SLM Additive Manufacturing of Oscillating Heat Pipe

This study employed metal additive manufacturing technology to fabricate oscillating heat pipes using SUS316L as the material and conducted related printing parameter experiments and thermal performance tests. The initial experimentation involved testing the relative density and size error of the metal additive manufacturing process. Density measurement was performed using the Archimedes method, and further X-ray CT scanning was utilized to observe the internal structure and compactness. The outcomes indicate that suitable laser parameters yield favorable results in producing oscillating heat pipes, achieving good compactness and minimal dimensional error with proper parameter adjustments. Following relevant pre-processing and post-processing on the oscillating heat pipe, leakage experiments were conducted to ensure experimental accuracy. The oscillating heat pipe had dimensions of 120 mm in length and 51 mm in width, with five turns of 2 mm x 2 mm cross-sectional channels inside. Interval design was employed to address inter-channel thermal interaction commonly encountered in flat heat pipes for comparison. Methanol was selected as the working fluid to investigate the oscillating characteristics and thermal performance under different input powers (20 W, 30 W, 40 W, 60 W, 80 W). The results indicated that the inter-channel spacing can significantly decrease the lateral thermal interaction and enhance the oscillation effect during the operation of the oscillating heat pipe, resulting in improved thermal performance. The experiments demonstrated that at 20 W, the equivalent thermal conductivity of the heat pipes with and without inter-channel spacing was 2428 and 1743 (W/mK), respectively, and at 80 W, it was 2663 and 2511 (W/mK), respectively. These results indicate that reducing thermal interaction can significantly improve the oscillation effect, leading to higher equivalent thermal conductivity at low power.