No abstract

Currently, various methods have been developed to overcome the problems caused by garbage. Pyrolysis is one methode of waste processing which is considered to be prospective enough to be developed. It's because some advantages such as high conversion ratio and high energy content and potency as an alternative fuel in the future. Therefore, in this paper characteristics of pyrolysis will be studied. The waste materials used are catalyst and plastic waste. The resultant products of the pyrolysis process analyzed by Gas Chromatography / Mass Spectroscopy (GC / MS), while the thermal decomposition analysis was performed using Thermo Gravimetric Analysis (TGA). The results of pyrolysis process in isothermal conditions of a single component and a mixture of plastic waste and natural catalyst show that the final temperature of pyrolysis and the rate of heating affects to the distribution of pyrolysis products for all samples. As pyrolytic temperatures increase, liquid and gas products increase, while solid products tend to decrease. In the temperature range of 300°C, 400°C, 500°C, 600 o C pyrolysis temperature with a heating rate of 100°C / min is the ideal temperature for obtaining the pyrolysis product of the liquid fraction and and the maximum gas fraction for all waste types studied.

Efforts to improve the physical and chemical properties of vegetable oils as diesel fuels such as viscosity and calorific value are indispensable with the depletion of fossil oil reserves. Jatropha oil with long chain fatty acids and high degree of unsaturation is mixed with short chain saturated fatty acid coconut oil in various compositions. The mixture was heated and stirred for 30 min at 90 • C. This mixing leads to a decrease in viscosity which allows for the breaking of the bond. The fatty acid molecule structure undergoes transformation that changes the degree of unsaturation and the average length of the carbon chain. Consequently, the kinematic viscosity and flash point of the mixture decreases while its calorific value increases.

No abstract

Paraffin melting experienced in the nozzle-and-shell, tube-and-shell, and reducer-and-shell models in thermal storage with 3D numerical and experimental approach has been studied. The numerical study aims to evaluate the melting process and discover temperature distribution, liquid-solid interface, liquid fraction, and the average surface Nusselt number, while the aim of this experimental study is to determine the distribution of melting temperature. The comparison of temperature distribution between the numerical approach and experimental one indicates a good agreement. The comparison result between the three models shows that the melting process of the nozzle-and-shell model is the best, followed by tube-and-shell and reducer-and-shell models, successively. To finish the melting process, the time required is 6130 s for the nozzle-and-shell model, while tube-and-shell model requires 8210 s and reducer-and-shell model requires 12280 s.

The depletion of fossil fuel availability and increase of pollution due to the use of fossil fuels have forced the researcher to find a renewable-friendly energy source. One of the potential replacements is alcohol based fuel. This present study investigated experimentally the influence of ethanol addition on the engine performance, in terms of effective power, brake specific fuel consumption, and exhaust emissions of a gasoline spark ignition engine. The engine used in the research was a 4-stroke single cylinder, indirect injection system with engine capacity of 124.8cc, and compression ratio of 9.3:1. The experiments were conducted at eight different engine speeds ranging from 1500 rpm to 5000 rpm and 10 types of gasoline-ethanol mixtures (E10 to E100). The result showed that the effective power decreased with the increase of ethanol in the fuel blends for all variations of engine speed. Leaning effect of ethanol addition in the blend fuel caused the CO emissions to decrease greatly as well as the HC emissions. On average, gasoline engine fueled by pure ethanol reduced the CO emission level by more than 60 % in volume compared to the engine with gasoline fuel. On average, the maximum power of the engine with fuel blend was obtained at engine speed of around 2500 to 3000 rpm. For higher ethanol content on the fuel blend, the optimum shift to the lower engine speed. It can be concluded that engine operation with ethanol content on the fuel performed better in the lower engine speed.

This study aims to experimentally determine the role of intermolecular forces on the contact angle of vegetable oil droplets. Contact angles were recorded using a microscope and measured using digital software. The results show that the surface tension of vegetable oils is influenced by the London force between the electron clouds of molecules. The process of cooling increases vegetable oil contact angles, due to the decreased kinetic energy of constituent molecules and increased London force on the molecules. A decrease in temperature causes the surrounding water vapor to condense, which adheres to the droplet surface (due to the hydrophilic properties of molecules). Hydrogen bonds develop after moisture adheres to the surface. Further, water molecules on the droplet surface reduce the surface tension, because of hydrogen bonds between the molecules on the droplet surface and moisture. Hydrogen bonds among the molecules force water molecules to accumulate on the droplet surface, which suppresses the droplet surface; therefore the contact angle decreases.

Penelitian ini mengkaji peluang pengelolaan sampah perkotaan sebagai salah satu strategi mitigasidalam mengurangi emisi gas CH4 dan menciptakan ketahanan iklim Kota Semarang. Hal ini dipandangpenting karena Kota Semarang adalah salah satu kota pesisir yang rentan terhadap dampakperubahan iklim. Sudah dikenal bahwa tingginya timbunan sampah di TPA merupakan salah satufaktor yang berkontribusi terhadap tingginya emisi gas CH4 Kota Semarang. Studi ini menggunakanpendekatan kualitatif untuk mengidentifikasi dan menggambarkan tiga faktor ketahanan iklim, yaituurban system, social agent, dan urban institution, disertai dengan metode kuantitatif skoring yangdisarankan oleh IPCC untuk menemukan peluang beberapa strategi pengelolaan sampah dalam rangkamembentuk ketahanan iklim. Analisis menunjukkan: (1) strategi pengolahan sampah di TPST dan olehpihak ketiga di TPA Jatibarang mampu menurunkan emisi CH4 melampaui target RAN-PI (2) urbansystem yang dibangun termasuk kategori ‘cukup’ untuk membentuk ketahanan iklim, dan (3) socialagent dan urban institutions berkategori ‘baik’ untuk membentuk ketahanan iklim. Strategipengolahan sampah oleh pihak ketiga di TPA memiliki peluang kontribusi lebih besar terhadappembangunan ketahanan iklim dibandingkan strategi pengolahan sampah di Tempat PengolahanSampah Terpadu (TPST).Kata kunci: emisi CH4, perubahan iklim, mitigasi, strategi pengelolaan sampah, ketahanan iklim