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"The mathematical model was selected and the empirical equations were formulated from laboratory measurement by disturbed soil that was applied in undisturbed soil or field so required a correction factor. The correction factor could be expressed as a value of channeling fraction. The channeling process will affect to the average velocity of soil solution flow in soil. The average velocity of soil solution flows in soil controlled the fate of pesticide in undisturbed soil. The soil solution flows at undisturbed soil were expressed as two difference velocity values. The first part has equal velocity as its superficial velocity. The second part, because of chanelling, it was arbitrarily determined to be 10 times of the superficial velocity, and therefore, the superficial velocity of soil solution in the undisturbed soil must be corrected by the channeling fraction. The objective of the verification experiment was to identify a correction factor that could be expressed as channeling fraction in the equation as follows:V undisturbed soil = (1-channeling fraction) V Superficial + chanelling fraction (10 x v superficial)The verification was carried out at undisturbed soil obtained from three locations. The undisturbed soil in PVC pipe was saturated with water. After a saturated condition is reached, the flow direction of water was turned from top to bottom. The water continuously flows. After the steady state condition, water flow were substituted with the flow of fenitrothion solution, at the time was regarded as an initial condition (t=0). At the certain time the soil solutions at the outlet were taken to be determined the concentration of fenitrothion by HPLC. Based on the selected mathematical model and theempiricial equitations, the concentration of pesticide in soil solution as a position and time function can be calculated. The correction factor or the channeling fraction could be evaluated by comparing the fenitrothion concentration as a time function, from laboratory experiment data and from mathematical simulation result. The obtained channeling fraction values are 0.03, 0.05, and 0.1 for the clay loam-clay, the sandy loam-sand, and the loam-sandy loam textures, respectively."

"Reaktor plasma dengan konfigurasi umpan 3-lewatan untuk konversi gas CO2 dan CH4 perlu dimodelkan agar dapat merepresentasikan fenomena fisika dan kimia yang terjadi dalam reaktor. Pemodelan ini juga bertujuan mendapatkan kinerja reaktor yang diinginkan agar bisa digunakan sebagai dasar scale-up. Model reaktor disimulasikan dalam tiga dimensi menggunakan COMSOL Multiphysics dengan melihat pengaruh variasi laju alir umpan, temperatur di dalam reaktor, serta rasio mol umpan terhadap konversi dan produk syngas yang dihasilkan. Konversi tertinggi dicapai pada laju alir 4,6 mL/ menit dengan konversi CO2 sebesar 22% dan konversi CH4 sebesar 88,4% dengan rasio syngas yang dihasilkan CO2: CH4 = 1:1,14. Konversi yang dihasilkan tidak mengalami perubahan yang signifikan dengan naik atau turunnya temperatur di dalam reaktor. Dari variasi rasio mol umpan, konsentrasi CO yang dihasilkan meningkat sebanding dengan naiknya konsentrasi umpan CO2. Konsentrasi H2 yang dihasilkan meningkat sebanding dengan naiknya konsentrasi umpan CH4.

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Plasma reactor with 3-pass flow configuration for conversion CO2 and CH4 gas needs to be modeled in order to represent the physical and chemical phenomena that occur in the reactor. This modeling also aims to obtain the desired performance of the reactor to be used as the basis for scale-up. Reactor modeled in three dimensions using COMSOL Multiphysics to see the effect of the feed flow rate variations, the temperature inside the reactor, as well as the mole ratio of the feed to the conversion and syngas produced. The highest conversion achieved at a flow rate 4.6 mL/min, respectively the conversion of CO2 and CH4 is 22% and 88.4% with a ratio syngas produced CO2: CH4 = 1: 1.14. The conversion in the reactor did not change significantly with the increase or decrease the temperature in the reactor. The concentration of CO produced increase with increasing inflow concentration of CO2. The concentration of H2 produced increase with increasing inflow concentration of CH4."

"Penelitian ini membandingkan karakteristik pengabutan dan pembakaran dari campuran minyak nabati dan bahan bakar minyak pada setiap rasio pencampuran nya. Semburan nyala api pada pembakaran yang beroperasi pada tekanan 0,2 hingga 1,2 bar diamati secara optis. Bahan bakar nabati (BBN) memiliki kekentalan (viskositas) yang besar sehingga menjadi kendala dalam proses pembakaran. Karena itu untuk menurunkan viskositas nya perlu dicampur dengan bahan bakar minyak (BBM). Pembakaran yang baik memerlukan proses pengabutan yang baik. Pada penelitian ini proses pengabutan nya menggunakan nosel jet. Pengukuran kualitas pengabutan dan pembakaran dilakukan dengan metode fotografi dan perangkat lunak pemrosesan citra. Hasilnya menunjukkan bahwa rasio campuran BBN dan BBM yang terbaik adalah 40% : 60% untuk semua jenis campuran (minyak jelantah dan solar, minyak curah dan solar, minyak nyamplung dan solar serta minyak curah dan minyak tanah) dan tekanan operasi terbaik adalah 1,2 bar. Pada kondisi tersebut, campuran minyak curah dan minyak solar memiliki rerata suhu nyala yang paling tinggi (391,6oF) dan distribusi partikel aerosol terkecil yang paling tinggi (73%) meskipun masih di bawah BBM murni (100%).

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The spray atomization and combustion characteristic of vegetable oil and fosil fuel are compared to those ratio of mixtures on this paper. The spray flame was contained in an optically accessible combustor which operated at 0,2 - 1,2 bar of air pressure. Vegetable Fuel (VF) contains high viscosity that has been a, constraint in the combustion process; it needs to be mixed with Fosil Fuel (FF) in order to decrease the VF viscosity. A fine atomization process is necessary to fix the combustion. Research of atomization process was tested by using nozzle jet. The atomization and combustion quality were investigate by photographic method and image processing software was used to measure the spray droplet size. As a testing result, ratio mixture of 40% : 60% of VF and FF was good ratio mixtures ( used cooking oil diesel oil, cooking oil and diesel oil, nyamplung oil and diesel fuel, cooking oil and kerosene) compared to others ratio which operated at 1,2 bar of air pressure implying flame temperature. The flame temperatur of cooking oil and diesel oil mixture reached (391,6oF) as the highest mean temperature and distribution of aerosol particle reached (73%) although produced lower than fosil fuel (100%)."