The Porticool Personal Cooling System (PCS) is a non-electrical active
cooling garment based on the endothermic expansion of a
liquefied atmospheric gas. The concept is referred to as the
Personal Cooling System (PCS).
The
Porticos PCS employs an innovative mass-transport strategy to
remove heat from the body and reject it to the ambient
environment. It is a two-stage process, each stage removing
heat from the body in a different way.
In
stage one, liquid CO2 travels through fine
tubing, undergoing a continuous pressure drop towards
atmospheric pressure. As this happens, the liquid will flash to
vapor, absorbing energy equal to the heat-of-vaporization for CO2:
about 101 BTU/lb.
It
stage two, the newly-vaporized CO2 is allowed to
vent over a thin, absorbent textile layer in contact with the
skin. The gas is cool and dry; a perfect medium for natural
evaporative cooling. As perspiration evaporates, it must draw
heat from the body equal to the heat-of-vaporization for water:
about 970 BTU/lb. Heat and moisture are then expelled from the
system with the gaseous CO2.
Due to the
viscosity of CO2, the tubing can be made extremely thin. Thus,
use of this technology results is an efficient, lightweight and
flexible garment which satisfies all of the stated criteria. The
level of cooling can be easily controlled and the cooling
duration can be customized via the size of the tank or simply
and easily replacing the tank during a mission.
