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Abstract: Composite materials made of expanded natural graphite (ENG) matrix in which activated carbon has been elaborated, present high thermal conductivity (up to 30Wm−1 K−1) compared to conventional activated carbon bed (0.15–0.5Wm−1 K−1). In a first part [D. Menard, X. Py, N. Mazet, Activated carbon monolith of high thermal conductivity for adsorption processes improvement. Part A. Adsorption step, Chem. Eng. Process., 44 (2005) 1029–1038], the experimental adsorption of pure and diluted CO2 has been presented for both the composite and a commercial granular bed for comparison. In the present part, thermal regenerations of the two adsorptive beds by peripheral heating are presented. The conductive composite leads to reduced regeneration time and to the production of concentrated gaseous streams of the adsorbate. The experimental data have been used for numerical model validation which is used for the estimation of the materials performances in larger column scale. [Copyright &y& Elsevier]

Abstract: Due to the low thermal conductivity of conventional beds of granular adsorbents (0.15–0.5Wm−1 K−1), performances of gas separation as well as gas storage processes are usually strongly inhibited by the induced adsorptive thermal effects. A monolithic composite of intensified overall thermal conductivity (10Wm−1 K−1), made of activated carbon (AC) in situ elaborated within a consolidated expanded natural graphite (CENG) matrix has been experimentally tested under both conditions of non-isothermal and non-adiabatic CO2 adsorption. Heat transfer intensification and process performances improvements for the conventional saturation step is described in terms of induced local temperature increases, adsorbate breakthrough and sorption capacity. Experimental conductive packing achievements are compared to those of a conventional packed bed of commercial TA70 granular activated carbon. [Copyright &y& Elsevier]

A new highly thermally conductive composite material made of activated carbon in-situ activated within a consolidated expanded natural graphite (CENG) matrix is developed in the specific case of gas separation processes. According to the particular chosen testing case of CO2/N2 mixture, the microporous characteristics of the adsorbent fraction have been selected and the various properties of the whole material studied. Activated carbon effective densities, overall thermal conductivities and external heat transfer coefficients up to 650 kg×m−3, 32 W×m−1×K−1 and 3000 W×m−2×K−1 were obtained, respectively. Two macroscopic external shapes were realized, namely a corrugated-sheets static mixer and a multi-axial-diffuser cylindrical monolith which will be further tested in a pilot equipment for comparison with conventional adsorbents. [Copyright &y& Elsevier]

New thermal storage composites made of graphite and PCM (NaNO3/KNO3 eutectic) have been developed for solar thermal power plants using direct solar steam generation. Those materials, obtained using different elaboration routes (compounding, infiltration, cold compression) and graphite types, are presented with their respective properties (enhanced thermal conductivities, thermal storage capacities, stability) and compared together. Both the laboratory and industrial scales and grades are considered and compared. The infiltration route has been found to be inefficient before the two other ones. Compound composites present isotropic properties and thermal conductivity intensification in the medium range (a factor of 10 for 7 wt % in graphite). Cold compressed composites present highly anisotropic properties and strong intensification in thermal conductivity (a factor of 31 at 200°C for 20 wt % in graphite). Their melting and solidification temperatures as well as their intrinsic storage capacity are close to the pure salt ones. [ABSTRACT FROM AUTHOR]

Abstract: This work aims to evaluate the performance of a solar domestic hot water (SDHW) system including a latent storage material. The originality of our approach consists to place a composite made of compressed expanded natural graphite (CENG) and phase change material (PCM) directly inside a flat plate solar collector in order to replace the traditional copper-based solar absorber. According to this target, the study is composed of two steps: the composites preparation and characterization; and the analysis of the system to achieve optimal integration of the material in the process. The present paper is focused on the selection of the most promising composite to implement in the solar collector. In order to reach this objective, several composites based on CENG and various storage materials (paraffin, stearic acid, sodium acetate trihydrate and pentaglycerin) have been elaborated and characterized. The synthesis of all these measurements allowed us to select three composites whose characteristics match their integration into a solar thermal collector. [Copyright &y& Elsevier]

Abstract: The overall objective of this work is to evaluate the potential of compressed expanded natural graphite (CENG) and phase change material (PCM) composites to improve the performance of solar domestic hot water (SDHW) systems. To achieve this target, an original approach has been chosen. Comparatively to other studies, in which the storage material is usually placed on top of the water tank, the proposed approach was to place the composite directly inside a flat plate solar collector in substitution to the traditional copper-based solar absorber. In a previous paper (), elaboration and characterization of various composites led to the selection of three relevant composites suitable to their integration into a solar thermal collector. The present paper is devoted to the analysis of such a system to evaluate its actual performance. To reach this objective, a numerical model is proposed and its reliability validated by mean of corresponding experimental data. Despite the fact that under summer meteorological conditions the performed simulation highlights an increase of the system efficiency by adding a composite to the solar collector, the cumulative annual performance of such a system is penalized by low efficiency during winter time. However, the obtained simulated results allow us to offer a perspective of work that would maximize the benefits of adding storage composite to a SDHW system. [Copyright &y& Elsevier]