An experimental investigation on the evaporation and condensation heat transfer of two-phase closed thermosyphons

Two-phase closed thermosyphons (TPCTs) are excellent thermal transfer devices that their integration into heat exchangers has been shown a strong potential for energy savings. The scope of this study is an experimental evaluation of the evaporation and condensation heat transfer of a TPCT for uniformly heated evaporator surface. Water as the working fluid is charged in a TPCT with a length of 500 mm and an inner diameter of 33 mm at different filling ratios (8-100%). The Thermosyphon heat transfer performances are compared with some predictive correlations of suppress the pool boiling insert uniquely and suppress the pool boiling combined with film evaporation for the evaporator section at different filling ratios. The experimentally obtained condensation heat transfer is also evaluated by available filmwise condensation model. Results show an agreement with the most of the selected correlations with tolerance ±30% and the appropriate set of correlations are introduced giving an accuracy within ±10%.