It is well known that evaporative cooling (EC) is not very suitable for humid climates. EC is however, the least costly of common (active) cooling techniques. As a native of Florida, I have spent many hours researching how to make EC applicable in the humid southeast US. There are two primary obstacles to employing EC in the southeast. Additional (and undesirable) moisture in living spaces is the most notable disadvantage when IC is attempted in humid climates. However, the greatest limitation is the lack of sufficient wet bulb depression at night. Many people are of the opinion that the relative humidity (RH) in the southeast is too great. This is true – but, mostly at night. Most of the region has sufficiently low RH during the day – around 50% to 60% RH midday. This is low enough to yield wet bulb temps 10 to 12 degrees lower than ambient dry bulb. This is significant cooling, but pointless if it can only be accomplished during the day, as nighttime temps in the summer are higher than the human comfort range.
I constructed and tested a sub-scale EC prototype that I believed has a good chance of defeating the limitations associated with EC in the southeast US. The prototype was a novel EC configuration that addressed the issue of insufficient wet bulb depression by decentralizing the evaporator and employing a high mass evaporative medium within the walls and floors, namely lava rock gravel. I dubbed the system Integrated Evaporative (IE) cooling. Lava rock gravel serves a triple role in the system: Firstly, it is the water containment vessel. Secondly, it is the evaporative medium. Finally, lava rock serves as the heat transfer medium. Wet lava rock has an extraordinarily high thermal capacity. This feature in conjunction with the high volume of wet lava rock within the floor and walls provides very high thermal mass. High thermal mass affords a pronounced “cave effect” – allowing the system to "coast" over idle (nighttime) periods. Running the system only during the day is a doubling of cost savings. Additionally, the prototype resolved the issue of unwelcomed additional moisture in living spaces by exhausting the moisture-laden process air outside the dwelling. A bonus effect of “dynamic insulation“ is provided by the IE configuration. It is generally agreed that solar radiation is the greatest source of heat within the interiors of dwellings. The evaporator within the walls and floor of the IE system provides a 100% effective thermal barrier to infiltrating heat through the walls and floor.
The IE prototype has demonstrated a genuine potential to employ evaporative cooling in hot and humid climates. More details as well as videos, photos, drawings and charts are available at my personal website (spam-free). I am reluctant to reveal the URL as it may be a violation of policy for initial posts. I hope that I get replies to this post (affirmative or negative) and I believe I will be permitted to provide my website address in follow-ups to any replies.