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Öğe A review of solar based hydrogen production methods(PERGAMON-ELSEVIER SCIENCE, 2018) Yılmaz, Fatih; Balta, Mustafa Tolga; Selbaş, Reşat[Abstract Not Available]Öğe A review of solar based hydrogen production methods(PERGAMON-ELSEVIER SCIENCE, 2016) Yılmaz, Fatih; Balta, Mustafa Tolga; Selbaş, ReşatHydrogen is one of the most promising fuel options for the future and it is considered as a green energy carrier. Nowadays, hydrogen can be produced from several energy resources, including those that are renewable and non-renewable. In this context, solar energy has a significant and unique potential in renewable based hydrogen production methods. The utilization of solar energy for hydrogen production promises to be one of the most viable options to replace fossil-based hydrogen production. In this paper, various solar-based hydrogen production methods are discussed and compared in terms of their pros and cons.Öğe A study on modeling and performance assessment of a heat pump system for utilizing low temperature geothermal resources in buildings(2007) Hepbaşlı, Arif; Balta, Mustafa TolgaLow and moderate geothermal resources are found in most areas of the world. A very efficient way to heat and air-condition homes and buildings is the utilization of ground source heat pumps (GSHPs), also known as geothermal heat pump (GHPs), to obtain heat energy from low temperature geothermal resources. The present study deals with the modeling and performance evaluation of a heat pump system utilizing a low temperature geothermal resource, which is approximated to a geothermal reservoir. The system was designed, constructed and tested in Nigde University, Nigde, Turkey and has been successfully operated since 2005. Energy and exergy analysis methods were used to assess the system performance based on the experimental data. Exergy destructions (or irreversibilities) as well as energy and exergy efficiency relations were presented for each component of the heat pump unit and the whole system, while some thermodynamic parameters, such as fuel depletion ratio, relative irreversibility, productivity lack, exergetic factor and improvement potential, were investigated for the system. Energy and exergy efficiency values on a product/fuel basis were found to range from 73.9% to 73.3% and 63.3% to 51.7% at dead (reference) state temperatures varying from 0 to 25 °C for the heat pump unit and entire system, respectively. It is expected that the model presented here would be beneficial to the researchers, government administration, and engineers working in the area of heat pump systems for residential applications. © 2006 Elsevier Ltd. All rights reserved.Öğe Comparative assessment of various chlorine family thermochemical cycles for hydrogen production(Pergamon-Elsevier Science, 2016) Balta, Mustafa Tolga; Dinçer, İbrahim; Hepbaşlı, ArifThis study deals with a comparative assessment of various chlorine family cycles, namely copper chlorine (CuCl), magnesium-chlorine (MgCl), iron-chlorine (Fe-Cl) and vanadium-chlorine (V-Cl) cycles, which are driven by heat and/or electricity. Hydrogen production through thermochemical and/or hybrid cycles can play a significant role in reducing greenhouse gas emissions and hence offering opportunities for better environment and sustainability. In this paper, we conduct energy and exergy analyses of the VCl cycle and examine both energy and exergy efficiencies of the cycle. We also undertake a parametric study to investigate how the overall cycle performance is affected by changing the reference environment temperature and cycle operating conditions. The performance of VCl cycle are evaluated and compared with CuCl, MgCl and FeCl cycles. Furthermore, these cycles are discussed and compared with each other through their advantages and challenges. As a result, VCl cycle offers a good potential due to its high efficiency over 40% based on a complete reaction. In this regard, VCl cycle appears to be one of the most promising low temperature cycles. It may, therefore, compete with other low temperature cycles such as copper-chlorine. (Öğe Comparing the energetic and exergetic performances of a building heated by solar energy and ground-source (geothermal) heat pump(Trans Tech Publications, 2012) Hepbaşli, Arif; Balta, Mustafa Tolga; Alsuhaibani, Zeyad; Pan, W; Ren, JX; Li, YGIn this study, we considered a building, which had a volume of 336 m(3) and a floor area of 120 m(2), with indoor and outdoor air temperatures of 20 degrees C and 0 degrees C, respectively. For heating this building, we selected two options, namely (i) a ground-source (geothermal) heat pump system (Case 1), and (ii) a solar collector heating system (Case 2). We employed both energy and exergy analysis methods to assess their performances and compare them through energy and exergy efficiencies and sustainability index. We also investigated energy and exergy flows for this building and illustrated from the primary energy transformation through the heat production system and a distribution system to a heating system, and from there, via the indoor air, across the building envelope to the surrounding air. We calculated that the total exergy efficiencies for Cases 1 and 2 were 4.7%, and 26.1% while sustainability index values for both cases were 1.049 and 1.353 at a reference (dead) state temperature of 0 degrees C, respectively.Öğe Exergetic cost analysis and sustainability assessment of various low exergy heating systems(Elsevier Science Sa, 2012) Balta, Mustafa TolgaThis study deals with energy/exergy, exergy cost analyses and sustainability assessment of a low exergy heating system. In this study, an indoor sports hall with a volume of about 28,180 m(3) and a floor area of 2366 m(2) is considered as a case study. In this context, three different heating options are investigated, namely, (i) a conventional boiler, (ii) a condensing boiler and (iii) an air heat pump as driven by fuel-oil, natural gas and electricity, respectively. In this regard, an energy and exergy analysis is employed to assess their performances and compare them through energy and exergy efficiencies and sustainability index. Also, total exergy costs based on the considered systems with three different fuels are determined and compared with each other. Overall exergy efficiencies of the heating systems are found to be 2.10%, 2.33% and 2.42% while their corresponding sustainability index values of the analyzed cases are calculated to be 1.021, 1.024 and 1.025 for cases 1 through 3, respectively. Total exergy costs of the considered systems are obtained to be C-case1 > C-case3 > C-case2. Based on the exergy cost analysis results, the most cost effective system is Case 2. (C) 2012 Elsevier B.V. All rights reserved.Öğe Exergoeconomic analysis of a hybrid copper-chlorine cycle driven by geothermal energy for hydrogen production(Pergamon-Elsevier Science Ltd, 2011) Balta, Mustafa Tolga; Dinçer, İbrahim; Hepbaşlı, ArifIn this study, we conduct an exergy, cost, energy and mass (EXCEM) analysis of a copper-chlorine thermochemical water splitting cycle driven by geothermal energy for hydrogen production. We also investigate and illustrate the relations between thermodynamic losses and capital costs. The results show that hydrogen cost is closely and directly related to the plant capacity and also exergy efficiency. Increasing economic viability and reducing the hydrogen production costs will help these cycles play a more critical role in switching to hydrogen economy. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Thermodynamic analysis of geothermally driven high-temperature steam electrolysis system for hydrogen production(Springer International Publishing, 2014) Balta, Mustafa Tolga; Dinçer, İbrahim; Hepbaşlı, ArifHydrogen production by high-temperature steam electrolysis (HTSE) has been receiving increasing attention worldwide due to its high efficiency and carbon-free operation. Although it is still considered in its early developmental stage, it offers a promising solution for highly efficient hydrogen production. From the thermodynamic viewpoint of water decomposition, it is more advantageous to electrolyse water at high temperatures because the energy is supplied in mixed form of electricity and heat. In this study, a HTSE process coupled with and powered by a geothermal power plant is considered for analysis and assessment and as a case study. In this regard, its thermodynamic analysis through energy and exergy is conducted for performance evaluation and comparison purposes. As a result, compared to conventional water electrolysis, the operation at high temperatures reduces the electrical energy requirement for the electrolysis and also increases the efficiency.
