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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.

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.

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; 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; 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.

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; 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.

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.

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.

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 Vol. SP-1946 paper 2005-01-1507

Vacuum insulated panels (VIP) is an emerging technology that may constitute an alternative to rigid polyurethane (RPU) foam as insulation in refrigerators and freezers. The VIP “skin effect” caused by the aluminum layer in the envelope complicates the evaluation of the global thermal resistance. This paper presents a new method of VIP characterization. Values of the global thermal resistance obtained are used in a dynamic simulation tool ENEREF® to perform predictive calculations. Direct experimental measurements permit to validate calculations. Finally, a life cycle cost analysis is performed and payback period of the technical option is calculated.

To encourage energy savings, measurement of energy consumptions shall be technically unquestionable and these measurements shall be published and advertised.

International audience; Air conditioning system (ACS) is one of the most important equipment to provide passengers climatic comfort. Energy consumed by the ACS is due to the compressor mechanical power and heat exchanger air fans electric power. A test bench for measuring these two series of power for a wide range operating conditions has been developed. The tests, made under various climatic conditions and vehicle speed profiles, measure power value and also highlight parameters which those power levels.

A numerical simulation model that predicts the thermal comfort in public transportation buses was developed. A precise approach based on the assembly of zonal and nodal models, coupled with CFD results obtained for stationary conditions, is used to simulate the thermal and air flow phenomena inside the passenger compartments. The model allows to determine the thermal (solar, passenger, and convective) loads of the bus and then to qualify the comfort level using the equivalent temperature. Simulations carried out show the influence of air distribution inside the bus on passenger’s thermal comfort.