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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]

Recycled ceramics made of inertized asbestos containing wastes have been submitted to high pressure/temperature cycling tests in the operating range of ACAES and CSP applications. Ten successive cycles between room conditions and 610 °C/30 bars for a cumulated duration of 2500 h lead to a validation of the ability of the material to resist to those constrains. The Wollastonite/Augite initial structure is gradually transformed in a unique Augite containing material. While mechanical parameters and density are unchanged, thermal capacity is reduced by 5% and thermal conductivity increased by 30%. This last result offers an advantageous way to enhance the thermal conductivity of those recycled ceramics, a key parameter to control the charge/discharge power in TES systems. [ABSTRACT FROM AUTHOR]

Selecting a heat transfer fluid (HTF) depends on the value of thermophysical parameters. In response to the need for innovative heat transfer fluids in concentrated solar power (CSP) plants, vegetable oil offers a promising solution. The relevant thermophysical properties are density, thermal conductivity and specific heat capacity. Moreover, a rheological property, the dynamic viscosity is also relevant. The objective of this work was to study and compare these properties for seven different vegetable oils (rapeseed, soybean, sunflower, palm, copra, cotton and jatropha) in the temperature range from ambient to 250 °C. For all the properties studied, the values evolved with increasing temperature and were influenced by the fatty acid composition of each vegetable oil. Experimental results are compared with those in the literature and are found to be consistent. The temperature dependencies are correlated to temperature using polynomial equations. The correlations presented here may be useful as a database for the selection of innovative heat transfer fluids. [ABSTRACT FROM AUTHOR]

Following the growing need for innovative heat transfer fluids in concentrated solar power (CSP) plants, the thermal conductivities of different vegetable oils (rapeseed, soybean, sunflower, palm, copra, cotton and jatropha) were measured in the temperature range from ambient to 230 °C relative to a reference oil. The small differences in the obtained thermal conductivities are influenced by the fatty acid composition. For balanced saturated/unsaturated fatty acids composition, the average thermal conductivity decreases from 0.167 W m −1 K −1 at 20 °C to 0.137 W m −1 K −1 at 230 °C. The use of a reference synthetic oil makes the calibration of the thermal probe unnecessary. The used method is based on a hot wire thermal probe with ac excitation and 3 ω lock-in detection and has a long-term relative error of 1.2% and absolute accuracy of 2%. It allows measuring in real-time, continuously and independently, the thermophysical properties of oils for thermal applications. [ABSTRACT FROM AUTHOR]