Brayton Cycle As an Alternate Power Conversion Option for Sodium Cooled Fast Reactor

2019 ◽  
Author(s):  
Jofred Joseph ◽  
Satish Kumar ◽  
Tanmay Vasal ◽  
N. Theivarajan
Keyword(s):  
Power Conversion ◽  
Rankine Cycle ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Generation System ◽  
Fast Reactors ◽  
Turbine Inlet Temperature ◽  
Power Cycle ◽  
Power Generation System ◽  
Cycle Efficiency

Abstract Enhancing the safety and economic competitiveness are major objectives in the development of advanced reactor designs with emphasis on the design of systems or components of the nuclear systems. Innovative power cycle development is another potential option to achieve these objectives. Sodium cooled fast reactor (SFR) is one among the six reactor design concepts identified by the Gen IV International Forum for development to meet the technology goals for new nuclear energy system. Similar to the power cycle used in conventional fossil fuel based thermal power plants, sodium-cooled fast reactors have adopted the Rankine cycle based power conversion system. However, the possibility of sodium water reaction is a major concern and it becomes necessary to adopt means of early detection of leaks and isolation of the affected SG module for mitigating any adverse impact of sodium water reaction. The high exothermic nature of the reaction calls for introducing an intermediate sodium heat transport loop, leading to high overall plant cost hindering commercialization of sodium fast reactors. The Indian Prototype Fast Breeder Reactor (PFBR) also uses Rankine cycle in the power generation system. The superheated steam temperature has been set at 490 degree Celsius based on optimisation studies and material limitations. Additional Fast Breeder reactors are planned in near future and further work is being done to develop more advanced sodium cooled fast reactors. The closed Brayton cycle is a promising alternative to conventional Rankine cycle. By selecting an inert gas or a gas with milder reaction with sodium, the vigorous sodium water reaction can be avoided and significant cost savings in the turbine island can be achieved as gas turbine power conversion systems are of much smaller size than comparable steam turbine systems due to their higher power density. In the study, various Brayton cycle designs on different working gases have been explored. Supercritical-CO2 (s-CO2), helium and nitrogen cycle designs are analyzed and compared in terms of cycle efficiency, component performance and physical size. The thermal efficiencies at the turbine inlet temperature of Indian PFBR have been compared for Rankine cycle and Brayton cycle based on different working fluids. Also binary mixtures of different gases are investigated to develop a more safe and efficient power generation system. Helium does not interact with sodium and other structural materials even at very high temperatures but its thermal performance is low when compared to other fluids. Nitrogen being an inert gas does not react with sodium and can serve to utilise existing turbomachinery because of the similarity with atmospheric air. The supercritical CO2 based cycle has shown best thermodynamic performance and efficiency when compared to other Brayton cycles for the turbine inlet temperature of Indian PFBR. CO2 also reacts with sodium but the reaction is mild compared to sodium water reaction. The cycle efficiency of the s-CO2 cycle can be further improved by adopting multiple reheating, inter cooling and recuperation.

Proposal of Innovative Gas Turbine Combined Cycle Power Generation System

2004 ◽  
Author(s):  
Hideto Moritsuka
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Generation System ◽  
Turbine Inlet Temperature ◽  
Turbine Inlet ◽  
Power Generation System

In order to estimate the possibility to improve thermal efficiency of power generation use gas turbine combined cycle power generation system, benefits of employing the advanced gas turbine technologies proposed here have been made clear based on the recently developed 1500C-class steam cooling gas turbine and 1300C-class reheat cycle gas turbine combined cycle power generation systems. In addition, methane reforming cooling method and NO reducing catalytic reheater are proposed. Based on these findings, the Maximized efficiency Optimized Reheat cycle Innovative Gas Turbine Combined cycle (MORITC) Power Generation System with the most effective combination of advanced technologies and the new devices have been proposed. In case of the proposed reheat cycle gas turbine with pressure ratio being 55, the high pressure turbine inlet temperature being 1700C, the low pressure turbine inlet temperature being 800C, combined with the ultra super critical pressure, double reheat type heat recovery Rankine cycle, the thermal efficiency of combined cycle are expected approximately 66.7% (LHV, generator end).

scholarly journals Thermal Performance Analysis of a Direct-Heated Recompression Supercritical Carbon Dioxide Brayton Cycle Using Solar Concentrators

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4358 ◽  
Author(s):  
Jinping Wang ◽  
Jun Wang ◽  
Peter D. Lund ◽  
Hongxia Zhu
Keyword(s):  
Incidence Angle ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Turbine Inlet Temperature ◽  
Beam Radiation ◽  
Solar Concentrators ◽  
Cooling Temperature ◽  
Turbine Inlet ◽  
Cycle Efficiency

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.

Advanced High Temperature Gas-Cooled Reactor Systems

2008 ◽  
Author(s):  
Yasuyoshi Kato
Keyword(s):  
Gas Turbine ◽  
Power Conversion ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Co2 Gas ◽  
Flow Channels ◽  
Turbine Inlet ◽  
Conversion System ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency

Three systems have been proposed for advanced high temperature gas-cooled reactors (HTGRs): a supercritical carbon dioxide (S-CO2) gas turbine power conversion system; a new MicroChannel Heat Exchanger (MCHE); and a once-through-then-out (OTTO) refueling scheme with burnable poison (BP) loading. An S-CO2 gas turbine cycle attains higher cycle efficiency than a He gas turbine cycle due to reduced compression work around the critical point of CO2. Considering temperature lowering at the turbine inlet by 30°C through the intermediate heat exchange, the S-CO2 indirect cycle achieves efficiency of 53.8% at turbine inlet temperature of 820°C and turbine inlet pressure of 20 MPa. This cycle efficiency value is higher by 4.5% than that (49.3%) of a He direct cycle at turbine inlet temperature of 850°C and 7 MPa. A new MCHE has been proposed as intermediate heat exchangers between the primary cooling He loop and the secondary S-CO2 gas turbine power conversion system; and recuperators of the S-CO2 gas turbine power conversion system. This MCHE has discontinuous “S”-shape fins providing flow channels with near sine curves. Its pressure drop is one-sixth reference to the conventional MCHE with zigzag flow channel configuration while the same high heat transfer performance inherits. The pressure drop reduction is ascribed to suppression of recirculation flows and eddies that appears around bend corners of zigzag flow channels in the conventional MCHE. An optimal BP loading in an OTTO refueling scheme eliminates the drawback of its excessively high axial power peaking factor, reducing the power peaking factor from 4.44 to about 1.7; and inheriting advantages over the multi-pass scheme because of the lack of fuel handling and integrity checking systems; and reloading. Because of the power peaking factor reduction, the maximum fuel temperatures are lower than the maximum permissible values of 1250°C for normal operation and 1600°C during a depressurization accident.

Analysis and Optimization of ORC for Low-Temperature Waste Heat Power Generation

2011 ◽  
Vol 383-390 ◽  
pp. 6614-6620
Author(s):  
Xin Ling Ma ◽  
Xiang Rui Meng ◽  
Xin Li Wei ◽  
Jia Chang ◽  
Hui Li
Keyword(s):  
Power Generation ◽  
Low Temperature ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Heat Power ◽  
Generation System ◽  
Power Generation System

This paper presents energy analysis, thermodynamic calculation and exergy analysis for waste heat power generation system of Organic Rankine Cycle based on the first and second laws of thermodynamics. In order to improve system performance, for low-temperature waste heat of 120°C and R245fa organic working fluid, using Aspen Plus software conducted simulation, optimization and improvement. Results from these analyses show that decreasing the expander inlet temperature, increasing inlet pressure of the expander, and adding regenerative heater can increase thermal and exergy efficiencies, at the same time reduce system irreversibility.

High-Efficiency Solar Dynamic Space Power Generation System

1991 ◽  
Vol 113 (3) ◽  
pp. 131-137 ◽  
Author(s):  
Aristide Massardo
Keyword(s):  
Power Generation ◽  
Power Systems ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Generation System ◽  
Dynamic Power ◽  
Power Generation System

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.

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.

Advanced High Temperature Gas-Cooled Reactor Systems

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Yasuyoshi Kato
Keyword(s):  
Gas Turbine ◽  
Power Conversion ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Co2 Gas ◽  
Flow Channels ◽  
Turbine Inlet ◽  
Conversion System ◽  
Gas Turbine Cycle ◽  
Cycle Efficiency

Three systems have been proposed for advanced high-temperature gas-cooled reactors: a supercritical carbon dioxide (S-CO2) gas turbine power conversion system, a new microchannel heat exchanger (MCHE), and a once-through-then-out (OTTO) refueling scheme with burnable poison (BP) loading. A S-CO2 gas turbine cycle attains higher cycle efficiency than a He gas turbine cycle because of reduced compression work around the critical point of CO2. Considering temperature reduction at the turbine inlet by 30°C through intermediate heat exchange, the S-CO2 indirect cycle achieves an efficiency of 53.8% at a turbine inlet temperature of 820°C and a turbine inlet pressure of 20 MPa. This cycle efficiency value is higher by 4.5% than that (49.3%) of a He direct cycle at a turbine inlet temperature of 850°C and 7 MPa. A new MCHE has been proposed as an intermediate heat exchanger between the primary cooling He loop and the secondary S-CO2 gas turbine power conversion system and as recuperators of the S-CO2 gas turbine power conversion system. This MCHE has discontinuous “S-shaped” fins providing flow channels resembling sine curves. Its pressure drop is one-sixth that of a conventional MCHE with a zigzag flow channel configuration, but it has the same high heat transfer performance. The pressure drop reduction is ascribed to suppression of recirculation flows and eddies that appear around bend corners of the zigzag flow channels in the conventional MCHE. An optimal BP loading in an OTTO refueling scheme eliminates the shortcoming of its excessively high axial power peaking factor, reducing the power peaking factor from 4.44 to about 1.7, and inheriting advantages over the multipass scheme because it obviates reloading in addition to fuel handling and integrity checking systems. Because of the power peaking factor reduction, the maximum fuel temperatures are lower than the maximum permissible values of 1250°C for normal operation and 1600°C during a depressurization accident.

Approximate Relations for Optimum Turbine Operating Parameters in Allam Cycle

2020 ◽  
Author(s):  
Yousef Haseli
Keyword(s):  
Turbine Blades ◽  
Air Separation ◽  
Cycle Performance ◽  
Working Fluid ◽  
Operating Parameters ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Power Cycle ◽  
Turbine Inlet ◽  
Cycle Efficiency

Abstract The Allam power cycle is a novel method for clean power generation which employs the concept of oxyfuel combustion with carbon dioxide as the main working fluid. To date, only a few studies have appeared in the literature in that the performance of the Allam cycle has been assessed using a commercial software. The objective of this article is to explore relations between the cycle performance and the main operating parameters of the Allam cycle through a simplified thermodynamic analysis and mathematical modeling. The cycle efficiency is maximized with respect to turbine parameters. Expressions are derived for estimation of optimum turbine inlet temperature and pressure as well as optimum turbine exhaust pressure. Main simplifications include no portion of the recycled CO2 is used for turbine blades cooling and single stage CO2 compressor without intercooling. The cryogenic air separation process developed by Allam is employed which produces supercritical oxygen at combustion pressure. Typical numerical results are presented using the new expressions for optimum turbine parameters. The highest cycle efficiency is found to be 66.4% at a turbine inlet temperature/inlet pressure/exhaust pressure of 1306 K/300 bar/39.4 bar and a CO2 compressor exit pressure of 60 bar. The newly derived relationships among the key process parameters allow a better understanding of the operation of Allam cycle.

Integration and Optimization of Supercritical Carbon Dioxide Brayton Cycle and Goswami Cycle

2019 ◽  
Author(s):  
Diego Guillen ◽  
Martina Leveni ◽  
Giampaolo Manfrida ◽  
Marco Sanjuan
Keyword(s):  
Waste Heat ◽  
Thermodynamic Cycle ◽  
Energy System ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Cost Of Energy ◽  
Space Cooling ◽  
The Cost ◽  
Cycle Efficiency

Abstract Utilization of waste heat from an energy conversion process is a key step in improving the overall energy system conversion efficiency and reducing the cost of energy. Since a supercritical CO2 Brayton power cycle is being considered as an important cycle for the conversion of solar energy to power, we propose to utilize the heat rejected from this cycle to feed a bottoming thermodynamic cycle. Goswami cycle can utilize the low temperature waste heat to produce both power and cooling in the same loop. Moreover, refrigeration and space cooling are usually more expensive than heating in most applications. This paper describes the modeling and simulation results of the combined Brayton and Goswami cycles. The mass flow ratio of the two cycles is determined by the heat exchanger effectiveness method, constraining the minimum allowed temperature difference. The operating parameters that yield the best performance in terms of overall cycle efficiency, net work, and cooling outputs were found through the optimization of a numerical model developed in MATLAB. The cooling production in the Goswami cycle is maximized at the expense of the net work in order to produce the maximum refrigeration output. A maximum combined efficiency for power and cooling generation above 45% can be found when the inlet temperature at the Brayton cycle is set at 700 °C.

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