Effects of Different CO2 equations of state on Condensation Position in Numerical Investigation

Abstract

Supercritical CO2 power generation system have been gaining interest in the field of thermal power conversion due to its high efficiency and compactness. The low power consumption of the near-critical compressor is the key factor for its high efficiency. However, when CO2 is pressurized from a near-critical state to supercritical state, condensation may occur locally due to the high nonlinear behavior of the flow properties in the compressor. In the numerical simulation of compressor, sharp change of CO2 fluid properties near critical point also brings difficulties in capturing the condensation phenomenon. In order to explore the influence of fluid properties on the condensation phenomenon, this article first discussed the difference among the RK equation of state, the PENG-ROB equation of state, and the CO2 real fluid properties from the NIST REFPROP database. Then a numerical three-dimensional simulation was done using a de Laval nozzle model and the results were used to study the influence of fluid properties calculated from different equations of state in CO2 numerical simulation on the condensation position.