Energy Systems Engineering / Enerji Sistemleri Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4752

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Author: search.filters.author.Khani, LeylaPublisher: search.filters.publisher.Elsevier

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Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Comprehensive Thermoeconomic Study of a New Solar Thermosyphon-Assisted Multigeneration System
    (Elsevier, 2023) Anamaq, Rasoul Najafi; Khani, Leyla; Mohammadpourfard, Mousa; Heris, Saeed Zeinali; Gökçen Akkurt, Gülden
    Nowadays, due to the global energy crisis, limited reservoirs of fossil fuels, and their negative environmental effects, the use of renewable energy sources and multigeneration systems have become good alternatives for conventional thermodynamic systems. One of these resources, whose technology has developed rapidly in recent years, is the use of solar energy for the simultaneous generation of various products. Therefore, in this research, a multigeneration system with several subsystems is introduced. The proposed system includes a solar energy collector to receive thermal energy, two thermal energy storage tanks, an organic Rankine cycle, and a Kalina cycle to generate electricity, a multi-effect distillation unit to produce fresh water, an electrolyzer to produce hydrogen, as well as heat recovery for hot water and hot air generation. In this multigeneration system, the cooling unit is designed with the help of a thermosyphon. The performance of the proposed system is studied from energy, exergy, environmental, and exergoeconomic viewpoints using Aspen HYSYS and EES software. The obtained results show that due to the addition of the thermosyphon unit to the refrigeration system, the exergy efficiency increases from 55.62% to 70.26%. As a result of this combination, the performance of the whole system is improved and the amount of costs are reduced. In addition, the parabolic collector system has the highest exergy destruction ratio, 39%, among the subsystems. Furthermore, the results of the exergoeconomic analysis indicate that the PEM water heater with 33.3% and the ejector with 22.7% own the highest cost destruction rates.
  • Article
    Citation - WoS: 26
    Citation - Scopus: 25
    Biomass Driven Polygeneration Systems: a Review of Recent Progress and Future Prospects
    (Elsevier, 2023) Tabriz, Zahra Hajimohammadi; Khani, Leyla; Mohammadpourfard, Mousa; Gökçen Akkurt, Gülden
    Biomass 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: 9
    Citation - Scopus: 10
    Energy 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, Gülden
    Environmental 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: 38
    Citation - Scopus: 40
    Exergoeconomic 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, Gülden
    Employing 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.