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• MakaleAçık Erişim2026Scopus SJRQ1/r/bayburt/11421
  Multi-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

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• MakaleAçık Erişim2026Scopus SJRQ1/r/bayburt/11083
  A comparative study of metaheuristic algorithms for thermoeconomic optimization of an Organic Rankine Cycle

  Tayfur, Bilal; Turhal, Uğur; Tozlu, Alperen

  The efficient recovery of waste heat from biogas power plants via Organic Rankine Cycles (ORC) is essential for sustainable energy but requires satisfying conflicting thermodynamic and economic objectives. This study addresses the need for robust optimization strategies by evaluating nine recent metaheuristic algorithms to identify the most effective methods for maximizing net power while minimizing system costs. A multi-objective thermoeconomic model utilizing the specific exergy costing method was developed for a toluene-based ORC and optimized using algorithms including Dung Beetle, Snake, and NSGA-II. The optimization reduced the unit electricity cost by 9.1% (from $0.088/kWh to $0.080/kWh), with the Dung Beetle algorithm exhibiting superior convergence (Hypervolume 25.90) and the Snake algorithm demonstrating the best solution uniformity (Spread 1.54) with computational speed (0.084 s). These findings underscore that selecting algorithms based on specific exploration-exploitation characteristics is critical for achieving cost-effective and thermodynamically efficient power generation designs.

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  AtıfOpenAlex2

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• Derleme MakaleAçık Erişim2026/r/bayburt/10990
  Environmental and economic analysis of industrial waste heat recovery with hybrid heat pump application

  Kazici, Halil İbrahim; Tozlu, Alperen

  Today, increasing energy demands and environmental concerns have made energy efficiency a necessity from both economic and ecological perspectives. High energy consumption in industrial facilities increases costs and raises CO2 emissions. Therefore, waste heat recovery and the use of renewable energy are among the fundamental goals of sustainable production. Energy efficiency is important not only for reducing consumption but also for lowering greenhouse gas emissions, protecting the environment, and strengthening the economics of the business. In this context, heat pump technologies, which extract energy from low-temperature sources and make it reusable, stand out as effective, environmentally friendly, and efficient systems in both heating and cooling applications. In this study, waste heat from a cooling tower generated during the production process in an industrial facility was recovered through a water-source heat pump and integrated into the facility's heating system. The heat pump increased the heat energy by using low-temperature water and reused it in the process. During periods when the waste heat was insufficient, the system was supported by natural gas boilers, thus creating a hybrid operating model between the heat pump and the boiler. As a result of the implementation, natural gas consumption and electricity usage were significantly reduced, leading to lower energy costs and a substantial decrease in CO2 emissions, thereby providing notable environmental benefits. The findings indicate that the proposed system achieves an annual natural gas saving of 6,788,251 kWh and a net financial gain of 5,703,864 TL. Additionally, the payback period of the investment is calculated as 2.41 years, demonstrating the economic feasibility of the system. Overall, this case study highlights that the widespread adoption of hybrid heat pump systems in the industrial sector can make significant contributions to Türkiye’s energy transition and carbon emission goals.

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• MakaleYalnız künye2026Scopus SJRQ2/r/bayburt/10970
  Hydrodynamic 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.

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• MakaleYalnız künye2026Scopus SJRQ3/r/bayburt/10916
  An exergoeconomic analysis of a wastewater treatment plant: investigation and optimization of sludge drying—a case study

  Dagci, O.; Tozlu, A.; Berber, A.

  The primary parameters in wastewater treatment plant applications are pollutant removal in compliance with standards and energy costs. This study conducts exergy, exergoeconomic, and optimization analyses on the Konya Wastewater Treatment Plant to enhance its energy efficiency. All assessments of the plant were based on actual operational data. Numerical calculations were executed using Engineering Equation Solver software. Exergoeconomic analyses were performed using the Specific Cost Method, while optimization calculations employed the Net Present Value approach. Thermodynamic calculations revealed that the exergy efficiency of the biogas engine was 30.8%, which increased to 39.8% when integrated into a cogeneration system. The overall exergy efficiency of the plant was calculated to be 35.3%, which rose to 58.6% when stabilized sludge was utilized as fuel. During the optimization phase, various drying systems were evaluated, and a hybrid greenhouse-solar-panel drying system was identified as the optimal model. The analyses indicated that the total cost was minimized at the maximum dryness value (70%), suggesting that the greenhouse-type drying system could achieve regional conditions. Compared to thermal and solar energy systems, hybrid systems have been observed to offer significant advantages in first-year costs. Optimization studies reveal that hybrid systems provide 41% greater cost savings in initial investment and operational expenses compared to thermal systems, and 29% greater savings compared to solar energy systems. Meeting the system's energy demand with fossil fuels results in annual emissions of 76,850 tons of CO₂ and 1500 tons of harmful pollutants, equivalent to removing 19,000 cars from traffic or preserving 7300 hectares of forest. Significant soil and ecosystem degradation also occurs. The use of solar energy substantially reduces these environmental impacts, improving air quality and conserving natural resources.

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  AtıfScopus1·OpenAlex1

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• MakaleAçık Erişim2025Scopus SJRQ1/r/bayburt/14346
  Energy, exergy and economic optimization application of integrated dual-loop organic rankine cycle: A case of shopping mall power plant

  Topcu, Muhammed Taha; Tozlu, Alperen; Bilen, Kadir

  This paper presents a thermoeconomic analysis of the Dual-Loop Organic Rankine Cycle (DORC) integrated into the Erzurum Mall Power Plant (EMPP). The DORC system is designed to utilize waste heat at 425 degrees C and 9 kg/s, producing additional power for the existing plant. The integration of dual-loop ORC systems with different critical temperature fluids into an operational facility is analyzed. High-temperature cycles use working fluids such as Toluene, MDM (octamethylcyclotrisiloxane), n-Nonane, and n-Octane, while refrigerants R236fa, R600a, and R124 are employed in the low-temperature cycles. The designed model demonstrates that up to 11.4 % of the plant's existing capacity can be added as extra power. The Toluene/R600a combination is identified as the best fluid pair, delivering the highest total net power output (653.4 kW), the lowest total cost rate (19.18 $/h), and the highest exergy efficiency (20.18 %). Optimization of the DORC system is performed using the NSGA-II in MATLAB. For the toluene/R600a pair, the optimization results show an increase of 13.52 % in the net power output and decrease of 1.48 % in the total cost rate, which is a significant improvement over the initial results.

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  AtıfWoS3·OpenAlex1

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• MakaleAçık Erişim2024Scopus SJRQ1/r/bayburt/13069
  District 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.

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  AtıfScopus9·WoS8·OpenAlex7

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• MakaleAçık Erişim2022Scopus SJRQ3/r/bayburt/13378
  A Two-Stage ORC Integration to an Existing Fluidized Bed Sewage Sludge Incineration Plant for Power Production in the Scope of Waste-to-Energy

  Abusoglu, A.; Tozlu, A.; Anvari-Moghaddam, A.

  This paper presents the design, evaluation, and optimization of an electricity generation system based on the two-stage organic Rankine cycle (TS-ORC), which utilizes the waste heat of an existing fluidized bed sewage sludge incineration (FBSSI) facility. The facility incinerates an average of 300 tons per day of sewage sludge with a dry matter content of 22%. After the drying process, the sewage sludge is burned in a fluidized bed combustor, and exhaust gas at a temperature of about 850-900ºC is released due to the combustion. The system provides the energy required to dry the sludge from this exhaust gas. In this study, a TS-ORC is designed to be coupled to the exhaust gas flowlines discharged to the atmosphere at two different points in the FBSSI plant. The exergy efficiency of the FBSSI facility is found to be 70.5%. Three different working fluids are selected to examine the variations of thermodynamic and thermoeconomic performance parameters of the designed TS-ORC system. The highest power generation in the TS-ORC system (183.40 kW) is achieved using R1234yf as working fluid. R1234yf is also the most expensive fluid for electricity generation among the other working fluids (10.57 $/h). The least electricity generation in the TS-ORC (142.70 kW) occurs at the thermoeconomically most affordable cost with R245fa (9.35 $/h).

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  AtıfScopus2·WoS2·OpenAlex2

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• MakaleAçık Erişim2022Scopus SJRQ1/r/bayburt/13279
  Techno-economic assessment of a synthetic fuel production facility by hydrogenation of CO2 captured from biogas

  Tozlu, Alperen

  In this study, a thermodynamic and economic analysis of a synthetic fuel production facility by utilizing the hydrogenation of CO2 captured from biogas is carried out. It is aimed to produce methanol, a synthetic fuel by hydrogenation of carbon dioxide. A PEM electrolyzer driven by grid-tie solar PV modules is used to supply the hydrogen need of methanol. The CO2 is captured from biogas produced in an actual wastewater treatment plant by a water washing unit which is a method of biogas purification. The required power which is generated by PV panels, in order to produce methanol, is found to be 2923 kW. Herein, the electricity consumption of 2875 kW, which is the main part of the total electricity generation, belongs to the PEM system. As a result of the study, the daily methanol production is found to be as 1674 kg. The electricity, hydrogen and methanol production costs are found to be $ 0.043 kWh−1, $ 3.156 kg−1, and $ 0.693 kg−1, respectively. Solar availability, methanol yield from the reactor, and PEM overpotentials are significant factors effecting the product cost. The results of the study presents feasible methanol production costs with reasonable investment requirements. Moreover, the efficiency of the cogeneration plant could be increased via enriching the biogas while emissions are reduced.

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  AtıfScopus34·WoS32·OpenAlex37

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• MakaleAçık Erişim2022Scopus SJRQ2/r/bayburt/11957
  Assessment of waste-to-energy potential of ELT management: An actual case study for Erzincan

  Güngör, Osman; Tozlu, Alperen; Arslantürk, Cihat

  End-of-life tires (ELTs) and their decomposition are becoming a major environmental issue in the local region as a result of economic and technological challenges. Despite this, ELT management is gaining popularity as an advanced function for treating tires to obtain char, oil, and gas products using pyrolysis. The main goal of this article is to integrate data from an actual recycling plant with the activities of pyrolysis products and their physical properties in the literature. This article presents energy potentials and basic applications of pyrolysis products as well as advances in the current situation in ELT management in the world. Accordingly, an existing ELT management in Erzincan, Turkey is explained in detail by considering the available energy recovery and material treatment activities. In this plant, which has an installed power capacity of 12 MW, approximately 25 tons of pyrolytic oil, 10.7 tons of pyrolytic gas, 24 tons of carbon black and, 10.4 tons of steel are produced daily. The calorific values of carbon black and pyrolytic oil for the products leaving the pyrolysis plant are close to the values in the literature, which is promising. In the plant, the overall thermal efficiency of the system and the engine is found to be 26.34% and 51.24%, respectively. On the other hand, to supply additional power to the plant utilizing exhaust gas discharged to the atmosphere, some thermodynamic models can be developed; additionally, more rational values can be obtained through thermoeconomic and optimization.

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  AtıfScopus1·WoS2·OpenAlex3

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