“…In the past several names have been put forward to identify devices of this kind: "down-pumping heat pipes" [13], "reverse thermosyphon" [14], "passive vapour transport systems" [15], "spontaneous downward heat transport systems" [16] and so on . In my opinion, the best name for identifying these particular devices is periodic two-phase thermosyphons (PTPT), because they can operate with the evaporator located either above or below the condenser, they can be seen as a special version of a heat pipe or, more precisely, a two-phase thermosyphon and, lastly, they all operate in a periodic heat transfer regime.…”