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Biofuels are expanding continuously in global market as one of renewable options to replace fossil fuels. Biodiesel is the most commonly used biofuel that can be blended into conventional diesels in any proportion. However, higher biodiesel blends may cause problems. One of its problems is precipitation formation arise from biodiesel may clog fuel filter at low temperature. This study focuses on fuel and environment factors on biodiesel precipitation and their influence degree on fuel filter clogging. The results indicate that monoglycerides and temperature have strong correlation with precipitate weight. Moreover, quantitative effect of precipitate weight on filter clogging was clarified.

The higher portion of biodiesel blended fuel will result in lower power output since biodiesel itself has lower energy input (B20 gave about 3% lower torque output at peak torque speed). In the ELR (Engine Load Response) Test Cycle, biodiesel blended fuel emitted less smoke than diesel fuel, while CO and NOx emission of biodiesel blended fuel and diesel fuel are comparable. Biodiesel particulate matter (PM) seemed to be higher than diesel fuel. In addition, additized biodiesel blended fuels (B5, B10 and B20) proved qualitative in oxidation stability, acid value, etc. Biodiesel specific lubricant confirmed its functions by evaluating the viscosity increase, fuel dilution, TAN, TBN and wear metal content during engine durability test. The used oil analysis affirmed that the lubricant could effectively be used with particular biodiesel blended fuel in advanced, heavy-duty common-rail DI diesel engines.

This study focused on the characterization, in term of quality, of intake valve and combustion chamber deposits collected by Toyota 1G-FE IVD test, which was developed for in-house IVD test in the Petroleum Authority of Thailand. Various analytical techniques were utilized to characterize deposits according to elemental analysis, thermal gravimetry analysis (TGA) and infrared spectroscopy in combination with solvent extraction. The results indicate that IVD contains more hydrocarbon oil and heavy fraction of gasoline than CCD, while the contents of organic oxidized products, carbonized compounds and inorganic additives in IVD are less. Resulting from hexane soluble extraction, the gasoline detergent additives in IVD are confirmed. The TGA result shows that PEA additive can be decomposed at lower temperature than PIBA additives. Comparing between piston top and cylinder head CCD, it was determined that “Oil up” phenomenon occurred at piston top more than cylinder head.

Thailand Ministry of Commerce regulates that a deposit control additive being added to market gasoline must pass BMW 318i's IVD test and Chrysler 2.2L's PFI test. A fleet test on how commercial IVD detergent additive packages contribute to PFI, IVD, and CCD is done. Based on the highest market share in Thailand, twelve Toyota Corolla are selected. Three commercial IVD detergent additive packages passing the above test: Polyether amine, Polyisobutylene amine, and Polyisobutylene succinimide, each combined with synthetic carrier fluid are used to represent the different classes of IVD detergent additive. The test vehicles are assigned into 3 groups. Each group of vehicles runs on base fuel and three additized fuel, accumulated 20,000 km. (40% city driving and 60% highway driving) in each test in the program. Result indicates that base gasoline in Thailand is not affective to port fuel injector. Therefore, we are unable to differentiate PFI 's performance of each additive.

The purpose of this study is to evaluate the effect of gasoline compositions and properties on vehicle tailpipe emissions in order to propose the automotive gasoline specifications in Thailand to be revised by the year 2000. A total of 270 exhaust emissions measurements were conducted using fifteen fuels according to Thailand emission standard test, TISI 1280 - 2538 (91/441/EEC). Six cars with different fuel supply systems or emission control devices were selected for the test based on the market share in Thailand. The following eight fuel parameters were examined: Reid Vapor Pressure (RVP), the 50 th percent distillation temperature (T50) and content of aromatics, olefins, benzene, MTBE, ethanol and sulfur. Total hydrocarbon (THC), carbon monoxide (CO), oxides of nitrogen (NOx) and toxic air pollutants such as benzene, 1,3-butadiene and carbonyl compounds were analyzed.