Yazar "Sara, Osman Nuri" seçeneğine göre listele

Listeleniyor 1 - 8 / 8
  • Küçük Resim Yok
    Öğe
    Density, viscosity and excess properties of binary mixtures of ethylene glycol and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide
    (Elsevier, 2022) Altun, Aycan; Sara, Osman Nuri
    Densities and viscosities of binary mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [bmim][NTf2], with ethylene glycol (EG) were measured at atmospheric pressure and from 293.15 K to 338.15 K with a step increment of 5 K. A first-order polynomial and Vogel-FulcherTammann (VFT) equation were described using experimental values to estimate the densities and viscosities of the mixtures, respectively. The excess molar volume, viscosity, and Gibbs energy of activation for viscous flow have been calculated and fitted to the Redlich-Kister equation. Besides, the thermal expansion coefficients and partial and apparent molar volumes of [bmim][NTf2] and EG in their binary mixtures have been reported. (C) 2022 Elsevier B.V. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Effect of Al2O3 Nanoparticle Dispersion on the Thermophysical Properties of [EMIM][EtSO4] Ionic Liquid
    (Springer/Plenum Publishers, 2023) Altun, Aycan; Doruk, Semahat; Sara, Osman Nuri
    In recent years, nanofluids obtained using nanoparticles and ionic liquids as base fluids have been examined under the title ionanofluids. In the present work, density, viscosity, and specific heat of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM][EtSO4], and [EMIM][EtSO4]-based ionanofluids prepared with Al2O3 nanoparticles have been measured at atmospheric pressure and from 293.15 K to 343.15 K with a 5 K step increment. It is observed that the experimental results for density, viscosity, and heat capacity of prepared ionanofluids do not match the results obtained from the classical equations used to estimate these properties. A temperature-dependent first-order polynomial is described to estimate the density of nanofluids, while a new relative viscosity model, which is a second-order polynomial including particle ratio parameter, is fitted to experimental viscosity data. Besides, hysteresis loops of the nanofluids have been investigated. The heat capacity values of the nanofluids with volume fractions of 0.16 %, 0.32 %, and 0.96 % Al2O3 are obtained to be higher than those of the pure ionic liquid, whereas the heat capacity values of the nanofluid prepared with 1.62 % and 2.65 % Al2O3 are lower.
  • Küçük Resim Yok
    Öğe
    Energy correlation of heat transfer for drag reduction surfactant solution in a double pipe heat exchanger
    (Springer, 2024) Ramamonjisoa, Bon A. A.; Altun, Aycan; Sara, Osman Nuri
    In the present study, the effects of surfactant solutions on pressure drop properties and heat transfer characteristics in a double pipe heat exchanger have been investigated. An ionic surfactant (SDS) and two nonionic surfactants (NP-10 and Tween 80) solutions with 0.2 wt% are utilized at different flow rates. The results show that pressure drops for surfactant solutions are lower than those for water at equivalent flow rates. NP-10 demonstrates high drag reduction values, reaching a maximum of approximately 15%, whereas Tween 80 has lower drag reduction values, which vary according to the flow rate. Besides, Nusselt number for water in this study reveals a satisfactory agreement with the predictions derived from the Dittus-Boelter equation with a difference of 2.1%. While NP-10 and Tween 80 addition cause the Nusselt number to decline, SDS does not significantly alter it when compared to water. Energy correlations with high R2 values have been developed using experimental data for water and surfactant solutions. Furthermore, enhancement factors (eta), the ratio of heat transferred at constant pumping power with and without surfactant, have been calculated. The eta values vary within a range of 0.8-1.1 depending on the flow rate, and for SDS solution, these values are above 1 when the Reynolds number is in the range of 13000-25000. In the case of NP-10 and Tween 80 solution, the eta values are below 1 for the whole flow rate range.
  • Küçük Resim Yok
    Öğe
    Experimental and computational (DFT) study of a binary system of triethanolamine and ethanol at temperatures from 293.15 to 323.15 K under 101.3 kPa
    (Academic Press Ltd- Elsevier Science Ltd, 2025) Muzhaqi, Evis; Kavakli, Aycan Altun; Sara, Osman Nuri; Fellah, M. Ferdi
    In this study, the density and viscosity of binary mixtures of triethanolamine (TEA) and ethanol were measured over the entire composition range at temperatures of 293.15 and 323.15 K under a pressure of 101.3 kPa. Correlations were obtained expressing density and viscosity values as a function of temperature. Excess molar volume (VE) and viscosity deviation (Delta eta) were calculated from the measured values. These properties were further fitted to the Redlich-Kister polynomial equation. Thermodynamic parameters such as partial molar volumes, apparent molar volumes, coefficients of thermal expansion, and excess Gibbs free energy of activation for viscous flow were also determined. Moreover, activation enthalpy and entropy values for viscous flow were evaluated. The experimental results and the Density Functional Theory (DFT) calculations were used to discuss the molecular interactions for binary mixtures of TEA and ethanol. Negative values of VE and Delta eta were observed across all studied temperatures and compositions, indicating strong specific interactions between TEA and ethanol molecules. There is a distinct difference in the temperature dependence of VE and Delta eta. As the temperature increases, the VE values become increasingly negative, while the Delta eta values decrease. Both experimental results and Density Functional Theory (DFT) calculations confirm the presence of intermolecular hydrogen bonding in the binary mixtures. Furthermore, FTIR spectroscopy suggests the possible presence of intermolecular interactions between the components.
  • Küçük Resim Yok
    Öğe
    Experimental and Computational Insights into the Thermophysical Properties of Glycerol and Triethanolamine Mixtures
    (Springer/Plenum Publishers, 2026) Muzhaqi, Evis; Altun Kavakli, Aycan; Sara, Osman Nuri; Fellah, M. Ferdi
    The density and viscosity of binary mixtures of triethanolamine (TEA) and glycerol were investigated over the full composition range at temperatures from 293.15 K to 323.15 K, under atmospheric pressure. The experimentally measured density and viscosity data were correlated with temperature-dependent equations. The excess molar volume (VE) and viscosity deviation (Delta eta) were determined and fitted using the Redlich-Kister polynomial equation. In addition, thermodynamic parameters, including partial molar volumes, apparent molar volumes, and thermal expansion coefficients, were evaluated to provide further insight into the mixing behavior of the system. Negative values of VE and Delta eta were observed over the entire range of temperatures and compositions investigated, indicating the presence of strong specific interactions between TEA and glycerol molecules. These interactions were further elucidated through Density Functional Theory (DFT) calculations. The computational results are consistent with the experimental observations, providing molecular-level support for the non-ideal volumetric and viscosity behavior of the mixtures.
  • Küçük Resim Yok
    Öğe
    The effects of diethyl ether, diethylene glycol dimethyl ether, and dimethyl carbonate addition on the physical and thermodynamic properties of biodiesel
    (Springer, 2024) Osman, Sibel; Sara, Osman Nuri; Kavakli, Aycan Altun; Lungu, Mioara-Jeanina
    In the present study, density, viscosity, surface tension, and refractive indices of binary mixtures of biodiesel + diethyl ether (DEE), diethylene glycol dimethyl ether (DEGDME), and dimethyl carbonate (DMC), which are used as biodiesel additives, have been measured over the whole range of concentration from 288.15 to 323.15 K and at atmospheric pressure. The density and kinematic viscosity values of the binary mixtures, prepared with different mole fractions of DEE, DEGDME, and DMC, were compared with the limits specified by the biodiesel fuel standard (EN14214). Furthermore, experimentally measured density values were utilized to define a first-order polynomial equation for estimating the densities of the prepared binary mixtures. Excess molar volumes (VE), excess thermal expansion coefficient (alpha pE), excess Gibbs energy of activation of the viscous flow (triangle G*E), deviations in kinematic viscosity (Delta nu), surface tension (Delta sigma), and refractive index (Delta nD) values were calculated. These deviation values from ideality were adjusted to a Redlich-Kister (R-K) polynomial equation and the obtained coefficients in the equation were reported. VE values were negative for biodiesel + DEE while positive values were obtained for biodiesel + DEGDME and DMC. Moreover, the values of Delta nu were negative for all mixtures of biodiesel + DEE, DEGDME, and DMC. The obtained results were analyzed with regard to intermolecular interactions and structural effects between both similar and dissimilar molecules.
  • Küçük Resim Yok
    Öğe
    The influence of surfactant type and calcination temperature on the formation of nickel oxide nanoparticles by chemical precipitation method
    (Springer, 2025) Abdulkarim, Alaa; Kavakli, Aycan Altun; Sara, Osman Nuri
    In this study, the synthesis of NiO nanoparticles was carried out using a sequential precipitation and thermal degradation method. Nickel nitrate hexahydrate (Ni(NO3)26H2O) served as the precursor, while sodium hydroxide (NaOH) was used as the precipitating agent in a stoichiometric ratio. Various surfactants, including SDS, CTAB, Tween 80, PVP, NP-10 and PEG, were used as stabilizing agents. The obtained precipitates were calcined at different temperatures ranging from 300 to 600 degrees C. The effects of surfactant type and calcination temperature on the synthesized NiO morphology, particle size, and distribution were investigated. SEM, XRD, FT-IR, and BET analyses were used for product characterization. XRD analysis confirmed that the synthesized samples had a cubic (Fm-3 m) structure. The majority of the synthesized NiO particles have an average particle size of less than 60 nm, with nearly spherical shapes except for the CTAB-assisted sample, which also displayed rod-shaped structures. Besides, calcination temperature was found to play a critical role in tailoring particle size, surface area, and pore structure. As the calcination temperature increases, the average particle size and pore distribution increase, while the surface area decreases. The BET surface areas of NiO NPs range from 44 to 110 m2 g-1, with the highest value observed in the SDS-stabilized sample, which also has the smallest particle size. According to the BET analysis, the isotherms correspond to type IV(a) based on the hysteresis loop observed in the high relative pressure region (P/P-0) between 0.6 and 1.
  • Küçük Resim Yok
    Öğe
    Volumetric Properties and Viscosities for 1-Ethyl-3-methylimidazolium Ethyl Sulfate and Ethylene Glycol Binary Mixture from 293.15 K to 343.15 K at Atmospheric Pressure
    (Springer/Plenum Publishers, 2023) Altun, Aycan; Sara, Osman Nuri; Pekdemir, Turgay
    This study presents the results from the measurements and further analysis of densities and viscosities of pure 1-ethyl-3-methylimidazolium ethyl sulfate, EMISE, and its binary mixtures with ethylene glycol, EG, over the entire composition range. Measured at atmospheric pressure from 293.15 to 343.15 K. A first-order polynomial equation was fitted to experimental density values of the EMISE + EG binary mixtures, whereas Vogel-Fulcher-Tammann (VFT) equation was used to fit viscosity data. Volumetric and excess properties have been determined. The excess molar volumes and viscosity deviations were correlated by the Redlich-Kister polynomial equation. Additionally, several selected semi-empirical viscosity models for EMISE + EG binary mixtures were tested, and coefficients were obtained. The thermal expansion coefficients of EMISE + EG binary mixtures were calculated. The intermolecular interactions between components were discussed. The results showed that in addition to the intermolecular interactions between components, packing effects due to the molecular size caused changes in properties.