Safe Endothermic Reaction

[will123]

I have a need to temporarily keep a liquid cool where there is no available external power supply. For this particular application making use of an endothermic reaction would be a good solution. But I would like for it to be safe. A couple of possible reactions is to dissolve Potassium or ammonia chloride in water. Is anyone able to suggest alternative reactions that require more energy and therefore be more efficient, but still use 'safe' chemicals?

Apologies if this request is not clear, but I am no chemist - if you need further information let me know and i will elaborate.

Thank you in advance for your assistance.

 

[moltenmetal]

Hmmm- what about melting ice? Waste disposal will be a lot easier that way than any chemical reaction you might choose to use.

 

[zdas04]

Or sublimating dry ice?

 

[IRstuff]

A Thermos and some blue ice

TTFN

 

[ApC2Kp]

will123,

Vaporization of liquified gases would probably provide sufficient cooling for moderate amount of liquid. The disposal issues could be more easily taken care of for a liquified gas like carbon dioxide or nitrogen. The use of propane, butane, or ammonia would require burning, processing, or recovery of vapors. Fluorocarbons would be prohibitive from a cost and environmental aspect.

There are small compressed air units (Vortec tubes) that are used for some instrument cabinet cooling applications.

http://www.exair.com

and discussed in thread391-91020.

 

[Ashereng]

I am thinking along the lines of IRstuff.

A lot of insulation means less cooling required.

The dry ice and liquid nitrogren would certainly be "safe" chemically, depending on amount - but handling will be more hazardous than simply ice (frozen water).