Instead of simplified steady-state models, with modern computers, one can solve the complete aero-thermodynamics happening in gas turbine engines. In the present article, we describe a mathematical model and numerical procedure to represent the transient response of a PT6A gas turbine engine operating at off-design conditions. The aero-thermal model consists of a set of algebraic and ordinary differential equations that arise from the application of the mass, linear momentum, angular momentum and energy balances in each engine’s component. The solution code has been developed in Matlab-Simulink® using a block-oriented approach. Transient simulations of the PT6A engine start-up have been carried out by changing the original Jet-A1 fuel with biodiesel blends. Time plots of the main thermodynamic variables are shown, especially those regarding the structural integrity of the burner. Numerical results have been validated against reported experimental measurements and GasTurb® simulations. The computer model has been capable to predict acceptable fuel blends, such that the real PT6A engine can be substituted to avoid the risk of damaging it.

The potential of sawmill wastes as a raw material in pyrolysis process is presented in this study. Non-isothermal thermogravimetric analysis (TGA and DTG) and isoconversional methods were employed to determine triplet kinetic (activation energy, reaction model and pre-exponential factor). Through TGA and DTG, the conversion degree is described as a function of temperature for five heating rates (10, 20, 30, 40 and 50o C/min) and four model-free methods (Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Friedman, and Vyazovkin) with temperatures ranging from 25 to 1000°C were employed. Isoconversional lines were built for every method at different isoconversional degrees α∈true[0,1true]. The activation energy E was found as a function of α in the interval χII=true[0.2,0.7true] where each isoconversional methods were in agreement and the estimated error was sufficiently small. Findings show the same activation energy profile independently of the isoconversional method. In particular the total variation of E in χII was as follows: 209.909–228.238 kJ/mol (FWO); 211.235–229.277 kJ/mol (KAS); 223.050–188.512 kJ/mol (Friedman), and 211.449 kJ/mol-229.512 kJ/mol (Vyazovkin). The reaction model of the process in χII matched with a two-dimensional diffusion (D2) by using a master-plot analysis. The calculated and reported parameters are fundamental information for the pyrolysis reactor design using Sawmill wastes as feedstock.

In the aviation sector, the use of biofuels has increased worldwide, therefore, this study assesses the environmental impact of these mass-based blends, named BK0, BK10, BK20 and BK30, according to their composition (Biodiesel + Kerosene) and the percentage of mass fraction. The study uses life cycle analysis with the SimaPro software and the Ecoinvent database for Colombia. The stages of cultivation, oil extraction and refining were established for biodiesel, while for the kerosene the stages defined were crude oil extraction and its refining. Results show that the stage with the greatest impact is the cultivation and extraction for both the category of freshwater ecotoxicity, acidification and terrestrial eutrophication.keywords: Biodiesel, Freshwater Ecotoxicity, Acidification, Terrestrial Eutrophication, Life Cycle. RESUMEN.En el sector de la aviación, el uso de biocombustibles se ha incrementado a nivel mundial, por lo tanto, se evaluará el impacto ambiental de estas mezclas con base másica, llamadas BK0, BK10, BK20 y BK30 de acuerdo con su composición (Biodiesel + queroseno) y con el porcentaje de fracción másica presente. El estudio utiliza análisis de ciclo de vida con el software SimaPro y la base de datos Ecoinvent para Colombia. Se establecieron para el biodiesel las etapas de cultivo, extracción de aceite y refinación, para el queroseno se definieron las etapas de extracción del crudo y su refinación. Se evidencia que la etapa que mayor presenta impacto es el cultivo y la extracción tanto para la categoría de ecotoxicidad de agua dulce, acidificación y eutrofización terrestre.Palabras clave: biodiesel, ecotoxicidad de agua dulce, acidificación, eutrofización terrestre, ciclo de vida.