What you want old son is what we scientists call the "latent heat of evapouration". It's got nothing to do with being secretly bent, and everything to do with keeping your beer at a drinkable temp. We tried this method last year on a barrel of home made Old English ale that one of our idiots brought along. This method works on the same principle as to why it is so f**k*ng cold when you get out of the sea on a red hot day.
Here's what to do. Get your wine or beer barrel/cans/bottles, stack them up and cover them in a couple of towels. Stand them right in the sun. Yes, as hot as it gets. Immediately soak the towel in water. Our barrel was stood on a BBQ base to assist air flow. The lovely sun evapourates the water creating a cooling effect, the stronger the sun, the colder the beer. NB Keep the towel wet at all times.
Our Old English ale was beautifully chilled to a very drinkable temperature, not quite ice cold but just right for real ale. However, it still tasted like the waste residue from the Marmite factory and not surprisingly, gave us foul hangovers and diarrhoea.
Andy Z