Additive manufacturing (AM) process offers tremendous gains over conventional subtractive manufacturing in heat exchanger design, key issue of thermal engine efficiency. The STREAM project aims at designing novel modeling strategies for the performance prediction of additive-manufactured heat exchangers. The consortium consists in two laboratories CNRS-CORIA and CNRS-LEGI, which have a long experience in high-fidelity multi-physics turbulent flow modeling and TEMISTh, a SME which develops customized solutions for heat exchangers. From the fluid dynamics point of view, AM often introduces important wall roughness, which depends strongly on the manufacturing process itself, and which impacts heat transfer and pressure loss across the device. It is therefore mandatory to design Computational Fluid Dynamics (CFD) models with a sufficient level of accuracy to predict the performances of heat exchangers. RANS (Reynolds-Averaged Navier-Stokes) and LES (Large-Eddy Simulation) are two complementary turbulence modeling approaches that are good candidates for such challenge. In these approaches, wall modeling often relies on statistical analysis, leading to law-of-the-wall models that are widely used in the prediction of internal flows. However, these models need to be extended and validated for wall roughness generated by additive manufacturing. To this aim, STREAM proposes to build a large database of high-fidelity roughness-resolving Large-Eddy Simulations that will be analyzed to derive well-parametrized statistical wall models. An original wall model parametrization will be used that has already been successfully adapted to heat transfers on a turbine blade. The resulting statistical model, usable in both roughness-modeled RANS and LES approaches, will be extensively validated a priori by comparison with the high-fidelity database and a posteriori on classical heat exchanger applications: Fuel-Cooled Oil Cooler, Air-cooled Oil cooler, Surface Air-cooled Oil cooler.

exPerimental And Numerical mulTiscale mulTiphasic Heat ExchangeR Heat exchangers have a fundamental role in aviation engineering. Heat echanger development is ever in progress, to reduce the heat exchanger volume and to enhance the performances. Although the F-gas II regulation does not yet apply to the aeronautical field, actions are being taken by the entire industry to reduce the environmental footprint of air traffic and investigate the use of low GWP refrigerants. Currently, multiphasic heat exchanger headers have mainly been designed and optimized with an empirical approach and an experimental validation. And the multiphasic heat exchanger core is up-to-now designed with experimental-based correlations, all obtained with the high GWP fluids. PANTHER project totally fits in the breakthrough requirements, taking advantage of the new optimization strategy of headers coupled with innovative CFD models of the heat exchanger core. The greatest strength of the PANTHER project is close collaboration of the CFD model development together with the experimental facilities for an optimum validation. PANTHER project will carry out numerical simulations to optimize multiphasic heat exchanger performances: through a 3D CFD porous media model taking into account phase change phenomena and fin structures. For the optimization, topological optimization and adjoint methods will be assessed. To validate the developed CFD models, PANTHER will design, construct, and characterize and two experimental facilities; • The adiabatic experimental set-up will validate the adiabatic multiphasic porous media model • The multiphasic experimental set-up will validate the multiphasic porous media model with heat and mass transfer model, and validate also the optimization chain methodology. The facility will work with an air mass flow range of 0.01 kg/s to 0 0.5 kg/s, an air temperature range of [-10:60°C], refrigerant flow range up to 80 g/s. The chosen fluid for testing is R1234ze.

New Additive manufacTuring Heat ExchaNger for Aeronautic Today’s technologies and processes dedicated to the exchangers manufacturing hamper progress on higher performances (mechanical assies of repetitive and regular unitary components like folded sheet metal and/or tubing mostly welded). Traditional manufacturing entails limit for the customization of the inner structure, which have a direct impact on the thermal behavior of the exchanger core. Design and manufacture a complex core structure accordingly and well adapted to the inner thermal phenomenon seems to be a promising way to increase performances. Accordingly, NATHENA project aims at developing new complex inner structures for heat exchangers. NATHENA project will focus on the design development of a complex compact heat exchanger that best addresses thermal performance, made by additive manufacturing. These new compact air-air heat exchangers developed in NATHENA project will provide an efficient thermal management system dedicated to hybrid propulsion system. Two types of material will be studied regarding heat exchanger use: Aluminium for low temperature range and Inconel for high temperature range. The set objectives (see targets below) will be reached using calculation and multi-physical simulation (thermo-mechanical-fluidic) applied to evolutionary latticed and thin-walled structures combined optionally with fins to form a matrix of complex structures. Predictive models and/or laws will be developed for pressure and temperature drop. Topological and parametric optimization will be carried out in an iterative way towards the most efficient model. Through sample tests and final element method, calculation correlations will be carried out to ensure the relevance and validity of the basic structural choices as well as their combinations. Targets: Delta temperature: 200°C to 400°C Flow: 0.01kg/s to 2kg/s Power: 0.5 to 500kW Reynolds number: 400 to 10000 Pressure drop: 100mBar max Size: up to 500x300x300mm

The DESOLINATION project aims to couple efficiently the low grade wasted heat of two different CSP cycles to an innovative desalination system based on forward osmosis. Indeed, the demonstration in Saudi Arabia already hosts a 100kWe air Bryton cycle that will be coupled with the innovative forward osmosis desalination system developed in DESOLINATION. Moreover, to take into account the future and most efficient cycles, a 1MWe CO2 blends power cycle will be installed on site and demonstrated alongside the existing power plant. More than 2300 hours of testing are planed on site to assess the CSP and desalination technologies and optimise their efficiencies. DESOLINATION will thus provide solutions to be integrated in existing CSP plants across the region as well as an innovative more efficient coupling with a tailored made power cycle for more efficient and cost effective new CSP plants based on CO2 blends. Gathering 10 EU research centres or academic profiles, 6 EU companies with a deep knowledge of the market, and 4 academic partners from the GCC countries, DESOLINATION offers a balanced and high international level consortium, with excellent research capacities and a strong market uptake potential. DESOLINATION indeed aims to have market competitive solutions showing the potential for high wasted-heat-to-freshwater conversion efficiency as well as high CSP power efficiency (>42% at 550°C) leading to an LCOE below 90€/MWh and LCOW below 0.9€/m3 when scaled-up at 100MW scale. The reduction of CO2 emissions per cubic meter of water desalinated would be up to 70% compared to existing desalination systems. Moreover, brine rejection being a key environmental issue, DESOLINATION will also focus on developing solutions to decrease brine rejection by up to 80%. Through the developments of the CSP+D system and its demonstration in a real environment, DESOLINATION will foster the use of solar energy for desalination in the EU, in the GCC countries, and the rest of the world.