Comparative numerical investigation of thermal performance in two-phase closed and loop thermosyphons

초록

Loop thermosyphons have been previously reported to exhibit superior performance; however, there is no existing literature directly comparing their thermal performance with that of closed thermosyphons. Therefore, this study conducts a three-dimensional numerical investigation to compare the thermal performances of closed and loop thermosyphons across a power range of 100-300 W and filling ratios of 50-150%. A multiphase volume of fluid model is employed with water vapor and liquid water as the primary and secondary phases, respectively. Moreover, the evaporation-condensation model is applied to account for multiphase boiling and condensation, whereas the k-& varepsilon; turbulence model is used to capture turbulent fluctuations. The numerical results were validated against several published thermosyphon studies. The best thermal performance for both types of thermosyphons was observed at a filling ratio of 150%, which yielded the lowest thermal resistance. The closed thermosyphon performed better up to 200 W. In contrast, the loop thermosyphon exhibited lower resistance at 300 W. The present study provides guidelines for comparing and selecting a suitable thermosyphon among closed and loop vertical thermosyphons.

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