Yazar "Dagidir, Kayhan" seçeneğine göre listele

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    Energy and exergy analysis of R1234yf using instead of R134a in a vapour compression refrigeration system: an experimental study
    (Inderscience Enterprises Ltd, 2023) Bilen, Kemal; Dagidir, Kayhan; Arcaklioglu, Erol; Cansevdi, Bekir
    In this study, the refrigerant R1234yf was experimentally investigated using energy and exergy approaches in a refrigeration system, as an alternative to R134a. The effects of replacing R134a with R1234yf on the system performance were discussed without making any modifications to the system. The results indicated that the compressor power input increased by 5%, cooling capacity decreased by 10%, and the energy efficiency ratio decreased by 15% in the system using R1234yf compared to R134a. Additionally, the total exergy destruction rate and second law efficiency of the system were found to be approximately equal for both refrigerants. Therefore, it can be concluded that using R1234yf resulted in a decrease in energetic system performance, while it did not have a notable effect on exergetic performance.
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    Experimental investigation of usage of POE lubricants with Al2O3, graphene or CNT nanoparticles in a refrigeration compressor
    (Beilstein-Institut, 2023) Dagidir, Kayhan; Bilen, Kemal
    In this study, the use of nanolubricants containing Al2O3, graphene, and carbon nanotubes (CNTs) at different mass fractions in a refrigeration compressor was experimentally investigated. The required electrical power of the compressor was measured to determine the effect of the use of nanolubricants. Nanoparticles used in the preparation of nanolubricants were gradually added to the lubricant to determine the optimum nanoparticle mass fraction for each nanoparticle type. Thus, it was found that the compressor operated safely and efficiently with nanolubricants. Furthermore, the optimum mass fractions were determined to be 0.750% for Al2O3, 0.250% for graphene, and 0.250% for CNTs for operating conditions of this study. As a result, the required electrical power of the compressor decreased by 6.26, 6.82, and 5.55% with the addition of Al2O3, graphene, and CNT nanoparticles at optimum mass fractions of 0.750, 0.250, and 0.250% to the lubricant, respectively, compared to the compressor using pure oil. Moreover, density and dynamic viscosity of the nanolubricant samples used in the experiments were also measured, and their kinematic viscosity, which is an important parameter for lubricants, was calculated. It was determined that the kinematic viscosity continuously increased with increasing nanoparticle fraction. In conclusion, nanolubricants containing nanoparticles above the optimum mass fraction increase the required electrical power of the compressor. It is concluded that nanoparticle fractions should not be used above the optimum value in nanolubricant applications.
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    The effect of nanorefrigerants on performance of the vapor compression refrigeration system: a comprehensive review
    (Taylor & Francis Inc, 2022) Bilen, Kemal; Dagidir, Kayhan; Arcaklioglu, Erol
    Nowadays, most refrigeration systems are based on vapor compression refrigeration cycle. These systems have been extensively studied and improved until today, hence enhancing the performance of these systems is rather difficult. Despite this limitation, several researches are still being carried out in order to improve the performance of these systems, and the usage of nanorefrigerants in vapor compression refrigeration systems is a most promising research field. Nanorefrigerants that are mixtures of nanoparticles and pure refrigerants are new kinds of refrigerants. In this review study, the effect of nanorefrigerants on the vapor compression refrigeration system performance is presented. It is observed that the usage of nanorefrigerants in the vapor compression refrigeration systems improves the coefficient of performance up to 43.93% and 56.32% in the theoretical and experimental studies, respectively.
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    Thermodynamic analysis of usage of R134a, R1234yf, R450A, R513A and R515B in the mechanical vapor compression refrigeration system
    (Gazi Univ, Fac Engineering Architecture, 2024) Bilen, Kemal; Isik, Bilal; Dagidir, Kayhan; Arcaklioglu, Erol
    R134a, which is used as a working fluid in Vapor Compression Refrigeration Systems (VCRS), is one of the refrigerants that is planned to be discontinued the usage due to the global warming. For this reason, researchers have tended to developing alternatives to R134a. In this context, in this study, the usage of R134a and its alternatives R1234yf, R450A, R513A, and R515B refrigerants were theoretically examined with the help of a theoretical model developed in the Engineering Equation Solver (EES) program using experimental data in terms of first and second laws of thermodynamics in a mechanical vapor compression refrigeration system. Analyses were performed for constant cooling capacity at various evaporation and condensation temperatures. In this study, the effects of the refrigerant type on the compressor power, heat rejection rate from the condenser, Coefficient of Performance (COP), second law efficiency, and mass flow rate of the refrigerant were determined. In addition, the results obtained under the same conditions for R134a and its alternatives were compared. As a result, compressor power increased by 5.62% for R1234yf, 2.35% for R450A, 3.41% for R513A, and 2.88% for R515B compared to R134a. Thus, it was observed that COP decreased by 5.32% for R1234yf, 2.30% for R450A, 3.30% for R513A, and 2.80% for R515B compared to R134a. Similarly, it was observed that the second law efficiency decreased by 5.32% in case of the usage of R1234yf, 2.30% in case of the usage of R450A, 3.29% in case of the usage of R513A, and 2.80% in case of the usage of R515B compared to R134a. Hence, it has been determined that the closest refrigerant to R134a in terms of the COP and the second law efficiency is R450A.