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An original generalised procedure of determination of the transonic trajectory has been proposed. The procedure is much faster than the commonly used Newton Critical Point approach. The approach was applied in modelling of a carbon dioxide transonic two-phase flow through the converging-diverging nozzle by means of the Homogeneous Equilibrium Model and Delayed Equilibrium Model (DEM). The simulations concern flows that were experimentally and theoretically investigated in the literature. DEM was prev ously used only in choked water flow simulations. Its application in CO2 flow modelling and the supersonic trajectory part determination is a novel contribution. The adjusted for CO2 version of the closurelaw was proposed. The investigation revealed that the applied Darcy friction factor determination approach has a significant influence on the results. Moreover, the models are unable of producing physically acceptable solutions until theLockhartMartinelli approach is utilised. It was shown that the Friedel approach might be considered more proper for CO2 flows.

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