Energy Systems Engineering / Enerji Sistemleri Mühendisliği

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  • 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: 6
    Citation - Scopus: 8
    Thermodynamic Design, Evaluation, and Optimization of a Novel Quadruple Generation System Combined of a Fuel Cell, an Absorption Refrigeration Cycle, and an Electrolyzer
    (Wiley, 2022) Khani, Leyla; Mohammadpour, Mahsa; Mohammadpourfard, Mousa; Heris, Saeed Zeinali; Gökçen Akkurt, Gülden
    In this article, a solid oxide fuel cell system is combined with a generator absorber heat exchanger absorption refrigeration cycle and a proton exchange membrane electrolyzer unit to use most of the fuel energy and recover waste heat and material. This quadruple-generation system produces electric power, refrigeration, heating, and hydrogen from natural gas as the primary energy source for the system. The thermodynamic and environmental performances of the system are studied comprehensively to identify the effects of the key operating parameters on the system operation. The results show that as fuel cell current density increases from 2000 to 8000 A/m2; the system energy and exergy efficiencies decrease by nearly 20%, but the unit carbon dioxide emission increases by 30.38%. Also, the energy and exergy efficiencies are maximized, and the unit carbon dioxide emission is minimized at a specified value of fuel utilization factor. Additionally, increasing the steam to carbon ratio has a damaging effect on the system efficiencies but leads to higher unit carbon dioxide emission. Then, the genetic algorithm is applied to optimize the condition, so the highest exergy efficiency is attainable. The optimization results demonstrate that an exergy efficiency as high as 0.6443 is achievable.