A model based on a homogeneous formulation of the governing differential equations (Navier-Stokes equations) describing the process of pressure drop in a simplified geometry of an expansion valve is investigated and simulated. Numerical solutions are compared to experimental results. The model is a one dimensional formulation in space and the equations incorporates the change in tubes and orifice diameter as formulated in (S. Madsen et.al., Dynamic Modeling of Phase Crossings in Two-Phase Flow, Communications in Computational Physics 12 (4), 1129-1147). The pressure changes in the flow are accounted for through both friction and acceleration as in a conventional formulation. However, in this analysis the acceleration term is both attributed geometrical effects through the area change and fluid dynamic effects through the expansion of the two-phase flow. The comparison of numerical and experimental data are based on pressure predictions and the deviations between experiments and simulations are found to be in the range of 0 to 10%.
International Journal on Heat and Mass Transfer, 2014, Vol 2, Issue 3