Thermal Performance of Mini Flat Plate Heat Pipes for High-Power Chips

The waste heat generated by the high-power chips increases their operating temperature, reducing their performance and service life. Flat plate two-phase devices are promising cooling solutions for power electronics. Among them, the thermosyphons and pulsating heat pipes, which respectively promote the fluid circulation by gravity and oscillatory motion of liquid slugs and vapor plugs, are interesting devices to be investigated, as both show excellent heat transfer capacities. In the present work, the thermal performance of a mini flat plate thermosyphon is experimentally investigated and compared with that of a pulsating heat pipe, aiming for the thermal management of waste heat produced by miniaturized high-power chips. Both two-phase devices have the same external dimensions (100 x 55 mm2) and were manufactured by diffusion bonding technology. Distilled water was used as the working fluid. Tested in the same conditions, both operated successfully for the gravity-assisted mode; however, the thermosyphon, the lighter device, was able to transfer more heat. In the horizontal position, the pulsating heat pipe showed excellent thermal performance after the startup, working until high heat loads. In general, it was observed that the PHP became independent of gravity action for heat loads above 100 W.