Browsing by Author "Karapekmez, Aras"

Now showing 1 - 3 of 3

Citation - WoS: 34
Citation - Scopus: 37
Development of a New Solar, Gasification and Fuel Cell Based Integrated Plant
(Elsevier, 2021) Dinçer, İbrahim; Karapekmez, Aras
Despite its shortcomings, fossil-based fuels are still utilized as the main energy source, accounting for about 80% of the world's total energy supply with about one-third of which comes from coal. However, conventional coal-fired power plants emit relatively higher amounts of greenhouse gases, and the derivatives of air pollutants, which necessitates the integration of environmentally benign technologies into the conventional power plants. In the current study, a H2–CO synthesis gas fueled solid oxide fuel cell (SOFC) is integrated to the coal-fired combined cycle along with a concentrated solar energy system for the purpose of promoting the cleaner energy applications in the fossil fuel-based power plants. The underlying motivation of the present study is to propose a novel design for a conventional coal-fired combined cycle without altering its main infrastructure to make its environmentally hazardous nature more ecofriendly. The proposed SOFC integrated coal-fired combined cycle is modeled thermodynamically for different types of coals, namely pet coke, Powder River Basin (PRB) coal, lignite and anthracite using the Engineering Equation Solver (EES) and the Ebsilon software packages. The current results show that the designed hybrid energy system provide higher performance with higher energy and exergy efficiencies ranging from 70.6% to 72.7% energetically and from 35.5% to 43.8% exergetically. In addition, carbon dioxide emissions are reduced varying between 18.31 kg/s and 30.09 kg/s depending on the selected coal type, under the assumption of 10 kg per second fuel inlet.
Citation - WoS: 27
Citation - Scopus: 28
Development of a New Integrated Energy System With Compressed Air and Heat Storage Options
(Elsevier, 2020) Javania, Nader; Dinçer, İbrahim; Karapekmez, Aras
The present study investigates a biomass driven power plant integrated with compressed air and thermal energy storage subsystems. Compressed air energy storage system exploits the pressurized air at non-peak periods to be used in peak times when there is a need for extra energy. Thermal energy storage systems including phase change material, allow the solar subsystem to operate independently in order to produce hot air when solar irradiation is insufficient. The energy stored in the present system is then supplied to both the gasifier and combustion chamber in order to achieve a higher combustion efficiency. Three different phase change materials (PCMs) are investigated and their efficiencies are comparatively evaluated. Among the considered PCMs, LiNO3 is the most suitable material for the considered system with 82% energy efficiency and 84% exergy efficiency. The current study also aims at designing a renewable energy based power plant which operates continuously through using storage subsystems and is more environmental benign compared to fossil fuel based conventional systems. In this regard, wet wood (CH1.46O0.64N0.002) with 15% moisture content is selected as a fuel instead of fossil-based fuels in order to reduce the greenhouse gas emissions and eliminate the dep endency on fossil fuels. A comprehensive thermodynamic analysis is conducted to evaluate the entropy generations, exergy destructions, and energy and exergy efficiencies. The highest overall energy and exergy efficiencies are obtained as 28.58% and 24.08% in the discharging period, respectively.
Citation - WoS: 44
Citation - Scopus: 43
Development of a Multigenerational Energy System for Clean Hydrogen Generation
(Elsevier Ltd, 2021) Dinçer, İbrahim; Karapekmez, Aras
The existing fueling options for many power plants are still dependent primarily on fossil fuel resources, which in return cause serious local and global environmental problems. Therefore, in order to reduce the detrimental effects of greenhouse gas emissions, the use of cleaner production methods has been accelerated to develop and implement environmentally- friendly energy systems. In this regard, the combination of renewable energy systems and hydrogen production methods will definitely play a crucial role in the energy sector’s transition to a carbon-free production. In order to make the use of geothermal energy cleaner and more sustainable, some obstacles need to be eliminated. Most importantly, the hydrogen sulfide emissions may cause serious concerns in public acceptance of geothermal power plants. In the current study, solar, wind and geothermal energy resources are integrated to develop an integrated renewable-based energy system with a key objective of higher environmental and system performance. The underlying motivation is to propose a model which consists of a hydrogen sulfide abatement unit and an electrolyzer to produce hydrogen from hydrogen sulfide and hence eliminites the hydrogen sulfide emissions. A detailed thermodynamic analysis is carried out using Engineering Equation solver (EES) software. In addition, the effects of key design parameters and operating conditions (such as wind inlet speed and average hourly solar radiation) are analyzed, and their effects on the system overall performance are investigated. When 60 kg/s of geothermal fluid is supplied to the designed system, assuming that the NCG composition is equal to 15%, 0.7388 kg hydrogen sulfide will be emitted and 0.0433 kg hydrogen will be produced per second. The first-law (energy) and second-law (exergy) efficiencies are found to be 52.97% and 55.69% respectively.