A SOLSTICE Labex PhD student, Kuo Zeng, has won 2016 National Excellent Self-funded Oversea Students scholarship program. He was selected among 13 candidates in France and 500 candidates worldwide.
A ceremony is organized on 11 March 2017 in Chinese Embassy in Paris.
Kuo Zeng has prepared his PhD on solar biomass pyrolysis in the framework of a collaboration between PROMES and RAPSODEE (France). The model was developed in collaboration with the Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET - UNCo), 1400 Buenos Aires St., 8300 Neuquén, Argentina.
Abstract of the PhD thesis
Concentrated solar energy provides heat to drive biomass pyrolysis reactions that upgrades the feedstock energy by storing solar energy in chemical forms (bio-gas, bio-oil and bio-char). Thanks to high temperature and fast heating rate, more pyrolytic gas with high lower heating value (LHV) can be produced by direct solar pyrolysis.
Experiments have highlighted the effect of solar pyrolysis parameters on products yields, composition and properties. The temperature drastically affects the final product distribution and gas composition. It is the key parameter governing solar pyrolysis reactions. The heating rate and argon flow rate also have a significant influence. These three parameters affect intra-particle and extra-particle tar reactions, which determine the final product distribution. By contrast, the pressure has minimal influence on the product distribution. The total gas LHV dramatically increases (5-fold) with increasing temperature (from 600°C to 1200°C) and sample heating rate (from 5°C/s to 50°C/s), which is mainly due to variations in the CO and H2 yields. The interaction between temperature and heating rate enhances at both high ranges. The maximum gas products LHV (14 589 kJ/kg of beech wood) was obtained at 2000°C and 450°C/s heating rate. The collected char and tar were analyzed and characterized that emphasizes the temperature and heating rate effects. The energy upgrade factor was finally determined in the range 1.2-1.5 as a function of tar water content.
At the same time, a 2D unsteady CFD particle model (simplified assumption using first-order Arrhenius type reactions) with heat and mass transfers was developed for solar pyrolysis. Numerical model predictions were in good agreement with experimental observations. Stoichiometric coefficients about the mass fraction of primary tar converted by the reaction to gas and secondary tar were determined at different temperatures and heating rates for the first time.