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    EXPERIMENTAL INVESTIGATION OF THE EFFECT OF BORON-CONTAINING NANOFLUID ON HEAT PIPE THERMAL PERFORMANCE
    (Begell House Inc, 2025) Guru, Metin; Karakaya, Ugur; Alici, Doga Sahin; Olgun, Seyma; Aydin, Duygu Yilmaz
    This study examined the effects of boron nanofluid on the performance of a two-phase closed thermosyphon heat pipe. The boron nanofluid was prepared via a two-step method, using deionized water as the base fluid and boron nanoparticles at mass concentrations of 0.5%, 1%, and 2%. Alkyl polyglycoside was added as a surfactant at a constant 0.5% by mass. Thermophysical property analysis of the nanofluid showed that the boron-containing nanofluid displayed superior thermal properties compared to deionized water. Heat pipe tests were conducted at heating powers of 200 300 W, and 400 W, with cooling water flow rates of 5 g/s, 7.5 g/s, and 10 g/s in the evaporator section. Temperature distributions in the evaporator and condenser sections were tracked using 8 K-type thermocouples. To evaluate the effect of nanoparticles on thermal efficiency, tests were conducted with both deionized water and nanofluid suspensions. Results showed a 20% efficiency increase with 2% boron nanofluid at 400 W heating power and a cooling water mass flow rate of 10 g/s. The highest observed improvement in thermal resistance due to boron nanofluid was 28%.
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    Investigation of synthesis parameters of antimony fluoroborate and its usability as a flame retardant for cellulosic fabrics
    (Editura Academiei Romane, 2021) Aydın Yılmaz, Duygu; Guru, Metin; Akkurt, Fatih
    In this study, the synthesis parameters of antimony fluoroborate, one of the metal fluoroborates, from antimony trioxide and fluoroboric acid by the wet method, and its usability as flame retardant for cellulosic fabrics have been investigated. The maximum reaction yield was determined depending on the mole ratio of reactants, temperature and stirring speed. The characterization of the product was performed by XRD and FTIR analyses. Antimony fluoroborate was produced with 94% yield at a mole ratio of reactants (nHBF(4)/nSb(2)O(3)) of 6:1, at 70 degrees C and 300 rpm. The thermal behaviors of untreated fabric and fabric impregnated with antimony fluoroborate solution were analyzed by TGA. The flame retardancy performance of antimony fluoroborate for cellulosic fabrics was determined by the vertical flame test and the limiting oxygen index (LOI) test methods. The results show that impregnating cellulosic fabrics with antimony fluoroborate enhances their thermal stability and flame retardancy.
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    Synthesis of Zinc Fluoroborate by Wet Method and Its Application as a Flame Retardant for Cotton Fabrics
    (Academic Publication Council, 2023) Aydin, Duygu Yilmaz; Guru, Metin
    In this study, zinc fluoroborate was synthesized by wet method using fluoroboric acid and zinc oxide as reactants, and its usability as a flame retardant for cotton fabrics was investigated. The wet method is economical, green, efficient, and applicable on a large scale. The maximum yield was related to the variation of reactant ratio, temperature, reaction time, and stirring rate. The product was characterized using Fourier-transform infrared spectroscopy, BF4-ion-selective electrode, and X-ray diffraction. The maximum yield of 97% was achieved at the reactant mole ratio (nZnO/nHBF4) of 1:3, temperature of 90 degrees C, and reaction time of 90 min. The purity of the synthesized product was 98%. Flame retardancy and high-temperature resistance effects of zinc fluoroborate on cotton fabrics were investigated using the limiting oxygen index (LOI) and high-temperature durability tests, respectively. Although the LOI value of the untreated original fabric was 16, this value increased to >55 upon impregnating the fabric with 50% zinc fluoroborate solution.
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    The effects of particle mass fraction and static magnetic field on the thermal performance of NiFe2O4 nanofluid in a heat pipe
    (Elsevier France-Editions Scientifiques Medicales Elsevier, 2023) Aydin, Duygu Yilmaz; Aydin, Emrullah; Guru, Metin
    In this study, experimental investigations are performed in order to determine the thermal performance of NiFe(2)O(4 )nanoparticles dispersed in deionized water in a thermosyphon-type heat pipe. The effects of the magnetic flux density and nanoparticle mass fraction were analyzed at different heat inputs and cooling water flow rates. The magnetic field was generated by the current-carrying solenoid. Our results indicated that the use of NiFe2O4 nanofluid significantly improves the thermal performance of the heat pipe which also showed that the enhancement of heat transfer coefficient can be obtained with increasing mass fraction and in presence of a low parallel magnetic field. A decrease of 26.6% was achieved in the temperature difference between the evaporator and the condenser regions compared to distilled water at a 3% mass fraction and under a magnetic field. The maximum improvement in heat pipe's thermal resistance was found as 30.4%, through NiFe(2)O(4 )nanofluid usage under magnetic field. Compared to base fluid, the application of magnetic nanofluid and parallel magnetic field reduces the thermal resistance, increases heat pipe efficiency and the heat transfer coefficient.
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    The Impacts of Nanoparticle Concentration and Surfactant Type on Thermal Performance of A Thermosyphon Heat Pipe Working With Bauxite Nanofluid
    (Taylor & Francis Inc, 2021) Yilmaz Aydin, Duygu; Ciftci, Erdem; Guru, Metin; Sozen, Adnan
    Heat pipes are one of the most preferred equipment because they have a variety of superior specifications. In this paper, the improvement of heat transfer properties of a thermosyphon heat pipe that was filled with bauxite nanofluid was experimentally investigated for different nanoparticle concentrations (1%, 2%, and 4%) and surfactant types (Triton X-100 and Sodium Dodecyl Benzene Sulfonate). Bauxite nanoparticles at different concentrations were utilized for the preparation of nanofluid suspensions. Different kinds of surfactants were also doped into the prepared nanofluid suspensions to show off how a surfactant affects the thermophysical properties of the nanofluid. The experiments were done under several heating powers and various mass flow rates of the cooling water circulating on the evaporator section. Temperature distributions both upon the evaporator and the condenser sections were recorded via 8 different K type thermocouples. Cooling water inlet and exit temperatures were also recorded and utilized for theoretical calculations. For doing an experimental comparison, thermal efficiency and resistance of the thermosyphon heat pipe were determined both for distilled water and prepared nanofluid suspensions. Moreover, contact angle-wettability analysis was carried out to determine how nanoparticles affect the surface tension. The encountered problems during the tests were addressed and discussed. The obtained experimental data illustrated that the thermosyphon heat pipe efficiency was increased by up to 20.9% with the usage of a 2% (mass) concentration of bauxite nanofluid and an anionic surfactant. The maximum enhancement in heat pipe's thermal resistance was found as 24.3%, through bauxite nanofluid usage.