Energy efficiency and exergy destruction of supersonic steam ejector based on nonequilibrium condensation model. (5th May 2021)

• Record Type: Journal Article
• Authors: Ding, Hongbing; Zhao, Yafei; Wen, Chuang; Wang, Chao; Sun, Chunqian
• Is Part Of: Applied thermal engineering. Volume 189(2021)
• Publication Date: 2021-05-05
• Subjects: Steam ejector -- Wet steam condensation -- Entropy generation -- Exergy destruction -- Entrainment ratio; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2021.116704
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Mathematical condensation wet steam model with entropy transport for steam ejectors. Dry gas model overestimates entropy generation and exergy destruction by about 16%. Max entropy generation is 1.62 kJ·kg −1 ·K −1 and exergy destruction is 481.7 kJ/kg. Max coefficient of performance reaches 0.5324 with cooling capacity of 3.103 kW. Consider roughness, exergy destruction increases by 13.97% compared to smooth wall. Abstract: With the increasing importance of the environment, energy issues have become the focus of attention. Reducing exergy destruction of the ejector during mixing can increase the entrainment ratio and improve the refrigerating system working efficiency. In this study, a wet steam model integrating a droplet nucleation and growth formulas with four categories of entropy transport equations was established to further analyze thermodynamics properties of ejector. The simulation analyzes of flow pattern, entrainment ratio and coefficient of performance COP, entropy generation and exergy destruction of dry and wet steam flows were carried out under different inlet conditions and roughness. For smooth wall, in the case of primary and secondary temperatures of 120 °C and 14 °C, the COP reaches 0.5324 with the cooling capacity of 3.103 kW. The entropy generation of wet steam flow reaches the maximum value of 1616.37 J·kg −1 ·K −1, and the exergy destruction also reaches the maximum of 481.68 kJ/kg. Considering the analysis of the surface roughness, the maximum of exergy destruction near critical condition point increases by 45.14 kJ/kg for the 500 μm rough wall, and exergy destruction ratio reaches the maximum value of 0.740.