Cooling towers are generally utilized in heating, ventilation, and air conditioning systems, electric power plants and manufacturing applications. The main problem for cooling towers is evaporation loss. The evaporation loss is decreased with utilizing fans, drift eliminators for more water saving. This work is mainly focused numerical analysis of cooling tower for reducing evaporation loss and increase the efficiency of the tower by utilizing two crosswise swirling jets that reduce the inlet hot water temperature in the outlet of the cylindrical channel to the not harmful to ambient conditions temperature. The model is computed for various parameters; air inlet temperatures (10, 22, 32, 40 °C) and Reynolds number for jets inlet velocities (Re= 3900, 5200, 7800, 8500). This model was studied numerically by utilizing ANSYS Fluent CFD software. In this work, it is achieved that increasing Reynolds number causes an increase on evaporation loss. The higher air inlet temperature causes higher evaporation loss. When the air inlet temperatures are reduced from 40 °C to 10 °C, the evaporation loss is decreased as 62% and 81%, respectively. When Reynolds number is decreased from 8500 to 3900, the evaporation loss decreased as 30%. By utilizing this new design, the outlet water temperature could be reduced of 19 °C. Moreover, the numerical findings were validated by some researches available in the literature.

Microchannel heat exchangers have been gradually getting importance in industrial applications due to offering outstanding benefits. The current study has focused on the development of a numerical model to predict the thermal performance of the microchannel air preheaters (MCPH) for HVAC systems. An experimental study has been performed to validate the numerical model results. A louvered fin multiport microchannel heat exchanger has been employed as an air preheater in the experiments. The proposed model has been developed based on the segment-by-segment approach and calculated the outlet temperature and heat capacity of the MCPH. Different air velocities at the frontal face and varying mass flow rates in passes of the MCPH have been taken into consideration in the model. It has been concluded from experimental data that the model predicts the outlet temperature with an average absolute deviation within ±2% for all investigated test conditions. The proposed model shows high accuracy with respect to temperature calculation. Another conclusion is that the non-uniform air velocity approach improves the precision of the proposed model. The heat capacity predictions with the uniform air velocity approach indicate higher deviations than the non-uniform air velocity approach.

In internal combustion engines, the use of gas fuels is becoming widespread due to its advantages such as low cost and being more environmentally friendly. Acetylene is one of the gas fuels seen as an alternative to petroleum-based fuels in internal combustion engines. In this experimental study, the availability of acetylene gas, a gas fuel, at 1600 rpm, 2400 rpm and 3200 rpm engine speeds in a spark plug-fired engine was investigated. Acetylene gas was added to gasoline by 5% and 10% of the mass and its effect on exhaust emissions was studied. The results showed that adding acetylene gas to gasoline by mass increased CO, CO2 and NOx emissions and exhaust gas temperature. HC, oxygen emissions and air supply coefficient decreased.

The piston and valve surfaces of diesel engine have been coated with Cr2O3, Cr2O3+50%Al2O3 and Cr2O3 + 75% Al2O3 ceramic powders with bond coat (NiCr) by atmosferic plasma spray (APS) method. The engine performance of the coated engine were compared with the standard engine values by using that the engines tests were applyed repeat for each specimen in an electrical dynamometer in full power 1400 rpm, 1700 rpm, 2000 rpm, 2300 rpm, 2600 rpm, 2900 rpm and 3200 rpm engine speeds. In the results; it has been seen that engine power increased from 7% to 29%, engine torque from 7% to 23%, and exhaust gas temperatures from 6% to 17%, thermal brake efficiencyfrom 2.8% to 12.7% while specific fuel consumption decreased of 2.8% to 11.5%.

In the present study, 1-dodecanethiol self-assembled monolayers (SAMs) on graphene oxide (GO) –Au (Gold) thin films as molecular templates for the selective deposition of multilayer films was performed. Thus, heterostructured GO/Au/DDT and DDT/Au/GO thin film are fabricated by sputtering Au target onto modified GO structure or self-assembled 1-dodecanethiol (DDT) arrays. It has been shown that a new device concept can be made by completing the glass substrate with the surface heterostructures; i.e. layer GO sheet or DDT with Au nanoparticles (Au NPs). In the light of the performed study, the layer-by-layer assembling of DDT on the GO sheet-Au thin films template has been proved for the distinct conjugation. Also, Optical and morphological characterizations are coherent with the instantaneous nucleation and growth model over the modified DDT-Au NPs-GO or GO-Au NPs-DDT thin films in the aspect of surface roughness, the phonon transport, and other multilayer films properties. As a consequence, the multilayer films of DDT-capped Au thin films and GO sheets have shown a better hybrid nanostructure with higher consistency, hierarchy and surface area. In addition, this work will present a new perspective for template preparation based on nanostructured thin films due to its unique properties resulting from nanoscale properties.

In automotive industry, molecular bushings transfer loads from steering gearbox to wheels on a vehicle. The pipe is one of the most vital member of these routing systems and manufactured using 41Cr4 sheet metal. For a pipe of molecular bushing, analytical solutions of crack tip plastic zone size is derived by using four yield criteria: Von Mises, Tresca, Hill48, and Hu2003. Hill48 and Hu2003 are useful criteria for materials with higher anisotropy such as sheet metals. Material’s hardening behaviour is modelled using bilinear isotropic hardening rule by coupling with associated flow rule under isotropic and large scale plasticity condition. The solutions are developed for mode-I loading case due to service conditions of the pipe. A finite element simulation is performed to collect stress intensity factors. Results are verified by comparing to those of Irwin and Dugdale. The plastic zone’s shape and size are analysed for different anisotropy cases. The results show that plastic zone have “kidney” or “butterfly” shapes depending on the yield criteria used. Increasing anisotropy has significant effect on plastic zone.

In this study, the nonlinear behavior of ductile reinforced concrete (RC) shear walls having different parameters was analytically investigated. The purpose of this study is to determine the effect of axial load, longitudinal reinforcement ratio and transverse reinforcement ratios on the moment-curvature and lateral force-lateral peak displacement relationships of RC shear walls. RC shear walls that have various parameters were designed by taking into account the regulation of the Turkish Building Earthquake Code (TBEC, 2018). By considering the nonlinear behavior of the materials, behaviors of the RC shear walls were examined within the framework of the moment-curvature relation. The moment-curvature relations of RC shear walls with different parameters were obtained with the Mander model which takes into consideration the lateral confined concrete strength for different parameters. The effects of the analyzed parameters on the nonlinear behavior of the RC shear walls were evaluated in terms of curvature ductility, moment capacity, peak displacement, the angular displacement and displacement ductility values. It was seen that changes in the transverse reinforcement, longitudinal reinforcement, and axial load levels had important influence on the moment-curvature and lateral force-lateral peak displacement behavior of the RC shear walls.

In most places with energy transmission, data of the line can be obtained with sensors. However, in recent years, the energy requirement of sensors has been met through harvesters. The electrical power required for sensor systems can be provided through electromagnetic fields around the line, especially through the electrical power transmission line or energy-carrying cable systems. In this study, numerical analysis of the harvester with toroidal coil, which was intended to be used for sensor feeds, was performed using Ansys Maxwell. In addition, experimental studies of the harvesters with toroidal core were carried out. The results were compared with some studies in the literature. Considering line current and saturation effects, it was seen that the studied toroid models were appropriate for home sensor applications.

In this paper, a new broadband patch antenna design for fifth-generation (5G) sub-6 GHz mobile systems is presented. The proposed 5G antenna has a very compact size with an overall dimension of 10.7 × 22.5 mm2. The 5G antenna consists of a log-periodic patch in the form of an equilateral triangle with a 50 ? microstrip line feed and a ground plane of rectangular shape. The prototype of the proposed 5G antenna was made by etching on an FR4 substrate with a 1.6mm thickness, 4.3 dielectric constant and 0.02 tangent loss. The 5G antenna is designed and simulated for the frequency band range of 3.4-4.2 GHz. According to the measurement results, the 5G antenna impedance band range is determined as 3.1-3.9 GHz. Besides, the proposed 5G antenna has also near-omnidirectional radiation patterns both simulation and measurement at the resonance frequencies of 3.8 GHz and 3.5 GHz, respectively. According to these results, the proposed antenna is showed similar radiation characteristics in both measured and simulated results. With all these radiation and physical properties, the proposed log-periodic patch antenna is very suitable for sub-6 GHz 5G mobile applications.

Proportional–Integral–Derivative (PID) controllers are the most widely used systems in industrial applications and in academic research regarding control engineering. In this study, the optimal PID control parameters of a liquid level control system were determined with Response Surface Methodology. Dynamic analysis was carried out on the liquid level control system to prepare the reaction curve. Accordingly, dead time, time constant and process gain values were determined as 16s, 261s and 0.842, respectively. Based on the dynamic analysis, PID parameters were calculated in accordance with the Cohen-Coon, Ziegler-Nichols, Yuwana-Seborg methods, which are the commonly used tuning methods. The Kp, tI, tD parameters were calculated as 30.77, 29.15 and 5.4 with the Cohen-Coon method, as 0.453, 30.0 and 7.5 with the Ziegler-Nichols method and as 1.63, 686.3 and 117.7 with the Yuwana-Seborg method, respectively. The PID control parameters applied for the 40cm, 50cm and 60cm set points and ISE and IAE control performance values after experiments were calculated. The Kp, tI and tD values were selected as the independent parameters, while the ISE and IAE values were chosen as the dependent variables. The numerical values of the responses for the runs in the design matrices were determined with a closed-loop PID controller with the liquid level system block diagram that was designed in MATLAB/Simulink. The simulations proposed by the trial version of Design Expert 7.0 program were performed in order and the IAE and ISE values were calculated after the simulations were processed. In this study, minimum ISE and IAE values were selected to determine the best PID parameters of a liquid level control system. The optimal PID control parameters of the liquid level system required to obtain the lowest ISE and IAE values were determined as 23.14, 28.31 and 11.50 for Kp, tI and tD, respectively.

In this study, the effect of various design parameters on the removal of the Maxilon Red GRL dye, used in textile dyeing, in continuous system adsorption column was investigated using pine sawdust that were pre-treated with sulfuric acid. In each selected study parameter, the values read at certain times for the ratio of the output water concentration to the input concentration (Ct/Ci) were recorded into the graph and the breakthrough curves were drawn. The adsorption capacity (qm) obtained under the best conditions (10 cm bed height, 6 mL/min flow rate and 100 mg/L initial concentration) selected according to breakthrough curve data is 483.32 mg/g. In the latest stage, with a 0.4 M NaOH solution, the applicability of regeneration to the adsorbent bed was examined. The results of the study showed that the adsorbing capacity of the used adsorbent continued for another even after regeneration. Furthermore, the data obtained from the breakthrough curve was adapted to the Adams-Bohart, Thomas, and Yoon-Nelson models. It was understood that compared to other models, the Thomas model was more appropriate for the identification of breakthrough curves.

In this study, biocompatible polyvinylpyrrolidone (PVP) based nanofiber production was carried out with various polymer and surfactant concentrations. Firstly; various concentrations of PVP (6, 8, 10, 12, 14, 16 wt %) polymer solutions were prepared, solution properties (conductivity, viscosity, surface tension, pH and density) were determined and nanofiber production was achieved under the optimum process parameters. 12 wt % PVP concentration was chosen as an optimum in terms of nanofiber morphology and fiber fineness. Then, polymer concentration was kept constant at 12 wt % and various concentrations of surfactant (1, 2, 3, 4, 5, 6 wt %) added into the polymer solutions. According to the solution properties and Scanning Electron Microscope (SEM) images; conductivity, viscosity and average fiber diameter increased with polymer and surfactant concentrations increasement and ultra-fine, bead free and uniform nanofibers were obtained. On the other hand, surface tension and pH values were affected by polymer concentration changing, however, surface tension decreased significantly and pH decreased slightly with the addition of surfactant to the PVP polymer solution. Moreover, the density of polymer solutions increased with both polymer solution and surfactant concentration increasement.