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Adil Malik - One of the best experts on this subject based on the ideXlab platform.
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Effect of helium xenon as working fluid on centrifugal compressor of power conversion unit of Closed Brayton Cycle power plant
International Journal of Hydrogen Energy, 2021Co-Authors: Adil Malik, Qun Zheng, Shafiq R. Qureshi, Asad A. Zaidi, Tasneem Yaqoob, Arif AzizAbstract:Abstract Closed Brayton Cycle (CBC) having single-shaft, centrifugal type compressor is considered as an efficient energy-conversion option associated for gas-cooled reactor (GCR) heat source. In terrestrial power plants and space power systems noble gases are considered as an efficient working fluid for most of the GCR's and CBC engines. The effectiveness of various noble gases as working fluid in Closed Cycle power plants for the power conversion units is of imperative concern. Although pure helium is relatively difficult to compress nonetheless it is measured as the best coolants for Closed Brayton Cycle power plants due to its better transport properties. Due to compression properties, its use resulted in the requirement of more mass, bigger size, higher cost and relatively more dynamic problems of rotatory machines in energy conversion system. The mixture of xenon with helium up to a molecular weight of
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Effect of helium xenon as working fluid on the compressor of power conversion unit of Closed Brayton Cycle HTGR power plant
International Journal of Hydrogen Energy, 2020Co-Authors: Adil Malik, Qun Zheng, Shafiq R. Qureshi, Asad A. ZaidiAbstract:Abstract Helium is one of the best coolants in Closed Brayton Cycle power plants as it has superior transport properties; however, the main shortcoming is its compression, which is very difficult to achieve. It leads to a higher number of compressor stages, means bigger mass and big size of the compressor, which create dynamic issues in a compressor of the power conversion unit. All the helium compressors ever constructed have a very high number of stages such as Oberhausen II type 50 MW and JAEA 300 MW, high and low pressure compressors have 25 and 35 stages respectively. In this paper thermodynamic traits of mixing helium with an inert gas xenon were presented. Helium xenon mixture up to the molecular weight of
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the design and performance analysis of highly loaded compressor of Closed Brayton Cycle htgr power plant with helium xenon gas mixture as working fluid
Progress in Nuclear Energy, 2019Co-Authors: Adil Malik, Qun Zheng, Aqiang LinAbstract:Abstract This paper evaluates the use of helium xenon binary gas mixture having molecular weight of 15 g/mole in an axial compressor of terrestrial nuclear power plants as working fluid. Pure helium is one of the best coolants due to its superior transport properties, however it is difficult to compress. Its use in high temperature gas cooled reactor (HTGR) energy conversion system leads to bigger size, more mass, higher cost and cause dynamic problems in turbomachines. In this study, detailed analysis of thermophysical properties of the binary gas mixture of helium xenon shows that the helium xenon mixture having 15 g/mole molecular weight has 7% higher heat transfer coefficient at requisite pressure and temperature. Subsequently, highly loaded helium xenon compressor is designed and performance analysis is conducted. This concludes that, only 20% stages of those in helium compressor are required to compressed the gas to the desired pressure in highly loaded helium xenon compressor. The compressor of high temperature gas cooled reactor (HTGR) working on Closed Brayton Cycle (CBC) reduced to 3 against 16 stages. Thus, in turbocompressors of HTGR power plants, use of helium xenon over pure helium is advantageous.
Michael J. Barrett - One of the best experts on this subject based on the ideXlab platform.
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Performance and Mass Modeling Subtleties in Closed-Brayton-Cycle Space Power Systems
2013Co-Authors: Michael J. Barrett, Paul K JohnsonAbstract:A number of potential NASA missions could benefit from Closed-Brayton-Cycle (CBC) power conversion systems. The human and robotic mission power applications include spacecraft, surface base, and rover scenarios. Modeling of CBC subsystems allows system engineers, mission planners and project managers to make informed decisions regarding power conversion system characteristics and capabilities. To promote thorough modeling efforts, a critical review of CBC modeling techniques is presented. Analysis of critical modeling elements, component influences and Cycle sensitivities is conducted. The analysis leads to quantitative results addressing projections on converter efficiency and overall power conversion system mass. Even moderate modeling errors are shown to easily over-predict converter efficiencies by 30% and underestimate mass estimates by 20%. Both static and dynamic modeling regimes are evaluated. Key considerations in determining model fidelity requirements are discussed. Conclusions and recommendations are presented that directly address ongoing modeling efforts in solar and nuclear space power systems.
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carbon carbon recuperators in Closed Brayton Cycle space power systems
Journal of Propulsion and Power, 2008Co-Authors: Michael J. Barrett, Paul K JohnsonAbstract:The use of carbon-carbon (C-C) recuperators in Closed-Brayton-Cycle space power conversion systems was assessed. Recuperator performance was forecast based on notional thermodynamic Cycle state values for planetary missions. Resulting thermal performance, mass and volume for plate-fin C-C recuperators were estimated and quantitatively compared with values for conventional offset-strip-fin metallic designs. Mass savings of 40– 55% were projected for C-C recuperators with effectiveness greater than 0.9 and thermal loads from 25–1400 kWt. The smaller thermal loads corresponded with lower mass savings; however, at least 50% savings were forecast for all loads above 300 kWt. System-related material challenges and compatibility issues were also discussed.
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Closed Brayton Cycle Engine Starter/Generator Cooling
3rd International Energy Conversion Engineering Conference, 2005Co-Authors: David G. Halsey, R. Scott Downing, Dam C. Nguyen, Michael J. BarrettAbstract:A Closed Brayton Cycle (CBC) engine is a prime candidate to convert heat from a reactor to electric power for space missions. The engine concept incorporates a permanent magnet starter/generator mounted on the CBC engine shaft. The starter/generator stator winding insulation system is one potential life-limiting item in the CBC engine. Successful completion of the long missions currently anticipated for the CBC engines will require temperature control of the generator stator windings to assure that these planned long lives are accomplished. Cooling flow is also required for the bearings and to remove the windage loss from the CBC. The preliminary thermal management concept for the engine is to use the CBC working fluid to provide the required cooling. This paper presents a conceptual design of a CBC turboalternator thermal management approach.
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Closed Brayton Cycle engine starter generator cooling
3rd International Energy Conversion Engineering Conference, 2005Co-Authors: David G. Halsey, Dam C. Nguyen, Scott R Downing, Michael J. BarrettAbstract:A Closed Brayton Cycle (CBC) engine is a prime candidate to convert heat from a reactor to electric power for space missions. The engine concept incorporates a permanent magnet starter/generator mounted on the CBC engine shaft. The starter/generator stator winding insulation system is one potential life-limiting item in the CBC engine. Successful completion of the long missions currently anticipated for the CBC engines will require temperature control of the generator stator windings to assure that these planned long lives are accomplished. Cooling flow is also required for the bearings and to remove the windage loss from the CBC. The preliminary thermal management concept for the engine is to use the CBC working fluid to provide the required cooling. This paper presents a conceptual design of a CBC turboalternator thermal management approach.
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Expectations of Closed-Brayton-Cycle Heat Exchangers in Nuclear Space Power Systems
Journal of Propulsion and Power, 2005Co-Authors: Michael J. BarrettAbstract:Performance expectations of Closed-Brayton-Cycle heat exchangers to be used in 100-kWe nuclear space power systems were forecast. Proposed Cycle state points for a system supporting a mission to three of Jupiter's moons required effectiveness values for the heat-source exchanger, recuperator, and rejection exchanger (gas cooler) of 0.98, 0.95, and 0.97, respectively. Performance parameters such as number of thermal units Ntu, equivalent thermal conductance UA, and entropy generation numbers Ns varied from 11 to 19, 23 to 39 kW/K, and 0.019 to 0.023 for some standard heat exchanger configurations. Pressure-loss contributions to entropy generation were significant; the largest frictional contribution was 114% of the heat-transfer irreversibility. Using conventional recuperator designs, the 0.95 effectiveness proved difficult to achieve without exceeding other performance targets; a metallic, plate-fin counterflow solution called for 15% more mass and 33% higher pressure loss than the target values. Two types of gas coolers showed promise. Single-pass counterflow and multipass cross-counterflow arrangements both met the 0.97 effectiveness requirement. Potential reliability-related advantages of the cross-counterflow design were noted. Cycle modifications, enhanced heat-transfer techniques, and incorporation of advanced materials were suggested options to reduce system development risk. Carbon-carbon sheeting or foam proved an attractive option to improve overall performance.
T. L. Ashe - One of the best experts on this subject based on the ideXlab platform.
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NUCLEAR REACTOR Closed Brayton Cycle POWER CONVERSION SYSTEM OPTIMIZATION
2014Co-Authors: T. L. Ashe, W. G. Baggenstoss, R. BonsAbstract:Extra-terrestrial exploration and development missions of the next century will require reliable, low-mass power generation modules of 100 kW, and more. These modules will be required to support both fixed-base and manned rover/explorer power needs. Low insolation levels at and beyond Mars and long periods of darkness on the moon make solar conversion less desireable for surface missions. For these missions, a Closed Brayton Cycle energy conversion system coupled with a reactor heat source is a very attractive approach. The authors conducted detailed parametric studies to assess optimized system design trends for nuclearBrayton systems as a function of operating environment and user requirements. The inherent design flexibility of the Closed Brayton Cycle energy conversion system permits ready adaptation of the system to future design constraints. This paper describes a dramatic contrast between system designs requiring man-rated radiation shielding and systems requiring instrument-rated shielding. The paper also corisiders the ramifications of using indigenous materials to provide reactor shielding for a fixed-base power souirce.
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Mission Design Drivers for Closed Brayton Cycle Space Power Conversion Configuration
Journal of Engineering for Gas Turbines and Power, 1992Co-Authors: W. G. Baggenstoss, T. L. AsheAbstract:Future space power requirements will vary from the subkilowatt range for deep space probes, to the hundreds of kilowatts range for a lunar base, to the multimegawatt range for interplanetary propulsion systems. Closed Brayton Cycle (CBC) power conversion has the flexibility to be used in all these power ranges and with a variety of heat source options such as isotope, solar, and nuclear. Each of these types of heat sources has different characteristics that make it more appropriate for particular mission profiles and power output ranges. Heat source characteristics can also be major design drivers in the Closed Brayton Cycle design optimization process. This paper explores heat source selection and the resulting CBC system designs, and discusses optimization methods as a function of the main design drivers. Such power system requirements as power level, man-rated radiation shielding, fuel costs, eclipse/darkness duration, system mass, radiator area, reliability/mission duration, and insolation level are evaluated through several CBC parametric case studies. These cases include: (1) a 500 We power system for deep space probes; (2) a 50 kWe solar dynamic system for earth orbit and other applications; (3) a 100 kWe man-rated lunar/Mars stationary /rover power system; (4) a 200 to 825 kWe power system for the lunar outpost; and (5) 3300 kWe modules for interplanetary propulsions.
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Mission Design Drivers for Closed Brayton Cycle Space Power Conversion Configuration
Volume 3: Coal Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations, 1991Co-Authors: W. G. Baggenstoss, T. L. AsheAbstract:Future space power requirements will vary from the subkilowatt range for deep space probes, to the hundreds of kilowatts range for a lunar base, to the multimegawatt range for interplanetary propulsion systems. Closed Brayton Cycle (CBC) power conversion has the flexibility to be used in all these power ranges and with a variety of heat source options such as isotope, solar, and nuclear. Each of these types of heat sources has different characteristics that make it more appropriate for particular mission profiles and power output ranges. Heat source characteristics can also be major design drivers in the Closed Brayton Cycle design optimization process.This paper explores heat source selection, the resulting CBC system designs, and discusses optimization methods as a function of the main design drivers. Such power system requirements as power level, man-rated radiation shielding, fuel costs, eclipse/darkness duration, system mass, radiator area, reliability/mission duration, and insolation level are evaluated through several CBC parametric case studies. These cases include:(1) A 500 We power system for deep space probes,(2) A 50 kWe solar dynamic system for earth orbit and other applications,(3) A 100 kWe man-rated lunar/Mars stationary/rover power system,(4) A 200 to 825 kWe power system for the lunar outpost, and(5) 3300 kWe modules for interplanetary propulsion.Copyright © 1991 by ASME
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SP100/Closed Brayton Cycle options for the lunar outpost consolidation and utilization phase stationary powerplants
1991Co-Authors: T. L. Ashe, W. G. BaggenstossAbstract:A study was conducted to examine the characteristics of lunar outpost power systems for the consolidation and utilization phases using Closed Brayton Cycle (CBC) power conversion and an SP100 nuclear reactor heat source. Three CBC system architectures using the baseline 2400 kWt SP100 reactor were examined: 1) the minimum specific mass CBC power conversion system mated to a single reactor, 2) the minimum mass, 825 kWe CBC power conversion system mated to a single reactor, and 3) an 825 kWe CBC power conversion system, using two SP100 reactors. A reliability assessment was also conducted to verify a minimum reliability of 0.977 for the power conversion unit for a 15‐year mission. The minimum specific mass was found to be 22.0 kg/kW at a total output power level of 550 kWe. This corresponds to a conversion efficiency of 23 percent. The 825 kWe, single reactor case had a specific mass of 27.2 kg/kW. The total mass of the 825 kWe, two reactor system was estimated to be approximately 4000 kg less than the mass...
Qun Zheng - One of the best experts on this subject based on the ideXlab platform.
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Effect of helium xenon as working fluid on centrifugal compressor of power conversion unit of Closed Brayton Cycle power plant
International Journal of Hydrogen Energy, 2021Co-Authors: Adil Malik, Qun Zheng, Shafiq R. Qureshi, Asad A. Zaidi, Tasneem Yaqoob, Arif AzizAbstract:Abstract Closed Brayton Cycle (CBC) having single-shaft, centrifugal type compressor is considered as an efficient energy-conversion option associated for gas-cooled reactor (GCR) heat source. In terrestrial power plants and space power systems noble gases are considered as an efficient working fluid for most of the GCR's and CBC engines. The effectiveness of various noble gases as working fluid in Closed Cycle power plants for the power conversion units is of imperative concern. Although pure helium is relatively difficult to compress nonetheless it is measured as the best coolants for Closed Brayton Cycle power plants due to its better transport properties. Due to compression properties, its use resulted in the requirement of more mass, bigger size, higher cost and relatively more dynamic problems of rotatory machines in energy conversion system. The mixture of xenon with helium up to a molecular weight of
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Effect of helium xenon as working fluid on the compressor of power conversion unit of Closed Brayton Cycle HTGR power plant
International Journal of Hydrogen Energy, 2020Co-Authors: Adil Malik, Qun Zheng, Shafiq R. Qureshi, Asad A. ZaidiAbstract:Abstract Helium is one of the best coolants in Closed Brayton Cycle power plants as it has superior transport properties; however, the main shortcoming is its compression, which is very difficult to achieve. It leads to a higher number of compressor stages, means bigger mass and big size of the compressor, which create dynamic issues in a compressor of the power conversion unit. All the helium compressors ever constructed have a very high number of stages such as Oberhausen II type 50 MW and JAEA 300 MW, high and low pressure compressors have 25 and 35 stages respectively. In this paper thermodynamic traits of mixing helium with an inert gas xenon were presented. Helium xenon mixture up to the molecular weight of
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the design and performance analysis of highly loaded compressor of Closed Brayton Cycle htgr power plant with helium xenon gas mixture as working fluid
Progress in Nuclear Energy, 2019Co-Authors: Adil Malik, Qun Zheng, Aqiang LinAbstract:Abstract This paper evaluates the use of helium xenon binary gas mixture having molecular weight of 15 g/mole in an axial compressor of terrestrial nuclear power plants as working fluid. Pure helium is one of the best coolants due to its superior transport properties, however it is difficult to compress. Its use in high temperature gas cooled reactor (HTGR) energy conversion system leads to bigger size, more mass, higher cost and cause dynamic problems in turbomachines. In this study, detailed analysis of thermophysical properties of the binary gas mixture of helium xenon shows that the helium xenon mixture having 15 g/mole molecular weight has 7% higher heat transfer coefficient at requisite pressure and temperature. Subsequently, highly loaded helium xenon compressor is designed and performance analysis is conducted. This concludes that, only 20% stages of those in helium compressor are required to compressed the gas to the desired pressure in highly loaded helium xenon compressor. The compressor of high temperature gas cooled reactor (HTGR) working on Closed Brayton Cycle (CBC) reduced to 3 against 16 stages. Thus, in turbocompressors of HTGR power plants, use of helium xenon over pure helium is advantageous.
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Effect of Reynolds number on supercritical helium axial compressor rotors performance in Closed Brayton Cycle
Energy, 2018Co-Authors: Zhitao Tian, Qun Zheng, Bin JiangAbstract:Abstract Supercritical helium has been considered as an ideal working fluid in a number of design studies for Closed Brayton Cycle due to its thermal properties. But the low density level of supercritical helium, the characteristics of the small flow channel in the turbomachine and the variable working condition method of the system determine that the compressor may run at low Reynolds number. In this paper, the influence of Reynolds number on supercritical helium compressor rotor is investigated under different conditions by numerical simulation program. Effects of specific heat ratio on Reynolds number sensitivity of supercritical helium compressor rotor are also investigated by comparing the calculated results of different working fluids. Special attention is paid to the relationship between properties of working fluids and efficiency. Then, the equations of efficiency and total pressure ratio for different working fluids are established. The results show that the Reynolds number sensitivity of supercritical helium compressor rotor decreases with the increase of tip clearance and increases with the increase of the specific heat ratio.
Daren Yu - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic analysis and parametric study of a Closed Brayton Cycle thermal management system for scramjet
International Journal of Hydrogen Energy, 2010Co-Authors: Weixing Zhou, Daren YuAbstract:A Closed Brayton Cycle thermal management system is proposed for a regeneratively cooled scramjet to reduce the hydrogen fuel flow for cooling, through converting part of the heat from fuel to other forms of energy to decrease the heat that must be taken away by hydrogen fuel. Fuel heat sink (cooling capacity) is thus indirectly increased. Instead of carrying excess fuel for cooling or seeking for any new coolant, the fuel flow for cooling is reduced, and fuel onboard is adequate to satisfy the cooling requirement for the whole hypersonic vehicle. A parametric study of an irreversible Closed Brayton Cycle thermal management system for scramjet has been performed with external as well as internal irreversibilities. It is known through performance analyses that Closed Brayton Cycle thermal management system has excellent potential performance over conventional regenerative cooling, due to the reduction in fuel flow for cooling and additional power output.