Validation and Application of HEM for Non-ideal Compressible Fluid Dynamic

Abstract

In industrial applications such as the Organic Rankine Cycle (ORC), accurate predictions of the system performance rely on simulations of the flow properties of the working fluid. During operation, fluids may exhibit large property changes and non-ideal gas behavior due to phase changes. Especially in recent years, a large number of applications of supercritical fluids have been developed, and the simulation of fluid flow in trans/supercritical conditions has become important due to the drastic changes in its thermophysical properties near the critical point. As a result, the general analytical equations of state (EOS) such as perfect gas EOS and stiffened-gas EOS cannot accurately model the flow of various fluids in organic cycles. In this work, we used the finite volume method coupled with CoolProp, a fluid thermophysical property library, to consider the properties of the real gas. Homogeneous equilibrium model (HEM) is used to deal with the two-phase flows. Rusanov and SLAU approximate Riemann solver are used for the flux computation. The present solver has been used and assessed on a variety of test-cases, including compressible flow in single phase, two-phase and supercritical shock tubes. The accuracy of the simulation results is satisfactory compared to other numerical and analytical solutions. Simulations of supersonic flow in a converging-diverging nozzle were also carried out, and the results were reasonable compared with the experimental results. The solver can reflect the real gas behavior and can be further used in the future for the development of other fluid applications in industry.