Experimental Investigation of Boilingand Condensation Heat Transfer Ofatwo Phase Closed Thermosyphon

In this paper the heat transfer characteristics of a two-phase closed thermosyphonover a wide range of heat transfer rates, system pressure, aspect ratios and filling ratioswere studied. the experiments focused on the boiling and condensation heat transfercharacteristics of the thermosyphon. the experimental boiling and condensation heattransfer coefficients inside the thermosyphon were compared with the existing correlations.a good agreement between the experimental results of condensation heat transfer of thethermosyphon and nusselt's correlation was obtained. in addition, the optimal workingfluid filling and the overall heat transfer coefficient were evaluated for practical operation.finally, according to poor agreement between the experimental results of boiling heattransfer coefficient and existing correlations, the working conditions were analyzed and anew practical formula (correlation) was presented. the new correlation can be used topredict boiling heat transfer coefficient generally.