monash_110827.pdf (15.26 MB)
Download fileExperimental and numerical investigation of a static mixer for the production of biodiesel
thesis
posted on 2017-05-15, 04:29 authored by Leong, Jason Yu ChuanCurrently, unless aided by subsidies or some form of government directive, biodiesel cannot compete against regular petro diesel because of lower pump costs.
Attempting to lower production costs of biodiesel would be helpful in narrowing the price gap between these two competing fuels. The production of biodiesel involves
mixing organic oil and a short chain alcohol which are not miscible in the early stages of reaction. The interfacial area
between the two phases is believed to strongly affect the reaction rate leading to the development of numerous methods for the dispersion of short chain alcohol in organic
oil. One such method is through the use of a static mixer which is a motionless inline pipe mixer with specially shaped baffles used to promote mixing.
This study investigated the effectiveness of a Kenics static mixer as a dispersion tool in biodiesel production with methanol as the short chain alcohol and palm oil as the
organic oil. This was performed by measuring the droplet sizes of methanol dispersed in palm oil for different flow parameters, namely the mixer length and flow rate. The
moderately high concentration of methanol (20% volume fraction) presented an additional level of complexity in the
experimental investigation and necessitated the development of a suitable droplet measurement technique which consisted of a modified borescope attached to a digital camera and coupled with a strobe light source.
Experimental results showed that the static mixer was certainly an effective mixer, outperforming the conventional agitated vessel design seen in most biodiesel
production plants but was not as effective as ultrasonic emulsifiers although this method requires the highest energy input.
The experimental study was complemented by a parallel numerical investigation which was performed using the commercial computational fluid dynamics (CFD) code ANSYS-FLUENT. To account for the droplet size evolution, the CFD simulations were coupled to a population balance model with the appropriate droplet
breakage and coalescence models. There was reasonable agreement between experimental results and numerical simulations. In addition, numerical simulations predicted
that the static mixer was the most efficient mixer when accounting both droplet size reduction and energy requirements.
The findings of this study suggest that the Kenics static mixer is an efficient mixer. It is, therefore, worth investigating the use of the Kenics static mixer as a
continuous reactor for the production of biodiesel without any rotating parts and possibly at room temperature. This
would present a novel design which could be attractive in achieving quality product at low operating cost.
History
Campus location
AustraliaPrincipal supervisor
Boon Thong TanYear of Award
2013Department, School or Centre
Sunway Campus. Faculty of Engineering. School of Engineering. Department of Mechanical EngineeringCourse
Doctor of PhilosophyDegree Type
DOCTORATEFaculty
Faculty of EngineeringUsage metrics
Categories
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Computational fluid dynamicsOpen accessOptical measurementDroplet coalescenceMultiphase simulationBiodiesel1959.1/797585Droplet size evolutionethesis-20130304-09054High speed droplet visualisationPopulation balance modellingNumerical simulationStatic mixersmonash:110827thesis(doctorate)Droplet breakage2013Dispersed phase system