Design and Analysis of Key Instruments of Supercritical Carbon Dioxide Brayton Cycle in Future Nuclear Power Field

2017 ◽  
Author(s):  
Lin Yuansheng ◽  
Wu Jun ◽  
Ma Can ◽  
Dai Chunhui ◽  
Zhao Zhenxing ◽  
...  
Keyword(s):  
Power Systems ◽  
Nuclear Power ◽  
Simulation Models ◽  
Flow Path ◽  
Brayton Cycle ◽  
Three Dimension ◽  
Compression Process ◽  
Power Cycle ◽  
Turbine Impeller ◽  
Supercritical Carbon

The Brayton cycle with supercritical carbon (S-CO2) as working medium is one of the most promising new nuclear power systems. As the key device during the expansion and compression process in the Brayton power cycle, the turbine and compressor design and performance analysis is difficult for the strong nonlinear properties during the near critical region of S-CO2 medium. The design and analysis of the S-CO2 turbine and compressor is the key point for increasing the power device performance and operation security. As a result, this paper proposes a detail design and analysis method for turbine and compressor in the S-CO2 Brayton power cycle. The MW grade power cycle is used as the research project. The inlet and outlet parameters of the turbine and compressor are determined according to the power cycle scheme. Engineering thermodynamic principles combined with two-zone loss model are chosen to carry out the one-dimensional flow path design for the turbine and compressor respectively. Then the quasi-three dimension design of the flow path is accomplished by stream curvature method. The three dimensional geometry structure of the impeller is designed in detail. On this basis, numerical simulation models of the turbine and compressor are established to analysis the flow field and structural strength vibration in detail. Moreover, the simulation results show that the isentropic efficiency of the compressor impeller is 96.9%. The maximum total displacements of the compressor and turbine impeller are 0.12 mm and 0.106 mm respectively. The maximum von Mises equivalent stresses of the compressor and turbine impeller are 372 MPa and 320 MPa respectively. The impeller can meet the strength safty requiments for the maximum stress values are much less than the yield stress of the material.

scholarly journals Dry-Cooled Supercritical CO2 Power for Advanced Nuclear Reactors

2014 ◽  
Author(s):  
T. M. Conboy ◽  
M. D. Carlson ◽  
G. E. Rochau
Keyword(s):  
Power Systems ◽  
Nuclear Energy ◽  
Energy Systems ◽  
Air Cooling ◽  
Brayton Cycle ◽  
Heat Rejection ◽  
Ambient Temperatures ◽  
Power Cycle ◽  
Dry Air ◽  
Compressor Inlet

Currently, waste heat rejection from electrical power systems accounts for the largest fraction of water withdrawals from the US fresh water table. Siting of nuclear power plants is limited to areas with access to a large natural supply of fresh or sea water. Due to a rise in energy needs and increased concern over environmental impact, dry air cooling systems are poised to play a large role in the future energy economy. In practice, the implementation of dry air-cooled condensing systems at steam plants has proven to be capital-intensive and requires the power cycle to take a significant efficiency penalty. These shortcomings are fundamental to dry-air steam condensation, which must occur at a fixed temperature. Closed-cycle gas turbines are an alternative to the conventional steam Rankine plant that allow for much improved dry heat rejection compatibility. Recent research into advanced nuclear energy systems has identified the supercritical CO2 (s-CO2) Brayton cycle in particular as a viable candidate for many proposed reactor types. The s-CO2 Brayton cycle can maintain superior thermal efficiency over a wide range of ambient temperatures, making these power systems ideally suited for dry air cooling, even in warm climates. For an SFR operating at 550°C, thermal efficiency is calculated to be 43% with a 50°C compressor inlet temperature. This is achieved by raising CO2 compressor inlet pressure in response to rising ambient temperatures. Preliminary design studies have shown that s-CO2 power cycle hardware will be compact and therefore well-matched to near-term and advanced integral SMR designs. These advantages also extend to the cooling plant, where it is estimated that dry cooling towers for an SFR-coupled s-CO2 power cycle will be similar in cost and scale to the evaporative cooling tower for an LWR. The projected benefits of the s-CO2 power cycle coupled to dry air heat rejection may enable the long-awaited rise of next-generation nuclear energy systems, while re-drawing the map for siting of small and large nuclear energy systems.

The Role of Turbomachinery Performance in the Optimization of Supercritical Carbon Dioxide Power Systems

2019 ◽  
Author(s):  
Alessandro Romei ◽  
Paolo Gaetani ◽  
Andrea Giostri ◽  
Giacomo Persico
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Power Systems ◽  
Pressure Ratio ◽  
Plant Size ◽  
Cycle Performance ◽  
Small Contribution ◽  
Compression Process ◽  
Multiple Cycle ◽  
Supercritical Carbon

Abstract The successful penetration of supercritical carbon dioxide (sCO2) power systems in the energy market largely depends on the achievable turbomachinery performance. The present study illustrates a systematic framework where both the compressor and the turbine are designed via validated (within ±2% pts against experiments) mean-line tools and the related impact on cycle performance estimates is quantitatively and qualitatively assessed. A significant effort is devoted to the analysis of centrifugal compressor performance operating close to the critical point, where sharp thermodynamic property variations may make critical the compression process. The analysis is performed for different compressor sizes and pressure ratios, showing a comparatively small contribution of compressor-intake fluid conditions to the machine efficiency, which may achieve technological competitive values (82 ÷ 85%) for representative full-scale sizes. Two polynomial correlations for both turbomachinery efficiencies are devised as a function of proper similarity parameters accounting for machine sizes and loadings. Such correlations can be easily embedded in power cycle optimizations, which are usually carried out assuming constant-turbomachinery efficiency, thus ignoring the effects of plant size and cycle operating parameters. Efficiency correlations are finally exploited to perform several optimizations of a recompressed sCO2 cycle, by varying multiple cycle parameters (i.e. maximum and minimum temperature, pressure ratio and net power output). The results highlight that the replacement of constant-efficiency assumption with the proposed correlations leads to more accurate performance predictions (i.e. cycle efficiency can differ by more than 4% pts), showing in particular that an optimal pressure ratio exists in the range 2 ÷ 5 for all the investigated configurations.

A Study of Supercritical Carbon Dioxide Power Cycle for Concentrating Solar Power Applications Using an Isothermal Compressor

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Jin Young Heo ◽  
Jinsu Kwon ◽  
Jeong Ik Lee
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Thermal Efficiency ◽  
Solar Power ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Concentrating Solar Power ◽  
Power Cycle ◽  
Compressor Inlet ◽  
Supercritical Carbon

For the concentrating solar power (CSP) applications, the supercritical carbon dioxide (s-CO2) power cycle is beneficial in many aspects, including high cycle efficiencies, reduced component sizing, and potential for the dry cooling option. More research is involved in improving this technology to realize the s-CO2 cycle as a candidate to replace the conventional power conversion systems for CSP applications. In this study, an isothermal compressor, a turbomachine which undergoes the compression process at constant temperature to minimize compression work, is applied to the s-CO2 power cycle layout. To investigate the cycle performance changes of adopting the novel technology, a framework for defining the efficiency of the isothermal compressor is revised and suggested. This study demonstrates how the compression work for the isothermal compressor is reduced, up to 50%, compared to that of the conventional compressor under varying compressor inlet conditions. Furthermore, the simple recuperated and recompression Brayton cycle layouts using s-CO2 as a working fluid are evaluated for the CSP applications. Results show that for compressor inlet temperatures (CIT) near the critical point, the recompression Brayton cycle using an isothermal compressor has 0.2–1.0% point higher cycle thermal efficiency compared to its reference cycle. For higher CIT values, the recompression cycle using an isothermal compressor can perform above 50% in thermal efficiency for a wider range of CIT than the reference cycle. Adopting an isothermal compressor in the s-CO2 layout can imply larger heat exchange area for the compressor which requires further development.

Development of the Supercritical Carbon Dioxide Power Cycle Experimental Loop With a Turbo-Generator

2017 ◽  
Author(s):  
Junhyun Cho ◽  
Hyungki Shin ◽  
Jongjae Cho ◽  
Ho-Sang Ra ◽  
Chulwoo Roh ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
High Speed ◽  
Small Scale ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Turbo Generator ◽  
Test Loop ◽  
Class Test ◽  
Supercritical Carbon

KIER (Korea Institute of Energy Research) has developed three supercritical carbon dioxide power cycle test loops since 2013. After developing a 10 kWe-class simple un-recuperated Brayton cycle, a second sub-kWe small-scale experimental test loop was manufactured to investigate the characteristics of the supercritical carbon dioxide power cycle, for which a high speed radial type turbo-generator was also designed and manufactured. Using only one channel of the nozzle, the partial admission method was adopted to reduce the rotational speed of the rotor so that commercial oil-lubricated bearings can be used. This was the world’s first approach to the supercritical carbon dioxide turbo-generator. After several tests, operation of the turbine for power production of up to 670 W was successful. Finally, an 80 kWe-class dual Brayton cycle test loop was designed. Before completion of the full test loop, a 60 kWe axial type turbo-generator was first manufactured and our previous 10 kWe-class test loop was upgraded to drive this turbo-generator. Due to leakage flow through the mechanical seal, a make-up loop was also developed. After assembling all test loops, a cold-run test and a preliminary operation test were conducted. In this paper, the power generating operation results of the sub-kWe-class test loop and the construction of the tens of kWe-class test loop which drives an axial type turbo-generator are described.

An adaptive flow path regenerator used in supercritical carbon dioxide Brayton cycle

2018 ◽  
Vol 138 ◽  
pp. 513-522 ◽  
Author(s):  
Miao Ding ◽  
Jian Liu ◽  
Wen-Long Cheng ◽  
Wen-Xu Huang ◽  
Qi-Nie Liu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Flow Path ◽  
Brayton Cycle ◽  
Supercritical Carbon

Flexibility and Adaptability of Closed Brayton Cycles Associated With Low Power Level Space Nuclear Heat Sources

1990 ◽  
Author(s):  
Z. P. Tilliette ◽  
F. O. Carre ◽  
E. Proust
Keyword(s):  
Power Systems ◽  
Nuclear Power ◽  
Power Level ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Nuclear Heat ◽  
Wide Range ◽  
Technical Advances ◽  
Long Lifetime ◽  
Space Nuclear Power

A feature of the French preliminary studies of space nuclear power systems of about 20 kwe is the selection of the closed Brayton cycle as the conversion subsystem. As examples of future applications of turbogenerators in space, near or longer term U.S. and Soviet projects are mentioned, including technical advances expected in this field. Several nuclear reactors concepts can be proposed now or in the future. The need for a satisfactory adaptation between the heat source and the converter prompts to further investigate the Brayton cycle capability for that purpose. For instance, a long lifetime thermal spectrum reactor would require a relatively low inlet temperature for moderator thermal conditioning. Cycle configurations featuring one or two separate radiators and possible intercooling are presented. Such arrangements imply a main low temperature radiator made, for instance, of multiple, pivoting tubes. It is shown that the Brayton cycle can offer flexibility and adaptability for a wide range of space missions.

150 kwe Supercritical Closed Cycle System

1971 ◽  
Vol 93 (1) ◽  
pp. 70-80 ◽  
Author(s):  
John R. Hoffmann ◽  
Ernest G. Feher
Keyword(s):  
Power Systems ◽  
High Speed ◽  
Nuclear Power ◽  
Power Conversion ◽  
Heat Engine ◽  
Working Fluid ◽  
Closed Cycle ◽  
Power Cycle ◽  
Cycle System ◽  
Potential Applicability

This paper explores the potential applicability of the Supercritical (Feher) Thermodynamic Power Cycle to advanced ground nuclear power systems. The supercritical cycle is a closed cycle heat engine that operates entirely above the critical pressure of the working fluid. It is characterized by high thermal efficiency and compactness of the machinery. The cycle is highly regenerated and receives heat over a narrow temperature range. For the evaluation of the advantages of the power conversion concept, a 150-kwe power conversion module has been selected that employs a gas turbine driven high speed alternator, using carbon dioxide as the working fluid.

Selecting the Optimum Supercritical CO2 Cycle for Indirect-Fired Applications

2019 ◽  
Author(s):  
Brittany Tom ◽  
January Smith ◽  
Aaron M. McClung
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Co2 ◽  
Operating Conditions ◽  
Working Fluid ◽  
Performance Goals ◽  
Brayton Cycle ◽  
Power Cycle ◽  
And Performance ◽  
Supercritical Carbon

Abstract Existing research has demonstrated the viability of supercritical carbon dioxide as an efficient working fluid with numerous advantages over steam in power cycle applications. Selecting the appropriate power cycle configuration for a given application depends on expected operating conditions and performance goals. This paper presents a comparison for three indirect fired sCO2 cycles: recompression closed Brayton cycle, dual loop cascaded cycle, and partial condensation cycle. Each cycle was modeled in NPSS with an air side heater, given the same baseline assumptions and optimized over a range of conditions. Additionally, limitations on the heater system are discussed.

A Study of s-CO2 Power Cycle for CSP Applications Using an Isothermal Compressor

2017 ◽  
Author(s):  
Jin Young Heo ◽  
Yoonhan Ahn ◽  
Jeong Ik Lee
Keyword(s):  
Thermal Efficiency ◽  
Rankine Cycle ◽  
Cycle Performance ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Compression Process ◽  
Power Cycle ◽  
Compressor Inlet ◽  
Inlet Conditions ◽  
Recompression Cycle

For the concentrating solar power (CSP) applications, the supercritical carbon dioxide (s-CO2) power cycle is beneficial in many aspects, including higher cycle efficiencies, reduced component sizing, and potential for the dry cooling option, in comparison to the conventional steam Rankine cycle. Increasing number of investigations and research projects are involved in improving this technology to realize the s-CO2 cycle as a candidate to replace the conventional power conversion systems. In this conceptual study, an isothermal compressor, a turbomachine which undergoes the compression process at constant temperature to minimize compression work, is applied to the s-CO2 power cycle layout. To investigate the cycle performance changes of adopting the novel technology, a framework for defining the efficiency of the isothermal compressor is revised and suggested. This study demonstrates how the compression work for the isothermal compressor is reduced compared to that of the conventional compressor under varying compressor inlet conditions. Furthermore, the recompression Brayton cycle layout using s-CO2 as a working fluid is evaluated for the CSP applications. Results show that for compressor inlet temperatures (CIT) near the critical point, the simple recuperated Brayton cycle with an isothermal compressor performs better than the given reference recompression cycle by 6–10% points in terms of cycle thermal efficiency. For higher CIT values, the recompression cycle using an isothermal compressor can perform above 50% in thermal efficiency. Adopting an isothermal compressor in the s-CO2 layout, however, can imply larger heat exchange area for the compressor which requires further detailed design for realization in the future.

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