Improving a steam TVR: Insights from variable ejector geometry and CFD simulations

• Two flexible TVR designs were developed using 375 CFD simulations to maintain high efficiency under fluctuating steam conditions. • Nozzle Exit Position (NXP), convergent diffuser length (L1), and primary nozzle throat diameter (d2) were identified as the key performance drivers. • A new non-dimensional parameter, (D5*D5)/(L1*D1), was introduced for design comparison, with an optimal range of 0.50–0.70. • CFD-based fixed-geometry TVR optimization improves performance by 35% over conventional design. • Flexible configurations achieved a maximum PR of 48.5%, representing a 50% improvement over the conventional baseline. Conventional Thermal Vapor Recompression (TVR) systems, while reliable, exhibit operational rigidity and significant performance loss under variable feed pressures and off-design conditions. This study addresses these limitations by developing a flexible steam TVR capable of maintaining high efficiency under fluctuating steam conditions. A systematic approach combining theoretical analysis with 375 Computational Fluid Dynamics (CFD) simulations across seven experimental groups was employed. Initial optimization of a fixed-geometry TVR increased the Performance Ratio (PR) from 32.5% to 43.5%. Two flexible configurations were then investigated: (1) a pressure-adaptive movable primary nozzle and (2) a movable spindle adjusting the primary nozzle throat diameter. These achieved maximum PRs of 46.6% and 48.5%, representing 16% and 50% improvements over the optimized design and conventional baseline, respectively. Both configurations maintained stable performance across varying pressures, mitigating efficiency losses. Analyses identified the Nozzle Exit Position (NXP), convergent diffuser length, and primary nozzle throat diameter as key performance drivers. A new non-dimensional evaluation parameter, (D5*D5)/(L1*D1), with an optimal range of 0.50–0.70, provides a robust metric for design comparison. The pressure-adaptive movable nozzle is recommended as the most practical and effective flexible TVR solution.