The impact of gravity on the performance of pulsating heat pipe using surfactant solution

Using surfactant aqueous solution as working fluid may provide an efficient method to weaken the impact of gravity on the performance of Pulsating Heat Pipe (PHP). The Cetyl Trimethyl Ammonium Bromide (CTAB) was selected for preparation of surfactant aqueous solution in this work. For comparison, an experimental study was conducted to investigate the operation performance of a PHP charged with deionized water and CTAB solution, respectively. The results indicate that the heat transfer capacity of water PHP is clearly decreased and even lost without the assistance of gravity. However, the CTAB solution PHP shows less rely on gravity due to their higher wettability and better boiling heat transfer characteristic. Furthermore, the CTAB solution PHP presents a better thermal performance than the water PHP under the same condition. At the input power of 100 W, the thermal resistances of CTAB solution PHP are decreased by 5–51% than the water PHP when inclination of PHP varies from horizontal to vertical orientation.