Flow boiling of carbon dioxide: Heat transfer for smooth and enhanced geometries and effect of oil. state of the art review

• Published in: International journal of refrigeration 2019-12, Vol.108, p.311-335
• Main Authors: Mastrullo, R., Mauro, A.W., Viscito, L.
• Format: Article
• Language: English
• Subjects: Boiling; Carbon dioxide; CO2; Correlation analysis; Data points; Enhanced tubes; Flow boiling heat transfer; Geometry; Heat conductivity; Heat exchangers; Heat transfer; Heat transfer coefficients; Heat transfer with oil; Lubricants; Méthodes prédictives; Prediction methods; Review; State-of-the-art reviews; Statistical analysis; Synthèse; Transfert de chaleur avec huile; Transfert de chaleur par écoulement en ébullition; Tubes; Tubes améliorés
• ISSN: 0140-7007; 1879-2081
• DOI: 10.1016/j.ijrefrig.2019.08.028

•Collection of boiling data for pure CO2 and with CO2/lubricant mixtures.•Effect of operating conditions and oil presence on the heat transfer analyzed.•Data in smooth tubes sorted and analyzed according to their flow pattern.•Experimental data compared to only-convective and only-nucleative heat transfer.•Flow boiling HTCs in smooth tubes accurately predicted by fang et al. correlation. This paper presents a state-of-the-art review on flow boiling of carbon dioxide, including experimental studies and correlations for smooth and enhanced tubes, with pure CO2 and CO2/lubricant mixtures. Specifically, 5223 CO2 heat transfer coefficient data in smooth tubes are collected, and the effect of the operating conditions is discussed. Additional 883 data points in microfin tubes and 1184 experimental heat transfer coefficients in smooth tubes with CO2/oil mixture are also collected, and the influence of the microfin structure and of the oil presence on the heat transfer mechanism is analyzed. The statistical analysis has highlighted that the CO2-based correlation of Fang et al. is very accurate (MAE  =  5.1%) for the smooth tube database, whereas the heat transfer coefficients in microfin tubes are satisfactorily predicted (MAE  =  30.5%) with the model of Mehendale. Among the available correlations for CO2/oil mixture in smooth tubes, the method of Gao et al. provides the highest accuracy (MAE  =  63.2%).