Pool boiling performance of enhanced tubes on low GWP refrigerants

• Published in: Applied thermal engineering Vol. 123; pp. 791 - 798
• Main Authors: Byun, Ho-Won, Kim, Dong Ho, Yoon, Seok Ho, Song, Chan Ho, Lee, Kong Hoon, Kim, Ook Joong
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2017; Elsevier BV
• Subjects: Enhanced tube; Flooded evaporator; Global warming; Heat flux; Heat transfer; Heat transfer coefficients; Hydrofluorocarbons; Low GWP refrigerants; Pool boiling; Refrigerants; Refrigeration; Tubes; Wilson plot; Low GWP refrigerants; Flooded evaporator; Pool boiling; Wilson plot; Enhanced tube
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2017.05.009

•Pool boiling heat transfer performance of low GWP refrigerants was investigated.•The HTCs of low GWP refrigerants were compared with empirical correlations.•The enhanced 2 tube is effective for low pressure R-1233zd(E). Low GWP refrigerants have drawn increasing attention as an alternative to HFC refrigerants that are regulated as a leading cause of global warming. The present study was focused on R-1234ze(E) and R-1233zd(E) refrigerants among other alternative refrigerant candidates and experimented on three types of tubes, i.e., a plain tube and two type of enhanced tubes, in terms of pool boiling heat transfer performance. The investigation was conducted under the experimental condition at saturated temperatures 4.4°C and 26.7°C and heat flux of 10–50kW/m2. The heat transfer coefficients of R-1234ze(E) and R-1233zd(E) for the plain tube showed approximately 10.8–19.0%, 54.1–62.8% lower than those of R-134a respectively. Also, the results were compared against the previous empirical correlations, which proved satisfactory predictability for all conditions. For the enhanced 1 tube, the heat transfer coefficients of R-1234ze(E) and R-1233zd(E) showed 9.8–14.0%, 60.0–75.0% lower than those of R-134a, while the heat transfer coefficients of R-1234ze(E) and R-1233zd(E) for enhanced 2 tube showed 13.3–17.9%, 39.5–43.7% lower than those of R-134a respectively.