Modelicaによる加熱円管内の超臨界CO₂流れの不安定流動予測

抄録

Recently, incorporating supercritical fluids into the systems is becoming popular when envisioning the next generation thermal systems. Especially, using supercritical CO₂ as working fluid to further improve the efficiency of power generation systems is getting a lot of attention. However, this power generation systems may cause unstable CO₂ flow, because of CO₂ phase transition heated under supercritical pressure. According to Ambrosini, There are two types of unstable flow: Ledinegg Instability and Density wave oscillation Instability. In this paper, to realize safe power generation systems using supercritical CO₂, we conducted a survey of CO₂ flow in a heated tube under supercritical pressure based on Ambrosini’s stability map and one-dimensional analysis by using Modelica language. Thus, we derived heating situations that CO₂ flow can cause Ledinegg Instability and Density wave oscillation Instability due to heating CO₂ in a tube under supercritical pressure. In addition, we plan to conduct tests on actual equipment based on the heating conditions obtained in this analysis.