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In this study, the performance and exhaust emissions of homogeneous charge compression ignition engine fueled by gasoline fuel were modeled by using the response surface method. The effect of independent variables-compression ratio, engine speed inlet air temperature, lambda value, and research octane number value-on responses such as indicated mean effective pressure, indicated thermal efficiency, maximum pressure rise rate, specific fuel consumption, cyclic differences was studied together; unburned hydrocarbons, carbon monoxide, and nitrogen oxide are predicted by multi-regression. The desirability function was used to define an optimum combination of engine operating conditions. High desirability of 77% was achieved at the compression ratio of 12, intake air temperature of 333 K, lambda value of 1.8, engine speed of 935 rpm, and RON40. This homogeneous charge compression ignition engine operating condition was suggested as the optimum independent variables. At this point, 5.08 of indicated mean effective pressure, 35% of indicated thermal efficiency, 243.28 g/kWh of specific fuel consumption, 4.43 bar/CA of maximum pressure rise rate, and 3% of COVimep were achieved as responses. Additionally, the optimum values of engine emissions were found to be 355.586 ppm for unburned hydrocarbons, 3% for carbon monoxide, and 0 ppm for nitrogen oxide. This study showed that changes in performance and exhaust emissions of a homogeneous charge compression ignition engine could be successfully predicted using the response surface method. This study, which was carried out with the RSM technique, reduced the hundreds of data points needed, and all variables could be examined with only 60 data points.

With the increase in global energy demand, air pollution becoming uncontrollable does not fall off the agenda. It is inevitable to use and spread of renewable energy sources to make energy production cleaner, more reliable and sustainable. In studies for this purpose, the use of fuel cell systems comes to the forefront thanks to its many advantages. The use of hybrid systems is becoming more common day by day in order to minimize the efficiency losses that may occur in the energy production, use and waste management process, to ensure energy reliability and to prevent systemic problems. In this study, hybrid systems created with fuel cells are discussed in detail, and examined under three main headings: hybrid systems created with renewable energy sources, created with storage devices, and created for energy recovery. It has been observed that the main purpose of hybrid systems created with renewable energy sources is to ensure energy reliability. In addition, the electrical energy required for the electrolysis of hydrogen used as fuel in fuel cells can be provided by photovoltaic panels or wind turbines, thus eliminating fuel storage and transportation problems. In hybrid systems created with storage devices, it is aimed to prevent instantaneous interruptions in the system by meeting the instantaneous power needed by the system and successful results have been achieved. In the hybrid systems created for energy recovery, it has been seen that it is possible to recover the heat and unburned fuel energy released from the fuel cell with thermophotovoltaic cells, gas turbines and heat exchangers.

Bu çalışmada, Unigraphics NX programının CAD modülü kullanılarak uzun, ince ve esnek karbon fiber takviyeli kompozit bir kapak tasarlanmıştır. Bu tasarıma ANSYS ortamında sonlu elemanlar yöntemi ile modal analiz uygulanarak farklı modlar için analiz sonuçları elde edilmiştir. Modal analiz süreci ayrıntılı olarak anlatılmış ve temel yöntemler ve matematiksel denklemlerden bahsedilmiştir. Analiz sonuçları detaylı bir şekilde incelenmiş, eğilme ve burulma koşulları değerlendirilmiştir. Analiz sonuçlarına göre kompozit kapağın direngenliğini iyileştirmek için bir kaburga tasarımı yapılmış ve ilk tasarıma eklenmiştir. Nervürlü kapak tasarımı için bir modal analiz süreci gerçekleştirilmiştir. Modal analiz sonucunda farklı mod parametrelerindeki doğal frekans değerleri elde edilmiş ve değerlendirilmiştir. İlk kapak tasarımına kaburga eklenmesi ile mod 1, mod 2, mod 3, mod 4, mod 5 ve mod 6 değerlerinde sırasıyla %35,52, % 38,79,% 58,07,% 129,11,% 100,35 ve % 106,65'lik bir iyileşme gözlenmiştir., In this study, a long, thin and flexible carbon fiber reinforced composite cover was designed using the CAD module of Unigraphics NX program. Analysis results for different modes were obtained by applying modal analysis to this design with finite element method in ANSYS environment. The modal analysis process is explained in detail, and basic methods and mathematical equations are mentioned. Analysis results were examined in detail, and bending and torsion conditions were evaluated. Based on the analysis results, in order to improve the stiffness of the composite cover, a rib design was made and added to the initial design. A modal analysis process was carried out for ribbed cover design. As a result of the modal analysis, natural frequency values in different mode parameters were obtained and evaluated. With the addition of ribs to the initial valve design, an improvement of %35.52, % 38.79,% 58.07,% 129.11,% 100.35 and % 106.65 was observed in mode 1, mode 2, mode 3, mode 4, mode 5 and mode 6 values, respectively.