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Senthil kumar Raman,Heuy Dong Kim 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
The unique characteristics of supercritical carbon dioxide (SCO₂) are reason enough to find its use in various engineering applications. But still usability of SCO₂ is not completely explored due to lack of knowledge about its real gas effects. The present study mainly addresses the real gas effects on supercritical CO₂ flow through a supersonic convergent-divergent nozzle. With series of theoretical equations which are based on one-dimensional gas dynamics theory, computer program has been developed to predict the compressible flow characteristics of supercritical CO₂. With the data obtained from the computer program, properties of supercritical CO₂ near critical point is theoretically analyzed with different EOS. Computational analysis also has been carried out to reasonably predict the SCO₂ flows. The deviation in prediction of properties of SCO₂ by a EOS from other one is addressed. Several types of the equations of state were applied to the compressible Navier-Stokes equations. For effective use of available EOS, an attempt is made by coupling ideal gas EOS and real gas EOS to analyze the real gas effect of SCO₂. These results are compared with the computational results of SCO₂ flow through convergent divergent nozzle with a single real gas EOS. The obtained solutions were used to investigate the generic features of supercritical CO₂ flow, in terms of shock wave location, flow choking, total pressure loss, pressure recovery, etc.
A new equation of state to predict S-CO 2 flow with real gas effects
Senthil Kumar Raman,김희동 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3
The accuracy of the thermodynamic properties prediction from the different Equation of state (EOS) varies upon the range of temperature and pressure. Despite the variety of EOS available, there is no de facto for selecting an EOS for particular computational modeling. The EOS model recently developed by Kumar and Kim (K-K EOS) determines more accurately the thermodynamic properties of CO 2than earlier models. In this present study, K-K EOS is successfully implemented in the computational analysis of compressible supercritical CO 2 flow (S-CO 2 ) in the thermodynamic region near and away from the vapour-liquid critical point. Computational results of SCO 2 flow with the real gas properties predicted with the K-K EOS is compared with Span and Wagner (SW EOS) and ideal EOS.
Numerical Analysis of the High-Speed CO₂ Jets Emanating from Chevron Nozzle
Senthil Kumar Raman,Heuy Dong Kim(김희동) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Mixing characteristics, entrainment strength of the CO₂ jet at gaseous and supercritical phase were computationally analyzed in this present work. Chevron nozzle was applied to activate the shear actions between the primary and secondary streams, by means of longitudinal vortices generated from the chevron. The operation characteristics of the chevron nozzle are compared with a conventional convergent nozzle. A CFD method has been applied to simulate the flow field of the supersonic flows and shock waves. Flow features of S-CO₂ jet flow have been compared both qualitatively and quantitatively with G-CO₂ and air jet. Chevron nozzle is found to influence S-CO₂, G-CO₂ and air jet differentially.