http://aoatools.aua.gr/pilotec/files/bibliography/Biofuels%20(alcohols%20and%20biodiesel)%20applications%20as%20fuels%20for%20internal-4026835713/Biofuels%20(alcohols%20and%20biodiesel)%20applications%20as%20fuels%20for%20internal.pdf

Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines

Biodiesel production from high FFA rubber seed oil

Vegetable oils and animal fats can be transesterified to biodiesel for use as an alternative diesel fuel.
Conversion of low cost feedstocks such as used frying oils is complicated if the oils contain large amounts of free fatty
acids that will form soaps with alkaline catalysts. The soaps can prevent separation of the biodiesel from the glycerin
fraction. Alternative processes are available that use an acid catalyst. The objective of this study was to investigate the
effect of process variables on acid-catalyzed transesterification. The molar ratio of alcohol, reaction temperature, catalyst
amount, reaction time, water content, and free fatty acids were investigated to determine the best strategy for producing
biodiesel. Food grade soybean oil was used to prepare esters using excess methanol and sulfuric acid as a catalyst. To
compare the effect of different alcohol types on ester formation, methanol, ethanol, 2-propanol, and n-butanol were
compared. The American Oil Chemists’ Society Method Ca 14-56 was used to measure the biodiesel’s total glycerin
amount as an indicator of the completeness of the reaction. It was found that acid catalysis can provide high conversion
rates but much longer times are required than for alkaline catalysts. The acid catalyst also requires the concentration of
water to be less than 0.5%, which is about the same as is required for alkaline catalysts. Water formed by the
esterification of free fatty acids limited their presence in the oil to 5%.

Biodiesel production via acid catalysis

This article is a literature review on biodiesel production, combustion, performance and emissions. This study is based on the reports of about 130 scientists who published their results between 1980 and 2008. As the fossil fuels are depleting day by day, there is a need to find out an alternative fuel to fulfill the energy demand of the world. Biodiesel is one of the best available sources to fulfill the energy demand of the world. More than 350 oil-bearing crops identified, among which some only considered as potential alternative fuels for diesel engines. The scientists and researchers conducted tests by using different oils and their blends with diesel. A vast majority of the scientists reported that short-term engine tests using vegetable oils as fuels were very promising but the long-term test results showed higher carbon built up and lubricating oil contamination resulting in engine failure. They concluded that vegetable oils, either chemically altered or blended with diesel to prevent the engine failure. It was reported that the combustion characteristics of biodiesel are similar as diesel and blends were found shorter ignition delay, higher ignition temperature, higher ignition pressure and peak heat release. The engine power output was found to be equivalent to that of diesel fuel. In addition, it observed that the base catalysts are more effective than acid catalysts and enzymes.

A review on biodiesel production, combustion, emissions and performance

Biodiesel is an alternative fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Previous research has shown that biodiesel-fueled engines produce less carbon monoxide, unburned hydrocarbons, and particulate emissions compared to diesel fuel. One drawback of biodiesel is that it is more prone to oxidation than petroleum-based diesel fuel. In its advanced stages, this oxidation can cause the fuel to become acidic and to form insoluble gums and sediments that can plug fuel filters. The objective of this study was to evaluate the impact of oxidized biodiesel on engine performance and emissions. A John Deere 4276T turbocharged DI diesel engine was fueled with oxidized and unoxidized biodiesel and the performance and emissions were compared with No. 2 diesel fuel. The neat biodiesels, 20% blends, and the base fuel (No. 2 diesel) were tested at two different loads (100 and 20%) and three injection timings (3° advanced, standard; 3° retarded). The tests were performed at steady-state conditions at a single engine speed of 1400 rpm. The engine performance of the neat biodiesels and their blends was similar to that of No. 2 diesel fuel with the same thermal efficiency, but higher fuel consumption. Compared with unoxidized biodiesel, oxidized neat biodiesel produced 15 and 16% lower exhaust carbon monoxide and hydrocarbons, respectively. No statistically significant difference was found between the oxides of nitrogen and smoke emissions from oxidized and unoxidized biodiesel.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=12949&context=rtd

Kyle W. Scholl

Papers

Combustion of Soybean Oil Methyl Ester in a Direct Injection Diesel Engine