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Öğe Development of sustainable energy options for buildings in a sustainable society(Elsevıer Scıence Bv, 2011) Balta, M. Tolga; Dinçer, İbrahim; Hepbaşlı, ArifIn this study, a building with a volume of 392 m(3) and a net floor area of 140 m(2) is considered as a case study with the indoor and exterior air temperatures of 20 degrees C and -15 degrees C, respectively. For heating applications, seven options are studied, namely (i) electric boiler, (ii) cogeneration, (iii) biomass/wood, (iv) ground heat pump water-water (v) heat pump borehole/glycol, (vi) standard boiler and (vii) solar collector as driven by renewable and non-renewable energy sources. Energy and exergy analyses are conducted to assess their performances and compare them through energy and exergy efficiencies and sustainability index. Energy and exergy flows are studied and illustrated accordingly. Also, the energetic and exergetic renewability ratios are employed here along with sustainability index. The results show that overall exergy efficiencies of heating systems are found to be 2.8%, 5.5%, 6.0%, 6.4%, 6.1%, 5.4% and 25.3%, while the sustainability index values for the seven cases considered are calculated to be 1.029, 1.058, 1.063, 1.069, 1.065, 1.057 and 1.338 for options 1 through 7, respectively. So, solar collector-based heating system gives the highest efficiency and sustainability index values. (C) 2011 Elsevier B.V. All rights reserved.Öğe Energy and exergy analyses of hydrogen production step in boron based thermochemical cycle for hydrogen production(Pergamon-Elsevier Science Ltd, 2017) Yılmaz, Fatih; Balta, M. TolgaThis study deals with a thermodynamic assessment of hydrogen production step of the boron based thermochemical cycle. In addition, this step is assessed for its merits and demerits in terms of energetic and exergetic performances for various reference environment temperatures. In this regard, the energy and exergy efficiencies of this step are calculated as 11.00% and 20.34% and also the hydrogen production step of the cycle inlet, outlet exergy rates and exergy destruction are calculated as 1653.32 kJ/mol, 336.31 kJ/mol and 317.02 kJ/mol while the reference environment temperature is kept constant at 298 K, respectively. The technical and economic problems of the hydrogen storage and transportation find a possible solution provided that the hydrogen production step of this cycle is performed on-board of a vehicle. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Energy and exergy analyses of integrated hydrogen production system using high temperature steam electrolysis(Pergamon-Elsevier Science Ltd, 2016) Balta, M. Tolga; Kızılkan, Önder; Yılmaz, FatihIn this study, thermodynamic performance assessment of solar-driven integrated HTSE for hydrogen production is discussed in detail. The system consists of a solar tower, Brayton cycle, Rankine cycle, organic Rankine cycle (ORC) and high temperature steam electrolysis (HTSE). The required heat energy for power generation cycles are supplied from solar energy while produced electricity is used for the necessary energy demand of HTSE. For the analyses, the inlet and outlet energy and exergy rates of all subsystems are calculated and illustrated accordingly. From the results of the analyses, the overall energy and exergy efficiencies of the considered system are found to be 24.79% and 22.36% for power generation section and 87% and 88% for hydrogen production section respectively. Also it is found that without any auxiliary equipment, the considered hydrogen production process consumes 1.98 kWh(e) at 230 degrees C, generates 0.057 kg/s H-2. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Energy and exergy analyses of magnesium-chlorine (Mg-Cl) thermochemical cycle(Pergamon-Elsevier Science Ltd, 2012) Balta, M. Tolga; Dinçer, İbrahim; Hepbaşlı, ArifIn this paper, we conduct energy and exergy analyses of the magnesium-chlorine (Mg-Cl) thermochemical cycle for hydrogen production and examine the respective cycle energy and exergy efficiencies. We also undertake a parametric study to investigate how the overall cycle performance is affected by changing the reference environment temperature and operating conditions. The results show that Mg-Cl cycle offers a good potential due to its high energy and exergy efficiencies as 63.63% and 34.86%, respectively, based upon the conditions and parameters considered. In this regard, Mg-Cl cycle appears to be a promising low temperature thermochemical cycle. It may, therefore, compete with other low temperature thermochemical and hybrid cycles such as the copper-chlorine cycle. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Environmental ımpact assessment of electricity production, a case study of Turkey(Springer International Publishing Ag, 2016) Yılmaz, Fatih; Balta, M. Tolga; Selbaş, Reşat; Demiral, Doğan; Grammelis, P[Abstract Not Available]Öğe Experimental exergoeconomic assessment of a desiccant cooling system(Pergamon-Elsevier Science Ltd, 2013) Hürdoğan, Ertac; Büyükalaca, Orhan; Balta, M. Tolga; Hepbaşlı, Arif; Yılmaz, TuncayDesiccant cooling has become a well established technology in most parts of the world, especially recently in Turkey. The increased growth of the technology was caused by the contribution of refrigerants used in conventional cooling systems to the depletion of the ozone layer. This technology provides a tool to control humidity (moisture) levels in conditioned air spaces. In this study, a desiccant cooling system was designed, constructed and tested in Cukurova University, Adana, Turkey while it has been successfully operated since 2008. Exergy, cost, energy and mass (EXCEM) analysis was applied to this system for the first time to the best of the authors' knowledge. The relations between thermodynamic losses and capital costs were also parametrically investigated and illustrated in figures. Based on the overall system (OS) results, some components of the whole system, namely the electric heater unit, the expansion valve, the pump, the fresh air fan and the condenser fan were obtained to be inefficient. Particularly, the electric heater unit was important as its exergy loss rate ((R) over dot(ex)) value was 29.36 times greater than that of the OS. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Güneş enerjisi destekli organik rankine çevriminin ekserji analizi(Teknolojik Araştırmaları, 2015) Yılmaz, Fatih; Selbaş, Reşat; Balta, M. TolgaBu çalışmada güneş çanaklı organik Rankine çevriminin (ORC) enerji ve ekserji analizleri incelenmiş, çevrimde akışkan olarak R-410a kullanılmıştır. Hesaplamalar Isparta güneş enerjisi verilerine göre yapılmıştır. Sistemin türbin giriş basıncı ve kazan sıcaklığına göre verimleri incelenmiştir. Sonuçta türbin giriş basıncının ve kazan sıcaklığının artmasının sistemin ısıl verimini ve ekserji verimini artırdığı belirlenmiştir. Çevrimin ısıl verimi % 10, ekserjetik verimi ise % 70 olarak hesaplanmıştır.Öğe Performance analyses of CO2-N2O cascade system for cooling(Springer Int Publishing AG, 2016) Yılmaz, Fatih; Selbaş, Reşat; Özgür, Arif Emre; Balta, M. Tolga; Grammelis, P[Abstract Not Available]Öğe Performance assessment of solar-driven integrated Mg-Cl cycle for hydrogen production(Pergamon-Elsevier Science Ltd, 2014) Balta, M. Tolga; Dinçer, İbrahim; Hepbaşlı, ArifThe present study develops a new solar energy system integrated with a Mg-Cl thermochemical cycle for hydrogen production and analyzes it both energetically and exergetically for efficiency assessment. The solar based integrated Mg-Cl cycle system considered here consists of five subsystems, such as: (i) heliostat field subsystem, (ii) central receiver subsystem, (iii) steam generation subsystem, (iv) conventional power cycle subsystem and (v) Mg-Cl subsystem. Also, the inlet and outlet energy and exergy rates of all of subsystems are calculated and illustrated accordingly. We also undertake a parametric study to investigate how the overall system performance is affected by the reference environment temperature and operating conditions. As a result, the overall energy and exergy efficiencies of the considered system are found to be 18.18% and 19.15%, respectively. The results show that the Mg-Cl cycle has good potential and attractive overall cycle efficiencies over 50%. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
