Researchers at the Chinese Academy of Sciences and other laboratories in Beijing, China discovered why the spines of the cactus Opuntia microdasys are so efficient at capturing fog droplets:
Although the research looked at fog droplet capture by the cacti, the findings are applicable to surfaces chilled by mechanical refrigeration (evaporator coils) or by a liquid coolant (chiller coils). If the cacti spine attributes can be mimicked on the coil surfaces, condensate will drain more quickly from the coil. Rapid draining minimizes the presence of an insulating water film on the chilled surfaces. This promotes additional condensation per unit time which increases liquid water production rate of the water-from-air system (atmospheric water generator).
- spine tip is has oriented barbs;
- Conical form of barbs increases water harvesting area;
- Conical form causes water droplets to flow to spine base; and
- Spine grooves become less rough near the spine base, setting up a force pushing water towards the base.
Although the research looked at fog droplet capture by the cacti, the findings are applicable to surfaces chilled by mechanical refrigeration (evaporator coils) or by a liquid coolant (chiller coils). If the cacti spine attributes can be mimicked on the coil surfaces, condensate will drain more quickly from the coil. Rapid draining minimizes the presence of an insulating water film on the chilled surfaces. This promotes additional condensation per unit time which increases liquid water production rate of the water-from-air system (atmospheric water generator).
