Non-equilibrium critical flow characteristics of trans-critical carbon dioxide in short tube
A two-fluid model and a homogeneous model for trans-critical carbon dioxide in a short tube were developed.Both inter-phase velocity slip and temperature difference were taken into account in the two-fluid model, but not in the homogeneous model. Experimental results on the mass flow rate were used to verify these two models.The results showed that for the two-fluid model the deviation of 90% model prediction was under ±20%.Furthermore it could give reasonable pressure distribution along the tube length.The homogeneous model could also give reasonable prediction results,and not seriously lower than measured results while disregarding the non-equilibrium characteristics.The non-equilibrium flow characteristics of trans-critical carbon dioxide in the short tube are not obvious which could also be verified by small inter-phase velocity slip and temperature difference.Finally, this phenomenon was given theoretical explanation.