Numerical modelling of a two-phase twin-screw expander for Trilateral Flash Cycle applications

This paper presents numerical investigations of a twin-screw expander for low grade (≤100°C) heat to power conversion applications based on the bottoming Trilateral Flash Cycle. After a thorough description of the modeling procedure, a first set of simulations shows the effect of different inlet qualities of the R245fa working fluid and of the revolution speed on the expander performance. In particular, at 3750 RPM and an inlet absolute pressure of 5 bar, the volumetric and adiabatic efficiencies will increase from 24.8% and 37.6% to 61.2% and 83.1% if the inlet quality in the intake duct of the expander increased from 0 to 0.1. To further assess the effects of inlet quality, inlet pressure and revolution speed on the expander performance, parametric analyses were carried out in the ranges 0-1 inlet quality, 5-10 bar pressure and 1500-6000RPM speed respectively. © 2018 The Author(s).European Union’s Horizon 2020 Research and Innovation Programme under grant agreement no. 680599, (ii) Innovate UK (project no. 61995-431253, (iii) Engineering and Physical Sciences Research Council UK (EPSRC), grant no. EP/P510294/1 and (iv) Research Councils UK (RCUK), grant no. EP/K011820/1