I haven't seen this around and am curious if anyone has any experience with intermitant ammonia evaporative cooling? In particular I've been looking at something called a "Crosley icy ball" no moving parts and completly self contained other than a heat source. Having looked into the servel refrigeration cycle and finding it lacking in its ability to produce anything like a usefull amount of ice, I found the crosley system to be capable of well below freezing temps and am planing to build one, just wondering if anyone has any tips or recomendations. Strikes me as an excellent tool for bad times. I really like the no electric power / no propane needed part.