Cooldown Characteristics of a Neon Cryogenic Pulsating Heat Pipe

The cooling capacity of the cryogenic pulsating heat pipe (PHP) during the cooldown process is one of the critical factors for it used as the thermal link in the cryogenic system. In this paper, the copper block with a mass of 7.69 kg is cooled by a cryogenic PHP using neon as the working fluid. The heat transfer mechanism of the cryogenic PHP during the cooldown process is analyzed. Effects of the condenser temperature and the liquid filling ratio on the cooldown characteristics of the cryogenic PHP are studied. An optimized cooldown process of the cryogenic PHP is proposed and the cooldown performance is predicted. For the copper block cooled from 250 to 40 K, the average cooling capacity of the cryogenic PHP with the optimized cooldown process is 24 W, which is 4.5 times more than that using the high purity copper rod with the same cross-sectional area.