Effect of anodization on the heat transfer performance of flat thermosyphon

This paper presents the thermal performance of a flat thermosyphon with and without anodized inner surface. Anodization is performed to prepare a uniform coating on the inner side of the thermosyphon. Both non-anodized and anodized thermosyphons charged with acetone and tested in the heat input range of 50-300 W. Experiments are conducted for anodized and non-anodized flat thermosyphons at various inclination angles (0°, 45°, 90°) and fill ratios (40%, 60% and 100%). It is found that fill ratio and inclination angle has a significant effect on the performance of the thermosyphon. The total thermal resistance of the anodized thermosyphon is reduced by 20% when compared to the non-anodized thermosyphon. The pore density of the anodized surface has increased almost 90% than the pore density of non-anodized surface. Both evaporator and condenser heat transfer coefficient of anodized thermosyphon is enhanced, when compared to that of non-anodized thermosyphon. The maximum enhancement in heat transfer coefficients of the evaporator and condenser in the anodized thermosyphon is 9% and 27% respectively, when compared to non-anodized thermosyphon at a heat flux of 49 kW/m2. The performances of flat and cylindrical anodized thermosyphons are compared and it is found that the flat thermosyphon performed better than the cylindrical one. The heat transfer coefficient in evaporator and condenser of flat thermosyphon is enhanced to 69% and 56% respectively when compared to the cylindrical one at a heat flux of 50 kW/m2.