Milan Tomić

Bio: Milan Tomić is an academic researcher from University of Novi Sad. The author has contributed to research in topics: Biodiesel & Transesterification. The author has an hindex of 13, co-authored 35 publications receiving 382 citations.

Effects of fossil diesel and biodiesel blends on the performances and emissions of agricultural tractor engines

Abstract: Rapid growth in the energy consumption has conditioned the need for discovering the alternative energy resources which would be adapted to the existing engine constructions and which would satisfy the additional criteria related to the renewability, ecology and reliability of use. Introduction of biodiesel has been the focus of attention over the last ten years. The aim of this research is to investigate the influence of biodiesel on the performances and exhaust gas emissions of medium power agricultural tractor engines (37-66 kW). The reason for the selection of this category is that those types of tractors are most frequently used in agriculture. In this research biodiesel produced from sunflower oil was blended with fossil diesel. Biodiesel, fossil diesel and fossil diesel blends with 15, 25, 50 and 75%v/v biodiesel were tested for their influence on the engine performances and emissions. The testing was performed on a four-cylinder diesel engine with 48 kW rated power. The experimental research on the engine performances was conducted in compliance with OECD test CODE 2, and the exhaust gas emissions were tested according to the ISO 8178-4, C1. The use of biodiesel and fossil diesel blends reduced the engine power with the increase of biodiesel share in the blend. However, the exception was the blend with 15%v/v biodiesel which induced a slight increase in the engine power. Depending on the share of biodiesel in the blend all blends fuels showed increased specific fuel consumption compared to the fossil diesel. Thermal efficiency increased as a result of more complete combustion of biodiesel and fossil diesel blends. The exhaust gas emissions implied that the addition of biodiesel reduced the content of CO2 and CO, as well as the temperature of exhaust gases, but it increased the emission of NOx.

Reduction of free fatty acids in waste oil for biodiesel production by glycerolysis: investigation and optimization of process parameters

Abstract: Abstract Influence of the process parameters for the industrially relevant reaction of free fatty acid (FFA) with glycerol is investigated. Furthermore, several drying techniques are investigated and a novel method is suggested that can provide more realistic experimental conditions. Silica as an absorbent is found to be a more suitable method for water removal than distillation or carrier gas. Using response surface methodology, important parameters are identified and optimal conditions found. Empirical correlation is developed to account for the most important parameters. Both oil:glycerol ratio and temperature have optimal values for which the highest conversion can be achieved. Interestingly, the highest conversion can be obtained at 220°C; above this temperature the conversion decreases. It is found that the influence of oil:glycerol ratio also exhibits anomalous behavior, where conversion is constant and decreases above a certain value. At optimal conditions, the FFA is reduced to 1.6% from the initial 8.6%.

Power delivery efficiency of a wheeled tractor at oblique drawbar force

Abstract: The offset position of an implement creates an oblique drawbar force. This force occurs when the resistance direction of the implement is at a certain angle with respect to the longitudinal axis of the tractor (tractor traction direction). The focus of this study was to demonstrate the dependence of wheeled tractor power delivery efficiency on wheel slippage for central and oblique drawbar forces, both on plowed and unplowed stubble. For this purpose, the travel speed of tractor, wheel slippage, drawbar force and engine speed were measured. Mathematical models were formed using a nonlinear regression analysis, and after that, an algorithm for calculating the power delivery efficiency of wheeled tractors depending on the drawbar force and the angle of the drawbar force was developed. This method allowed us to determine the dependence of the power delivery efficiency on the wheel slippage for different angles of the drawbar force. The highest power delivery efficiency of a tractor is achieved at a central drawbar force (angle of the oblique drawbar force equals zero). Results showed the influence of oblique drawbar force on the power delivery efficiency of the wheeled tractor on soft and loose types of soil. Power delivery efficiency of the tractor on unplowed stubble decreased by 6.7% when the angle of the oblique drawbar force increased to 10 degrees, and by 15.0% when the angle of the oblique drawbar force increased to 20 degrees. On plowed stubble, power delivery efficiency decreased by 10.4% at a 10 degree angle of oblique drawbar force and by 21.9% at an angle of oblique drawbar force of 20 degrees. The importance of properly attaching the implement to the tractor was also confirmed.

Current state of the biodiesel production and the indigenous feedstock potential in Serbia

Abstract: This paper summarizes the biodiesel production capacities and the indigenous oil-based feedstock potential of Serbia for the first time. The current demands and future trends in diesel fuel consumption in Serbia are presented in order to estimate the biodiesel perspectives. The comprehensive review explores the potentials of the available conventional biodiesel sources (oilseed crops), as well as the next generation biodiesel sources, including waste cooking oil and oil from non-edible agro-food wastes that were previously reported as potential biodiesel feedstock in Europe. Results suggest that the Serbian agriculture can provide oilseed crops for the production of 128,000–266,000 t of biodiesel annually in addition to the quantities of oilseed crops required by the domestic food and fodder industries. Nevertheless, selecting edible vegetable oils as a potential feedstock for biodiesel cannot be considered as a long-term choice due to the associated “food versus fuel” debate. Thus, exploring the non-edible waste feedstock is important. Around 10,000 t of biodiesel could be produced from the collectable waste cooking oil. Other potential alternative oil resources indigenous for Serbia, such as tomato, grape and tobacco seeds, can provide raw material for the production of further ca. 8,000 t of biodiesel annually. Lack of governmental incentives and higher profitability of the edible oil sector have caused that the installed capacities for biodiesel production (ca. 126,000 t annually) are largely out of operation since 2008. Nevertheless, the results suggest that with the introduction of appropriate measures there is a realistic basis to fulfil the goals set by the National Renewable Energy Action Plan which requires that the annual biodiesel production from domestic sources should reach 98,000 t by 2020 in Serbia.

Agriculture and rural development

Abstract: Although most countries in the world are rapidly urbanizing, the majority of the global population – particularly the poor – continue to live in rural areas. This Handbook rejects the popular notion that urbanization should be universally encouraged and presents clear evidence of the vital importance of rural people and places, particularly in terms of environmental conservation. Expert contributors from around the world explore how global trends, state policies and grassroots movements affect contemporary rural areas in both developed and developing countries.

Impact of alcohol on biodiesel production and properties

Abstract: Due to rapid industrialisation and use of advanced technologies there has been increase in the consumption of fossil fuels, especially petroleum. Increasing needs are reciprocally proportionate to diminishing reserves of coal and petroleum. So, the exaggerated to be fulfilled and to curb the problem of increasing fuel prices; researchers are putting their efforts to produce an alternative fuel from replenish able resources on large scale. Biodiesel itself is proving to be a reliable and competent competitor to non-renewable petroleum which is being produced from commonly accustomed plants for instancerapeseed, soybean, sunflower and palm etc. But, complication is that it becomes a problem for in-availability of these oils for foods. Now non-edible raw materials oils such as Pongamia, Jatropha, Mahua, Moringa seed oil etc. have been used to raise the standard of these oils and being produced to complete the level of petroleum and be proven as the best resources for biodiesel production in all approaches both technically and economically. In this paper emphasis has been laid down to review the impact of higher alcohols, use of different raw materials for biodiesel preparation and effect of their composition on Oxidation Stability and Cold Flow properties. Moreover, various production technologies used to produce biodiesel were also reviewed and comparison was done among them for better yield. Further, an attempt has been made to investigate the effect of higher alcohols on biodiesel yield and its properties. The study concludes that oxidation stability depends upon unsaturation mainly linoleic acid and lenolenic acid. Moringa olifera , Moroccan frying oil, Schleichera oleosa L. oil, Moringa peregeria are prospective oils as per oxidative stability characteristics. In contrast to it, cold flow properties depend upon saturation and suggests that having more saturated fatty acids result in poor cold flow properties.