Dear Ben et al
I am new to your show having just come across it on my new Roku XDS.
I really enjoyed your show re peltier devices and cooling lemonade cans but then noticed that your cooler directly connected to the can's surface. Hmmm...
It struck me that there might be a better way to do this. If you were to make the can holder a bit bigger and wider there would be room around the can to have some liquid. The cooled liquid would make better contact with the surface of the can and thus would transfer heat more effectively (at least that's my theory).
Ah, but I hear you say, the liquid will freeze, and you would be quite correct. The answer to this is to make the liquid very very salty. I recall studying a bit about the triple point of water and how adding salt lowers its freezing temperature. That is of course why they put salt on roads in Canada in winter.
Could you humour me with this theory and get two of your coolers, one original and another modified as I have suggested above and see whether in fact the salty brine solution surrounding the can helps cool it quicker. You can easily test this by opening both cans and putting a temperature gauge in each whilst doing the test.
To make the exercise more fun I suggest you instead use two cans of Australian beer and drink the beer thereafter.