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Öğe The Assessment of Wind and Sea Flow Energy Production from Seas by Using Energy Storage Unit(Institute of Electrical and Electronics Engineers Inc., 2018) Sener, A.S.; Aktas, A.; Kircicek, Y.The sea/ocean energy is a source of renewable energy sources with high energy potential in the nature. There is more than one kind of energy in the sea/ocean, and these are wind, wave, tide, flow energy. The aim of this work is to design a system that will turn multiple energy sources into electricity. Utilizing the wind and surface flow energy in offshore, a platform with a high potential hybrid power generation system model was created. In order to ensure the durability of these intermittent and unstable energy types that are inherent in renewable energy sources, a hybrid energy storage unit which are composed from battery and ultra-capacitor has been implemented to the proposed hybrid power generation system to provide the optimum solution for meeting the demand side and producing high quality electricity. In this study, all units were simulated using the hybrid power generation system and the hybrid energy storage system MATLAB/Simulink program. The hybrid power generation system and the hybrid energy storage system transfer a single-phase inverter with a single DC bus. The smart energy management algorithm in the system provides control of direct current converter and inverter circuits take into account on all power values. In this study, current, voltage and power graphical results are given by examining the dynamic behavior of possible working states of the total system. By taking the results of Case 1 from the probable working states of the system, it helps to see fast and predictable results of the simulation studies before the experimental studies. © 2018 IEEE.Öğe Biodiesel production from leftover olive cake(2012) Aktas, A.; Ozer, S.Leftover olive cake is a kind of biomass fuel being used with high calorific value for heating in industry and at homes. Even in the best technologies oil may remain in proportion of %8-10 in its cake as a result of processing olive. Oil obtained by the method of extraction from leftover olive cake is called crude pomace oil. Crude pomace oil after refining processes may also be used as olive pomace oil. Crude pomace oil is a biomass fuel with high calorific value available as fuel in compression-ignition (CI) engines. However due to high free fatty acid (FFA), in direct use of engines causes problems because of negative effects such as blockage of the fuel pump and injectors, bad odour during combustion, the amount of sediment left on the cylinders and injectors, high viscosity and density value. For this reason properties of crude pomace oil must be improved. In this study the way of improving by the method of transesterification is preferred for crude pomace oil to be used in engines. Methanol (CH3OH) in the rate of purity %99.7, Potassium Hydroxide (KOH) and Sodium Hydroxide (NaOH) in the rate of purity %98.5, sulphuric acid (H2SO4) in the rate of % 95.5 are used for transesterification reaction. It is determined that FFA amount specified according to three different methods is high for transesterification conversion. For this reason biodiesel production of crude pomace oil was carried out in three stages. In the first stage the improvement of the amount of FFA of the oil is aimed. Therefore in the 1st stage CH3OH in the mole fraction of 20:1 (alcohol/oil) and with H2SO4 of %10 in volume is subjected to reaction for an hour at 55-60oC temperature. As to in the second stage CH3OH in the mole fraction of 40:1 (alcohol/oil) and with H2SO4 of %5 in volume after being subjected to reaction for an hour at 55-60 oC temperature the reaction was repeated in company with KOH and NaOH for the production of biodiesel. It is observed that the properties of the obtained fuel are in accordance with the standards of EN 14214 and ASTM D-6751. © Sila Science.Öğe Biodiesel production from waste melon seeds and using it as alternative fuel in direct injection diesel engine(Elsevier Sci Ltd, 2010) Aktas, A.; Sekmen, Y.; Sekmen, P.Melon seeds containing similar to 30% oil are wasted after the fruit is consumed. The chemical and physical properties of melon seed oil are very similar to vegetable oils used as biodiesel fuel. There are no studies regarding the use of melon seed oil or its esters as fuel in literature. In this study, oil was extracted from waste melon seeds and transformed to melon seed oil methyl ester (MSOME) by transesterification process. This fuel is used in a four stroke single cylinder direct injection diesel engine, and its effects on performance and emissions were investigated for various engine speeds at full load. In addition, diesel fuel no. 2 and soy bean oil methyl ester (SOME) is used as fuel under the same operating conditions for comparison purposes. According to the experiment results, specific fuel consumption is found to be more in both biodiesel fuels compared to diesel fuel, and the engine torque is 1-6% lower with MSOME and 3-5% with SOME compared to diesel fuel. Exhaust gas temperature is lower with MSOME and SOME than with diesel fuel. Furthermore, it is found that CO and HC emissions and smoke density are generally lower in both biodiesel fuels. However, NOx emission is slightly higher for SOME and MSOME than that for diesel fuel.Öğe The effects of advance fuel injection on engine performance and exhaust emissions of a diesel engine fuelled with biodiesel(2008) Aktas, A.; Sekmen, Y.Biodiesel is an oxygenated, sulphur-free, non-toxic, biodegradable and renewable alternative diesel fuel. It is known that CO, HC and smoke emissions of biodiesel are lower than those of diesel fuel. It is used without any significant setting and modification in diesel engines. Fuel injection timing is one of the significant parameters affecting the performance and emissions in diesel engines. By optimising fuel injection parameters, improvement in fuel economy as well as reduction in harmful exhaust emissions can be effected. In this study, the effects of fuel injection advance on engine performance and exhaust emissions were investigated experimentally in a fourstroke single cylinder direct injection diesel engine fuelled with biodiesel. Engine torque, brake power, specific fuel consumption, exhaust gas temperatures, CO, HC and NOx emissions were measured for injection timings of 24.9, 26.6 and 28.5°CA at full load. By increasing injection timing to 26.6°CA when running on biodiesel, engine torque and brake power increased by about 6%, and 8% improvement in specific fuel consumption were observed. In addition, it was also determined that CO and HC emissions decreased while NOx emissions increased by between 4-11%.Öğe Effects of LPG percentage to performance and exhaust emissions in a dual fuel engine(2010) Aktas, A.; Dogan, O.In this study, an experimental investigation was presented to determine the effects of various ratios of Liquefied Petroleum Gas (LPG), containing 30% propane and 70% butane, on the performance and exhaust emission in a dual fuel engine with direct injection. The tests were performed at maximum torque speed of 2600 rpm with a various loads of maximum torque (20%, 40%, 60%, 80% and 100%) by using pure diesel fuel or dual fuel containing 20%, 40%, 60%, 80% and 90% of LPG. The test results showed that the smoke and Nitrogen oxide (NOx) emissions decrease, while carbon monoxide (CO) and hydrocarbon (HC) emissions increase at all mixtures of LPG and diesel fuel. Brake specific fuel consumption (bsfc) decreases by 3.5-15% with 40% LPG while the load increases. Exhaust gas temperatures at the mixture fuel were lower than that of diesel fuel in general. It was concluded that LPG can be used with diesel fuel as a mixture up to 40-60% of LPG, provided that CO and HC emissions can be lowered.Öğe Effects of using blends of melon kernel oil methyl ester and Diesel fuel on the engine performance and emissions(2012) Aktas, A.Many types of vegetable oils and their methyl esters were tested in diesel engines as an alternative fuel. Melon has a high potential of production. Wasted Melon kernel, generally has a high oil ratio and similar properties with other biodiesel sources and can be used for biodiesel production. In this study, the oil was produced from melon kernel and then converted to the biodiesel. The effects of pure melon kernel oil methyl ester (MKOME) and its 2% and 20% blends with Diesel fuel no.2. on performance and emissions was investigated in a single cylinder, direct injection diesel engine at full load and various engine speeds. Melon kernel oil methyl ester blended with diesel by 2% produced slightly higher torque, power and nitrogen oxides emission along with lower carbon monoxide, hydrocarbon and smoke density. Torque, power, carbon monoxide and hydrocarbon emissions were decreased as the ratio of melon kernel oil methyl ester is increased. The lowest Hydrocarbon emission was measured for 20% melon kernel oil methyl ester-diesel fuel blend. © Sila Science.Öğe An experimental investigation of the effect of refrigerant charge level on an automotive air conditioning system(2011) Atik, K.; Aktas, A.During the last 25 years automotive air conditioning (AAC) systems have significant development introduced by the industry and research institutes in the world to minimize the global warming threat to the environment. This paper reports the results of a study on the performance of an AAC system with measuring the compressor driving speed and the refrigerant leakage. For this purpose an experimental set up is designed and constructed to investigate the system performance. Although, the manufacturer's recommended amount for the tests with R-134a as refrigerant was 750 g, the experiments were also carried out by selecting different amount of the same refrigerant charges to analyse the coefficient of performance (COP), the cooling capacity and the compressor power change with respect to the rotating speed of the compressor. The evaluation of experimental data revealed that the best cooling capacity was achieved at 500 g refrigerant charge. Although, while the charge level decreased 40% below or increased 20% above the 500g of the charge amount, cooling capacity loss increased up to 25% when optimum value of 500 g of the cooling refrigerant was utilized. The test results proved in each case that increasing the compressor driving speed cause almost a linear change in the corresponding power level. The test results also shown that COP of the cooling system was decreased effectively when the revolution speed increased for any specified charge amount of the refrigerant. ©2008 TIBTD Printed in Turkey.Öğe Recovery of waste heat energy from gasoline engine exhaust(Maney Publishing, 2008) Aktas, A.; Dogu, A.Since the working gas in a conventional internal combustion engine cycle is not exhausted at ambient temperature, approximately one-third of total fuel input energy is lost with the exhaust gases. The aim of this study is to investigate the amount of rejected energy to exhaust of a gasoline engine and to recovery of this through a small gas turbine. Furthermore, whether the use of the turbine used for the recovery of the energy had a detrimental effect engine emission was also examined. The experiments were conducted at partial load. It was found that the maximum available energy in the exhaust system was 8450 W. However, only 1.3% of this could be recovered through a single stage turbine and the turbine mounted to the exhaust system only slightly influenced the engine emission.
