The Experts below are selected from a list of 81315 Experts worldwide ranked by ideXlab platform
Rodney John Allam - One of the best experts on this subject based on the ideXlab platform.
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demonstRation of the allam cycle an update on the development status of a high efficiency supercritical carbon dioxide power process employing full carbon capture
Energy Procedia, 2017Co-Authors: Rodney John Allam, Scott Thomas Martin, Brock Alan Forrest, Jeremy Eron Fetvedt, Xijia LuAbstract:Abstract The Allam cycle is a novel CO2, oxy-fuel power cycle that utilizes hydrocarbon fuels while inherently capturing approximately 100% of atmospheric emissions, including nearly all CO2 emissions at a cost of electricity that is highly competitive with the best available energy production systems that do not employ CO2 capture. The proprietary system achieves these results through a semi-closed-loop, high-Pressure, Low-Pressure-Ratio recuperated Brayton cycle that uses supercritical CO2 as the working fluid, dramatically reducing energy losses compared to steam- and air-based cycles. In conventional cycles, the sepaRation and removal of Low concentRation combustion derived impurities such as CO2 results in a large additional capital cost and increased parasitic power. As a result, removal in conventional cycles can increase the cost of electricity by 50% to 70% [1] . The compelling economics of the Allam Cycle are driven by high target efficiencies, 59% net for natural gas and 51% net for coal (LHV basis) while inherently capturing nearly 100% CO2 at pipeline Pressure with Low projected capital and OM for the demonstRation plant, the construction and commissioning status, schedule, key components, layout, and detailed design; turbine design, manufacturing status; development of a novel dynamic control system and control simulator for the demonstRation plant; and other key aspects of the cycle. It will provide an update on the progress of the gasified solid fuel Allam Cycle and then address the overall Allam Cycle commercialization program, benefits and applications, and the expected design of the natural gas 300 MWe commercial NET Power plant projected for 2020.
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high efficiency and Low cost of electricity geneRation from fossil fuels while eliminating atmospheric emissions including carbon dioxide
Energy Procedia, 2013Co-Authors: Rodney John Allam, Jeremy Eron Fetvedt, Miles R Palmer, William G Brown, David Freed, Hideo Nomoto, Masao Itoh, Nobuo Okita, Charles JonesAbstract:Abstract NET Power has developed a novel, oxy-fuel thermodynamic power cycle [1] that uses hydrocarbon fuels, captures 100% of atmospheric emissions, including all carbon dioxide, and has a cost of electricity that is highly competitive with the best current systems that do not have CO2 capture. The proprietary system achieves these results through a closed-loop, high-Pressure, Low-Pressure-Ratio recuperated Brayton cycle that uses supercritical CO2 as the working fluid. The cycle exploits the special thermodynamic properties of carbon dioxide as a working fluid by eliminating the energy losses that steam-based cycles encounter due to the heat of vaporization and condensation. The compelling economics of the system are driven by high target efficiencies – 59% net LHV for natural gas and 51% net LHV for coal – and Low projected capital and O&M costs, which are the result of utilizing only a single turbine, having a smaller plant footprint, and requiring fewer, smaller components than comparable fossil-fuel systems. NET Power, Toshiba CorpoRation, Exelon CorpoRation, and the Shaw Power Group are partnering to commercialize this system by developing a 50MWt facility that is scheduled to begin testing in 2014. This facility will generate electricity from natural gas and capture 100% of emissions, including all CO2. The initial design for a commercial system with an electrical output in the range of 200MWt to 500MWt is also under development. The turbine for the 50MWt plant is being designed at the 500MWt level and then scaled down for the demonstRation plant to facilitate rapid development of the large-scale turbine in the future. The demonstRation plant will test all components and control systems and the operability of the cycle, including 100% capture of carbon dioxide and other impurities, using a range of fuel gas compositions. The NET Power cycle will have an important impact on the power industry's ability to control and limit greenhouse gas emissions. Driven by its competitive cost when compared to state-of-the-art technologies without CO2 capture, the authors believe the NET Power cycle will remove economic barriers to the deployment of 100%-carbon-capture, fossil-fuel-based electricity geneRation technology. This will enable both the developed and developing world to produce cheap electricity that does not contribute to CO2-based climate change.
Xijia Lu - One of the best experts on this subject based on the ideXlab platform.
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demonstRation of the allam cycle an update on the development status of a high efficiency supercritical carbon dioxide power process employing full carbon capture
Energy Procedia, 2017Co-Authors: Rodney John Allam, Scott Thomas Martin, Brock Alan Forrest, Jeremy Eron Fetvedt, Xijia LuAbstract:Abstract The Allam cycle is a novel CO2, oxy-fuel power cycle that utilizes hydrocarbon fuels while inherently capturing approximately 100% of atmospheric emissions, including nearly all CO2 emissions at a cost of electricity that is highly competitive with the best available energy production systems that do not employ CO2 capture. The proprietary system achieves these results through a semi-closed-loop, high-Pressure, Low-Pressure-Ratio recuperated Brayton cycle that uses supercritical CO2 as the working fluid, dramatically reducing energy losses compared to steam- and air-based cycles. In conventional cycles, the sepaRation and removal of Low concentRation combustion derived impurities such as CO2 results in a large additional capital cost and increased parasitic power. As a result, removal in conventional cycles can increase the cost of electricity by 50% to 70% [1] . The compelling economics of the Allam Cycle are driven by high target efficiencies, 59% net for natural gas and 51% net for coal (LHV basis) while inherently capturing nearly 100% CO2 at pipeline Pressure with Low projected capital and OM for the demonstRation plant, the construction and commissioning status, schedule, key components, layout, and detailed design; turbine design, manufacturing status; development of a novel dynamic control system and control simulator for the demonstRation plant; and other key aspects of the cycle. It will provide an update on the progress of the gasified solid fuel Allam Cycle and then address the overall Allam Cycle commercialization program, benefits and applications, and the expected design of the natural gas 300 MWe commercial NET Power plant projected for 2020.
Ca Hall - One of the best experts on this subject based on the ideXlab platform.
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Fan aerodynamics with a short intake at high angle of attack
2020Co-Authors: Mohankumar B, Ca Hall, Mj WilsonAbstract:Future turbofan engines seek shorter intakes to reduce the cruise fuel burn of a Low Pressure Ratio, large diameter fan. However, shorter intakes increase the level of fLow distortion entering the rotor when the aircraft angle of attack (AOA) is high, reducing thrust when critically needed. This paper considers how the fan rotor radial Pressure Ratio distribution and tip velocity triangle can be designed to improve thrust at high AOA. Full annulus, unsteady CFD is performed on three rotor designs coupled to a short intake. We show that rotor design for high AOA should be guided by three fLow mechanisms. Mechanism i) is caused by high Mach number fLow over the bottom intake lip, which chokes the rotor leading to high loss. Mechanism ii) is the loss geneRation in the rotor tip as it passes through an intake sepaRation. Mechanism iii) shows radial fLows through the rotor change both the amount and the way work is imparted on the fLow. Two comparable rotor design philosophies for high thrust are proposed; high work or Low loss. Rotors designed to a mid-high radial Pressure Ratio distribution impart high work on streamlines that migrate radially towards the hub and exit the rotor at highly cambered sections. Meanwhile, tip-high designs reduce choking losses in the midspan when operating with a separated intake, particularly when the tip velocity triangle is designed to high axial velocity diffusion over high camber. However, such designs suffer with higher tip losses after exiting an intake sepaRation
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Reverse Thrust Aerodynamics of Variable Pitch Fans
American Society of Mechanical Engineers, 2019Co-Authors: Ts Williams, Ca HallAbstract:© 2019 by ASME. Variable pitch fans are of interest for future Low-Pressure Ratio fan systems since they provide improved operability relative to fixed pitch fans. If they can also be re-pitched such that they generate sufficient reverse thrust they could eliminate the engine drag and weight penalty associated with bypass duct thrust reversers. This paper sets out to understand the details of the 3D fan stage fLow field in reverse thrust opeRation. This study uses the Advanced Ducted Propulsor variable pitch fan test case, which has a design fan Pressure Ratio of 1.29. Comparison with spanwise probe measurements show that the computational approach is valid for examining the variation of loss and work in the rotor in forward thrust. The method is then extended to a reverse thrust configuRation using an extended domain and appropriate boundary conditions. Computations, run at two rotor stagger settings, show that the spanwise variation in relative fLow angle onto the rotor aligns poorly to the rotor inlet metal angle. This leads to two dominant rotor loss sources: one at the tip associated with positive incidence and the second caused by negative incidence at Lower span fractions. The second loss is reduced by opening the rotor stagger setting, and the first increases with rotor suction surface Mach number. The higher mass fLow at more open rotor settings provide higher gross thrust, up to 49% of the forward take-off value, but is limited by the increased loss at high speed
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Stall Inception in Low-Pressure Ratio Fans
American Society of Mechanical Engineers, 2019Co-Authors: Kim S, Rp Grewe, Mj Wilson, Pullan G, Ca Hall, Gunn EAbstract:© 2019 by ASME. A combined experimental and computational test program, with two Low-Pressure Ratio aero-engine fans, has been used to identify the fLow mechanisms at stall inception and the subsequent stall cell growth. The two fans have the same rotor tip clearance, annulus design, and downstream stators, but different levels of tip loading. The measurement data show that both the fans stall via spike-type inception, but that the growth of the stall cell and the final cell size is different in each fan. The computations, reproducing both the qualitative and quantitative behavior of the steady-state and transient measurements, are used to identify the fLow mechanisms at the origin of stall inception. In one fan, spillage of tip leakage fLow upstream of the leading edge plane is responsible. In the other, sudden growth of casing corner sepaRation blockage leads to stall. These two mechanisms are in accord with the findings from core compressors. However, the transonic aerodynamics and the Low hub-to-tip radius Ratio of the fans lead to the folLowing two findings: first, the casing corner sepaRation is driven by shock-boundary layer interaction and second, the spanwise loading distribution of the fan determines whether the spike develops into full-span or part-span stall and both types of behavior are represented in the present work. Finally, the axial momentum flux of the tip clearance fLow is shown to be a useful indicator of the leakage jet spillage mechanism. A simple model is provided that links the tip loading, stagger, and solidity with the tip clearance axial momentum flux, thereby alLowing the aerodynamicist to connect, qualitatively, design parameters with the stall behavior of the fan
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Reverse Thrust Aerodynamics of Variable Pitch Fans
American Society of Mechanical Engineers, 2019Co-Authors: Ts Williams, Ca HallAbstract:Variable pitch fans are of interest for future Low-Pressure Ratio fan systems since they provide improved operability relative to fixed pitch fans. If they can also be re-pitched such that they generate sufficient reverse thrust they could eliminate the engine drag and weight penalty associated with bypass duct thrust reversers. This paper sets out to understand the details of the 3D fan stage fLow field in reverse thrust opeRation. This study uses the Advanced Ducted Propulsor variable pitch fan test case, which has a design fan Pressure Ratio of 1.29. Comparison with spanwise probe measurements show that the computational approach is valid for examining the variation of loss and work in the rotor in forward thrust. The method is then extended to a reverse thrust configuRation using an extended domain and appropriate boundary conditions. Computations, run at two rotor stagger settings, show that the spanwise variation in relative fLow angle onto the rotor aligns poorly to the rotor inlet metal angle. This leads to two dominant rotor loss sources: one at the tip associated with positive incidence and the second caused by negative incidence at Lower span fractions. The second loss is reduced by opening the rotor stagger setting, and the first increases with rotor suction surface Mach number. The higher mass fLow at more open rotor settings provide higher gross thrust, up to 49% of the forward take-off value, but is limited by the increased loss at high speed
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Stall inception in Low Pressure Ratio fans
2018Co-Authors: Kim S, Rp Grewe, Mj Wilson, Pullan G, Ca Hall, Gunn EAbstract:Copyright © 2018 ASME. A combined experimental and computational test programme, with two Low Pressure Ratio aero-engine fans, has been used to identify the fLow mechanisms at stall inception and the subsequent stall cell growth. The two fans have the same rotor tip clearance, annulus design and downstream stators, but different levels of tip loading. The measurement data show that both fans stall via spike-type inception, but that the growth of the stall cell, and the final cell size, is different in each fan. The computations, reproducing both the qualitative and quantitative behaviour of the steady-state and transient measurements, are used to identify the fLow mechanisms at the origin of stall inception. In one fan, spillage of tip leakage fLow upstream of the leading edge plane is responsible. In the other, sudden growth of casing corner sepaRation blockage leads to stall. These two mechanisms are in accord with the findings from core compressors. However, the transonic aerodynamics and Low hub-to-tip radius Ratio of the fans leads to the folLowing two findings: First, the casing corner sepaRation is driven by shock-boundary layer interaction; second, the spanwise loading distribution of the fan determines whether the spike develops into full-span or part-span stall and both types of behaviour are represented in the present work. Finally, the axial momentum flux of the tip clearance fLow is shown to be a useful indicator of the leakage jet spillage mechanism. A simple model is provided that links the tip loading, stagger and solidity with the tip clearance axial momentum flux, thereby alLowing the aerodynamicist to connect, qualitatively, design parameters with the stall behaviour of the fan
Jeremy Eron Fetvedt - One of the best experts on this subject based on the ideXlab platform.
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demonstRation of the allam cycle an update on the development status of a high efficiency supercritical carbon dioxide power process employing full carbon capture
Energy Procedia, 2017Co-Authors: Rodney John Allam, Scott Thomas Martin, Brock Alan Forrest, Jeremy Eron Fetvedt, Xijia LuAbstract:Abstract The Allam cycle is a novel CO2, oxy-fuel power cycle that utilizes hydrocarbon fuels while inherently capturing approximately 100% of atmospheric emissions, including nearly all CO2 emissions at a cost of electricity that is highly competitive with the best available energy production systems that do not employ CO2 capture. The proprietary system achieves these results through a semi-closed-loop, high-Pressure, Low-Pressure-Ratio recuperated Brayton cycle that uses supercritical CO2 as the working fluid, dramatically reducing energy losses compared to steam- and air-based cycles. In conventional cycles, the sepaRation and removal of Low concentRation combustion derived impurities such as CO2 results in a large additional capital cost and increased parasitic power. As a result, removal in conventional cycles can increase the cost of electricity by 50% to 70% [1] . The compelling economics of the Allam Cycle are driven by high target efficiencies, 59% net for natural gas and 51% net for coal (LHV basis) while inherently capturing nearly 100% CO2 at pipeline Pressure with Low projected capital and OM for the demonstRation plant, the construction and commissioning status, schedule, key components, layout, and detailed design; turbine design, manufacturing status; development of a novel dynamic control system and control simulator for the demonstRation plant; and other key aspects of the cycle. It will provide an update on the progress of the gasified solid fuel Allam Cycle and then address the overall Allam Cycle commercialization program, benefits and applications, and the expected design of the natural gas 300 MWe commercial NET Power plant projected for 2020.
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high efficiency and Low cost of electricity geneRation from fossil fuels while eliminating atmospheric emissions including carbon dioxide
Energy Procedia, 2013Co-Authors: Rodney John Allam, Jeremy Eron Fetvedt, Miles R Palmer, William G Brown, David Freed, Hideo Nomoto, Masao Itoh, Nobuo Okita, Charles JonesAbstract:Abstract NET Power has developed a novel, oxy-fuel thermodynamic power cycle [1] that uses hydrocarbon fuels, captures 100% of atmospheric emissions, including all carbon dioxide, and has a cost of electricity that is highly competitive with the best current systems that do not have CO2 capture. The proprietary system achieves these results through a closed-loop, high-Pressure, Low-Pressure-Ratio recuperated Brayton cycle that uses supercritical CO2 as the working fluid. The cycle exploits the special thermodynamic properties of carbon dioxide as a working fluid by eliminating the energy losses that steam-based cycles encounter due to the heat of vaporization and condensation. The compelling economics of the system are driven by high target efficiencies – 59% net LHV for natural gas and 51% net LHV for coal – and Low projected capital and O&M costs, which are the result of utilizing only a single turbine, having a smaller plant footprint, and requiring fewer, smaller components than comparable fossil-fuel systems. NET Power, Toshiba CorpoRation, Exelon CorpoRation, and the Shaw Power Group are partnering to commercialize this system by developing a 50MWt facility that is scheduled to begin testing in 2014. This facility will generate electricity from natural gas and capture 100% of emissions, including all CO2. The initial design for a commercial system with an electrical output in the range of 200MWt to 500MWt is also under development. The turbine for the 50MWt plant is being designed at the 500MWt level and then scaled down for the demonstRation plant to facilitate rapid development of the large-scale turbine in the future. The demonstRation plant will test all components and control systems and the operability of the cycle, including 100% capture of carbon dioxide and other impurities, using a range of fuel gas compositions. The NET Power cycle will have an important impact on the power industry's ability to control and limit greenhouse gas emissions. Driven by its competitive cost when compared to state-of-the-art technologies without CO2 capture, the authors believe the NET Power cycle will remove economic barriers to the deployment of 100%-carbon-capture, fossil-fuel-based electricity geneRation technology. This will enable both the developed and developing world to produce cheap electricity that does not contribute to CO2-based climate change.
D D Ganji - One of the best experts on this subject based on the ideXlab platform.
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investigation of film cooling on nose cone by a forward facing array of micro jets in hypersonic fLow
International Communications in Heat and Mass Transfer, 2015Co-Authors: Barzegar M Gerdroodbary, Misagh Imani, D D GanjiAbstract:Abstract A numerical study has been performed to investigate the film-cooling heat reduction performance of a single jet (diameter 2 mm and 0.9 mm), and an array forward facing of micro-jets (diameter 300 μm each) of the same effective area (corresponding to the respective single jet). Helium and/or Nitrogen are injected as coolant gases from the tip of the nose through an array of micro into a Mach 5.9 counterfLow free stream. Parametric studies were conducted on injection total Pressure with various diameters by using the Reynolds-averaged Navier–Stokes equations with Menter's Shear Stress Transport turbulence model. Complex jet interactions were found in the injection region with a variety of fLow features depending upon the specific configuRation. These fLow features were found to have subtle effects on the overall system performance. Total heat load reductions of up to 40% over a nose were achieved for micro jet with Low Pressure Ratio. Significant wall heat transfer reductions were also found in all cases. The heat transfer rates were strongly influenced by injection mass fLow rate, and only moderately affected by the number of micro jets. The maximum heat reduction performance was found in the highest injection total jet Pressure (consequently more mass fLow rate) with the highest micro array.
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heat reduction using conterfLowing jet for a nose cone with aerodisk in hypersonic fLow
Aerospace Science and Technology, 2014Co-Authors: Barzegar M Gerdroodbary, Misagh Imani, D D GanjiAbstract:Abstract Numerical simulations of a 2D axisymmetric aerodisked nose cone in hypersonic fLow are conducted, and innovative techniques involving forward injection of the gas from the stagnation point of the sphere are investigated; techniques include the injection of various counterfLowing jets (helium or carbon dioxide) as a coolant jet from the nose cone behind the aerodisk. In this study, the characteristics of the various jet conditions of a counterfLowing jet on a cone surface were investigated numerically to improve performance of the jet on heat reduction at the surface of a nose. The compressible, unsteady, axisymmetric Navier–Stokes equations are solved with SST turbulence model for free stream Mach number of 5.75 at 0° angle of attack with and without gas injection. According to the investigation of various conditions of jets, important phenomena of fLow field and some effective jet conditions are found. Heat transfer results show a significant reduction in heat flux, even giving negative heat flux for some Low Pressure Ratio, indicating that the fLow wetting the model had a cooling effect which could significantly impact thermal protection system design. The findings suggest that high-speed vehicle design and performance can benefit from the application of counterfLowing jets as a cooling system.
