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The ultrasound method is used to improve mass transfer between incompressible reactants which increases their chemical reaction and reduces reaction time as well as energy consumption. In this research, transesterification process variables of rice bran oil were optimized using response surface methodology (RSM). Three process parameters were investigated, namely methanol to oil molar ratio, catalyst concentration, and time. The optimum conditions of the transesterification process based on RSM were: (1) methanol to oil molar ratio: 1:6; (2) catalyst concentration: 0.5% wt.; and (3) time: 48 min, with methyl ester yield of 94.12 %. The optimum rice bran methyl ester yield predicted by RSM was validated by replicating three independent parameters with showed average rice bran methyl ester yield of 93.98%. The properties of the rice bran biodiesel properties were measured and the values met the requirements of the ASTM D6751 and EN 14214 standards.

Optimizing the process parameters of biodiesel production is the key to maximizing biodiesel yields. In this study, artificial neural network models integrated with ant colony optimization were developed to optimize the parameters of the two-step Cerbera manghas biodiesel production process: (1) esterification and (2) transesterification. The parameters of esterification and transesterification processes were optimized to minimize the acid value and maximize the C. manghas biodiesel yield, respectively. There was excellent agreement between the average experimental values and those predicted by the artificial neural network models, indicating their reliability. These models will be useful to predict the optimum process parameters, reducing the trial and error of conventional experimentation. The kinetic study was conducted to understand the mechanism of the transesterification process and, lastly, the model could measure the physicochemical properties of the C. manghas biodiesel.

Pada umumnya peralatan PLTBS di PT. Ukindo telah dirancang, dengan peralatan khusus dalam memproduksi listrik, seperti Engine gas dan generator agar keamanan serta keselamatan pekerjanya terjamin. Salah satunya Pabrik kelapa sawit sebagai penghasil energi listrik terbarukan, terlebih dalam bentuk limbah cair pks. Kinerja PKS Ukindo cukup bagus, dengan didapatkan kesetabilan TBS diolah selama lima tahun terakhir, dengan rata-rata mengolah diataston 300 TBS/tahun. Sebagian bahan baku TBS diperoleh dari pihak ketiga. Dari hasil analisis perhitungan maka diperoleh daya terbangkit 1,3 MW. Perhitungan ini menggunakan asumsi pada produksi terendah pada tahun 2014. Jika kemudian jumlah TBS diolah lebih besar, maka potensi daya yang dihasilkan jika akan lebih besar, sehingga analisis daya terpasang masih bisa meningkat.

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Lube oil cooler adalah cross flow compact heat exchanger yang berfungsi untuk melepaskan panas yang dibawa oleh minyak pelumas dialirkan melalui sisi shell menuju sisi tube dengan fluida pendingin air demin dimana masing-masing cairan dipisahkan di dalam lube oil cooler. PT. PLN Sektor Pembangkit Belawan merupakan salah satu unit pembangkit tenaga listrik di wilayah Sumatera Utara yang kinerja dan kehandalannya sangat penting untuk menjamin kelangsungan pasokan listrik. Dari penelitian ini, rasio koefisien perpindahan panas disisi shell dan pipa tube serta efektivitas perpindahan panas yang terjadi dapat diketahui dengan menganalisa temperatur masuk dan keluar aliran air pendingin dan minyak pelumas dapat ditentukan. Selain itu dampak dan penyebab penurunan kinerja lube oil cooler dapat diketahui. Penelitian ini berfokus pada analisis data temperatur masuk dan keluar pendingin minyak pelumas dan tekanan diferensial yang tercermin dari data operasional yang dikumpulkan dari ruang kontrol lembar kertas PLTU Belawan.

The depletion of fossil fuels, rising of earth temperatures and declining of air quality are an unavoidable phenomenon today. Bioethanol fuel is one solution to reduce this problem that comes from renewable raw materials. The purpose of this study is to investigate engine performance and exhaust emissions at gasoline engine by using the sorghum seeds bioethanol-pertalite blends with different mixed ratios (10%, 15%, and 20%). The test is performed on a four-stroke gasoline engine without modification. Engine speeds vary from 1000 to 4000 rpm, and properties of the sorghum seeds bioethanol-pertalite blends are measured and analyzed. In addition, engine torque, brake power, brake specific fuel consumption (BSFC) and brake thermal efficiency (BTE) as well as carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) emissions are measured. The results show that BSFC decreased while BTE increased for a fuel blends containing 20% bioethanol at 3500 rpm engine speed, with each maximum value of 246.93 g/kWh and 36.28%. It is also found that CO and HC emissions are lower for the sorghum seeds bioethanol-pertalite blends. Based on the research results, it can be concluded that the sorghum seeds bioethanol-pertalite blends can improve engine performance and reduce exhaust gas emissions. Keywords: bioethanol; pertalite; performance engine; exhaust gas emission; alternatif fuel.