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Low-temperature flue gases (

To provide information for greenhouse gas reduction policies, the California Air Resources Board (CARB) inventories annual emissions of high-global-warming potential (GWP) fluorinated gases, the fastest growing sector of greenhouse gas (GHG) emissions globally. Baseline 2008 F-gas emissions estimates for selected chlorofluorocarbons (CFC-12), hydrochlorofluorocarbons (HCFC-22), and hydrofluorocarbons (HFC-134a) made with an inventory-based methodology were compared to emissions estimates made by ambient-based measurements. Significant discrepancies were found, with the inventory-based emissions methodology resulting in a systematic 42% under-estimation of CFC-12 emissions from older refrigeration equipment and older vehicles, and a systematic 114% overestimation of emissions for HFC-134a, a refrigerant substitute for phased-out CFCs. Initial, inventory-based estimates for all F-gas emissions had assumed that equipment is no longer in service once it reaches its average lifetime of use. Revised emission estimates using improved models for equipment age at end-of-life, inventories, and leak rates specific to California resulted in F-gas emissions estimates in closer agreement to ambient-based measurements. The discrepancies between inventory-based estimates and ambient-based measurements were reduced from -42% to -6% for CFC-12, and from +114% to +9% for HFC-134a.

Vehicle owners in the United States can recharge their vehicles' air conditioning systems with small containers of hydrofluorocarbon-134a (HFC-134a, CH 2 FCF 3 ). This refrigerant, with a Global Warming Potential of 1430, may be emitted to the atmosphere during the recharging operation and from the residual heel in partially used containers, contributing to climate change. A field study was conducted in southern California to quantify the rate of refrigerant emissions from nonprofessional recharging practices and identify emission mitigation opportunities. Based on the results of the study, an average of 489 g of HFC-134a is used when recharging the sample vehicles with an average nominal charge of 858 g. An average 67% of the container content is effectively charged into the systems, 11% of the refrigerant is released during service, and the remaining 22% is left in the containers after operations are completed. A comparison with two other independent studies indicates that the findings of the current study may be applicable not only to southern California, but also to the entire U.S.

Cryo Pur technology uses cryogenic separation to remove water vapor and carbon dioxide from biogas, in order to obtain bio-methane. To cool down the biogas at a very low temperature, a fin-and-tube heat exchanger is designed. In order to improve the fin-and-tube heat exchanger performance, a model is developed to investigate the material and fin pitch on frosting carbon dioxide. This paper will study the effect of the tubes and the fins material, and the fin pitch effect. The purpose is to extend the duration of a frosting cycle.

International audience; The frosting fin-and-tube heat exchanger used in this study is implemented in the dehydration process of a biogas upgrading pilot. Water is separated from the biogas by frosting it at very low temperatures on the cold surfaces of the fin-and-tube heat exchanger. Once frosted, a defrosting system is used to remove water from the process. The main interest of this study is the frosting system. The effects of the biogas velocity, fin material, tube material and frost layer thickness on the performance of the fin-and-tube heat exchanger are investigated. Increasing the biogas velocity tends to increase the frosting layer thickness and the external pressure drop. This will lead to decrease the heat exchanger performance and the frosting cycle duration. The thermal conductivity of the fins and tubes has a major effect on the performance of the heat exchanger. Higher thermal conductivity decreases the heat exchanged surface. A numerical model has been developed, then numerical and experimental results extracted from a biogas upgrading pilot are compared.

International audience; Analysis of various existing correlations of predicting local heat transfer and pressure drop in minichannels is performed. Heat transfer coefficient is compared to experimental results. Tests are conducted in a 6-channel tube. Channels are rectangular with 1.1 mm hydraulic diameter. Test parameters were varied in the following ranges: mass flux G = 20-100 kg m -2 s -1, heat flux q" = 2-15 kW m -2, and vapor quality 0-1. Two working fluids are used R-134a and R-1234yf. Contrary to previous studies, in this study convective boiling was identified as the dominant boiling regime. The effect of the critical heat flux on the heat transfer coefficient for low mass flux is also studied. The realized tests are compared to several correlations. Four different intervals of mass and heat fluxes are detected. A correlation of the heat transfer coefficient is proposed for these different intervals. Highlights: Boiling in minichannels is experimentally studied for low mass fluxes (G < 100 kg m -2 s -1). None of the correlations in the literature can predict the heat transfer coefficient. Convective boiling is dominant for low mass fluxes. Heat transfer coefficient is dependant of mass flux and vapor quality. Critical heat flux and boiling curves are showed. Local dry-out is identified. A new correlation is proposed for convective boiling for low mass fluxes.

International audience; The hybridization of the conventional thermal vehicles nowadays constitutes a paramount importance for car manufacturers, facing the challenge of minimizing the consumption of the road transport. Although hybrid power train technologies did not converge towards a single solution, series/parallel power trains with power-split electromechanical transmissions prove to be the most promising hybrid technology. In fact, these power trains show maximum power train overall efficiency and maximum fuel reduction in almost all driving conditions compared to the conventional and other hybrid power trains. This paper addresses the model and design of the electro-mechanical configuration of one of the most effective HEV power trains: case study of the 2nd generation Prius. It presents the simulation work of the overall operation of the Toyota Hybrid System (THS-II) of the Prius, and explores not only its power-split eCVT innovative transmission system but also its overall supervision controller for energy management. The kinematic and dynamic behaviors of the THS-II power train are explained based on the power-split aspect of its transmission through a planetary gear train. Then, the possible regular driving functionalities that result from its eCVT operation and the energy flow within its power train are outlined. A feed-forward dynamic model of the studied power train is next proposed, supervised by a rule-based engineering intuition controller. The energy consumption of the THS-II proposed model has been validated by comparing simulation results to published results on European, American and Japanese regulatory driving cycles.

International audience; Internal airlift reactors are closed systems considered today for microalgae cultivation. Several works have studied their hydrodynamics but based on important solid concentrations, not with biomass concentrations usually found in microalgae cultures. In this study, an internal airlift reactor has been built and tested in order to clarify the hydrodynamics of this system, based on microalgae typical concentrations. A model is proposed taking into account the variation of air bubble velocity according to volumetric air flow rate injected into the system. A relationship between riser and downcomer gas holdups is established, which varied slightly with solids concentrations. The repartition of solids along the reactor resulted to be homogenous for the range of concentrations and volumetric air flow rate studied here. Liquid velocities increase with volumetric air flow rate, and they vary slightly when solids are added to the system. Finally, liquid circulation time found in each section of the reactor is in concordance with those employed in microalgae culture.

According to the EU regulation 706/2007, the leak flow rate of a Mobile Air Conditioning (MAC) system must be tested based on a qualified method. The Center for Energy and Processes (CEP) has cooperated with ACEA (European Association of Car Manufacturers) in order to establish the test method. Laboratory tests have been undertaken on 40 MAC systems, more than 100 components, and field tests on 40 vehicles. In this paper the laboratory test protocol for leak flow rate measurements of HFC-134a concentration inside a test chamber using infrared techniques is presented. Leak flow rates in standstill and running modes have been studied. Comparing the laboratory tests and the fleet test results a correlation factor has been established to predict annual leak flow rates of MAC systems in real life conditions based on leak flow rates measured in laboratory.

International audience; This study investigates boiling heat transfer and two-phase pressure drop of HFC-152a in a horizontal square mini-channel of 1 mm in diameter. Convection heat fluxes were obtained using an inverse heat transfer method. Tests were performed at a nearly constant system pressure of 600 kPa and under saturated conditions. Local heat transfer coefficients were determined as a function of vapor quality along the length of the test section. Tests were carried out for mass flux ranging from 200 to 600 kg/m2s and for heat flux ranging from 10 to 60 kW/m2. Experimental results were compared to predictive models from the literature for two-phase flow pressure drop and boiling heat transfer. The correlation of Müller-Steinhagen and Heck (1986) was found to give a good agreement for prediction of mini-channel frictional pressure losses. The heat transfer mechanism was found to be dominated by nucleate boiling, and the heat transfer coefficient independent of vapor quality and mass flux. A new correlation for Nusselt number was developed based on the Tran et al. (1996) correlation, which was able to predict the present experimental data with respective average and maximum absolute deviations of 3.7% and 11%.

International audience; A slipping quasistatic model has been developed to evaluate the performance of a greenhouse sludge drying system assisted by a heat pump called "Solar and Heat Pump Sludge Drying System" (S&HPSDS). The model is derived entirely from the conservation laws of mass, energy, momentum and equations of state as well as correlations of heat transfer. Weather data are incorporated in order to evaluate the seasonal performance of the system. The model can be used for many different purposes; this paper focuses on the evaluation of the heating temperature leading to an annual thermo-economic optimum in terms of energy consumption.

Over 80% of cars, light commercial vehicles and truck cabins in Western Europe are equipped with an air-conditioning system based on vapour compression technology. These systems typically use HFC-134a, which has a high global warming potential. The EU has identified mobile air conditioning systems as one of the major sources of HFC emissions and has indicated that the improvement of the design of these systems is one way to reduce their impact on the environment. The Centre for Energy and Processes laboratory has developed a test method and facility to measure compressor leakage under operating conditions. This feature describes the test facility and presents measurements from both new and old compressors made by different manufacturers.

International audience; —Biogas is a promising technology which can be used as a vehicle fuel, for heat and electricity production, or injected in the national gas grid. It is storable, transportable, not intermittent and substitutable for fossil fuels. This gas produced from the wastewater treatment by degradation of organic matter under anaerobic conditions is mainly composed of methane and carbon dioxide. To be used as a renewable fuel, biogas, whose energy comes only from methane, must be purified from carbon dioxide and other impurities such as water vapor, siloxanes and hydrogen sulfide. Purification of biogas for this application particularly requires the removal of hydrogen sulfide, which negatively affects the operation and viability of equipment especially pumps, heat exchangers and pipes, causing their corrosion. Several methods are available to eliminate hydrogen sulfide from biogas. Herein, reactive absorption in structured packed column by means of chemical absorption in aqueous sodium hydroxide solutions is considered. This study is based on simulations using Aspen Plus™ V8.0, and comparisons are done with data from an industrial pilot plant treating 85 Nm 3 /h of biogas which contains about 30 ppm of hydrogen sulfide. The rate-based model approach has been used for simulations in order to determine the efficiencies of separation for different operating conditions. To describe vapor-liquid equilibrium, a γ/ϕ approach has been considered: the Electrolyte NRTL model has been adopted to represent non-idealities in the liquid phase, while the Redlich-Kwong equation of state has been used for the vapor phase. In order to validate the thermodynamic model, Henry's law constants of each compound in water have been verified against experimental data. Default values available in Aspen Plus™ V8.0 for the properties of pure components properties as heat capacity, density, viscosity and surface tension have also been verified. The obtained results for physical and chemical properties are in a good agreement with experimental data. Reactions involved in the process have been studied rigorously. Equilibrium constants for equilibrium reactions and the reaction rate constant for the kinetically controlled reaction between carbon dioxide and the hydroxide ion have been checked. Results of simulations of the pilot plant purification section show the influence of low temperatures, concentration of sodium hydroxide and hydrodynamic parameters on the selective absorption of hydrogen Hamadi Cherif is with the Mines sulfide. These results show an acceptable degree of accuracy when compared with the experimental data obtained from the pilot plant. Results show also the great efficiency of sodium hydroxide for the removal of hydrogen sulfide. The content of this compound in the gas leaving the column is under 1 ppm.

Low temperature refrigeration system for biogas upgrading has been developed by the Cryo Pur company based on cooling biogas in three steps : removing most of the water content at -40°C, removing siloxanes and SVOCs (Sulfuric Volatile Organic Compounds) at -75°C and  frosting CO2  at temperatures varying from -90°C to -120°C. This process transforms typical biogas containing 35% CO2, 5% water vapor and pollutants in a bio-methane containing 2.5% of CO2. This paper studies how a single low temperature refrigeration system is able to cool biogas with an indirect system using low temperature heat transfer fluids. Exergy and energy analysis are used for comparison of several architectures. The exergy study defines the exergy losses and served as guidance for the energy/ pinch analysis which is used for the design of the series of heat exchangers and the appropriate heat recovery. An optimal system could save up to 40 % of the electric consumption of the refrigeration system.Â

Biomethane is produced by removing undesirable components such as water vapor, carbon dioxide and other pollutants in a biogas upgrading process. Frosting the water vapor contained in the biogas is one of the dehydration processes used in a biogas upgrading process. In order to simulate a frost layer on a cold plate, many models have been developed. These models are valid for a limited temperature range. In this study, heat and mass transfer equations were used in a numerical approach to model the frost growth and its densification on the external side of a fin-and-tube heat exchanger. The model used in this study is valid for low temperatures from 0[Formula: see text]C to [Formula: see text]C and lower. The evaporation process of temperature glide refrigerants is also modeled from [Formula: see text]C to [Formula: see text]C. The results show a decreased heat transfer rate during frost mass growth on fins and rows. During its growth, frost layer thermal conductivity is relatively low leading to decrease the heat exchanger performance. On the other hand, frost layer thickness increases the external surface blockage, leading to higher pressure drop on the external side. This model has been validated by comparing numerical and experimental results for the biogas outlet temperature.

International audience; Cryogenic upgrading of biogas aims to provide energetically efficient process for high purity biomethane production, to be injected in the national gas grid or for vehicle fuel uses. Major components of biogas are methane and carbon dioxide, and for particular type of biogas, called landfill gas, important amount of nitrogen is also present. Cryogenic upgrading processes involve dry ice formation [Clodic and Younes., 2002]., thus accurate predictions of solid-liquid, solid-vapor, and solid-liquid-vapor equilibria are fundamental for a correct design of the heat exchanger surface in order to achieve the desired biomethane purity. Moreover, Liquefied BioGas (LBG) production process is particularly interesting for cryogenic upgrading processes due to the low temperature of the obtained biomethane. It consequently requires an accurate knowledge of carbon dioxide solubility in liquid methane to avoid solid deposition. Finally, knowledge on thermodynamic properties of solid CO2 is needed to simulate the process of upgrading through capture of carbon dioxide as a solid on the fins of a heat exchanger.This work proposes original solid-liquid equilibrium measurements for the binary mixture CO2-CH4 and a thermodynamic model able to represent phase equilibria involving a solid phase for binary (CO2-CH4) and ternary mixture (CO2-CH4-N2), to be used in a heat exchanger simulator with solid formation.Experimental data are obtained with a static analytic experimental method at high pressure (8-15 MPa), conditions at which literature data are missing [Riva et al., 2014]. Measures also allowed to indirectly obtain values of thermodynamic properties of the solid CO2 at temperatures at which direct measures are not available in literature.Thermodynamic model, consisting in a solid phase fugacity expression coupled with a cubic equation of state (Peng Robinson EoS), has been calibrated on solid-liquid-vapor data in order to optimize the representation of phase equilibrium at low temperatures, with particular emphasis on the equilibria involving a solid phase.Comparison of model and data shows a good agreement, so it is possible to conclude that the thermodynamic model is able to predict solid formation condition during the biogas upgrading process. Model and thermodynamic properties are thus used into a simplified heat exchanger dynamic simulator for reproducing solid CO2 capture during the cryogenic process.

The article gives an overview of emission models based on global sales data using a top down analysis. It also elaborates on emission models based on demand in specific sectors (a bottom-up approach) including recovery for both refrigeration and foams; it presents how these bottom-up methods are applied. It summarises the measurements of concentrations of relevant gases in the atmosphere and describes how atmospheric concentrations can be calculated from emission data. Consequently it provides a basis for the practical determination of emission data, as well as the comparison of these data with atmospheric concentrations, and is also a summary description of the tools which can be used for the determination of emission data.

The modelling of consumption and emissions of ozone depleting chemicals and greenhouse gases has been a challenge for the communities of both the Montreal and Kyoto Protocols. One of the particular challenges has been the representative modelling of consumption in sectors with substantial delays in emission and the resulting accumulation of ‘banks’. Several experts, including the authors of this paper, have been active in building databases of sources over the last 5 years and have continued to refine estimates as new information has come to light. The decision of the Inter-Governmental Panel on Climate Change to commission a Special Report on factors influencing the interface between the two Protocols has acted as a stimulus to draw conclusions from the current state of knowledge. This paper is the product of this initiative as it relates to two key sectors of delayed emission: refrigeration equipment and insulating foams. As the title indicates, the paper documents the development of consumption, banks and emissions for both sectors and uses these to develop estimates of anticipated atmospheric concentration. These estimates are then compared with measured atmospheric concentrations in order to evaluate the appropriateness of the modelling approaches used and to identify areas where discrepancies remain. Efforts have been made to explain these discrepancies wherever possible, but it is recognised that the process remains one of continuous refinement. The major findings of the work are that emissions of refrigerants and foam blowing agents will continue well beyond the scope of the current study (1990–2015), with banks of 2.5 and 3 million tonnes, respectively, remaining at 2015. However, the composition of each bank is very different because of the more rapid turnover in the refrigeration sector led by higher emission rates and shorter product lifetimes. This means that the CFC component of some blowing agent banks may provide a significant target for reducing climate change impact of future emissions where technical and economic criteria are met. For the refrigeration sector better containment, recovery at end of life, re-use or destruction, but also change of refrigerant are the key options. There is clear evidence that the atmospheric concentration predictions for those fluorinated compounds predominantly used as blowing agents are less certain. This is partially because of the high dependence of the prediction on the emission functions assumed during the long use phase. A small variance can have a significant impact on the outcome. There are also continuing uncertainties about end-of-life scenarios for major market sectors such as the US domestic refrigerator sector. These areas are the focus of continuing study.

International audience; Heat transfer performance prediction by CFD codes is of major interest. Usually air-side heat transfer characteristics of fin-and-tube heat exchangers are determined from limited experimental data. The ability of CFD code to predict flow patterns and thermal fields allows determining the heat transfer characteristics by performing 'numerical experiments'. CFD calculations of a 1-row automotive condenser are compared to experimental results and correlations of the literature matching the fin design and the flow conditions. Calculations are performed for different air frontal velocities. 2D models, with uniformly constant fin temperature overestimate significantly the heat transfer coefficient. 3D models, taking into account tube effects, conjugate heat transfer and conduction through the fin are in better agreement with the experimental results. However, even if an offset in noticed between CFD calculations and the experimental results, the trends are comparable and CFD study permits to reach local information, leading to better understanding of the physical phenomena involved in compact heat exchangers. An attempt for 2D unsteady flow has also been performed. Results are discussed in terms of flow pattern and heat transfer coefficient behaviour.

International audience; Design and optimization of cryogenic technologies for biogas upgrading require accurate determination of freeze-out boundaries. In cryogenic upgrading processes involving dry ice formation, accurate predictions of solid–liquid, solid–vapor, and solid–liquid–vapor equilibria are fundamental for a correct design of the heat exchanger surface in order to achieve the desired biomethane purity. Moreover, the liquefied biogas production process, particularly interesting for cryogenic upgrading processes due to the low temperature of the obtained biomethane, requires an accurate knowledge of carbon dioxide solubility in liquid methane to avoid solid deposition. The present work compares two different approaches for representing solid–liquid, solid–vapor, and solid–liquid–vapor equilibria for the CH4−CO2 mixture. Model parameters have been regressed in order to optimize the representation of phase equilibrium at low temperatures, with particular emphasis to the equilibria involving a solid phase. Furthermore, the extended bibliographic research allows determining the regions where more accurate data are needed.

The cooling towers gather together many factors for bacteria proliferation and possible transmission to human beings. To eliminate dissemination in the atmosphere, the objective of the presented new system is to eliminate the vectorization of bacteria by eliminating the aerosol production and dispersion from cooling towers. A review of the published techniques of aerosol size measurement has been carried out. The most suitable technique is an optical technique relevant to flow and able to accurately determine particle size distributions, number density, and total mass. The aerosol spectrometer principle is based on the diffraction of white light. The first measurements have been realized at the air exit and at 10 cm and 20 cm above the air exit of the cooling tower. Other measurements have been performed to identify the influence of the ventilation velocity in a cooling tower. Additional measurements have been realized with and without the drift eliminators on the same cooling tower and for the same climatic conditions. The measurements done on cooling towers and the modeling of countercurrent flow show that efforts must be concentrated on water distribution and on water recovery. A new concept has been developed by the CEP and Climespace, patented to eliminate aerosol production and any direct crossing of air flow and water flow.

Resume Nous montrons dans un premier temps, a partir de campagnes de mesures, l'augmentation significative de la consommation de carburant, ainsi que des emissions de polluants reglementes, entrainee par la climatisation d'une voiture. Ainsi, pour la consommation en ville, une augmentation moyenne de l'ordre de 3, 1 l aux 100 km est observee, aussi bien pour les vehicules a essence que pour les vehicules Diesel. Pour les polluants, si les effets sont variables d'un modele a l'autre, on peut cependant noter leur tres sensible augmentations en cycle urbain, particulierement l'accentuation des NOx (+48%) et des particules (+64%) pour les vehicules Diesel. Sont presentes ensuite les resultats de mesures au banc d'essais des puissances mecaniques et electriques absorbees par le systeme de climatisation dans differentes conditions de marche du vehicule (suivi de cycles) et pour differents regimes thermiques de fonctionnement du climatiseur (selon la temperature exterieure, la consigne de temperature dans l'habitacle…). Puis nous presentons les resultats du calcul des emissions de polluants et de la consommation de carburant pour une voiture particuliere a moteur a essence de 1,4 litre de cylindree, equipee d'un pot catalytique: ces calculs sont effectues a partir des donn'ees instantanees recueillies sur le banc d'essais. Nous concluons tout d'abord en precisant la necessite de mener des actions de recherche et developpement pour limiter la puissance absorbee par la climatisation qui contribue a amplifier les phenomenes de pollution urbaine, en particulier lors de periodes de forte chaleur favorables au pic d'ozone. Nous attirons d'autre part l'attention des pouvoirs publics sur le besoin de prendre en compte les systemes de climatisation et autres auxiliaires dans les procedures reglementaires de mesures des emissions et de la consommation.

Special Issue: Selected papers from the 11th US annual conference on Carbon Capture, Utilization, and Sequestration; International audience; CO2 capture by antisublimation consists in cooling the flue gases down to the freezing temperature of CO2 and frosting CO2 on a low temperature heat exchanger surface at a temperature range defined by the CO2 concentration in the flue gases and the CO2 capture efficiency. CO2 is then defrosted and recovered in a liquid state. This CO2 capture process by antisublimation is called AnSU®. The CO2 frosting temperature in flue gases is much lower than the triple point of water and therefore before CO2 capture, water contained in flue gases is removed to reach high purity CO2. This paper presents an overview of the antisublimation process and a brief review of test benches that have been set up in laboratory and on industry sites for validation and optimization of the antisublimation process dating back to the first one constructed in 2003. Energy consumption and cost penalty of CO2 capture by antisublimation are evaluated for a coal-fired power plant. A technical and economic analysis has been made and compared to CO2 capture by oxycombustion for a cement plant. Those two processes can be seen as cryogenics options and the detailed comparison gives insight into where energy losses take place and which capture process could be most adapted depending on specifications of the cement industry.

International audience; The solution for dynamic modeling of reheating furnaces requires a burner model, which is simultaneously accurate and fast. Based on the fact that radiative heat transfer is the most dominant heat transfer mode in high-temperature processes, the present study develops a simplified flame representation model that can be used for dynamic simulation of heat transfer in reheating furnaces. The first part of the paper investigates, experimentally and computationally, gas combustion in an industrial burner. Experiments aim at establishing an experimental database of the burner characteristics. This database is compared with numerical simulations in order to establish a numerical model for the burner. The numerical burner model was solved using a commercial computational fluid dynamics (CFD) software (FLUENT 6.3.26). A selection of results is presented, highlighting the usefulness of CFD as a modeling tool for industrial scale burners. In the second part of the paper, a new approach called the emissive volume approach is established. This approach consists of replacing the burner flame by a number of emissive volumes that replicates the radiative effect of the flame. Comparisons with CFD results show a difference smaller than 1 is achieved with the emissive volume approach, while computational time is divided by 40.

International audience; Heat pump systems have gained significant market shares in Europe recently. The control strategy is an asset for the efficient operation of these thermodynamic systems; especially with compact integrated components. The predictive control, which allows fast system stabilization, is based on the description of the system physical behavior. Thus, dynamic modeling is needed for the development of such control. The model has to represent the system response to usual external perturbations met during current operation such as the variation of air temperature and air mass flow rate. The aim of this paper is to present a dynamic model of a thermodynamic system developed in the Dymola environment, which is an object-oriented modeling environment. The heat-pump components are created separately as individual objects, and then connected to form the system. The model of each component is described and the responses to different perturbations are detailed. Simulation results are compared to test results in order to validate the model.

International audience; What will the passenger car fleet look like over the next two decades' As most expected, affordability and convenience are the major drivers of new vehicle technology penetration into the market. Within this scope, vehicle electrification strategy to limit oil dependence and meet the European targets for CO₂ emissions should be cost-effective and convenient to the buyer.This paper will focus first, through different economic models, on the penetration of passenger electrified vehicles (Plug-in Hybrid Vehicles PHVs and Electric Vehicles EVs) in Europe (EU15: 15 European Union member countries) up to 2030. Economic models are based on real-world-use behaviors and driving patterns in order to compute fuel and energy consumption and to estimate total cost of the vehicle including incentives. The economic models use household wages in order to later make conclusions on vehicle technology market shares by vehicle classes. Later, the study investigates how user behavior, fuel cost and electric power prices would impact the electrified vehicle penetration of the car fleet. Furthermore, the impact of electrified vehicle fleet penetration on reduction of CO₂ emissions and on electricity demand is assessed.

International audience; Air cooling and dehumidification can be performed by different means, at various energy costs. Absorption and adsorption cycles are widely used at various temperature ranges. For air dehumidification at negative temperatures (especially less than -20 °C), the adsorption and absorption systems present some drawbacks such as for the energy regeneration cost of the solid desiccant in the case of adsorption and the liquid desiccant loss by evaporation (generally glycol) in absorption, limiting the continuous operation of the system. In classical absorption systems, the brine dilution (due to water transfer from air to liquid) is compensated by adding salts (CaCl 2, LiCl...). A new absorption method is proposed to dehumidify air to -40 °C with a continuous operation without adding salts to re-concentrate the brine solution. The solution is re-concentrated by evaporating the condensed water on a separate cooling tower around ambient temperature. The energy consumption of the system is compared to other possible concentration processes: water boiling and membrane separation.

International audience; Among the general problematic of the HEV power trains, the most critical point is the determination of the power-split ratio between the mechanical and the electrical paths, known as the energy management strategy (EMS). Many EMS are proposed in the literature, and can be grouped in two categories: the local optimization EMS and the global optimization EMS. The local optimization category corresponds to the EMS based on human expertise and the knowledge of the power train components efficiency maps. Thus, the local optimization EMS manages the power train operations by referring to predefined rules. The drawback of such strategies is that it brings an instantaneous fuel consumption optimization, and does not fully optimize the fuel consumption over the whole trip. Therefore, additional fuel savings are still possible. This paper presents an overall optimized predictive EMS for the Toyota Hybrid System (THS-II) power train of the Prius. The proposed EMS is based on Dynamic Programming (DP), where the prior knowledge of the route is required in order to predetermine the power-split ratio and optimize the fuel consumption for the whole predicted route. The DP EMS proposed for the THS-II power train is designed with a very short computation time, intended to be implemented in real-time applications. The potential of this DP-controller in reducing fuel consumption on regulatory cycles are computed and compared to a rule-based controller and to the Prius published fuel consumption results. Finally, the fuel reduction enhancements of the DP-controller are computed for real road tests achieved on a MY06 Prius in Ile-de-France, by comparing to the associated observed consumption measurements.

International audience; Distillation columns are one of the main methods used for separating air components. Their inconvenient is their high energy consumption. The distillation process is simulated in three types of columns and the exergy losses in the different parts calculated. A sensitivity analysis is realized in order to optimize the geometric and the operational parameters of each type of column. A comparative exergy analysis between the distillation columns considered for cryogenic air separation shows that the exergy efficiency of a double diabatic column, with heat transfer all through the length of the column, is 23% higher than that of the conventional adiabatic double columns.

International audience; This paper deals with the energy recovery in the dairy industry. Thermodynamic, economic and environmental optimization of three water-to-water heat pumps has been studied in order to replace totally or partially a fuel boiler used to produce heat at different temperature levels in a cheese factory. These heat pumps have their evaporators connected to one effluents source and two of them are equipped by storage tanks at the condenser side. Multi-objective optimization permits optimal repartition of mass flow rates of effluents and optimal choice of electrical power of the compressors and volumes of storage tanks. The thermodynamic objective is based on the exergy destruction in the whole system. The economic objective is based on the investment cost and the operating cost obtained with the heat pump system. The environmental impact objective has been defined and expressed in cost terms by considering a CO 2 taxation (carbon tax) on the GHG emissions. This objective has been integrated with the economic objective. Multi-objective genetic algorithms are used for Pareto approach optimization.

International audience; A new methodology of intermediate complexity level is developed to model the dry-expansion shell and U-tube evaporators. The model has a reasonable level of accuracy and uses fundamental physical principles in a distributed parameters approach capable of detecting the complex circuit of the shell-side flow. This level of details is necessary to simulate accurately the zeotropic refrigerant mixtures evaporation. Using Modelica language gives a heat exchanger model with a generic flow arrangement. The model is experimentally validated using a standard shell-and-tube evaporator working with HFC-134a. Three distinct working fluids, pure HFC-134a, R-407C, and a specially selected glide matching refrigerant mixture are simulated in the same heat source duty with different shell-and-tube configurations. Three different gas superheat values are also taken into account. The total amount of irreversibility is considered by calculating the total exergy losses. It is concluded that the effect of the temperature profile of any refrigerant mixture can be substantial on the relative performance of a particular heat exchanger configuration compared to counter-flow configuration.

International audience; This article describes a test method for measuring the burning velocity of flammable gases with air used as oxidant. Burning velocity is a physical property enabling the classification of flammable refrigerants. A safety standard committee, such as ASHRAE 34 SSPC, requests information about methods of tests capable of improving the classification of flammable refrigerants. The burning velocity is a function of the flammable gas concentration in the total mixture with air, and it can be measured at concentrations ranging from the lower propagation limit (LPL) of the flame in the tube to the upper propagation limit (UPL). The burning velocity reaches a maximum in the vicinity of the stoichiometric concentration. The test method is based on the initiation of the combustion of the gas, or blends of gases, in a homogenous mixture with air contained in a vertical cylindrical tube, and the observation and the recording of the flame propagation. Results for R-290, R-152a, R-717, R-32, and R-143a are presented using the tube method as described and performed at the Center for Energy and Processes.

Dry pressure drop in columns equipped with structured packings is considered to involve two components: drag force due to the direction changes near the column walls and in the transition region between two packing layers rotated to each other by 90°, and friction force between the different gas flows inside the crossing triangular channels and with the packing solid walls. It is believed that in a packed bed with compact sheet density and large packing surface area (above 250 m 2 /m 3 ), the major contribution of the pressure drop is generated by the friction component. In this paper, a model is proposed to determine the dry pressure drop friction component. The gas is assumed to establish a fully developed turbulent flow inside the structured packing channels. The structured packing geometry consists of a combination of periodic elements. It is shown that the reproduction of one periodic element aerodynamics leads to determine the gas distribution and pressure drop inside the packed bed. Therefore, modeling the dry pressure drop through one periodic element is a meaningful representation of the dry pressure drop over the packing. CFD simulations are carried out on periodic elements using different turbulence models: RNG k − e , realizable k − e , and SST k − ω . The best results that agree with the experimental data in the literature are obtained with the SST k − ω model. The CFD model proposed is used to study the impact of packing geometry variations on the dry pressure drop and to bring up a correlation for the pressure drop with respect to changes of packing geometry: channel height dimension, channel opening angle, and corrugation angle.

Online at stacks.iop.org/Met/47/135; International audience; Leak detection is widely used nowadays in various fields such as the automotive and refrigeration industries. The leak tightness of installations charged with refrigerants must be controlled periodically by refrigerant gas detectors, qualified by refrigerant leaks called reference leaks or 'calibrated' leaks. To this day, those refrigerant leaks are not traceable to the SI units under their operating conditions. Therefore, a project involving the LNE, the CEP and the ADEME was initiated in order to develop a national standard for calibrating refrigerant reference leaks. The method consists in measuring the accumulation of gas due to the refrigerant leak inside a closed volume at atmospheric pressure. The leak flow rate is deduced from the concentration variation, measured with a photo-acoustic spectrometer, the pressure and temperature in the accumulation volume and the capacity of the accumulation volume. The uncertainty budget thus takes into account the measurement uncertainties of these quantities. The main components of the uncertainty are due to the accumulation volume capacity and the measurement of concentration. The relative expanded uncertainty of leak flow rates between 1 g yr−1 and 50 g yr−1 is around 2%, depending on the value of the leak.

International audience; Great efforts have been made to date toward modeling nongray radiative heat transfer accurately. In this article, a new version of the plating algorithm, designated the re-plating algorithm, for total exchange areas (TEAs) calculation from direct exchange areas (DEAs) for nongray radiative problems is presented. The re-plating algorithm calculates TEAs for a given band number b from those of band number b - 1 by performing successive re-plating procedures. The effectiveness of the new algorithm is demonstrated for thermal modeling of an aluminum brazing furnace and a glass treatment furnace. CPU requirements for TEA calculation were reduced significantly.

International audience

Disponible en ligne contre 22$ à l'adresse : http://papers.sae.org/2009-01-1324ISBN: 978-0-7680-2131-8Product Code: SP-2235; International audience; Energy consumption and exhaust emissions are the most challenging issues in transportation that car makers and policy makers have to deal with. As a consequence, several technologies have been developed in order to limit fuel consumption and pollutant emissions. So far, some of the promising technologies for passenger cars are hybrid electric vehicles (HEV) and, later on, plug-in hybrid electric vehicles (PHEV). The study presents an assessment in terms of energy consumption and carbon dioxide emissions for gasoline HEV and PHEV compared to Internal Combustion Engine (ICE) conventional gasoline and diesel vehicles. This comparison intends to assess carbon dioxide and energy consumption reduction ability of PHEV for several countries or geographical region (EU 15, USA, Japan, and France). The energy consumption is computed with a detailed drive train model taking into account different driving patterns. The emissions are calculated depending on the electricity mix of the studied countries or group of countries. The study details the abatement potential of the new technology by geographical area. A detailed analysis of hourly carbon dioxide content of electricity is performed in order to study the impact of the electricity mix variation.

International audience; In order to study the low-temperature conductive drying of urban sewage sludge and evaluate its essential characteristics, a laboratory-scale drying device was set up. Sludge is modelled as a coarse aggregated, porous medium, and experiments are conducted to study its rheological behavior throughout a drying cycle and aggregation effects on diffusion. Investigations are based on a macroscopic model of sludge aggregates where only external porosity is accounted for This paper presents a method to evaluate water vapor diffusivity within urban sludge based on an analytical solution of a Fickian diffusive model which enables diffusivity determination by simple exponential regression over experimental data. Experiments are carried out with three levels of heating fluxes, 300, 525 and 700 W/m(2), without any remarkable effect of flux density on water vapor diffusivity over the tested range. Further experiments are conducted to underline the effect of mixing frequency. Predictive correlations for water vapor diffusivity as a function of sludge dry solid content and mixing frequency are reported in this work.

International audience

Session climate control (part 2 of 2) SP-2132,2007-01-1187; International audience

The new Prius hybrid vehicle uses an electrical scroll compressor which speed is controlled by an inverter. The control is integrated in the vehicle global control system. The paper presents the way to take into account the state of charge (SOC) of the batteries to run reproducible tests and in order that the battery charge is identical both at the end and at the beginning of the test. The vehicle fuel consumption has been analyzed with and without the air conditioning (AC) system running and for two different climatic conditions. Moreover tests have been carried out for the measurement of the electrical consumption of the AC system. Conclusions are drawn on the interest of electrical AC system compared to mechanical AC system for hybrid vehicles. The impact of the control system is also analysed and presented.

CD Rom

International audience; Six widely differing, novel capture processes, currently under development in Europe are described. These processes cover the range of postcombustion, precombustion and denitrogenation and show favourable possibilities for integration with power plants. They can be regarded as potential break-throughs in technical performance and/or costs.

Vol. SP-1973 paper 2005-01-1171