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Thermal Performances of a High Temperature Air Solar Ahsorber Based on Compact Heat Exchange Technology//! the framework of the Ft em h PEGASE project (Ptoditaion of Electricity h\ G As turbine attd Solar Energy), CNRSIPROMES laboratory is developing a 4 MWtli pressurized air solar receiver with a surface absorber based on a compact heat exchanger technology. The first step of this development consists in designing and testing a pilot scale (1110 scale, e.g., 360 kWth) solar receiver based on a metallic surface absorber. This paper briefly presents the hydraulic and thetmal performances of the innovative pressurized air solar absorber developed in a previous work. The goal is to be capable of preheating pressutized air from 350 °C at the inlet to 750 °C at the outlet, with a maximum pressure drop of 300 mbar. The receiver is a cavity of square apettute 120 cm x 120 cm and I m deepness with an average concentration in the aperture of more than 300. The square shaped apertme is chosen due to the small scale of the receiver: indeed, the performances are not enhanced that much with a round aperture, while the manufacturabilitv is much more complicated. However in the perspective of PEGASE, a tound aperture is likely to be used. The back of the cavity is covered by modules ananged in two series tnaking the modular and multistage absorber. The thetmal petformatices of one module are considered to simulate the thermal e.\change within the receiver and to estimate the energy efficietuy of this receiver. The results of the simulation show that the basic design yields an air outlet temperature of 739 °C under design operation conditiotis (1000 W/m' solar inadiation, O.H kgis airflow rate). Using the cavity walls as air preheating elements allows incteasing the air outlet temperature above 750 °C as well as the energy efficiency up to 81% hut at the cost of a critical absorber wall temperature. However, this wall temperature can be contt oiled by applying an aitnini; point .•strategy with the heliostat field.

Abstract:The European FP7 project HycycleS focuses on providing detailed solutions for the design of specific key components for sulphur-based thermochemical cycles for hydrogen production. The key components necessary for the high temperature part of those processes, the thermal decomposition of H 2 SO 4 , are a compact heat exchanger for SO 3 decomposition for operation by solar and nuclear heat, a receiver-reactor for solar H 2 SO 4 decomposition, and membranes as product separator and as promoter of the SO 3 decomposition. Silicon carbide has been identified as the preferred construction material. Its stability is tested at high temperature and in a highly corrosive atmosphere. Another focus is catalyst materials for the reduction of SO 3 . Requirement specifications were set up as basis for design and sizing of the intended prototypes. Rigs for corrosion tests, catalyst tests and selectivity of separation membranes have been designed, built and completed. Prototypes of the mentioned components have been designed and tested.Keywords: sulphur; catalyst; silicon carbide; membranes; thermochemical cycle.Reference to this paper should be made as follows: Roeb, M., Thomey, D., Graf, D., Sattler, C., Poitou, S., Pra, F., Tochon, P., Mansilla, C., Robin, J-C., Le Naour, F., Allen, R.W.K., Elder, R., Atkin, I., Karagiannakis, G., Agrafiotis, C., Konstandopoulos, A.G., Musella, M., Haehner, P., Giaconia, A., Sau, S., Tarquini, P., Haussener, S., Steinfeld, A., Martinez, S., Canadas, I., Orden, A., Ferrato, M., Hinkley, J., Lahoda, E. and Wong, B. (2011) 'HycycleS: a project on nuclear and solar hydrogen production by sulphur-based thermochemical cycles ', Int. J. Nuclear Hydrogen Production and Applications, Vol. 2, No. 3, Sabine Poitou studied Chemical Engineering at ENSIC (Ecole Nationale Supérieure des Industries Chimiques) in the National Polytechnic Institute of Lorraine (1991Lorraine ( -1994. Working at the CEA since 1998 as Research Engineer, she was involved on nuclear waste treatment and conditioning studies until 2007. Since 2008, her activity has concentrated on industrial development of hydrogen production with nuclear reactor coupled processes. George Karagiannakis received his PhD in Chem. Eng., at the Aristotle Univ. of Thessaloniki, Greece. He has been an Affiliated Researcher at APTL since 2006 and a member of the Nanoparticles and Catalysts Group. He has expertise in catalytic and electrocatalytic studies, with emphasis in those involving hydrogen productions. He has participated in several national and EU research projects.Christos Agrafiotis is a Principal Researcher at CPERI, Chemical Engineer. He received his PhD in Chem. Eng., from SUNY, Buffalο, USΑ. He has more than 15 years of expertise in powder synthesis and catalytic coating of monolithic reactors, participated in several EU-and nationally-funded research projects in these areas, and he is the author of more than 40 relevant publications in international journals and proceedings. Athanasios Konstandopoulos is the Director of APTL and C...

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The temperature and the temperature gradient within the battery pack of an electric vehicle have a strong effect on the life time of the battery cells. In the case of automotive applications, a battery thermal management (BTM) system is required to maintain the temperature of the cells within a prescribed and safe range, and to prevent excessively high thermal gradients within the battery pack. This work documents the assessment of a thermal management system for a battery pack for an electric van, which adopts a combination of active/passive solutions: the battery cells are arranged in a matrix or composite made of expanded graphite and a phase change material (PCM), which can be actively cooled by forced air convection. The thermal dissipation of the cells was predicted based on an equivalent circuit model of the cells (LG Chem MJ1) that was empirically calibrated in a previous study. It resulted that, in order to keep the temperature of the battery pack at or below 40 °C during certain charge/discharge cycles, a purely passive BTM would require a considerable amount of PCM material that would unacceptably increase the battery pack weight. Therefore, the passive solution was combined with an air cooling system that could be activated when necessary. To assess the resulting hybrid BTM concept, CFD simulations were performed and an experimental test setup was built to validate the simulations. In particular, PCM melting and solidification times, the thermal discrepancy among the cells and the melting/solidification temperatures were examined. The melting time experimentally observed was higher than that predicted by the CFD model, but this discrepancy was not observed during the solidification of the PCM. This deviation between the CFD model results and the experimental data during PCM melting can be attributed to the thermal losses occurring through the mock-up casing as the heating elements are in direct contact with the external walls of the casing. Moreover, the temperature range over which the PCM solidifies was 6 °C lower than that estimated in the numerical simulations. This occurs because the simple thermodynamic model cannot predict the metastable state of the liquid phase which occurs before the onset of PCM solidification. The mockup was also used to emulate the heat dissipation of the cells during a highway driving cycle of the eVan and the thermal management solution as designed. Results showed that for this mission of the vehicle and starting from an initial temperature of the cells of 40 °C, the battery pack temperature could be maintained below 40 °C over the entire mission by a cooling air flow at 2.5 m/s and at a temperature of 30 °C.

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Background: The thermal management of a battery pack designed for an electric vehicle is a key to prevent accidental events and ensure a long lifespan of the batteries. A typical accident is a thermal runaway of one or more cells in the battery which can cause fire or explosion of the battery pack. This paper presents a numerical modelling of a battery pack (BP) and its heat exchanger (HE) for an electric vehicle. The heat produced in the battery is evacuated by the HE. Methods: Two different kinds of modelling have been realized: a computational fluid dynamic (CFD) modelling and a coarse (called MOD3 for 3D Model) modelling. The CFD modelling allows the creation of fine numerical simulations of a BP, but uses large meshes, therefore the cost of each calculation is important. In order to make a large number of quite long transient simulations, a second tool called MOD3, employing only a coarse mesh, was developed in this study at the Commissariat à l’énergie atomique et aux énergies alternatives (CEA). Results: Two measurement campaigns corresponding to two different versions of the HE have been conducted at CEA. The temperature measurements allow comparisons of MOD3 to a real battery pack and to fit some heat exchange coefficients. The cells temperatures as well as the cooling liquid temperature are compared. Conclusions: The MOD3 tool has been fitted partly on CFD calculations, and partly on experimental measurements. It will be integrated in a machine learning environment by CIDETEC to take into account the thermal management of the BP in real car simulations.