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International audience; A detailed investigation of the physicochemical properties and thermal characteristics of argan fruit residues (AFRs) was carried out to identify their potential application as biofuels. This experimental study covered the four main by-products of argan fruit: argan pulp (AP), argan nut shell (ANS), argan oilcake (AOC) and argan deoiled cake (ADC). Physicochemical analysis was performed to characterize biomass-based materials. Thermogravimetric techniques (TG, DTG and DTA) were applied to assess structural decomposition, biomass reactivity and combustion parameters. Lastly, thermal conductivity and diffusivity between 25 and 100 °C were measured using the transient plane source technique (TPS). The study shows that heating values were in the range of 17–22.5 MJ kg−1, which is comparable to those of wood pellets and lignite coal. The maximum ash content was found in AP and the minimum in ANS. The residual oil of AOC was found to affect the drying process and calorific value. Thermal analysis showed that ANS has the highest ignition temperature and thermal conductivity values and therefore appears to be the most reactive material. Our data show that ANS has a good potential to produce heat through direct combustion. A pretreatment appears to be necessary to improve the characteristics of AP and AOC in order to make them suitable biofuels in the near future.

International audience; Argan shell is one of the main by-products during argan oil production. It is considered as an attractive, cheap and renewable biomass source for sustainable energy utilization. The present paper reports on combustion characteristics of argan shell in order to evaluate their potential for thermochemical conversion. Combustion studies using thermogravimetry (TG) are performed at four different heating rates of 5, 10, 15 and 20 degrees C.min(-1). Kinetic parameters under non-isothermal condition are calculated using FWO (Flynn-Wall-Ozawa method) and KAS (Kissinger-Akahira-Sunose) model free methods. From the results obtained, it was revealed that when the conversion level (alpha) fluctuates between 0.1 and 0.55, the average activation energy were 154 and 145 KJ/mol for FWO and KAS methods, respectively. Then, it decreases drastically with alpha >= 0.6, reflecting the kinetic complexity of the combustion process characterized by a faster reaction caused by the intense devolatilization stage. Overall, the results highlight the potential use of argan shell as a biomass product for thermal conversion through combustion.

This article reports on the effect of swirl intensity on the flow and combustion characteristics of pulverized olive waste (OW) burning. Numerical simulations are carried out using the computationa...

International audience; The paper describes a 3D numerical simulation of pulverized solid olive waste (OW) combustion in a vertical combustor. This study is developed, in order to design a new efficient burner which operates with olive waste as a biomass fuel. Two types of injection modes are studied. The first named (R) where the biomass particles is perpendicularly injected to symmetric axis close to the co-flow entry by four injection square shape tubes and the second named (P) where particles are injected in parallel to the furnace central axis. The mean diameter of the pulverized particles is about 70 µm. The designed system is a vertical cylindrical furnace with swirling co-flow burner entry. The k-ε, mixture fraction PDF and discrete phase DPM models are used for turbulence closure, turbulence-chemistry interactions and tracking the particle motion respectively. Results show that the flame is more stabilized in the recirculation zones and achieved the higher temperature at 1560 K for (R) case. The particles residence time inside to the combustor is very important for the (R) case in comparison to (P) case. The analyses and comparison of the formed species for CO, CO2 and NOx formation profiles at several longitudinal locations between (R) and (P) cases are performed.

The luminescence of Eu 2+ has been investigated in two families of BaF 2 -rich fluorohalides, Ba 12 Cl 5(1− x ) Br 5 x F 19 ( x ≤0.8) and Ba 7 Cl 2(1− x ) Br 2 x F 12 ( x ≤0.5). In the two kinds of host lattices, under UV excitation Eu 2+ shows an intense blue 5d→4f band emission at 300 K. At low temperature, in addition to the latter, 4f→4f lines are present in the near UV. The efficiency of the photostimulated luminescence (PSL) after X-ray irradiation has been measured and compared with that of BaXF:Eu (X=Cl, Br). High conversion efficiencies have been obtained with compositions Ba 12 Cl 5(1− x ) Br 5 x F 19 for stimulation at 532 nm. The presence of bromine is beneficial. For all compositions a high stimulation energy (SE) is needed to excite Eu 2+ ions through colour centres.