Experimental study on the characteristics of steam direct contact condensation with non-condensable gas in a T-junction minichannel with flowing subcooled water

• Published in: Applied thermal engineering Vol. 257; p. 124345
• Main Authors: Li, Shuqian, Qi, Xiaoni, Qu, Xiaohang, Zhou, Pengcheng, Su, Chang, Zhang, Chaoqun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2024
• Subjects: Direct contact condensation; Non-condensable gas; Pressure oscillations; Steam plume; T-junction minichannel; Non-condensable gas; Direct contact condensation; Pressure oscillations; T-junction minichannel; Steam plume
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2024.124345

•Three typical condensing flow patterns were identified.•A compound condensation regime was identified which had not been reported before.•The phenomenon of "partial implosion of steam plume surface" was found.•The non-condensable gas significantly affected pressure oscillations. In order to investigate the effect of non-condensable gases (NCGs) content on direct contact condensation (DCC) of steam at the mini-scale, a series of experiments on mixed gas condensation were carried out with steam mass flow rate of 0.2–1.0 g/min, subcooled water mass flow rate of 2–20 g/min, water temperature of 40 °C, and NCGs mass flow rate of 0–0.1935 g/min. The results show that the condensation regimes were significantly affected by the content of non-condensable gas and the mass flow rate of the subcooled water. Three typical condensation regimes were observed under different operating conditions, namely chugging, chugging &bubble flow-slug flow-microbubble flow and slug flow-long bubble flow, the last two of which were newly discovered compound condensation regimes. Furthermore, a three-dimensional steam condensation regime diagram was also created. The instantaneous position of the head of the plume was obtained, which has the characteristics of oscillation and significantly by the content of the NCGs content. In addition, the frequency and amplitude of instantaneous pressure oscillations decrease with the increase of non-condensable gas content.