Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2026Scopus SJRQ1Multi-parameter hydrodynamic analysis of pulsation frequency and waveform effects in a conical spouted bed: A CFD study
Çutay, Arif; Tozlu, Alperen; Kütük, Begüm; Özahi, Emrah
The hydrodynamic behavior of spouted beds is strongly influenced by inlet flow conditions, particularly under pulsating operation. In this study, a three-dimensional Eulerian–Eulerian two-fluid model coupled with the kinetic theory of granular flow was used to investigate the effects of pulsation frequency and waveform on the hydrodynamics of a conical spouted bed. Steady, sinusoidal, pulsatile, and square-wave inlet conditions were analyzed at 1, 3, 5, and 10 Hz. A multi-parameter evaluation framework was applied by combining spout height, temporal stability, axial gas and particle velocity distributions, and mixing characteristics. Spout height was determined using the connected αs=0.05 iso-contour, while temporal behavior was quantified through the mean spout height, standard deviation, coefficient of fluctuation, and fluctuation range. The results show that spout performance depends not only on instantaneous inlet velocity but also on the persistence of axial momentum transfer. Although the steady condition and some high-penetration pulsating cases produced relatively large instantaneous spout heights, they did not necessarily provide the most favorable hydrodynamic behavior because of rapid velocity decay, stronger fluctuations, or reduced structural coherence. Pulsation at 3 Hz provided the best overall balance by sustaining particle transport and improving temporal stability. The 5 Hz cases enhanced mixing but exhibited larger fluctuations, whereas the 10 Hz cases produced weaker and less coherent spout structures because of rapid attenuation of the imposed oscillations. Overall, the proposed framework demonstrates that spouting performance should be evaluated through the combined effects of penetration, stability, momentum persistence, and mixing.
AtıfOpenAlex1
İncele - MakaleYalnız künye2026Scopus SJRQ2Hydrodynamic characterization and design evaluation of a conical spout–fluidized bed under geometric and gas-distribution effects
Çutay, Arif; Tozlu, Alperen; Özahi, Emrah
Spout–fluidized beds are widely used in gas–solid processing and thermal conversion applications because of their enhanced particle circulation, mixing, and heat-transfer characteristics. However, the combined effects of reactor geometry, distributor configuration, and gas-flow distribution on the hydrodynamic organization of conical spout–fluidized beds are still not sufficiently quantified from a design perspective. In this study, a three-dimensional transient numerical analysis was performed to assess the effects of cone angle, auxiliary-hole number, and auxiliary-to-total flow-rate ratio on gas–solid flow behavior in a conical spout–fluidized bed reactor. The simulations were carried out using an Eulerian–Eulerian two-fluid model coupled with the kinetic theory of granular flow and the Syamlal–O'Brien drag model. Three cone angles (50°, 60°, and 70°), three distributor configurations with 70, 140, and 210 auxiliary holes, and two auxiliary-to-total flow-rate ratios (Qf/QT≈0.15 and Qf/QT=0.43) were investigated. The hydrodynamic response was evaluated using particle velocity, voidage distribution, and two compact flow indices: the radial spout heterogeneity index (RSHI) and the axial spout regularity index (ASRI). The results show that the flow field is governed by a characteristic core–annulus structure consisting of a dilute, high-velocity spout core and a denser recirculating annulus. Increasing Qf/QT enhances auxiliary gas penetration, particle suspension, and radial expansion of the gas-penetrated region; however, it also increases RSHI and ASRI, particularly at lower cone angles, indicating stronger radial heterogeneity and axial irregularity. Increasing the cone angle from 50° to 70° reduces radial hydrodynamic heterogeneity and improves axial spout regularity, whereas the number of auxiliary holes has a secondary and configuration-dependent influence compared with the gas-flow distribution and cone angle. Overall, the findings indicate that the auxiliary-to-total flow-rate ratio primarily controls gas distribution and gas–solid momentum exchange, while the cone angle governs radial uniformity and axial spout regularity. The proposed RSHI–ASRI framework provides a design-oriented basis for comparing conical spout–fluidized bed configurations and selecting operating conditions according to the desired balance between gas–solid interaction intensity, radial uniformity, and axial spout regularity.
- MakaleAçık Erişim2024Scopus SJRQ1District heating based on exhaust gas produced from end-of-life tires in Erzincan: Thermoeconomic analysis and optimization
Güngör, Osman; Tozlu, Alperen; Arslantürk, Cihat; Özahi, Emrah
This paper presents the thermoeconomic analysis and optimization of the Erzincan Waste Tire Recycling and Power Plant (EWTRPP) in Turkey and its waste heat-based district heating (DH) system. A thermoeconomical method, namely the specific exergy costing (SPECO), is applied to allocate cost flows through subcomponents of an actual existing plant. Besides, the obtained thermoeconomic results are improved by using an optimization method, namely non-dominant sorting genetic algorithm (NSGA-II), considering the temperature of the exhaust gas discharged to the atmosphere (T25), the thermal conductivity value of the insulation material (ki) and pipe roughness value (s). The energy and exergy efficiencies of the existing plant are found to be 27.37% and 35.57%, respectively, considering the data of the actual plant. Moreover, the energy and exergy efficiencies of the waste heat-based DH system are found to be 43.08% and 55.99%, respectively. The total cost rate of the overall system is deduced 13.98 $/hby means of SPECO method. According to the results of the NSGA-II optimization method, the exergy efficiency and total cost rate of the overall system are evaluated as 6.93% and −2.51 $/h, respectively. Furthermore, it is also proposed that 1304 dwellings can be heated owing to the DH system utilizing the existing exhaust gas.
AtıfScopus9WoS8OpenAlex7İncele - Kitap BölümüAçık Erişim2020Scopus SJRQ4An updated portrait of numerical analyses on spout-fluidized bed incineration systems
Özahi, Emrah; Çutay, Arif; Abuşoğlu, Ayşegül; Tozlu, Alperen; Ivanov, V; Trojanowska, J; Machado, J; Liaposhchenko, O; Zajac, J; Pavlenko, I
Biodegradable wastes are becoming a serious problem in terms of health and ecological balance in parallel with the increasing of local and global populations in recent years. These wastes should be disposed in both efficient and eco-friendly ways. Considering biodegradable wastes as an energy source, it is necessary to be sure that those disposal methods should be focused on energy recovery. However, the existing waste disposal methods have not reached technologically targeted lines yet. It is very important that waste-to-energy recovery systems should have high energy conversion efficiency. Nowadays, there are many current studies based on the methods of wastes incineration. One of the most significant among these systems is fluidized or spout-fluidized bed incineration system. Unfortunately, the targeted points of the technological development of these systems in view of efficient energy recovery have not been reached yet. Existing incineration systems and current studies on this issue are generally concentrated on conventional fluidized bed systems. However, there are few studies of new generation spout-fluidized bed incineration systems which increase homogeneity and prevent waste from adhering to inner wall of a combustor. This study is focused on the conducted numerical studies in this research field. The latest developments and researches on both fluidized and spout-fluidized bed incineration systems will be investigated and discussed. The remarkable results will be pointed out by using the comparison in order to identify the gaps of the scientific literature.
- MakaleYalnız künye2020Scopus SJRQ1Optimization of an adapted Kalina cycle to an actual municipal solid waste power plant by using NSGA-II method
Özahi, Emrah; Tozlu, Alperen
In this paper thermodynamic and thermoeconomic analyses and even optimization of a Kalina cycle (KC) which is adapted to an actual solid waste power plant with a 5.66 MW installed capacity are presented as an alternative solution which is utilized to produce additional power from the exhaust gas of the plant. Up to now there is almost no study related with an adapted KC to a typical municipal solid waste power plant, and also no study based on an optimization, thermodynamic and thermoeconomic analyses of such a system together. All these facts show the novelty of this study. Herein the waste heat with a temperature of 566 °C is utilized by the adapted KC. According to the analyses of the first and second law of thermodynamics on the system, it is deduced that the electricity of 954.6 kW can be produced with the exergy efficiency of 24.15%. Furthermore, this power production can be improved by using non-dominated sorting genetic algorithm method (NSGA-II) in MATLAB software program. According to the optimization study, the deviations of the net power output and the total cost rate are found to be +3.62% and −1.47 $/h, respectively for the cycle.
AtıfScopus45WoS36OpenAlex49İncele - MakaleAçık Erişim2018Scopus SJRQ1Thermodynamic and thermoeconomic analyses of an organic Rankine cycle adapted gas turbine cycle using S-CO2
Tozlu, Alperen; Özahi, Emrah; Abusoglu, Aysegul
In this study, a model of an organic Rankine cycle (ORC) adapted gas turbine cycle using supercritical CO2 (S-CO2) as working fluid is performed. Thermodynamic analyses of system are carried out using Aspen Plus and EES programs. As a result of the thermodynamic analyses, electricity production capacity, energy and exergy efficiencies of proposed system are evaluated as 1530.88 kW, 23.30 % and 59.60 %, respectively. For the thermoeconomic analysis of the system, specific exergy costing method, SPECO, is applied as widely used one among the second law based methods. Unit exergetic cost of electricity production for 1 kWh is found to be 7.28 cent and the total cost of electricity production for 1530.88 kWh is found to be 114.43 $. The annual return from the system of the ORC adapted gas turbine cycle using S-CO(2)which has total investment cost of 3,033,300 $ is evaluated as 741,146 $ taking into account the difference between the cost of electricity production and sale price of electricity. As a result of the thermoeconomic analysis, the payback period of system is found to be 4.09 years.
AtıfWoS7OpenAlex2TR Dizin3
İncele - MakaleAçık Erişim2018Scopus SJRQ1Thermoeconomic multi-objective optimization of an organic Rankine cycle (ORC) adapted to an existing solid waste power plant
Özahi, Emrah; Tozlu, Alperen; Abuşoğlu, Ayşegül
In this paper, thermodynamic and thermoeconomic analyses, and also optimization of an organic Rankine cycle (ORC) were performed. The system was adapted to an existing solid waste power plant with a 5.66 MW installed power capacity in order to produce additional power from the exhaust gas. The actual operating data of the plant were utilized during all stages of the analyses. The originality of this paper is based on the analysis of the possibility of the energy conversion of an exhaust gas with a temperature of 566 & #x000B0;C into the electricity by utilizing an ORC system in the concept of waste-to-energy. Four different working fluids: toluene, octamethyltrisiloxane (MDM), octamethyl cyclotetrasiloxane (D4) and n-decane were considered and analyzed for the current system. This is also another novelty of this study due to lack of such a study, in the open literature, that deals with an ORC utilized for a typical municipal solid waste power plant. According to the thermoeconomic analyses, toluene was found to be the optimum working fluid with the maximum power output of 584.6 kW and the exergy efficiency of 15.69%. The optimization of the cycle was performed by using the non-dominated sorting genetic algorithm method (NSGA-II) in MATLAB software environment. The optimization results were compared and the deviations of the net power output and the total cost rate were evaluated as & #x2212;5.89%, & #x2212;3.51 & #x00024;/h for toluene; 0.96%, & #x2212;3.60 & #x00024;/h for MDM; 8.45%, & #x2212;2.04 & #x00024;/h for D4 and 2.00%, & #x2212;5.54 & #x00024;/h for n-decane, respectively.
AtıfScopus87WoS80OpenAlex88İncele - MakaleYalnız künye2018Scopus SJRQ1Thermodynamic and thermoeconomic analyses of an organic Rankine cycle adapted gas turbine cycle using S-CO2 ; [Organik Rankine çevrimi entegre edilmiş S-CO2 kullanılan bir gaz türbin çevriminin termodinamik ve termoekonomik analizi]
Tozlu, Alperen; Özahi, Emrah; Abuşoğlu, Ayşegül
In this study, a model of an organic Rankine cycle (ORC) adopted gas turbine cycle using supercritical CO2 (S-CO2) as working fluid is performed. Thermodynamic analyses of a system are carried out using Aspen Plus and EES programs. As a result of thermodynamic analyses, electricity production capacity, energy and exergy efficiencies of the proposed system are evaluated as 1530.88 kW, 23.30% and 59.60%, respectively. For the thermoeconomic analysis of the system, specific exergy costing method, SPECO, is applied as widely used one among the second law based methods. Unit exergetic cost of electricity production for 1 kWh is found to be 7.28 ¢ and the total cost of electricity production for 1530.88 kWh is found to be 114.43 $. Annual return from the system of ORC adopted gas turbine cycle using S-CO2which has the total investment cost of 3,033,300 $ is evaluated as 741,146 $ taking into account the difference between the cost of electricity production and the sale price of electricity. As a result of the thermoeconomic analysis, the payback period of the system is found to be 4.09 years. Purpose: To propose a model (an organic Rankine cycle (ORC) adopted gas turbine cycle using supercritical CO2: S-CO2) for an existing solid waste power plant in the frame of the heat recovery (Waste-to-energy). Theory and Methods: Thermodynamic and thermoeconomic analyses were utilized for the proposed model in order to evaluate the energy and exergy efficiencies. Results: The energy and exergy efficiencies of the system were calculated as 23.30 % and 61.60 % respectively. 1 kWh of electricity generated from GT-ORC system is produced to 7.28 ¢. The total electricity production cost of 1530.88 kW-hours was calculated as $ 111.43. Conclusion: The total cost of the developed GT-ORC system is $ 3,033,300. The difference between the cost of electricity generated from the GT-ORC system and the cost of the electricity sales is expected to be $ 741,146 annually for the proposed GT-ORC system. As a result of this profit, the payback period of the system was calculated as 4.09 years.
AtıfScopus8İncele - MakaleYalnız künye2018Scopus SJRQ1Thermoeconomic analysis and optimization of a Re-compression supercritical CO2 cycle using waste heat of Gaziantep Municipal Solid Waste Power Plant
Tozlu, Alperen; Abuşoğlu, Ayşegül; Özahi, Emrah
This paper presents thermodynamic and thermoeconomic analyses as well as optimization of a re-compression supercritical CO2 cycle. A gas turbine cycle (GT) is adapted as a model to an existing plant to generate additional power in Gaziantep Municipal Solid Waste Power Plant (GMSWPP). The total capital cost rate and total cost rate of the GT cycle are found to be 20.47 $/h and 77.14 $/h, respectively utilizing SPECO by using the exhaust gas of 16 kg/s with 1.9 bar and 566.7 °c. The net power, the energy and exergy efficiencies, the total cost and the total capital cost rates of the GT cycle are optimized by +1.73%, +3.21%, +2.45%, −1.11% and −1.64%, respectively using NSGA-II in MATLAB in the range of 2.5≤PR≤4, 200≤P6≤216, 16≤T0≤23 and 9.1≤LMTD≤12.9. This paper provides an originality such that optimization as well as thermodynamic and thermoeconomic analyses is performed simultaneously for an existing MSW power plant, which can be stressed that there are scarce amounts of studies related on this field. Moreover, as another novelty, it can be emphasized that net power output of such like plants which have similar capacity can be improved using the developed model and NSGA-II optimization method.
AtıfScopus47WoS43OpenAlex48İncele - Proje2016Biyobozunur Katı Atık Tesislerinin Termodinamik, Termoekonomik Analiz Ve Optimizasyonları Çerçevesinde Yenilenebilir Enerji Potansiyellerinin Araştırılması Ve Sıfır Atık Yaklaşımıyla Sürdürülebilir Modellerin Geliştirilmesi
Abuşoğlu, Ayşegül; Özahi, Emrah; Tozlu, Alperen
In this study, thermodynamic and thermoeconomic analysis are performed using actual operating data of the Gaziantep Solid Waste Power Plant in Gaziantep. ASPEN Plus Engineering and Engineering Equation Solver (EES) software programs are used in order to analyze the current system thermodynamically. Energetic and exergetic efficiencies of the system are evaluated as 39.57 % and 56.29 %, respectively. Thermoeconomic analyses are performed by using "specific exergy costing" (SPECO) method and the payback period is found to be 5.82 year according to the analyses. In additition, five different scenarios are carried out for the purpose of energy recovery from the exhaust gas of the system and thermodynamic and thermoeconomic analyses of scenarios are also carried out. Scenario 2 (Electricity production using gas turbine cycle) is found to be the optimal scenario which can be integrated into the system in terms of the thermodynamic and thermoeconomic analyses. As a result of the thermodynamic analyses of scenario 2, energetic and exergetic efficiencies are found to be 47.16 % and 61.83 %, respectively. Also, 1287 kW extra power can be produced using second scenario which has a short payback period of 3.7 year. By means of these proposed scenarios and conducted analyses, the first study for solid waste power plant in Turkey is carried out in detail. This detailed study is conducted for the first time that related to solid waste power plants in Turkey with proposed scenarios and performed analyses. In addition to this, the other novelty of this study is to assess the proposed scenarios in the project for other solid waste power plants in Turkey in the frame of zero waste.