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Thermodynamic Performance Comparison and Optimization of sCO_(2)Brayton cycle,tCO_(2)Brayton cycle and tCO_(2)rankine cycle

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Journal of Thermal Science 2023年第2期32卷 611-627页

作者： JIANG Yu ZHAN Li TIAN Xuelian NIE Changhua Nuclear Power Institute of China Chengdu 610213China

In this paper,to further improve thermodynamic performance of supercritical carbon dioxide cycle,simple/recompression transcritical carbon dioxide Brayton cycle(STBC/RTBC)and simple/recompression transcritical carbon dioxide rankine cycle(STRC/RTRC)are *** and exergy performance analysis and optimization for the above four transcritical CO_(2)cycles and simple/recompression supercritical cycle(SSBC/RSBC)are *** effect of key thermodynamic parameters on those CO_(2)cycle performance is *** indicate that the improvements of thermodynamic performance of CO_(2)cycle are obvious when transcritical Brayton and rankine cycle are applied in *** the same range of optimization variables,the maximum thermal efficiency improvements of RTRC and RTBC are 4.98%and 3.6%,and maximum exergy efficiency improvements of RTRC and RTBC are 7.08%and 5.13%when compared with ***,the thermodynamic performances of STBC and STRC are also outstanding than that of *** work provides a way to further improve the thermodynamic performance of CO_(2)power cycle.

关键词： thermodynamic performance supercritical carbon dioxide transcritical carbon dioxide Brayton cycle rankine cycle

Influence of Temperature Difference Calculation Method on the Evaluation of rankine cycle Performance

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Journal of Thermal Science 2014年第1期23卷 68-76页

作者： Takafumi.Morisaki Yasuyuki.Ikegami Graduate School of Science and Engineering.Saga University Institute of Ocean Energy Saga University

In the new century, energy and environmental problems are becoming more critical, and the development of natural energy is desired. Low-grade Thermal Energy Conversion(LTEC) is refocused as one of the renewable energy methods. The usefulness of LTEC is expected using hot springs and waste heat. In the case of the rankine cycle using ammonia as the working fluid, the thermal properties of the working fluid changes in the evaporator. The traditional evaluation method of heat exchanger performance is the LMTD(Logarithmic Mean Temperature Difference) method. On the other hand, the GMTD(Generalized Mean Temperature Difference) method allows the variation of thermal properties in the heat exchanger. The aim of this study is to compare the two methods for the calculation of temperature differences and the corresponding influence on the total performance of the rankine cycle that is operated using ammonia as a working fluid. As a result, the thermal efficiency of the rankine cycle is greater than that of the LMTD method. Moreover, the computable range of the GMTD calculation method is less than that of the LMTD calculation method.

关键词： GMTD LMTD LTEC OTEC rankine cycle

A Viable Megawatt-Class Space Power Plant under rankine cycle

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Journal of Energy and Power Engineering 2012年第5期6卷 683-694页

作者： Ramon Ferreiro Garcia Department of Industrial Engineering University of A Coruna .4 Coruna 15011 Spain

The aim of the article concerns to the achieved research results regarding the viability of a megawatt-class space power plant based on the rankine cycle for which the main objectives are to highlight the key issues responsible for improving the rankine cycle efficiency. Two working fluids are studied （water and ammonia） on the basis of its well known characteristics. cycles operating under top and bottom temperatures approaching the state of the art technology associated to cooling fluid reservoirs are key to improve the efficiency. With such strategy, the achieved thermal efficiency increases more than 20% with respect to conventional power plants. Mentioned benefits associated to the strategy based on the reduction of the required payload capacity, the condenser radiation surface and the power plant mass represent the main advantages of the proposed innovation techniques.

关键词： Concentrated solar power cycle efficiency energy conversion organic rankine cycle rankine cycle solar dynamicpower system.

Machine learning-based multi-objective optimization and thermal assessment of supercritical CO_(2) rankine cycles for gas turbine waste heat recovery

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Energy and AI 2024年第2期16卷 363-384页

作者： Asif Iqbal Turja Ishtiak Ahmed Khan Sabbir Rahman Ashraf Mustakim Mohammad Ishraq Hossain M Monjurul Ehsan Yasin Khan Department of Mechanical and Production Engineering(MPE) Islamic University of Technology(IUT)Board BazarGazipur1704Bangladesh

Technologies for utilizing waste heat for power generation have attracted significant attention in recent years due to their potential to enhance energy efficiency and reduce greenhouse gas *** research focuses on the comparative and optimization analysis of three supercritical carbon dioxide(sCO_(2))rankine cycles(simple,cascade,and split)for gas turbine waste heat *** study begins with parametric analysis,investigating the significant effects of key variables,including turbine inlet temperature,condenser inlet temperature,and pinch point temperature,on the thermal performance of advanced sCO_(2) power *** identify the most efficient cycle configuration,a multi-objective optimization approach is *** approach combines a Genetic Algorithm with machine learning regression models(Random Forest,XGBoost,Artificial Neural Network,Ridge Regression,and K-Nearest Neighbors)to predict cycle performance using a dataset extracted from cycle *** decision-making process for determining the optimal cycle configuration is facilitated by the TOPSIS(technique for order of preference by similarity to the ideal solution)*** study's major findings reveal that the split cycle outperforms the simple and cascade configurations in terms of power generation across various operating *** optimized split cycle not only demonstrates superior power output but also exhibits enhanced net power output,heat recovery,system and exergy efficiency of 7.99 MW,76.17%,26.86%and 57.96%,respectively,making it a promising choice for waste heat recovery *** research has the potential to contribute to the advancement and widespread adoption of waste heat recovery in energy technologies boosting system efficiency and economic *** provides a new perspective for future research,contributing to the improvement of energy generation infrastructure.

关键词： Supercritical co2 rankine cycle Waste heat recovery Gas turbine Thermodynamic analysis Machine Learning Optimization

Review on heat-to-power conversion technologies for hypersonic vehicles

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Chinese Journal of Aeronautics 2024年第5期37卷 148-179页

作者： Yinke QI Xiaofeng MA Peixue JIANG Yinhai ZHU Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Beijing Key Laboratory of CO_(2)Utilization and Reduction Technology Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China

Hypersonic vehicles have enormous military and economic value,while their power and thermal protection demands will increase substantially with the rise in Mach number and *** the tremendous high-quality heat on the vehicle surface and engine wall into electrical energy through heat-to-power technologies will not only play a role in thermal protection,but also supply power for the *** paper provides a comprehensive review of heat-to-power conversion technologies on hypersonic vehicles,including the indirect conversion of Brayton and rankine cycles,direct conversion of thermoelectric materials,and combined *** the open Brayton cycle with hydrocarbon fuel as the working fluid,the Power-to-Weight Ratio(PWR)can achieve the highest,at around 1.8,due to the high PWR of the hydrocarbon fuel turbine and the few components of the ***,its work capacity is limited by the flow rate of the supplied *** closed Brayton cycle can maintain a relatively high PWR,ranging from 0.2 to 0.8,while achieving relatively high output power and conversion *** rankine cycle has a higher PWR,its range is close to that of the closed Brayton cycle,peaking at about *** thermoelectric materials technology has a small power generation level,making it more suitable for scenarios with low power *** review provides a basis for selecting and developing heat-to-power conversion technologies on hypersonic vehicles.

关键词： Hypersonic vehicles Heat-to-power conversion Brayton cycle rankine cycle Thermoelectric materials

A review of cryogenic power generation cycles with liquefied natural gas cold energy utilization

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Frontiers in Energy 2016年第3期10卷 363-374页

作者： Feier XUE Yu CHEN Yonglin JU Institute of Refrigeration and Cryogenics Shanghai Jiao Tong University Shanghai 200240 China College of Mechanical Engineering Shanghai University of Engineering Science Shanghai 201620 China

Liquefied natural gas （LNG）, an increasingly widely applied clean fuel, releases a large number of cold energy in its regasification process. In the present paper, the existing power generation cycles utilizing LNG cold energy are introduced and summarized. The direction of cycle improvement can be divided into the key factors affecting basic power generation cycles and the structural enhancement of cycles utilizing LNG cold energy. The former includes the effects of LNG-side parameters, working fluids, and inlet and outlet thermodynamic parameters of equipment, while the latter is based on rankine cycle, Brayton cycle, Kalina cycle and their compound cycles. In the present paper, the diversities of cryogenic power generation cycles utilizing LNG cold energy are discussed and analyzed. It is pointed out that further researches should focus on the selection and component matching of organic mixed working fluids and the combination of process simulation and experi- mental investigation, etc.

关键词： liquefied natural gas (LNG) cold energy,power generation cycle rankine cycle compound cycle

Design and Optimization of a Full-Generation System for Marine LNG Cold Energy Cascade Utilization

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Journal of Thermal Science 2020年第3期29卷 587-596页

作者： SUN Xiaofei YAO Shouguang XU Jinjin FENG Guozeng YAN Likun School of Energy and Power Engineering Jiangsu University of Science and TechnologyZhenjiang 21200China

This paper took a 100,000 DWT LNG fuel powered ship as the research *** on the idea of"temperature matching,cascade utilization"and combined with the application conditions of the ship,a horizontal three-level nested rankine cycle full-generation system which combined the high-temperature waste heat of the main engine flue gas with the low-temperature cold energy of LNG was proposed in this ***,based on the analysis and selection of the parameters which had high sensitivity to the system performance,the parameters of the proposed system were optimized by using the genetic *** optimization,the exergy efficiency of the marine LNG gasification cold energy cascade utilization power generation system can reach 48.06%,and the thermal efficiency can reach 35.56%.In addition,this paper took LNG net power generation as the performance index,and compared it with the typical LNG cold energy utilization power generation system in this *** results showed that the unit mass flow LNG power generation of the system proposed in this paper was the largest,reaching 457.41 k W.

关键词： LNG cold energy utilization CO2 transcritical rankine cycle genetic algorithm

Comparison and Optimization of Mid-low Temperature Cogeneration Systems for Flue Gas in Iron and Steel Plants

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Journal of Iron and Steel Research International 2013年第11期20卷 33-40页

作者： ZHANG Li-hua WU Li-jun ZHANG Xiao-hong JU Gui-dong Thermal and Environmental Engineering Institute Tongji University Resources and Environment Department Shandong Water Polytechnic

Three generation systems, namely, steam rankine cycle （SRC）, organic rankine cycle （ORC）, and steam-organic combined rankine cycle （S-ORC）, were simulated using the Engineering Equation Solver fEES） to efficiently utilize flue gas emissions from 200 to 450 ℃ in iron and steel plants. Based on the simulation results for thermal efficiency, exergy efficiency, and power generation, the performances of the three power generation systems were compared and analyzed. To further utilize waste heat from the turbine exhaust steam of the ORC system, cas- cade （）RC （CORC） was designed for heat sources above 300 ℃. Based on a comprehensive performance comparison, the application of the ORC using R141b is preferable for 200 to 300 ℃ flue gas. For 300 to 450 ℃ flue gas, CORC is an alternative technology to improve the efficiency and quality of waste heat utilization. For flue gas above 450 ℃, S-ORC can achieve higher efficiency and power generation than conventional SRC, with a relatively small negative pressure and high dryness of the turbine outlet steam. Hence, S-ORC can be considered as a substitute for SRC.

关键词： mid-low temperature flue gas rankine cycle thermal energy recovery generation system

Dual Pressure versus Hybrid Recuperation in an Integrated Solid Oxide Fuel Cell cycle--Steam cycle

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Journal of Energy and Power Engineering 2014年第4期8卷 596-611页

作者： Masoud Rokni Department of Mechanical Engineering Technical University of Denmark Lyngby 2800 Denmark

A SOFC （solid oxide fuel cell） cycle running on natural gas was integrated with a ST （steam turbine） cycle. The fuel is desulfurized and pre-reformed before entering the SOFC. A burner was used to combust the remaining fuel after the SOFC stacks. The off-gases from the burner were used to produce steam in a HRSG （heat recovery steam generator）. The bottoming steam cycle was modeled with two configurations：（1） a simple single pressure level and （2） a dual pressure level with both a reheat and a pre-heater. The SOFC stacks in the present SOFC-ST hybrid cycles were not pressurized. The dual pressure configuration steam cycle combined with SOFC cycle （SOFC-ST） was new and has not been studied previously. In each of the configuration, a hybrid recuperator was used to recovery the remaining energy of the off-gases after the HRSG. Thus, four different plants system setups were compared to each other to reveal the most superior concept with respect to plant efficiency and power. It was found that in order to increase the plant efficiency considerably, it was enough to use a single pressure with a hybrid recuperator instead of a dual pressure rankine cycle.

关键词： SOFC fuel cell hybrid cycle steam cycle rankine cycle hybrid recuperation.