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Phase change materials (PCM) are promising technology to store thermal energy at a constant temperature. A large amount of energy can be stored or released in latent heat form during the transition of material from one phase to another. Despite the great benefits, most PCMs have their own limitations i.e., low phase change enthalpy, poor specific heat and thermal conductivity, supercooling, volume change, phase segregation, etc. Consequently, efficient thermal energy storage requires improving the thermophysical properties of PCMs. The present study is a comprehensive review of existing techniques for PCMs thermophysical properties enhancement. The research progresses on adding zero, one, two, and three-dimensionally structured additives to PCM is assessed to improve the thermal transport by enhancing the PCM effective thermal conductivity. The enhancement of latent heat of fusion and specific heat using various additives is also discussed. Further, the latest techniques on supercooling and phase segregation reduction are also presented. Last, the modelling of the novel composite materials formed by combining a PCM with other materials is presented. Despite the fact that the majority of these methods are still in the research and development stage, some of them have the potential to be commercialized in the near future. Reliable and efficient PCMs are exceptionally useful for storing solar energy and industrial waste heat, especially for constant temperature applications.

Worldwide, the residential buildings are consuming a considerable amount of energy. The high potential of buildings towards energy efficiency has drawn special attention to the passive design parameters. A comprehensive study on optimal passive design for residential buildings is presented in this paper. Twenty-five different climates are simulated with the aim to produce best practices to reduce building energy demands (for cooling and heating) in addition to the life-cycle cost (LCC). The occupants' adaptive thermal comfort is also improved by implementing the appropriate passive cooling strategies such as blinds and natural ventilation. In this respect, the implemented methodology is composed of four phases: building energy simulation, optimization, Multi-criteria Decision Making (MCDM), sensitivity study, and finally an adaptive comfort analysis. An optimal passive solution of the studied building indicates the potential to save up to 54%, 87% and 52% of the cooling demands (Qcool), heating demands (Qheat) and LCC respectively with respect to the initial configuration. The obtained optimal passive parameters are validated with the National Renewable Energy Laboratory NREL benchmark for low energy building's envelope. Additionally, the integrated passive cooling strategies have demonstrated its competency since it leads to a significant overheating decrease.

Two vital factors in energy production are constantly sought at a time where global environmental awareness has potentially increased: energy efficiency and economy. In the absence of renewable or green energy, multigeneration systems are a necessity, delivering multiple forms of usable energy in one system package. For such systems to be realized, it is important that they are optimally designed and selected according to end-user preferences but also meeting the energy, economy, and environment conditions or obligations. Proper design should take into consideration such evaluation criteria, and be optimized correspondently, after which a decision should be made regarding the most appropriate system to be employed. This chapter will go through the different aforementioned design, optimization, and decision-making methods and their application as referred in literature.

Net-zero energy buildings (NZEBs) have been considered as an efficient solution to limit the growing energy consumption and pollution emissions from buildings. The configurations and the capacities of the implemented renewable energy systems in NZEBs should be wisely selected to ensure the intended performance objective. This study aims to optimize, investigate and compare six renewable energy solution sets for designing NZEBs in three different climates: Indore (cooling dominant), Tromso (heating dominant), and Beijing (mixed climate). The optimization is carried out using a multi-criteria decision-making methodology. The implemented methodology is composed of two phases. In the first phase, the optimal sizes of solution sets in each climate are derived and analyzed. The effectiveness of optimal solution sets is evaluated with respect to economy, environment, energy and grid stress. In the second phase, recommendations for each region are offered according to the overall performance evaluation results. The evaluation criteria include life cycle cost, payback period, levelized cost of energy, CO2eq emissions, grid interaction index, load matching index, and total energy consumption. The analyses show that, in Indore (hot climate), it is recommended to utilize the solution set composed of air source heat pump for cooling and flat plate solar collectors for domestic hot water (DHW) production. In Tromso (cold climate), the use of a biodiesel generator is promising to produce both electricity and hot steam for heating as well as DHW use. In Beijing (mixed climate), it is recommended to utilize electric chillers for cooling and natural gas condensing boiler for heating and DHW usage.

International audience; Integrating heat exchanger pipes with structural foundations in one system has created a new renewable solution for buildings’ thermal loads. However, the interaction between thermal and geotechnical loads makes their design more complex and challenging. This review-study represents the current state of knowledge about the thermal and thermo-mechanical behaviors of energy piles. It also investigates the key parameters that affect their design concerning the piles’ dimensions, the arrangement of pipes, concrete admixture, and fluid characteristics. It is found that the thermal efficiency improves significantly by increasing the number of pipes inside the piles and by adding thermally conductive materials to the concrete within acceptable limits. Besides, this paper reviews most of the studies conducted on optimizing vertical ground heat exchangers coupled with heat pumps. Objective functions, decision variables, design constraints, and optimization methods are specified and listed. It is concluded that a multi-objective optimization is highly recommended to enhance the dual performance of an energy pile system coupled with a heat pump using the 4E evaluation criteria (energy, exergy, economy, and environment) while ensuring the safety of the foundation under thermal cyclic loads.

International audience; Cooling demand in the building sector is growing rapidly; thermal energy storage systems using phase change materials (PCM) can be a very useful way to improve the building thermal performance. The right use of PCM in the envelope can minimize peak cooling loads, allow the use of smaller HVAC technical equipment for cooling, and has the capability to keep the indoor temperature within the comfort range due to smaller indoor temperature fluctuations. This article presents an overview of different PCM applications in buildings for reducing cooling loads under different climate conditions, and the factors affecting the successful and the effective use of the PCM. Many drawbacks have been found in PCM applications, mainly the intense impact of summer weather conditions over the PCM performance, which prohibits its complete solidification during night, and thus, limiting its effectiveness during the day. Proposed solutions are reviewed in this article. Finally, a topology diagram is presented to summarize the steps leading to an effective use of PCM in building applications.

International audience; Electrical energy demand is continuously increasing due to the global population growth and improved living standards. This proposes a growth in the potential for the use of tri-generation systems in residential sector, due to their ability to produce both useful thermal energy and electrical power from a single source. In Lebanon, the electrical capacity shortage has created an informal back-up self-generation systems, mostly are diesel power generators, estimated to represent about 30% of all electricity generated. This paper presents a simulation study, using TRNSYS software, of tri-generation systems working on diesel engines to supply the different residential energy demands. The recovered percentage of the exhaust gas wasted energy is determined and an optimizing study is carried out to find the optimum storage tanks sizes of the recovered thermal energy. Results show that tri-generation systems are found to make diesel power generators more energy-efficient and thus reduce greenhouse gases emissions.

International audience; In this article, a simplified model for melting of a phase change material (PCM) in presence of natural convection and radiation is presented. A modified enthalpy method is adopted to solve the phase change problem, the natural convection occurring in the liquid PCM is accounted for using the enhanced thermal conductivity approach coupled with the scaling theory, and the absorbed shortwave radiation flux is added into the energy equation as a source term using a simplified solution algorithm. Two dimensional implicit finite volume method is used to solve the energy equation. First, the simplified model for melting with natural convection is validated using a CFD model, in addition to experimental and numerical benchmark solutions for a test case. Then, the simplified model for melting with combined natural convection and radiation is applied to the melting of a fatty acid eutectic filled in glass bricks, which will be used later to model the annual thermal behavior of a special translucent façade. This complete model is validated against the lattice Boltzmann-discrete ordinate method LBM-DOM. It was shown that (1) the proposed simplified model is simple to implement and its simulations run significantly faster than those of CFD models and LBM-DOM model. Consequently, it can be easily integrated into an energy simulation tool for yearly performance evaluation, (2) during PCM melting process, natural convection has a noteworthy role as it enhances the average fraction of liquid and the position of the melting front, (3) shortwave radiation enhances the average liquid fraction.

International audience; The conception of net zero energy buildings (NZEB) has been introduced to limit energy consumption and pollution emissions in buildings. Classification of NZEB is based on renewable energy (RE) supply options, energy measurement process, RE-sources location, and balances whether are energetic or exergetic. In general, it is traditionally agreed that there are three main steps to reach the NZEB performance, starting through the use of passive strategies, energy efficient technologies, and then RE generation systems. Then, these three steps could be accompanied with the smart integration of advanced efficient energy technologies. A state of the art shows that the main ZEB studies are related to: energy savings, reduce electric bills, energy independence, pollution reduction, and occupants comfort, in addition, others are more interested in the aesthetic aspect by combining modern technologies with innovations to achieve high energy and sustainability performance. Building optimization is a promising technique to evaluate NZEB design choices; it has been adopted to choose the perfect solution to reach the zero energy performance through the optimization of an objective function related to energy (thermal loads, RE generation, energy savings) and/or environment (CO2 emissions) and/or economy (life-cycle cost (LCC), net-present value (NPV), investment cost). This paper starts by presenting the global energetic and pollution challenges the world faces. Moreover, it shows, to the best to the author’s knowledge, the existing NZEB definitions and the corresponding case studies investigated in 8 different climatic zones (humid continental, humid subtropical, Mediterranean, moderate continental, moderate continental, marine west coast, tropical, semi-arid and hot), the paper also focus on the importance to treat each climate separately. Even in the same country, two or more climates may co-exist. NZEBs drawbacks are also presented. Furthermore, different optimization problems are reviewed in the last section. Building energy optimization methods are employed to obtain the ideal solution for specific objective functions which are either related to energy, and/or environment and/or economy. Optimization variables are distributed between passive and/or RE generation systems. Finally, a table summarizing the most commonly used electric and thermal RE applications which yield to the zero energy balance in each climate, as well as three flowcharts are presented to summarize the whole three-stage procedure, to reach NZEB, starting from building designing, passing through the optimization procedure, and lastly categorizing the zero energy balance.

International audience; Enhancing efficiency, meeting environmental standards, and preserving fuel resources are highly important objectives in power generation systems, at a time where world is endangered by several energetic, environmental, and health crises. Thus, better designs are constantly sought to increase the performance of such systems. In this study, an environment friendly trigeneration system based on solid oxide fuel cell (SOFC) is selected and designed for domestic applications. Negligible emissions are thus recorded as the SOFC is fueled solely by hydrogen. The system is modeled following three steps: the energy simulation of residential building to determine its demands, the system’s prime mover–SOFC, and the trigeneration recovery system ensuring the maximum coverage of heating, cooling, and domestic hot water loads respectively. The system is then evaluated under the 4-E assessment criteria: energy, exergy, economy, and environment. Depending on these criteria, the system is multi-objectively optimized. Two operation strategies are adopted: off-grid following electrical load and on-grid base load operations. Optimization results show that the trigeneration system is energetically and economically superior and performs well under both strategies. The maximum energy and exergy efficiencies (65.2% and 45.77%) and minimum system cost rate (22.2 cents/kWh) are obtained under on-grid base load operation.

International audience; The challenge in Zero energy building (ZEB) design is to find the best combination of design strategies that would face the energy performance problems of a particular building. This paper outlines the methodology and the cost-effectiveness potential for optimizing the design of net-zero energy building (NZEB) in a cold climate region in Lebanon; Cedars. Specifically, the non-sorting genetic algorithm (NSGA-II) is chosen in order to minimize thermal, electrical demands and life cycle cost (LCC) while reaching the net zero energy balance; and thus getting the Pareto-front. A ranking decision making technique (ELECTRE III) is applied to the Pareto-front so as to obtain one optimal solution. A wide range of energy efficiency measures are investigated, besides solar energy systems are employed to produce required electricity and hot water for domestic purposes. The results clearly indicate that, for designing a residential NZEB in cold climate, it is essential to minimize the space thermal load through a building envelope with high thermal performance. Envelop high level of insulation is an essential step to decrease the high heating demand. Building thermal loads are decreased by 33.19%. Moreover the LCC is decreased by 31.09%.

International audience; Energy demands and fuel costs are continuously increasing which necessitates either finding new energy resources or improving current energy systems. Multi-generation systems as cogeneration (CHP) and trigeneration (CCHP) are interesting solutions that can enhance energy generation performance and fix some interrelated reliability, safety, and flexibility issues. In this regard, many prime mover technologies are available in which the choice between each is greatly dependent on end-user conditions and preferences. Yet, it is prior to choose whether cogeneration or trigeneration is more suitable. Thus, this paper reviews the main differences between CHP and CCHP systems in most available prime mover technologies, after which a selection table is proposed in order to make appropriate multi-generation system installation choices, depending on specific case study parameters. In general, CHP and CCHP systems yield positive technical and environmental performance impacts.

International audience; This paper presents a review of the energy status, conventional and renewable, in Lebanon and illustrates their problems with the suggested recommendations. In addition, a detailed review of the principal directorates of the electricity of Lebanon Company (EDL) is also presented all along with the existing problems and recommended solutions. An economic, environmental optimization of different power sources is studied, where three scenarios are introduced based on the fuel source of different CCGT power plants. The results emphasized on the maximum possible use of wind energy and natural gas in electricity generation. Based on the optimization study, a five-year master plan for electricity generation is modeled. The suggested plan has an investment capital cost of 5553 M$ with the savings and additional incomes being 5900 M$ compared to EDL financial status in the adopted base year, 2009. In addition, this plan exceeds the trend to introduce a 12% share of renewable energy in the power sector by 2020, where the share is supposed to be about 15% out of the total installed capacity before this date. The concluding remarks highlight the role of politics in the development of the energy sector.

The hybrid cooling system has proved to be an energy saving technology for building air conditioning. Numerous systems combining different cooling processes or cooling machines have been proposed and investigated in the literature. A properly selected hybrid cooling system offers a great reduction in energy consumption and a coefficient of performance improvement varying according to different climates and system designs. This paper provides a detailed review of existing hybrid cooling systems with their corresponding individual cooling machines. A brief state of the art of the most common individual cooling systems in hybrid cooling for building use is firstly presented. Then, the hybrid cooling systems are classified into five main categories according to the combination of cooling processes or machines: Vapor compression based cooling, absorption based cooling, adsorption based cooling, desiccant-evaporative and multi-evaporator cooling. In each category, the studied configurations and the benefits of each hybridization method are presented. It is found that each hybrid system combines the advantages of the different cooling processes used. However, a hybrid system could have a negative repercussion if it does not match the climatic zone where it will be used. Consequently, a selection scheme to recommend the best hybrid cooling system for minimum energy consumption and pollution emissions in buildings according to different parameters is proposed.

The fatigue life of a component is defined as the total number of cycles or time to induce fatigue damage and to initiate a dominant fatigue flaw which is propagated to final failure.(Shigley & Mischke 2002) The aim of this project is to calculate the total fatigue life of metallic structures under cyclic loading by applying equations found by Basquin and Manson-Coffin. The local stresses and strains necessary for the calculation are determined by the finite element method. Former studies concerning this subject have used analytical methods to find the local conditions at the critical section. The analytical methods, based on Neuber and Molski-Glinka’s approaches, permit the calculation of the local stresses and strains at the critical section of the structure’s geometry as a function of the nominal stress (forces) applied. For the finite elements method, ABAQUS is used to determine the local conditions at the critical section of a T-shaped model.

The aim of this paper is to comprehensively study the mathematical modeling applied for phase change taking into consideration the convection in liquid state during melting. Different methods used to model the phase change with convective motion of liquid phase are discussed. First, models based on CFD (computational fluid dynamics) are presented; the solution of Navier-Stokes equations determines the effect of convection in a Newtonian fluid. Secondly, simplified methods are presented, where the convection in the liquid phase change material (PCM) is modeled without the need of the full solution of Navier-Stokes equations. It is clear that the methods based on CFD models are more accurate and express the realistic behavior of the convection effect; however their computational time is very long compared to simplified one.

International audience; A simple model for a detached house in Beirut is optimized using a building energy simulation program to minimize two objective functions: the annual thermal demand; and the difference between the total electrical load and the on-site electricity generated from the renewable energy system. The optimization variables are: insulation thickness of external walls and roof, thickness of roof reinforced concrete, size of windows on each façade, number of solar collectors of the domestic hot water system (SDHW), SDHW circulating pump flow rate, and number of panels of the Photovoltaic system (PV). The main optimization constraint adopted is the thermal comfort criterion. Results of the optimization shows that the exclusion of cost parameter may lead to unfeasible solutions even if the net zero balance is theoretically achieved.

International audience; Electricity, heating, and cooling are the three main components constituting the tripod of energy consumption in residential, commercial, and public buildings all around the world. Their separate generation causes higher fuel consumption, at a time where energy demands and fuel costs are continuously rising. Combined cooling, heating, and power (CCHP) or trigeneration could be a solution for such challenge yielding an efficient, reliable, flexible, competitive, and less pollutant alternative. A variety of trigeneration technologies are available and their proper choice is influenced by the employed energy system conditions and preferences. In this paper, different types of trigeneration systems are classified according to the prime mover, size and energy sequence usage. A leveled selection procedure is subsequently listed in the consecutive sections. The first level contains the applied prime mover technologies which are considered to be the heart of any CCHP system. The second level comprises the heat recovery equipment (heating and cooling) of which suitable selection should be compatible with the used prime mover. The third level includes the thermal energy storage system and heat transfer fluid to be employed. For each section of the paper, a survey of conducted studies with CHP/CCHP implementation is presented. A comprehensive table of evaluation criteria for such systems based on energy, exergy, economy, and environment measures is performed, along with a survey of the methods used in their design, optimization, and decision-making. Moreover, a classification diagram of the main CHP/CCHP system components is summarized. A general selection approach of the appropriate CCHP system according to specific needs is finally suggested. In almost all reviewed works, CCHP systems are found to have positive technical and performance impacts.

An improved analytical modeling, three stages homogenization method “3SHM”, of a 2.5D interlock woven composite is proposed. The development of the analytical model based on mixed iso-strain and iso-stress assembling models (the stiffness and the compliance averaging models) is presented. A finite element (FE) modeling is carried out in order to use its results in the development of the analytical model. It is proved that a model based only on an iso-strain condition could not give accurate results, while a mixed iso-strain and iso-stress model yields more accurate estimations. the developed homogenization method as well as the geometrical modeling, that takes into account the real geometry of undulated yarns, proposed by the analytical model leads to very good agreement in comparing with results obtained from FE models and available experimental data from the literature.

Heat pump systems can be found in high number of applications. One of these is the production of domestic hot water. This paper presents a quasi-steady state simulation model to predict the performance of a simple air source heat pump water heater (ASHPWH). The mathematical model consists of submodels of the basic system components, namely, evaporator, condenser, compressor, and expansion valve. These submodels were built based on fundamental principles of heat transfer and thermodynamics. The model was coded into MATLAB software and used to predict system parameters of interest such as hot water temperature, evaporating and condensing pressures, heat rejected in the condenser, electric power input, heating seasonal performance factor, and coefficient of performance.

Buildings' optimization is a smart method to inspect the available design choices starting from passive strategies, to energy efficient systems and finally towards the adequate renewable energy system to be implemented. This paper outlines the methodology and the cost-effectiveness potential for optimizing the design of net-zero energy building in a French city; Embrun. The non-dominated sorting genetic algorithm is chosen in order to minimize thermal, electrical demands and life cycle cost while reaching the net zero energy balance; and thus getting the Pareto-front. Elimination and Choice Expressing the Reality decision making method is applied to the Pareto-front so as to obtain one optimal solution. A wide range of energy efficiency measures are investigated, besides solar energy systems are employed to produce required electricity and hot water for domestic purposes. The results indicate that the appropriate selection of the passive parameters is very important and critical in reducing the building energy consumption. The optimum design parameters yield to a decrease of building's thermal loads and life cycle cost by 32.96% and 14.47% respectively.

This study presents an evaluation of a solid oxide fuel system modeled with its energy balance of plant components in order to recover its exhaust waste heat and develop a combined cooling, heating, and power system. A hydrogen-fueled SOFC is modeled in MATLAB and a 3D drawn building are imported into TRNSYS where system performances are assessed. An optimization approach is employed to find the best system sizing. Energetic and environmental assessments shows better performance as the system size increases which suggests the necessity of an economic study application.

International audience; This paper presents the dynamic modeling of a domestic hybrid water heating system. The system is composed of a solar collector, a heat pump water heater, a wind turbine, a battery and a hot water storage tank. Both air-source and geothermal-heat pumps are investigated. Detailed mathematical dynamic models of the individual components are presented and validated. Simulations for typical days in summer and winter for Beirut and Cedars, two Lebanese locations with different meteorological and demographic conditions, are conducted using Matlab software. A renewable coverage factor (RCF) is defined, representing the renewable energy share with respect to the total delivered energy. Results reveal that the proposed hybrid system is capable of securing all hot water needs in all case studies and RCF is always above 63%. Furthermore, an energetic, economic optimal management model is developed for the proposed hybrid system. It is applied to the considered case studies, where results illustrate the optimum size of each of the system components as well as the optimum energy-flow distributions among them over two investigated time periods, five and ten years. It is noticed that the initial cost of the hybrid system is acceptable and important annual savings are obtained.

International audience; Water heating contributes an important proportion of residential energy consumption all around the world. Different kinds of domestic hot-water production systems exist. The operational cost, environmental effect and performance of these systems differ according to various energy sources, climates, system types and system designs. Hence, the proper choice of a domestic hot-water system could save energy, protect nature and reduce operational costs, significantly. This paper illustrates, to the best of the author's knowledge, the existing water-heating systems all along with the principle, advantages, disadvantages and state-of-the-art for each. Six different categories were presented, namely wood, oil/gas, electric, heat pump, solar and instantaneous systems. The heat-pump systems were further classified into several groups, namely air source, ground source, solar assisted, ground source-solar assisted, photovoltaic–thermal and gas-engine driven systems. In addition, concerning solar water heating, different types of systems and collectors were presented and reviewed. Principal conclusions from the review are outlined and a general approach to recommend the appropriate water-heating system is proposed.

International audience; This paper presents a dynamic simulation model to predict the performance of an ASHPWH (air source heat pump water heater). The developed model is used to assess its performance in the Lebanese context. It is shown that for the four Lebanese climatic zones, the expected monthly values of the average COP (coefficient of performance) varies from 2.9 to 5, leading to high efficiencies compared with conventional electric water heaters. The energy savings and GHG (greenhouse gas) emissions reduction are investigated for each zone. Furthermore, it is recommended to use the ASHPWH during the period of highest daily ambient temperatures (noon or afternoon), assuming that the electricity tariff and hot water loads are constant. In addition, an optimal management model for the ASHPWH is developed and applied for a typical winter day of Beirut. Moreover, the developed dynamic model of ASHPWH is used to compare the performance of three similar systems that differ only with the condenser geometry, where results show that using mini-condenser geometries increase the COP (coefficient of performance) and consequently, more energy is saved as well as more GHG emissions are reduced. In addition, the condenser “surface compactness” is increased giving rise to an efficient compact heat exchanger.

International audience; This paper presents a brief review of the conventional and renewable energy statuses, in Lebanon, as well as of the principal problems facing the electricity of Lebanon Company (EDL). In addition, an analytical-critical review of the latest three official Lebanese electricity plans is presented. Furthermore, two future electricity generation plan-scenarios for Lebanon are investigated, where multi variables are examined, namely: cost, environment and tariff. First, an economical-environmental optimization is carried out, where two reasonable scenarios are introduced based on the fuel source of CCGT power plants. Results revealed that the investment in wind energy and natural gas for power production should be a main concern in the future. Second, an optimization of the average electricity tariff for each of the two investigated generation scenarios is studied, where three different approaches are illustrated. Results confirm that all tariff plans are acceptable and convincing, and that the use of natural gas in CCGT plants is always preferred against gasoil. Moreover, the optimized average tariff is maximally a double of the current EDL average tariff, which is very convincing compared with the actual cost of electricity for the current Lebanese electricity sector.

The local approach method is used to calculate the fatigue crack initiation/early crack growth lives (N i ) in high strength structural steel weldments. Weld-toe geometries, welding residual stresses and HAZ (heat affected zone) cyclic mechanical properties are taken into account in the N i estimation procedure. Fatigue crack initiation lives are calculated from either a Basquin type or a Manson-Coffin type equation. The local (HAZ) stress and strain amplitudes and the local mean stress are determined from an analysis based on the Neuber rule and the Molski-Glinka energy approach. The accuracy of the different methods is evaluated and discussed. Finally the previous methods are used with HAZ cyclic mechanical properties estimated from hardness measurements.

It is seen that 2.5D interlocks are particular reinforcements for high advanced applications (i.e., spatial and aeronautics fields) that are believed to have a high structural potential. This kind of reinforcement entails to consider the composite as a structure because interlocks are built by crossing the warp yarns with the weft (or fill) yarns in the three directions. In this article, a new numerical and analytical model is proposed. To evaluate the mechanical behavior, one may obtain numerically, the anisotropic elastic engineering constants from a finite element model (FEM). This technique of virtual testing consists of modeling the composite at the meso-scale to obtain a macro-scale response with a stress—strain analysis. At the moment, numerical simulations of such materials mainly involve geometrical models and automated tetrahedral meshes that make it difficult to cope with the orthotropic behavior of yarns materials. We thus propose a new meshing methodology to build an elementary volume made of tetrahedra for the isotropic matrix and of mapped hexaedra for the transversely isotropic yarns in order to achieve the FE discretization. A new analytical model is also been proposed, based on a geometrical modeling of the yarns using sinusoidal function and on homogenization at the macrolevel based on both iso-strain and iso-stress assumptions. This model allows the estimation of stiffness matrix of the composite in terms of the properties of its constituents and the geometry of the fabric. Two 2.5D interlock composites from the ‘layer—layer’ family are studied where the nine engineering constants are evaluated. The FEM and the analytical model show a good agreement with each other and with available in-plane Young’s modulus and Poisson’s ratio experimental results.

Heat pump systems can be found in high number of applications. These systems utilization include food preservation, heat removal from industrial processes such as chemical production, and numerous other special applications in the construction and manufacturing industries. Heat pump systems typically consist of many different components; each component may be produced by a different manufacturer. The operational data provided by the different manufacturers for each component is used by system designers to specify installation and operational procedures of the system. Often times, the optimum control of an individual piece of equipment results in sub-optimal system performance due to unforeseen interactions between the different system components. It is important to identify and monitor key parameters of the system, such as power consumption and refrigeration effect, in order to optimize the performance.

International audience; This paper presents a detailed review of EDL (Electricité du Liban). It displays the institution's technical problems at the level of electricity generation, transmission and distribution as well as the administrative and financial states and suggests several recommendations. It is obvious that EDL suffers a great shortage in its generating capacity and human resources and would not be effective without conducting a national strategy that includes radical solutions.