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1
Wu, Pan, Chuntian Gao, Yanping Huang, Dan Zhang, and Jianqiang Shan. "Supercritical CO2 Brayton Cycle Design for Small Modular Reactor with a Thermodynamic Analysis Solver." Science and Technology of Nuclear Installations 2020 (January 24, 2020): 1–16. http://dx.doi.org/10.1155/2020/5945718.
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Coupling supercritical carbon dioxide (S-CO2) Brayton cycle with Gen-IV reactor concepts could bring advantages of high compactness and efficiency. This study aims to design proper simple and recompression S-CO2 Brayton cycles working as the indirect cooling system for a mediate-temperature lead fast reactor and quantify the Brayton cycle performance with different heat rejection temperatures (from 32°C to 55°C) to investigate its potential use in different scenarios, like arid desert areas or areas with abundant water supply. High-efficiency S-CO2 Brayton cycle could offset the power conversion efficiency decrease caused by low core outlet temperature (which is 480°C in this study) and high compressor inlet temperature (which varies from 32°C to 55°C in this study). A thermodynamic analysis solver is developed to provide the analysis tool. The solver includes turbomachinery models for compressor and turbine and heat exchanger models for recuperator and precooler. The optimal design of simple Brayton cycle and recompression Brayton cycle for the lead fast reactor under water-cooled and dry-cooled conditions are carried out with consideration of recuperator temperature difference constraints and cycle efficiency. Optimal cycle efficiencies of 40.48% and 35.9% can be achieved for the recompression Brayton cycle and simple Brayton cycle under water-cooled condition. Optimal cycle efficiencies of 34.36% and 32.6% can be achieved for the recompression Brayton cycle and simple Brayton cycle under dry-cooled condition (compressor inlet temperature equals to 55°C). Increasing the dry cooling flow rate will be helpful to decrease the compressor inlet temperature. Every 5°C decrease in the compressor inlet temperature will bring 1.2% cycle efficiency increase for the recompression Brayton cycle and 0.7% cycle efficiency increase for the simple Brayton cycle. Helpful conclusions and advises are proposed for designing the Brayton cycle for mediate-temperature nuclear applications in this paper.
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Choi, Sungwook, In Woo Son, and Jeong Ik Lee. "Comparative Performance Evaluation of Gas Brayton Cycle for Micro–Nuclear Reactors." Energies 16, no. 4 (February 20, 2023): 2065. http://dx.doi.org/10.3390/en16042065.
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Gas Brayton cycles have been considered the next promising power cycles for microreactors. Especially the open-air and closed supercritical CO2 (S-CO2) Brayton cycles have received attention due to their high thermal efficiency and compact component sizes when compared to the steam Rankine cycle. In this research, the performances of the open-air and closed S-CO2 Brayton cycle at microreactor power range are compared with polytropic turbomachinery efficiency. When optimizing the cycle, three different optimization parameters are considered in this paper: maximum efficiency, maximum cycle specific work, and maximum of the product of both indicators. For the air Brayton cycle, the maximum of the product of both indicators allows to consider both efficiency and specific work while optimizing the cycle. However, for the S-CO2 Brayton cycle, the best performing conditions follow either maximum efficiency or the maximum cycle specific work conditions. In general, the S-CO2 power cycle should be designed and optimized to maximize the cycle specific work for commercial-scale application. The results show that the air Brayton cycle can achieve near 45% efficiency when it can couple with a microreactor with a core outlet temperature higher than 700 °C. However, the S-CO2 power cycle can still achieve above 30% efficiency when it is coupled with a microreactor with a core outlet temperature higher than 500 °C, whereas the air Brayton cycle cannot even reach breakeven condition.
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Siddiqui, Muhammad Ehtisham, and Khalid H. Almitani. "Proposal and Thermodynamic Assessment of S-CO2 Brayton Cycle Layout for Improved Heat Recovery." Entropy 22, no. 3 (March 6, 2020): 305. http://dx.doi.org/10.3390/e22030305.
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This article deals with the thermodynamic assessment of supercritical carbon dioxide (S-CO2) Brayton power cycles. The main advantage of S-CO2 cycles is the capability of achieving higher efficiencies at significantly lower temperatures in comparison to conventional steam Rankine cycles. In the past decade, variety of configurations and layouts of S-CO2 cycles have been investigated targeting efficiency improvement. In this paper, four different layouts have been studied (with and without reheat): Simple Brayton cycle, Recompression Brayton cycle, Recompression Brayton cycle with partial cooling and the proposed layout called Recompression Brayton cycle with partial cooling and improved heat recovery (RBC-PC-IHR). Energetic and exergetic performances of all configurations were analyzed. Simple configuration is the least efficient due to poor heat recovery mechanism. RBC-PC-IHR layout achieved the best thermal performance in both reheat and no reheat configurations ( η t h = 59.7% with reheat and η t h = 58.2 without reheat at 850 °C), which was due to better heat recovery in comparison to other layouts. The detailed component-wise exergy analysis shows that the turbines and compressors have minimal contribution towards exergy destruction in comparison to what is lost by heat exchangers and heat source.
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Woodward, John B. "Ideal Cycle Evaluation of Steam Augmented Gas Turbines." Journal of Ship Research 40, no. 01 (March 1, 1996): 79–88. http://dx.doi.org/10.5957/jsr.1996.40.1.79.
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A wide range of air-standard Brayton and modified-Brayton power cycles are evaluated to determine their second-law efficiencies and their volume flows per unit output. A cycle with reheating is chosen for further analysis on the basis of its potential for high efficiency through exploitation of its exhaust availability (exergy) and its low volume rates. This exploitation can be had either through a conventional Rankine bottoming cycle, or through injection of the bottoming cycle steam into the Brayton turbine. The Rankine bottoming cycle is superior with respect to second-law efficiency; the cycle augmented by injected steam is superior with respect to volume flows. Examination of irreversibilities illuminates the reasons for the better efficiency of the Rankine bottoming cycle alternative.
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Li, Kai, and Kai Sun. "Influence of Supercritical Carbon Dioxide Brayton Cycle Parameters on Intelligent Circulation System and Its Optimization Strategy." Journal of Physics: Conference Series 2066, no. 1 (November 1, 2021): 012074. http://dx.doi.org/10.1088/1742-6596/2066/1/012074.
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Abstract The supercritical carbon dioxide (SCO2) Brayton cycle takes advantage of the special physical properties of carbon dioxide near the critical point (31.1 °C, 7.39MPa), and has higher energy conversion efficiency than the current large-scale steam power cycle. This cycle can be widely used in the field of power generation, but a lot of research work is still needed in terms of component parameters and layout under different working conditions. In this regard, the purpose of this paper is to study the influence of supercritical carbon dioxide Brayton cycle parameters on cycle efficiency and its optimization strategy. Based on the first law of thermodynamics, this paper uses Aspen Plus software to establish S-CO2 Brayton cycle system models with different circulation arrangements. In this paper, the existing algorithm of the simulation system and the newly-built algorithm are used to build the S-CO2 shunt and recompression Brayton cycle system model, and the accuracy of the model is verified with experimental data from literature. Then this paper conducts disturbance experiments on the model to study the influence of heater heating, valve opening and precooler cooling on the system, and analyze the dynamic characteristics of the system. Experimental results show that the thermal efficiency of the simple Brayton cycle is much lower than that of the recompression Brayton cycle and the split recompression Brayton cycle under higher parameters. The compressor outlet pressure and the turbine inlet temperature have an effect on the efficiency of the recompression Brayton cycle. The impact is significant, and the optimal value of the compressor shunt coefficient is between 0.5-0.7, which provides a reference for the layout optimization method of the SCO2 Brayton cycle and the optimization of the same type of power generation cycle.
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Santos, J. T. dos, T. M. Fagundes, E. D. dos Santos, L. A. Isoldi, and L. A. O. Rocha. "ANALYSIS OF A COMBINED BRAYTON/RANKINE CYCLE WITH TWO REGENERATORS IN PARALLEL." Revista de Engenharia Térmica 16, no. 2 (December 31, 2017): 10. http://dx.doi.org/10.5380/reterm.v16i2.62205.
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This work presents a configuration of two regenerators in parallel for a power generation Brayton/Rankine cycle where the output power is 10 MW. The working fluids considered for the Brayton and Rankine cycles are air and water, respectively. The addition of a regenerator with the previous existing cycle of this kind resulted in the addition of a second-stage turbine in the Rankine cycle of reheat. The objective of this modification is to increase the thermal efficiency of the combined cycle. In order to examine the efficiency of the new configuration, it is performed a thermodynamic modelling and numerical simulations for both cases: a regular Brayton/Rankine cycle and the one with the proposed changes. At the end of the simulations, the two cycles are compared, and it is seen that the new configuration reaches a 0.9% higher efficiency. In addition, the vapor quality at the exit of the higher turbine is higher, reducing the required mass flow rate in 14%.
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Sun, Lei, Yuqi Wang, Ding Wang, and Yonghui Xie. "Parametrized Analysis and Multi-Objective Optimization of Supercritical CO2 (S-CO2) Power Cycles Coupled with Parabolic Trough Collectors." Applied Sciences 10, no. 9 (April 30, 2020): 3123. http://dx.doi.org/10.3390/app10093123.
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Supercritical CO2 (S-CO2) Brayton cycles have become an effective way in utilizing solar energy, considering their advantages. The presented research discusses a parametrized analysis and systematic comparison of three S-CO2 power cycles coupled with parabolic trough collectors. The effects of turbine inlet temperature and pressure, compressor inlet temperature, and pressure on specific work, overall efficiency, and cost of core equipment of different S-CO2 Brayton cycles are discussed. Then, the two performance criteria, including specific work and cost of core equipment, are compared, simultaneously, between different S-CO2 cycle layouts after gaining the Pareto sets from multi-objective optimizations using genetic algorithm. The results suggest that the simple recuperation cycle layout shows more excellent performance than the intercooling cycle layout and the recompression cycle layout in terms of cost, while the advantage in specific work of the intercooling cycle layout and the recompression cycle layout is not obvious. This study can be useful in selecting cycle layout using solar energy by the parabolic trough solar collector when there are requirements for the specific work and the cost of core equipment. Moreover, high turbine inlet temperature is recommended for the S-CO2 Brayton cycle using solar energy.
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Zhang, W., L. Chen, and F. Sun. "Power and efficiency optimization for combined Brayton and two parallel inverse Brayton cycles. Part 2: Performance optimization." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 3 (March 1, 2008): 405–13. http://dx.doi.org/10.1243/09544062jmes640b.
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The power and efficiency of the open combined Brayton and two parallel inverse Brayton cycles are analysed and optimized based on the model established using finite-time thermodynamics in Part 1 of the current paper by adjusting the compressor inlet pressure of the two parallel inverse Brayton cycles, the mass flowrate and the distribution of pressure losses along the flow path. It is shown that the power output has a maximum with respect to the compressor inlet pressures of the two parallel inverse Brayton cycles, the air mass flowrate or any of the overall pressure drops, and the maximized power output has an additional maximum with respect to the compressor pressure ratio of the top cycle. The power output and the thermal conversion efficiency have the maximum values when the mass flowrates of the first and the second inverse Brayton cycles are the same. When the optimization is performed with the constraints of a fixed fuel flowrate and the power plant size, the power output and thermal conversion efficiency can be maximized again by properly allocating the fixed overall flow area among the compressor inlet of the top cycle and the turbine outlets of the two parallel inverse Brayton cycles. The numerical examples show the effects of design parameters on the power output and heat conversion efficiency.
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Shaw, John E. "Comparing Carnot, Stirling, Otto, Brayton and Diesel Cycles." Transactions of the Missouri Academy of Science 42, no. 2008 (January 1, 2008): 1–6. http://dx.doi.org/10.30956/0544-540x-42.2008.1.
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Comparing the efficiencies of the Carnot, Stirling, Otto, Brayton and Diesel cycles can be a frustrating experience for the student. The efficiency of Carnot and Stirling cycles depends only on the ratio of the temperature extremes whereas the efficiency of Otto and Brayton cycles depends only on the compression ratio. The efficiency of a Diesel cycle is generally expressed in terms of the temperatures at the four turning points of the cycle or the volumes at these turning points. How does one actually compare the efficiencies of these thermodynamic cycles? To compare the cycles, an expression for the efficiency of the Diesel cycle will be obtained in terms of the compression ratio and the ratio of the temperature extremes of the cycle. It is found that for a fixed temperature ratio that the efficiency increases with compression ratio for the Otto, Brayton and Diesel cycles until their efficiency is the same as that of the corresponding Carnot cycle. This occurs at the point where the heat input to the cycles is zero. For a fixed compression ratio the efficiency increases with temperature ratio for the Carnot and Stirling cycles but decreases for the Diesel cycle. This is an important factor in understanding how a Diesel cycle can be made to be more efficient than an Otto cycle.
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Luo, Lihuang, Hong Gao, Chao Liu, and Xiaoxiao Xu. "Parametric Investigation and Thermoeconomic Optimization of a Combined Cycle for Recovering the Waste Heat from Nuclear Closed Brayton Cycle." Science and Technology of Nuclear Installations 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/6790576.
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A combined cycle that combines AWM cycle with a nuclear closed Brayton cycle is proposed to recover the waste heat rejected from the precooler of a nuclear closed Brayton cycle in this paper. The detailed thermodynamic and economic analyses are carried out for the combined cycle. The effects of several important parameters, such as the absorber pressure, the turbine inlet pressure, the turbine inlet temperature, the ammonia mass fraction, and the ambient temperature, are investigated. The combined cycle performance is also optimized based on a multiobjective function. Compared with the closed Brayton cycle, the optimized power output and overall efficiency of the combined cycle are higher by 2.41% and 2.43%, respectively. The optimized LEC of the combined cycle is 0.73% lower than that of the closed Brayton cycle.
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He, Yichuan, Aihua Dong, Min Xie, and Yang Liu. "A Design of Parameters with Supercritical Carbon Dioxide Brayton Cycle for CiADS." Science and Technology of Nuclear Installations 2018 (June 10, 2018): 1–9. http://dx.doi.org/10.1155/2018/3245604.
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Recompression supercritical carbon dioxide (SCO2) Brayton Cycle for the Chinese Initiative Accelerator Driven System (CiADS) is taken into account, and flexible thermodynamic modeling method is presented. The influences of the key parameters on thermodynamic properties of SCO2 Brayton Cycle are discussed and the comparative analyses on genetic algorithm and pattern search algorithm are conducted. It is shown that the cycle parameters such as turbine inlet temperature, pressure ratio, outlet temperature at the hot end of condenser, and terminal temperature difference of regenerator 1 and regenerator 2 have significant effects on the cycle thermal efficiency. The calculation results indicate that pattern search algorithm has better optimization performance and quicker calculating speed than genetic algorithm. The result of optimization of the parameters for CiADS with supercritical carbon dioxide Brayton Cycle is 35.97%. Compared with other nuclear power plants of SCO2 Brayton Cycle, CiADS with SCO2 Brayton Cycle does not have the best thermal efficiency, but the thermal efficiency can be improved with the reactor outlet temperature increases.
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Massardo, Aristide. "High-Efficiency Solar Dynamic Space Power Generation System." Journal of Solar Energy Engineering 113, no. 3 (August 1, 1991): 131–37. http://dx.doi.org/10.1115/1.2930484.
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Space power technologies have undergone significant advances over the past few years, and great emphasis is being placed on the development of dynamic power systems at this time. A design study has been conducted to evaluate the applicability of a combined cycle concept—closed Brayton cycle and organic Rankine cycle coupling—for solar dynamic space power generation systems. In the concept presented here (solar dynamic combined cycle), the waste heat rejected by the closed Brayton cycle working fluid is utilized to heat the organic working fluid of an organic Rankine cycle system. This allows the solar dynamic combined cycle efficiency to be increased compared to the efficiencies of two subsystems (closed Brayton cycle and organic fluid cycle). Also, for small-size space power systems (up to 50 kW), the efficiency of the solar dynamic combined cycle can be comparable with Stirling engine performance. The closed Brayton cycle and organic Rankine cycle designs are based on a great deal of maturity assessed in much previous work on terrestrial and solar dynamic power systems. This is not yet true for the Stirling cycles. The purpose of this paper is to analyze the performance of the new space power generation system (solar dynamic combined cycle). The significant benefits of the solar dynamic combined cycle concept such as efficiency increase, mass reduction, specific area—collector and radiator—reduction, are presented and discussed for a low earth orbit space station application.
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Ziółkowski, Paweł, Witold Zakrzewski, Oktawia Kaczmarczyk, and Janusz Badur. "Thermodynamic analysis of the double Brayton cycle with the use of oxy combustion and capture of CO2." Archives of Thermodynamics 34, no. 2 (June 1, 2013): 23–38. http://dx.doi.org/10.2478/aoter-2013-0008.
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Abstract In this paper, thermodynamic analysis of a proposed innovative double Brayton cycle with the use of oxy combustion and capture of CO2, is presented. For that purpose, the computation flow mechanics (CFM) approach has been developed. The double Brayton cycle (DBC) consists of primary Brayton and secondary inverse Brayton cycle. Inversion means that the role of the compressor and the gas turbine is changed and firstly we have expansion before compression. Additionally, the workingfluid in the DBC with the use of oxy combustion and CO2 capture contains a great amount of H2O and CO2, and the condensation process of steam (H2O) overlaps in negative pressure conditions. The analysis has been done for variants values of the compression ratio, which determines the lowest pressure in the double Brayton cycle.
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Zhang, Y., and J. Chen. "The Thermodynamic Performance Analysis of an Irreversible Space Solar Dynamic Power Brayton System and its Parametric Optimum Design." Journal of Solar Energy Engineering 128, no. 3 (February 24, 2006): 409–13. http://dx.doi.org/10.1115/1.2212440.
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A solar dynamic (SD) power system composed of a concentrating solar collector and an irreversible Brayton cycle system is set up, where the heat losses of the collector are dominated by the radiation, the heat transfer between the collector and the Brayton cycle system obeys Newton’s law, and the heat transfer between the Brayton cycle system and the ambient obeys the radiant heat transfer law. The cycle model is used to investigate synthetically the influence of the radiant heat losses of the collector, the finite-rate heat transfer, and the irreversible adiabatic processes in the Brayton cycle system on the performance of a space SD power Brayton system. The overall efficiency of the system and the other performance parameters are optimized. The optimal values of the important parameters and their corresponding upper or lower bounds are determined. Finally, the optimal performance of an endoreversible SD power Carnot system is simply derived.
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Chen, L., W. Zhang, and F. Sun. "Parametric analysis of a gas turbine cycle coupled to a Brayton refrigeration cycle." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 223, no. 5 (May 14, 2009): 497–503. http://dx.doi.org/10.1243/09576509jpe722.
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Performance analysis and optimization of an endoreversible Brayton cycle coupled to a Brayton refrigeration cycle has been performed using finite-time thermodynamics. The analy-tical formulae are derived with respect to power, efficiency, optimal extracted pressure ratio of air refrigeration cycle corresponding to optimal power, optimal power and the corresponding efficiency. The influences of various parameters on the cycle performances are analysed by numerical examples. The results show that there exists one optimal pressure ratio of the compressor corresponding to maximum power and another optimal pressure ratio of the compressor corresponding to maximum efficiency; the compressor inlet temperature is reduced by mixing the chilled working fluid from the Brayton refrigeration cycle and the main intake working fluid streams; the intake working fluid temperature could be controlled even below the temperature of the heat sink and the gas turbine performance can be improved.
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Mossi Idrissa, A. K., and K. Goni Boulama. "Advanced exergy analysis of a combined Brayton/Brayton power cycle." Energy 166 (January 2019): 724–37. http://dx.doi.org/10.1016/j.energy.2018.10.117.
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Baglivo, Cristina, Paolo Maria Congedo, and Pasquale Antonio Donno. "Analysis of Thermodynamic Cycles of Heat Pumps and Magnetic Refrigerators Using Mathematical Models." Energies 14, no. 4 (February 9, 2021): 909. http://dx.doi.org/10.3390/en14040909.
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This paper proposes a critical review of the different aspects concerning magnetic refrigeration systems, and performs a detailed analysis of thermodynamic cycles, using mathematical models found in the literature. Langevin’s statistical mechanical theory faithfully describes the physical operation of a refrigeration machine working according to a magnetic Ericsson cycle. Results of mathematical and real experimental models are compared to deduce which best describes the Ericsson cycle. The theoretical data are not perfectly consistent with the experimental data; there is a maximum deviation of about 30%. Numerical and experimental data confirm that very high Coefficient of Performance (COP) values of more than 20 can be achieved. The analysis of the Brayton cycle consisted of finding the mathematical model that considers the irreversibility of these machines. Starting from the thermodynamic properties of magnetocaloric materials based on statistical mechanics, the efficiency of an irreversible Brayton regenerative magnetic refrigeration cycle is studied. Considering the irreversibility in adiabatic transformations, the lower limit of the optimal ratio of two magnetic fields is determined, obtaining a valid optimization criterion for these machines operating according to a Brayton cycle. The results show that the Ericsson cycle achieves a higher Coefficient of Performance than the Brayton cycle, which has a higher cooling capacity as it operates with a larger temperature difference between the magnetocaloric material and source.
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Zhu, Dengting, Yun Lin, and Xinqian Zheng. "Strategy on performance improvement of inverse Brayton cycle system for energy recovery in turbocharged diesel engines." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 1 (May 9, 2019): 85–95. http://dx.doi.org/10.1177/0957650919847920.
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The inverse Brayton cycle is a potential technology for waste heat energy recovery. It consists of three components: one turbine, one heat exchanger, and one compressor. The exhaust gas is further expanded to subatmospheric pressure in the turbine, and then cooled in the heat exchanger, last compressed in the compressor into the atmosphere. The process above is the reverse of the pressurized Brayton cycle. This work has presented the strategy on performance improvement of the inverse Brayton cycle system for energy recovery in turbocharged diesel engines, which has pointed the way to the future development of the inverse Brayton cycle system. In the paper, an experiment was presented to validate the numerical model of a 2.0 l turbocharged diesel engine. Meanwhile, the influence laws of the inverse Brayton cycle system critical parameters, including turbocharger speed and efficiencies, and heat exchanger efficiency, on the system performance improvement for energy recovery are explored at various engine operations. The results have shown that the engine exhaust energy recovery efficiency increases with the engine speed up, and it has a maximum increment of 6.1% at the engine speed of 4000 r/min (the engine rated power point) and the full load. At the moment, the absolute pressure was before final compression is 51.9 kPa. For the inverse Brayton cycle system development in the future, it is essential to choose a more effective heat exchanger. Moreover, variable geometry turbines are very appropriate to achieve a proper matching between the turbocharging system and the inverse Brayton cycle system.
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Chen, L., W. Zhang, and F. Sun. "Power and efficiency optimization for combined Brayton and two parallel inverse Brayton cycles. Part 1: Description and modelling." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 3 (March 1, 2008): 393–403. http://dx.doi.org/10.1243/09544062jmes640a.
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A thermodynamic model for open combined Brayton and two parallel inverse Brayton cycles is established using finite-time thermodynamics in part A of the current paper. The flow processes of the working fluid with the pressure drops of the working fluid and the size constraints of the real power plant are modelled. There are 17 flow resistances encountered by the gas stream for the combined Brayton and two parallel inverse Brayton cycles. Six of these, the friction through the blades and vanes of the compressors and the turbines, are related to the isentropic efficiencies. The remaining flow resistances are always present because of the changes in flow cross-section at the compressor inlet of the top cycle, combustion inlet and outlet, turbine outlet of the top cycle, turbine outlets of the bottom cycle, heat exchanger inlets, and compressor inlets of the bottom cycle. These resistances control the air flowrate and the net power output. The relative pressure drops associated with the flow through various cross-sectional areas are derived as functions of the compressor inlet relative pressure drop of the top cycle. The analytical formulae about the relations between power output, thermal conversion efficiency, and the compressor pressure ratio of the top cycle are derived with the 17 pressure drop losses in the intake, compression, combustion, expansion, and flow process in the piping, the heat transfer loss to ambient, the irreversible compression and expansion losses in the compressors and the turbines, and the irreversible combustion loss in the combustion chamber. The performance of the model cycle is optimized by adjusting the compressor inlet pressure of the bottom cycles, the mass flowrate and the distribution of pressure losses along the flow path in part B of the current paper.
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Skokov, Konstantin, Alexey Karpenkov, Yury G. Pastushenkov, and Oliver Gutfleisch. "Numerical Simulation of Magnetic Cooling Cycles." Solid State Phenomena 190 (June 2012): 319–22. http://dx.doi.org/10.4028/www.scientific.net/ssp.190.319.
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A model for Brayton cooling cycles used in magnetic refrigeration near room temperature was developed. This model was used to calculate a theoretical limit of temperature span and cooling power. The cooling power was calculated for single and double Brayton cooling cycles with Gd as the working body. The obtained results clearly demonstrate the functional ranges of Bryton-cycle refrigerators.
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Beans, E. W. "Comparative Thermodynamics for Brayton and Rankine Cycles." Journal of Engineering for Gas Turbines and Power 112, no. 1 (January 1, 1990): 94–99. http://dx.doi.org/10.1115/1.2906483.
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The thermal efficiency, work per unit mass, and work per unit volume of the simple Rankine and Brayton cycles are expressed in terms of seven independent variables using a simplified thermodynamic model. By requiring equal efficiency, equal work conditions, and the same maximum cycle temperature for both cycles, two necessary relationships are established between the seven independent variables. These two relationships along with two maximum work conditions produce a method for comparing required and selected properties. These comparisons provide useful guidelines for the selection of the cycle and cycle fluids. The comparison analysis shows that for a given application the more attractive cycle is strongly dependent upon the fluids selected.
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Jarungthammachote, Sompop. "Thermodynamic investigation of intercooling location effect on supercritical CO2 recompression Brayton cycle." Journal of Mechanical Engineering and Sciences 15, no. 3 (September 19, 2021): 8262–76. http://dx.doi.org/10.15282/jmes.15.3.2021.05.0649.
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In S-CO2 recompression Brayton cycle, use of intercooling is a way to improve the cycle efficiency. However, it may decrease the efficiency due to increase of heat rejection. In this work, two S-CO2 recompression Brayton cycles are investigated using the thermodynamic model. The first cycle has intercoolings in a main compression and a recompression process (MCRCIC) and the second cycle has an intercooling in only the recompression process (RCIC). The thermal efficiencies of both cycles are compared with that of S-CO2 recompression Brayton cycle with intercooling in the main compression process (MCIC). Effects of a split fraction (SF) and a ratio of pressure ratio of the recompression (RPRRC) on the thermal efficiencies of MCRCIC and RCIC are also studied. The study results show that the intercooling of recompressor in MCRCIC and RCIC can reduce the compression power. However, it also rejects heat from the cycle and this leads to increasing added heat in the heater. The thermal efficiency of MCRCIC and RCIC are, then, lower than that of the MCIC. For the effects of RPRRC and SF to the thermal efficiency of the cycles, in general, when RPRRC increases, the thermal efficiency decreases due to increasing rejected heat. The increase in SF causes increasing thermal efficiency of the cycles and the thermal efficiency, then, decrease when SF is beyond the optimal value.
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Liu, Tianye, Jingze Yang, Zhen Yang, and Yuanyuan Duan. "Thermo-economic optimization of supercritical CO2 Brayton cycle on the design point for application in solar power tower system." E3S Web of Conferences 242 (2021): 01002. http://dx.doi.org/10.1051/e3sconf/202124201002.
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The supercritical CO2 Brayton cycle integrated with a solar power tower system has the advantages of high efficiency, compact cycle structure, strong scalability, and great power generation potential, which can positively deal with the energy crisis and global warming. The selection and optimization of design points are very important for actual operating situations. In this paper, the thermodynamic and economic models of the 10 MWe supercritical CO2 Brayton cycle for application in solar power tower system are established. Multi-objective optimizations of the simple recuperative cycle, reheating cycle, and recompression cycle at different compressor inlet temperature are completed. The thermal efficiency and the levelized energy cost are selected as the fitness functions. The ranges of the optimal compressor inlet pressure and reheating pressure on the Pareto frontier are analyzed. Finally, multiobjective optimizations and analysis of the supercritical CO2 Brayton cycle at different ambient temperature are carried out. This paper investigates the influence of the compressor inlet temperature and ambient temperature on the thermal efficiency and economic performance of the supercritical CO2 Brayton cycle.
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Wu, C., and R. L. Kiang. "Power Performance of a Nonisentropic Brayton Cycle." Journal of Engineering for Gas Turbines and Power 113, no. 4 (October 1, 1991): 501–4. http://dx.doi.org/10.1115/1.2906268.
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Work and power optimization of a Brayton cycle are analyzed with a finite-time heat transfer analysis. This work extends the recent flurry of publications in heat engine efficiency under the maximum power condition by incorporating nonisentropic compression and expansion. As expected, these nonisentropic processes lower the power output as well as the cycle efficiency when compared with an endoreversible Brayton cycle under the same conditions.
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Malaver de la Fuente, Manuel. "La relación de trabajo de retroceso de un ciclo Brayton." Ingeniería, investigación y tecnología 11, no. 3 (July 1, 2010): 259–66. http://dx.doi.org/10.22201/fi.25940732e.2010.11n3.022.
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Frost, T. H., B. Agnew, and A. Anderson. "Optimizations for Brayton-Joule Gas Turbine Cycles." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 206, no. 4 (November 1992): 283–88. http://dx.doi.org/10.1243/pime_proc_1992_206_045_02.
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Traditionally, the simple Brayton–Joule cycle has been optimized for maximum output and for minimum compressor work with inter-cooling and maximum turbine work with reheat. To these Woods et al. (1) have added optimization for peak efficiency of the simple cycle with internal irreversibilities. The results now presented include both maximum output and peak efficiency for both regenerative and intercool/reheat cycles with internal irreversibilities. Two special cases, for a regenerative cycle and for a non-regenerative cycle with both reheat and intercooling, are identified where the conditions for maximum output and peak efficiency coincide.
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Fujii, S., K. Kaneko, K. Otani, and Y. Tsujikawa. "Mirror Gas Turbines: A Newly Proposed Method of Exhaust Heat Recovery." Journal of Engineering for Gas Turbines and Power 123, no. 3 (October 1, 2000): 481–86. http://dx.doi.org/10.1115/1.1366324.
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A new conceptual combination of Brayton and inverted Brayton cycles with a heat sink by intercooling, which is dubbed the mirror gas turbine, has been evaluated and proposed in this paper. Prior to such evaluations, a preliminary test on the inverted cycle without intercooling was made experimentally to confirm the actual operation. The conventional method of recuperation in gas turbines can be replaced by the mirror gas turbine with a low working temperature of about 450°C at heat exchanger. The combined cycle of Brayton/Rankine for electricity generation plant may be improved by our concept into a system with steam turbines completely removed and with still high thermal efficiency. Ultra-micro turbines will be possible, producing the output power less than 10 kW as well as thermal efficiency of 20 percent.
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Goodarzi, Mohsen, Mohsen Kiasat, and Ehsan Khalilidehkordi. "Performance analysis of a modified regenerative Brayton and inverse Brayton cycle." Energy 72 (August 2014): 35–43. http://dx.doi.org/10.1016/j.energy.2014.04.072.
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Chong Zhi Ken and Syamimi Saadon. "Analysis of Recuperation Supercritical Carbon Dioxide Cycle for Heat Recovery of an Aircraft Engine." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 96, no. 2 (July 23, 2022): 1–9. http://dx.doi.org/10.37934/arfmts.96.2.19.
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Reducing fuel consumption and maximizing thrust power are both critical factors for aircraft engine. Various technologies have been discovered and developed to achieve these goals. One of them is perhaps by integrating a waste heat recovery system to the engine. Therefore, this study will focus on waste heat recovery technology for aircraft engine, by applying a recuperation-supercritical carbon dioxide cycle in order to reduce jet engines’ fuel consumption and minimizing fuel expenses. The analysis will be conducted by modeling and simulation using Aspen Plus software. A quantitative analysis is done in order to compare the new modified recuperation cycle with the conventional basic Brayton- cycle in terms of their performance. The results stated that for both thermal efficiency and network done, recuperation- cycle performs much better with 42.46% of efficiency and network done at 2197.67 kW, than basic Brayton cycle at only 18.53 % of thermal efficiency and 2555.84 kW of network done. When integrating both cycles to aircraft engine, each of the cycle exhibits greater Thrust Specific Fuel Consumption (TSFC) savings, with up to 13.91 % and improved value of 1.7474 kg/s/kN for basic Brayton- cycle, and savings of 7.06 % and improved value of 1.8865 kg/s/kN for recuperation- cycle.
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Lin, Bihong, and Jincan Chen. "The Performance Analysis of a Quantum Brayton Refrigeration Cycle with an Ideal Bose Gas." Open Systems & Information Dynamics 10, no. 02 (June 2003): 147–57. http://dx.doi.org/10.1023/a:1024610206559.
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A Brayton refrigeration cycle using an ideal Bose gas as the working substance is simply referred to as a quantum Brayton refrigeration cycle, which consists of two constant-pressure and two adiabatic processes. The influence of quantum degeneracy on the performance of the cycle is investigated, based on the correction equation of state of an ideal Bose gas. The general expressions of the coefficient of performance, refrigeration load and work input of the cycle are calculated. The lowest temperature of the working substance and the minimum pressure ratio of the two constant-pressure processes for a quantum Brayton refrigeration cycle are determined. The variations of the relative refrigeration load with the temperature of the cooled space and the pressure of the low constant-pressure process are discussed for three special cases. Some curves related to the important performance parameters are given. The results obtained here are compared with those of a classical Brayton refrigeration cycle using an ideal gas as the working substance. Some significant conclusions are obtained.
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Patel, Raj C., Diego C. Bass, Ganza Prince Dukuze, Angelina Andrade, and Christopher S. Combs. "Analysis and Development of a Small-Scale Supercritical Carbon Dioxide (sCO2) Brayton Cycle." Energies 15, no. 10 (May 13, 2022): 3580. http://dx.doi.org/10.3390/en15103580.
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Carbon dioxide’s (CO2) ability to reach the supercritical phase (7.39 MPa and 304.15 K) with low thermal energy input is an advantageous feature in power generation design, allowing for the use of various heat sources in the cycle. A small-scale supercritical carbon dioxide (sCO2) power cycle operating on the principle of a closed-loop Brayton cycle is currently under construction at The University of Texas at San Antonio, to design and develop a small-scale indirect-fired sCO2 Brayton cycle, acquire validation data of the cycle’s performance, and compare the cycle’s performance to other cycles operating in similar conditions. The power cycle consists of four principal components: A reciprocating piston compressor, a heating source, a reciprocating piston expander to produce power, and a heat exchanger to dissipate excess heat. The work explained in the present manuscript describes the theory and analysis conducted to design the piston expander, heating source, and heat exchanger in the cycle. Theoretical calculations indicate that using sCO2 for the Brayton cycle generates 4.5 kW of power with the inlet pressure and temperature of 17.23 MPa and 358.15 K to the piston expander. Based on the fully isentropic conditions, the thermal efficiency of the system is estimated to be 12.75%.
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Chen, Lingen, Chenqi Tang, Huijun Feng, and Yanlin Ge. "Power, Efficiency, Power Density and Ecological Function Optimization for an Irreversible Modified Closed Variable-Temperature Reservoir Regenerative Brayton Cycle with One Isothermal Heating Process." Energies 13, no. 19 (October 2, 2020): 5133. http://dx.doi.org/10.3390/en13195133.
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One or more isothermal heating process was introduced to modify single and regenerative Brayton cycles by some scholars, which effectively improved the thermal efficiency and significantly reduced the emissions. To analyze and optimize the performance of this type of Brayton cycle, a regenerative modified Brayton cycle with an isothermal heating process is established in this paper based on finite time thermodynamics. The isothermal pressure drop ratio is variable. The irreversibilities of the compressor, turbine and all heat exchangers are considered in the cycle, and the heat reservoirs are variable-temperature ones. The function expressions of four performance indexes; that is, dimensionless power output, thermal efficiency, dimensionless power density and dimensionless ecological function are obtained. With the dimensionless power density as the optimization objective, the heat conductance distributions among all heat exchangers and the thermal capacitance rate matching among the working fluid and heat reservoir are optimized. Based on the NSGA-II algorithm, the cycle’s double-, triple- and quadruple-objective optimization are conducted with the total pressure ratio and the heat conductance distributions among heat exchangers as design variables. The optimal value is chosen from the Pareto frontier by applying the LINMAP, TOPSIS and Shannon entropy methods. The results show that when the pressure ratio in the compressor is less than 12.0, it is beneficial to add the regenerator to improve the cycle performance; when the pressure ratio is greater than 12.0, adding the regenerator will reduce the cycle performance. For single-objective optimization, the four performance indexes could be maximized under the optimal pressure ratios, respectively. When the pressure ratio is greater than 9.2, the cycle is simplified to a closed irreversible simple modified Brayton cycle with one isothermal heating process and coupled to variable-temperature heat reservoirs. Therefore, when the regenerator is used, the range of pressure ratio is limited, and a suitable pressure ratio should be selected. The triple objective (dimensionless power output, dimensionless power density and dimensionless ecological function) optimization’ deviation index gained by LINMAP or TOPSIS method is the smallest. The optimization results gained in this paper could offer some new pointers for the regenerative Brayton cycles’ optimal designs.
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Woodward, John B. "The Rankine Topping Cycle Revisited." Journal of Ship Research 36, no. 01 (March 1, 1992): 91–98. http://dx.doi.org/10.5957/jsr.1992.36.1.91.
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Cascaded thermodynamic machines are familiar in marine engineering, even if the word "cascade" is not common currency in that field. The author refers to the almost universal practice of exhausting the working fluid (air) of a diesel engine into a gas turbine (the turbocharger, usually), followed by exhausting of that working fluid into a heat exchanger that energizes the working fluid (water) of yet another turbine. If the same practice is to be described in terms of the respective power cycles, we would probably say that the cascade consists of a Rankine cycle topped by a Brayton cycle which is in turn topped by a diesel cycle. In similar fashion, recognized nomenclature might describe the diesel component as the "topping cycle," and the Rankine as the "bottoming cycle." The topping/bottoming nomenclature usually implies two different working fluids, so that the Brayton cycle might be described as a subpart of the topping cycle.
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Sun, Lei, Lin Tao, Yonghui xie, Yuanjian Dang, and Yongqing Wang. "Analysis and study on the thermodynamic performance of S-CO2 simple Brayton cycle." MATEC Web of Conferences 207 (2018): 04007. http://dx.doi.org/10.1051/matecconf/201820704007.
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The S-CO2 Brayton cycle system has many characteristics such as low cost and compact structure, and is one of the hotspots in the fields of waste heat utilization, new energy and so on. In this paper, a mathematical model of the S-CO2 simple Brayton cycle is constructed, and the cyclic characteristics are analysed. The relationship between the component parameters of the system and the calculation parameters of the cycle such as the cycle efficiency and the output net work are obtained under the design conditions. Meanwhile, calculation models of turbine and compressor under off-design conditions are established, and the characteristics of the whole cycle are analyzed. Thus, the characteristics of off-design conditions of the simple cycle are obtained. This study provides some reference for the related research of the S-CO2 Brayton cycle and the practical engineering application.
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Kotowicz, Janusz, Mateusz Brzęczek, Aleksandra Walewska, and Kamila Szykowska. "Methanol Production in the Brayton Cycle." Energies 15, no. 4 (February 17, 2022): 1480. http://dx.doi.org/10.3390/en15041480.
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This article presents the concept of renewable methanol production in the gas turbine cycle. As part of the work, an analysis was performed, including the impact of changing the parameters in the methanol reactor on the obtained values of power, yield and efficiency of the reactor, and chemical conversion. The aim of this research was to investigate the possibility of integrating the system for the production of renewable methanol and additional production of electricity in the system. The efficiency of the chemical conversion process and the efficiency of the methanol reactor increases with increasing pressure and decreasing temperature. The highest efficiency values, respectively η = 0.4388 and ηR = 0.3649, are obtained for parameters in the reactor equal to 160 °C and 14 MPa. The amount of heat exchanged in all exchangers reached the highest value for 14 MPa and 160 °C and amounted to Q˙ = 2.28 kW. Additionally, it has been calculated that if an additional exchanger is used before the expander (heating the medium to 560 °C), the expander’s power will cover the compressor’s electricity demand.
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Abd El-Maksoud, R. "Binary Brayton Cycle with Isothermal Concept." International Conference on Aerospace Sciences and Aviation Technology 15, AEROSPACE SCIENCES (May 1, 2013): 1–11. http://dx.doi.org/10.21608/asat.2013.22184.
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Irianto, Ignatius Djoko. "DESIGN AND ANALYSIS OF HELIUM BRAYTON CYCLE FOR ENERGY CONVERSION SYSTEM OF RGTT200K." JURNAL TEKNOLOGI REAKTOR NUKLIR TRI DASA MEGA 18, no. 2 (June 22, 2016): 75. http://dx.doi.org/10.17146/tdm.2016.18.2.2320.
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ABSTRACTDESIGN AND ANALYSIS OF HELIUM BRAYTON CYCLE FOR ENERGY CONVERSION SYSTEM OF RGTT200K. The helium Brayton cycle for the design of cogeneration energy conversion system for RGTT200K have been analyzed to obtain the higher thermal efficiency and energy utilization factor. The aim of this research is to analyze the potential of the helium Brayton cycle to be implemented in the design of cogeneration energy conversion system of RGTT200K. Three configuration models of cogeneration energy conversion systems have been investigated. In the first configuration model, an intermediate heat exchanger (IHX) is installed in series with the gas turbine, while in the second configuration model, IHX and gas turbines are installed in parallel. The third configuration model is similar to the first configuration, but with two compressors. Performance analysis of Brayton cycle used for cogeneration energy conversion system of RGTT200K has been done by simulating and calculating using CHEMCAD code. The simulation result shows that the three configuration models of cogeneration energy conversion system give the temperature of thermal energy in the secondary side of IHX more than 800 oC at the reactor coolant mass flow rate of 145 kg/s. Nevertheless, the performance parameters, which include thermal efficiency and energy utilization factor (EUF), are different for each configuration model. By comparing the performance parameter in the three configurations of helium Brayton cycle for cogeneration energy conversion systems RGTT200K, it is found that the energy conversion system with a first configuration has the highest thermal efficiency and energy utilization factor (EUF). Thermal efficiency and energy utilization factor for the first configuration of the reactor coolant mass flow rate of 145 kg/s are 35.82% and 80.63%.Keywords: Helium Brayton cycle, RGTT200K, Energy conversion system, EUF, Efficiency, ABSTRAKANALISIS DAN DESAIN SIKLUS BRAYTON HELIUM UNTUK SISTEM KONVERSI ENERGI RGTT200K. Telah dilakukan analisis siklus Brayton helium pada desain sistem konversi energi kogenerasi RGTT200K untuk memperoleh tingkat efisiensi termal dan faktor pemanfaatan energi yang tinggi. Tujuan penelitian ini adalah untuk menganalisis potensi siklus Brayton helium untuk diterapkan dalam desain sistem konversi energi kogenerasi RGTT200K. Tiga model konfigurasi desain sistem konversi energi kogenerasi telah dianalisis. Pada model konfigurasi pertama Intermediate Heat Exchanger (IHX) dipasang secara serial dengan turbin gas, sedangkan pada model konfigurasi kedua IHX dan turbin gas dipasang secara paralel. Model konfigurasi ketiga mirip dengan konfigurasi pertama, tetapi pada model konfigurasi ketiga dipasang dua kompresor. Analisis kinerja pada desain siklus Brayton untuk sistem konversi energi RGTT200K dilakukan dengan cara simulasi dan perhitungan kinerja sistem konversi energi menggunakan kode komputer CHEMCAD. Hasil simulasi menunjukkan bahwa ketiga model konfigurasi dapat memberikan energi termal pada sisi sekunder IHX dengan temperatur lebih dari 800 oC jika laju aliran massa pendingin reaktor 145 kg/s. Namun demikian, paremeter kinerja yang meliputi efisiensi thermal dan faktor pemanfaatan energi (EUF) berbeda untuk masing-masing model konfigurasi. Hasil perbandingan parameter kinerja pada ketiga model konfigurasi siklus Brayton helium untuk sistem konversi energi kogenerasi RGTT200K menunjukkan bahwa model konfigurasi sistem konversi energi kogenerasi yang pertama memiliki efisiensi termal dan faktor pemanfaatan energi (EUF) tertinggi. Nilai efisiensi termal dan faktor pemanfaatan energi untuk model konfigurasi pertama dengan laju aliran massa pendingin reaktor 145 kg/s adalah 35,82% dan 80,63%. Kata kunci: Siklus Brayton helium, RGTT200K, Sistem konversi energi, EUF, EfisiensiKeywords : Helium Brayton cycle, RGTT200K, Energy conversion system, EUF, Efficiency,
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Carril, José Carbia, Álvaro Baaliña Insua, Javier Romero Gómez, and Manuel Romero Gómez. "HTR-Based Power Plants’ Performance Analysis Applied on Conventional Combined Cycles." Science and Technology of Nuclear Installations 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/716572.
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In high temperature reactors including gas cooled fast reactors and gas turbine modular helium reactors (GT-MHR) specifically designed to operate as power plant heat sources, efficiency enhancement at effective cost under safe conditions can be achieved. Mentioned improvements concern the implementation of two cycle structures: (a), a stand alone Brayton operating with helium and a stand alone Rankine cycle (RC) with regeneration, operating with carbon dioxide at ultrasupercritical pressure as working fluid (WF), where condensation is carried out at quasicritical conditions, and (b), a combined cycle (CC), in which the topping closed Brayton cycle (CBC) operates with helium as WF, while the bottoming RC is operated with one of the following WFs: carbon dioxide, xenon, ethane, ammonia, or water. In both cases, an intermediate heat exchanger (IHE) is proposed to provide thermal energy to the closed Brayton or to the Rankine cycles. The results of the case study show that the thermal efficiency, through the use of a CC, is slightly improved (from 45.79% for BC and from 50.17% for RC to 53.63 for the proposed CC with He-H2O operating under safety standards).
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Rindt, Karin, František Hrdlička, and Václav Novotný. "Preliminary prospects of a Carnot-battery based on a supercritical CO2 Brayton cycle." Acta Polytechnica 61, no. 5 (October 31, 2021): 644–60. http://dx.doi.org/10.14311/ap.2021.61.0644.
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As a part of the change towards a higher usage of renewable energy sources, which naturally deliver the energy intermittently, the need for energy storage systems is increasing. For the compensation of the disturbance in power production due to inter-day to seasonal weather changes, a long-term energy storage is required. In the spectrum of storage systems, one out of a few geographically independent possibilities is the use of heat to store electricity, so-called Carnot-batteries. This paper presents a Pumped Thermal Energy Storage (PTES) system based on a recuperated and recompressed supercritical CO2 Brayton cycle. It is analysed if this configuration of a Brayton cycle, which is most advantageous for supercritical CO2 Brayton cycles, can be favourably integrated into a Carnot-battery and if a similar high efficiency can be achieved, despite the constraints caused by the integration. The modelled PTES operates at a pressure ratio of 3 with a low nominal pressure of 8 MPa, in a temperature range between 16 °C and 513 °C. The modelled system provides a round-trip efficiency of 38.9 % and was designed for a maximum of 3.5 MW electric power output. The research shows that an acceptable round-trip efficiency can be achieved with a recuperated and recompressed Brayton Cycle employing supercritical CO2 as the working fluid. However, a higher efficiency would be expected to justify the complexity of the configuration.
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Mossi Idrissa, A. K., and K. Goni Boulama. "Investigation of the performance of a combined Brayton/Brayton cycle with humidification." Energy 141 (December 2017): 492–505. http://dx.doi.org/10.1016/j.energy.2017.09.097.
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Wang, Jinping, Jun Wang, Peter D. Lund, and Hongxia Zhu. "Thermal Performance Analysis of a Direct-Heated Recompression Supercritical Carbon Dioxide Brayton Cycle Using Solar Concentrators." Energies 12, no. 22 (November 15, 2019): 4358. http://dx.doi.org/10.3390/en12224358.
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In this study, a direct recompression supercritical CO2 Brayton cycle, using parabolic trough solar concentrators (PTC), is developed and analyzed employing a new simulation model. The effects of variations in operating conditions and parameters on the performance of the s-CO2 Brayton cycle are investigated, also under varying weather conditions. The results indicate that the efficiency of the s-CO2 Brayton cycle is mainly affected by the compressor outlet pressure, turbine inlet temperature and cooling temperature: Increasing the turbine inlet pressure reduces the efficiency of the cycle and also requires changing the split fraction, where increasing the turbine inlet temperature increases the efficiency, but has a very small effect on the split fraction. At the critical cooling temperature point (31.25 °C), the cycle efficiency reaches a maximum value of 0.4, but drops after this point. In optimal conditions, a cycle efficiency well above 0.4 is possible. The maximum system efficiency with the PTCs remains slightly below this value as the performance of the whole system is also affected by the solar tracking method used, the season and the incidence angle of the solar beam radiation which directly affects the efficiency of the concentrator. The choice of the tracking mode causes major temporal variations in the output of the cycle, which emphasis the role of an integrated TES with the s-CO2 Brayton cycle to provide dispatchable power.
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Wu, Pan, Chuntian Gao, and Jianqiang Shan. "Development and Verification of a Transient Analysis Tool for Reactor System Using Supercritical CO2 Brayton Cycle as Power Conversion System." Science and Technology of Nuclear Installations 2018 (September 2, 2018): 1–14. http://dx.doi.org/10.1155/2018/6801736.
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Supercritical CO2 Brayton cycle is a good choice of thermal-to-electric energy conversion system, which owns a high cycle efficiency and a compact cycle configuration. It can be used in many power-generation applications, such as nuclear power, concentrated solar thermal, fossil fuel boilers, and shipboard propulsion system. Transient analysis code for Supercritical CO2 Brayton cycle is a necessity in the areas of transient analyses, control strategy study, and accident analyses. In this paper, a transient analysis code SCTRAN/CO2 is developed for Supercritical CO2 Brayton Loop based on a homogenous model. Heat conduction model, point neutron power model (which is developed for nuclear power application), turbomachinery model for gas turbine, compressor and shaft model, and PCHE type recuperator model are all included in this transient analysis code. The initial verifications were performed for components and constitutive models like heat transfer model, friction model, and compressor model. The verification of integrated system transient was also conducted through making comparison with experiment data of SCO2EP of KAIST. The comparison results show that SCTRAN/CO2 owns the ability to simulate transient process for S-CO2 Brayton cycle. SCTRAN/CO2 will become an important tool for further study of Supercritical CO2 Bryton cycle-based nuclear reactor concepts.
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Wang, Shugang, Shuangshuang Li, Shuang Jiang, and Xiaozhou Wu. "Analysis of the Air-Reversed Brayton Heat Pump with Different Layouts of Turbochargers for Space Heating." Buildings 12, no. 7 (June 21, 2022): 870. http://dx.doi.org/10.3390/buildings12070870.
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The air-reversed Brayton cycle produces charming, environmentally friendly effects by using air as its refrigerant and has potential energy efficiency in applications related to space heating and building heating. However, there exist several types of cycle that need to be discussed. In this paper, six types of air-reversed Brayton heat pump with a turbocharger, applicable under different heating conditions, are developed. The expressions of the heating coefficient of performance (COP) and the corresponding turbine pressure ratio are derived based on thermodynamic analysis. By using these expressions, the effects of turbine pressure ratio on the COP under different working conditions are theoretically analyzed, and the optimal COPs of different cycles under specific working conditions are determined. It is observed that Cycles A and C have the highest heating COPs, and there is an optimal pressure ratio for each cycle. The corresponding pressure ratio of the optimal COP is different, concentrated in the range of 1.5–1.9. When the pressure ratio reaches the optimal value, increasing the pressure ratio does not significantly improve the heating COP. Take Cycle F as an example: the maximum error between the calculated results and experimental observation is lower than 5.6%. These results will enable further study of the air-reversed Brayton heat pump with a turbocharger from a different perspective.
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Strumpf, Hal J., and Murray G. Coombs. "Solar Receiver Experiment for the Space Station Freedom Brayton Engine." Journal of Solar Energy Engineering 112, no. 1 (February 1, 1990): 12–18. http://dx.doi.org/10.1115/1.2930752.
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An experimental investigation has been conducted to develop fabrication procedures and acquire test data for a heat receiver assembly (HRA) in support of the design and development effort for the Brayton engine solar receiver for the NASA Space Station Freedom solar dynamic option. The HRA configuration is a cylindrical receiver lined with tubes; each tube is surrounded by phase change material (PCM). The Brayton cycle working fluid flows inside the tubes. The PCM surrounding the tubes, a eutectic mixture of LiF and CaF2, is contained in a series of sealed metallic containment canisters. During periods of sunlight, heat is transferred through the PCM to the Brayton cycle working fluid; during periods of eclipse, the PCM gives up its heat to the working fluid. A section of a full-size receiver tube was fabricated, assembled, and tested. Performance of the receiver tube qualitatively validates the expected receiver performance. Over 4500 cycles (of approximately 91-min duration) had been completed as of June 15, 1989.
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Kumar, Sachin. "Performance Optimization of Combined Cycle Power Plant Considering Various Operating Parameters." Journal of Mechanical Engineering 18, no. 1 (January 15, 2021): 21–38. http://dx.doi.org/10.24191/jmeche.v18i1.15161.
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Combined cycle power plants are popular in the thermal engineering field for their higher efficiency as compared to normal cycles such as Rankine and Brayton Cycle. But main disadvantages of the cycle are waste heat rejection and low work output. To overcome these difficulties a heat recovery system is used in the present work to recover waste heat of the Brayton cycle as a steam generator for the Rankine cycle in a combined Gas-Vapor cycle. In the present work, the effect of factors such as “compression ratio”, “inlet air temperature” and “turbine inlet temperature” on cycle efficiency was calculated. It was found that cycle efficiency increases with increase in these factors. It was found that the optimum value of compression ratio is 12-18 for maximum output of combined cycle. Whereas inlet air temperature has adverse effect on cycle efficiency so it should be kept lower while increase in turbine inlet temperature increases the cycle’s work output and hence efficiency. Optimum values of turbine inlet temperature were found in the range of 1600-1700 K
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Chen, Lingen, Huijun Feng, and Yanlin Ge. "Power and Efficiency Optimization for Open Combined Regenerative Brayton and Inverse Brayton Cycles with Regeneration before the Inverse Cycle." Entropy 22, no. 6 (June 17, 2020): 677. http://dx.doi.org/10.3390/e22060677.
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A theoretical model of an open combined cycle is researched in this paper. In this combined cycle, an inverse Brayton cycle is introduced into regenerative Brayton cycle by resorting to finite-time thermodynamics. The constraints of flow pressure drop and plant size are taken into account. Thirteen kinds of flow resistances in the cycle are calculated. On the one hand, four isentropic efficiencies are used to evaluate the friction losses in the blades and vanes. On the other hand, nine kinds of flow resistances are caused by the cross-section variances of flowing channels, which exist at the entrance of top cycle compressor (TCC), the entrance and exit of regenerator, the entrance and exit of combustion chamber, the exit of top cycle turbine, the exit of bottom cycle turbine, the entrance of heat exchanger, as well as the entrance of bottom cycle compressor (BCC). To analyze the thermodynamic indexes of power output, efficiency along with other coefficients, the analytical formulae of these indexes related to thirteen kinds of pressure drop losses are yielded. The thermodynamic performances are optimized by varying the cycle parameters. The numerical results reveal that the power output presents a maximal value when the air flow rate and entrance pressure of BCC change. In addition, the power output gets its double maximal value when the pressure ratio of TCC further changes. In the premise of constant flow rate of working fuel and invariant power plant size, the thermodynamic indexes can be optimized further when the flow areas of the components change. The effect of regenerator on thermal efficiency is further analyzed in detail. It is reported that better thermal efficiency can be procured by introducing the regenerator into the combined cycle in contrast with the counterpart without the regenerator as the cycle parameters change in the critical ranges.
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Yang, Xiaoping, and Zhuodi Cai. "Thermodynamic performance analysis of supercritical carbon dioxide Brayton cycle." Thermal Science, no. 00 (2020): 294. http://dx.doi.org/10.2298/tsci200314294y.
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S-CO2 (supercritical carbon dioxide) is used as working fluid for power system cycle. This paper presents thermodynamic performance analysis results on S-CO2 Brayton cycle. Based on the assumptions of the relevant initial parameters, the mathematical models of compressor, turbine, recuperator and heater are constructed, and the thermal efficiency of regenerative Brayton cycle and recompression Brayton cycle are calculated and analyzed. The results reveal that the efficiency of the recompression cycle is higher than that of the simple regenerative cycle. The effects of inlet temperature, inlet pressure of the main compressor and inlet temperature, inlet pressure of the turbine on the thermodynamic performance of the recompression cycle are studied, and the influencing mechanism is explained. The results show that the cycle efficiency decreases with the increase of the inlet temperature of the main compressor; there exists an optimum inlet pressure in the main compressor to maximize the cycle efficiency; and the cycle efficiency of the system increases with the increase of the inlet temperature and pressure of the turbine. When the inlet temperature of the turbine exceeds 600 ?, the thermal efficiency of the cycle can reach more than 50%.
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Zhang, Yue, Congjie Ou, Bihong Lin, and Jincan Chen. "The Regenerative Criteria of an Irreversible Brayton Heat Engine and its General Optimum Performance Characteristics." Journal of Energy Resources Technology 128, no. 3 (October 22, 2005): 216–22. http://dx.doi.org/10.1115/1.2213272.
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An irreversible cycle model of the Brayton heat engine is established, in which the irreversibilities resulting from the internal dissipation of the working substance in the adiabatic compression and expansion processes and the finite-rate heat transfer in the regenerative and constant-pressure processes are taken into account. The power output and efficiency of the cycle are expressed as functions of temperatures of the working substance and the heat sources, heat transfer coefficients, pressure ratio, regenerator effectiveness, and total heat transfer area including the heat transfer areas of the regenerator and other heat exchangers. The regenerative criteria are given. The power output is optimized for a given efficiency. The general optimal performance characteristics of the cycle are revealed. The optimal performance of the Brayton heat engines with and without regeneration is compared quantitatively. The advantages of using the regenerator are expounded. Some important parameters of an irreversible regenerative Brayton heat engine, such as the temperatures of the working substance at different states, pressure ratio, maximum value of the pressure ratio, regenerator effectiveness and ratios of the various heat transfer areas to the total heat transfer area of the cycle, are further optimized. The optimal relations between these parameters and the efficiency of the cycle are presented by a set of characteristic curves for some assumed compression and expansion efficiencies. The results obtained may be helpful to the comprehensive understanding of the optimal performance of the Brayton heat engines with and without regeneration and play a theoretical instructive role for the optimal design of a regenerative Brayton heat engine.
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Ibrahim, O. M., S. A. Klein, and J. W. Mitchell. "Optimum Heat Power Cycles for Specified Boundary Conditions." Journal of Engineering for Gas Turbines and Power 113, no. 4 (October 1, 1991): 514–21. http://dx.doi.org/10.1115/1.2906271.
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Optimization of the power output of Carnot and closed Brayton cycles is considered for both finite and infinite thermal capacitance rates of the external fluid streams. The method of Lagrange multipliers is used to solve for working fluid temperatures that yield maximum power. Analytical expressions for the maximum power and the cycle efficiency at maximum power are obtained. A comparison of the maximum power from the two cycles for the same boundary conditions, i.e., the same heat source/sink inlet temperatures, thermal capacitance rates, and heat exchanger conductances, shows that the Brayton cycle can produce more power than the Carnot cycle. This comparison illustrates that cycles exist that can produce more power than the Carnot cycle. The optimum heat power cycle, which will provide the upper limit of power obtained from any thermodynamic cycle for specified boundary conditions and heat exchanger conductances is considered. The optimum heat power cycle is identified by optimizing the sum of the power output from a sequence of Carnot cycles. The shape of the optimum heat power cycle, the power output, and corresponding efficiency are presented. The efficiency at maximum power of all cycles investigated in this study is found to be equal to (or well approximated by) η=1−TL,in/φTH,in where φ is a factor relating the entropy changes during heat rejection and heat addition.
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Chen, Lingen, Zelong Zhang, and Fengrui Sun. "Thermodynamic Modeling for Open Combined Regenerative Brayton and Inverse Brayton Cycles with Regeneration before the Inverse Cycle." Entropy 14, no. 1 (January 10, 2012): 58–73. http://dx.doi.org/10.3390/e14010058.
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