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.

Heat Exchanger Options for Dry Air Cooling for the sCO2 Brayton Cycle

2017 ◽  
Author(s):  
Anton Moisseytsev ◽  
Qiuping Lv ◽  
James J. Sienicki
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cost Effective ◽  
Finned Tube ◽  
Air Cooling ◽  
Brayton Cycle ◽  
Dry Air ◽  
Air Atmosphere ◽  
Air Cooler ◽  
Forced Air

The capability to utilize dry air cooling by which heat is directly rejected to the air atmosphere heat sink is one of the benefits of the supercritical carbon dioxide (sCO2) energy conversion cycle. For the selection and analysis of the heat exchanger options for dry air cooling applications for the sCO2 cycle, two leading forced air flow design approaches have been identified and analyzed for this application; an air cooler consisting of modular finned tube air coolers; and an air cooler consisting of modular compact diffusion-bonded heat exchangers. The commercially available modular finned tube air cooler is found to be more cost effective and is selected as the reference for dry air cooling.

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.

Dynamic Control Analysis of the AFR-100 SMR SFR With a Supercritical CO2 Cycle and Dry Air Cooling: Part I — Plant Control Optimization

2018 ◽  
Author(s):  
Anton Moisseytsev ◽  
James J. Sienicki
Keyword(s):  
Dynamic Control ◽  
Air Cooling ◽  
Control Analysis ◽  
Brayton Cycle ◽  
Control Mechanisms ◽  
Dry Air ◽  
Load Following ◽  
Control Optimization ◽  
Cooling Part ◽  
Plant Control

Supercritical carbon dioxide Brayton cycle power converters can benefit advanced nuclear reactors, as well as small modular reactors, by reducing the plant cost and increasing plant electrical output. The sCO2 cycles can also be designed for operation under direct dry air cooling. This paper presents the results of the coupled control analysis of a sCO2 cycle for a 100 MWe sodium-cooled fast reactor. The plant control mechanisms were investigated and optimized for load following operation.

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.

Dynamic Control Analysis of the AFR-100 SMR SFR With a Supercritical CO2 Cycle and Dry Air Cooling: Part II — Plant Control Under Varying Ambient Conditions

2018 ◽  
Author(s):  
Anton Moisseytsev ◽  
James J. Sienicki
Keyword(s):  
Dynamic Control ◽  
Ambient Air ◽  
Air Cooling ◽  
Control Analysis ◽  
Brayton Cycle ◽  
Ambient Conditions ◽  
Dry Air ◽  
Air Temperatures ◽  
Cooling Part ◽  
Plant Control

Supercritical carbon dioxide Brayton cycle power converters can benefit advanced nuclear reactors, as well as small modular reactors, by reducing the plant cost and increasing plant electrical output. The sCO2 cycles can also be designed for operation under direct dry air cooling. The paper presents the results of the coupled control analysis of a sCO2 cycle for a 100 MWe sodium-cooled fast reactor under changing ambient air temperatures. The optimum plant operation modes are identified.

Performance Evaluation of Space Solar Brayton Cycle Power Systems

1992 ◽  
Author(s):  
Zheng-Gang Diao
Keyword(s):  
Life Cycle ◽  
Power Systems ◽  
Power System ◽  
Life Cycle Cost ◽  
Pressure Ratio ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Compressor Inlet ◽  
Cycle Efficiency ◽  
System Characteristics

Unlike gas turbine power systems which consume chemical or nuclear energy, the energy consumption and/or cycle efficiency should not be a suitable criterion for evaluating the performance of space solar Brayton cycle power. A new design goal, life cycle cost, can combine all the power system characteristics, such as mass, area, and station-keeping propellant, into a unified criterion. Effects of pressure ratio, recuperator effectiveness, and compressor inlet temperature on life cycle cost were examined. This method would aid in making design choices for a space power system.

Preliminary Experimental Study of Precooler in Supercritical CO2 Brayton Cycle

2015 ◽  
Author(s):  
Seungjoon Baik ◽  
Seong Gu Kim ◽  
Seong Jun Bae ◽  
Yoonhan Ahn ◽  
Jekyoung Lee ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Power Conversion ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Test Results ◽  
Power Cycle ◽  
Compressor Inlet ◽  
House Design

The supercritical carbon dioxide (S-CO2) Brayton power conversion cycle has been receiving worldwide attention because of high thermal efficiency due to relatively low compression work near the critical point (30.98°C, 7.38MPa) of CO2. The S-CO2 Brayton cycle can achieve high efficiency with simple cycle configuration at moderate turbine inlet temperature (450∼650°C) and relatively high density of S-CO2 makes possible to design compact power conversion cycle. In order to achieve compact cycle layout, a highly compact heat exchanger such as printed circuit heat exchanger (PCHE) is widely used. Since, the cycle thermal efficiency is a strong function of the compressor inlet temperature in the S-CO2 power cycle, the research team at KAIST is focusing on the thermal hydraulic performance of the PCHE as a precooler. The investigation was performed by first developing a PCHE in-house design code named KAIST-HXD. This was followed by constructing the designed PCHE and testing it in the KAIST experimental facility, S-CO2PE. The test results of the PCHE were compared to the test results of a shell and tube type heat exchanger as well.

Second Law Analysis of a Combined Cycle With Integrated Compressor Inlet Air Cooling

2001 ◽  
Author(s):  
A. Razani ◽  
M. Patterson ◽  
K. J. Kim
Keyword(s):  
Combined Cycle ◽  
Second Law ◽  
Air Cooling ◽  
Refrigeration Cycle ◽  
Power Cycle ◽  
System Parameters ◽  
Second Law Analysis ◽  
Compressor Inlet ◽  
Environmental Air ◽  
Topping Cycle

Abstract A gas/ammonia combined cycle is proposed in which exhaust gases from a Brayton gas topping cycle are used to produce superheated ammonia in a Heat Recovery Ammonia Generator (HRAG). To increase the power of the gas turbine in the combined cycle, when the environmental air temperature is high, inlet air to the compressor is cooled in the evaporator of an ammonia refrigeration cycle added to the combined air/ammonia power cycle. In this integrated combined power cycle a small fraction of high-pressure ammonia liquid, from the exit of the ammonia pump, is used in the ammonia refrigeration cycle to cool the air. The second law analysis and optimization of the above combined cycle is presented. The effect of important system parameters on the irreversibility of components in the cycle and the exergy of exhaust streams are evaluated. Reasonable constraints for system components are assumed. The power and efficiency of the cycle are evaluated and their dependences on system parameters are presented.

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.

Effect of Compressor Inlet Pressure on Cycle Performance for a Supercritical Carbon Dioxide Brayton Cycle

2018 ◽  
Author(s):  
Eric M. Clementoni ◽  
Timothy L. Cox
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
Inlet Pressure ◽  
Cycle Performance ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Compressor Inlet ◽  
Cycle Efficiency ◽  
Supercritical Carbon

Supercritical carbon dioxide (sCO2) Brayton power cycles take advantage of the high density of CO2 near the critical point to reduce compressor power and increase cycle efficiency. However, thermophysical properties of CO2 vary drastically near the critical point. Concerns of large property variations and liquid formation within the compressor can result in sCO2 cycle designers selecting compressor inlet operating conditions substantially above the critical point, thereby reducing cycle performance. The Naval Nuclear Laboratory has built and tested the 100 kWe Integrated System Test (IST) to demonstrate the ability to operate and control an sCO2 Brayton power cycle over a wide range of conditions. Since the purpose of the IST is focused on controllability, the design compressor inlet conditions were selected to be 8.2°F (4.6°C) and 270 psi (18.4 bar) above the critical point to reduce the effect of small variations in compressor inlet temperature and pressure on density. This paper evaluates the effect of design compressor inlet pressure on cycle efficiency for a simple recuperated Brayton cycle and the performance of an operating Brayton power cycle with a fixed design over a range of compressor inlet pressures.

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