Effect of Surface Biphilicity on FC-72 Flow Boiling in a Rectangular Minichannel

Akam Aboubakri,Abdolali K Sadaghiani,Ali Kosar,Suleyman Celik,Vahid Ebrahimpour Ahmadi,Khellil Sefiane

doi:10.3389/fmech.2021.755580

Akam Aboubakri, Abdolali K Sadaghiani + Show 4 more

Open Access

https://doi.org/10.3389/fmech.2021.755580

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Abstract

Flow boiling is one of the most effective mechanisms in heat transfer thanks to the latent heat of vaporization. Surface modifications such as mixed-wettability have a considerable effect on the boiling heat transfer performance in terms of enhancement in boiling heat transfer as well as critical heat flux. This study introduces a new method of fabrication of biphilic surfaces, where C4F8 (Octafluorocyclobutane) islands are surrounded by silicon. Two different biphilic surfaces were fabricated and compared with the entirely uniform hydrophobic surface taken as a reference,. Each of the biphilic surfaces has three different sections, namely inlet, middle and outlet regions. The first region is mainly hydrophobic (inlet), while the third region is mainly hydrophilic (outlet). The heat transfer coefficients were obtained at different heat fluxes. Compared to the entirely uniform hydrophobic surface, the results show that biphilic surfaces enhance the boiling heat transfer performance by up to 50%. The visualization results revealed that the biphilic surfaces lead to more nucleation sites in the bubbly flow regime and break up the elongated bubbles in the slug flow regime.

Highlights

With the decrease in the size of ICs and increase in their power density, new methods for heat dissipation become inevitable to maintain the working temperature below a critical value
This study investigates the effect of surface mixed wettability on flow boiling of FC-72 in a rectangular minichannel
Surface mixed wettability is an effective method for BHT enhancement especially effective for coolants with smaller surface tension and latent heat of vaporization

Summary

INTRODUCTION

With the decrease in the size of ICs (integrated circuits) and increase in their power density, new methods for heat dissipation become inevitable to maintain the working temperature below a critical value. In the study of Kim et al (Kim et al, 2018) on the effect mixed wettability surfaces in flow boiling of water, it was shown that hydrophobic stripes, regardless of their direction with respect to the flow direction, provided active nucleation sites. They concluded that merging and confinement of the bubbles are the major mechanisms enhancing boiling heat transfer. Even though pool boiling heat transfer on purposefully modified surfaces has been investigated by many researchers, flow boiling on biphilic surfaces needs further studies. 100°C 997 kg/ m3 0.59 kg/ m3 0.0720 N/ m 4.13 kJ/ kg K 2442 kJ/ kg 0.606 W/ m K 0.89 mPa s

Experimental Procedure

AND DISCUSSION

CONCLUSION

Findings

DATA AVAILABILITY STATEMENT