the pot is located lower than any other point of the sealed system this relationship is also true in the shelf structure shown in fig2 since the bracket 30 will always be below the front edge of shelf 28 however in some locations where liquid flow may be desired in both directions or where it is necessary to locate the collection pot higher than the condenser section the system could be made operable by the use of a wick means such as wick 34 many materials and structures can be utilized by this wick but the main concept is basically that of capillary flow this phenomenon is caused by the surface tension of the liquid refrigerant when flowing through very narrowly restricted areas to an extent the capillary flow will be strong enough to overcome gravitational force in the opposite direction the wick can be a small tubing or merely a meshing or the like and can be located along the inside walls of the refrigeration tube or down the center of the tube depending on structural convenience the theory is basically that of standard capillary flow the choice of refrigerant is important since the chosen liquid must have a boiling point under atmospheric conditions which is below the lowest possible operational temperature of the system for example water would provide an excellent refrigerent if the operational temperature of the system would never go below 212 u00b0 f also critical is the volume of refrigerent placed in the system when initially charged preferably enough refrigerent is used such that in the steady state the surface level of liquid refrigerent in pot 12 is above the sensing well 22 and below the inlet and outlet ports 14 and 16 while.