Thermodynamic low-order model for the simulation of two-phase expansion within a TFC unit

Numerical modeling of the two-phase expansion phenomenon may provide valuable tools for the evaluation of the efficiency of a Trilateral Flash Cycle (TFC) unit, as well as in the sizing and design optimization process of two-phase expanders. In the present work, a low-order thermodynamic model for the simulation of two-phase expansion in twin-screw expanders has been developed. The model simulates the phase change in the expansion chamber by discretizing it in a sufficient number of sub chambers. At every sub-chamber, the energy and mass balance equations are solved for both liquid and gas phases, similar to a two-fluid model approach. The modeling procedure applies a lumped parameter approach, which requires the calculation of a set of parameters to provide a closure for the mass and energy balance of the expander under different operating conditions. The necessary set of parameters for the two-phase expansion in twin-screw expanders has been identified based on available experimental data. The values of the parameters have been calculated by solving a properly defined optimization problem. The results from the simulations indicate that the developed model can predict with satisfying accuracy the two-phase expansion along the expansion chamber.     «

Numerical modeling of the two-phase expansion phenomenon may provide valuable tools for the evaluation of the efficiency of a Trilateral Flash Cycle (TFC) unit, as well as in the sizing and design optimization process of two-phase expanders. In the present work, a low-order thermodynamic model for the simulation of two-phase expansion in twin-screw expanders has been developed. The model simulates the phase change in the expansion chamber by discretizing it in a sufficient number of sub chambers...     »