1,720,993 research outputs found
A Comprehensive Review on Stirling Engines
Full text linkStirling engines work with all kinds of heat sources thanks to the external heat supply. It has many advantages over internal combustion engines, especially in terms of noise emissions and pollutant emissions. Since the first Stirling engine invented by Robert Stirling, development work continues on it. Considering the problems caused by fossil fuels, Stirling engines are promising in the recovery of solar energy, geothermal energy and waste heat. As a result of the studies carried out from the past to the present, many Stirling engine types, cylinder configurations and drive mechanisms have been designed. In this study, the im-portance, advantages-disadvantages, usage areas and working principles of Stirling engines are explained. The Stirling cycle has been analyzed in detail. Carnot cycle and Ericsson cycle are mentioned and these three cycles are compared with each other in terms of work and efficiency. Stirling engine classifications, cylinder configurations and drive mechanisms are explained in detail. The design differences, operating characteristics, technological details and structural features of these configurations are exam-ined. The advantages and disadvantages of all these different structures in terms of design, production, cost, power, efficiency, friction, wear, sealing, weight, dead volume, noise and number of parts are stated. © 2023, Hamit Solmaz. All rights reserved
Effect of Clutch Pedal Distances on Fuel Consumption Under Actual Operating Conditions
No full textClutch systems are the auxiliary system for transmitting the power and torque obtained in the internal combustion engine to the gearbox, starting the vehicle, and providing gear changes. The different use of the clutch pedal directly affects the performance and fuel consumption of the vehicle. Research on fuel economy, performance, etc., in vehicles, is costly and time-consuming. In the studies conducted by researchers on braking and gearbox, experimental test equipment that allows the vehicle to operate in many different parameters and instantaneously control fuel consumption has been used. The studies have generally focused on braking and gearbox-related studies. This study investigates fuel consumption values at different pressing distances of the clutch pedal. In the experiments, with the engine at a constant speed of 3000 1/min and the gearbox in second gear, the fuel consumption at 0-20-40-60% depressions of the clutch pedal were measured. According to the data, fuel consumption values increased with increased clutch pedal depressing distance. © 2023, Hamit Solmaz. All rights reserved
Investigation of the Effects of CNC Tool Runout on Machining of 1.2379 Steel and Tool Life
No full textIn the study, the effects of tool run-out caused by the CNC spindle mechanism on surface roughness, measurement accuracy, consumable expenses, maintenance costs and cutting tool life that may occur during the cutting process wer e investigated based on metal die manufacturing. Before starting the experimental studies, the machine spindle health was measured. Here, tool pulling force, 300 mm test bar run-out, inner conical run-out and spindle vibration values were examined and evaluated. According to the results obtained, the m3/life relationship was compared with the surfa ce milling operation by eliminating the factors causing tool run-out before and after machine tool maintenance for cut ting tool life. In order to examine the effect of run-out on surface roughness and measurement accuracy, the effect of run-out was examined and compared by applying outer contour and inner contour operations before and after mainte nance with experimental studies. These operations were examined with 1.2379 steel, which is the most commonly use d steel type in the metal die sector in terms of mechanical properties. The results showed that run-out has serious ne gative effects on the cutting process and cutting tool life, measurement accuracy and surface roughness. In operations performed with a healthy spindle after maintenance, the cutting tool life increased by an average of 40%, surface rou ghness and dimensional accuracy reached the desired levels. The stress during the machine operation decreased by an average of 15%. © 2024, Hamit Solmaz. All rights reserved.(ARGE-2022-28 2201100000
Experimental investigation and optimization of HCCI engine fueled by isopropanol and heptane mixture
No full textNowadays optimization is increasing in experiments on the engine tests studies. In this study, the test fuel obtained by mixing isopropanol with n-heptane fuel under various engine conditions in HCCI mode was examined combustion, performance and emissions. The study was carried out both experimentally and statistically. Set as engine parameters, different engine speed, test fuel with isopropanol (IP20-IP40) and excess air ratio for experimental study. Engine speed is 800 rpm-1200 rpm, excess air ratio is 1.6 and 2.8, and isopropanol ratio in test fuel of 20% and 40%. From the experiment, investigations were made on effective torque, indicated mean effective pressure, indicated thermal efficiency, maximum pressure increase rate, start of combustion (SOC), combustion duration, COVIMEP, HC, CO and NOx. Before the experiments, experimental series were determined with Response Surface Method, Central Compound Design matrix. Experiments were carried out with the experimental series obtained and the data were analysed. Counter charts, ANOVA results and quartic models were obtained by entering the combustion, performance and output of the HCCI engine into the RSM interface. Then, the targeted response parameters were entered and optimization was made to determine the optimum input parameter. Response parameters under optimum operating conditions Effective Torque 11.438 Nm, IMEP 4.366 bar, MPRR 2.747 bar/°CA, COVIMEP 4.364%, CA10 2.315 °CA, CA50 7 °CA, CA10CA90 36.245 °CA, UHCs 324.562 ppm, CO 0.0118% and NOx 2.549 ppm were determined. © 2021, Hamit Solmaz. All rights reserved
Effects of CNC Tool Runouts on Drilling Process
Full text linkIn this study, the surface roughness, dimensional accuracy and tool life that tool runout caused by CNC spindle mechanism based on metal mold manufacturing were investigated. In order to understand tool runout, spindle health measurement was performed: runout measurement with 300 mm test bar, spindle conical runout measurement, spindle pull force measurement and again spindle bearing vibration values were examined. In this study, spindle maintenance was performed and its effects on the final product before and after maintenance were investigated. Holes were drilled with 1, 2 and 3 times the drill diameter, the dimensional accuracy of the holes, the effect of runout on surface roughness in the hole drilling process and the runout and life of the drill bit used were investigated. The effects of runout before and after the maintenance were compared. Elimination of tool runout positively affected the surface roughness and parts with lower surface roughness were obtained. It positively affected the dimensional accuracy and the measurement tolerance was narrowed. Since the effect of tool runout on the cutting tool life is eliminated, its life is extended and the consumable cost is reduced. It has been observed that tool runout has a negative effect on machining in the hole drilling process with this experimental study. © 2024, Hamit Solmaz. All rights reserved.(ARGE-2022-28 2201100000
The Effect of Welding Wire Feed Speed on Weld Bead Penetration, Length and Width in Robotic Gas Metal Arc Welding
Full text linkIn this study, the effect of welding wire feed speed on penetration quality in the gas metal arc welding method (GMAW), which is widely used in the automotive industry, was investigated in terms of product safety and quality. In the gas metal arc welding robots used in automotive production, the welding process is carried out through communication between the robot and the gas metal arc welding machine within predetermined parameters. In the study, 3 mm thick 6224 ERD steel was used and overlap welding was applied for experimental analysis. Among the gas metal arc welding parameters, welding current, wire diameter, and gas flow rate were kept constant, while wire feed speed was considered as the only variable. Starting from 2 m/min, the welding wire feed speed was increased by 2 m/min in each test, reaching up to 12 m/min, resulting in a total of 6 different experiments. The test results were evaluated based on metallographic analyses to determine the macro and microstructures of the welds. According to the findings, it was observed that penetration increased as the welding wire feed speed increased. However, it was also determined that beyond a certain optimum value, the increased welding speed had a negative effect on weld bead width and length. Accordingly, the optimum welding wire feed speed was suggested for achieving the appropriate penetration and maintaining weld quality. © 2025, Hamit Solmaz. All rights reserved.(ARGE-2024-042 24ARG00002
Investigation of the Use of Fuel Cell Hybrid Systems for Different Purposes
Full text linkWith 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. © 2023, Hamit Solmaz. All rights reserved
Quarter Car Active Suspension System Control Using Fuzzy Controller
Full text linkThe performance of active suspension systems is directly related to the mechanical design and control of the system. The stable operation of the controller improves driving comfort and handling. The quarter car model is frequently used in the analysis of suspension systems due to its simple structure. In this study, Matlab Simulink software was used in the modeling, control and simulation of the quarter car active suspension model. System performance was investigated for four different road profiles with PID and fuzzy logic control methods. Two of the road profiles used are in the form of impact signals consisting of pits and bumps. The other two road profiles are random road disturbances with high frequency. The effects of active and passive suspension systems on driving comfort are compared by taking into account the control methods used. As a result of the study, it has been determined that the fuzzy logic controller gives better results in pulse signals consisting of bumps and pits, and the PID controller gives better results in high-frequency random road disturbances. In addition, with the use of fuzzy logic control method in the active suspension system, a significant decrease in the actuator force has occurred. This result is very interesting in terms of minimizing energy, reducing actuator sizes and reducing costs. © 2022, Hamit Solmaz. All rights reserved
Response Surface Method Based Optimization of the Viscosity of Waste Cooking Oil Biodiesel
Full text linkIn this study, biodiesel fuel production from waste sunflower oil and viscosity optimization was carried out. During the production process, catalyst ratio, alcohol ratio and reaction temperature were determined as variable parameters. Transesferication method was used as the production method. During the production process, the use of NaOH catalyst and methyl alcohol was provided. Biodiesel production steps with the transesterification method were discussed in detail. A total of 27 different biodiesel fuels were obtained with a catalyst ratio varying between 0.03% and 0.07%, alcohol content between 15% and 25%, and reaction temperature between 50 ° C and 70 ° C. All biodiesel fuels were analyzed and their characteristics were determined. In the optimization process, catalyst ratio, temperature and alcohol ratio were considered as input parameters, and viscosity as output parameters.Both 3D surface plots and 2D contour plots were developed using MINITAB 19 to predict optimum biodiesel viscosity. To predict biodiesel viscosity a quadratic model was created and it showed an R2 of 0.95 indicating satisfactory of the model. Minimum biodiesel viscosity of 4.37 was obtained at a temperature of 60, NaOH catalyst concentration of 0.07% and an alcohol ratio of 25%. At these reaction conditions, the predicted biodiesel viscosity was 4.247. These results demonstrate reliable prediction of the viscosity by Response surface methodology(RSM). © 2021, Hamit Solmaz. All rights reserved
Working Fluid Selection and Performance Analysis for the Afyon Geothermal Energy Plant
No full textRenewable energy production has been steadily increasing in recent years. Generating energy from renewable sources and making them operational for use is essential. Alongside production, efficiently utilizing these resources is equally important. For efficient use, exploring various alternatives and conducting optimization processes are crucial. Organic Rankine Cycles (ORCs) allow energy production from low-enthalpy temperature sources. By using working fluids with low boiling points, it is possible to create a Rankine cycle at low temperatures. Each system operates under unique regional and environmental conditions, so careful selection of working fluids is necessary. Factors such as heat source temperature and pressure, ambient pressure and temperature, location, and purpose of use cause different fluids to exhibit varying behaviors. In this study, the effects of different working fluids were examined for the Afyon geothermal power plant. The active plant utilizes geothermal water at 110°C and a flow rate of 150 kg/s. The plant's capacity is approximately 2.7 MW. R-134a, a widely used working fluid, serves as the intermediary fluid. Additionally, fluids such as isopentane, n-pentane, isobutane, R-12, and R-32 were tested. Thermodynamic and thermoeconomic analyses of the system were conducted using these fluids. With R-134a, 2.75 MW of power was generated at a unit energy cost of 0.016/kWh. The energy efficiencies of the system for R-134a and isobutane were 10.9% and 11.6%, respectively. Similarly, the exergy efficiencies for these fluids were 31.1% and 33.1%, respectively. Although better results can be achieved with certain alternative fluids, the data are insufficient to directly replace the current working fluid in the system. Performing a separate optimization study with these promising fluids will be a critical step in determining the final working fluid. © 2025, Hamit Solmaz. All rights reserved
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