Long-Term Microturbine Exposure of an Advanced Alloy for Microturbine Primary Surface Recuperators

2008 ◽  
Author(s):  
Wendy J. Matthews ◽  
Karren L. More ◽  
Larry R. Walker
Keyword(s):  
Steady State ◽  
National Laboratory ◽  
Operating Conditions ◽  
Normal Operation ◽  
Operating Environment ◽  
Protective Oxide ◽  
Oak Ridge ◽  
Steady State Operation ◽  
Alloy Oxidation

Haynes Alloy HR-120 forms a protective oxide scale when exposed to the harsh operating environment of a microturbine primary surface recuperator. Primary surface recuperators manufactured from HR-120 are currently in use on the Capstone C65 MicroTurbine. Long-term microturbine tests of this alloy are currently being conducted at an elevated turbine exit temperature (∼100F° higher than normal operation) at Capstone Turbine Corporation. Alloy samples that have been tested under steady-state microturbine operating conditions are removed after pre-determined exposure intervals for characterization by Capstone Turbine Corporation in collaboration with Oak Ridge National Laboratory. Such evaluations include characterization of surface oxide scales and the associated alloy compositional changes following steady-state operation ranging from 1,800 – 14,500 hours. Results from the microstructural and compositional analyses of these long-term, steady-state engine-tested HR-120 samples are used to illustrate the progression of alloy oxidation in the microturbine operating environment.

Long-Term Microturbine Exposure of an Advanced Alloy for Microturbine Primary Surface Recuperators

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Wendy J. Matthews ◽  
Karren L. More ◽  
Larry R. Walker
Keyword(s):  
Steady State ◽  
National Laboratory ◽  
Operating Conditions ◽  
Normal Operation ◽  
Operating Environment ◽  
Protective Oxide ◽  
Oak Ridge ◽  
Steady State Operation ◽  
Alloy Oxidation

Haynes alloy HR-120 (Haynes and HR-120 are trademarks of Haynes International, Inc.) forms a protective oxide scale when exposed to the harsh operating environment of a microturbine primary surface recuperator. Primary surface recuperators manufactured from HR-120 are currently in use on the Capstone C65 MicroTurbine (MicroTurbine is a registered trademark of Capstone Turbine Corporation). Long-term microturbine tests of this alloy are currently being conducted at an elevated turbine exit temperature (∼100°F higher than that in a normal operation) at Capstone Turbine Corporation. Alloy samples that have been tested under steady-state microturbine operating conditions are removed after predetermined exposure intervals for characterization by Capstone Turbine Corporation in collaboration with Oak Ridge National Laboratory. Such evaluations include the characterization of surface oxide scales and the associated alloy compositional changes following a steady-state operation ranging from 1800 h to 14,500 h. Results from the microstructural and compositional analyses of these long-term steady-state engine-tested HR-120 samples are used to illustrate the progression of alloy oxidation in the microturbine operating environment.

Primary Surface Recuperator Alloy Oxidation: A Comparison of Accelerated Engine Testing to Field Operation

2010 ◽  
Author(s):  
Wendy J. Matthews ◽  
Karren L. More ◽  
Larry R. Walker
Keyword(s):  
Steady State ◽  
Oxide Scale ◽  
National Laboratory ◽  
Normal Operation ◽  
Protective Oxide ◽  
Oak Ridge ◽  
Alloy Oxidation ◽  
Test Engine ◽  
Engine Testing

The Capstone C65 MicroTurbine Primary Surface Recuperator (PSR) core has been manufactured from Haynes alloy HR-120 since 2005. When exposed to the harsh operating environment of the microturbine PSR, HR-120 forms a protective oxide scale that is resistant to the effects of the water vapor present in the exhaust gas. Long-term accelerated microturbine testing, with samples in a modified PSR with a removable aft dome, is on-going at an elevated Turbine Exit Temperature (TET) ∼100°F higher than normal operation. The elevated TET test engine is operated at steady state conditions and the engine is shut down at pre-determined intervals for sample removal. Material characterization of the elevated TET samples has been carried out by Capstone Turbine Corporation in collaboration with Oak Ridge National Laboratory. The surface oxide scale formation and associated alloy compositional changes have been evaluated for elevated TET samples with operating lives ranging from ∼1,800 – ∼26,500 hours. In addition, field operated HR-120 recuperators have been sectioned and samples have been evaluated for operating lives ranging from ∼5,500 – ∼18,000 hours. Results from the microstructural and compositional analyses of both the long-term steady-state elevated TET HR-120 samples, and the field operated HR-120 recuperator samples, will be presented and compared.

Primary Surface Recuperator Alloy Oxidation: A Comparison of Accelerated Engine Testing to Field Operation

2010 ◽  
Vol 133 (4) ◽  
Author(s):  
Wendy J. Matthews ◽  
Karren L. More ◽  
Larry R. Walker
Keyword(s):  
Steady State ◽  
Oxide Scale ◽  
National Laboratory ◽  
Normal Operation ◽  
Protective Oxide ◽  
Oak Ridge ◽  
Alloy Oxidation ◽  
Test Engine ◽  
Engine Testing

The Capstone C65 Microturbine primary surface recuperator (PSR) core has been manufactured from Haynes alloy HR-120 since 2005 (Microturbine is a registered trademark of Capstone Turbine Corporation; Haynes and HR-120 are trademarks of Haynes International, Inc.). When exposed to the harsh operating environment of the microturbine PSR, HR-120 forms a protective oxide scale that is resistant to the effects of the water vapor present in the exhaust gas. Long-term accelerated microturbine testing with samples in a modified PSR with a removable aft dome is ongoing at an elevated turbine exit temperature (TET) ∼100°F higher than normal operation. The elevated TET test engine is operated at steady-state conditions, and the engine is shut down at predetermined intervals for sample removal. Material characterization of the elevated TET samples has been carried out by Capstone Turbine Corporation in collaboration with Oak Ridge National Laboratory. The surface oxide scale formation and associated alloy compositional changes have been evaluated for elevated TET samples with operating lives ranging from ∼1800 h to ∼26,500 h. In addition, field-operated HR-120 recuperators have been sectioned and samples have been evaluated for operating lives ranging from ∼5500 h to ∼18,000 h. Results from the microstructural and compositional analyses of both the long-term steady-state elevated TET HR-120 samples and the field-operated HR-120 recuperator samples will be presented and compared.

scholarly journals Octane Index Applicability over the Pressure-Temperature Domain

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 607
Author(s):  
Tommy R. Powell ◽  
James P. Szybist ◽  
Flavio Dal Forno Chuahy ◽  
Scott J. Curran ◽  
John Mengwasser ◽  
...  
Keyword(s):  
High Efficiency ◽  
National Laboratory ◽  
Operating Conditions ◽  
Dominant Factor ◽  
Compression Ignition ◽  
Oak Ridge ◽  
Operating Modes ◽  
Wide Range ◽  
Thermodynamic Conditions ◽  
Si Engines

Modern boosted spark-ignition (SI) engines and emerging advanced compression ignition (ACI) engines operate under conditions that deviate substantially from the conditions of conventional autoignition metrics, namely the research and motor octane numbers (RON and MON). The octane index (OI) is an emerging autoignition metric based on RON and MON which was developed to better describe fuel knock resistance over a broader range of engine conditions. Prior research at Oak Ridge National Laboratory (ORNL) identified that OI performs reasonably well under stoichiometric boosted conditions, but inconsistencies exist in the ability of OI to predict autoignition behavior under ACI strategies. Instead, the autoignition behavior under ACI operation was found to correlate more closely to fuel composition, suggesting fuel chemistry differences that are insensitive to the conditions of the RON and MON tests may become the dominant factor under these high efficiency operating conditions. This investigation builds on earlier work to study autoignition behavior over six pressure-temperature (PT) trajectories that correspond to a wide range of operating conditions, including boosted SI operation, partial fuel stratification (PFS), and spark-assisted compression ignition (SACI). A total of 12 different fuels were investigated, including the Co-Optima core fuels and five fuels that represent refinery-relevant blending streams. It was found that, for the ACI operating modes investigated here, the low temperature reactions dominate reactivity, similar to boosted SI operating conditions because their PT trajectories lay close to the RON trajectory. Additionally, the OI metric was found to adequately predict autoignition resistance over the PT domain, for the ACI conditions investigated here, and for fuels from different chemical families. This finding is in contrast with the prior study using a different type of ACI operation with different thermodynamic conditions, specifically a significantly higher temperature at the start of compression, illustrating that fuel response depends highly on the ACI strategy being used.

Measured Torsional Vibration Characteristics of a 100 Megawatt Wind Tunnel Drive Line

1999 ◽  
Author(s):  
James M. Corliss ◽  
H. Sprysl
Keyword(s):  
Steady State ◽  
Damping Ratio ◽  
Forced Response ◽  
Operating Conditions ◽  
Pulse Load ◽  
Torsional Vibrations ◽  
Variable Frequency Drive ◽  
Steady State Operation ◽  
Torque Measurements ◽  
Torsional Analysis

Abstract A new 100 MW (135,000 Hp) adjustable speed drive system has recently been installed in the NASA Langley National Transonic Facility. The 100 MW system is the largest of its kind in the world and consists of a salient pole synchronous motor powered by a 12-pulse Load Commutated Inverter variable frequency drive. During system commissioning the drive line torsional vibrations were measured with strain gages and a telemetry-based data acquisition system. The torque measurements included drive start-up and steady-state operation at speeds where the drive motor’s pulsating torques match the drive line’s torsional natural frequency. Rapid drive acceleration rates with short dwell times were effective in reducing torsional vibrations during drive starts. Measured peak torsional vibrations during steady-state operation were comparable to predicted values and large enough to produce noticeable lateral vibrations in the drive line shafting. Cyclic shaft stresses for all operating conditions were well within the fatigue limits of the drive line components. A comparison of the torque measurements to an analytical forced response model concluded that a 0.5% critical damping ratio was appropriately applied in the drive line’s torsional analysis.

Asymptotic Analysis of a Narrow Gas-Lubricated, Flat Sector Thrust Bearing

1988 ◽  
Vol 110 (3) ◽  
pp. 427-433 ◽  
Author(s):  
J. J. Shepherd
Keyword(s):  
Steady State ◽  
Numerical Methods ◽  
Power Loss ◽  
Thrust Bearing ◽  
Center Of Pressure ◽  
Operating Conditions ◽  
Load Bearing Capacity ◽  
Steady State Operation ◽  
Bearing Number ◽  
Continuous Range

The method of matched expansions is employed to analyze the steady state operation of a finite gas-lubricated flat sector bearing for the case where the ratio of radial to circumferential dimensions is small and the relevant bearing number, Λ, is moderate. This technique yields general expressions for the pressure distribution, load bearing capacity, power loss and center of pressure location that are valid for a significant and continuous range of bearing dimensions, orientations and operating conditions. Comparisons are made, where possible, with the existing results from the literature obtained by numerical methods.

Sensitivity Study of the South Texas Project Power Plant Steady-State Simulations Using RELAP5-3D Coupled With Dakota

2012 ◽  
Author(s):  
O. A. Rodriguez ◽  
R. Vaghetto ◽  
Y. A. Hassan
Keyword(s):  
Steady State ◽  
Power Plant ◽  
Uncertainty Quantification ◽  
National Laboratory ◽  
Sandia National Laboratory ◽  
Sensitivity Study ◽  
South Texas ◽  
Normal Operation ◽  
Inlet Temperature ◽  
The South

A RELAP5-3D input deck of the South Texas Project (STP) power plant was created in order to study the thermal-hydraulic behavior of the plant during normal operation (steady-state) and during a Loss of Coolant Accident (LOCA). It is important to study the sensitivity of selected output parameters such as the total coolant mass flow rate, the peak clad temperature, the secondary pressure, as a function of specific input parameters (reactor nominal power, vessel inlet temperature, steam generators primary side heat transfer coefficient, primary pressure etc.) in order to identify the variables that play a role in the uncertainty of the thermal-hydraulic calculations. RELAP5-3D, one of the most used best estimate thermal-hydraulic system codes, was coupled with DAKOTA, developed by Sandia National Laboratory for Uncertainty Quantification and Sensitivity Analysis in order to simplify the simulation process and the analysis of the results. In the present paper, the results of the sensitivity study for selected output parameters of the steady-state simulations are presented. The coupled software was validated by repeating one set of simulations using the RELAP5-3D standalone version and by analyzing the simulation results with respect of the physical expectations and behavior of the power plant. The thermal-hydraulic parameters of interest for future uncertainty quantification calculations were identified.

VPO Transient Oxidation Kinetics

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
Gregory S. Patience ◽  
Maria-Jesus Lorences
Keyword(s):  
Steady State ◽  
Maleic Anhydride ◽  
Oxidation Rate ◽  
Circulating Fluidized Bed ◽  
Operating Conditions ◽  
Adsorption Sites ◽  
Carbon Adsorption ◽  
Reducing Conditions ◽  
Steady State Operation ◽  
Adsorbed Carbon

Transient and steady state reactor data for the partial oxidation of butane to maleic anhydride were collected in a fluid bed over DuPont commercial vanadium pyrophosphate catalyst (VPO) principally under butane rich, oxygen deficient operating conditions. Under moderate reducing conditions, oxygen becomes the determining factor for maleic anhydride productivity and selectivity. As the oxygen becomes depleted, minor changes in butane conversion impacts the selectivity substantially. However, when VPO catalyst is pre-exposed to oxygen for a substantial period of time (as practiced in Circulating Fluidized Bed technology), selectivity may be improved and maleic anhydride yields four times the steady state operation values are achieved. As the butane-to-oxygen ratio rises above 1, carbon deposits onto the surface of the catalyst, resulting in lower activity and selectivity. Based on a detailed reaction engineering model, the re-oxidation rate of the adsorbed carbon is 1st order with respect to the carbon adsorption sites and ½ order in oxygen. The re-oxidation rate of the reduced catalyst appears to be 1st order in sites and oxygen.

scholarly journals New Retinas for Old

2003 ◽  
Vol 125 (10) ◽  
pp. 42-46 ◽  
Author(s):  
Gayle Ehrenman
Keyword(s):  
Private Sector ◽  
Human Body ◽  
Microelectrode Array ◽  
National Laboratory ◽  
Retinal Prosthesis ◽  
Artificial Retina ◽  
Oak Ridge ◽  
Retinal Tissue ◽  
The Brain

This article reviews retinal prosthesis that is a seeing-eye chip with as many as 1000 tiny electrodes to be implanted in the eye. It has the potential to help people who have lost their sight regain enough vision to function independently in the sighted world. The Artificial Retina Project is a collaboration of five US National laboratories, three universities, and the private sector. The interface module and the antenna for future versions of the retinal prosthesis will all be implanted in the eye, instead of outside the eye. The retinal prosthesis will help patients who still have neutral wiring from the eye to the brain. One of the challenges in developing the device is creating a microelectrode array that conforms to the curved shape of the retina, without damaging the delicate retinal tissue. Oak Ridge National Laboratory in Oak Ridge, Tennessee, is the lead lab on the Artificial Retina Project. They're the folks responsible for fabricating and testing the electrodes, and making sure they're up to the challenge of being implanted long term in a human body.

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