They don't work well in our climate, as they rely on the evaporation of water to absorb thermal energy. If its humid, the air has little additional capacity (relative humidity) and not much heat gets absorbed. The better bet is one of the cool mist type commercial fans used at outdoor venues, bars, etc.
Of course, you are introducing lots of water into your shop as well. Money is better spent on additional south/west facing insulation and good fans.