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dc.contributor.advisorColucci Ríos, José
dc.contributor.authorAlpe Benítez, Fabio
dc.date.accessioned2019-03-01T12:09:58Z
dc.date.available2019-03-01T12:09:58Z
dc.date.issued2004
dc.identifier.urihttps://hdl.handle.net/20.500.11801/1815
dc.description.abstractExperiments of biodiesel production via methanolysis were performed at methanol/triglyceride molar ratios of 3, 4.5, and 6 and temperatures of 25 ºC, 40 ºC and 60 ºC; the reaction was monitored by HPLC, X-Ray, and GC-MS until equilibrium. A mathematical model called CAVITATION MODEL was developed to deal with mass transfer aspects of the alkaline transesterification reaction of vegetable oils; a comparison between the cavitation model and diffusion through spherical pores was made. Gas-vapor bubble dynamics for the methanol-soybean oil and methanol-tallow system were examined at 40 ºC and 42 ºC, respectively. The Rayleight-Plesset equations were used to describe the isothermal growth and adiabatic collapse of the bubble formed when a field of ultrasound at 20 KHz is applied. Temperatures of 2265 K and 426 K were estimated for a bubble in soybean oil-methanol and tallow-methanol systems, respectively. These “Hot Spots” could be responsible for the increment of the temperature occurred and the acoustic streaming observed during the alkaline transesterification reaction. Also, a diffusion analysis with the pore model was made to predict the concentration profile of the triglycerides within the liquid drops of alcohol created after the collapse of the gas-vapor bubbles; spherical shapes were studied. A computational model was made in MathCad to evaluate the effectiveness at different Thiele modulus values in order to estimate mass transfer coefficients for the most critical conditions of pure diffusion and these coefficients were compared with those found by the cavitation model estimation. Pictures of the reactant system soybean oilmethanol-potassium hydroxide, with the red dyed methanol using phenolphthalein, showed that the alkalinity of the system represented by potassium hydroxide remains in the interface alcohol-oil and then is displaced into the glycerol or down layer. The present study serves as a basis for the analysis of heterogeneous reactions with immiscible liquids using ultrasonic agitation.en_US
dc.description.abstractEn este estudio se realizaron experimentos de producción de biodiesel via metanólisis considerando relaciones molares de metanol/triglicérido de 3, 4.5, y 6; y temperaturas de 25 ºC, 40 ºC y 60 ºC. La reacción fue observada hasta equilibrio por cromatografía líquida, cromatografía gaseosa y fluorescencia de rayos X. Para analizar aspectos de transferencia de masa usando ultrasonido como medio de agitación se desarrolló un modelo matemático llamado “CAVITATION MODEL”, el cual se comparó con el modelo de difusión de poros esféricos. La dinámica de estos sistemas de burbujas gas-vapor, conteniendo metanol-aceite de soya y metanol-cebo sometidos a frecuencias ultrasónicas de 20 KHz y potencias aplicadas alrededor de 30 W, se examinó mediante la solución de las ecuaciones de Rayleight-Plesset usando un programa desarrollado en MathCad. El primer sistema mencionado se evaluó a 40 ºC y el segundo a 42 ºC de temperatura global, encontrándose temperaturas locales de colapso de burbuja de 2265 K y 426 K para el sistema aceite de soya-metanol y el sistema cebo-metanol, respectivamente. Se cree que estas condiciones de colapso son en gran parte las responsables del rápido incremento de temperatura observado durante la reacción catalizada tanto por hidróxido de potasio como por la agitación acústica presente. Usando un programa desarrollado en MathCad se pudo además estimar el coeficiente de transferencia de masa para el triglicérido en metanol. El criterio que se usó para discernir sobre el paso controlante de la reacción incorporó el nuevo modelo de cavitación y el modelo de poros esféricos, creando así una base para realizar este tipo de análisis en reacciones donde los reactivos son líquidos inmiscibles y se usa agitación ultrasónica.en_US
dc.description.sponsorshipLaboratory NREL-DOE.en_US
dc.language.isoenen_US
dc.subjectUltrasonic wavesen_US
dc.subjectTransesterificationen_US
dc.subject.lcshBiodiesel fuelsen_US
dc.subject.lcshTransesterificationen_US
dc.subject.lcshUltrasonic wavesen_US
dc.subject.lcshTallowen_US
dc.subject.lcshCavitationen_US
dc.subject.lcshVegetable oils as fuelen_US
dc.titleEffects of the use of ultrasonic waves on biodiesel production in alkaline transesterification of bleached tallow and vegetable oils: Cavitation modelen_US
dc.typeDissertationen_US
dc.rights.licenseAll rights reserveden_US
dc.rights.holder(c) 2004 Fabio Alape Benítezen_US
dc.contributor.committeeNegrón, Edna
dc.contributor.committeeSuleiman, David
dc.contributor.committeePortnoy, Arturo
dc.contributor.representativeRiquelme, Ernesto
thesis.degree.levelPh.D.en_US
thesis.degree.disciplineChemical Engineeringen_US
dc.contributor.collegeCollege of Engineeringen_US
dc.contributor.departmentDepartment of Chemical Engineeringen_US
dc.description.graduationYear2004en_US


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