Yazar "Erdinc, M. Tahir" seçeneğine göre listele

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    Effects of alternative refrigerants on the ejector dimensions for single and dual ejectors enhanced bus air conditioning system
    (Pergamon-Elsevier Science Ltd, 2023) Unal, Saban; Erdinc, M. Tahir; Akgun, Hakan; Bilgili, Mehmet
    One of the most critical criteria influencing the performance of an ejector enhanced vapor compression refrigeration system is the ejector size. R134a was chosen as the refrigerant in the majority of the research studies since it is widely used in practical applications. The use of R134a refrigerant, on the other hand, is restricted under the Kyoto Protocol due to its high global warming potential (GWP). In this study, an investigation was conducted to evaluate the differences in ejector dimensions that may occur when alternate refrigerants such as R1234yf, R1234ze(E), or R600a were used in the ejector enhanced bus air conditioning system. The cycle is analyzed thermodynamically to determine the state points. The diameters and lengths of the ejectors were determined using continuity, energy, and momentum equations. It can be observed that the kind of refrigerant has a significant impact on the size of the ejector. It is also determined that the R1234yf has the closest size to the R134a, and it can be deduced that utilizing a dual ejector decrease the overall size of the ejector, hence eliminating technical concerns in the ejector production process.
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    Influence of mixing section inlet and diffuser outlet velocities on the performance of ejector-expansion refrigeration system using zeotropic mixture
    (Elsevier, 2022) Unal, Saban; Cihan, Ertugrul; Erdinc, M. Tahir; Bilgili, Mehmet
    It is known that the performance of vapor compression cooling systems can be increased thanks to the ejector. In the literature, there are many studies on the subject, in which mathematical models of ejector-expansion cooling systems are developed. However, the refrigerant velocities at the mixing section inlet for the secondary flow (suction stream) and diffuser outlet were neglected in these studies. In the mathematical model used in this study, the velocities in both sections are considered and the system performance is calculated. The performance assessment of an ejector-expansion refrigeration system was realized in the case of using the R600a/R290 refrigerant mixture as a working fluid. Thus, the effect of zeotropic refrigerant mixtures on the system performance is also investigated, considering the refrigerant velocities at the mixing section inlet and diffuser outlet. According to the obtained results, it has been found that the cooling performance of the system that uses R600a/R290 mixture as a refrigerant is 5.8%-7% higher when the velocities at the mixing section inlet and diffuser outlet are considered compared to the neglected one. The exergy efficiency is also calculated to be around 4.6% lower when the ejector mixing section inlet and diffuser outlet velocities are neglected.
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    Öğe
    Performance improvement potential of a PV/T integrated dual-source heat pump unit with a pressure booster ejector
    (Elsevier, 2023) Erdinc, M. Tahir; Kutlu, Cagri; Unal, Saban; Aydin, Orhan; Su, Yuehong; Riffat, Saffa
    Dual-source heat pump unit can utilize the evaporation of the refrigerant at two different pressures. By adopting an ejector, high-pressure refrigerant stream can be used to lift compressor inlet pressure which results in a higher coefficient of performance (COP). This study proposes a renewable energy sourced and high-efficiency heat pump system which can be easily building integrated to offer a renewable heating solution. The system is devised on the complementation of dual thermal sources; one is air and the other one is solar, to maximize the utilization of ambient energy for highly efficient operation of heat pump. Using the advantage of the relatively lower operating temperature in the solar collector line, the thermal efficiency of the collector would be sufficient in winter. Adaptation of photovoltaics in the collector as a PV/T unit, will benefit the system from the produced electricity for further reduction of the demand from the grid. Along with the use of PV/T collector, the system can be potentially carbon neutral for larger collector areas. In this study, the performance improvement potential of a dual-sourced heat pump unit with an ejector as a booster is investigated for different locations in Turkey which presents different solar and weather profiles. The optimum collector evaporation temperatures are determined, and COP improvement potentials are discussed for different conditions. For a heating supply of 5 kW, the COP of the system can be improved by 22.6 % under 400 W/m2 and 10 degrees C ambient using 15 m2 PV/T collector. Including the electricity generated from the PV, reduction of the electricity demand from the grid can reach to 75 % for the same conditions.