Browsing by Author "Ozel, F"

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    ENERGY ANALYSIS OF SiC-Si3N4 @ POE AND SiC-Si3N4 @ R134a BASED COOLING SYSTEMS
    Akkaya, M; Sarilmaz, A; Menlik, T; Ozel, F
    Passive methods are preferred in cooling systems and the development of these methods is one of the most important issues in terms of energy efficiency. Improving heat transfer in cooling systems by using solid-liquid and solid-gas suspensions instead of the base fluid is a crucial passive method. The compressor in the system was operated with nanolubricants in different mass fractions, and the cooling system was filled with a hybrid nanorefrigerant. The applications of nanolubricants and nanorefrigerants, the concentration of nanoparticles as an additive material in tribological tests, their compatibility with the particle type, base fluid, and surfactant are important parameters. In this context, silicon carbide (SiC) and silicon nitride (Si3N4) nanoparticles were preferred due to their compatibility and superior tribological properties in terms of contact area and wear mechanism. The results show that the addition of nanoparticles to the compressor oil and refrigerant has a positive effect on the system performance when nanolubricant with a mass fraction of 0.34% in polyol ester (POE) and hybrid nanorefrigerant with a mass fraction of 0.055% were used. With the use of nanoparticles, the coefficient of performance (COP) of the system increased by 21.82% compared to pure POE.
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    Numerical and experimental analysis of refrigerating performance for hybrid nanolubricants with sepiolite additives
    Akkaya, M; Sarilmaz, A; Balci, S; Ozel, F
    The use of nanomaterials in various forms and compositions provides the basis for the creation of high-performance structures in their application in many heating and cooling systems. In this study, the lubrication properties of rod-shaped Sepiolite (SP) and its various carbon composites Carbon Black (CB), Multi-Walled Carbon Nanotubes (MWCNT), and reduced Graphene Oxide (rGO) were investigated for the first time in a vapor compression cooling system. The cooling heat transfer performance was compared by analyzing the rheological and thermal behaviors using nanolubricants. The best improvement in cooling Coefficient of Per-formance (COP) was obtained by using SP-rGO nanoparticles. Compared to Polyol Ester (POE), the cooling performance COP increased by 23.6 % with the addition of SP-rGO. The strategy proposed here is simple and has great potential for producing high-efficiency cooling systems. In addition, the single-phase compressor motor was modeled with Finite Element Analysis (FEA) simulation in the experimental studies, and the simulation results were reported. According to the power loss data obtained from FEA simulation results, a total power loss of 119 W is determined as core losses of 44 W, winding losses of 65 W and frictional losses of 10 W for a 1 HP single-phase compressor motor. Thus, the electrical energy efficiency of the motor is approximately 86 %.
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    Histologic and physiologic analysis of the relationship between the dorsal nerve of the penis and the corpus cavernosum on a rat model. A complementary pathway on the innervation of penile erection?
    Kozacioglu, Z; Vatansever, HS; Onal, T; Kutlu, N; Ozel, F; Gunlusoy, B; Gumus, BH
    Aim The dorsal nerve of the penis (DNP) is the terminal branch of the pudendal nerve which is responsible for the somatic innervation of the penis. This study aims to outline any direct role of the DNP in the hemodynamics of erection histologically and physiologically. Materials and Methods Fifteen Wistar albino rats were sorted into the electrical activity (n = 6), intracavernous pressure (n = 4), and control (n = 5) groups. The dorsal nerve was electrostimulated and the simultaneous changes in intracavernous pressure and smooth muscle activity were recorded. Penile tissues were collected, fixed, and sectioned, the slides were stained with either hematoxylin-eosin for morphological evaluation or using the indirect immunoperoxidase technique to analyze the distributions of eNOS, iNOS, and nNOS. Results During electrostimulation, there was a simultaneous statistically significant decrease in the electrical activity inside the corpora in electromyography and an increase in intracavernous pressure. eNOS and iNOS immunoreactivities were higher in the study group than in the control group. nNOS immunoreactivity was moderate in both study and control groups. Conclusion Some fibers in the dorsal nerve of penis continue into the corpora cavernosa through the tunica albuginea and have an active, direct role in the hemodynamic process of erection, which may be complementary to the main route of innervation.