Experimental investigation of condensation flows in circular cross-section channel

• Published in: Applied thermal engineering 2018-12, Vol.145, p.147-154
• Main Authors: El Achkar, Georges, Queeckers, Patrick, Iorio, Carlo Saverio
• Format: Article
• Language: English
• Subjects: Circular cross-section channel; Circularity; Condensation; Convective condensation; Cross-sections; Ethanol; Experimentation; Flow mapping; Flow regimes; Heat exchange; Heat exchangers; Heat transfer; Heat transfer coefficient; Heat transfer coefficients; Pressure drop
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2018.08.077

•Identification by shadowgraph of the wavy-stratified and the wavy-annular regimes.•Development of a flow regime map and comparison with the literature.•Measurement of the local mean internal heat transfer coefficient.•Comparison of the measured heat transfer coefficient with the literature.•Measurement of the total pressure drop. In this work, condensation flows of pure ethanol in a horizontal water-cooled circular cross-section heat exchanger were investigated for a mass velocity ranging between 30 and 100 kg m−2 s−1. The inner channel of condensation has inner and outer diameters of 4 mm and 10 mm, respectively, with a heat exchange length of 1020 mm. An adiabatic section consisted of a transparent circular cross-section channel, of 4 mm inner diameter and of 130 mm visible length, was placed downstream of the condenser in order to visualise the condensation flows by shadowgraph technique. Two main flow regimes were identified: the wavy-stratified regime and the wavy-annular regime. A flow regime map was developed and compared with flow regime maps available in the literature. Besides, the local vapour quality and internal heat transfer coefficient were determined and compared with prediction models of the literature. Finally, the total pressure drop in the condenser was determined.