that the values calculated on each side of the equation provide a thermosyphon that performs in the spirit of the present invention where the term u201c substantially full u201d or the like is used herein to describe the evaporator it means that the evaporator volume i e the volume defined by the plates forming the evaporator contains a quantity of liquid coolant adequate to provide a thermosyphon that performs in the spirit of the present invention and includes a range of coolant quantities equal to or less than a completely full evaporator 0047 fig8 schematically illustrates a system 26 that conforms to this equation and has a completely full evaporator 28 when oriented as shown rotated 180 degrees from the orientation shown in fig3 the pool belt 30 must be vertically symmetric about the evaporator 28 to achieve this result when the coolant level approximately conforms to the h b h e 2 criterion in the horizontal orientation an asymmetric pool belt 30 can result in a system 26 that has a substantially full evaporator 28 only in certain orientations for example the evaporator 28 may be substantially full from a horizontal orientation through rotation to a vertical orientation but past that vertical orientation the evaporator may not be substantially full such a thermosyphon may be designed in accordance with the present invention by one of ordinary skill in the art 0048 fig9 shows a square shaped system 26 that is oriented with the limits of the evaporator 28 and condenser 30 at an angle u03b8 to horizontal the angle u03b8 is fixed by the dimensions of the system 26 and is given by the following equation u03b8 tan 1 ue8a0 l b l b l e when the system 26 is in a vertical.