermal storage is a good idear in combination with solar power.
Since cold space is limited I prefer beer,fruit juice and water for thermal storage

I agree. Thermal storage is in general a good idea -- adds hysteresis to the system and might allow you to shut down the compressor for periods of time when power is short. Same concept as a holding plate. This is a completely different concept from displacing the air in the box with peanuts, styrofoam, etc., which don't have any thermal mass and so don't perform this function.

[Cadence]

Originally Posted by warrior 90

Thermal storage is a good idear in combination with solar power.
Since cold space is limited I prefer beer,fruit juice and water for thermal storage

Fruit juice and water? I'm waiting for the squire beer cans to minimize the air in the reefer.

[Cadence]

Originally Posted by Cadence

You need to remember that came from Mark with his wry sense of humor.

Quoted the wrong thing. Mark posted the one about the foam.

[Dockhead]

Originally Posted by Cadence

Fruit juice and water? I'm waiting for the squire beer cans to minimize the air in the reefer.

I can just imagine the conversation with the Admiral:

"Darling, we simply must acquire three more cases of beer -- it's thermal mass, you know! Otherwise the vegetables will rot!

[sailorboy1]

Originally Posted by Dockhead

I can just imagine the conversation with the Admiral:

"Darling, we simply must acquire three more cases of beer -- it's thermal mass, you know! Otherwise the vegetables will rot!

Admiral - "You right, please take out the vegetables so there is room for 5 cases of beer"

Some people need better leadership on their boat

[category4jay]

Those little suckers work great BUT eventually they will break and you will be cleaning up blue glycol (I think) liquid.

[Dockhead]

Originally Posted by category4jay

Those little suckers work great BUT eventually they will break and you will be cleaning up blue glycol (I think) liquid.

Another advantage of using beer as thermal mass . . . .

If those little suckers break, you just lick it up -- done; problem solved. Hic.

[SV THIRD DAY]

But, what comes in with the air?
If only air came in...then sure...no big deal.
Just ignore it and go cruising...but my friends, the game changes when humidity comes in with the air!

The problem with Warm/moist air entering the fridge/freezer is two fold.
But the air is almost a mute point, so forget about it....it's all about the humidity!

First:
The moisture will plate out on the holding plate or thin rolled Aluminum evaporation plate. Once this frost gets over 1/4" think you start getting the Igloo affect and you dramatically decrease the efficiency of heat transfer from the Box to the holding plate/evaporator.

Second:
The humidity that comes in with the air takes BTUs to condense and phase change from a gas, to liquid, to solid...that is energy baby.

So the humidity is literally sucking up BTU energy as it condenses on your holding plate/evaporation plate AND then it kills you by making the heat transfer slower...it's a double whammy!

Air...who cares....humidity...ya...that will add to your power usage big time.

How do I know this...cruiser myth...guesses....no, from the dual test boxes running 24hrs/day at the office hooked up to a data logger and the research scientist in me that loves data and test conditions! I can measure a 30% loss in efficiency (29.7%) on identical boxes, identical test conditions with identical refrigeration systems running with the only difference being a clean holding plate/evaporation plate vs one ices up with an approximate thickness of 0.35". That's real power at the end of the day just for keeping your unit defrosted!

[MarkJ]

Ok, i have taken everything out except food. Damn thing looks empty now.

I shall report back with any significant findings.

BTW i don't have a wry sense of humour. I only drink beer, not wiskey.




Mark

[socaldmax]

That would have been a rye sense of humor.

[Cadence]

Originally Posted by MarkJ

Ok, i have taken everything out except food. Damn thing looks empty now.

I shall report back with any significant findings.

BTW i don't have a wry sense of humour. I only drink beer, not wiskey.




Mark

Yes you do. You must drink beer made out wry.

[socaldmax]

I premix my margaritas and put them back into the 1.75L containers in the freezer. Due to the alcohol content, they get a little slushy, which is perfect for OTR or blended. This cuts down on ice consumption with the drinks, and the drinks stay cold longer than if made from warm ingredients.

I usually keep a bottle of rum and vodka in there as well, just for V&Ts and rum & cokes.

[rabbi]

And all that just for what? Cold air?? Throw out these little blue things and stock up on beer in the fridge and rum & ice in the freezer.
Adding thermal mass helps very little, as it only extends cycling times.
However if you lower the setting of the thermostat at times of surplus energy supply (solar at noon, motoring, etc) you can store energy. Which you can use later by settig the temperature a bit higher, thus stopping the compressor for some time.

I remember some german guy is producing an electronic circuit to handle that for a fridge, lowering the temp to just above freezing whenever the voltage is over 13.x volts. I guess he can modify it for a freezer as well.

[Dockhead]

Originally Posted by SV THIRD DAY

But, what comes in with the air?
If only air came in...then sure...no big deal.
Just ignore it and go cruising...but my friends, the game changes when humidity comes in with the air!

The problem with Warm/moist air entering the fridge/freezer is two fold.
But the air is almost a mute point, so forget about it....it's all about the humidity!

First:
The moisture will plate out on the holding plate or thin rolled Aluminum evaporation plate. Once this frost gets over 1/4" think you start getting the Igloo affect and you dramatically decrease the efficiency of heat transfer from the Box to the holding plate/evaporator.

Second:
The humidity that comes in with the air takes BTUs to condense and phase change from a gas, to liquid, to solid...that is energy baby.

So the humidity is literally sucking up BTU energy as it condenses on your holding plate/evaporation plate AND then it kills you by making the heat transfer slower...it's a double whammy!

Air...who cares....humidity...ya...that will add to your power usage big time.

How do I know this...cruiser myth...guesses....no, from the dual test boxes running 24hrs/day at the office hooked up to a data logger and the research scientist in me that loves data and test conditions! I can measure a 30% loss in efficiency (29.7%) on identical boxes, identical test conditions with identical refrigeration systems running with the only difference being a clean holding plate/evaporation plate vs one ices up with an approximate thickness of 0.35". That's real power at the end of the day just for keeping your unit defrosted!

OK, but holding plates ice up in any case. Can you put some numbers to this idea that the humidity in the air consumes some huge amount of energy to cool down? I expect it's a complete non-issue, but it's your turn to do the math!