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An exergoeconomic analysis of a wastewater treatment plant: investigation and optimization of sludge drying—a case study
(Springer, 2026) Dağcı, Oğuzhan; Tozlu, Alperen; Berber, Adnan
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 CO? 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. © The Author(s), under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University 2025.
An Experimental Study on the Determination of Minimum Fluidization Velocity
(Bayburt University, 2023) Tozlu, Alperen; Kutlar, Ahmet İhsan; Çarpınlıoğlu, Melda Özdinç
Pneumatic conveying systems are widely used in a variety of industrial settings since different types of materials can be conveyed. There are some classifications of flow modes for conveying of powders and bulk solid particles based on mean particle size, density, and inter particle cohesion forces. In this paper, three different cases which are vertical (test case 1), horizontal (test case 2) and continuous conveying test case are constructed and considered in order to determine the flow modes in pneumatic conveying systems. Seven solid particles are used with the range of 200 kg/m3 < ?blp < 2400 kg/ m3 and 150 ?m < dp < 2750 ?m in these three cases. In vertical test set-up unstable zone and fluidized dense phase is occurred, then in the horizontal test set-up slug flow and plug flow is observed and lastly plug flow and dilute phase is occurred visually in continuous conveying test case. Finally, all obtained data are considered for the classification according to flow modes in pneumatic conveying systems. The observed flow modes are considered and tabulated with respect to all test cases.
Assessment of waste-to-energy potential of ELT management: An actual case study for Erzincan
(Wiley, 2022) Gungor, Osman; Tozlu, Alperen; Arslanturk, 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.
Biyobozunur Katı Atık Tesislerinin Termodinamik, Termoekonomik Analiz Ve Optimizasyonları Çerçevesinde Yenilenebilir Enerji Potansiyellerinin Araştırılması Ve Sıfır Atık Yaklaşımıyla Sürdürülebilir Modellerin Geliştirilmesi
(2016) Özahi, Emrah; Tozlu, Alperen; Abuşoğlu, Ayşegül
Bu çalışmada, Gaziantep'te bulunan Gaziantep Katı Atıktan Enerji Üretim Tesisi'nin gerçek çalışma verileri kullanılarak termodinamik ve termoekonomik analizleri gerçekleştirilmiştir. Sistemin termodinamik analizlerin gerçekle?tirilmesi için ASPEN Plus Engineering ve Engineering Equation Solver (EES) programları kullanılmı?tır. Tesisin enerji ve ekserji verimleri sırasıyla, %39,57 ve % 56,29 olarak bulunmuştur. Termoekonomik analizler ise \"özgül ekserji maliyetlendirme\" (SPECO) yöntemi ile yapılmı? ve yapılan analizler sonucunda sistemin amortisman süresinin 5,82 yıl olduğu hesaplanmıştır. Ayrıca sistemin atık ısısının geri kazanılması amacıyla beş farklı model geliştirilmiş ve geliştirilen modellerin termodinamik ve termoekonomik analizler yapılmıştır. Yapılan tüm termodinamik ve termoekonomik analizler sonucunda model 2 (gaz türbin çevrimi ile elektrik üretimi) sisteme entegrasyonu yapılabilecek en uygun model olarak bulunmuştur. Model 2 için yapılan temodinamik analiz ile sistemin enerji verimi % 47,16 ekserji verimi ise % 61,83 olarak bulunmuştur. Bununla birlikte 2. model 3,7 yıl gibi kısa bir amortisman süresi ile sisteme fazladan 1287 kW'lık güç sağlayabilecektir. Geliştirilen modeller ve yapılan analizler ile Türkiye'de ilk defa bir katı atıktan enerji üretim tesisi için geniş kapsamda bir çalışma yapılmıştır. Ayrıca bu çalışmanın bir diğer özgün yanı ise proje kapsamında geliştirilen modellerin Türkiye'de bulunan diğer katı atıktan enerji üretim tesisleri için de sıfır atık kapsamında değerlendirilebilir olmasıdır.
A comparative thermoeconomic analysis and optimization of two different combined cycles by utilizing waste heat source of an MSWPP
(Pergamon-Elsevier Science Ltd, 2021) Ozahi, Emrah; Abusoglu, Aysegul; Tozlu, Alperen
In this paper, thermodynamic and thermoeconomic analysis as well as genetic algorithm optimization of two combined cycles, a gas turbine-organic Rankine cycle (GT-ORC) and a gas turbine-Kalina cycle (GT-KAL) are carried out. The novelty of this study is that the cycles are adapted to an actual solid waste power plant to generate additional power from the exhaust gas. Thus, the power generation capacity of the actual power plant can be raised by using the combined cycle. Due to this reason, besides the thermodynamic analysis of the cycles, thermoeconomic analyses and optimizations are also very important in order to improve the actual system capacity. The net power output of GT-ORC and GT-KAL are found to be 1.51 MW and 1.59 MW, respectively. The results obtained are seen to be reasonable when compared to the net power output of the power plant (5.66 MW). Another originality of this study is that the thermoeconomic results are improved by utilizing a multi-objective optimization method namely non-dominated sorting genetic algorithm method (NSGA-II). Thus, the two objectives, total power output and the total cost rate, at the design stage of the cycles are optimized and enhanced. Due to the optimization results, it is found that the net power output of the GT-ORC and GT-KAL are increased by 11.34% and 0.99%, respectively, while the total cost rates are decreased by 18.59% and 1.31%, respectively. GTORC with the net power output of 1.70 MW is seen to be more efficient as compared to GT-KAL which produces a net power output of 1.61 MW. However, the total and the capital cost rates of GT-ORC are found to be higher than those of GT-KAL.
Comparison of Drying Performances of Red and Green Apple Particles in a Tray Dryer
(2019) Tozlu, Alperen
The green and the red apples were selected as drying materials in order to dry in a tray dryer for this study. Theywere washed with distilled water to wipe out all contaminants that can be affected negatively the results ofexperiment and they were chopped to the same dimensions. The length, width and thickness of each apple piecewere adjusted as 65 mm, 37 mm and 12 mm, respectively. The apple particles were weighed with precisionscales and they were grouped into 50 g, 100 g and 200 g. Then the particles were placed in the tray dryer foreach set of experiments. Thereafter, drying process was carried out at different weights of red and green appleparticles (mp), drying air velocity (U) and drying temperatures (Td). Herein, the moisture content (MC) isconsidered as the significant parameter in order to express the drying performance of drying materials.Moreover, energetic efficiency and normalized moisture content are compared with the empiric equation, whichis proposed for the drying systems. The experimental study is performed with the range of 50 g ? mp ? 200 g,18 % ? MC ? 614.29 %, 0.03 ? MR ? 1, 59 oC ? Td ? 99 oC and 0.992 m/s ? U ? 1.488 m/s. The result of thisstudy is that the red apple particles have better drying performance at same conditions due to its physicalproperties when compared to green apple particles
COMPARISON OF FIVE DEVELOPED POWER CYCLES IN THE FRAME OF WASTE HEAT RECOVERY
(Necip Fazıl YILMAZ, 2021) Tozlu, Alperen; Abusoglu, Aysegul; Özahi, Emrah
A thermodynamic comparison of five developed power cycles which are gas turbine (GT), Kalina (KAL), organic Rankine (ORC), gas turbine-Kalina (GT-KAL) and gas turbine-organic Rankine (GT-ORC) fed by the waste heat of an actual power plant system in Gaziantep is presented in this paper. The waste heat has a temperature and a pressure of 566 oC and 1.9 bar, respectively. In order to compare the thermodynamic performance of the power cycles, various parametric studies were performed by using the effect of the values of the pressure ratio of the cycles, the temperature of the exhaust gas, the logarithmic mean temperature difference of the heat exchangers and the turbine inlet and the outlet pressures in the given ranges. The net power output of GT, KAL, ORC, GT-KAL and GT-ORC were found to be 1095 kW, 955 kW, 585 kW, 1508 kW and 1594 kW, respectively. The thermodynamic results showed that the GT-KAL cycle has the best thermodynamic performance in terms of energetic and exergetic efficiencies such as 19.71% and 40.53%, respectively, as well as in terms of the highest net power production of 1594 kW from the available exhaust gas.
District heating and electricity production based on biogas produced from municipal WWTPs in Turkey: A comprehensive case study
(Pergamon-Elsevier Science Ltd, 2021) Abusoglu, Aysegul; Tozlu, Alperen; Anvari-Moghaddam, Amjad
In this paper, district heating (DH) potentials of the wastewater treatment plants (WWTPs) based on their biogas, electricity, and heat productions are considered. Two district heating scenarios are developed: (i) DH Scenario I which is based on both excess biogas storage of the WWTP and exhaust gas of the cogeneration with the actual power output, (ii) DH Scenario II which is based on the exhaust gas of the cogeneration with the increased power output using all the biogas produced. In DH Scenario I, it is found that 458 dwellings can be heated via the DH system proposed considering only the waste heat of the cogeneration. In addition, the natural gas consumption of 1112 dwellings with the same annual heating load can also be met using the purified biogas. In DH Scenario II, the electricity production could be increased to 1643 kWh by burning all the biogas produced in the cogeneration plant. In this scenario, the annual heating load of 755 dwellings in Gaziantep province can be covered using the waste heat in the DH system. The payback period for the DH Scenario I is calculated as 2.5 years, while for the DH Scenario II, it is obtained as 2 years. (c) 2021 Elsevier Ltd. All rights reserved.
District heating based on exhaust gas produced from end-of-life tires in Erzincan: Thermoeconomic analysis and optimization
(Pergamon-Elsevier Science Ltd, 2024) Guengo, Osman; Tozlu, Alperen; Arslantuerk, Cihat; Oezahi, 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.
Energy, exergy and economic optimization application of integrated dual-loop organic rankine cycle: A case of shopping mall power plant
(Elsevier, 2025) 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.
Investigation of Shale Gas Reserves in The World and A Case Study for Electricity Production from Shale Gas in Turkey
(2021) Öztekin, Erman Kadir; Tozlu, Alperen
Shale gas reserves, which is globally accepted as unconventional gas resource, scattered around the world and can be used in order to meet the growing energy needs due to limited amounts of conventional resources. Since notable effort has to be put in order to investigate and drill shale gas resources the early decision has to be made carefully, especially considering the economic benefits. Several factors must be considered including the known technically recoverable shale gas amount at the selected region, current technology to drill the shale source and the amount of investment before the extraction of shale gas. In this study, global underground shale gas amount and recent discoveries as well as the potential shale gas areas in Turkey are presented. Benefits of using shale gas for electricity generation and common methods being used during shale gas extraction are studied along with gas and liquid flow mechanisms. At the end, general overview of separation and utilization of shale gas components is schematically presented. In the case study, the potential of electricity generation in the SE Anatolia region in Turkey is estimated with only using methane obtained from the shale gas purification process at the power generation step. According to the estimations, 3337.8 MW electric power may be generated for 50~55 years, at the appropriate gas engine by using 8.5 billion cubic meter shale gas annually.
Katı Atık Enerji Santralinde Gaz Motoru ile Birleştirilmiş S-CO? Döngüsünün Eksergoekonomik Değerlendirmesi
(Ankara Yıldırım Beyazıt Üniversitesi, 2025) Tozlu, Alperen; Trninic, Marta; Özahi, Emrah
Bu çalışmada, Türkiye'nin Bayburt şehrinde bulunan bir belediye katı atık termik santralinin (KAT) bir gaz motorundan süperkritik karbondioksit (S-CO?) çevrimi uygulanarak egzoz atık ısısının geri kazanımı incelenmiştir. Kurulu gücü 1450 kW olan santralde, S-CO? sisteminin entegre edilmesiyle yaklaşık %7,5 ekstra güç üretimine karşılık gelen 108,65 kW ek güç üretilebilmektedir. Santralin gerçek verileri kullanılarak termodinamik model geliştirilmiş ve sistem performansının doğru bir şekilde değerlendirilmesi sağlanmıştır. Geliştirilen çevrimin enerjetik ve ekserjetik verimlilikleri, enerji transferi ve ekserji yıkım değerleri açısından belirlenmiştir. Ayrıca, santral bileşenleri için maliyet dağılımı ve yatırım öngörüleri sağlayan Özgül Ekserji Maliyetlendirme (SPECO) yöntemi kullanılarak eksergoekonomik analizler gerçekleştirilmiştir. Sonuçlar, S-CO? çevriminin birleştirilmesinin hem enerji hem de ekserji verimliliğini artırdığını ve aynı zamanda genel ekonomik performansı da iyileştirdiğini ortaya koymaktadır. Sonuç olarak önerilen sistem, katı atık bazlı enerji üretim santrallerinde atık ısının geri kazanımı için sürdürülebilir ve etkili bir çözüm sunmaktadır.
Municipal solid waste-based district heating and electricity production: A case study
(Elsevier Sci Ltd, 2021) Tozlu, Alperen; Abusoglu, Aysegul; Ozahi, Emrah; Anvari-Moghaddam, Amjad
In this paper, municipal solid waste (MSW) based electricity production and district heating (DH) potential of Turkey are considered. Three MSW based waste-to-energy (WtE) scenarios is developed: (i) Scenario-I, a DH system integrated into a gas turbine power plant (GTPP), (ii) Scenario-II, a DH system integrated into an organic Rankine cycle (ORC), and (iii) Scenario-III, which is based solely on a DH system. As a result of the thermodynamic and thermoeconomic analyzes of these developed scenarios using an existing MSW-based cogeneration facility's actual operating data, the system with the most extended payback period (about 5 years) is found as the GTPP-DH system developed in Scenario-I, which also has the highest investment cost. On the other hand, the system with the shortest payback period (about 2 years) is found as the DH system developed in Scenario-III, which also has the lowest investment cost. Overall exergy efficiencies of the GTTP-DH, ORC-DH, and DH systems are found to be 41.86%, 16.15%, and 31.87%, respectively. When the developed WtE scenarios adapted to the pilot provinces selected from each geographical region of Turkey, it is found that the GTPP system developed in Scenario-I can increase the power generation capacity of MSW plants for each province by about 20%. (C) 2021 Elsevier Ltd. All rights reserved.
Optimization of an adapted Kalina cycle to an actual municipal solid waste power plant by using NSGA-II method
(Pergamon-Elsevier Science Ltd, 2020) Ozahi, 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 degrees 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. (C) 2019 Elsevier Ltd. All rights reserved.
Organik Rankine çevrimi entegre edilmiş S-CO2 kullanılan bir gaz türbin çevriminin termodinamik ve termoekonomik analizi
(2018) Tozlu, Alperen; Özahi, Emrah; Abuşoğlu, Ayşegül
Bu çalışmada, Organik Rankine Çevrimi (ORÇ) entegre edilmiş süperkritik CO2'nin (S-CO2) aracı akışkanolarak kullanıldığı bir gaz türbin çevrimi modeli gerçekleştirilmiştir. Sistemin termodinamik analizleriASPEN Plus ve EES programları kullanılarak yapılmıştır. Termodinamik analizler sonucunda, önerilensistemin elektrik üretim kapasitesi, enerji ve ekserji verimleri sırasıyla 1530,88 kW, % 23,30 ve % 59,60olarak bulunmuştur. Sistemin termoekonomik analizi için ikinci kanuna bağlı maliyet hesabı yöntemleriarasında yaygın olarak kullanılan özgül ekserji maliyetlendirme (SPECO) yöntemi kullanılmıştır. Önerilensistemde üretilecek elektriğin birim maliyeti 1 kW-saat için 7,28 ve toplam 1530,88 kW-saat elektriküretim bedeli için ise 111,43 olarak hesaplanmıştır. ORÇ entegre edilmiş S-CO2 kullanılan gaz türbinçevrim sisteminin toplam yatırım maliyeti ve üretilecek elektriğin maliyeti ile satış bedeli arasındaki farkdikkate alınarak sistemden elde edilecek yıllık kar 741.146 olarak hesaplanmıştır. Yapılan termoekonomikanaliz neticesinde sistemin amortisman süresi 4,09 yıl olarak bulunmuştur.
Techno-economic assessment of a synthetic fuel production facility by hydrogenation of CO2 captured from biogas
(Pergamon-Elsevier Science Ltd, 2022) 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 electrolyzes 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. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Thermodynamic feasibility analysis of a newly modified absorption power cycle running with LiBr-water
(Wiley, 2021) Tozlu, Alperen; Yosaf, Salem A.; ozcan, Hasan
This study thermodynamically evaluates a newly modified absorption power cycle (APC) working with Lithium Bromide-Water (LiBr-H2O) solution and compares it with the conventional Rankine, one-stage, and three-stage APC systems. An additional steam condenser is integrated to the conventional APC and part of pure water is extracted and pumped back to the high-pressure side without passing through the absorber of the cycle. In order to specify the best system parameters, parametric optimization of all configurations is evaluated. The Rankine cycle and the modified APC have better thermodynamic performances than those of the conventional and the three-stage APC at generator temperatures. The conventional APC is found to improve the cycle performance at low generator pressure. However, the efficiencies of this cycle start to decrease when generator pressure increases. In contrast, the Rankine cycle and the modified APC have larger working ranges of generator pressure.
Thermoeconomic analysis of a hybrid cogeneration plant with use of near-surface geothermal sources in Turkey
(Pergamon-Elsevier Science Ltd, 2021) Tozlu, Alperen; Gencaslan, Betul; Ozcan, Hasan
In this study, thermodynamic and thermoeconomic analyses of systems that produce electricity and heat through the use and storage of solar energy and near-surface geothermal sources are carried out. Three different configurations, which are the organic Rankine cycle (ORC), cogeneration system (CGN) and hybrid system (HYB), are coupled to the parabolic trough collector (PTC) system. The systems are named PTC-ORC, PTC-CGN and PTC-HYB are conducted. The reference system called PTC-ORC only produces electrical energy with parabolic trough collectors and it does not have a thermal energy storage system, whereas in PTC-CGN, in addition to the cogeneration of electricity and heat, thermal energy storage is also available. Finally, thermodynamic and economic analyses are conducted in the PTC-HYB with the assistance of near-surface geothermal energy, which is widely available in Turkey. In this study, the actual data of Ankara Kizilcahamam near-surface geothermal fields are taken as the heat source for the hybrid system. These facilities, each producing 1 MW of electricity, are first optimized with the help of parametric studies, and exergoeconomic analysis is performed with respect to optimum thermal conditions. The electricity production costs of PTC-ORC, PTC-CGN and PTC-HYB are found to be 0.257 $/kWh, 0.448 $/kWh and 0.401 $/kWh, respectively. The study demonstrates that thermal energy storage brings extra costs, while near-surface geothermal sources may help decrease energy costs from renewables. (c) 2021 Elsevier Ltd. All rights reserved.
Thermoeconomic analysis of a low-temperature waste-energy assisted power and hydrogen plant at off-NG grid region
(Elsevier, 2022) Tozlu, Alperen; Kayabasi, Erhan; Ozcan, Hasan
In this study, thermoeconomic analysis of a CO2 power cycle and PEM hydrogen system using ultra-low temperature waste heat from a milk production facility is conducted. In the transcritical CO2 cycle, low-temperature LNG evaporation is used for cooling the condenser to increase the temperature difference enabling low temperature waste heat use. In addition, a PEM electrolyzer produces hydrogen to reduce the LNG requirement at the plant. A CO2-water exchanger has been designed to recover the pasteurized water's excess heat and evaporate the CO2 using Simcenter-Flomaster software. The inlet mass flow rates and outlet temperatures of the heat exchanger were optimized by performing thermoecomic analysis, and the thermal and economic performance of the facility was examined. The power cycle has 14% higher efficiency when LNG is used as the heat sink compared to ambient temperature condensation with an electricity production cost range at 0.05-0.11 $/kWh, and the hydrogen generation cost is between $2.6-5.20 kg(-1). It is found that the plant could only be economically feasible when less than 50% of the power produced is used for hydrogen generation. Consequently, the proposed system can co-generate power and on-demand hydrogen in off-NG grid regions with reasonable investment and product costs.
An Updated Portrait of Numerical Analyses on Spout-Fluidized Bed Incineration Systems
(Springer International Publishing Ag, 2020) Ozahi, Emrah; Cutay, Arif; Abusoglu, Aysegul; Tozlu, Alperen
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.

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