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ÖZET Dünya petrol tüketiminin yaklaşık yansı ulaşımda kullanılmakta ve bu tüketimde benzin ve motorin önemli çevre kirliliği sorunları oluşturmaktadır. Dünya petrol rezervlerinin kullanılabilme süresi 43 yıldır. Çevre dostu yakıt arayışları ve yenilenebilir enerji kaynaklan kullanımına geçilmesi zorunluluğu, yeni motor yakıtı teknolojilerinin gerekliliğini ortaya koymaktadır. Yeni motor yakıtları arasında en önemli fueloil ve motorin seçeneği bitkisel yağlardır. Bitkisel yağlar, doğrudan veya modifikasyon teknikleri ile alternatif yakıt olarak değerlendirilmektedir. Bu çalışmada, pamuk tohumu yağının doğrudan fueloil ve motorin olarak değerlendirilebilirliğinin incelenmesi amaçlanmış ve pamuk tohumu yağının alternatif yakıt özellikleri konuya ilişkin sorun ve öneriler belirtilerek ortaya konulmuştur. iv SUMMARY DIRECT USE OF COOTONSEED OIL AS A FUEL ALTERNATIVE Worldwide concern over the foreseeable exhaustion of fossil energy resources, and availability and price of liquid fuels created substantial interest in alternative fuel sources, and biomass seems to be one of the promising solutions for current and future energy demands. Most of the energy-intensive sectors of society, such as agriculture, highway and railroad transportation, construction, and the military, are highly dependent on diesel fuel and fuel oil. Therefore, most of the recent research activities were directed toward fossil-based diesel fuel and fuel oil. Energy comsumption in Turkey is on the rise due to rapid industrilization and increasing population. An average 5% annual increase has been observed in the nation's energy consumption over the past 18 years. Although there has been 65% increase in the domestic energy production within the same time period it is still inadequate to satisfy the country's ever-growing demand. Amount the primary energy sources of Turkey domestic coal, hydro, and geothermal reserves are approximately 1% of the World's total, whereas oil and natural gas reserves are very limited. In 1995 58.4% of the total primary energy consumed in Turkey was imported and oil had the largest share (27 million tons) within the overall energy imports. Over 95% of the oil consumed Turkey is provided through imports and this has very significant effects on the nation's balance of payments. Transportation sector is highly dependent on imported oil making Turkey strategically and economically vulnerable to both supply disruptions and external price manipulations. It is therefore evident that high priority must be given to transportation fuel alternatives within Turkey's national energy agenda.Turkey's clean and sustainable energy sources include hydro, geothermal, solar, wind, and biomass. Contribution of biomass and hydro to the primary energy production has been traditionally high. Biomass is considered as one of the key renewable energy sources of the future due to its large potential, economic viability and various social and environmental benefits. Although it is rarely considered in official energy statistics, it is already the fourth largest source of energy in the world. Oil seeds have been one of the major biomass sources of fuel. History records that Rudolph Diesel, the inventor of the engine that bears his name, used vegetable oils as a diesel fuel alternative in his engines as early as 1900. For many years, the ready availability of inexpensive petroleum middle distillate fuels provided little incentive for experimenting with alternative, renewable fuels for Diesel engine and for heating systems. The energy crisis of the 1970's sparked a renewed interest in the use of vegetable oils as fuels and today the subject continues to attract attention because of the successful results obtained in the applications. Vegetable oils have heat contents approximately 90% of that of the diesel fuel. A major obstacle deterring their use in the direct-injection engine is their inherent high viscosities, which are nearly ten times that of the diesel fuel. Solution of the viscosity problem has been approached in at least four modification techniques (dilution, microemulsion, pyrolysis and transesterification). High viscosity leads to poor atomization and incomplete combustion of the fuel, formation of excessive carbon deposits on the injection nozzles and in the combustion chamber, and contamination of the lubricating oil with unburnt residues. It is known by the injection and spray characteristics. In this study, the evaluation of direct use of cottonseed oil as fuel (diesel fuel and fuel oil) has been investigated. Cottonseed oil was selected for the vistudy because of being used widely in our country. Also the flora and agricultural potential of our country are suitable for cottonseed cultivation for using as fuel. Moreover, according to unsaturation degree of cottonseed oil fatty acid composition, its composition is proper for direct use. This factor also effected the selection. In the experimental study, refined cottonseed oil was used. The fatty acid composition of cottonseed oil was subjected to capillary gas chromatographic analysis with the apparatus of Hewlett Packard 5890 series II fitted with a flame ionization detector (FID). The major oil characteristics like density, refractive index, acid value, saponification value, iodine value were also determined according to the standard methods of analysis of fats and oil. Cottonseed was found to be rich in oleic acid. The percentage (weight) of oleic acid in the oil is 72.18%. The oil characteristics of cottonseed oil are as follows: density, 20°C: 914.8 kg/m3; refractive index, 20°C: 1.4720; acid value:0.24 mg KOH/g; saponification value: 195.3 mg KOH/g; iodine value:65.48 g 1/100 g; fatty acids average molecular weight: 273.4 kg/mol; oil average molecular weight: 861.1 kg/mol. VIIDiesel fuel characteristics of cottonseed oil and base diesel fuel were determined according to standart ASTM D 975-90. Fuel oil characteristics of cottonseed oil and base fuel oil (heating oil type) were determined according to standart ASTM D 396- 90 and the results were given in Table 1. Cottonseed has got characteristics to be evaluated as heating oil. Cottonseed oil viscosity is higher than the viscosity of diesel fuel. But other fuel characteristics are within the range of the standard. Cottonseed oil is a potential renewable energy source. Cottonseed has to be cultivated for energy production and it has to take its place among other alternative fuels in energy planning and researches in Turkey. VIIITable 1. Fuel properties of cottonseed oil, diesel fuel and fuel oil. IX 38