WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 1Citation - Scopus: 1Thermodynamic Re-Assessment of a Geothermal Binary Power Plant Operated in a Moderate-Temperature Geothermal Field(Inderscience, 2023) Özcan, Zeynep; Gökçen Akkurt, GüldenAn existing organic rankine cycle power plant which uses isobutane as working fluid is re-evaluated for different working fluids. The plant is first modelled by EES software; then the model is simulated for different working fluids obtaining heat transferred through the heat exchanger, net work output, energy and exergy efficiencies, and mass flowrate of the working fluid. Two parametric studies are conducted to evaluate the thermodynamic performance of the plant under a range of turbine inlet temperature (130°C–155°C) and geothermal resource temperature (152°C–161°C) for each working fluid. The study reveals that the highest cycle energy and exergy efficiencies are observed for R-152a at any geothermal resource temperature. R-152a resulted with 13.1% and 58.2% cycle energy and exergy efficiency, respectively at operation condition, whilst the lowest efficiency and net work output is calculated under n-butane presence.Article Citation - WoS: 26Citation - Scopus: 25Biomass Driven Polygeneration Systems: a Review of Recent Progress and Future Prospects(Elsevier, 2023) Tabriz, Zahra Hajimohammadi; Khani, Leyla; Mohammadpourfard, Mousa; Gökçen Akkurt, GüldenBiomass is the most widely used renewable energy source which is highly appreciated due to its high availability and non-intermittent nature. Considering problems such as reduction of fossil fuels, global warming, and emission of greenhouse gases, lack of attention to the existing situation may cause irreversible damage to the future of the planet. In addition to using renewable energy sources, improving the efficiency of systems will also be helpful. Polygeneration systems play an important role in increasing efficiency and reducing pollution. So, the use of biomass in polygeneration systems seems to be a great approach for sustainable development. Recent studies on biomass-based polygeneration systems have focused on how to use biomass and integrate diverse subsystems to achieve the best performance from energy and exergy viewpoints. The present paper reviews biomass-based systems, and the parameters affecting the performance of these systems. The literature review shows that the high exergy destruction rate in the gasifiers is the most frequent problem among recent articles. In addition, despite the advantages of anaerobic digestion process, the number of studies conducted on the use of this method for biomass conversion is small. In the end, results, limitations, and future outlooks of these systems are discussed.Article Citation - WoS: 9Citation - Scopus: 10Energy and Exergy Analysis of Combined Power, Methanol, and Light Olefin Generation System Fed With Shale Gas(Elsevier, 2022) Khani, Leyla; Tabriz, Zahra Hajimohammadi; Mohammadpourfard, Mousa; Gökçen Akkurt, GüldenEnvironmental problems and limitations of fossil fuel resources, especially crude oil, have intensified the importance of using cleaner and cheaper fuels besides enhancing energy conversion processes. Therefore, a novel power, methanol, and light olefin multi-generation system is designed and modeled in this paper. Chemical looping reforming, chemical looping combustion cycles, and Rankine power system are combined with methanol and light olefin production processes. The input fuel of the system is shale gas. The mass, energy, and exergy balance equations are applied for each system unit as a steady-state control volume to assess its thermodynamic operation. Then, the effects on the system performance of critical parameters are studied comprehensively. The results show that the necessary syngas can be supplied when 71.5% of the inlet shale gas is used in the steam reforming reactor of the chemical looping reforming cycle, and the steam to fuel ratio and carbon dioxide to fuel ratio are 0.61. Furthermore, if 31% of the produced methanol is consumed in the olefin production unit, the system energy and exergy efficiencies are achieved at 67.3% and 71.5%, respectively. In this case, the carbon dioxide flow rate is 800 kmol/hr, separated and stored in the chemical looping combustion cycle, leading to a clean thermodynamic system.Article Citation - WoS: 38Citation - Scopus: 40Exergoeconomic Analysis and Optimization of a High-Efficient Multi-Generation System Powered by Sabalan (savalan) Geothermal Power Plant Including Branched Gax Cycle and Electrolyzer Unit(Elsevier, 2022) Seiiedhoseiny, Miryasin; Khani, Leyla; Mohammadpourfard, Mousa; Gökçen Akkurt, GüldenEmploying suitable subsystems to reach high efficiency and low cost in renewable-based power plants is more crucial. The geothermal energy heat source is located in many countries, but this has never been investigated to run a multi-generation system, including a branched GAX cycle and an electrolyzer. In this path, a high-efficient multi-generation system powered by a Sabalan (Savalan) geothermal power plant consisting of a single flash cycle, a branched GAX cycle, and an electrolyzer is presented and scrutinized from thermodynamic and exergoeconomic viewpoints. In the end, a two-objective optimization, by using the Total Unit Cost of Product (TUCP) and energy efficiency as objectives, is utilized to find the optimum operating conditions. Critiques and studies of variables reveal that the produced hydrogen rate remains unchanged at 5.655 kg/h by changing the degassing value and temperature of the generator, condenser 2, and evaporator. By increasing the flash tank pressure from 5.2 bar to 7 bar, the cooling and heating loads rise about 108.4%, while the net electricity falls from 3977 kW to 3506 kW. Interestingly, the TUCP has a minimum value at the evaporator temperature of 273 K and condenser 2 temperature of 322.3 K. The optimization results indicate the values of the produced hydrogen rate and net electricity with 5.85 kg/h and 4187 kW are more than those of the base case. Also, the optimal values are 7.046 $/GJ, 36.82%, and 65.42% for the TUCP and energy and exergy efficiencies, respectively.Article Citation - WoS: 19Citation - Scopus: 20Multi-Objective Optimization of a Novel Supercritical Co2 Cycle-Based Combined Cycle for Solar Power Tower Plants Integrated With Sofc and Lng Cold Energy and Regasification(Wiley, 2022) Taheri, Muhammad Hadi; Khani, Leyla; Mohammadpourfard, Mousa; Aminfar, Habib; Gökçen Akkurt, GüldenThis study presents a new system for solar power, which is generated through a solar power tower with a molten salt cycle. To increase the consumption of energy losses, besides the closed supercritical carbon dioxide (sCO2) Brayton cycle, a liquid natural gas (LNG) open-cycle was used as a heat sink alongside a cascade organic Rankine cycle with the capability of working at low temperatures. LNG is implemented for a solid oxide fuel cell input, after cooling down the power generation systems and power generation. Besides the economic and thermodynamic analysis, destruction of exergy has been controlled and parametric studies are performed to investigate the influence of relative factors on the performance of the system. To optimize the system, a genetics algorithm has been employed by considering two reciprocal objective functions of the total cost rate and the exergy efficiency. The results of multi-objective optimization show that the optimized point has a total product cost rate of $115.3/h and an exergy efficiency of 71%. Furthermore, exergy analysis shows that the molten salt heat exchangers and the LNG heat exchangers have the maximum rates of irreversibility and must be taken into consideration as a major priority for optimization.Article Citation - WoS: 33Citation - Scopus: 41Development of a Personalized Thermal Comfort Driven Controller for Hvac Systems(Elsevier Ltd., 2021) Turhan, Cihan; Simani, Silvio; Gökçen Akkurt, GüldenIncreasing thermal comfort and reducing energy consumption are two main objectives of advanced HVAC control systems. In this study, a thermal comfort driven control (PTC-DC) algorithm was developed to improve HVAC control systems with no need of retrofitting HVAC system components. A case building located in Izmir Institute of Technology Campus-Izmir-Turkey was selected to test the developed system. First, wireless sensors were installed to the building and a mobile application was developed to monitor/collect temperature, relative humidity and thermal comfort data of an occupant. Then, the PTC-DC algorithm was developed to meet the highest occupant thermal comfort as well as saving energy. The prototypes of the controller were tested on the case building from July 3rd, 2017 to November 1st, 2018 and compared with a conventional PID controller. The results showed that the developed control algorithm and conventional controller satisfy neutral thermal comfort for 92 % and 6 % of total measurement days, respectively. From energy consumption point of view, the PTC-DC decreased energy consumption by 13.2 % compared to the conventional controller. Consequently, the PTC-DC differs from other works in the literature that the prototype of PTC-DC can be easily deployed in real environments. Moreover, the PTC-DC is low-cost and user-friendly.