Heat transfer characteristics and optimization of the efficiency and thermal resistance of a finned thermosyphon

Highlights: • Experimental analysis on longitudinal fin assisted thermosyphon is performed. • Quantitative correlations are proposed for thermal resistance and efficiency. • An optimization procedure is conducted to find the best thermal performance. • Applying more fins reduces the thermal resistance and enhances the efficiency. • Optimum thermal resistance and efficiency are 0.168 °C/W and 93.89%, respectively. In the present work, the performance enhancement of a two-phase thermosyphon is investigated utilizing longitudinal fins on the outside of the condenser. The Central Composite Design is used for designing the tests and analysis of variance is conducted to evaluate the contribution percentage of the operating factors on the system performance. The operating factors of the current analysis include the heat input, filling ratio, coolant flow rate, and fin numbers. Moreover, thermal resistance and efficiency of thermosyphon are regarded as the system responses. Further, an optimization procedure by Response Surface Methodology is employed to obtain the optimum values of operating factors, which results in the best system performance. Based on Response Surface Methodology, empirical quantitative correlations are presented for both thermal resistance and efficiency. Results indicate that augmenting the heat input, filling ratio, and fin numbers lowers the thermal radiation, while accelerating the coolant raises it. Moreover, raising the filling ratio and the coolant flow rate enhance the efficiency. It is concluded from the optimization procedure that the lowest thermal resistance of 0.168 °C/W and the highest efficiency of 93.89% are obtained under the optimal condition of 270.292 W of heat input, 70% of the filling ratio, 250 ml/min of the flow rate, and 8 fins.