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1
Shamoushaki, Moein, Mehdi Aliehyaei, and Farhad Taghizadeh-Hesary. "Energy, Exergy, Exergoeconomic, and Exergoenvironmental Assessment of Flash-Binary Geothermal Combined Cooling, Heating and Power Cycle." Energies 14, no. 15 (2021): 4464. http://dx.doi.org/10.3390/en14154464.
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This research presents the energy, exergy, economic, and environmental assessment, and multi-objective optimization of a flash-binary geothermal CCHP cycle. A sensitivity analysis of production well inlet temperature and cooling to power flow ratio on exergetic, economic, and environmental parameters was conducted. Furthermore, the effects of the inflation rate and plant working hours on economic parameters were investigated. Results showed that increasing the production well inlet temperature harms exergy efficiency and exergetic performance criteria and results in a gain in exergo-environmental impact index and heating capacity. In addition, the total plant cost increased by raising the production well temperature. Furthermore, increasing the cooling to power flow ratio caused a reduction in exergy efficiency, exergetic performance criteria, and produced net power and an enhancement in exergy destruction, cooling capacity, and total plant cost. The exergy efficiency and total cost rate in the base case were 58% and 0.1764, respectively. Optimization results showed that at the selected optimum point, exergy efficiency was 4.5% higher, and the total cost rate was 10.3% lower than the base case. Levelized cost of energy and the pay-back period at the optimum point was obtained as 6.22 c$/kWh, 3.43 years, which were 5.14% and 6.7% lower than the base case.
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Taslimi Taleghani, Sahar, Mikhail Sorin, and Sébastien Poncet. "Analysis and Optimization of Exergy Flows inside a Transcritical CO2 Ejector for Refrigeration, Air Conditioning and Heat Pump Cycles." Energies 12, no. 9 (2019): 1686. http://dx.doi.org/10.3390/en12091686.
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In this study, the exergy analysis of a CO2 (R744) two-phase ejector was performed using a 1D model for both single and double choking conditions. The impact of the back pressure on the exergy destruction and exergy efficiencies was presented to evaluate the exergy performance under different working conditions. The results of two exergy performance criteria (transiting exergy efficiency and Grassmann exergy efficiency) were compared for three modes of an ejector functioning: Double choking, single choking and at the critical point. The behavior of three thermodynamic metrics: Exergy produced, exergy consumed and exergy destruction were evaluated. An important result concerning the ejector’s design was the presence of a maximum value of transiting exergy efficiency around the critical point. The impact of the gas cooler and evaporator pressure variations on the different types of exergy, the irreversibilities and the ejector global performance were investigated for a transcritical CO2 ejector system. It was also shown that the transiting exergy flow had an important effect on the exergy analysis of the system and the Grassmann exergy efficiency was not an appropriate criterion to evaluate a transcritical CO2 ejector performance.
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Sejkora, Christoph, Lisa Kühberger, Fabian Radner, Alexander Trattner, and Thomas Kienberger. "Exergy as Criteria for Efficient Energy Systems—A Spatially Resolved Comparison of the Current Exergy Consumption, the Current Useful Exergy Demand and Renewable Exergy Potential." Energies 13, no. 4 (2020): 843. http://dx.doi.org/10.3390/en13040843.
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The energy transition from fossil-based energy sources to renewable energy sources of an industrialized country is a big challenge and needs major systemic changes to the energy supply. Such changes require a holistic view of the energy system, which includes both renewable potentials and consumption. Thereby exergy, which describes the quality of energy, must also be considered. In this work, the determination and analysis of such a holistic view of a country are presented, using Austria as an example. The methodology enables the calculation of the spatially resolved current exergy consumption, the spatially resolved current useful exergy demand and the spatially resolved technical potential of renewable energy sources (RES). Top-down and bottom-up approaches are combined in order to increase accuracy. We found that, currently, Austria cannot self-supply with exergy using only RES. Therefore, Austria should increase the efficiency of its energy system, since the overall exergy efficiency is only at 34%. The spatially resolved analysis shows that in Austria the exergy potential of RES is rather evenly distributed. In contrast, the exergy consumption is concentrated in urban and industrial areas. Therefore, the future energy infrastructure must compensate for these spatial discrepancies.
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Le Minh Nhut, Ha Nguyen Minh, and Luan Nguyen Thanh. "The Effective and Exergy Efficiency of Multi-Pass Solar Air Collector with Longitudinal Fins: Analysis and Optimization." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 102, no. 2 (2023): 42–65. http://dx.doi.org/10.37934/arfmts.102.2.4265.
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The present work investigates the exergy and effective efficiency of the multi-pass solar air collector with longitudinal fins by analysis approach and multi-objective optimization. The effect of 0.01-0.02 kg/s air flow rate, 15-35 mm collector depth, 1-3 m collector length, and 24.21-30.67 mm fin pitch was considered. The optimization was analyzed by the Preference Selection Index (PSI) method, with three maximum criteria: thermal efficiency, effective efficiency, and exergy efficiency. Mathematical models were solved by EES software. Results indicated that the multi-pass (TPLF and DPLF) type was better than the SPWF type by three criteria. The highest exergy efficiency of the TPLF and DPLF types was 6.696% and 5.636%. The greatest effective efficiency of the TPLF and DPLF types was 69.09% and 66.17%. Furthermore, the optimization results indicated that the three efficiency criteria of the DPLF type were 58.38%, 58.22%, and 4.491% for the best case; the three efficiency criteria of the TPLF type were 60.97%, 60.85%, and 5.439% for the best case. The worst configuration was the model with a short collector length, large collector depth, and large fin pitch. The collector efficiency decreased with decreased fin pitch for the configuration with the large collector length, short collector depth, and high mass flow rate.
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Nataliia, Fialko, Stepanova Alla, Navrodska Raisa, and Shevchuk Svitlana. "Comparative analysis of the exergy efficiency of methods for protecting gas exhaust ducts of boiler plants." Eastern-European Journal of Enterprise Technologies 3, no. 8 (111) (2021): 42–49. https://doi.org/10.15587/1729-4061.2021.234026.
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This paper reports the results of studying the exergy effectiveness of thermal methods for anti-corrosion protection of the gas-draining tracts of boiler plants. These include the method of mixing heated air into flue gases, the method of passing part of the hot gases of the boiler through the bypass chimney, and a flue gas drying method. The research involved the devised comprehensive procedure based on an exergy approach. The dependences of exergy loss E<sub>los</sub> and the heat- exergy criterion ε on the following parameters of thermal methods have been established: the amount of heated air N mixed into flue gases, the proportion of bypassed flue gases K, and the amount of dried flue gases R. A comparative analysis of the effectiveness of heat recovery systems when applying the methods considered has been performed. It has been established that for the method of mixing, E<sub>los</sub> and ε at ambient temperature t<sub>en</sub>=10 °C demonstrate the lowest values, that is, the efficiency of the system, in this case, is the highest. The most effective, when implementing the bypass method, is the heat recovery system at t<sub>en</sub>=10 °C. Under the method of drying, at all values of the amount of dried flue gases, the loss of exergy is the lowest at t<sub>en</sub>=0 °C. As regards the heat- exergy criterion, at values R≤20 %, the lowest values of ε are observed at t<sub>en</sub>=10 °C. At R>20 %, the lowest values of ε are at t<sub>en</sub>=0 °C. Thus, the efficiency of the system when implementing the method of drying is the highest at t<sub>en</sub>=0 °C and at the amount of dried air of R>20 %. The study reported here would provide the necessary information for designing optimal heat recovery schemes. The development of this study is to establish the relationship between the exergy and environmental efficiency of thermal protection methods in order to further reduce toxic emissions.
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Bou Malham, Zoughaib, Tinoco, and Schuhler. "Hybrid Optimization Methodology (Exergy/Pinch) and Application on a Simple Process." Energies 12, no. 17 (2019): 3324. http://dx.doi.org/10.3390/en12173324.
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In the light of the alarming impending energy scene, energy efficiency and exergy efficiency are unmistakably gathering momentum. Among efficient process design methodologies, literature suggests pinch analysis and exergy analysis as two powerful thermodynamic methods, each showing certain drawbacks, however. In this perspective, this article puts forward a methodology that couples pinch and exergy analysis in a way to surpass their individual limitations in the aim of generating optimal operating conditions and topology for industrial processes. Using new optimizing exergy‐based criteria, exergy analysis is used not only to assess the exergy but also to guide the potential improvements in industrial processes structure and operating conditions. And while pinch analysis considers only heat integration to satisfy existent needs, the proposed methodology allows including other forms of recoverable exergy and explores new synergy pathways through conversion systems. A simple case study is proposed to demonstrate the applicability and efficiency of the proposed method.
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Haroon, Muhammad, Nadeem Ahmed Sheikh, Abubakr Ayub, et al. "Exergetic, Economic and Exergo-Environmental Analysis of Bottoming Power Cycles Operating with CO2-Based Binary Mixture." Energies 13, no. 19 (2020): 5080. http://dx.doi.org/10.3390/en13195080.
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This study focused on investigating the bottoming power cycles operating with CO2-based binary mixture, taking into account exergetic, economic and exergo-environmental impact indices. The main intent is to assess the benefits of employing a CO2-based mixture working fluid in closed Brayton bottoming power cycles in comparison with pure CO2 working fluid. Firstly, selection criteria for the choice of suitable additive compound for CO2-based binary mixture is delineated and the composition of the binary mixture is decided based on required cycle minimum temperature. The decided CO2-C7H8 binary mixture with a 0.9 mole fraction of CO2 is analyzed in two cycle configurations: Simple regenerative cycle (SRC) and Partial heating cycle (PHC). Comparative analysis among two configurations with selected working fluid are carried out. Thermodynamic analyses at varying cycle pressure ratio shows that cycle with CO2-C7H8 mixture shows maximum power output and exergy efficiency at rather higher cycle pressure ratio compared to pure CO2 power cycles. PHC with CO2-C7H8 mixture shows 28.68% increment in exergy efficiency with the levelized cost of electricity (LCOE) 21.62% higher than pure CO2 PHC. Whereas, SRC with CO2-C7H8 mixture shows 25.17% increment in exergy efficiency with LCOE 57.14% higher than pure CO2 SRC. Besides showing lower economic value, cycles with a CO2-C7H8 mixture saves larger CO2 emissions and also shows greater exergo-environmental impact improvement and plant sustainability index.
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Fialko, N., A. Stepanova, R. Navrodskaya, S. Shevchuk, and G. Sbrodova. "Optimization of operating parameters a heat-recovery exchanger of a boiler plant based on the exergy approach." Energy and automation, no. 2(54) (June 22, 2021): 5–16. http://dx.doi.org/10.31548/energiya2021.02.005.
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Abstract. The results of operating parameters optimization of the air-heating heat-recovery exchanger of complex heat recovery system of a gas-fired boiler designed for heating water and blown air are presented. Air heating in this heat-recovery exchanger is realized by deep cooling of the waste exhaust gases, that is, with a change in their moisture content during the heat recovery process. The possibilities of using a complex technique based on the structural-variant method and exergy analysis methods for the optimization of the heat-recovery exchanger are analyzed. The developed structural scheme of the boiler plant with identification of input and output exergy streams for all elements of the installation is presented. The change of exergy losses in this heat-recovery exchanger has a rather strong effect on the change of the whole heat recovery system efficiency is established. Thus, the optimization of heat-recovery exchanger operating parameters of is a necessary condition for increasing the efficiency of heat recovery in general. The choice of multiplicative exergy efficiency criteria used as target functions of operating parameters optimization of the investigated air-heating heat exchanger is substantiated. The obtained dependences of exergy efficiency criteria on the operating parameters of the heat-recovery exchanger, such as the ratio of the Reynolds numbers of exhaust gases and air and the ratio of the initial and final moisture content of exhaust gases, are analyzed. It is established that the minimum values of the efficiency criteria, which corresponds to the maximum exergy efficiency, is observed in the range of values of the ratio of the initial and final moisture content of exhaust gases in the range from 2.4 to 3.0. It is shown that at a value of the specified ratio of 2.7, the exergy efficiency of the investigated heat-recovery exchanger does not depend on the ratio of the Reynolds numbers of exhaust gases and air. It is established that of initial and final moisture content ratio of exhaust gases, equal to 2.7, and the Reynolds numbers ratio of exhaust gases and air, equal to 0.8 and 1.2, depending on the values of initial and final moisture content ratio of exhaust gases, can be taken as the optimal values of the operating parameters. Key words: heat-recovery exchangers, exergy efficiency, complex techniques
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Adeniran, Jamiu Adetayo, Rafiu Olasunkanmi Yusuf, Adeniyi Saheed Aremu, and Temitope Mariam Aareola. "Exergetic analysis and pollutants emission from a rotary kiln system in a major cement manufacturing plant." Energy & Environment 30, no. 4 (2018): 601–16. http://dx.doi.org/10.1177/0958305x18802766.
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The exergy analysis and air pollutants emission estimation from the kiln system of a major cement manufacturing plant located in Nigeria were conducted with a view to improve the level of performance of the production unit and minimize environmental effects. Material balance and exergy analysis were carried out on the system to determine the exergetic efficiency and exergy destruction rate. Pollutants emission was estimated using bottom-up emission factor approach. The physical and chemical exergy output obtained were 9.07×107 and 1.46×08 kJ/h, respectively. The exergy efficiency of the kiln system was 27.35%. The measure of entropy generation (6.53×108 kJ/h) represented a huge potential for energy savings for the unit. CO2 emission represented about 99.04% of the total criteria air pollutants emission from the kiln and an estimate of 0.90 tonnes of CO2/tonne of clinker produced was obtained. To improve the exergy efficiency and reduce pollutants emission from the kiln system, possible heat recovery options and CO2 mitigation approaches were suggested.
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Hasan, Moayed Razoki. "ENTROPY METHOD AS CRITERIA FOR ANALYSIS A STEAM POWER PLANT." Journal of Engineering 15, no. 03 (2009): 4025–40. http://dx.doi.org/10.31026/j.eng.2009.03.15.
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In this paper a theoretical analysis of South Baghdad and Dura power plant is carried out according to second law of thermodynamic depending on entropy (irreversibility coefficient or lost work) method instead of exergy (availability) method. In the used entropy method. The power plant is divided into main blocks ( boiler, turbine, condenser, and feed water heater and pumps ). The irreversibility losses and coefficient for each block are calculated and then the overall irreversibility and thermal efficiency of the plant are calculated. The results of this work are compared with previous results, that depending on exergy method. The comparison of results show that both methods give approximately the same results since both of them rely the 2nd law of thermodynamic. Entropy method is simple and intellectually and intuitively satisfying and giving direct relationship between components losses of power plant and its overall efficiency.
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Silva Ortiz, Maciel Filho, and Posada. "Mass and Heat Integration in Ethanol Production Mills for Enhanced Process Efficiency and Exergy-Based Renewability Performance." Processes 7, no. 10 (2019): 670. http://dx.doi.org/10.3390/pr7100670.
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This paper presents the process design and assessment of a sugarcane-based ethanol production system that combines the usage of both mass and heat integration (pinch analysis) strategies to enhance the process efficiency and renewability performance. Three configurations were analyzed: (i) Base case: traditional ethanol production (1G); (ii) mass-integrated (1G2G); and (iii) mass and heat-integrated system (1G2G-HI). The overall assessment of these systems was based on complementary approaches such as mass and mass–heat integration, energy and exergy analysis, exergy-based greenhouse gas (GHG) emissions, and renewability exergy criteria. The performances of the three cases were assessed through five key performance indicators (KIPs) divided into two groups: one is related to process performance, namely, energy efficiency, exergy efficiency, and average unitary exergy cost (AUEC), and the other one is associated to environmental performance i.e., exergy-based CO2-equation emissions and renewability exergy index. Results showed a higher exergy efficiency of 50% and the lowest AUEC of all the systems (1.61 kJ/kJ) for 1G2G-HI. Furthermore, the destroyed exergy in 1G2G-HI was lower by 7% and 9% in comparison to the 1G and 1G2G cases, respectively. Regarding the exergy-based GHG emissions and renewability performance (λindex), the 1G2G-HI case presented the lowest impacts in terms of the CO2-equivalent emissions (94.10 gCO2-eq/MJ products), while λindex was found to be environmentally unfavorable (λ = 0.77). However, λindex became favorable (λ > 1) when the useful exergy of the byproducts was considered.
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Ochoa, Guillermo Valencia, Carlos Acevedo Peñaloza, and Jhan Piero Rojas. "Thermoeconomic Modelling and Parametric Study of a Simple ORC for the Recovery of Waste Heat in a 2 MW Gas Engine under Different Working Fluids." Applied Sciences 9, no. 21 (2019): 4526. http://dx.doi.org/10.3390/app9214526.
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This paper presents a thermo-economic analysis of a simple organic Rankine cycle (SORC) as a waste heat recovery (WHR) systems of a 2 MW stationary gas engine evaluating different working fluids. Initially, a systematic methodology was implemented to select three organic fluids according to environmental and safety criteria, as well as critical system operational conditions. Then, thermodynamic, exergy, and exergo-economic models of the system were developed under certain defined considerations, and a set of parametric studies are presented considering key variables of the system such as pump efficiency, turbine efficiency, pinch point condenser, and evaporator. The results show the influence of these variables on the combined power of the system (gas engine plus ORC), ORC exergetic efficiency, specific fuel consumption (∆BSFC), and exergo indicators such as the payback period (PBP), levelized cost of energy (LCOE), and the specific investment cost (SIC). The results revealed that heat transfer equipment had the highest exergy destruction cost rates representing 81.25% of the total system cost. On the other hand, sensitivity analyses showed that acetone presented better energetic and exergetic performance when the efficiency of the turbine, evaporator, and condenser pinch point was increased. However, toluene was the fluid with the best results when pump efficiency was increased. In terms of the cost of exergy destroyed by equipment, the results revealed that acetone was the working fluid that positively impacted cost reduction when pump efficiency was improved; and toluene, when turbine efficiency was increased. Finally, the evaporator and condenser pinch point increased all the economic indicators of the system. In this sense, the working fluid with the best performance in economic terms was acetone, when the efficiency of the turbine, pinch condenser, and pinch evaporator was enhanced.
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Baghernejad, Ali, and Amjad Anvari-Moghaddam. "Exergoeconomic and Environmental Analysis and Multi-Objective Optimization of a New Regenerative Gas Turbine Combined Cycle." Applied Sciences 11, no. 23 (2021): 11554. http://dx.doi.org/10.3390/app112311554.
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Combined cycle systems have an important role in power generation. In the present study, three different configurations of combined Brayton and Rankine cycle system are studied from the perspective of energy, exergy, exergoeconomic and environmental perspectives. Results indicate that it depends on the preferences and criteria of each decision maker to select the best configuration among the three proposed configurations as the final configuration. For the purpose of parametric analysis, the effect of changing various parameters such as compressor pressure ratio, gas turbine inlet temperature on the output work, exergy efficiency, exergy-economic and environmental parameters is studied. In addition, an attempt is made to optimize the performance of combined cycle systems considering three objective functions of exergy efficiency, total cost rate and exergy unit cost of produced electricity.
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Hasan, Moayed Razoki. "ENTROPY METHOD AS CRITERIA FOR ANALYSIS OF A STEAM POWER PLANT." Journal of Engineering 12, no. 03 (2006): 1818–33. http://dx.doi.org/10.31026/j.eng.2006.03.15.
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In this paper a theoretical analysis of South Baghdad and Dura power plant is carried out according to second law of thermodynamic depending on entropy (irreversibility coefficient or lost work) method instead of exergy (availability) method. In the used entropy method. The power plant is divided into main blocks ( boiler, turbine, condenser, and feed water heater and pumps ). The irreversibility losses and coefficient for each block are calculated and then the overall irreversibility and thermal efficiency of the plant are calculated. The results of this work are compared with previous results, that depending on exergy method. The comparison of results show that both methods give approximately the same results since both of them rely the 2nd law of thermodynamic. Entropy method is simple and intellectually and intuitively satisfying and giving direct relationship between components losses of power plant and its overall efficiency.
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Ust, Y., A. Sinan Karakurt, and U. Gunes. "Performance Analysis of Multipurpose Refrigeration System (MRS) on Fishing Vessel." Polish Maritime Research 23, no. 2 (2016): 48–56. http://dx.doi.org/10.1515/pomr-2016-0020.
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Abstract The use of efficient refrigerator/freezers helps considerably to reduce the amount of the emitted greenhouse gas. A two-circuit refrigerator-freezer cycle (RF) reveals a higher energy saving potential than a conventional cycle with a single loop of serial evaporators, owing to pressure drop in each evaporator during refrigeration operation and low compression ratio. Therefore, several industrial applications and fish storage systems have been utilized by using multipurpose refrigeration cycle. That is why a theoretical performance analysis based on the exergetic performance coefficient, coefficient of performance (COP), exergy efficiency and exergy destruction ratio criteria, has been carried out for a multipurpose refrigeration system by using different refrigerants in serial and parallel operation conditions. The exergetic performance coefficient criterion is defined as the ratio of exergy output to the total exergy destruction rate (or loss rate of availability). According to the results of the study, the refrigerant R32 shows the best performance in terms of exergetic performance coefficient, COP, exergy efficiency, and exergy destruction ratio from among the other refrigerants (R1234yf, R1234ze, R404A, R407C, R410A, R143A and R502). The effects of the condenser, freezer-evaporator and refrigerator-evaporator temperatures on the exergetic performance coefficient, COP, exergy efficiency and exergy destruction ratios have been fully analyzed for the refrigerant R32.
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Donskoy, Igor. "Exergetic Efficiency of Coal Gasification Using High-Temperature Mixtures of O2/N2 and O2/CO2." International Journal of Thermodynamics, Erken Görünüm - Early Pub Issues (April 18, 2025): 1–8. https://doi.org/10.5541/ijot.1642883.
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A search for ways to improve the efficiency of energy technologies requires the selection of appropriate efficiency criteria and a study of the influence of different factors on them. This paper focuses on coal gasification, including hard coals and brown coals, in air and steam media, considering different efficiency criteria for gasification processes: cold gas efficiency, energy efficiency that takes into account the heat of the gasification agent, and exergy efficiency that considers the chemical, thermal, and mechanical energy of reactants and products. The dependence of these efficiency criteria on stoichiometric ratios and air temperature is demonstrated, and the applicability of these criteria in power plant analysis is discussed.
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Fialko, N., A. Stepanova, R. Navrodska, and S. Shevchuk. "Efficiency of different types gas heaters for chimney anticorrosion protection systems of boiler plants." Energy and automation, no. 1(53) (December 28, 2020): 5–16. http://dx.doi.org/10.31548/energiya2021.01.005.
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The of researches results of exergy efficiency and optimization of parameters of different types gas heaters by used for anticorrosion protection of gas exhaust ducts of heating boiler plants equipped with exhaust gas heat recovery systems are presented. The choice of a complex technique for analyzing the efficiency of gas heaters, which makes it possible to obtain functional dependences of the selected efficiency criteria on the geometric parameters of the heat exchange surface of gas heaters for solving optimization problems is substantiated. Such a technique can be a technique based on exergy methods and statistical methods of experiment planning theory. This technique by an insignificant number of initial parameters required for calculation, and by the simplicity of calculation and analytical methods for obtaining exergy characteristics is characterized. The work considered three types of gas heaters: water-heating (water-gas) and two gas-heating (gas-gas) pipe and plate type. The heat exchange surface of the water-heating gas heater is assembled from transverse-finned bimetallic (steel base and aluminum fins) pipes, gas-heating pipe-type - from steel pipes with circular turbulators flow, and gas-heating plate-type - from smooth steel plates. The general system of balance equations used in this complex technique, and also its the basic stages, are presented. It is noted that the choice of complex criteria for assessing the efficiency of gas heaters is carried out according to the degree of sensitivity of the criteria to changes in the operating and geometric parameters of gas heaters. Using the proposed sensitivity coefficient, the degree of sensitivity of different efficiency criteria has been analyzed and it has been established that one of the most sensitive to changes in the geometric parameters of the heat exchange surface of gas heaters is the heat-exergy criterion. The results of the corresponding calculations for each of the three gas heaters are presented. It has been established the most exergetically effective is a water-heating gas heater, followed by gas-heating gas heaters, of plate and tube types respectively.
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Pal, Jitendra Singh, Shivalingappa Nagappa Sapali, Anil Tumkur Ramakrishna, Niyaj Dilavar Shikalgar, and Ajit Shinde. "Exergy Criteria of Performance of Waste Heat Recovery Applied for Marine Auxiliary Boiler." International Journal of Heat and Technology 40, no. 1 (2022): 297–303. http://dx.doi.org/10.18280/ijht.400135.
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Auxiliary boilers onboard motor ships are the subject of ongoing research. Steam is produced by an auxiliary boiler for fuel heating and cargo oil pumping turbines. This marine boiler is a pressure jet burner water tube auxiliary boiler with a 70-80% efficiency rating. The goal of determining the process and components of irreversibility loss in a system is to identify the process and components of exergy losses. The second law of thermodynamics and the concept of irreversible entropy production are the foundations of this study's exergy technique of analysis. This concept of considering entropy at a given steady-state condition rather than as a change in a process is also one of the features of this exergy analysis of the marine oil-fired boiler. The exergy loss in the combustion chamber was calculated and determined to be 35024 kJ, which is the maximum irreversibility in this maritime auxiliary boiler. A numerical analysis of the current nozzle jet burner is undertaken to evaluate the enhancement of the combustion process. The temperature and velocity contour of the fuel stream passing through the nozzle of this auxiliary boiler's burner depicts atomization.
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Liu, Ji, Jie Ren, Yujia Zhang, Weilong Huang, Chen Xu, and Lu Liu. "Exergoeconomic Evaluation of a Cogeneration System Driven by a Natural Gas and Biomass Co-Firing Gas Turbine Combined with a Steam Rankine Cycle, Organic Rankine Cycle, and Absorption Chiller." Processes 12, no. 1 (2023): 82. http://dx.doi.org/10.3390/pr12010082.
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Considering energy conversion efficiency, pollution emissions, and economic benefits, combining biomass with fossil fuels in power generation facilities is a viable approach to address prevailing energy deficits and environmental challenges. This research aimed to investigate the thermodynamic and exergoeconomic performance of a novel power and cooling cogeneration system based on a natural gas–biomass dual fuel gas turbine (DFGT). In this system, a steam Rankine cycle (SRC), a single-effect absorption chiller (SEAC), and an organic Rankine cycle (ORC) are employed as bottoming cycles for the waste heat cascade utilization of the DFGT. The effects of main operating parameters on the performance criteria are examined, and multi-objective optimization is accomplished with a genetic algorithm using exergy efficiency and the sum unit cost of the product (SUCP) as the objective functions. The results demonstrate the higher energy utilization efficiency of the proposed system with the thermal and exergy efficiencies of 75.69% and 41.76%, respectively, while the SUCP is 13.37 $/GJ. The exergy analysis reveals that the combustion chamber takes the largest proportion of the exergy destruction rate. The parametric analysis shows that the thermal and exergy efficiencies, as well as the SUCP, rise with the increase in the gas turbine inlet temperature or with the decrease in the preheated air temperature. Higher exergy efficiency and lower SUCP could be obtained by increasing the SRC turbine inlet pressure or decreasing the SRC condensation temperature. Finally, optimization results indicate that the system with an optimum solution yields 0.3% higher exergy efficiency and 2.8% lower SUCP compared with the base case.
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Syah, Rahmad, Afshin Davarpanah, Mahyuddin K. M. Nasution, Faisal Amri Tanjung, Meysam Majidi Nezhad, and Mehdi Nesaht. "A Comprehensive Thermoeconomic Evaluation and Multi-Criteria Optimization of a Combined MCFC/TEG System." Sustainability 13, no. 23 (2021): 13187. http://dx.doi.org/10.3390/su132313187.
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In this study, an integrated molten carbonate fuel cell (MCFC), thermoelectric generator (TEG), and regenerator energy system has been introduced and evaluated. MCFC generates power and heating load. The exit fuel gases of the MCFC is separated into three sections: the first section is transferred to the TEG to generate more electricity, the next chunk is conducted to a regenerator to boost the productivity of the suggested plant and compensate for the regenerative destructions, and the last section enters the surrounding. Computational simulation and thermodynamic evaluation of the hybrid plant are carried out utilizing MATLAB and HYSYS software, respectively. Furthermore, a thermoeconomic analysis is performed to estimate the total cost of the product and the system cost rate. The offered system is also optimized using multi-criteria genetic algorithm optimization to enhance the exergetic efficiency while reducing the total cost of the product. The power generated by MCFC and TEG is 1247.3 W and 8.37 W, respectively. The result explicates that the provided electricity and provided efficiency of the suggested plant is 1255.67 W and 38%, respectively. Exergy inquiry outcomes betokened that, exergy destruction of the MCFC and TEG is 13,945.9 kW and 262.75 kW, respectively. Furthermore, their exergy efficiency is 68.22% and 97.31%, respectively. The impacts of other parameters like working temperature and pressure, thermal conductance, the configuration of the advantage of the materials, etc., on the thermal and exergetic performance of the suggested system are also evaluated. The optimization outcomes reveal that in the final optimum solution point, the exergetic efficiency and total cost of the product s determined at 70% and 30 USD/GJ.
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Rouboa, Abel, Valter Silva, and Nuno Couto. "Exergy Analysis in Hydrogen-Air Detonation." Journal of Applied Mathematics 2012 (2012): 1–16. http://dx.doi.org/10.1155/2012/502979.
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The main goal of this paper is to analyze the exergy losses during the shock and rarefaction wave of hydrogen-air mixture. First, detonation parameters (pressure, temperature, density, and species mass fraction) are calculated for three cases where the hydrogen mass fraction in air is 1.5%, 2.5%, and 5%. Then, exergy efficiency is used as objective criteria of performance evaluation. A two-dimensional computational fluid dynamic code is developed using Finite volume discretization method coupled with implicit scheme for the time discretization (Euler system equations). A seven-species and five-step global reactions mechanism is used. Implicit total variation diminishing (TVD) algorithm, based on Riemann solver, is solved. The typical diagrams of exergy balances of hydrogen detonation in air are calculated for each case. The energy balance shows a successive conversion of kinetic energy, and total enthalpy, however, does not indicate consequent losses. On the other hand, exergy losses increase with the augment of hydrogen concentration in air. It obtained an exergetic efficiency of 77.2%, 73.4% and 69.7% for the hydrogen concentrations of 1.5%, 2.5%, and 5%, respectively.
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Konstantin, Kostov. "DETERMINATION OF TECHNICAL AND ECONOMIC INDICATORS OF THERMAL POWER STATIONS DIRECTLY FROM THE TURBINE REGIME CHARACTERISTICS." EUREKA: Physics and Engineering 4 (July 31, 2020): 51–59. https://doi.org/10.21303/2461-4262.2020.001358.
Full textAbstract:
The distribution of costs for electricity and heat production is accomplished by a number of fairly conditional methods. Cost analysis and allocation must be carried out on the basis of objective technical and economic criteria. The application of a method is determined by the introduced regulatory frameworks, energy markets and the prices of energy products. There are two fundamental methods – "physical" and "exergy". The physical method is based on the distribution of costs, and the exergy on the second law of thermodynamics. The article reviews and analyzes the tariff policy of the Thermal power plant. Objective criteria have been identified to serve as a means of forecasting and controlling fuel consumption. The thermal efficiency of a Thermal power plant has been evaluated. A comparison was made with similar Thermal power plants. A fundamentally new approach is proposed to determine the main technical and economic criteria of the plant. The proposed method allows determining indicators that uniquely characterize the thermal and economic efficiency of the plant without the need for diversification of fuel costs
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Hassan, Alamir H., Zhirong Liao, Kaichen Wang, Mostafa M. Abdelsamie, Chao Xu, and Yanhui Wang. "Exergy and Exergoeconomic Analysis for the Proton Exchange Membrane Water Electrolysis under Various Operating Conditions and Design Parameters." Energies 15, no. 21 (2022): 8247. http://dx.doi.org/10.3390/en15218247.
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Integrating the exergy and economic analyses of water electrolyzers is the pivotal way to comprehend the interplay of system costs and improve system performance. For this, a 3D numerical model based on COMSOL Multiphysics Software (version 5.6, COMSOL, Stockholm, Sweden) is integrated with the exergy and exergoeconomic analysis to evaluate the exergoeconomic performance of the proton exchange membrane water electrolysis (PEMWE) under different operating conditions (operating temperature, cathode pressure, current density) and design parameter (membrane thickness). Further, the gas crossover phenomenon is investigated to estimate the impact of gas leakage on analysis reliability under various conditions and criteria. The results reveal that increasing the operating temperature or decreasing the membrane thickness improves both the efficiency and cost of hydrogen exergy while increasing the gas leakage through the membrane. Likewise, raising the current density and the cathode pressure lowers the hydrogen exergy cost and improves the economic performance. The increase in exergy destroyed and hydrogen exergy cost, as well as the decline in second law efficiency due to the gas crossover, are more noticeable at higher pressures. As the cathode pressure rises from 1 to 30 bar at a current density of 10,000 A/m2, the increase in exergy destroyed and hydrogen exergy cost, as well as the decline in second law efficiency, are increased by 37.6 kJ/mol, 4.49 USD/GJ, and 7.1%, respectively. The cheapest green electricity source, which is achieved using onshore wind energy and hydropower, reduces hydrogen production costs and enhances economic efficiency. The growth in the hydrogen exergy cost is by about 4.23 USD/GJ for a 0.01 USD/kWh increase in electricity price at the current density of 20,000 A/m2. All findings would be expected to be quite useful for researchers engaged in the design, development, and optimization of PEMWE.
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Minh Phu, Nguyen, and Nguyen Thanh Luan. "A Review of Energy and Exergy Analyses of a Roughened Solar Air Heater." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 77, no. 2 (2020): 160–75. http://dx.doi.org/10.37934/arfmts.77.2.160175.
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In this paper, eleven roughness elements in solar air heater duct analysed both energy and exergy were reviewed. Various roughness geometries such as ribs, twisted tap, baffles, and metal waste were surveyed about heat transfer and friction when the air flow is passing absorber plate. Evaluation criteria of roughness on the absorber plate including thermohydraulic performance parameter, thermal efficiency, effective efficiency, and exergy efficiency were presented and compared. Results showed that protruded ribs in arc shape indicated the largest Nusselt number. The ribs exhibited the highest thermohydraulic performance parameter at a Reynolds number greater than 5000. Jet impingement with arc-shaped ribs and roughness elements of metal waste were found the smallest exergy efficiencies. The biggest effective and exergy efficiencies were obtained to be 70% and 1.9%, respectively. The thermohydraulic performance parameter varied from 0.5 to 2.0. The review paper aims to provide information about roughness geometries investigated both first and second laws of thermodynamics and figure of merits to overview artificial roughness in a solar air heater.
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Fialko, N., A. Stepanova, R. Navrodska, and S. Shevchuk. "Optimization of geometric parameters and analysis of exergy efficiency of heat recovery units glass furnaces." Energy and automation, no. 3(55) (June 23, 2021): 5–17. http://dx.doi.org/10.31548/energiya2021.03.005.
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The paper presents the results of optimization of the geometric parameters of the heat exchange surface of water and air-heating heat exchangers of glass-making furnaces and an analysis of their exergy efficiency. Ensuring the efficient operation of heat recovery units in various thermal circuits is an urgent problem of heat power engineering. The aim of the work is to establish the optimal areas of the geometric parameters of the heat exchange surface of heat recovery units of glass-melting furnaces and to analyze their exergy efficiency. The paper presents the results of solving the tasks necessary to achieve the goal: - using statistical methods for planning the experiment, determine the levels of variation of the parameters of the geometric surface of heat transfer for the heat recovery units under study and calculate the values of the criteria for evaluating the efficiency at the points of the central orthogonal compositional plan; - to obtain the regression equations for the investigated heat exchangers, to determine the optimal areas of change in the geometric parameters of the heat exchange surface and the corresponding exergy efficiency criteria. To determine the optimal areas of geometric parameters of the heat exchange surface, a complex methodology is used based on the methods of exergy analysis and statistical methods of the theory of experiment planning. It has been established that when designing heat recovery schemes for heating water in heat supply systems and for heating blast air, heat recovery units with the following values of the areas of variation of the geometric parameters of the heat exchange surface can be used: - the values of the area of variation of the distance between the panels for heat recovery units with a staggered and corridor arrangement of pipes in a bundle s1 = 58.0-62.0 mm. - the values of the areas of change in the diameter of pipes for a hot water heat exchanger with a corridor arrangement of pipes d = 41.0-43.0 mm and for an air heating heat exchanger with a staggered and corridor arrangement of pipes d = 29.0-31.0 mm. - the use of the values of the ranges of change of other parameters is carried out taking into account additional technological factors. It has been established that the exergy efficiency of hot water heat recovery units is in all cases higher than the exergy efficiency of air heating units. For hot water heat exchangers, the values of exergy criteria are lower than for air heating ones: k – 2.0 times, ε – by 7.5%, m0 – 1.9 times. The expediency of using the investigated heat recovery units in heat recovery circuits of glass melting furnaces has been established, taking into account the results obtained and in the presence of certain technological factors. The results obtained and further developments in the field of optimization of the operating parameters of heat recovery units for glass-melting furnaces will provide an increase in the efficiency of heat recovery equipment for power plants.
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Abam, Fidelis I., Bassey B. Okon, Isuamfon F. Edem, Macmanus C. Ndukwu, Ene B. Ekpo, and Ogheneruona E. Diemuodeke. "Environmental assessment and CO2emissions of Brayton cycle configurations based on exergo-sustainability, economic and ecological efficiency using multi-criteria optimization technique." Future Technology 3, no. 1 (2024): 1–12. http://dx.doi.org/10.55670/fpll.futech.3.1.1.
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The performance indicators of Brayton cycle configurations (BCY) for the topping cycle application are presented. The indicators include exergy efficiency, ecological efficiency, sustainability index, environmental impact, and economic parameters. The study's objective is to access the key indicators of sustainability and investment cost to provide valid information for the choice of GT configuration as topping cycles. Five BCY configurations (Model 1 to Model 5) were studied. The maximum exergy efficiency of 28 % was obtained across the studied models. In addition, the waste exergy ratios, environmental effect factors, and CO2 emissions were determined for each model. The CO2 emissions were found to vary from 102.8 to 168 kg/MWh. Model 1 and Model 5 had the highest payback periods of 2.3 and 3.6 years, respectively, with the least unit cost of energy. Similarly, the highest cost of investment was obtained with Model 5. Results from the TOPPIS analysis show that the closeness to the final positive ideal solution varied from 0.218 to 0. 56 across the BCYs. The best model close to ideality was model 5 and thus ranked first and based principally on economic, technical, and environmental sustainability. Furthermore, the optimization results show that there are prospects for system retrofitting.
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Fialko, M., A. Stepanova, S. Shevchuk, and G. Sbrodova. "COMPREHENSIVE METHODS OF EVALUATION OF EFFICIENCY AND OPTIMIZATION OF HEAT-UTILIZATION SYSTEMS." Industrial Heat Engineering 40, no. 4 (2018): 25–33. http://dx.doi.org/10.31472/ihe.4.2018.04.
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At present, Ukraine has the necessary potential for the implementation of effective energy-saving technologies for heat recovery, and therefore the problem of their development and implementation is relevant for the country's energy sector. The solution of this problem is related to the need for systematic studies of the efficiency of optimization of heat recovery facilities from the standpoint of modern methodological approaches. The paper outlines the main stages in the development of integrated methods for assessing the efficiency and optimization of heat recovery systems based on the principles of exergic analysis, statistical methods for planning the experiment, structured variational methods, multilevel optimization methods, the theory of linear systems and the thermodynamics of irreversible processes. Examples and illustrations illustrate some of the stages in the development of complex methods. The necessary general step in the development of methodologies is the development of new performance criteria. Such criteria are highly sensitive to changes in the regime and design parameters of heat recovery systems due to the inclusion of some exergic characteristics in them. The developed criteria also serve as target optimization functions. For individual elements of heat recovery systems, efficiency and optimization methods usually include the definition of the functional dependencies of the selected efficiency criteria on the main parameters. For this, balance methods of exergic analysis and statistical methods of experiment planning are used. If such dependencies are established, optimization is carried out using known mathematical methods. For complex heat recovery systems involving a large number of elements, it is not possible to establish general analytical dependencies of the optimization objective functions on the parameters of the system when constructing mathematical models necessary for their optimization. Complex methods based on the basic principles of structural-variant methods, methods of multilevel optimization, the theory of linear systems, and the thermodynamics of irreversible processes have been developed for such cases. For this purpose, structural diagrams of plants, block diagrams of multi-level optimization have been developed, complete input matrices have been constructed, mathematical models for the processes under investigation have been developed, formulas have been derived for calculating the loss of exergy power in heat conduction processes and formulas for calculating dissipators of exergy. A well-founded choice of the methodology for evaluating efficiency and optimization raises the effectiveness of optimization, since it allows the use of parameters maximally close to optimal when developing the heat recovery system design, which in turn increases the efficiency of the system. References 14, figures 5.
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Karaali, Rabi, and Arzu Keven. "Evaluation of four different cogeneration cycles by using some criteria." Applied Rheology 32, no. 1 (2022): 122–37. http://dx.doi.org/10.1515/arh-2022-0128.
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Abstract The purpose of this article is to evaluate four different gas turbine cogeneration cycles which are basic, absorption cooling, air heating and air fuel heating cogeneration cycles by using the most important six evaluation criteria for different excess air coefficient, different compression rates, and different compressor inlet air temperatures. These six evaluation criteria are electrical heat ratio, exergy efficiency, incremental heat rate, artificial thermal efficiency, fuel energy saving ratio, and specific fuel consumption. It is seen that the air-fuel heating cogeneration cycle is the most efficient among the cycles examined for a certain compressor compression ratio, followed by the air heating, basic, and absorption cooling cycles.
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Montes, María José, Rubén Abbas, Rubén Barbero, and Antonio Rovira. "A new design of multi-tube receiver for Fresnel technology to increase the thermal performance." Applied Thermal Engineering 204 (December 20, 2021): 117970. https://doi.org/10.1016/j.applthermaleng.2021.117970.
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This work is focused on the multi-tube receiver for this Fresnel collector, proposing a thermal design based on three criteria that can be generalized for any multi-tube receiver: the fluid flow layout is arranged to meet the symmetry of the solar flux map; the fluid circulates from the lower to the higher flux density zone; and the fluid velocity is modified by modifying the tube diameter, to optimize the heat transfer. Following these criteria, the final configuration of the receiver is chosen based on an exergy optimization, in which both heat loss and pressure drop must be quantified. It has been also accomplished a generalization of the optimization methodology for Fresnel collectors providing heat at different temperatures, showing that, in these cases, the configuration that maximizes the exergy efficiency does not correspond to the one with the highest energy efficiency. This thermal design method can be applied to multi-tube receivers working at higher temperatures in longer Fresnel loops, in which case the optimization will result in more marked differences between the optimal values and the standard ones.
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Javadijam, Ramtin, Mohammad Hassan Shahverdian, Ali Sohani, and Hoseyn Sayyaadi. "A 4E Comparative Study between BIPV and BIPVT Systems in Order to Achieve Zero-Energy Building in Cold Climate." Buildings 13, no. 12 (2023): 3028. http://dx.doi.org/10.3390/buildings13123028.
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The growing demand for energy has led to the popularity of building integrated photovoltaic (BIPV) systems. However, photovoltaic (PV) system efficiency decreases as the temperature increases. To address this issue, a study was conducted on a BIPV thermal (BIPVT) system, which can generate both thermal and electrical energy, to enhance its efficiency. In this study, for the cold weather in Tabriz city in Iran, BIPV and BIPVT systems are compared with each other in terms of energy, economy, exergy, and environment (4E) and the goal is to fully supply the thermal and electrical load of the desired building. The studied criteria are electrical power and heat recovery, payback time (PBT), exergy efficiency, and saved carbon dioxide (SCD) from the energy, economic, exergy, and environmental point of view, respectively. Finally, it is concluded that in cold weather, the BIPVT system can achieve a 7.15% improvement in produced power compared to the BIPV system and 52.2% of the building’s heating needs are provided. It also causes the exergy efficiency to improve by an average of 1.69% and saves 34.98 ton of carbon dioxide. The PBT of this study is calculated as 5.77 years for the BIPV system and 4.78 years for the BIPVT system.
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Mehrdad, Sina, Reza Dadsetani, Alireza Amiriyoon, Arturo S. Leon, Mohammad Reza Safaei, and Marjan Goodarzi. "Exergo-Economic Optimization of Organic Rankine Cycle for Saving of Thermal Energy in a Sample Power Plant by Using of Strength Pareto Evolutionary Algorithm II." Processes 8, no. 3 (2020): 264. http://dx.doi.org/10.3390/pr8030264.
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Waste heat recovery plays an important role in energy source management. Organic Rankine Cycle (ORC) can be used to recover low-temperature waste heat. In the present work a sample power plant waste heat was used to operate an ORC. First, two pure working fluids were selected based on their merits. Four possible thermodynamic models were considered in the analysis. They were defined based on where the condenser and evaporator temperatures are located. Four main thermal parameters, evaporator temperature, condenser temperature, degree of superheat and pinch point temperature difference were taken as key parameters. Levelized energy cost values and exergy efficiency were calculated as the optimization criteria. To optimize exergy and economic aspects of the system, Strength Pareto evolutionary algorithm II (SPEA II) was implemented. The Pareto frontier solutions were ordered and chose by TOPSIS. Model 3 outperformed all other models. After evaluating exergy efficiency by mixture mass fraction, R245fa [0.6]/Pentane [0.4] selected as the most efficient working fluid. Finally, every component’s role in determining the levelized energy cost and the exergy efficiency and were discussed. The turbine, condenser and evaporator were found as the costliest components.
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Kostov, Konstantin. "DETERMINATION OF TECHNICAL AND ECONOMIC INDICATORS OF THERMAL POWER STATIONS DIRECTLY FROM THE TURBINE REGIME CHARACTERISTICS." EUREKA: Physics and Engineering 4 (July 31, 2020): 51–59. http://dx.doi.org/10.21303/2461-4262.2020.001358.
Full textAbstract:
The distribution of costs for electricity and heat production is accomplished by a number of fairly conditional methods. Cost analysis and allocation must be carried out on the basis of objective technical and economic criteria. The application of a method is determined by the introduced regulatory frameworks, energy markets and the prices of energy products. There are two fundamental methods – "physical" and "exergy". The physical method is based on the distribution of costs, and the exergy on the second law of thermodynamics. The article reviews and analyzes the tariff policy of the Thermal power plant. Objective criteria have been identified to serve as a means of forecasting and controlling fuel consumption. The thermal efficiency of a Thermal power plant has been evaluated. A comparison was made with similar Thermal power plants. A fundamentally new approach is proposed to determine the main technical and economic criteria of the plant. The proposed method allows determining indicators that uniquely characterize the thermal and economic efficiency of the plant without the need for diversification of fuel costs
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Fialko, N., A. Stepanova, R. Navrodska, N. Meranova, and S. Shevchuk. "COMPARATIVE ANALYSIS OF EXERGETIC EFFICIENCY OF HEAT RECOVERY SYSTEMS OF BOILER PLANTS." Energy and automation 2023, no. 3 (2023): 17–27. http://dx.doi.org/10.31548/energiya3(67).2023.017.
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The paper presents the results of a comparative analysis of the exergetic efficiency of heat recovery systems of boiler plants. The need to ensure the efficient operation of heat recovery systems for various purposes determines the importance and relevance of research conducted in this field. The purpose of the work is to increase the exergetic efficiency of heat recovery systems of various purposes. The results of solving the tasks necessary to achieve the set goal are given: - submit heat utilization systems of various purposes in the form of structural diagrams with the identification of exergetic flows of heat carriers; - choose exergetic efficiency evaluation criteria for heat recovery systems of various purposes, calculate their values and conduct a comparative analysis; - develop recommendations for the use of heat recovery systems for various purposes, taking into account the specifics of their application. For research, a complex methodology was used, which combines structural-variant methods of exergetic analysis with methods of presenting exergetic balances in matrix form. Three types of heat recovery systems with different numbers of consumers of recovered heat were considered. Structural diagrams of heat recovery systems of various purposes with identification of exergetic flows of heat carriers between individual discrete elements have been developed. Exergetic losses, thermal exergetic criterion and exergetic efficiency were selected as criteria for evaluating exergetic efficiency. Their values were obtained for heat recovery systems and their elements at different values of the relative power of the boiler. The largest exergy losses occur in the water-heating heat exchanger, smoke extractor and pumping system, the smallest - in the air-heating heat exchanger and gas heater. An increase in the relative power of the boiler leads to an increase in the relative contribution of the exergy losses of the water heating heat recovery system, as well as the pumping system and the pipeline system to the total exergy losses in the heat recovery system. It has been established that increasing the number of consumers of recovered heat in the heat recovery system and using rational ways of reducing total exergy losses increases the efficiency of heat recovery systems. Further developments in this field will allow to increase the exergetic efficiency of heat recovery systems for various purposes.
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Mitovski, Milance, and Aleksandra Mitovski. "Efficiency of the process of cryogenic air separation into the components." Chemical Industry 63, no. 5 (2009): 397–405. http://dx.doi.org/10.2298/hemind0905397m.
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The separation process of atmospheric air into its components by means of cryogenic low-pressure procedure, which takes place in the Oxygen plant in the Copper Mining and Smelting Complex, yields various products of different quantities and purities. Proper assessment of the energy consumption, hence assignments production cost of individual products may present considerable problem. For that goal, the least invested technical operation was adopted as criteria, and was restrained for all costs of production and distribution of specific energy. Case study was carried out in the Oxygen factory by monitoring producing parameters for the process in the 2007 year. Based on the monitoring of production parameters and their costs for 20 months in the period 2004-2005, correlation equations for power consumption in the total monthly amount and per mass of produced gaseous oxygen were created. The energy and exergy efficiency of the air separation process into the components are expressed as the ratio of input and useful energy and exergy of the process. On the basis of the adopted criteria, the assignments of energy consumption and production costs for cryogenic air separation process into the components are as follows: 82.59% for gaseous oxygen, 14.04% for liquid oxygen, 1.39% for gaseous nitrogen and 1.98% for liquefied nitrogen. The air separation efficiency is achieved in the amount of energy 0.0872-0.1179 and exergy 0.0537-0.1247. Power consumption per mass of the products in 2007 year is 1325.059 kWh/t of liquid oxygen, 828.765 kWh/t of liquid nitrogen, 429.812 kWh/t of gaseous oxygen and 309.424 kWh/t of nitrogen gas. Production costs of the technical gases at the dawn of the factory are: 6730.69 RSD/t of liquid oxygen, 4209.74 RSD/t of liquid nitrogen, 2183.25 RSD/t of gaseous oxygen and 1571.73 RSD/t of gaseous nitrogen.
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Mishra, Punit, Shubham Soni, and Govind Maheshwari. "Thermodynamic Analysis of Split Air Conditioner Using Energy and Exergy Viewpoint with Low GWP Refrigerants Alternative to R410A." E3S Web of Conferences 309 (2021): 01141. http://dx.doi.org/10.1051/e3sconf/202130901141.
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In this paper, a comparative thermodynamic analysis on energy and exergy viewpoint is done on different low global warming potential (GWP) refrigerants to find the possible alternative of high GWP refrigerant R410A. R410A is used nowadays in air conditioning systems due to its ozone-friendly characteristic as zero ozone depletion potential (ODP=0) but it has high GWP (GWP=1924) that leads to global warming. Now a day’s global warming is considered to be one of the critical aspects when environmental protection is taken into consideration and researchers from every corner of the globe are working to find refrigerants that not only have zero ODP but it has low GWP too. In this analysis, four prospect refrigerants namely R32, R447A, R447B, and R452B have been studied to find their suitability to replace R410A on different performance criteria as the coefficient of performance (COP), power consumption, exergy efficiency, and exergy destruction. Thermodynamic properties of the studied refrigerants have been taken from the Genetron Properties 1.4 software. The result indicates that all the studied refrigerants have better performance characteristics compared to R410A but R447A has maximum COP and exergy efficiency along with the least total exergy destruction that makes it a possible alternate of R410A.
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Joseph, B. Bassey, and Odesola Isaac. "Power Generation Systems Assessment: A New Approach." Engineering and Technology Journal 9, no. 07 (2024): 4364–77. https://doi.org/10.5281/zenodo.12678542.
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Power generation systems have become useful for grid base and off grid electric power generation. Hence, its performance has become critical for sustainable growth and development. Performance evaluation of power generation systems has always been carried out using the independent assessment approach (IAA) whose models are: the reliability, availability, emission characteristics, energy and exergy efficiency. The IAA approach only assesses the system performance in part without recur to other indexes, hence, limiting a holistic view of the true plant state. In this paper, the development of a new performance index using the combined assessment approach (CAA) is explored. This approach (CAA) seeks to combine two relatable traditional measures for the assessment of power generation system. The model combines exergy efficiency and reliability measures for analysis. First Independent Power Limited (FIPL) gas turbine power plant was used to test the model. The plant reliability and availability were evaluated along with its thermal efficiency using the exergy model. The analysis of plant thermal efficiency was carried out using the steady state model. Results of the traditional indexes of the plant were compared with the proposed (<strong>Bassy-II</strong> index) index. It was seen that the new index provided a new assessment criteria. The exergy efficiency, reliability and availability measures indicated a fairly rated plant state. However, the new index defined a new plant state which is unique and represents the true status of the system in whole. Hence, the proposed index (<strong>Bassy-II</strong> index) is recommended for use in the holistic assessment of power generation systems.
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Thaddaeus, Julius. "Exergy and economic assessments of an organic rankine cycle module designed for heat recovery in commercial truck engines." Indian Journal of Science and Technology 13, no. 37 (2020): 3871–83. http://dx.doi.org/10.17485/ijst/v13i37.1299.
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Objectives: To evaluate the energy and exergy performances of a designed ORC system and to quantify loses within the system and measure its output.The study also assesses the economic performance of the ORC system to determine the feasibility of the business. Methods: Thermodynamic analysis assessing the energy performance and cost estimation using manufacturers’ prices to generate generic equations for estimating costs of the components of the designed ORC system. Findings: The results of the exergy evaluation of the ORC show a system thermal efficiency of 6.39%, net power output of 3.10kWe, exergy destruction of 9.07kW, and exergy efficiency of 54.6%. The economic estimation has a capital investment cost of £8,381.98, a specific investment cost of £2,754.36/kWe, annual savings of £1,233.34, and a payback period of 6.8years. Novelty: The use of exergetic method of analysis and the assessment of the potential economic benefits of installing the module in commercial trucks which form part of the acceptance-criteria, using prevailing market prices of the ORC system is an obvious novelty in this study. In addition, the generation and use of curve-fitting plots to obtain the generic equations for computing the approximate costs of the individual components of the system is an integral part of the novelty of this work. Keywords: Organic Rankine cycle; exergy and economic assessment; specific investment cost; capital investment cost; payback period; exhaust heat recovery
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Javaherian, Amirreza, Sadaf Ghasemi, Seyed Mohammad Seyed Mahmoudi, Marc A. Rosen, and Mohsen Sadeghi. "Two-Objective Optimization of a Cogeneration System Based on a Gas Turbine Integrated with Solar-Assisted Rankine and Absorption Refrigeration Cycles." Sustainability 15, no. 21 (2023): 15624. http://dx.doi.org/10.3390/su152115624.
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The current study investigates a cogeneration system based on a gas turbine, integrated with a Rankine cycle and an absorption refrigeration cycle, considering energy and exergy perspectives. The fuel used in the gas turbine’s combustion chamber is obtained through biomass gasification, specifically using wood as the biomass fuel. To enhance the system’s performance, solar energy is utilized to preheat the working fluid in the Rankine cycle, reducing the energy required in the heat recovery steam generator. Additionally, an absorption refrigeration cycle is incorporated to recover waste heat from exhaust gases and improve the plant’s exergy efficiency. A two-objective optimization is conducted to determine the optimal operating conditions of the proposed system, considering exergy efficiency and carbon dioxide emission index as criteria. The case study reveals that the gasifier and combustion chamber contribute the most to system irreversibility, accounting for 46.7% and 22.9% of the total exergy destruction rate, respectively. A parametric study is performed to assess the impact of compression ratio, turbine bleed steam pressure, gas turbine inlet temperature, and solar share (the ratio of energy received by solar collectors to biomass fuel input energy) on system performance. The findings demonstrate that maximum energy and exergy efficiencies of the power generation system are achieved at a pressure ratio of 10. Furthermore, a 1% reduction in the gas turbine’s compression pressure ratio can be compensated by a 9.3% increase in the solar share within the steam Rankine cycle.
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Marchenko, A. P., S. S. Kravchenko, O. M. Bekaryuk, and M. S. Shelestov. "APPLICATION OF EXERGETIC METHOD FOR EVALUATION OF PROCESS PERFECTION IN DIESEL ENGINE SUPERCHARGING SYSTEM." Internal Combustion Engines, no. 2 (July 26, 2021): 24–30. http://dx.doi.org/10.20998/0419-8719.2021.2.03.
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One of the most important trends of the modern combat vehicles is increasing their mobility for the security of the crew and for fast movement in different types of terrain. Compliance with these criteria is ensured by the engine of the armored vehicle. The competitiveness of domestic engines for armored vehicles should be ensured by the creation of new structures, their constant modernization and further improvement of performance. One of such engines is a forced diesel engine 6DN12/2x12 with a capacity of 1100 kW. In order to improve its performance and increase the level of forcing, it is proposed to improve the air supply system of the engine. Evaluating the effectiveness of the system can identify nodes that need changing design parameters. Therefore, such a qualitative analysis also indicates the feasibility and the possibility of further modernization of the system design. The qualitative analysis of the turbocharger is carried out on the basis of exergy method, which allows identifying sources of energy losses in the system design and determines the degree of perfection of processes. The application of the exergy method is due to the purpose of determining the reserves to improve the efficiency of the turbocharger elements, the magnitude of the supplied exergy and exergy efficiency in the nodes of the air supply system. According to the method, an exergy scheme of the supercharging system was constructed, on the basis of which the energy-exergy balance of each compressor unit was derived. The results of the analysis allowed to determine the parameters of the flow of the working fluid in the characteristic sections of the compressor and turbine and exergetic efficiency of the supercharging system. The calculated data obtained by exergetic analysis provide an estimate of the distribution of energy losses and allow determining the areas for further improvement of the air supply system and providing an opportunity to choose such design parameters that achieve the most effective improvement of the system.
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López, González Eduardo, LLERENA FERNANDO ISORNA, and Iglesias Felipe Rosa. "Optimization of a solar hydrogen storage system: Exergetic considerations." International Journal of Hydrogen Energy 32 (November 28, 2006): 1537–41. https://doi.org/10.1016/j.ijhydene.2006.10.032.
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From production to end-users, the choice of suitable hydrogen delivery and storage systems will be essential to assure the adequate introduction and development of these facilities. This article describes the main options for hydrogen storage when produced from renewable energy, and explains different criteria to be considered in the design and building-up of stationary hydrogen storage systems, with special attention to exergy issues. An example of exergy analysis is done using data from the solar hydrogen storage facility of the Spanish Instituto Nacional de Técnica Aeroespacial (INTA).As expected, the main conclusions of this analysis show the advantage of low pressure hydrogen in comparison with other available methods to store hydrogen. Another interesting option, from the exergy efficiency point of view, is the storage of hydrogen in metal hydride systems.The last option, and the most inefficient, is the high pressure hydrogen storage.
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Julius, Thaddaeus, O. Unachukwu Godwin, A. Mgbemene Chigbo, Pesyridis Apostolos, and Aziz Alshammari Fuhaid. "Exergy and economic assessments of an organic rankine cycle module designed for heat recovery in commercial truck engines." Indian Journal of Science and Technology 13, no. 37 (2020): 3871–83. https://doi.org/10.17485/IJST/v13i37.1299.
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Abstract <strong>Objectives:</strong> To evaluate the energy and exergy performances of a designed ORC system and to quantify loses within the system and measure its output.The study also assesses the economic performance of the ORC system to determine the feasibility of the business. <strong>Methods:</strong> Thermodynamic analysis assessing the energy performance and cost estimation using manufacturers’ prices to generate generic equations for estimating costs of the components of the designed ORC system.<strong> Findings:</strong> The results of the exergy evaluation of the ORC show a system thermal efficiency of 6.39%, net power output of 3.10kWe, exergy destruction of 9.07kW, and exergy efficiency of 54.6%. The economic estimation has a capital investment cost of £8,381.98, a specific investment cost of £2,754.36/kWe, annual savings of £1,233.34, and a payback period of 6.8years. <strong>Novelty:</strong> The use of exergetic method of analysis and the assessment of the potential economic benefits of installing the module in commercial trucks which form part of the acceptance-criteria, using prevailing market prices of the ORC system is an obvious novelty in this study. In addition, the generation and use of curve-fitting plots to obtain the generic equations for computing the approximate costs of the individual components of the system is an integral part of the novelty of this work. <strong>Keywords:</strong> Organic Rankine cycle; exergy and economic assessment; specific investment cost; capital investment cost; payback period; exhaust heat recovery
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Açikkalp, Emin. "Models for optimum thermo-ecological criteria of actual thermal cycles." Thermal Science 17, no. 3 (2013): 915–30. http://dx.doi.org/10.2298/tsci110918095a.
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In this study, the ecological optimization point of irreversible thermal cycles (refrigerator, heat pump and power cycles) was investigated. The importance of ecological optimization is to propose a way to use fuels and energy source more efficiently because of an increasing energy need and environmental pollution. It provides this by maximizing obtained (or minimizing supplied) work and minimizing entropy generation for irreversible (actual) thermal cycles. In this research, ecological optimization was defined for all basic irreversible thermal cycles, by using the first and second laws of thermodynamics. Finally, the ecological optimization was defined in thermodynamic cycles and results were given to show the effects of the cycles? ecological optimization point, efficiency, COP and power output (or input), and exergy destruction.
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Shchinnikov, P. A., O.V. Borush, S.V. Zykov, and A.I. Mikhaylenko. "Optimal Solutions for Load Sharing between Units of a Combined Heat and Power Plant." Problemele Energeticii Regionale 3(35) (December 15, 2017): 25–32. https://doi.org/10.5281/zenodo.1188781.
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The article presents the optimization method of load division between combined heat and power plant units. The method used the power unit division into functioning parts and the differentialexergy method. This method allowed presenting the unit as a structural diagram where exergetic subsystems are fuel supply, steam generator, turbine, generator and electrical equipment, water supply and regeneration, heat supply to the consumer. The differential-exergy method was based on a combination of exergy analysis and optimization method of economic efficiency criteria using uncertain Lagrange multipliers. The use of the exergy function of goal allowed avoiding the problem of division of fuel costs for each type of product that was important at optimization. The optimization criterion, its parameters and limitations were developed as well. These parameters can extend traditional technical and economic analysis of the combined heat and power plants operating mode, as they take into account thermodynamically rigorous division of fuel costs between heat and electric power at their complex production on the combined heat and power plants. The use of the differentialexergy method in optimizing the load distribution of the power units of the combined heat and power plants makes possible obtaining of fuel savings of 1.5 to 3%. It has been shown that if the parameters of power units deteriorate, the application of the method makes it possible to have the best performance of the power plant when it is compared with functioning of combined heat and power units at proportional loading.
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Golpour, Iman, Mohammad Kaveh, Ana M. Blanco-Marigorta, et al. "Multi-Response Design Optimisation of a Combined Fluidised Bed-Infrared Dryer for Terebinth (Pistacia atlantica L.) Fruit Drying Process Based on Energy and Exergy Assessments by Applying RSM-CCD Modelling." Sustainability 14, no. 22 (2022): 15220. http://dx.doi.org/10.3390/su142215220.
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The present investigation aimed to perform an optimisation process of the thermodynamic characteristics for terebinth fruit drying under different drying conditions in a fluidised bed-infrared (FBI) dryer using response surface methodology (RSM) based on a central composite design (CCD) approach. The experiments were conducted at three levels of drying air temperature (40, 55, and 70 °C), three levels of drying air velocity (0.93, 1.765, and 2.60 m/s), and three levels of infrared power (500, 1000, and 1500 W). Energy and exergy assessments of the thermodynamic parameters were performed based on the afirst and second laws of thermodynamics. Minimum energy utilisation, energy utilisation ratio, and exergy loss rate, and maximum exergy efficiency, improvement potential rate, and sustainability index were selected as the criteria in the optimisation process. The considered surfaces were evaluated at 20 experimental points. The experimental results were evaluated using a second-order polynomial model where an ANOVA test was applied to identify model ability and optimal operating drying conditions. The results of the ANOVA test showed that all of the operating variables had a highly significant effect on the corresponding responses. At the optimal drying conditions of 40 °C drying air temperature, 2.60 m/s air velocity, 633.54 W infrared power, and desirability of 0.670, the optimised values of energy utilisation, energy utilisation ratio, exergy efficiency, exergy loss rate, improvement potential rate, and sustainability index were 0.036 kJ/s, 0.029, 86.63%, 0.029 kJ/s, 1.79 kJ/s, and 7.36, respectively. The models predicted for all of the responses had R2-values ranging between 0.9254 and 0.9928, which showed that they had good ability to predict these responses. Therefore, the results of this research showed that RSM modelling had acceptable success in optimising thermodynamic performance in addition to achieving the best experimental conditions.
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Ma, Kai, Xiaokun Wu, Huaican Liu, Dantong Li, and Zhilong He. "Theoretical and Numerical Research on High-Speed Small Refrigeration Twin-Screw Compressor." Applied Sciences 15, no. 7 (2025): 3742. https://doi.org/10.3390/app15073742.
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To investigate the performance of high-speed miniaturized screw refrigeration compressors, this study designed rotors with identical theoretical displacement but varying rated speeds. A normalized analysis established quantitative evaluation criteria for geometric performance, while an exergy analysis model assessed leakage exergy losses. Thermodynamic modeling evaluated the impact of different clearances and rated speeds on performance. Computational fluid dynamics (CFD) simulations analyzed the gas forces and torque acting on the rotors. The rate of efficiency improvement with increasing speed follows a non-linear relationship, demonstrating diminishing returns at ultra-high speeds, where further speed elevation provides negligible efficiency gains. This study reveals that, while tip-housing leakage represents the largest volumetric leakage in screw compressors, interlobe leakage contributes the most significantly to power losses. When the rated speed increases from 3000 rpm to 15,000 rpm, interlobe leakage remains the dominant source of power loss, with its relative contribution showing a marked increase. For compressors with identical cylinder dimensions, reducing the number of lobes decreases the discharge pressure fluctuations and power consumption. Larger wrap angles increase the contact line length and discharge port area, reducing the volumetric efficiency while creating a trade-off between leakage and discharge losses, resulting in an optimal wrap angle that maximizes the adiabatic efficiency.
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Romaniuk, V. N., and A. M. Niyakovski. "Scientific and Methodological Bases of Exergetic Analysis of the Processes of Heat Treatment of Concrete Products in Heat Technology Installations. Part 2." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 64, no. 4 (2021): 328–35. http://dx.doi.org/10.21122/1029-7448-2021-64-4-328-335.
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This article is the second part of the research devoted to the exergetic analysis of heat treatment processes of concrete products in heat technology installations. In the first part, the issues of calculating the exergy of a concrete mixture and hardening concrete have been considered, taking into account all the components of the exergy, viz. reaction, concentration and thermomechanical ones. In the present part of the study, exergetic criteria are proposed that make it possible to evaluate the energy efficiency of the operating modes of heat-technological equipment for the heat treatment of concrete products. These include the degree of thermodynamic perfection of a heat-power system, which is used to evaluate the completeness of the use of the exergetic input; thermodynamic efficiency of the system of heat treatment of concrete products in heat technology installations, representing the degree of thermodynamic perfection of the heat power system that is calculated without taking into account all the components of the sum of transit exergies; thermodynamic efficiency of the heat treatment system, taking into account the exergetic efficiency of the system of heat energy production and transportation; the degree of technological perfection that indicates at the portion of the exergy supplied to the heat technology installation for the heat treatment of concrete products is intended to obtain a technological result. To calculate the listed indicators and characteristics, a mathematical apparatus is proposed that takes into account the mass of the concrete product, the specific mass exergy of cement and hardening concrete, the specified degree of hydration of cement in concrete at the end of heat treatment, the exergetic flows supplied to the product in a heat technology installation during its heat treatment, and numerical indicators characterizing the incompleteness of the cement hydration process. The results obtained in this paper are discussed from the viewpoint of their applicability in the selection of heat treatment modes. They can be used in the selection of energy-saving modes of heat-technological equipment for industrial heat treatment of concrete products.
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Silva Ortiz, Pablo, Silvio de Oliveira, Adriano Pinto Mariano, Agnes Jocher, and John Posada. "Exergy-Based Improvements of Sustainable Aviation Fuels: Comparing Biorefinery Pathways." Processes 12, no. 3 (2024): 510. http://dx.doi.org/10.3390/pr12030510.
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The aeronautical sector faces challenges in meeting its net-zero ambition by 2050. To achieve this target, much effort has been devoted to exploring sustainable aviation fuels (SAF). Accordingly, we evaluated the technical performance of potential SAF production in an integrated first- and second-generation sugarcane biorefinery focusing on Brazil. The CO2 equivalent and the renewability exergy indexes were used to assess environmental performance and impact throughout the supply chain. In addition, exergy efficiency (ηB) and average unitary exergy costs (AUEC) were used as complementary metrics to carry out a multi-criteria approach to determine the overall performance of the biorefinery pathways. The production capacity assumed for this analysis covers 10% of the fuel demand in 2020 at the international Brazilian airports of São Paulo and Rio de Janeiro, leading to a base capacity of 210 kt jet fuel/y. The process design includes sugarcane bagasse and straw as the feedstock of the biochemical processes, including diverse pre-treatment methods to convert lignocellulosic resources to biojet fuel, and lignin upgrade alternatives (cogeneration, fast pyrolysis, and gasification Fischer-Tropsch). The environmental analysis for all scenarios shows a GHG reduction potential due to a decrease of up to 30% in the CO2 equivalent exergy base emissions compared to fossil-based jet fuel.
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Tavana, Mashar, Mahdi Deymi-Dashtebayaz, Daryoush Dadpour, and Behnam Mohseni-Gharyehsafa. "Realistic Energy, Exergy, and Exergoeconomic (3E) Characterization of a Steam Power Plant: Multi-Criteria Optimization Case Study of Mashhad Tous Power Plant." Water 15, no. 17 (2023): 3039. http://dx.doi.org/10.3390/w15173039.
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This paper presents an in-depth investigation into the performance of Mashhad Tous power plant in Iran, a natural-gas-fueled steam cycle with an output power of 4 × 150 MW. The analyses include energy, exergy, and exergoeconomic. To facilitate the study, a robust code is developed to simulate the thermodynamic topology of the power plant. The fidelity of the simulation is validated using realistic site conditions. The study incorporates three vital decision variables: boiler water mass flow rate, turbine inlet pressure from, and ambient temperature ranging from 90 kg⋅s−1 to 150 kg⋅s−1, 12 MPa to 19 MPa, and 10 °C to 40 °C, respectively. Three different heat loads, including 423 MW, 311 MW, and 214 MW, are used to analyze the performance of the power plant. A Pareto-based multi-criteria optimization intertwined with the technique for order of preference by similarity to the ideal solution (TOPSIS) is used to find the optimum conditions in terms of having the highest work output and exergy efficiency while simultaneously reducing the plant’s total cost. The optimization results demonstrate a 4.28% increase in output at full load (423 MW). Additionally, a 1.52% increase is observed at partial load (311 MW), and there is a notable 16% increase in output at low load (214 MW). These improvements also positively impacted energy efficiency. Specifically, there is a 4% improvement at full load, a 0.9% enhancement at partial load, and a remarkable 5.4% increase in energy efficiency at low load. In terms of costs, substantial reductions of 37% at full load, 31% at partial load, and an impressive 72% at low load are evident.
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Koroleva, L. A., A. G. Khaydarov, G. K. Ivakhnyuk, and Yu E. Akterskiy. "Using the flammability potential and the exergy indicator to assess the fire hazard of the rail transportation of cargoes." Pozharovzryvobezopasnost/Fire and Explosion Safety 30, no. 1 (2021): 16–31. http://dx.doi.org/10.22227/pvb.2021.30.01.16-31.
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Introduction. Problems of fire safety of dangerous goods (DG) in the process of their rail transportation have not been fully resolved. The flammability assessment of substances and materials is insufficiently impartial; an integrated indicator, that allows to apply a consolidated methodological standpoint to improve their energy efficiency and environmental/fire safety is unavailable.The purpose of this work is to substantiate the feasibility and advantages of the exergy approach to assessing the fire hazard of the exhaust gas emitted from railroad transport.Materials and methods. The use of the flammability potential as an integrated indicator of the fire hazard of cargoes has a number of limitations. The exergy approach has a strong potential if applied to the assessment and prediction of fire hazards. Present-day and potential railroad cargoes serve as examples that substantiate the feasibility of this approach.Results and its discussion. Dependences between fire hazard indicators (flash points, flame propagation limits, auto-ignition points, heat of combustion) demonstrated by the components of liquid and gaseous fuels and the chemical exergy were identified.A study of changes in the physical exergy triggered by spills and combustion were illustrated by liquefied natural gas and liquefied hydrocarbon gases having various compositions. Physical exergy change patterns depending on the temperature and pressure of the above products were developed.For self-ignitable cargoes, dependences between the physical exergy and activation energy, critical ambient temperature, and heat capacity of self-heating materials were identified. The influence of thermal conductivity and humidity coefficients on the exergy value is established.Exergy changes were determined depending on the elemental composition of solid municipal waste, ash, volatile matter and fixed carbon content. Polymers and rubbers have the highest values of this indicator.An exergy indicator was introduced to assess fire and environmental hazards of substances and materials; it serves as the basis for the classification of cargoes.Conclusions. The use of the exergy indicator allows to increase the objectivity of assessments and take account of technical, economic, environmental criteria and indicators of fire hazards within an integrated system.
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Weber, Samanta A., Dirk Volta, and Jürgen Kuck. "Comparison of the Energetic Efficiency of Gas Separation Technologies Using the Physical Optimum by the Example of Oxygen Supply Options." Energies 15, no. 5 (2022): 1855. http://dx.doi.org/10.3390/en15051855.
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This study applies the Physical Optimum (PhO) as a reference value to rate the efficiency of two technical options for the oxygen supply of a hospital. The systematic comparison of the alternative processes using the PhO as a benchmark for the minimum input (exergy in this case) required to run a process with a certain benefit allows to determine the potential for optimization of each technology. Differences are analyzed by visualizing the losses of each individual production step in a process as well as by the resulting overall energy demand, including the primary energy. Possible alternatives are purchasing liquid oxygen from a cryogenic process or the production by means of Pressure Swing Adsorption (PSA) on site. The cryogenic production shows a lower exergy demand even though it also has a higher potential for optimization. Yet, the total losses, significantly impacted by the unavoidable transportation, sum up, resulting in the conclusion that the PSA is the preferable option overall, considering energy aspects. Finally, additional criteria such as economic, legal, and structural consequences of the respective choices are briefly outlined.