Early-stage oxidation behavior at high temperatures of SiSiC cellular architectures in a porous burner

Early stage oxidation behavior of SiSiC cellular lattices with different cell types was studied at 1400 degrees C in two different environments: a porous burner and an electric furnace with stagnant air. Oxidation and silicon alloy bead formation were observed and identified as the most important factors affecting the integrity of the structures. Low melting temperature silicon-based alloys formed from the material due to presence of impurities. Having lower melting point than the thermal tests temperature, the beads exuded from the microstructure leaving pores in the substrate material and leading to enhanced oxidation on the surface. Moreover, it was observed that different lattice architectures lead to different oxidation behavior on the struts as a result of the changing gas flow paths inside each ceramic architecture. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved

High-Performance SiC–Based Solar Receivers for CSP: Component Manufacturing and Joining

Concentrated solar power (CSP) is an important option as a competitive, secure, and sustainable energy system. At the moment, cost-effective solutions are required for a wider-scale deployment of the CSP technology: in particular, the industrial exploitation of CSP has been so far hindered by limitations in the materials used for the central receiver—a key component in the system. In this context, the H2020 NEXTOWER project is focused on next-generation CSP technologies, particularly on advanced materials for high temperatures (e.g., >900 °C) and extreme applications environments (e.g., corrosive). The research activity described in this paper is focused on two industrial solutions for new SiC ceramic receivers for high thermal gradient continued operations: porous SiC and silicon-infiltrated silicon carbide ceramics (SiSiC). The new receivers should be mechanically tough and highly thermally conductive. This paper presents the activity related to the manufacturing of these components, their joining, and characterization

Innovative Thermal Management Concepts and Material Solutions for Future Space Vehicles

When entering a planetary atmosphere, space vehicles are exposed to extreme thermal loads. To protect the vehicle’s interior, a thermal protection system is required. Future aerospace transportation demands solutions that exceed the performance of current systems and up-to-date material limits. Therefore, new and disruptive solutions must be envisaged to meet those extreme conditions. In the search of new solutions for sharp leading edges of future hypersonic reentry or transport vehicles, the THOR project, composed of eight European organizations (industries, research centers, and universities) and one Japanese Agency (Japan Aerospace Exploration Agency), is actively working on definition, design, implementation, and simulation of new passive and active thermal management solutions and their verification in relevant environments (high-enthalpy facilities). This paper provides an overview of the recent developments on the four concepts that are targeted in the project, applying different physical methodologies: 1) passive cooling using highly conductive carbon-based fibers, 2) passive cooling with intensive internal radiative exchange, 3) active cooling based on convection heat transfer using a ceramic sandwich/thermal protection system with ceramic foams/lattices, and 4) active transpiration cooling of external surfaces. Details on these thermal management concepts, requirements from end users, and test configurations, as well as results from experimental and numerical verification, are given

Generative Artificial Intelligence – “GenAI” – Part 1: Technologies and markets

This contribution was delivered on 23 May 2024 on the occasion of the hybrid 2024 edition of EUI State of the UnionThis panel aims to examine the present state of GenAI technologies and markets. It will emphasize the integration of GenAI tools in different industries and sectors, as well as explore the primary funding and investment sources fueling its advancement. The discussion will also focus on the significance of talent and computational capabilities, along with an analysis of the various stakeholders involved in shaping this technology's value chain. Speakers will evaluate potential concerns related to platform dominance and deliberate on approaches to promote a more equitable ecosystem

Pressure Drop and Convective Heat Transfer in Different SiSiC Structures Fabricated by Indirect Additive Manufacturing

The microstructure of porous materials has a significant effect on their transport properties. Engineered cellular ceramics can be designed to exhibit properties at will, thanks to the advances in additive manufacturing. We investigated the heat and mass transport characteristics of SiSiC lattices produced by three-dimensional (3D) printing and replication, with three different morphologies: rotated cube (RC), Weaire-Phelan (WPh), and tetrakaidecahedron (TK) lattices, and a commercially available ceramic foam. The pressure gradients were measured experimentally for various velocities. The convective heat transfer coefficients were determined through a steady-state experimental technique in combination with numerical analysis. The numerical model was a volume-averaged model based on a local thermal nonequilibrium (LTNE) assumption of the two homogeneous phases. The results showed that for TK and WPh structures, undesirable manufacturing anomalies (specifically window clogging) led to unexpectedly higher pressure drops across the samples and increased thermal dispersion. Compared to the TK and WPh structures the manufactured RC lattice and the random foam had lower heat transfer rates but also lower pressure drops. These lower values for the RC lattice and foam are also a result of their lower specific surface areas

Romagnano Sesia - Borgosesia. Studio tecnologico di industrie litiche da raccolte di superficie nelle colline novaresi. Nuovi dati sul Paleolitico piemontese

Studio tecnologico di industrie litiche provenienti da raccolte di superficie non sistematica effettuate nel territorio delle colline novares

Dynamic modeling, simulation and optimization of the partially-autothermal reforming of biogas in coated monolith channels

A dynamic model is proposed describing a catalyst-coated SiSiC monolithic structure taking as a case study the autothermal reforming of biogas (SCR=3; OCR=0.66) in an adiabatic mode of operation. A single channel 2-D representation is assumed including dimensionless mass and energy transport equations solved in gPROMS platform resembling the performance of the whole monolith by breaking down the channel topology into three computational layers, namely the channel, the porous catalytic washcoat, where catalytic reforming and oxidation reactions take place, and the supporting wall. The model is verified using literature kinetics data in comparison with thermodynamic equilibrium analysis in HSC Chemistry software, which hints an optimization scheme for the optimal washcoat thickness to maximize H2 formation. The optimal values are applied to the three-layer model in order to track the dynamic evolution of the dependent variables of temperature and compositions from start-up of the monolith to the introduction of the biogas-O2 feed at the desired temperature to the response of the system to any disturbances being imposed after steady-state is reached. The overall dynamic model can interpret various aspects of the combined combustion and reforming of biogas in catalytic monolithic structures and can be used as an assistance for experiment design and process optimization

Sandwich structured ceramic matrix composites with periodic cellular ceramic cores: an active cooled thermal protection for space vehicles

Ceramic cellular structures and ceramic matrix composites (CMCs), are promising materials for thermal protection systems (TPS) of future space vehicles. This is because of the good thermal properties of their cellular cores coupled with the matchless thermo-mechanical resistance of their CMC skins. A high temperature TPS with active cooling accomplished by flowing a gas into the sandwich’s core is investigated in this work. Three-dimensional thermo fluid dynamics analysis was first performed to evaluate the heat exchange in the ceramic sandwich under a Earth re-entry condition. The simulations, aiming at optimizing the TPS configuration, analysed several cellular ceramics structures by varying inlet and outlet positions, the coolant fluid and mass flows. A hexagonal cell was chosen as basic element of the porous ceramic. Sandwich structure components were produced and assembled by joining. Finally a prototypic leading edge was produced and tested in plasma wind tunnel in a standard re-entry condition. Cooling was performed with different gases and mass flows. Results are reported and discussed.The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement N° 312807