Simin Soltani Ghaleh - MSc., School of Mechanical Engineering, University of Tehran, Tehran, Iran
MohammadAli Akhavan-Behabadi - Professor, School of Mechanical Engineering, University of Tehran, Tehran, Iran
Seyyed Farshid Chini - Associate Professor, School of Mechanical Engineering, University of Tehran, Tehran, Iran
Behrang Sajadi - Associate Professor, School of Mechanical Engineering, University of Tehran, Tehran, Iran

In the present study, heat transfer enhancement during the boiling flow of refrigerant HFO-۱۲۳۴yf by inserting aluminum and superhydrophobic aluminum twisted tape has been experimentally investigated. The boiling flow of refrigerant was in a copper tube with the length of ۱ m, the outer diameter of ۱۳ mm and the inner diameter of ۱۱ mm in the condition of the constant heat flux of ۱۲۰ W with the presence of two types of twisted tapes, i.e. aluminum and superhydrophobic aluminum twisted tapes, each in four twist ratios of ۶, ۹, ۱۲ and ۱۵, at mass velocities of ۳۰, ۵۰, ۷۰ and ۹۰ kg/m۲s and in vapor qualities of ۰.۱۵ to ۰.۸۵ with ۰.۱ intervals. The results show that the presence of any type of twisted tape with any type of surface property increases the heat transfer coefficient; this phenomenon is continuously increased by increasing the mass velocity and decreasing the twist ratio. At low mass velocities, unlike high ones, the heat transfer coefficient decreases with the increase in vapor quality. The highest and lowest heat transfer enhancement is respectively ۴۲.۲% for the aluminum twisted tape with a twist ratio of ۶ and ۲.۳% for the super-hydrophobic aluminum twisted tape with a twist ratio of ۱۵, compared to plain tube.

Twisted tape, Super-hydrophobic, Boiling, Refrigerant ۱۲۳۴yf, Empirical