Browsing by Author "Bektas, A"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Applicability of cogeneration system in gas turbines used in natural gas storage facilities
    Türkoglu, S; Yurddas, A; Bektas, A
    Underground natural gas storage facilities are of critical importance on energy supply security. Storage activity in facilities performing underground storage is mostly carried out in spent natural reservoirs. In this study, the applicability of cogeneration system was investigated in order to generate electricity from flue gas at an average temperature of 500 degrees C and 144.4 t/h flow rate obtained from three gas turbines in storage facilities and to recover the waste heat we lost. This designed system would have three HRSGs and one steam turbine, 16.23 MW energy would be generated from each HRSG in this system. After a total of 48.70 MW energy, obtained from two HGRSs, enters into the steam turbine operating in 24% efficiency, 12.20 MW mechanic energy and 11.84 MW electric energy is generated. Therefore, a total of 97.05 MW energy entering into combined cycle power plant was transformed into a total of 42.25 MW useful energy, including 30.41 MW mechanical and 11.84 MW electricity, and the efficiency of system was calculated as 43.5%. It was aimed that the electric energy to be generated from this cogeneration system would contribute to the related facility and the electricity supply of the public against its price. [Received: October 17, 2020; Accepted: May 03, 2021]
  • No Thumbnail Available
    Item
    The effects of the use of hybrid and mono nanofluids on thermal performance in flat-plate solar collectors
    Yurddas, A; Cerçi, Y; Cavdar, PS; Bektas, A
    Since considerable amount of energy is spent in water heating processes in the world, solar energy systems are of great importance while heating water. Amongst these systems, flat-plate solar collector systems have an extensive area of use in residences. Therefore, nanofluid system has been investigated in order to enhance the efficiency in water heating through flat plate solar collectors and to benefit from solar energy more effectively. A simplified model has been taken into consideration to design the model of this system and complete the analyzes more rapidly. To identify the accurateness of the model, comparisons have been made against an experimental and a numerical study; and, a decent convergence to the experimental data has been obtained. Nanofluids used in the system have been applied in hybrid structure. The analysis has been conducted for the case of that two different nanometer-sized metal nanoparticles (SiO2 and Cu) are mixed in water-based base fluid with different volume concentrations. Influences of nanofluids in different volume fractions on thermal performance have been investigated and compared against water and each other. In the system having 30 degrees angle, diversified flow rates and heat fluxes have also been evaluated. It is concluded that water-based nanofluids enhances thermal performance; and, amongst these, the nanofluid including Cu nanoparticles augments thermal performance much better. To avoid precipitation problems within the system, thermal performance has been increased by virtue of using nanofluids with lower volumetric concentrations in hybrid form by adding certain amount of Cu nanoparticle instead of using high volumetric concentrations of SiO2 nanoparticles. In comparison to water, these nanofluids we utilized have increased thermal performance in the rates of 2.03% (2%SiO2 + 1%Cu-H2O), 3.218% (1%SiO2 + 2%Cu-H2O), 0.943% (3%SiO2-H2O), 4.076% (3%Cu-H2O), 4.083% (3%SiO2 + 2%Cu-H2O), 4.935% (2%SiO2 + 3%Cu-H2O), 1.569% (5%SiO2-H2O), and 6.508% (5%Cu-H2O).