Design and Off-Design Performance of 100 kWe-Class Brayton Power Conversion Systems

Johnson, Peter; Mason, Lee S.

doi:10.1063/1.1867190

Cited by 9 publications

(4 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, some potential applications require foil bearings to operate at high pressures, in gases other than air. One such application is the closed Brayton cycle, a leading candidate for nuclear dynamic power conversion systems [2][3] [10]. This closed Brayton cycle uses a nuclear fission heat source and high pressure recirculating gas as the working fluid.…”

Section: Figure 2 -Bump-foil Type Foil Journal Bearingmentioning

confidence: 99%

High Pressure Performance of Foil Journal Bearings in Various Gases

Briggs

Prahl

Bruckner

et al. 2008

STLE/ASME 2008 International Joint Tribology Conference

View full text Add to dashboard Cite

Foil bearings offer several advantages over traditional oil-lubricated bearings in closed Brayton Cycle (CBC) systems, such as those proposed for long-term space power generation. Proposed CBCs require foil bearings to use an inert gas lubricant at pressures as high as 3.0 MPa as the bearing lubricant. The High Pressure Rig (HPR) at the NASA Glenn Research Center is used to measure foil bearing power loss using potential CBC working fluids at and beyond proposed CBC peak pressures. In the current study foil journal bearing power loss is measured in helium, nitrogen, and carbon dioxide from atmospheric pressure to 4.83 MPa and at shaft speeds from 10 krpm to 42 krpm. Bearings operating in helium show no increase in power loss with increasing pressure for the conditions tested. Bearings operating in nitrogen show increases in power loss with increasing pressure at speeds above 19 krpm, while increases in bearing power loss during carbon dioxide testing were seen at 15 krpm. At speeds above these thresholds, power loss is shown to increase more rapidly in carbon dioxide than in nitrogen. Results suggest that bearing power loss performance is dependent on both gas density and shaft speed.

show abstract

Section: Figure 2 -Bump-foil Type Foil Journal Bearingmentioning

confidence: 99%

High Pressure Performance of Foil Journal Bearings in Various Gases

Briggs

Prahl

Bruckner

et al. 2008

STLE/ASME 2008 International Joint Tribology Conference

View full text Add to dashboard Cite

show abstract

“…8 The source code originated from the NASA Glenn Research Center in-house legacy program Closed Cycle Engine Program (CCEP) and has been used in previous studies. 6,9,10,11 CCSS models all of the major CBC components (ducts, recuperator, gas cooler, turbine, compressor, alternator, radiator, and heat source) and accounts for details such as shaft bearing and windage losses and bleed flow paths. A representation of a dual Brayton, common gas system was constructed in CCSS and used to simulate steady-state off-design operating points for the purpose of further understanding the general behavior of such a system.…”

Section: Computer Modelmentioning

confidence: 99%

“…Design input parameters such as compressor inlet temperature (CIT) and pressure (400 K and 0.5 MPa), compressor pressure ratio (CPR) (2.0), turbine inlet temperature (TIT) (1150 K), recuperator and gas cooler effectiveness (95 and 97 percent), helium-xenon (He-Xe) working fluid molecular weight (40 g/mol), and component DP/P were selected based on previous studies. 3,6,9,10 The system is configured with 2 percent gas bleed flow for bearing cavity cooling and 5 percent liquid coolant bleed for alternator stator cooling. Radiator NaK mass flow rate was specified to yield the lowest combined gas cooler and radiator mass.…”

Section: B Dual Brayton Systemmentioning

confidence: 99%

Performance and Operational Characteristics for a Dual Brayton Space Power System with Common Gas Inventory

Johnson¹,

Mason

2006

4th International Energy Conversion Engineering Conference and Exhibit (IECEC)

View full text Add to dashboard Cite

“…The source code originated from the in-house legacy program Closed Cycle Engine Program (CCEP) (Barrett and Johnson, 2005;Barrett and Reid, 2004;Johnson and Mason, 2005;Klann, 1991). CCSS models all of the major BPCU components (ducts, recuperator, gas cooler, turbine, compressor, alternator, and heater) and accounts for details such as shaft bearing and windage losses and bleed flow paths.…”

Section: Modeling the Bpcu In Ccssmentioning

confidence: 99%