Parametric Investigation of Brayton Cycle for High Temperature Gas-Cooled Reactors

Volume 4 ◽  
2004 ◽  
Author(s):  
Chang H. Oh ◽  
Richard L. Moore
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Supercritical Carbon Dioxide ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Pebble Bed ◽  
Engineering Research ◽  
Cycle Efficiency ◽  
High Temperature Gas ◽  
Supercritical Carbon

The Idaho National Engineering and Environmental Laboratory (INEEL) has investigated a Brayton cycle efficiency improvement on a high temperature gas-cooled reactor (HTGR) as part of Generation-IV nuclear engineering research initiative. In this study, we are investigating helium Brayton cycles for the secondary side of an indirect energy conversion system. Ultimately we will investigate the improvement of the Brayton cycle using other fluids, such as supercritical carbon dioxide. Prior to the cycle improvement study, we established a number of baseline cases for the helium indirect Brayton cycle. The baseline cases are based on a 250 MW thermal pebble bed HTGR. In this study, we used the HYSYS computer code for optimization of the helium Brayton cycle and the balance of plant (BOP). In addition to the HYSYS process optimization, we performed parametric study to see the effect of important parameters on the cycle efficiency. For these parametric calculations, we also used a cycle efficiency model that was developed using the Visual Basic computer language. The results from this study are applicable to other reactor concepts such as a very high temperature gas-cooled reactor (VHTR), fast gas-cooled reactor (FGR), supercritical water reactor (SWR), and others. As part of this study we are currently investigated single-shaft vs. multiple shaft arrangement for cycle efficiency and comparison, which will be published in the next paper. The ultimate goal of this study is to use supercritical carbon dioxide for the HTGR power conversion loop in order to improve the cycle efficiency to values great than that of the helium Brayton cycle. This paper includes preliminary calculations of the steady state overall Brayton cycle efficiency based on the pebble bed reactor reference design (helium used as the working fluid) and compares those results with an initial calculation of a CO2 Brayton cycle.

Parametric Investigation of Supercritical Carbon Dioxide Brayton Cycle for High Temperature Gas-Cooled Reactor (HTGR)

2018 ◽  
Author(s):  
Gang Zhao ◽  
Ping Ye ◽  
Xiaoyong Yang ◽  
Jie Wang
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Supercritical Carbon Dioxide ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Pebble Bed ◽  
Split Flow ◽  
Under Construction ◽  
High Temperature Gas ◽  
Supercritical Carbon

High-temperature Gas-cooled Reactor Pebble-bed Module (HTR-PM) is under construction in Shidao Bay, Shandong of China. It is supposed to be the world’s first pebble-bed modular commercial demonstration plant for High Temperature Gas-cooled Reactor (HTGR). In HTR-PM project, water-Rankine cycles have been used in the power conversion system. Meanwhile, supercritical carbon dioxide (S-CO2) Brayton cycle has shown great potentials for future HTGR technology. Comparing with typical helium Brayton cycle, in S-CO2 cycle where critical properties of carbon dioxide are utilized, compressor work may reduce significantly and thermal efficiency may improve greatly. Furthermore, the general sizes of S-CO2 cycle equipment, such as heat exchanger and turbine, would be orders of magnitude smaller than water-Rankine system at similar power output. Therefore, parameters study of S-CO2 were conducted in this paper for future HTGR. Firstly, a physical model of S-CO2 Brayton cycles was built and the performance of cycles were analyzed. Secondly, compression ratio, temperature ratio, the inlet temperature of turbine, inlet parameters of compressor, and recuperated effectiveness were discussed as key cycle parameters. For heat capacities of CO2 are significantly different as a function of temperature and pressure, flow recompression was considered. Calculation was based on a split-flow cycle configuration. The split flow ratio was also analyzed. Finally, the parameters of S-CO2 cycle were optimized for HTGR. In conclusion, S-CO2 Brayton cycle will be a good option for future HTGR.

Primary Study on Carbon Dioxide Power Cycle of HTGR

2008 ◽  
Author(s):  
Chengjie Duan ◽  
Xiaoyong Yang ◽  
Jie Wang ◽  
Suyuan Yu
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Physical Properties ◽  
Critical Pressure ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Pressure Cycle ◽  
Cycle Efficiency ◽  
Thermal Physical Properties

At present, power cycles used in HTGR are indirect steam Rankine cycle and helium Brayton cycle. Using water or helium as working fluid which transform thermal energy into mechanical energy for HTGR power cycle has many disadvantages. Steam cycle could choose steam system which is similar to conventional coal-fired power plant, but because of the limit of material and equipments, there is big temperature difference between the steam and the helium, that makes big loss of thermal power and lowers the cycle efficiency. Helium can reach a high temperature in HTGR Brayton cycle and it has good stability, but because of helium has big isentropic exponent and low density, it is difficult to compress and makes helium turbine has shorter blades and more stages than normal gas turbine. Carbon dioxide has good thermal stability and physical properties. To avoid the reaction of CO2 with graphite and canning of fuel element at high temperature, it should be used in an indirect cycle as second loop working fluid. CO2 has appropriate critical pressure and temperature (7.38MPa, 304.19K) and can choose three types of cycle: supercritical cycle, subcritical-pressure cycle and trans-critical-pressure cycle (CO2 sometimes works under supercritical pressure, some times under subcritical-pressure). Carbon dioxide cycle works in a high pressure, so it makes pressure loss lower. When CO2 works close to its critical point, its density become larger than other conditions, and not change very much, this permits to reduce compress work. The thermal physical properties of carbon dioxide are totally different from helium due to CO2 works as real gas in the cycle. That causes the calculation of CO2 thermal physical properties, heat transfer and power cycle efficiency become difficult and need to be iterated. A systematic comparison between helium and carbon dioxide as working fluid for HTGR has been carried out. An empirical equation had been selected to estimate the thermal physical properties of carbon dioxide. Three types of carbon dioxide power cycle have been analyzed and the thermal efficiency has been calculated. A detailed introduction to the basic calculation process of the CO2 cycle thermal efficiency had been presented in the paper.

Modeling Off-Design and Part-Load Performance of Supercritical Carbon Dioxide Power Cycles

2013 ◽  
Author(s):  
John J. Dyreby ◽  
Sanford A. Klein ◽  
Gregory F. Nellis ◽  
Douglas T. Reindl
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Ambient Air ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Heat Rejection ◽  
Power Cycles ◽  
Part Load ◽  
Dry Cooling ◽  
Supercritical Carbon

Continuing efforts to increase the efficiency of utility-scale electricity generation has resulted in considerable interest in Brayton cycles operating with supercritical carbon dioxide (S-CO2). One of the advantages of S-CO2 Brayton cycles, compared to the more traditional steam Rankine cycle, is that equal or greater thermal efficiencies can be realized using significantly smaller turbomachinery. Another advantage is that heat rejection is not limited by the saturation temperature of the working fluid, facilitating dry cooling of the cycle (i.e., the use of ambient air as the sole heat rejection medium). While dry cooling is especially advantageous for power generation in arid climates, the reduction in water consumption at any location is of growing interest due to likely tighter environmental regulations being enacted in the future. Daily and seasonal weather variations coupled with electric load variations means the plant will operate away from its design point the majority of the year. Models capable of predicting the off-design and part-load performance of S-CO2 power cycles are necessary for evaluating cycle configurations and turbomachinery designs. This paper presents a flexible modeling methodology capable of predicting the steady state performance of various S-CO2 cycle configurations for both design and off-design ambient conditions, including part-load plant operation. The models assume supercritical CO2 as the working fluid for both a simple recuperated Brayton cycle and a more complex recompression Brayton cycle.

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.

Analysis of Advanced Supercritical Carbon Dioxide Power Cycles With a Bottoming Cycle for Concentrating Solar Power Applications

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Saeb M. Besarati ◽  
D. Yogi Goswami
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Solar Power ◽  
Waste Heat ◽  
Operating Conditions ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Concentrating Solar Power ◽  
Working Fluids ◽  
Supercritical Carbon

A number of studies have been performed to assess the potential of using supercritical carbon dioxide (S-CO2) in closed-loop Brayton cycles for power generation. Different configurations have been examined among which recompression and partial cooling configurations have been found very promising, especially for concentrating solar power (CSP) applications. It has been demonstrated that the S-CO2 Brayton cycle using these configurations is capable of achieving more than 50% efficiency at operating conditions that could be achieved in central receiver tower type CSP systems. Although this efficiency is high, it might be further improved by considering an appropriate bottoming cycle utilizing waste heat from the top S-CO2 Brayton cycle. The organic Rankine cycle (ORC) is one alternative proposed for this purpose; however, its performance is substantially affected by the selection of the working fluid. In this paper, a simple S-CO2 Brayton cycle, a recompression S-CO2 Brayton cycle, and a partial cooling S-CO2 Brayton cycle are first simulated and compared with the available data in the literature. Then, an ORC is added to each configuration for utilizing the waste heat. Different working fluids are examined for the bottoming cycles and the operating conditions are optimized. The combined cycle efficiencies and turbine expansion ratios are compared to find the appropriate working fluids for each configuration. It is also shown that combined recompression-ORC cycle achieves higher efficiency compared with other configurations.

Development of Turbine and Combustor for a Semi-Closed Recuperated Brayton Cycle of Supercritical Carbon Dioxide

2017 ◽  
Author(s):  
Takashi Sasaki ◽  
Masao Itoh ◽  
Hideyuki Maeda ◽  
Junichi Tominaga ◽  
Daizo Saito ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
New Technologies ◽  
Combined Cycle ◽  
Working Fluid ◽  
Brayton Cycle ◽  
The Usa ◽  
Demonstration Plant ◽  
Competitive Efficiency ◽  
Supercritical Carbon

Toshiba has been developing a turbine and a combustor for a semi-closed recuperated Brayton cycle of supercritical carbon dioxide called the Allam cycle, which is capable of both sequestrating 100% of carbon dioxide generated by combustion and providing electricity with competitive efficiency as the advanced combined cycle. The 25 MWe class demonstration plant with natural gas for this innovative cycle is being constructed in the USA by NET Power LLC and its operation is expected to be in 2017. Toshiba is going to provide the main components of its turbine and combustor. This paper describes the specification of the turbine and the combustor and consideration necessary to realize them in the first of a kind design condition of 30MPa with a supercritical carbon dioxide as its working fluid. This paper also describes some of the validation tests to realize new technologies before this turbine and combustor are installed and operated in the demonstration plant.

Off-Nominal Component Performance in a Supercritical Carbon Dioxide Brayton Cycle

2015 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Martha A. King
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Integrated System ◽  
Design System ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Wide Range ◽  
Primary Driver ◽  
Atomic Power Laboratory ◽  
Supercritical Carbon

Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon dioxide (S-CO2) Brayton system at the Bettis Atomic Power Laboratory. The Integrated System Test (IST) is a simple recuperated closed Brayton cycle with a variable-speed turbine-driven compressor and a constant-speed turbine-driven generator using S-CO2 as the working fluid designed to output 100 kWe. The main focus of the IST is to demonstrate operational, control, and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. Therefore, the IST was designed to operate in a configuration and at conditions that support demonstrating the controllability of the closed S-CO2 Brayton cycle. Operating at high system efficiency and meeting a specified efficiency target are not requirements of the IST. However, efficiency is a primary driver for many commercial applications of S-CO2 power cycles. This paper uses operational data to evaluate component off-nominal performance and predict that design system operation would be achievable.

Analysis of Advanced Supercritical Carbon Dioxide Power Cycles With a Bottoming Cycle for Concentrating Solar Power Applications

2013 ◽  
Author(s):  
Saeb M. Besarati ◽  
D. Yogi Goswami
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Solar Power ◽  
Waste Heat ◽  
Operating Conditions ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Concentrating Solar Power ◽  
Working Fluids ◽  
Supercritical Carbon

A number of studies have been performed to assess the potential of using supercritical carbon dioxide (S-CO2) in closed-loop Brayton cycles for power generation. Different configurations have been examined among which recompression and partial cooling configurations have been found very promising, especially for concentrating solar power (CSP) applications. It has been demonstrated that the S-CO2 Brayton cycle using these configurations is capable of achieving more than 50% efficiency at operating conditions that could be achieved in central receiver tower type CSP systems. Although this efficiency is high, it might be further improved by considering an appropriate bottoming cycle utilizing waste heat from the top S-CO2 Brayton cycle. The organic Rankine cycle (ORC) is one alternative proposed for this purpose, however, its performance is substantially affected by the selection of the working fluid. In this paper, a simple S-CO2 Brayton cycle, a recompression S-CO2 Brayton cycle, and a partial cooling S-CO2 Brayton cycle are first simulated and compared with the available data in the literature. Then, an ORC is added to each configuration for utilizing the waste heat. Different working fluids are examined for the bottoming cycles and the operating conditions are optimized. The combined cycle efficiencies and turbine expansion ratios are compared to find the appropriate working fluids for each configuration. It is also shown that combined recompression-ORC cycle achieves higher efficiency compared with other configurations.

Startup and Operation of a Supercritical Carbon Dioxide Brayton Cycle

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Christopher P. Sprague
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Operating Temperature ◽  
Integrated System ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Normal Operating ◽  
Wide Range ◽  
Startup Process ◽  
Supercritical Carbon

Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon dioxide (S-CO2) Brayton system at the Bettis Atomic Power Laboratory. The 100 kWe integrated system test (IST) is a two shaft recuperated closed Brayton cycle with a variable speed turbine driven compressor and a constant speed turbine driven generator using S-CO2 as the working fluid. The IST was designed to demonstrate operational, control, and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. Initial operation of the IST has proven a reliable method for startup of the Brayton loop and heatup to normal operating temperature (570 °F). An overview of the startup process, including initial loop fill and charging, and heatup to normal operating temperature is presented. Additionally, aspects of the IST startup process which are related to the loop size and component design which may be different for larger systems are discussed.

Startup and Operation of a Supercritical Carbon Dioxide Brayton Cycle

2013 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox ◽  
Christopher P. Sprague
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Operating Temperature ◽  
Integrated System ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Normal Operating ◽  
Wide Range ◽  
Startup Process ◽  
Supercritical Carbon

Bechtel Marine Propulsion Corporation (BMPC) is testing a supercritical carbon dioxide (S-CO2) Brayton system at the Bettis Atomic Power Laboratory. The 100 kWe Integrated System Test (IST) is a two shaft recuperated closed Brayton cycle with a variable speed turbine driven compressor and a constant speed turbine driven generator using S-CO2 as the working fluid. The IST was designed to demonstrate operational, control and performance characteristics of an S-CO2 Brayton power cycle over a wide range of conditions. Initial operation of the IST has proven a reliable method for startup of the Brayton loop and heatup to normal operating temperature (570°F). An overview of the startup process, including initial loop fill and charging, and heatup to normal operating temperature is presented. Additionally, aspects of the IST startup process which are related to the loop size and component design which may be different for larger systems are discussed.

Sign in / Sign up

Export Citation Format

Share Document