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Tempratech Self-Cooling Can
r.future writes "I saw on Gizmodo that a company called Tempratech has created an 100% safe and environmentally friendly aluminum can that uses a self-chilling process involving a cooling gel, desiccant, and heat sinks, to chill itself. The self-contained I.C. Can is the approximate size of a 500 mL beverage can. This includes the beverage container itself, and the integral self-chilling device, and according to Tempratech the can is 'proven to lower beverage temp by a minimum of 30 degrees Fahrenheit in only three minutes.'"
For those of us in the US:
Google has the conversion.
500 ml = 16.9070113 US fluid ounces
Self-Chilling I.C. Can
(filed under gadgets) Speaking of cold beverages, Tempra Technology has developed the I.C. Can, a "100% safe and environmentally friendly" aluminum can that uses a self-chilling process involving a cooling gel, desiccant, and heat sinks. They claim to be able to drop the temperature of the 10-ounces of beverage inside by 30 degrees Fahrenheit in three minutes. It's pretty cool tech, but I can't help but wonder if it's all a bit convoluted. That doesn't mean I don't want to try one; unfortunately, Tempra is still looking for a partner to actually put a branded beverage inside. (Thanks, JEB!)
FROM THE MANUFACTURER'S WEBSITE:
Ingenious.
The I.C Can(TM) is the result of the solid partnership of Tempra Technology and Crown Cork & Seal, who are currently discussing commercialization and marketing of this self-chilling can to top beverage companies. Imagine: an icy cold beverage without refrigerated vending machines or bulky ice chests.
The world's first self-chilling can is finally here! It works. It's safe. And it's development is nearing completion now through the partnership of Tempra Technology and Crown Cork & Seal.
The advanced design utilizes the latest breakthroughs in thermal, insulating and vacuum heat pump technology. The self-contained I.C. Can(TM) is the approximate size of a 500 mL beverage can. This includes the beverage container itself, and the integral self-chilling device.
Proprietary engineering creates a temperature drop proven to reduce the I.C. Can's(TM) contents by a minimum of 30 Fahrenheit (16.7 C) in just minutes. When activated, the all natural desiccant contained within a vacuum draws the heat from the beverage through the evaporator into an insulated heat-sink container. It is this patented vacuum-power which lowers the temperature so dramatically and quickly, leaving the beverage inside cool and refreshing.
And it's safe! I.C. Can's(TM) innovative design is 100% safe and environ- mentally-friendly; easy to operate, store and transport. The self-contained I.C. Can(TM) uses no carbon dioxide, CFC, HFC, or any other compressed gases and is totally non-toxic, without risk of gas or vapor escape.
As Tempra Technology and Crown Cork & Seal continue to finalize development of the self-chilling I.C. Can(TM) for mass production, we'll also innovate new cutting-edge technologies for other applications in the beverage industry.
To learn more about the exciting - and very real - I.C. Can(TM), call 1-877-TEMPRA-1.
The problem with rapid cooling of carbonated drinks is that the solubility of CO2 in water decreases at low temperatures. And at high temperatures, the rate of de-sorption increases, just for kicks. It's a wonder any stays in the water at all.
Anyway, the ideal aim for speed cooling is to drop the temperature down to 'cold but drinkable' as rapidly as possible. Going below that temperature is as bad as not going cold enough.
As you noted, you need to get a rate of cooling such that the rate that gas is forced out of the drink is sufficently low.
What, then, is the rate of cooling? Well, it turns out (insert handwave here) that the rate of heat flow is determined by the difference in temperature. To a first approximation *handwave*, then, we can asses the rate of cooling by the temperature difference between drink and cooling medium.
Liquid nitrogen (LN2) is at 77 K. Room temperature is 298 K, giving a temperature difference of 220 K [0]. For comparison, the temperature difference between ice and room temperature (the annoyingly warm temperature soft drinks tend to be at) is 25 K. Thus we can consider that the rate of cooling from liquid nitrogen is about 10 times faster than from ice [1].
How long does it take to cool a soft drink with ice? Well, in my experience, about 20 seconds for around 330ml, with gentle agitation (i.e. a quick stir, or pouring over the ice). Thus the 'few seconds' the poster give for LN2 to hit freezing point is qualitativly correct [2].
The temperature of dry ice is 195 K, which gives around 125 K difference [3], thus an initial cooling rate around 5 times the heat transfer rate of ice, and half that of LN2. It's not quite, because thermal contact is better with the other two cases (liquid - solid interface, versus solid - solid for the dry ice [4]).
You could put the dry ice in the drink, or the LN2 in the drink. The problem with that is that if you drop the cold material in the drink, it might sink under the surface, flash freeze the surrounding liquid, and then turn to gas. This risks the ice exploding (and is more of an issue for dry ice than LN2).
The simplest way to avoid these problems is use enough coolant to get your drink down to ideal temperature, so that the whole mass of liquid will not freeze, always leaving a path for gas escape.
How much is that? Well, an estimate may be made as follows: If we assume that the coolant material are at the temperature of boiling/sublimation as appopriate, then the total energy absorbed per unit mass will be equal to the apporiate latent heat [5]. This allows a calculation of the mass required, if the total energy tobe removed from the drink is known.
If we assume [6] that the specific heat capacity (amount of heat energy taken to change the temperature of a substance) of the drink is equal to that of water, that gives a value of 4.2 kJ K-1 kg-1. Further, we assume that it's density is also equal to that of water, so that 1ml equals 1 g.
The appropriate specific latent heats for our coolants are: 199 kJ kg-1 for nitrogen and, surprisingly, 199 kJ kg-1 for CO2. I think that that great cosmic coincidence is proof that this sort of calculation is intended to occur.
Thus, to remove 25 K from 330ml of water, we need to remove 20 * 330 * 4.2 J = 27.7 kJ, if we take the desirable temperature of the drink to be 5 degrees centigrade. That's about 140 grammes of coolant.
The density of solid CO2: 1562 kg/