Trying to get a gallon of water to chill

[Eddie_Pain]

So for the past two months I've been trying to get a gallon of water to chill to about 40-50 degrees in temp. in about 10-20 minutes. I wanted to use two TEC's(Thermal Electric coolers) attached to some heat sinks with fans expelling the heat. This would also be underneath the water/reservoir that i will buy, it will also be insulated to the best of my ability. I am wanting to know if this would work or if there is a better way of doing this. I also don't want this to be very big anything bigger than 12in*7in*6in(L*W*H) would be too big.

 

[Student100]

From what initial temperature? A 100 degrees? 60 degrees? Is the whole setup underwater? What model of thermo electric cooler?

 

[Eddie_Pain]

From what initial temperature? A 100 degrees? 60 degrees? Is the whole setup underwater? What model of thermo electric cooler?

from a room temperature of about 80 deg. F the whole setup is not underwater and a TEC Pelteir 12v 6A

 

[Student100]

from a room temperature of about 80 deg. F the whole setup is not underwater and a TEC Pelteir 12v 6A

Okay, now what kind of surface area will your reservoir have? A standard jug? Stored in a garden hose? Is there any circulation going on inside?

 

[Eddie_Pain]

Okay, now what kind of surface area will your reservoir have? A standard jug? Stored in a garden hose? Is there any circulation going on inside?

The reservoir will most likely be a size of 12in*6in*4in(LWH) and will be made out of aluminum with no circulation going on except the TEC cooling it

 

[Student100]

The reservoir will most likely be a size of 12in*6in*4in(LWH) and will be made out of aluminum

Aluminum is a poor choice. You're also probably going to want to minimize surface area as much as possible. Do you prefer rectangle geometry?

 

[Eddie_Pain]

Aluminum is a poor choice. You're also probably going to want to minimize surface area as much as possible. Do you prefer rectangle geometry?

Rectangles are just easier to build that's why i prefer them and when you said minimize SA could you elaborate what you mean

 

[Student100]

Rectangles are just easier to build that's why i prefer them and when you said minimize SA could you elaborate what you mean

1 US gallon = roughly 0.00378541 m^3, the volume of a rectangle/box/whatever that holds that amount with the least surface area is going to be ideal for this application. Set up an optimization problem and figure out the dimensions roughly.

You want a low surface area to "slow" heat transfer back into the water you're working so hard to chill. It'll also save you money on building materials.

Aluminium is not ideal because of it's generally a good conductor of heat. You should look into vacuum designs or other materials that are poor conductors of heat.

 

[Eddie_Pain]

1 US gallon = roughly 0.00378541 m^3, the volume of a rectangle/box/whatever that holds that amount with the least surface area is going to be ideal for this application. Set up an optimization problem and figure out the dimensions roughly.

You want a low surface area to "slow" heat transfer back into the water you're working so hard to chill.

Aluminium is not ideal because of it's generally a good conductor of heat. You should look into vacuum designs or other materials that are poor conductors of heat.

Would Copper be a good choice and also i didnt want exactly a gallon but just enough to fit inside of that reservoir dimension

 

[Student100]

Would Copper be a good choice and also i didnt want exactly a gallon but just enough to fit inside of that reservoir dimension

No, it's as bad as Al.

 

[Eddie_Pain]

No, it's as bad as Al.

What would you recommend

 

[Student100]

Glass, plastics? I don't know. You'd need to figure out what is safe to store water in, and ensure you aren't leaching anything dangerous into the water with the rest of the set up (TEC, circulating mechanism, etc.) Assuming it's supposed to be potable water.

 

[Nidum]

(1) Drop in a calculated quantity of ice cubes .

(2) Start with a calculated quantity premix of ice cubes and water .

(3) Either of above best guess and see what happens .

 

[NTL2009]

I'm not understanding your setup or constraints. I would use an aluminum or copper vessel and set it in an ice water bath. Provide some circulation for both.

To reduce the amount of ice required, assuming your tap water is around 60F, first cool with tap water, then cool with ice water.

The TEC might help maintain a cool temperature, but I doubt it will reduce the temperature as quickly as you want.

 

[rbelli1]

Based on your specification you need about 250W of heat transfer capability (80F to 50F in 20 minutes). A very approximate estimate of your TEC is somewhere around 50W max (100 for the pair). That will be at near zero temperature differential. At the difference you need that will be a lot less. Add non ideal insulation and your cooling device will need to be about an order of magnitude larger to get the result you desire.

BoB