Effect of SiO2 super-hydrophobic coating and self-rewetting fluid on two phase closed thermosyphon heat transfer characteristics: An experimental and numerical study

Abstract

The realization of the importance of high-performance heat transfer units, in this case a two-phase closed thermosyphon (TPCT), has gained a foothold in recent years. To this end, the super-hydrophobic coating has been applied in the TPCT condenser surface and 1-Butanol is added as a self-rewetting aqueous solution in the working fluid. The super-hydrophobic coating has been created by using surface engineering and synthesis super-hydrophobic SiO2 nanoparticles. In this work, in a bid to measure some well-established parameters (heat input, filling ratio, and coolant mass flow rate) which are capable of getting thermal efficiency and resistance surging toward desirable numbers, experimentally considered TPCT implement. In order to illustrate boiling and condensation phenomena, the numerically simulation have been conducted assists by volume of fluid (VOF) multiphase model and user-define function (UDF) house code. Results indicate that in the heat input of 250 watts, the condenser convective heat transfer coefficient of TPCT with super-hydrophobic coating is 13.34% higher than the TPCT with non-modified condenser. Also, increasing heat input, filling ratio and 1-Butanol mass concentration decreases the TPCT thermal resistance opposite of the coolant mass flow rate. The numerical simulation illustrates that the boiling in a TPCT with 1-Butanol-water working fluid has occurred faster than TPCT with water working fluid. Also, the condensation has been appeared droplet due to high contact angle in the condenser with super-hydrophobic coating.