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International audience; Cob is an earth construction type widespread in Normandy. In this study, thermal and hygrometric behaviour of cob is studied. Two different mixes currently used for cob constructions are used. Several cob formulations are developed by varying fibre content as well as soil mixes. Results show that a higher fibre content leads to a lower thermal conductivity due to thermal conductivity of wheat straw and cob smaller density. Results about hygrometric properties show that knowing hygrometric properties of each component allow to predict cob hygrometric properties. Knowing hygrometric properties allow to determine cob behaviour variation during the building life.

The new design of passive cooling device for box TV is investigated. Experimental measurements of different architecture of miniature heat pipes including flat porous heat pipe, cylindrical micro-grooved and porous heat pipes are presented. The heat pipes temperatures distributions are measured for different working fluid filling ratios. Once the optimal volume is obtained and fixed, tests are carried out to evaluate the thermal performance of the heat pipes by measuring evaporator, adiabatic and condenser temperatures within various heat fluxes. Results, after being analyzed, discussed and compared, show that the flat porous heat pipe is the most effective for heat dissipation. This heat pipe is integrated in a box TV instead of conventional forced air cooling device. The flat heat pipe cooling performance is explored using deionized water. Results show that the heat pipe passive cooling device well cooled the box TV electronic components compared to fans cooling mode and the CPU operating temperature remains lower than its limit value.

International audience; Performance, lifetime, and cost of hybrid electric vehicles and similar applications requiring peak power are directly affected by battery lifetime, performance, cost, and reliability. Different types of rechargeable energy storage systems exist in the market but none can fulfill all the demands but, rather, are designed for specific applications and uses. The performance of lithium-ion batteries is strongly affected by environmental conditions (e.g., operating temperature) and affecting cycling behavior and side reactions resulting in capacity losses. The aging degradation and reduction of the battery lifetime is subject to nonlinear phenomena influenced by temperature and another operational conditions. This chapter focuses on the degradation mechanisms inside lithium iron phosphate batteries (7 Ah cells) at different storage temperatures (60, 40, 25, 10, 0, and − 10 °C) and state of charge (SoC) levels (100%, 75%, 50%, and 25%). From the experimental results, one can observe that the capacity degradation is considerably higher at higher storage temperatures (e.g., 60 and 40 °C) compared to lower temperatures. The higher-capacity degradation is related to the parasitic reactions that occur at higher temperatures, whereby loss of active material and lithium-ion become determining factors. This observation has been confirmed by the increase of the internal resistance, whereby the main contributor is the growth of the solid electrolyte interface. Furthermore, the experimental results show that higher SoC levels have a negative impact on the battery capacity degradation compared to lower SoC levels (e.g., 25%). From the performed analysis, one can conclude that a lithium-ion battery should be kept in a temperature range lower than 40 °C and 75% SoC during its calendar life for guaranteeing long lifetime of the battery.

International audience; This chapter focuses on the technological status and most common chemistries of lithium ion batteries. According to IEA, in the year 2012, the global stock of plug-in hybrid electric vehicles (PEHVs) and electric vehicles (EVs) amounted to more than 18 0000, representing only 0.02 % of all vehicles. Even though the sales of battery-powered vehicles have more than doubled between 2011 and 2012 from 45 000 to 113 000, the global breakthrough has not taken place and battery companies are having difficult times. In the long term, due to legislation which will in effect reduce vehicle emissions, especially in big cities, clean technologies are expected to prosper. Furthermore, increasing the number of charging stations will convince consumers and officials to choose the electrical alternative. The IEA target for the year 2020 is to increase the number of HEVs and EVs to 20 million which represents 2 % of total vehicle stock. In addition to consumer applications there are markets for lithium ion batteries in industries involved with automated forklifts, boats, harbour vehicles, lifts, backup power and larger energy storages.

International audience; Supercapacitors have an important role to play in the development of electric power applications, mostly in the transport domain. Acceleration and braking of cars or trains generate or require a large amount of power during a few seconds. These conditions are particularly suitable for using supercapacitors, which have a very high‐power density and a long lifetime compared to batteries. In these applications, the energetic performance depends mainly on the design of the supercapacitor modules.In automotive and rail applications, the supercapacitor modules are designed according to customer mission profiles of the vehicle. The design methods must also incorporate the constraints and the operating environment of the system (electrical stress, thermal constraints, vibration, etc.). Thus, supercapacitor modules must also work correctly and always provide the required power to the system during their lifetime. Therefore, it is vital to take into account the aging of these components in the phase of system designing.This chapter is devoted to the sizing of supercapacitor modules, taking into account the different constraints mentioned. Several designing methods are discussed and validated by simulation of some real applications. It is important to model the electrical and thermal behavior and the aging of the supercapacitor modules before the sizing. Temperature accelerates supercapacitor and module aging. A decrease in the capacitance and an increase in the series resistance are observed. Consequently, thermal management is a key issue concerning lifetime and performance of supercapacitor modules. We propose to begin this chapter by presenting the characterization, the electrical and thermal modeling and the aging of supercapacitors and finish by the sizing of supercapacitor modules.

International audience; Due to increasing gas prices and environmental concerns, battery propelled electric vehicles (BEVs) and hybrid electric vehicles (HEVs) have recently drawn more attention. In BEV and HEV configurations, the rechargeable energy storage system (RESS) is a key design issue [1–3]. Thus, the system should be able to have good performances in terms of energy density and power capabilities during acceleration and braking phases. However, the thermal stability, charge capabilities, life cycle and cost can be considered also as essential assessment parameters for RESS systems.Presently batteries are used as energy storage devices in most applications. These batteries should be sized to meet the energy and power requirements of the vehicle. Furthermore, the battery should have good life cycle performances. However, in many BEV applications the required power is the key factor for battery sizing, resulting in an over-dimensioned battery pack [4,5] and less optimal use of energy [4]. These shortcomings could be solved by combination of battery system with supercapacitors [6–8]. In [9], it is documented that such hybridization topologies can result into enhancing the battery performances by increasing its life cycle, rated capacity, reducing the energy losses and limiting the temperature rising inside the battery. Omar et al. concluded that these beneficial properties are due to the averaging of the power provided by the battery system [4,6,9]. However, the implementation of supercapacitors requires a bidirectional DC–DC converter, which is still expensive. Furthermore, such topologies need a well-defined energy flow controller (EFC). Price, volume and low rated voltage (2.5–3 V) hamper the combination of battery with supercapacitors [6,10]. In order to overcome these difficulties, Cooper et al. introduced the Ultra-Battery, which is a combination of lead-acid and supercapacitor in the same cell [11]. The new system encompasses a part asymmetric and part conventional negative plate. The proposed system allows to deliver and to absorb energy at very high current rates. The Ultra-Batteries have been tested successfully in the Honda Insight. However, this technology is still under development. In the last decade, a number of new lithium-ion battery chemistries have been proposed for vehicular applications. In [12–15], it is reported that the most relevant lithium-ion chemistries in vehicle applications are limited to lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt aluminum oxide (NCA), lithium manganese spinel in the positive electrode and lithium titanate oxide (LTO) in the negative electrode. In this chapter, the performance and characteristics of various lithium-ion based batteries and supercapacitor will be evaluated and discussed. The evaluation will be mainly based on the electrical behavior. Then the characteristics of these RESS systems will be investigated based on the electrical and thermal models.

International audience; The present chapter describes an overview of flux trapping with enhancement of the critical current density (Jc) of a melt-growth large domain (RE)Ba2Cu3O7-d, where RE is a light rare earth ions such as Y, Gd or Sm. These high-Tc superconductor bulks have attracted much interest for a variety of magnet applications, since high density and large volume materials potentially provide an intensified magnetic flux trapping, thanks to the optimized distribution of pinning centres. The melt growth process and material processing to introduce well-defined flux pinning properties are overviewed. As a first step, we summarize an effort to achieve a growth of homogeneous large grains with the second phase RE211 in the RE123/Ag matrix. RE-Ba-Cu-O material has a short coherence length and a large anisotropy, and thus any high-angle grain boundary acts as a weak link and seriously reduces the critical current density [1, 2]. In engineering applications, high texture and c-axis-orientated single grains/domains are required. Large-sized, high-performance RE-Ba-Cu-O single grains are now commercially available. The trapped flux density (Btrap) due to flux pinning or associated superconducting currents flowing persistently in a RE-Ba-Cu-O grain is expressed in a simple model, such as:Btrap = Aµ0Jcr,where A is a geometrical constant, µ0 is the permeability of the vacuum and r is the radius of the grain [1]. There are two approaches to enhancing the trapped flux of the grain. One is to enhance the critical current density and the other is to increase the radial dimension of the crystals. Increasing the dimension requires the formation of homogeneous grain growth, and the enhancement of the critical current density is encouraged with the improvement of flux pinning properties.

International audience; Estuaries are submitted to a natural filling caused by the settling of cohesive sediments ( < 63 µm). Those sediments, coming mostly from the sea, are transported in estuaries by the tidal currents during ebb and flood flows. During slack water, fluid velocities vanish and particles are no more suspended by turbulent dispersion. Sediment particles settle towards the bottom, and then deposit on the bed and consolidate. Those particles could be resuspended by erosion when velocities are maximal. Flocculation processes (aggregation), erosion, deposition and compaction are major phenomena that must be considered for an accurate prediction of long term behaviour of estuarine sedimentary dynamics. Several modelling approaches exist. A common way is based on the calculation of diluted particles-water mixture motion with a transport equation for the sediment concentration considered as passive (classical approach). A supplementary model is then used to model the phenomena in the sedimentary bed (i.e. the layer of mud with a high sediment concentration). A second way consists in modelling the behaviour of the particles and the water as two interacting effective fluids from the consolidated rigid bed to the water free surface: this is the two-phase approach.The aim of this chapter is to summarise the main hydrosedimentary processes that take place in estuaries and to present different approaches for their modelling. Section 2 is dedicated to the description of the physical processes involved in estuaries. Section 3 presents the classical (single phase) approach focussing on different ways to model the bed evolutions; the rheological and erosion properties of mud are discussed. Section 4 deals with the two-phase model for sediment transport. Several applications are presented. Finally, the shortcomings of each modelling strategy are discussed and the perspectives are given in section 5.

International audience; The large number of automobiles in use around the world has caused and continues to cause serious problems of environment and human life. Air pollution, global warming, and the rapid depletion of the earth’s petroleum resources are now serious problems. Electric Vehicles (EVs), Hybrid Electric Vehicles (HEVs) and Fuel Cell Electric Vehicles (FCEVs) have been typically proposed to replace conventional vehicles in the near future. Most electric and hybrid electric configurations use two energy storage devices, one with high energy storage capability, called the “main energy system” (MES), and the other with high power capability and reversibility, called the “rechargeable energy storage system” (RESS). MES provides extended driving range, and RESS provides good acceleration and regenerative braking. Energy storage or supply devices vary their output voltage with load or state of charge and the high voltage of the DC-link create major challenges for vehicle designers when integrating energy storage / supply devices with a traction drive. DC-DC converters can be used to interface the elements in the electric power train by boosting or chopping the voltage levels. Due to the automotive constraints, the power converter structure has to be reliable, lightweight, small volume, with high efficiency, low electromagnetic interference and low current/voltage ripple. Thus, in this chapter, a comparative study on three DC/DC converters topologies (Conventional step-up dc-dc converter, interleaved 4-channels step-up dc-dc converter with independent inductors and Full-Bridge step-up dc-dc converter) is carried out. The modeling and the control of each topology are presented. Simulations of 30KW DC/DC converter are carried out for each topology. This study takes into account the weight, volume, current and voltage ripples, Electromagnetic Interference (EMI) and the efficiency of each converter topology.

Hafenanlagen werden oft in Gebieten errichtet,wo die Wassertiefen gering sind, insbesondere inÄstuaren. Es ist dann notwendig, Ausbaggerungsarbeitendurchzuführen, um Schiffen die Zufahrtzu ermöglichen. Das ausgebaggerte Sedimentwird in einer vorher definierten Deponierungszonefreigesetzt. Wegen der Konzentration derSedimentwolke, die sich während der Freisetzungbildet (zu Beginn mehr als 350g/l) entsteht einEinfluss auf die Umwelt. Die chemische Zusammensetzungdes Wassers wird direkt beeinflusst.Nach der Freisetzung schlagen sich die Sedimenteunter einer sehr hoch konzentrierten Wolkenieder. Auf diesen Schritt des Niederschlags folgtein Einfluss auf die Sohle durch Bildung einesSuspensionsstroms.Der Zweck dieses Beitrags ist das Studium diesesPhänomens mittels numerischer Simulationenunter Verwendung eines Zwei-Phasen-Modellsfür den Sedimenttransport (Barbry et al., 2000 ;Chauchat et al., 2008 ; Nguyen et al., 2009). Esbasiert auf der Lösung der Erhaltungs- und Impuls-Gleichungen für jede Phase (Wasser undPartikel) und integriert dann die Interaktion zwischenPartikeln und Wasser. Ein Vergleich mitden experimentellen Konfigurationen von Villaretet al. (1997, 1998), ohne Strömung, zeigt, dassdie verschiedenen Schritte des Phänomens rechtgut ohne Modellierung, The port structures are often established in areaswhere water levels are fairly low, especially in estuaries.It is then necessary to perform dredging toallow ships accessing to the docks. The dredgedsediment is released over a predefined depositzone. Because of the concentration of the sedimentcloud appearing during the release, morethan 350 g/l at the beginning, there is an impacton the environment. The chemical composition ofwater is affected directly.After the release, the sediments settle under acloud of very high concentration. This settling stepis followed after impact on the bed by the formationof turbidity current. The purpose of this work is tostudy the phenomenon via numerical simulationsby using a two-phase model of sediment transport[Barbry et al., 2000 ; Chauchat et al., 2008 ;Nguyen et al., 2009]. It is based on the solving ofconservation and momentum equations for eachphase (water and particles) and then integratesthe interaction between the particles and the water.A comparison with the experimental configurationof Villaret et al. (1997, 1998), without current,shows that the different steps of the phenomenonare quite reproduce without turbulence modelling., La gestion des clapages (ou rejets en mer des produits de dragage) constitue une problématique environnementale et économique importante pour les estionnaires des voies navigables et des infrastructures portuaires. Moins coûteuses qu’un stockage à terre, ces opérations peuvent induire des nuisances sur l’environnement notamment en provoquant un accroissement local de la turbidité et en ensevelissant les habitats de la faune aquatique. Le phénomène de clapage comporte principale ment trois phases [Boutin, 2000]: la phase de chute (soumise aux courants) ; l’impact sur le fond et la génération d’un courant de densité ; la propagation des courants de densité et la décantation des sédiments.

International audience; This paper presents the design and the experimental tests of an ultra-capacitor pack used as an energy storage system in a small hybrid electric vehicle. This design consists in calculating the capacitance and the power of the capacitors, which are necessary to store kinetic energy during deceleration of the vehicle and then to accelerate the vehicle. In a second part, experimental tests are achieved to determine the real parameters of the capacitor pack electric model [1] in order to validate the manufacturer data. Influence of temperature on those experimental data is investigated too. Finally, the authors determine the energetic behaviour of the ultra-capacitors: they have measured an efficiency of around 95% during capacitors charge and discharge.

International audience; Many surfactants and polymers are considered as excellent drag reducing agents. This phenomenon induces a significant head loss reduction compared to the pure solvent. In this study an aqueous solution of CTAC/NaSal (CetylTrimethyl Ammonium Chloride and Sodium Salicylate) is used in turbulent pipe flow system. Drag reduction experiments were carried out for different experimental conditions using pressure drop measurements. At the same time the spatial velocity distribution was measured and analysed using particle image velocimetry (PIV).

International audience

International audience; In this paper, the authors propose an approach to the problem of the energy management in ECCE laboratory hybrid vehicle project. ECCE is a series hybrid vehicle, which currently has three sources of energy: two diesel motors each coupled with an alternator and a battery module of rated voltage DC 540V. This contribution is focused on the energy coupling between batteries and two supercapacitors modules. The authors present a strategy for coupling these power sources with the batteries in order to find the best compromise between sizes of the on-board devices, dynamics of the supply and efficiency of the energy storage. The target is to provide 200kW power during 20s from the supercapacitors modules.

International audience; This paper presents a new electric power management methodology between super capacitors and batteries for the ECCe test bench. ECCE is an experimental Hybrid Vehicle developed at L2ES laboratory in collaboration with the Research in Electrical Engineering and Electronics Center for Belfort (CREEBEL) and other French partners. This hybrid vehicle has currently lead-acid batteries with a rated voltage at 540 V, two ICE motors couples to electric generators. These alternators are couples to DC-link by rectifiers. The main objective of this study is to associate two super capacitors modules to DC-link of this experimental test bench by using DC/DC Converters topologies. The super capacitors module is made of 108 cells with a maximum voltage of 270 V. The authors propose an original power management strategy between super capacitors and batteries by using the RST polynomial correctors. The Hybrid Vehicle power management algorithm is developed for two DC/DC converters topologies. The advantage of polynomial correctors RST in the power management is compared to classical PI correctors.

International audience; This chapter proposes an advanced thermal model for lithium-ion battery technology. The model is able to predict the surface temperature of lithium-ion battery cell accurately. The model exists of electrical components such as thermal capacitance, inside thermal resistance and convective thermal resistance.In this chapter, a new methodology is presented that allows to determine the parameters of the thermal model. Then, the model has been calibrated and validated at different environmental conditions. According to the validations results, the error of the simulation compared to experimental results is less than 1 °C. Furthermore, the model has been extended to a novel electrothermal model for enhancing of the model performances. Particularly, the association of the electrical model with the thermal model is of high importance due to the change of the battery parameters such as internal resistance in function of state of charge, temperature and current rates.

International audience; A judicious study with regard to a more efficient energy management on board of an electric vehicle (EV) is discussed in this paper. This analysis follows the present trend in the field, knowing that the major drawback of the EV is the autonomy problem. Thus, by using a hybrid energy source (formed by ultracapacitors and battery) and with a proper current control (of polynomial type) one can get the proper energy management which will increase the lifetime of the battery. Through numerical simulations and tests at a reduced scale, the authors present a successfully energy management with regard to the DC/DC - battery and DC/AC - electrical machine subsystems operation, used on board of an EV.