VR-ZONE have an interesting article on building a dual-evap phase cooler, with a single compressor. Extensive photographs and instructions are given. You will have to read the article to find out just how cold things get, but believe me - its cold! The article uses 1HP Toshiba Rotary Compressor for R22. Whilst the article is a little short on words (bit like this news post!) it more than makes up for it with first class pictures.