Thermal Characterization

Ce travail de thèse porte sur la modélisation et la caractérisation des transferts de chaleur et de masse dans les parois multicouches des bâtiments à ossature bois. Un code instationnaire permettant de simuler les transferts de chaleur et de masse dans une lame d'air en géométrie bidimensionnelle, qui est un élément de la paroi multicouches, a été développé et validé. Les validations numériques en régimes transitoire et stationnaire ont porté sur la totalité des modes de transfert (conduction, écoulement en convection naturelle et forcée, rayonnement entre surfaces, transfert massique et condensation surfacique). Ensuite, ce code intégrant la présence d'une lame d'air dans la paroi a été couplé au code Transpore développé au LERFOB. Ce dernier traite rigoureusement les transferts dans les matériaux solides hygroscopiques. Pour la validation expérimentale du code complet couplé, une cellule expérimentale a été construite et instrumentée pour étudier le comportement hygro...

This study investigates the effect of fiber content and coupling agent concentration on the mechanical and thermal behavior of a polypropylene-based composite. The materials were fabricated via hot compression
molding using pellets composed of polypropylene (PP) modified with maleic anhydride-grafted polypropylene (MAPP) and reinforced with short bamboo fibers derived from Guadua angustifolia Kunth (GAK). The
fibers were previously extracted through the steam explosion technique. The research was carried out in two stages: first, the composite materials were produced; second, their mechanical and thermal properties were
comprehensively characterized. The incorporation of GAK fibers and MAPP significantly altered the mechanical performance of the PP matrix, yielding stiffer composites with improved flexural strength and impact resistance. The optimal formulation, containing 50 wt% GAK fibers and 4 wt% MAPP, resulted in a 322% increase in elastic modulus (2.9 GPa) compared to neat polypropylene (0.7 GPa). Both variables, fiber content and compatibilizer concentration, were found to exert a substantial influence on the mechanical behavior of the resulting composites.

The biodegradability, morphology, and mechanical properties of composite materials consisting of acrylic acid-grafted poly(hydroxyalkanoate) (PHA-g-AA) and rice husk (RH) were evaluated. Composites containing PHA-g-AA (PHA-g-AA/RH) exhibited noticeably superior mechanical properties compared with those of PHA/RH because of greater compatibility with RH. The dispersion of RH in the PHA-g-AA matrix was homogeneous because of ester formation and the consequent creation of branched and crosslinked macromolecules, between the carboxyl groups of PHAg-AA and hydroxyl groups in RH. The water resistance of PHA-g-AA/RH was higher than that of PHA/RH, although the weight loss of composites buried in soil compost indicated that both were biodegradable, especially at high levels of RH substitution. After 60 days, the weight loss of the PHA-g-AA/ RH (40 wt%) composite was greater than 90 %. PHA/RH exhibited a weight loss of approximately 4-8 wt% more than PHA-g-AA/RH. The PHA/RH and PHA-g-AA/RH composites were more biodegradable than pure PHA, which implies a strong connection between RH content and biodegradability.

La présente étude numérique traite du transfert thermique en mode de convection forcée, mixte et naturelle, au sein d'une cavité, à parois mobiles, contenant un fluide non newtonien obéissant au modèle rhéologique de Bingham. L'étude concerne l'influence du rapport de forme, du nombre de Bingham ainsi que celle du nombre de Richardson sur le comportement hydrodynamique et thermique de l'écoulement du fluide considéré dans cet espace confiné.

RESUME. L'article présente la modélisation thermique et la simulation sur lesquels s'appuiera la conception d'une cellule test. La cellule a pour objectif la caractérisation des propriétés thermo-physiques des composants d'enveloppe transparents et opaques dans des conditions climatiques réelles, et d'étudier l'impact de différentes configurations de climatisation sur le confort thermique intérieur et la qualité de l'air intérieur. Le retard de réponse de la mesure calorimétrique est un aspect particulièrement critique afin de garantir une bonne qualité de mesure dans des conditions climatiques qui varient rapidement. Pour cette raison, le comportement thermique de la cellule test a été décrit à travers un modèle à paramètres localisés, pour simuler toute une gamme de conditions de fonctionnement. Les résultats sont utilisés pour évaluer l'inertie thermique de différentes solutions, affiner les choix de conception et les stratégies de contrôle les plus prometteuses. L'article présente le modèle thermique développé pour comparer la cellule test à une installation traditionnelle en termes de précision calorimétrique dans des conditions externes transitoires. MOTS-CLÉS: cellules test, méthode de mesure, facteur de transmission totale de l'énergie solaire (ou facteur solaire, g) ABSTRACT. The article presents the thermal modelling and simulation work that will constitute the basis for the design of an outdoor test cell. The facility aims at characterizing the thermo-physical properties of transparent and opaque envelope components under real weather conditions, and to study the impact of different air-conditioning configurations on the indoor thermal comfort and indoor air quality. The response delay of the calorimetric measure is particularly critical when trying to achieve a good quality of measurement in rapidly-varying weather conditions. For this reason, the thermal behaviour of the test cell has been described, by means of a lumped parameter model, to simulate a range of operating conditions. The results are used to evaluate the thermal inertia of different solutions, refine the design choices and the most promising control strategies. The article presents the thermal models used to compare the test cell to a traditional installation in terms of calorimetric accuracy under transient external conditions. KEYWORDS : test cell, measurement method, total solar energy transmittance (or solar factor, g) brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Archivio istituzionale della ricerca -Politecnico di Milano

L’objectif de ce travail est de simuler les transferts bidimensionnels de chaleur et de masse au cours du séchage d’un milieu poreux non saturé et indéformable exposé à un écoulement convectif forcé laminaire d’air humide dans un canal horizontal. Le modèle utilisé tient compte d'une part des approximations des couches limites dynamique, thermique et massique et d'autre part de la variabilité des coefficients des transferts thermique et massique. Les résultats obtenus, nous ont permis d’évaluer l’influence de la hauteur du canal sur le processus de séchage et sur les comportements spatio-temporels de la température, de la saturation en eau et de la pression du mélange gazeux.

National audienceThis study focuses on 2D modeling of a process of air compression in a liquid piston. In order to study this flow numerically, the choice was made to use the VOF (Volume of Fluid) method which is adapted to this type of flow. The flow regime switchs from laminar to transient, so the LES (Large Eddy Simulation) method was chosen for turbulence modeling. We tried to get closer to the experimental results and to better illustrate the different physical phenomena present during the compression using different approaches.Cette étude porte sur la modélisation 2D d'un processus de compression d'air dans un piston liquide. Afin d'étudier numériquement cet écoulement, le choix a porté sur l'utilisation de la méthode VOF (Volume of Fluid) qui est adaptée à ce type d'écoulement. Le régime de l'écoulement varie au cours du processus de compression passant de laminaire à transitoire puis turbulent, ainsi la méthode LES (Large Eddy Simulation) a été choisi...

Compte tenu des importants transferts de chaleur qu'ils induisent, les procédés de refroidissement par des écoulements diphasiques sont utilisés dans de nombreuses applications industrielles. Le refroidissement des pistons moteur, faisant intervenir un écoulement diphasique incompressible (huile/air), en est une application intéressante. Nous nous proposons de modéliser ce procédé de refroidissement à l'aide du modèle 1-Fluide diphasique couplé à l'équation de la chaleur. Les échanges de chaleur dans le cas d'écoulements uniformes parallèles et de jets impactants sur une surface chauffée seront abordés dans cette étude. Nos résultats numériques seront comparés à des solutions semi-analytiques disponibles dans la littérature. Une étude expérimentale concernant un jet liquide cylindrique impactant sur une surface chauffée semi-hémisphérique a également été menée et servira de référence pour nos résultats numériques.

Que ce soit dans une problematique de sechage, ou de diagnostic des structures, la caracterisation de l’eau dans le bois est un sujet qui preoccupe les chercheurs depuis des decennies, car cette derniere a une forte influence sur les caracteristiques mecaniques de ce materiau. Ainsi, de nombreuses etudes ont menees a la creation de modeles de transfert hygrothermique ont ete concu, prenant en compte les transferts de vapeur et d’eau liee et/ou libre. [WUFI, TRANSPORE, …] Toutefois le nombre important des parametres de diffusions dependants de la temperature et de la teneur en eau conduit souvent a simplifier ces dependances.

This work provides a preliminary experimental investigation with a laboratory setup for proposing a novel enhanced thermometric method, for the thermal characterization of building walls, utilizing a non-contact approach based on infrared thermometry. The goal is a non-invasive application in building diagnostics, particularly in heritage and architecturally sensitive contexts.
This study aims to investigate two issues: (i) testing a procedure to automatically process data for determining suitable heat transfer coefficients when calculating heat fluxes when the thermometric method is applied; (ii) understanding the role of infrared thermometers in replacing contact temperature sensors in a proposed enhanced version of the thermometric method for heat flux calculation. Heat fluxes acquired through a commonly used sensor were compared with those computed through the proposed method based on convective and radiative heat transfer assessments.
The findings validate the viability of the indirect procedure for calculating heat flux. However, discrepancies in surface temperature measurements were observed between contact and infrared sensors, with differences below 0.5 ◦C. This suggests that infrared thermometers may require careful consideration as they can underestimate surface temperatures, potentially
necessitating corrections to obtain heat flux values comparable to those from conventional heat flux sensors.

qui régissent la conduction d’énergie au sein des parois de la cellule, la convection naturelle à l’intérieur du local ainsi que les échanges de chaleur par rayonnement entre les surfaces internes du bâtiment en question sont discrétisées par la méthode des différences finies, basée sur l’approche des volumes de contrôles et sont résolues en utilisant l’algorithme SIMPLEC (Semi-Implicit-Method for PressureLinked Equations Corrected) développé par Patankar et Spalding. Les effets du nombre de rayonnement et le rapport de températures sur le transfert de chaleur par convection et sur le flux de chaleur global traversant le bâtiment font l'objet de cette étude.

Nous étudions numériquement l'écoulement de convection naturelle dans un canal vertical soumis à une stratification. Des conditions aux limites périodiques sont imposées dans la direction verticale. L'influence de la stratification et du nombre du Rayleigh est examinée. Un modèle peut être utilisé pour le régime faiblement nonlinéaire autour de la première bifurcation. Au-delà d'un nombre de Rayleigh plus élevé on observe l'apparition d'ondes solitaires.

Cette étude vise à analyser l'influence de la forme géométrique sur le transfert de chaleur dans un matériau isolant, en l'occurrence le plâtre. À l’aide de simulations numériques réalisées sous MATLAB, trois géométries différentes ont été étudiées : le bloc rectangulaire, le cylindre et la sphère. Chaque configuration a été soumise à des conditions thermiques stationnaires afin d'évaluer la distribution de température et la performance thermique en fonction de la géométrie. Les résultats montrent que la forme géométrique joue un rôle significatif dans le comportement thermique du plâtre, influençant la répartition de la température ainsi que le flux thermique. Cette étude met en évidence l'importance du choix de la géométrie dans la conception de systèmes d'isolation thermique.

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Distributed under a Creative Commons Attribution-NonCommercial 4.0 International License Estimation des transferts thermiques dans un procédé de dépôt assisté par plasma (PACVD) : influence du milieu plasma

L’objectif de ce travail est de simuler les transferts bidimensionnels de chaleur et de masse au cours du séchage d’un milieu poreux non saturé et indéformable exposé à un écoulement convectif forcé laminaire d’air humide dans un canal horizontal. Le modèle utilisé tient compte d'une part des approximations des couches limites dynamique, thermique et massique et d'autre part de la variabilité des coefficients des transferts thermique et massique. Les résultats obtenus, nous ont permis d’évaluer l’influence de la hauteur du canal sur le processus de séchage et sur les comportements spatio-temporels de la température, de la saturation en eau et de la pression du mélange gazeux.

Suberin samples, obtained by alkaline methanolysis from cork (Quercus suber L.), were submitted to various physical characterizations; DSC, TGA, optical microscopy, density and rheological properties. A substantial proportion of these oligomers possessed a microcrystalline character with a melting range between 0 and 50°C. The amorphous part was liquid at room temperature and did not display a detectable glass transition upon cooling because of its wide molecular weight distribution. The viscous behaviour of suberin at room temperature was both plastic and thixotropic because of the structuring role of the microcrystals.

Single walled carbon nanotubes (SWNTs) were incorporated in polymer nanocomposites based on poly(3octylthiophene) (P3OT), thermoplastic polyurethane (TPU) or a blend of them. Thermogravimetry demonstrated the success of the purification procedure employed in the chemical treatment of SWNTs prior to composite preparation. Stable dispersions of SWNTs in chloroform were obtained by non-covalent interactions with the dissolved polymers. Composites exhibited glass transitions, melting temperatures and heat of fusion which changed in relation to pure polymers. This behavior is discussed as associated to interactions between nanotubes and polymers. The conductivity at room temperature of the blend (TPU-P3OT) with SWNT is higher than the P3OT/SWNT composite.

The present study investigates the synergistic effects of halloysite clay nanotubes (HNTs) and eggshell powder (ESP) derived from bio-waste on the thermomechanical properties of composites consisting of natural abacá fiber (AF) and polypropylene (PP). First, nine composite sheets of AF/PP incorporating varying loadings of HNTs and ESP (0-6 wt%) were fabricated. The effects of HNTs and ESP on the fracture surfaces of the AF/PP composite using field emission scanning electron microscopy (FESEM) were examined. Subsequently, various experimental tests on the composite samples, including bending tests, differential scanning calorimetry (DSC), and cone calorimeter tests (CCT) were conducted. The results of the bending tests revealed a considerable improvement in the flexural properties of the samples containing HNTs. Specifically, the maximum flexural stress and flexural modulus of the composite containing 6 wt% HNT (H6E0) exhibited approximately 40% and 84% higher values, respectively, compared to the pure AF/PP composite (H0E0). Conversely, the incorporation of ESP had a detrimental effect on the flexural properties of the composites. Additionally, DSC analysis showed an improvement in the thermal behavior of the composite samples upon adding both ESP and HNTs. The results also revealed that while both HNT and ESP had positive effects on the melting temperature (Tm), the impact of ESP was more pronounced. Specifically, the experimental data indicated improvements of 0.9% and 2% in the Tm for the 6 wt% ESP-loaded composite (H0E6) and 6 wt% HNT/6 wt% ESP-loaded composite (H6E6) samples, respectively. Moreover, the CCT results showed that the composite sample containing 3 wt% HNT and 6 wt% ESP exhibited superior flame-retardant performance, indicating significantly improved flammability behavior of the AF/PP composites.

infrastructures, construction industry, home and office furniture, etc.). Of the pool of commercially available NFs, the AF has been the choice for synthesizing countless NF composites. Extracted from the Musa textilis (i.e., a plant) (Ochi 2006), AF is dominantly produced in the Philippines wherein 84% of total demand for the abaca around the globe is being supplied at an annual average rate of 68,000 t/year (Barba et al. 2020). In terms of appearance, the abaca plant looks like a banana tree in that it has a root system in the middle from which 12-30 stems are originated. Growing to up to 8 m, the stems (i.e., stalks) are peeled to obtain AF. With lengths in the range of 1.5-3.5 m, the AFs exhibit various colors ranging from white to red and then to brown and black or purple (Vijayalakshmi et al. 2014). Being a highly strong commercially available NF, AFs have found diverse applications. The ever-increasing industrial application of AF as a sustainable source of fiber is associated with its

The hybrid PVT system proved to be much more energy efficient with improved electrical efficiency due to the cooling of PV cells and gained thermal energy due to heat absorbed from the heated PV cells. The glazed, unglazed, and different thermal absorber configurations of PVT modules are investigated by different research teams. In this work, the influence of the thermal insulating back sheet on the operational temperatures of PVT modules theoretically and experimentally is investigated. The PVT hybrid modules with the thermal insulating back sheet and without the thermal insulating back sheet are considered. The comparative analysis of operational temperatures of PVT modules and general PV modules is conducted. It is shown that at low ambient temperatures (below some "critical" value) the temperature of the PVT module can be higher than the temperature of the general PV module ("reverse" process). It is also shown that the PVT hybrid module without a thermal insulating back sheet can be used in a broader range of ambient temperatures than the PVT module with the thermal insulating back sheet. The results of this work can be used by scientists and engineers for optimal design and application of PVT hybrid modules and systems.

In situ tests are suitable to confirm the real thermal performance of building
components, and several significant on-site measurement techniques have been studied in literature. However, among them the Thermometric (THM) method has been poorly examined by the scientific community, thus having opportunities for improvement, being a quite a new and non-standardized technique. The theory behind this technique is the Newton’s law of cooling
and the main issue is associated to the heat transfer coefficient for which there is no agreement about the value to use. Here, a simple experimental apparatus characterized by a vertical heated sample, suitably thermally insulated was realized. Sensors were installed and direct heat flux
measurements through a heat flux plate were performed and compared with (i) the heat flows obtained through the THM method (test conducted using the internal heat transfer coefficient recommended by the ISO 6946) and (ii) the heat fluxes obtained through the proposal of an enhanced THM method based on dimensionless groups analysis, thus requiring data processing based on convective and radiative components.

The aim of present study is to investigate different methodologies to retrofit photovoltaic modules (PV), in order to ensure a good cooling effect by adding a thermal plate in the back side of the PV panel to collect heat, thus obtaining a thermal photovoltaic module (PVT). The most promising perspective of this technology is to couple it with a heat pump, in order to obtain a photovoltaic thermal solar-assisted heat pump (PVT-SAHP) system. This work proposes an investigation of three different solutions to retrofit commercial PV panels. A thermography analyses has been performed in order to verify the cooling effect on the PV module. Results show that retrofitting of existing photovoltaic panels represents an interesting approach in order to employ very simple solutions to increase the overall efficiency of PV system, especially by coupling it with a heat pump. Finally, in order to study the effective potential of this technology, three different system configurations have been compared in terms of primary energy efficiency, namely a photovoltaic solar assisted heat pump (PVT-SAHP), a solar assisted heat pump (PCEA) and an air-to-water heat pump with a separate set of photovoltaic panels.

Wildfire statistics report an increasing number of deaths, damages, and force society to face exceptional repair costs also due to secondary effects such as landslides, soils erosion and water quality problems. Literature agrees that the extent of the thermal disturbance of the soil due to wildfire is strongly dependent on fire intensity, on its duration and recurrence, as well as on fuel load, and soil properties. The unpredictability of these phenomena is one of the main challenges for scientists trying to study their characteristics. Degradation of the biological, chemical, and physical properties of forest soils due to the wildfires can reduce their capacity to function fully, with such effects either temporary or permanent. Direct measurements of the effects of these phenomena are difficult to be collected in the field, especially when the area affected by fires is a wilderness. In this study, controlled fires reproducing real conditions of wildfire affecting the Susa Valley (NW Italy) in 2017, which induced intense erosion and debris flows, have been monitored both above and below the ground surface. Moreover, numerical simulations based on real data increased the know-how to reproduce real changes on the underground. The small-scale fire simulations have allowed to verify how the depth affected by significant increases in temperatures is truly pellicular. Field tests show that at −2 cm depth temperature never exceed 70°C, meaning that it usually does not affect soil components or properties. The results of the study suggest that temperature variations in the subsoil are very localized and limited. If confirmed by further studies, the processes inferred to produce large ground effects on slopes after wildfires should be reconsidered .

In this paper, Silex Microsystems, the world's largest Pure-Play MEMS foundry, together with partners TNO and VTT, present our recent advancements in RF through silicon Vias (TSV) for 3D integrated passive devices (IPD) applications, achieved in conjunction with the European consortium EPAMO. A novel open TSV fabrication process on 200 mm diameter 305 µm thick High Resistivity wafers has been used to demonstrated High Aspect Ratio Through Silicon Vias (HAR TSV), focusing on tight pitch, resulting in 36 TSV/mm2 Via density. 305 µm wafer thickness enables the fabrication of rigid interposers, an advancement in the commercialization of 3D packaging technology. The fabrication includes double sided deep reactive ion etching (DRIE), developments and evaluation on various conformal high aspect ratio (HAR) plating seedlayer processes, and void-free TSV Cu plating of open rigid TSV structures and bonding to glass wafers for characterization. The electrical characterization of the fabricated devices was performed by VTT with excellent measured RF properties: in specific, low RF losses as well as low DC resistances of less than 20 mOhm/TSV. Several different coplanar waveguide (CPW) test vehicles and other RF TSV test structures together with Daisy Chain and parasitic Capacitance test structures were designed, fabricated and evaluated. The loss of a single coplanar TSV transition is less than 0.04 dB @ 5 GHz, which is considered to be very small. The developed TSV technology was also employed to fabricate 3D toroidal inductors. These inductors were characterized by TNO showing high Q-factor (>30) and selfresonance frequency (> 6 GHz) for 3D inductors in the range of 1-15 nH. 1 and 2 port inductor temperature characteristics over temperature interval from room temperature to 111°C are reported. A fabrication integration scheme for fully integrated RF-IPD with 3D TSV based inductors and high ohmic polysilicon (p-Si) resistors and piezoelectric (PZT) metalinsulator-metal (MIM) capacitors are discussed. Outlook for improvements using integrated high frequency magnetic flux materials and commercialization aspects are described.

This work aims to use experimental data from thermal characterization and adsorption/desorption isotherms of two tropicals woods species (Ayous and Tali) to propose an empirical model of thermal conductivity as a function of air relative humidity. A static gravimetric method was used to determine the adsorption isotherms of Tali and Ayous at 30 °C, and 40 °C. The GAB, Henderson and Nelson models were used to predict the isotherms. Exponential models of thermal conductivity and volumetric heat capacity with air relative humidity were proposed. The influence of hysteresis phenomenum was studied on these properties. The reliability of the developed empirical correlation between thermal properties and air relative humidity was evaluated by comparing the experimental and predicted curves. The relative errors were less than 8% for both Ayous and Tali. The correlation coefficients obtained were greater than 99% for both species in adsorption and desorption. There was also an increase in the equilibrium water content of both species with the increase in water activity at constant temperature. The correlation coefficients between GAB model and sorption experimental data were lower than 99% when Ayous was subjected to a temperature of 40 °C in adsorption and Tali to a temperature of 40 °C in desorption.

Considering the use of the new molding thermoplastic technique, where viscous filaments can be artistically or technically manipulated to create three-dimensional pieces using an extruder, this paper discusses the optimal PP/wood fiber filament preparation conditions especially the thermal degradation. Not only is it essential to know the best processing conditions of the composites but also gain durability and/or advantageous color change when the final products made with viscous filaments are subjected to thermal treatments. Very few papers have been published on polypropylene-pine wood filament composites and the thermal degradation of such filaments. This paper presents the preparation and characterization of filament composites using 5, 10, and 20wt.% pine sawdust with a compatibilizer obtained by hot molding through the use of an extruder, and discusses the effect of both drying time and temperature on the prepared filament composites to understand thermal degradation when subjected to 60°C and/or 120°C. Prepared filament composites are characterized for physical (density, water absorption, and crystallinity), thermal and tensile properties besides their morphology along with fractography. X-ray diffraction results confirmed the data obtained in thermal studies indicating that increased fiber content decreased both the crystallinity and the thermal resistance while decreasing the melting temperature of the filament composites. Fractographic studies revealed low adhesion between the sawdust and the matrix, evidenced by the presence of loose and some unattached sawdust particles in some composites, thus, supporting the observed low strength in these composites, besides the influence of drying time and temperature on the mechanical properties of the composites.

Ce travail a été réalisé au sein du Laboratoire d'Energétique et de Mécanique Théorique et Appliquée (LEMTA) dirigé par Monsieur Fabrice LEMOINE. Je tiens tout d'abord à remercier très chaleureusement mes encadrants, Messieurs Gérard JEANDEL (directeur de thèse) et David LACROIX (co-directeur de thèse), pour m'avoir permis de réaliser cette thèse. Vous m'avez donné la chance de travailler avec une grande autonomie sur un sujet très intéressant, riche et varié. Grâce à vous, je me suis épanoui professionnellement et intellectuellement. Je remercie également tous les membres de mon jury pour leur disponibilité et leurs conseils sur mes travaux de recherche. Je remercie Monika WOLOSZYN et Rafiq BE-LARBI d'avoir accepté d'être les rapporteurs de ce travail. Toute ma gratitude à Patrick PERRE qui a bien voulu présider le jury de ma soutenance de thèse. Toute ma reconnaissance envers Monsieur Denis MAILLET qui m'a donné l'occasion d'enseigner parallèlement à mes travaux de recherche. Un grand merci à tous mes collègues de l'équipe transfert radiatif du LEMTA avec qui j'ai passé d'agréables moments, inoubliables, dans une excellente ambiance. Je remercie d'abord les permanents : Pascal BOULET, Gilles PARENT, Sébastien FUMERON et Bernard MONOD. Ensuite, je salue tous les doctorants de l'équipe et de ma promotion : Lionel TROVALET, Jérôme MULLER et Julien TISSOT. Vous avez fait preuve d'attention et d'entraide pendant les moments de forte concentration à la recherche de " vietnamiens " dans les codes. Vous savez de quoi je parle ! Enfin, je souhaite un très bon courage aux nouveaux et actuels doctorants de l'équipe : Jonathan GERARDIN, Simon DAP, Benjamin LECORRE et Valentin JEAN. Ensuite mes remerciements vont à Zoubir ACEM, notre leader emblématique et charismatique, l'homme qui sait tout faire. Je n'oublie pas non plus Sullivan LECHENE " le showman " pour les parties de PES " par-ci par-là " et des soirées délirantes au chat noir. Je tiens à remercier également les membres du projet ayant permis le bon déroulement de ce travail :

E-mail: schmidtm@jaist.ac.jp Phononic crystals (PnCs), periodic structures where the period is of similar dimension as the phonon wavelength, promise the opening of phononic band gaps (PnBGs) that could improve thermoelectric conversion efficiency and allow thermal rectification, as shown in Figure 1a [1]. Graphene, the atomic layer of carbon atoms in a hexagonal lattice, has a high Young’s modulus of ~1000 GPa and Debye termperature of ~2800 K. Thus, the wavelength of phonons at a given temperature is greatly increased compared to other materials such as silicon. This reduces the requirements for PnC patterning with PnBGs at room temperature. Recently, we have demonstrated sub-10-nm milling of a 3x3 pore array into suspended graphene by helium ion beam milling, where a tightly focused beam of ions (beam diameter <0.5 nm) interacts with the graphene and carbon atoms are ejected through collisions [2]. Up to 300 nm long PnCs with pitch of 18 nm were demonstrated, as well. However,...

Thermal characterization of IC packages and packaging technologies is becoming a key task in thermal engineering. To support this by measurements we developed a family of thermal test chips that allows a wide range of possible applications. Our chips are based on the same basic cell

Thermal insulators based on ethylene propylene diene terpolymer (EPDM) is an effective class of extreme temperature thermal insulators due to their outstanding heat, mechanical and ablative characteristics. This classed insulator is often reinforced by Kevlar pulp and fumed silica. Ammonium sulfate and antimony trioxide combination have been added as a flame retardant. To improve the elastomer ablative characteristics, multi-walled carbon nanotubes (MWCNTs) were added. We have studied different MWCNT concentrations. In this work, we investigated the effect of the MWCNTs content on the characteristics of the selected insulating formulation based on EPDM. The maximum improvement of tensile strength was 60%. Thermal stability increased by 27% through thermal gravimetric analysis (TGA-DTG), while the ablation resistivity was significantly increased by 60%. The weight loss of the 10 phr MWCNT sample decreased by 40% compared with that of the neat sample. Besides, an increase in ablation ...

This paper describes the design, fabrication, and characterization of a two-metal layer RDL structure at 40 um pitch on thin glass interposers. Such an RDL structure is targeted at 2.5D glass interposer packages to achieve up to 1 TB/s die-to-die bandwidth and off-interposer data rates greater than 400 Gb/s, driven by consumer demand of online services for mobile devices. Advanced packaging architectures including 2.5D and 3D interposers require fine line lithography beyond the capabilities of current organic package substrates. Although silicon interposers fabricated using back-end-of-line processes can achieve these RDL wiring densities, they suffer from high electrical loss and high cost. Organic interposers with high wiring densities have also been demonstrated recently using a single sided thin film process. This paper goes beyond silicon and organic interposers in demonstrating fine pitch RDL on glass interposers fabricated by low cost, double sided, and panel-scalable processes. The high modulus and smooth surface of glass helps to achieve lithographic pitch close to that of silicon. Furthermore, the low loss tangent of glass helps in reducing dielectric losses, thus improving high-speed signal propagation. A semi-additive process flow and projection excimer laser ablation was used to fabricate two-metal layer RDL structures and bare glass RDL layers. A minimum of 3 um lithography and 20 um mico-via pitch was achieved. High-frequency characterization of these RDL structures demonstrated single-ended insertion losses of-0.097 dB/mm at f = 1 GHz and differential insertion losses of-0.05 dB/mm at f = 14 GHz.

This work reports the potential of poly(lactic acid)—PLA composites with different halloysite nanotube (HNTs) loading (3, 6 and 9 wt%) for further uses in advanced applications as HNTs could be used as carriers for active compounds for medicine, packaging and other sectors. This work focuses on the effect of HNTs on mechanical, thermal, thermomechanical and degradation of PLA composites with HNTs. These composites can be manufactured by conventional extrusion-compounding followed by injection molding. The obtained results indicate a slight decrease in tensile and flexural strength as well as in elongation at break, both properties related to material cohesion. On the contrary, the stiffness increases with the HNTs content. The tensile strength and modulus change from 64.6 MPa/2.1 GPa (neat PLA) to 57.7/2.3 GPa MPa for the composite with 9 wt% HNTs. The elongation at break decreases from 6.1% (neat PLA) down to a half for composites with 9 wt% HNTs. Regarding flexural properties, the...

Fuel cells are seen as a promising energy-generating technology for the future. These devices have several advantages such as the variety of fuels to be used and a simplicity in the operating system. There are many types of fuel cells and the most interesting ones are the solid oxide fuel cells (CaCOS), because they have a higher conversion efficiency, reaching 65%. Among the devices of the fuel cell, the anode is the one that maintains contact with the fuel, thus, it must present characteristics such as thermal stability, good compatibility with the electrolyte, electronic conductivity and good catalytic activity. Research is being developed for fuel cell components in order to make this technology commercially viable. For the anode, the researches developed are with materials based on nickel, copper, lanthanum, platinum and cobalt. The researches also show that materials with perovisquita structure present great potential when used as anode. For the present work the study of the perovisquitas of the LaNi (1-x) CrxO3-d system was proposed, and the possibility of use as an anode for fuel cells was proposed. For this, 3 compositions LNC37 (x = 7), LNC55 (x = 5) and LNC73 (x = 3) were studied. The compositions were obtained by the Pechini method, the samples were characterized by X-ray diffraction, infrared spectroscopy, differential thermal analysis, scanning electron microscopy, x-ray dispersive energy spectroscopy, and impedance spectroscopy. The composition LNC73 presented a rhombohedral structure of the R-3c space group, however in the studied sintering temperature values this composition showed the presence of a second phase formed by La2NiO4, not demonstrating a structural stability suitable for use in fuel cell electrodes. Among the studied compositions the compositions LNC37 and LNC55 presented only one phase with orthorhombic structure of the space group Pnma, and they gathered properties that indicate the possibility of being used as anode of solid oxide fuel cells.

The essential features of the traditional FPC collectors are; black metal absorber plate (usually metal), tubes, ducts or passages attached to the back surface of the absorbent plate, insulation material to reduce thermal losses, glasses (one or two) and metal box surrounds all the mentioned components tightly (Duffie & Beckman, 2013). The solar photovoltaic is used to convert the solar radiation into electricity directly. The PV model electrical efficiency depends on the solar cell temperature and its performance is affected by the temperature rise. The hybrid photovoltaic thermal PV/T system is a combination of the thermal and electricity simultaneously. It is a combination of solar thermal and PV systems/components. The PV/T system can be classified based on heat transfer techniques

The essential features of the traditional FPC collectors are; black metal absorber plate (usually metal), tubes, ducts or passages attached to the back surface of the absorbent plate, insulation material to reduce thermal losses, glasses (one or two) and metal box surrounds all the mentioned components tightly (Duffie & Beckman, 2013). The solar photovoltaic is used to convert the solar radiation into electricity directly. The PV model electrical efficiency depends on the solar cell temperature and its performance is affected by the temperature rise. The hybrid photovoltaic thermal PV/T system is a combination of the thermal and electricity simultaneously. It is a combination of solar thermal and PV systems/components. The PV/T system can be classified based on heat transfer techniques

The essential features of the traditional FPC collectors are; black metal absorber plate (usually metal), tubes, ducts or passages attached to the back surface of the absorbent plate, insulation material to reduce thermal losses, glasses (one or two) and metal box surrounds all the mentioned components tightly (Duffie & Beckman, 2013). The solar photovoltaic is used to convert the solar radiation into electricity directly. The PV model electrical efficiency depends on the solar cell temperature and its performance is affected by the temperature rise. The hybrid photovoltaic thermal PV/T system is a combination of the thermal and electricity simultaneously. It is a combination of solar thermal and PV systems/components. The PV/T system can be classified based on heat transfer techniques

The essential features of the traditional FPC collectors are; black metal absorber plate (usually metal), tubes, ducts or passages attached to the back surface of the absorbent plate, insulation material to reduce thermal losses, glasses (one or two) and metal box surrounds all the mentioned components tightly (Duffie & Beckman, 2013). The solar photovoltaic is used to convert the solar radiation into electricity directly. The PV model electrical efficiency depends on the solar cell temperature and its performance is affected by the temperature rise. The hybrid photovoltaic thermal PV/T system is a combination of the thermal and electricity simultaneously. It is a combination of solar thermal and PV systems/components. The PV/T system can be classified based on heat transfer techniques

This paper is a contribution to the valorization of Typha Australis as building material. To do this, the crushed fibers of Typha have been agglomerated using clay as binder. The weight percentage of binder is found to be at least 75% to obtain stable materials. The influence of binder content on mechanical and thermal insulation properties was examined. The mechanical properties were evaluated by using a mechanical press. The measurements of thermal effusivity and thermal conductivity of samples have been performed using the transient hot-plate method. Compression and tensile strengths respectively varies from 0.279 to 0.796 MPa and from 0.340 to 0.969 MPa when the weight percentage of binder range from 77-85%. This values have a strong linear correlation with the weight percentage of binder. The thermal conductivity of dry materials varies from 0.117 to 0.153 W m K. . −1 −1 while the thermal effusivity rises from 228.9 to 300.0 J m s. .°C. −2 −1 − 1 2. The results show that the thermal conductivity and thermal effusivity increases with increasing moisture content of materials.

The objective of this thesis is to master quantitative aspects when using nearfield thermal microscopy by using the scanning thermal microscopy technique (SThM). We start by taking an in-depth look into the work performed previously by other scientist and research organizations. From there, we understand the progress the SThM probes have made through the decades, understand the probe sensitivity to the range of conductivity of the materials under investigation, verify the resistances encountered when the probe comes in contact with the sampl and the applications of SThM.Then we look into the equipment necessary for performing tests to characterize material thermal properties. The SThM we use is based on atomic force microscope (AFM) with a thermal probe attached at the end. The AFM is described in this work along with the probes we have utilized.For the purpose of our work, we are only using thermoresistive probes that play the role of the heater and the thermometer. These probes al...

Two main modelisation techniques are the analytic and systemic methods. After a presentation of each method applied to building simulation, this paper emphases the benefit of systemic modelisation for multizone cases. Using a conceptual description of a building issued of previous method, one particular sub-system appears naturally, i.e. the thermal zones. Then, one of the simulationist's problem, the physical coupling of thermal zones, can simply be solved and in a very modular manner. Building description through data structures, required for thermal design, is easily reached. Then, the detail of our datas' organisation is given in the case of our multiple model software, CODYRUN. At the beginning of this work, our objective was to realize a design tool suitable for professionals and usable by researchers. More precisely, CODYRUN is a multizone software integrating both natural ventilation and moisture transfers. During a simulation, one of its most interesting aspects is ...

Two main modelisation techniques are the analytic and systemic methods. After a presentation of each method applied to building simulation, this paper emphases the benefit of systemic modelisation for multizone cases. Using a conceptual description of a building issued of previous method, one particular subsystem appears naturally, i.e. the thermal zones. Then, one of the simulationist's problem, the physical coupling of thermal zones, can simply be solved and in a very modular manner. Building description through data structures, required for thermal design, is easily reached. Then, the detail of our datas' organisation is given in the case of our multiple model software, CODYRUN.