They aren't passive but only dump heat into ambient temperature. Which I thought is the bit you objected to.
Actually they use evaporation not just ambient temperature.
Explanation starts at ~minute 4. https://www.youtube.com/watch?v=tmbZVmXyOXM
Actually they use evaporation not just ambient temperature.
Explanation starts at ~minute 4. https://www.youtube.com/watch?v=tmbZVmXyOXM