Biodiesel is formed by transesterification reaction of vegetable or animal fatty acid with alcohol. Agitation of fluid in the biodiesel reactor is required for occurring of the transesterification reaction. This research aims to study the flow behaviour in reactor with different type of agitator using computational fluid dynamics simulation and determine the optimum type of agitator in biodiesel production. Flow behaviour which was studied includes temperature and fraction distribution, turbulence intensity, and vorticity of fluid. The study was conducted in transient and steady state simulation with agitation types of helical screw, turbine, propeller, and anchor. The material that was modelled consist of cooking oil and methanol with mole ratio of 1:6. The mixing process used 500 rpm agitation speed and 60-65 oC mixing temperature. Furthermore, to determine the optimum agitator, the analytical hierarchy process method was carried out. The simulation results were analysed then obtained the score of each agitator, which were 0.314 (anchor), 0.350 (helical screw), 0.249 (propeller) and 0.087 (turbine). Based on the result, the optimum agitator was the helical screw type.
Kebutuhan energi di masyarakat saat ini terus meningkat seiring dengan terus bertambahnya jumlah penduduk. Sementara sumber energi utama saat ini, yaitu energi fosil terus mengalami penurunan produktivitas dan cadangan yang semakin menipis. Untuk mengatasi hal ini, maka pencarian berbagai alternatif energi baru yang terbarukan harus dilakukan. Salah satu sumber energi terbarukan yang cukup menjanjikan adalah biogas. Secara umum, biogas mengandung 60-65% gas metana (Harikishan, 2008), dimana jumlah kandungan metana ini adalah nilai yang cukup potensial untuk digunakan sebagai sumber energi alternatif. Selama ini biogas pada umumnya digunakan sebagai bahan bakar untuk untuk kompor memasak ataupun lampu penerangan.
To design a young coconut trimming machine, it's important to analyze the cutting mechanism of young coconut husk. The aim of this study were to analyze the cutting mechanism of young coconut husk and generate mathematical model of specific cutting force. Sharpening angle, cutting angle and sharpened knife were optimized to get the lowest cutting force. Mathematical model has been generated to estimate the maximum cutting force for one side sharpened knife and two side sharpened knife with cutting angle (θ) at 0 O and above 0 O. Based on the analysis of this study, the type of knife that require the lowest cutting force is two side sharpened knife with sharpening angle (β) = 10 O and cutting angle (θ)= 30 O .
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