Judul: Uji Karakteristik Minyak Nyamplung dan Aplikasinya Pada Kompor Tekan
Abstrak: In a rural area, tamanu oil is potential to produce energy which is able to replace kerosene as fuel in a pressure stove. To replace kerosene, tamanu oil must meet the likely criterias with kerosene. One of the most important criterias is in the matter of viscosity. Tamanu oil has higher viscosity than kerosene. Heating was done to decrease the viscosity of Tamanu oil. One of many ways to determine that the viscosity criteria of tamanu oil has been nearly equal to the viscosity of kerosene is by studying spraying criteria of tamanu oil. The purpose of this research was to determine and analyze the spraying criteria of tamanu oil in a pressure stove. This research also tested modified burner designed by Lestari (2011). Spraying testing was done by giving a treatment to tamanu oil in a certain temperature. From the testing result, tamanu oil had the nearly equal characteristic with the spraying kerosene when the temperature of tamanu oil reached ± 150oC. In this temperature, diameter and spraying angle of tamanu oil was 65,67 mm and 12.40o. Whereas, diameter and spraying angle of kerosene without heating treatment was 66,75 mm and 12.60o. According to Lestari (2011), heating must be done until the temperature of tamanu oil reached ±161.81oC, so that the viscosity of tamanu oil reached 5 cP or equal with the kerosene. From the result of the modified burner testing, apparently burner in a pressure stove could heat tamanu oil to reach 164.7oC temperature. Thus, we could conclude that modified burner in a pressure stove can decrease the viscosity of tamanu oil to reach a nearly equal with kerosene.
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Judul: Uji Daya Tahan Motor Bakar Diesel Berbahan Bakar Minyak Nyamplung (Calophyllum inophyllum L.)
Abstrak: Tamanu oil is one of alternative fuel for diesel engine which has close characteristics to diesel fuel. However, the viscosity of tamanu oil is much higher than petroleum diesel fuel, so it is necessary to lower down its viscosity for better atomization in fuel injection to get better combustion process. From previous research, diesel engine can operate well with pre-heated tamanu oil fuel in a short period. The objective of this study was to test the endurance of diesel engine with tamanu oil as its fuel. After endurance test, carbon deposit in engine component and lubricating oil quality were analyzed. An 8 HP diesel engine mounted to an electric generator and operated using tamanu oil for 50 hours with 2 kW load. The results showed that component of diesel engine such as piston, cylinder head, and injector still work well and seems normally. Specific fuel consumption for petroleum diesel fuel was 0.34 l/HP/hour and for tamanu oil fuel was 0.44 l/HP/hour. The weight of carbon on the diesel engine components when using tamanu oil fuel was 23.51% lower than using petroleum diesel fuel. The viscosity, total base number (TBN), and sulfated ash content of lubricating oil after 50 hours operation were 13.93 cSt, 1.063 mg KOH/g, 1.19 %weight for petroleum diesel fuel, and 15.57 cSt, 1.258 mg KOH/g, 1.42 %weight for tamanu oil fuel. The analysis of metal content showed that tamanu oil fuel resulted higher friction and wear, due to metal content of Fe, Cu, and Al exceed the maximum standard. FTIR (Fourier Transform Infra Red) analysis showed that soot content, oxidation, nitration, and sulfation of lubricating oil when using tamanu oil fuel are higher than using petroleum diesel fuel, but still below the allowable standard limit. It shows that lubricating oil contamination from fuel and combustion process residu when using tamanu oil fuel are higher than using petroleum diesel fuel. Regression analysis of lubricating oil properties shows that lubricating oil when using tamanu oil fuel have shorter life than using petroleum diesel fuel.
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Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. Suatu graf lengkap berorder 𝑛������ ≥ 3 dan graf r-regular berorder 𝑛������ ≤ 2𝑟������ + 1 merupakan graf Hamilton, Karena kedua graf tersebut memuat cycle Hamilton. Selanjutnya, syarat cukup tersebut digunakan untuk menentukan keberadaan cycle Hamilton pada graf 2-connected 4- regular berorder kurang dari 10.
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular