Master of Science in Biological and Agricultural Engineering (MSBAE)
Biological and Agricultural Engineering
The goal of this study was to design and test a pilot scale process for biodiesel production using advanced microwave technology and develop a numerical model for investigating various parameters affecting this process. Dielectric properties of materials play a major role in microwave design of a process. The dielectric properties (dielectric constant ε’ and dielectric loss ε”) of biodiesel precursors: soybean oil, alcohols and catalyst and their different mixtures were measured at four different temperatures (30°C, 45°C, 60°C and 75°C) and in the frequency range of 154 MHz to 4.5 GHz. Results indicate that the microwave dielectric properties of almost all components depend on both temperature and frequency. Addition of catalyst changed the properties of solvent due to the strong ionic nature. A scaled up version of a continuous microwave transesterification process was designed, built and tested. Experimental parameters were set based on previous laboratory scale results. Experiments were performed in a well controlled continuous pilot scale microwave reactor at temperatures of 60°C and 75°C and processing times of 5 to 15 minutes. Microwave power required to achieve the temperature of 60°C was 4000W and for 75°C was 4700W. Ethanol was used as a solvent with NaOH as a catalyst (< 0.2% by weight of oil). The conversion obtained was >99% for all experimental conditions. The final objective was to develop a basic numerical model of continuous electromagnetic heating of biodiesel precursors. A finite element model was built using COMSOL Multiphysics 4.2 software. High frequency electromagnetic problem was coupled with the non-isothermal flow problem. The model was tested for the two different power levels. The electric field, electromagnetic power flow and temperature profiles were studied. Resulting temperature profiles were verified by comparing to the experimental data. The presented study assists in understanding microwave heating application for biodiesel production. The dielectric property analysis gives a clear picture of interaction of biodiesel components with microwave irradiation, numerical model aids in understanding temperature distribution while experiments validate the results. This study can be applied to optimize the microwave assisted continuous biodiesel production process.
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Muley, Pranjali D., "Experimental and numerical investigation of pilot scale microwave assisted transesterification process for biodiesel production" (2012). LSU Master's Theses. 585.