Details

Autor(en) / Beteiligte

• Li, Yafei
• Deng, Jianqiang

Titel

Numerical investigation on the performance of transcritical CO2 two-phase ejector with a novel non-equilibrium CFD model

Ist Teil von

• Energy (Oxford), 2022-01, Vol.238, p.121995, Article 121995

Ort / Verlag

Oxford: Elsevier Ltd

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Flashing flow in the transcritical CO2 ejector was simulated using a novel non-equilibrium evaporation-cavitation CFD model. The novel model was verified using the experimental results of three ejectors with nozzle diverging angles (NDAs) of 0°, 2.00° and 6.70°. Furthermore, the effects of dimensions of mixing chamber and diffuser on the ejector performance were disclosed. The results suggested that prediction errors of secondary flow mass flow rate using the proposed model were less than 9%, and the maximum error of primary flow mass flow rate was within the range of 15%, which was much smaller than that of −34.55% predicted by homogenous equilibrium model. The results also showed that the mass transfer rates increased with increasing NDAs, and the maximum mass transfer rate of evaporation was approximately 3–13 times that of cavitation as the NDAs increased from 0° to 6.70°, proving evaporation dominates the flashing process in the CO2 ejector. Besides, the results showed that the entrainment ratio increased first and then decreased with increasing the mixing chamber width, mixing chamber length and diffuser angle, and the entrainment ratio was improved by 36.55%. This study is helpful to understand flashing mechanisms inside the CO2 ejector and improve the ejector performance. •A novel non-equilibrium CFD model was built to simulate flashing in CO2 ejector.•The proposed model considered evaporation and cavitation effects simultaneously.•The non-equilibrium CFD model was compared with homogenous equilibrium model.•Expansion characteristics were numerical studied by varying nozzle diverging angles.•Dimensions of mixing chamber width, length and diffuser angle were analyzed.