Teknik Bilimler Meslek Yüksekokulu Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/1629

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Citation - WoS: 8
Citation - Scopus: 9
An Experimental Performance Comparison of Newtonian and Non-Newtonian Fluids on a Centrifugal Blood Pump
(Sage Publications Ltd, 2022) Önder, Ahmet; Yapıcı, Rafet; İncebay, Ömer
The use of substitute fluid with similar rheological properties instead of blood is important due to ethical concerns and high blood volume consumption in pump performance test before clinical applications. The performance of a centrifugal blood pump with hydrodynamic journal bearing is experimentally tested using Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian aqueous xanthan gum solution of 600 ppm (XGS) as working fluids. Experiments are performed at four different rotational speeds which are 2700, 3000, 3300, and 3600 rpm; experiments using GS reach between 8.5% and 37.2% higher head curve than experiments using the XGS for every rotational speed. It was observed that as the rotational speed and flow rate increase, the head curve difference between GS and XGS decreases. This result can be attributed to the friction reduction effect when using XGS in experiments at high rotation speed and high flow rate. Moreover, due to different fluid viscosities, differences in hydraulic efficiency were observed for both fluids. This study reveals that the use of Newtonian fluids as working fluids is not sufficient to determine the actual performance of a blood pump, and the performance effects of non-Newtonian fluids are remarkably important in pump performance optimizations.
Citation - WoS: 6
Citation - Scopus: 7
Fuzzy-Based Modeling and Speed Optimization of a Centrifugal Blood Pump Using a Modified and Constrained Bees Algorithm
(Elsevier Ireland Ltd, 2022) İncebay, Ömer; Önder, Ahmet; Arif, Şen, Muhammed; Yapıcı, Rafet; Kalyoncu, Mete
Background and objective: Side effects that may occur when using blood pumps for treatment of patients are the main limitations on pump rotational speed determination. Efforts are being made to reduce side effects in both design and usage procedures. In determining the pump speed for treatment, decreasing the pressure on the main artery and preserving the valve functions are taken into consideration. In addition to these, the parameters considered for design which include pump efficiency and mechanical effects on blood cells, should also be taken into consideration. In this study, the aim is to obtain the optimum pump speed for the maximum hydraulic efficiency and minimum wall shear stresses that occur inside the pump. Methods: Blood pump modeling based on fuzzy logic is created on the hydraulic performance data of a centrifugal blood pump, whose design, CFD analysis, manufacture and experimental testing have been performed previously. Using this fuzzy logic model, the optimum pump speeds were determined using the Bees Algorithm, an intuitive optimization algorithm, in the operating range 1-7 L/min fluid flow rate. In the optimization process, the aim is to achieve minimum shear stress with maximal efficiency. Intravascular pressure limits (90-160 mm-Hg) were set as pressure constraints. Results: The optimum operating point is obtained as a 3350 rpm pump speed and a 4.35 L/min flow rate. At this operating point, CFD simulation is performed, and maximum wall shear stress was found to be 1458 Pa and its efficiency as 34.2%. Conclusions: In addition to the parameters commonly used in the pump speed optimization of blood pumps, the use of wall shear stresses and pump efficiency can provide certain improvements. © 2022
Citation - WoS: 7
Citation - Scopus: 5
Investigation on the Cost-Effective Optimal Dimensions of a Solar Chimney With the Bees Algorithm
(Springer Heidelberg, 2022) Ünal, Recep Emre; Güzel, Muhammed Hüseyin; Sen, Muhammed Arif; Köse, Faruk; Kalyoncu, Mete
Solar chimney systems which consist of three main parts (collector, chimney, turbine) are one of the main thermal methods that produce electricity using solar energy. In a solar chimney, the high-power generation that can be obtained by increasing the design dimensions can also cause ineffective high investment costs. In this study, differing from the traditional design approach, a heuristic optimization method based on the Bees Algorithm is present to obtain the optimum design parameters (the chimney and collector dimensions) that are provided the more effective solutions. It is made for 3 configurations in order to prove the accuracy of the optimization study using different algorithm parameters. By using the obtained mathematical equations and the defined non-currency investment cost unit for a traditional solar chimney, the optimum design parameters that can provide more power output with acceptable costs are investigated. Two main objectives are taken into consideration namely maximizing efficiency of solar chimney system and minimizing investment cost. In the optimization process, within the ranges determined for the decision variables, the maximum and minimum dimensions are determined as 1293.05-1330.47 m for the collector diameter, 94-99 m for the chimney diameter and 783-792 m for the chimney height. The obtained results showed that this open to develop approach proposed within the scope of the study can be useful in the optimal design of solar chimney systems.

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