A novel surfactant material for performance enhancement on nucleate pool boiling heat transfer

Long-chain surfactants have been extensively studied for boiling enhancement, while the investigation of steroid surfactants is limited. In this study, steroidal bile salts were experimentally attempted for nucleate pool boiling enhancement on flat copper surface. Four types of bile salts were found effective in improving heat transfer coefficient (HTC) in aqueous form, with SDC having the most significant effect, followed by SHDC, SC, and STGC. The STGC deposited surface exhibited a simultaneous improvement of critical heat flux (CHF) and HTC with long-term repeatability. The enhancement mechanism is discussed by means of solution properties, bubble behaviors and surfactant molecular structure. Both aqueous and deposited bile salts show considerable boiling performance with existing materials, with better safety characteristics. The findings of this study can provide a bio-friendly approach to surfactant-aided energy conversion applications and contribute to the development of new-generation green surfactant materials.