The thermal degradation of different wood biofuels collected in the Arkhangelsk region (northwest of the Russian Federation) was investigated in order to extract their kinetic parameters. Thermogravimetric analysis was carried out for small samples under inert atmosphere or air. These samples were heated from 20 to 1300°C under three heating rates of 5, 10 or 20°C min -1 . The mass loss rates were measured during the drying, devolatilization and char combustion processes. Average values of the activation energies were determined using Friedman's and OzawaFlynn-Wall's methods under inert atmosphere and air. The morphological analysis of raw samples and of the corresponding chars was also performed. Pore development presents an effective impact on char reactivity. These experimental results and the kinetic data obtained in this work should be considered for the simulation of the pyrolysis and combustion processes of different biofuels in industrial devices.Keywords Wood biofuel Á Pyrolysis Á Thermogravimetric analysis under inert atmosphere or air Á Morphological analysis Á Kinetic analysis of thermal degradation
List of symbols aConversion rate of biofuel m(0) Initial mass of the sample (kg) m(t) Sample mass at time t (kg) m f Sample mass after the thermal decomposition of biofuels (kg) kKinetic constant (s -1 ) k 0Pre-exponential factor (s -1 ) E Activation energy (J mol -1 ) N Reaction order R Ideal gas constant (J mol -1 K -1 ) T Temperature (K)
This paper describes a case study of wind resource assessment and wind park design at Solovetsky Islands, which are located in the Arctic region of northern Russia. The Solovetsky historical and cultural complex has been included in the list of UNESCO's World Heritage Sites. 18 year's data of wind climatology from the NASA Langley Research Center (LaRC) is used for wind resource assessment at Solovetsky Islands for two different wind park locations. Computational Fluid Dynamics (CFD) based numerical simulations are carried out for wind resource assessment and for the estimation of the resultant Annual Energy Production (AEP) for both locations. To better understand wind flow physics and effects of wind turbine wake effects, three different wake models are used for the numerical simulations. Analyses of seasonal weather effects on energy production show that wind power production at Solovetsky Islands is higher during winter period as compared to summer period, mainly due to higher wind speeds and air density at cold winter conditions. A preliminary case study about wind park layout optimization has also been carried out, where results show an increase in AEP with the optimization of wind park layout.
This paper presents a study of the impact of icing on the performance of a pitch-regulated large wind turbine. Numerical simulations of six blade sections of the NREL 5 MW wind turbine at various free stream velocities are performed. Blade Element Momentum (BEM) method along Computational Fluid Dynamics (CFD) bases multiphase numerical simulations are used for this study. Analysis shows that the simulated parameters are in good agreement with the real conditions for each blade element during operation, except for the three-dimensional effects. The analysis of accreted ice shapes and air/droplet flow fields around the blade profile sections was carried out, and the calculation of aerodynamic performance, and energy production degradation was also performed. The tip of the blade is most affected by icing, it is characterized by the greatest changes in the aerodynamic performance. Maximum reduction in the wind turbine performance is estimated to be around 24%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.