HEИндивидуална стипендия2023–2025

NI2PhORC · Numerical Investigation of Two-Phase flows for ORC applications

„Хоризонт Европа“ — Действия „Мария Склодовска-Кюри“

Период: 2023-09-01 → 2025-10-31
Финансиране от ЕС: 188 590 €
Участници: 1
Схема: HORIZON-TMA-MSCA-PF-EF

Линиите свързват координатора с партньорите.

Накратко на български

Двуфазните потоци от течност и пара се анализират чрез компютърни модели, например при работата на системи за възстановяване на отпадна топлина. Това помага за по-доброто разбиране на процесите при генериране на електроенергия от топлинни източници под 300°C.

Този кратък обзор е генериран от изкуствен интелект

Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.

Резултати накратко

Numerical Investigation of Two-Phase flows for ORC applications

Compressible two-phase flows play a crucial role in many technical applications, where they can manifest as condensation and evaporation in unsteady flows, liquid accumulation in pipelines, boiling and cavitating flows. A relevant example is found in Organic Rankine cycle (ORC) systems, one of the most promising technologies for waste heat recovery. Unlike conventional Rankine cycles, ORCs use organic fluids, which makes them particularly suited for power generation from thermal sources below 300°C. These fluids may exhibit the so-called wet-to-dry expansion: starting within the two-phase region at sufficiently high pressure, an isentropic expansion can end in the dry-vapor region. This distinctive thermodynamic behavior exhorts the investigation of ORCs operating with two-phase expansion. The overarching goal of the NI2PhORC project is to deliver a computational fluid dynamics (CFD) tool tailored to compressible unsteady non-equilibrium two-phase flows. In CFD, diffuse-interface methods are effective approaches for compressible multiphase flows, able to handle the complexities of evolving material interfaces that separate distinct fluids. At the core lies the Baer-Nunziato (BN) model, which describes compressible two-phase flows in full non-equilibrium, with each phase evolving according to its own pressure, velocity, temperature, and Gibbs free energy. Various BN-type models have been proposed, incorporating different transfer terms for mass, momentum, and heat exchange between phases. Relaxation terms may also be added to model how the mechanical equilibrium is reached at the interfaces and to include heat and mass transfer. With suitable closures, BN-type models have proven effective in simulating a wide range of multiphase regimes, from dispersed to resolved-interface flows. Moreover, they are particularly suited for fluids described by different equations of state (EOSs), since each phase is treated as a separate continuum with its own thermodynamic model. This capability is essential when working near the saturation curve, where organic fluids often deviate strongly from ideal-gas behavior. Nevertheless, open questions remain regarding the proper definition of finite relaxation parameters in BN-type models. While instantaneous mass transfer has been shown to be inadequate to match experimental data, an unambiguous formulation for finite relaxation times is still lacking. The NI2PhORC project will aim to extend modeling capabilities for compressible two-phase flows by developing a CFD tool with relaxation parameters that can be tuned based on physical insight or application-specific needs.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз

Цел на проекта

With this proposal I aim to develop an accurate and robust numerical tool for the simulation of compressible two-phase flows for Organic Rankine Cycle (ORC) applications. Recent studies have shown that the power output of ORC systems may be increased up to 30% by implementing a wet-to-dry turbine expansion, which starts in the two-phase regime and ends in the dry vapor. Advanced numerical tools are required to confirm these predictions, and to investigate more accurately these flows. To ensure an adequate level of reliability, I propose to develop a numerical tool based on the non-equilibrium Baer and Nunziato (BN)-type model. The suggested model naturally takes into account non-instantaneous mass and heat transfer. By using an adaptive strategy based on non-standard criteria to predict the local flow topology, the model will also be able to deal with the different flow topologies that occur in a wet-to-dry expansion. Finally, the effects of the finite relaxation scales will be investigated through a parametric study, and specific empirical indications for two-phase ORC systems will be delivered to the community involved in their optimization and design.The developed simulation software will be released under an open-source policy within the SU2 simulation toolkit, a choice that will help engineers solve transient two-phase fluid dynamics problems. The ensuing availability of an adaptive diffuse interface method will also contribute to answer the need for advanced numerical methods able to effectively deal with the multiscale nature of two-phase flows.The inter-disciplinary character of the NI2PhORC project, which blends techniques of fluid dynamics, applied mathematics, and scientific computing, represents an invaluable opportunity for me to develop a solid and comprehensive scientific background to advance my scientific career within an engineering department.

Оригинален текст от CORDIS (на английски).

Участници

POLITECNICO DI MILANO · MilanoКоординаторИталия