Experimental Investigations on Effect of Orientation on Thermal Performance of a Novel Phase Change Material-Based Heat Sink

As electronic devices generate heat while operating, thermal management is important in view of the reliability and lifespan of the device. Much research is focused on the improvement of charging time for continuous operations of the device. Moreover, for intermittent operation of devices, the reduction in the discharging time is also as essential as the improvement in the charging time. Therefore, the objective of the study is to develop a strategy that improves charging time and reduces discharging time. This paper reports the experimental heat transfer results of a novel phase change material (PCM)-based heat sink coupled with a heat pipe under different orientations. The experiments are conducted at a constant fill ratio of 99% on several heat sink configurations, such as a heat sink (i) with the stem at the center, (ii) with four fins, and (iii) with three longitudinal fins coupled with a heat pipe. The aluminum-made heat sink having an outer diameter of 58 mm and a height of 55 mm with a wall thickness of 4 mm, is used for all the heat sink configurations. The heat pipe with an evaporator length of 60 mm and a condenser length of 40 mm is attached at the center of a three-fin heat sink configuration. Experiments are performed on different heat sinks with n-Eicosane as PCM at different orientations of 0 deg, 45 deg, 90 deg, 135 deg, and 180 deg at various power levels. The heat input is varied between 6 W and 12 W. The condenser section of the heat pipe is cooled under two different conditions, i.e., (i) natural convection and (ii) forced convection. The results show that the finned heat sink coupled with a heat pipe (FHSHP) gives the best charging and discharging performance compared to other configurations. Moreover, it is observed that the performance of an FHSHP is orientation-dependent. Furthermore, the overall effectiveness of FHSHP is high when the condenser section of the heat pipe is cooled using forced convection rather than natural convection.