EFFECT OF ASPECT RATIO AND FILLING RATIO ON THERMAL PERFORMANCE OF AN INCLINED TWO-PHASE CLOSED THERMOSYPHON

In this paper the effect of the aspect ratio and filling ratio on the thermal performance of an inclined two-phase closed thermosyphon under normal operating conditions has been investigated experimentally. The experiments were carried out for filling a ratio range of 20%≤F.R≤60% and aspect ratios of 15, 20, and 30 for an inclination angle range of 15°≤Φ≤90°. The thermosyphon was manufactured using a copper tube with an inside and outside diameter of 14 and 16 mm respectively, and a 1000 mm length. Distilled water was used as the working fluid. The heat transfer rate, temperature distribution, and condensation heat transfer coefficient of the inclined two-phase closed thermosyphon were measured. The results showed that the maximum thermal performance of the thermosyphon occurred at 60° for all three aspect ratios and several filling ratios. The thermal performance of the inclined thermosyphon with an inclination angle of 60° was better for a filling ratio of 45%. It was also found that a higher condensation heat transfer coefficient for all three aspect ratios took place between 30 and 45 degrees.