Gasification is a potential technology to convert municipal solid waste into energy in the form of syngas. Addition of air to the pyrolysis zone and oxidation was carried out by modifying a single-stage downdraft gasifier into a multistage air inlet. The results showed an increase in the syngas heating value and decreased tar content. To determine the performance, the effects of equivalent ratio, preheated air temperature, and air ratio were studied. When the equivalent ratio is increased, the flammable gas and LHV decrease. The optimum conditions were obtained for the equivalent ratio (ER) of 0.4, where the percentage of CO and H2 increased at an oxidation temperature of 902 °C. The variation of the air ratio has a stronger influence than the effect of the equivalent ratio because at the same equivalent ratio an increase in pyrolysis temperature of 674 °C is favorable to reforming tar from primary tar to secondary tar. The CO percentage increased significantly from 18.17% to 22.51%. Air preheating is useful to improve gasification performance, which was characterized by an increase in LHV from 5254 to 5976 kJ/kg. The optimum equivalent ratio and air ratio were 0.4 and 40:60, respectively, and effectively reduced the tar content from 50.02 to 27.82 mg/Nm3. The results of this study can be used to optimize multistage gasifier performance using air preheating and a multistage air inlet.

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Performance and emissions characteristics from port injection SINJAI engine 650 cc operating on bioethanol-gasoline blended fuels of 0%, 5%, 10%, 15% and 20% were investigated on water brake dynamometers with power capacity 120 hp. The properties of bioethanol were measured based on American Society for Testing Materials (ASTM) standards. Fuel consumption was measured by the time fuel consumption per 25 cc of fuel in a measuring glass whereas combustion air consumption was measured using an air flow meter. The emission parameters, exhaust gas temperature and air fuel ratio were measured using STARGAS exhaust gas analyzer. The increase of bioethanol content will increases the engine performance and reduces pollutan emission. The highest engine performance produced by E15 blended fuel with increased torsi, mean effective pressure and power output of 10,27 %, thermal efficiency 1,8% but specific fuel consumption increased approximatelly 12,42%. This condition occurs at engine speed 3000 - 3500 rpm. While the emission CO and HC emissions decreased significantly as a result of the leaning effect caused by the bioethanol addition. In this study, it was found that using bioetanol-gasoline blended fuels , the CO and HC emissions would be reduced appoximatelly by 55 and 32% Respectively.

Abstract. Multi-stage gasification process adding multiple air injection (at pyrolysis and oxidation) to reduce tar content and improve the efficiency. all components of the fuel can decompose perfectly into pyrolysis products and the total pyrolysis product also increases. The mean temperatures in the pyrolysis zone are respectively between 569 o C and 633 o C for the 0% and 90% Air Ratios. Temperature increases in the pyrolysis zone change the nature of the endothermal into exothermal and providing the heat energy for the drying, oxidation and reduction zones. While the temperature of the partial oxidation zone reaches 858 o C. For a total air flow of 10.5 Nm 3 /h with a 90% air ratio, the gasifier can produce a low tar content of 32.27 mg/Nm 3 when compared to 0% air ratio of 106.5 mg/Nm 3 . This result shown that multi-stage gasifier can reduce tar content by 30%.

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Pressure reducer merupakan komponen utama pada conversion kit pada mesin bahan bakar ganda (duel fuel engine) yang berfungsi sebagai penurun tekanan pada bahan bakar compressed Natural gas dari tangki sebesar ± 250 bar menjadi tekanan kerja pada injektor gas sebesar ± 2 bar, sehingga menyebabkan kekurangan pasokan jumlah bahan bakar dari pressure reducer yang berpengaruh tethadap penurunan performa mesin, baik pada saat perubahan putaran mesin secara tiba-tiba maupun perubahan beban mesin. Mengatasi permasalah tersebut maka diperlukan upaya untuk meningkatkan performa pressure reducer agar lebih adaptif terhadap perubahan kondisi mesin. Salah satu upaya yang dilakukan untuk peningkatan performa tersebut adalah menambah kekuatan konstanta pegas pada area chamber stage dua pressure reducer. Penelitian ini menggunakan mesin Diamond tipe DI 800 dengan sistem dual fuel model indirect injection. Metode yang dilakukan adalah menvariasikan kekuatan konstanta pegas (25,55 N/m, 26,55 N/m, dan 27,55 N/m). Hasil terbaik didapatkan pada konstanta pegas 27,55 N/m terjadi peningkatan jumlah laju aliran gas (mass flow rate) pada saluran keluar (outlet gas pressure reducer) sebesar 7,42%. Hal ini menunjukkan terjadi peningkatan performa pressure reducer pada saat penambahan kontanta pegas pada stage dua