Biodiesel is one of the most popular prospective alternative fuels and can be obtained from a variety of sources. Waste frying oil is one such source along with the various raw vegetable oils. However, some specific technical treatments are required to improve certain fuel properties such as viscosity and calorific value of the biodiesel being obtained from waste cooking oil methyl ester (WCOME). Various treatments are applied depending on the source and therefore the composition of the cooking oil. This research investigated the performance of WCOME as an alternative biofuel in a four-stroke direct injection diesel engine. An 8-mode test was undertaken with diesel fuel and five WCOME blends. The best compromise blend in terms of performance and emissions was identified. Results showed that energy utilization factors of the blends were similar within the range of the operational parameters (speed, load and WCOME content). Increasing biodiesel content produced slightly more smoke and NOx for a great majority of test points, while the CO and THC emissions were lower.

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ÖzBu çalışmada, R600a, R290 ve R152a akışkanı kullanılarak tasarlanan üç farklı Organik Rankine Çevrimi (ORÇ) modelinin ekserji analizi yapılmıştır. Bu analiz, farklı türbin giriş sıcaklığı ( o C) ve türbin giriş basıncı (kPa) değerlerinde yapılmıştır. Bu giriş parametreleri kullanılarak, ısıl verim, sistemin ekserji verimi ve birim kütle başına bileşenlerde oluşan tersinmezlik değerleri üç farklı akışkan içeren ORÇ için tespit edilmiştir. Ekserji analizi, MATLAB ve Engineering Equation Solver (EES) yazılımı kullanılarak yapılmıştır. ORÇ teknolojisinde çeşitli tipteki akışkanların kıyaslamalı olarak ekserji analizinin yapılabilmesi için, kuru tip akışkan için R600a, izentropik tip akışkan için R290, ıslak tip akışkan için ise R152a akışkanı seçilerek, 150 giriş ve 900 çıkış numerik veri kullanılmıştır. Bu çalışmada, MATLAB ve EES yazılımı kullanılarak oluşturulan üç farklı model ile Organik Rankine çevriminin ekserji analizinin başarıyla uygulanabildiği gösterilmiş, farklı akışkan kullanılmasının bileşenlerde meydana gelen tersinmezlik değerlerine etkisi belirtilmiştir. AbstractIn this study, exergy analysis was performed on three different Organic Rankine Cycle (ORC) models designed using R600a, R290 and R152a fluids. This analysis was carried out at different values of condenser inlet pressure (kPa), turbine inlet temperature ( o C) and turbine inlet pressure (kPa). Using these input parameters, the thermal efficiency, the exergy of the system, and the irreversibility values of the components per unit mass were determined for the ORC containing three different fluids. Exergy analysis was performed using the MATLAB and Engineering Equation Solver (EES) software. R600a for dry type fluid, R290 for isentropic type fluid and R152a fluid for wet type fluid were selected and 150 input and 900 output numerical test values were used in order to perform exergy analysis in different types of fluids in ORC technology. In this study, we show that the exergy analysis of the Organic Rankine cycle can be successfully applied with three different models created using the MATLAB and EES software, and the effect of using different fluids on the irreversibility values that occur in the components is indicated.

In this study, the effect of evaporator pinch point temperature difference (∆TPP,e) value in Organic Rankine Cycle (ORC) on system performance was determined. Under different applications of ORC, optimum ∆TPP,e value has been determined in ORC systems designed with different heat source temperatures. By changing the ∆TPP,e value, the heat input provided to the system, the mass flow of organic fluid, the evaporation pressure and the enthalpy drop in the turbine are affected. In thermodynamic optimization, the objective function is determined as turbine power maximization. Genetic algorithm optimization technique is used. Within the scope of low and high temperature ORC applications, the optimum ∆TPP,e value of different organic fluids under 10 different heat source temperatures (Low, 90-130 °C; High, 250-290 °C) has been determined. Low temperature organic fluids have been selected from dry, isentropic, wet and new-generation categories. High temperature organic fluids have been selected from the alkane, aromatic hydrocarbon, and siloxane categories. The effect of ∆TPP,e on fluids of different categories was determined for low and high temperature ORCs. It has been determined that taking the ∆TPP,e value constant regardless of the heat source temperature and organic fluid causes performance loss in ORC.

In this study, the effect of turbine inlet temperature change on organic fluid performance in three different Organic Rankine Cycle (ORC) models designed using R113, R123 and isopentane fluid was determined. With the MATLAB and EES program, 17 different models have been formed for the heat source temperature that changes with the turbine inlet temperature. By analyzing the determined organic fluids on the generated models, the amount of heat entering the system, the work produced by the turbine, thermal efficiency, total exergy destruction and exergy efficiency were determined. While turbine inlet temperature is 80 o C and heat source temperature is 110 o C, isopentane fluid can reach maximum 8.8% while R113 fluid has reached 12.4% in same design conditions. With all cases examined, it is stated that isopentane fluid needs more heat input per unit mass compared to other fluids. While the maximum value of 531.7 kJ/kg heat input is required for isopentane fluid, R113 and R123 fluids require a maximum of 220.2 kJ/kg and 246.8 kJ/kg respectively. When the work values obtained from the turbine are examined, it is stated that R113 and R123 fluids show close properties. In this study, a maximum of 21.63 kJ/kg and 26.98 kJ / kg turbines were obtained for R113 and R123, while a 45.35 kJ/kg turbine work was obtained in the model using isopentane fluid. In exergy analysis, it was found that the best exergy efficiency performance was obtained in R113 fluid with 56.3%. In addition, the effect of overheating the organic fluid on the energy and exergy efficiency of the system was determined by the constant acceptance of the turbine inlet pressure.