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Sample records for air compressor discharge

  1. Compressor discharge bleed air circuit in gas turbine plants and related method

    DOEpatents

    Anand, Ashok Kumar; Berrahou, Philip Fadhel; Jandrisevits, Michael

    2003-04-08

    A gas turbine system that includes a compressor, a turbine component and a load, wherein fuel and compressor discharge bleed air are supplied to a combustor and gaseous products of combustion are introduced into the turbine component and subsequently exhausted to atmosphere. A compressor discharge bleed air circuit removes bleed air from the compressor and supplies one portion of the bleed air to the combustor and another portion of the compressor discharge bleed air to an exhaust stack of the turbine component in a single cycle system, or to a heat recovery steam generator in a combined cycle system. In both systems, the bleed air diverted from the combustor may be expanded in an air expander to reduce pressure upstream of the exhaust stack or heat recovery steam generator.

  2. Compressor discharge bleed air circuit in gas turbine plants and related method

    DOEpatents

    Anand, Ashok Kumar; Berrahou, Philip Fadhel; Jandrisevits, Michael

    2002-01-01

    A gas turbine system that includes a compressor, a turbine component and a load, wherein fuel and compressor discharge bleed air are supplied to a combustor and gaseous products of combustion are introduced into the turbine component and subsequently exhausted to atmosphere. A compressor discharge bleed air circuit removes bleed air from the compressor and supplies one portion of the bleed air to the combustor and another portion of the compressor discharge bleed air to an exhaust stack of the turbine component in a single cycle system, or to a heat recovery steam generator in a combined cycle system. In both systems, the bleed air diverted from the combustor may be expanded in an air expander to reduce pressure upstream of the exhaust stack or heat recovery steam generator.

  3. 30 CFR 57.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Compressor discharge pipes. 57.13017 Section 57.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Compressed Air and Boilers § 57.13017 Compressor...

  4. 30 CFR 56.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Compressor discharge pipes. 56.13017 Section 56.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13017 Compressor...

  5. 30 CFR 57.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Compressor discharge pipes. 57.13017 Section 57.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Compressed Air and Boilers § 57.13017 Compressor...

  6. 30 CFR 56.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Compressor discharge pipes. 56.13017 Section 56.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13017 Compressor...

  7. Evaluating susceptibility of compressor oils to autoignition in discharge systems

    SciTech Connect

    Smertyak, Yu.L.; Lukashenko, E.V.; Belous, A.S.

    1986-11-01

    The authors discuss a method developed for evaluating the autoignition tendency of compressor oils which is based on the principle that oil oxidation and autoignition of the products of oil decomposition should be studied under gas-dynamic conditions that approach the conditions actually existing in the discharge systems of high-pressure piston-type air compressors. A diagram of the unit is shown. By means of the test method used here, oils can be classified with respect to their autoignition tendencies in high-pressure systems, particularly in thermally stressed air compressors.

  8. 46 CFR 154.1415 - Air compressor.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Air compressor. 154.1415 Section 154.1415 Shipping COAST... Equipment § 154.1415 Air compressor. Each vessel must have an air compressor to recharge the bottles for the air-breathing apparatus....

  9. 46 CFR 154.1415 - Air compressor.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Air compressor. 154.1415 Section 154.1415 Shipping COAST... Equipment § 154.1415 Air compressor. Each vessel must have an air compressor to recharge the bottles for the air-breathing apparatus....

  10. 46 CFR 154.1415 - Air compressor.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Air compressor. 154.1415 Section 154.1415 Shipping COAST... Equipment § 154.1415 Air compressor. Each vessel must have an air compressor to recharge the bottles for the air-breathing apparatus....

  11. 46 CFR 154.1415 - Air compressor.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Air compressor. 154.1415 Section 154.1415 Shipping COAST... Equipment § 154.1415 Air compressor. Each vessel must have an air compressor to recharge the bottles for the air-breathing apparatus....

  12. 46 CFR 154.1415 - Air compressor.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Air compressor. 154.1415 Section 154.1415 Shipping COAST... Equipment § 154.1415 Air compressor. Each vessel must have an air compressor to recharge the bottles for the air-breathing apparatus....

  13. 23. Station Compressor Room 1 with Air Compressors and Accumulator ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. Station Compressor Room 1 with Air Compressors and Accumulator Tanks, view to the south. One of the two large station air compressor units used for depressing the draft tube water level is visible atop a concrete pedestal on the left side of photograph (the second identical compressor is located in an adjacent room). Two of the six station air accumulator tanks are visible in the background. The smaller station service air compressor is visible in right foreground of the photograph was installed in the early 1980s, and replaced the original station service air compressor. - Washington Water Power Clark Fork River Noxon Rapids Hydroelectric Development, Powerhouse, South bank of Clark Fork River at Noxon Rapids, Noxon, Sanders County, MT

  14. 30 CFR 56.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compressor discharge pipes. 56.13017 Section 56.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Boilers § 56.13017 Compressor discharge pipes. Compressor discharge pipes where carbon build-up may...

  15. 30 CFR 56.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Compressor discharge pipes. 56.13017 Section 56.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Boilers § 56.13017 Compressor discharge pipes. Compressor discharge pipes where carbon build-up may...

  16. 30 CFR 57.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compressor discharge pipes. 57.13017 Section 57.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... and Boilers § 57.13017 Compressor discharge pipes. Compressor discharge pipes where carbon...

  17. 30 CFR 57.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Compressor discharge pipes. 57.13017 Section 57.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... and Boilers § 57.13017 Compressor discharge pipes. Compressor discharge pipes where carbon...

  18. 30 CFR 57.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Compressor discharge pipes. 57.13017 Section 57.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... and Boilers § 57.13017 Compressor discharge pipes. Compressor discharge pipes where carbon...

  19. 30 CFR 56.13017 - Compressor discharge pipes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Compressor discharge pipes. 56.13017 Section 56.13017 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Boilers § 56.13017 Compressor discharge pipes. Compressor discharge pipes where carbon build-up may...

  20. Efficient Vent Unloading of Air Compressors

    NASA Technical Reports Server (NTRS)

    Muhonen, Alvin J.

    1987-01-01

    Method for unloading one-and two-stage reciprocating air compressors increases energy efficiency and inhibits deterioration of components. In new unloader configuration, compressor vented to atmosphere on downstream side. Method implemented expeditiously as modification of existing systems.

  1. 10. Station Air Compressors, view to the north. The compressors, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Station Air Compressors, view to the north. The compressors, visible in the center of the photograph, are linked to the large accumulator tanks visible in the right background of the photograph. Note that part of the compressor in the center foreground of the photograph is disassembled for maintenance. - Washington Water Power Clark Fork River Cabinet Gorge Hydroelectric Development, Powerhouse, North Bank of Clark Fork River at Cabinet Gorge, Cabinet, Bonner County, ID

  2. Positive Displacement Compressor Technology for Air Congitioners

    NASA Astrophysics Data System (ADS)

    Nagatomo, Shigemi

    Trends of compressor technologies for air conditioners are presented in this paper. HFC refrigerants such is R410A and R407C are promising candidates as an alternative for R22. Performance of rotary and scroll compressors in the operation with R410A and R407C are described. In addition, compressor technologies such as efficiency improvement, reliability and simulation methods are described in both cases of rotary and scroll compressors. Advanced compressor technologies developed for air conditioners are desired in the field of the global environment protection and the energy saving.

  3. 30 CFR 57.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Reciprocating-type air compressors. 57.13010... Air and Boilers § 57.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...

  4. 30 CFR 57.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Reciprocating-type air compressors. 57.13010... Air and Boilers § 57.13010 Reciprocating-type air compressors. (a) Reciprocating-type air compressors... than 25 percent. (b) However, this standard does not apply to reciprocating-type air compressors...

  5. 30 CFR 57.13012 - Compressor air intakes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compressor air intakes. 57.13012 Section 57... and Boilers § 57.13012 Compressor air intakes. Compressor air intakes shall be installed to ensure that only clean, uncontaminated air enters the compressors....

  6. 30 CFR 56.13012 - Compressor air intakes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Compressor air intakes. 56.13012 Section 56... Boilers § 56.13012 Compressor air intakes. Compressor air intakes shall be installed to ensure that only clean, uncontaminated air enters the compressors....

  7. 30 CFR 56.13012 - Compressor air intakes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Compressor air intakes. 56.13012 Section 56... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13012 Compressor air intakes. Compressor air intakes shall be installed to ensure that...

  8. 21 CFR 868.6250 - Portable air compressor.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Portable air compressor. 868.6250 Section 868.6250...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6250 Portable air compressor. (a) Identification. A portable air compressor is a device intended to provide compressed air for medical purposes,...

  9. 21 CFR 868.6250 - Portable air compressor.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Portable air compressor. 868.6250 Section 868.6250...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6250 Portable air compressor. (a) Identification. A portable air compressor is a device intended to provide compressed air for medical purposes,...

  10. 30 CFR 57.13012 - Compressor air intakes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Compressor air intakes. 57.13012 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Compressed Air and Boilers § 57.13012 Compressor air intakes. Compressor air intakes shall be installed to...

  11. 30 CFR 56.13012 - Compressor air intakes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Compressor air intakes. 56.13012 Section 56... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13012 Compressor air intakes. Compressor air intakes shall be installed to ensure that...

  12. 21 CFR 868.6250 - Portable air compressor.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Portable air compressor. 868.6250 Section 868.6250...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6250 Portable air compressor. (a) Identification. A portable air compressor is a device intended to provide compressed air for medical purposes,...

  13. 30 CFR 56.13012 - Compressor air intakes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Compressor air intakes. 56.13012 Section 56... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13012 Compressor air intakes. Compressor air intakes shall be installed to ensure that...

  14. 21 CFR 868.6250 - Portable air compressor.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Portable air compressor. 868.6250 Section 868.6250...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Miscellaneous § 868.6250 Portable air compressor. (a) Identification. A portable air compressor is a device intended to provide compressed air for medical purposes,...

  15. 30 CFR 57.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... shall be set or adjusted to the compressor when the normal operating temperature is exceeded by more... over 10 horsepower if equipped with fusible plugs that were installed in the compressor discharge...

  16. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... shall be set or adjusted to the compressor when the normal operating temperature is exceeded by more... over 10 horsepower if equipped with fusible plugs that were installed in the compressor discharge...

  17. 46 CFR 197.310 - Air compressor system.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Air compressor system. 197.310 Section 197.310 Shipping... GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.310 Air compressor system. A compressor used to supply breathing air to a diver must have— (a) A volume tank that is— (1) Built and stamped...

  18. 46 CFR 197.310 - Air compressor system.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Air compressor system. 197.310 Section 197.310 Shipping... GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.310 Air compressor system. A compressor used to supply breathing air to a diver must have— (a) A volume tank that is— (1) Built and stamped...

  19. Electrical discharges in air

    NASA Astrophysics Data System (ADS)

    Antanasijević, R.; Banjanac, R.; Dragić, A.; Joković, D.; Joksimović, D.; Marić, Z.; Panić, B.; Udovičić, V.; Vigier, J. P.

    2002-12-01

    An experiment on electrical discharges in air under normal atmospheric conditions has been performed. The ratio between output and input energy is greater than 1, which confirms the results already reported by Graneau et al.

  20. Noise of a Discharge Check Value Intstalled in a Scroll Compressor with R410A

    NASA Astrophysics Data System (ADS)

    Kim, Youngkey; Kiem, Myungkyun K.; Lee, Dongsoo; Choi, Song; Lee, Byeongchul

    R407C and R410A have been widely used as alternative refrigerants for air conditioners. This paper reports the noise characteristics of a scroll compressor with a discharge check valve when R410A is applied. Since a scroll compressor has a fixed compression ratio, the excessive motion of a check valve occurs under the over compression and under-compression conditions. Moreover, the velocity of the motion is higher in case of using R410A than in case of using R22 or R407C. In this paper, we measured the motion of a check value (a reed valve) by using a gap sensor and also measured the noise of a compressor under various operating conditions. The relationship between the noise and each condition has been investigated. Consequently we have found that we can reduce the noise of a scroll compressor by the optimization of compression ratio.

  1. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Reciprocating-type air compressors. 56.13010... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air...

  2. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Reciprocating-type air compressors. 56.13010... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air...

  3. 30 CFR 56.13010 - Reciprocating-type air compressors.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Reciprocating-type air compressors. 56.13010... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Compressed Air and Boilers § 56.13010 Reciprocating-type air compressors. (a) Reciprocating-type air...

  4. Air Conditioner Compressor Performance Model

    SciTech Connect

    Lu, Ning; Xie, YuLong; Huang, Zhenyu

    2008-09-05

    During the past three years, the Western Electricity Coordinating Council (WECC) Load Modeling Task Force (LMTF) has led the effort to develop the new modeling approach. As part of this effort, the Bonneville Power Administration (BPA), Southern California Edison (SCE), and Electric Power Research Institute (EPRI) Solutions tested 27 residential air-conditioning units to assess their response to delayed voltage recovery transients. After completing these tests, different modeling approaches were proposed, among them a performance modeling approach that proved to be one of the three favored for its simplicity and ability to recreate different SVR events satisfactorily. Funded by the California Energy Commission (CEC) under its load modeling project, researchers at Pacific Northwest National Laboratory (PNNL) led the follow-on task to analyze the motor testing data to derive the parameters needed to develop a performance models for the single-phase air-conditioning (SPAC) unit. To derive the performance model, PNNL researchers first used the motor voltage and frequency ramping test data to obtain the real (P) and reactive (Q) power versus voltage (V) and frequency (f) curves. Then, curve fitting was used to develop the P-V, Q-V, P-f, and Q-f relationships for motor running and stalling states. The resulting performance model ignores the dynamic response of the air-conditioning motor. Because the inertia of the air-conditioning motor is very small (H<0.05), the motor reaches from one steady state to another in a few cycles. So, the performance model is a fair representation of the motor behaviors in both running and stalling states.

  5. Testing of a high performance compressor discharge seal

    NASA Astrophysics Data System (ADS)

    Munson, John H.

    1993-06-01

    A gas lubricated film riding face seal (FRFS) is being developed for use in an advanced subsonic demonstrator engine. This seal will replace the multiple sets of labyrinth seals currently used to seal the compressor discharge air from the engine secondary flow system. The described program consisted of a design, fabrication, and test evaluation phase. This paper deals with testing and results of the rig evaluation of the seals. Several alternative hydrostatic and hydrodynamic FRFS designs were considered in the design phase. Film stiffness, leakage, and heat generation were selected to be the most important design criteria. Using these criteria, hydrodynamic seals proved superior to the hydrostatic designs. Spiral groove design and Rayleigh step pad type seals were selected for detail design and fabrication. Testing was performed in an advanced seal test rig. Both seals were successfully demonstrated. Testing included operation to approximately 700 ft/sec relative velocity, 500 psi pressure differential, and temperatures of at least 1200 F. Noncontacting operation and low leakage rates were demonstrated by both seals.

  6. 46 CFR 197.310 - Air compressor system.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Air compressor system. 197.310 Section 197.310 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE OCCUPATIONAL SAFETY AND HEALTH STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.310 Air compressor system. A...

  7. 46 CFR 197.310 - Air compressor system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Air compressor system. 197.310 Section 197.310 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE OCCUPATIONAL SAFETY AND HEALTH STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.310 Air compressor system. A...

  8. 46 CFR 197.310 - Air compressor system.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Air compressor system. 197.310 Section 197.310 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE OCCUPATIONAL SAFETY AND HEALTH STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.310 Air compressor system. A...

  9. 14. VIEW OF AIR COMPRESSOR. 1500 kw Westinghouse AC generator ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. VIEW OF AIR COMPRESSOR. 1500 kw Westinghouse AC generator steam-turbine unit; beyond is air compressor of Chicago Pneumatic Tool Company, 1920, engineered by Earl E. Know Company, Erie, Pennsylvania. - Juniata Shops, Power Plant & Boiler House, East of Fourth Avenue at Second Street, Altoona, Blair County, PA

  10. 46. Communication equipment room, shock isolator air compressor at right, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    46. Communication equipment room, shock isolator air compressor at right, looking northeast - Ellsworth Air Force Base, Delta Flight, Launch Control Facility, County Road CS23A, North of Exit 127, Interior, Jackson County, SD

  11. Economics of water injected air screw compressor systems

    NASA Astrophysics Data System (ADS)

    Venu Madhav, K.; Kovačević, A.

    2015-08-01

    There is a growing need for compressed air free of entrained oil to be used in industry. In many cases it can be supplied by oil flooded screw compressors with multi stage filtration systems, or by oil free screw compressors. However, if water injected screw compressors can be made to operate reliably, they could be more efficient and therefore cheaper to operate. Unfortunately, to date, such machines have proved to be insufficiently reliable and not cost effective. This paper describes an investigation carried out to determine the current limitations of water injected screw compressor systems and how these could be overcome in the 15-315 kW power range and delivery pressures of 6-10 bar. Modern rotor profiles and approach to sealing and cooling allow reasonably inexpensive air end design. The prototype of the water injected screw compressor air system was built and tested for performance and reliability. The water injected compressor system was compared with the oil injected and oil free compressor systems of the equivalent size including the economic analysis based on the lifecycle costs. Based on the obtained results, it was concluded that water injected screw compressor systems could be designed to deliver clean air free of oil contamination with a better user value proposition than the oil injected or oil free screw compressor systems over the considered range of operations.

  12. Sound reduction of air compressors using a systematic approach

    NASA Astrophysics Data System (ADS)

    Moylan, Justin Tharp

    The noise emitted by portable electric air compressors can often be a nuisance or potentially hazardous to the operator or others nearby. Therefore, reducing the noise of these air compressors is desired. This research focuses on compressors with a reciprocating piston design as this is the most common type of pump design for portable compressors. An experimental setup was developed to measure the sound and vibration of the air compressors, including testing inside a semi-anechoic chamber. The design of a quiet air compressor was performed in four stages: 1) Teardown and benchmarking of air compressors, 2) Identification and isolation of noise sources, 3) Development of individual means to quiet noise sources, 4) Selection and testing of integrated solutions. The systematic approach and results for each of these stages will be discussed. Two redesigned solutions were developed and measured to be approximately 65% quieter than the previous unmodified compressor. An additional analysis was performed on the solutions selected by the participants involved in the selection process. This analysis involved determining which of the design criteria each participant considered most important when selecting solutions. The results from each participant were then compared to their educational background and experience and correlations were identified. The correlations discovered suggest that educational background and experience may be key determinants for the preference models developed.

  13. Study on Variable Capacity Control Mechanism of Scroll Compressor for Automotive Air Conditioner

    NASA Astrophysics Data System (ADS)

    Hirano, Takahisa; Shigeoka, Tetsuo

    As for the automotive air conditioner, (1) to keep the automotive cabin temperature in a comfortable region, (2) to improve driving feeling, (3) to drive the air conditioning system economically through all seasons, are universally required. Recently, from these points, compressors with variable capacity control mechanism for automotive air conditioners have been remarkably requested. We have developed a scroll comoressor with variable capacity control mechanism. The capacity control mechanism, which changes the channel area of the bypass hole continuously, according to the suction gas pressure and the discharge gas pressure, has been developed. In this report, we describe the mechanism of variable capacity control and the performance simulation program that has been developed for the scroll compressor. Further, we describe the measuring results of cylinder pressure behavior, the results of energy loss analysis and the effect of comfort, drivability, power saving in the refrigerating cycle using the developed capacity control compressor.

  14. Compressor-fan unitary structure for air conditioning system

    NASA Astrophysics Data System (ADS)

    Dreiman, N.

    2015-08-01

    An extremely compact, therefore space saving unitary structure of short axial length is produced by radial integration of a revolving piston rotary compressor and an impeller of a centrifugal fan. The unitary structure employs single motor to run as the compressor so the airflow fan and eliminates duality of motors, related power supply and control elements. Novel revolving piston rotary compressor which provides possibility for such integration comprises the following: a suction gas delivery system which provides cooling of the motor and supplies refrigerant into the suction chamber under higher pressure (supercharged); a modified discharge system and lubricating oil supply system. Axial passages formed in the stationary crankshaft are used to supply discharge gas to a condenser, to return vaporized cooling agent from the evaporator to the suction cavity of the compressor, to pass a lubricant and to accommodate wiring supplying power to the unitary structure driver -external rotor electric motor.

  15. View of steam powered air compressor in boiler house. Gas ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of steam powered air compressor in boiler house. Gas engine powered electric generators are visible in far left background. - Burnsville Natural Gas Pumping Station, Saratoga Avenue between Little Kanawha River & C&O Railroad line, Burnsville, Braxton County, WV

  16. Development of High Speed Inverter Rotary Compressor for the Air-conditioning System

    NASA Astrophysics Data System (ADS)

    Kang, Seoung-Min; Yang, Eun-soo; Shin, Jin-Ung; Park, Joon-Hong; Lee, Se-Dong; Ha, Jong-Hun; Son, Young-Boo; Lee, Byeong-Chul

    2015-08-01

    In order to meet the various operating loads of an air-conditioning system, an inverter compressor with a wide operational range is necessary. One of the ways to achieve a wide operation range is to drive a small capacity compressor at high speed. Moreover, it is possible to maximize the efficiency in part-load operation condition close to actual operating conditions and to reduce the cost by compact design of a small capacity compressor. In addition, the shortage of maximum capacity, due to the small rated capacity, is covered through high speed operation. However, in general, if the compressor operates at high speed, problems occurs such as reduced efficiency due to friction, increased noise, increased amount of oil discharge and decreased durability of the main components. In order to solve these problems the following have been investigated: optimized dimension parameters of the compression chamber, enhanced shaft design and the structure for the reduction of oil discharge and noise at high speed operation. Finally the high speed inverter rotary compressor with high efficiency and more compact size has been developed as compared with the conventional rotary compressor.

  17. Integrated turbine-compressor provides air flow for cooling

    NASA Technical Reports Server (NTRS)

    Ferri, A.

    1970-01-01

    Modified supersonic turbine cycle provides cooling air to surrounding structures. Simplified mechanical design assures correct balance of air flow, allows direct issue of cool air to the structure, and assists in matching turbine work output to work input required by the compressor.

  18. New Compressor Added to Glenn's 450- psig Combustion Air System

    NASA Technical Reports Server (NTRS)

    Swan, Jeffrey A.

    2000-01-01

    In September 1999, the Central Process Systems Engineering Branch and the Maintenance and the Central Process Systems Operations Branch, released for service a new high pressure compressor to supplement the 450-psig Combustion Air System at the NASA Glenn Research Center at Lewis Field. The new compressor, designated C-18, is located in Glenn s Central Air Equipment Building and is remotely operated from the Central Control Building. C-18 can provide 40 pounds per second (pps) of airflow at pressure to our research customers. This capability augments our existing system capacity (compressors C 4 at 38 pps and C-5 at 32 pps), which is generated from Glenn's Engine Research Building. The C-18 compressor was originally part of Glenn's 21-Inch Hypersonic Tunnel, which was transferred from the Jet Propulsion Laboratory to Glenn in the mid-1980's. With the investment of construction of facilities funding, the compressor was modified, new mechanical and electrical support equipment were purchased, and the unit was installed in the basement of the Central Air Equipment Building. After several weeks of checkout and troubleshooting, the new compressor was ready for long-term, reliable operations. With a total of 110 pps in airflow now available, Glenn is well positioned to support the high-pressure air test requirements of our research customers.

  19. 7. Air Blast Circuit Breaker Compressors, view to the southeast. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Air Blast Circuit Breaker Compressors, view to the southeast. The air blast circuit breakers are visible in the left background of the photograph. - Washington Water Power Clark Fork River Noxon Rapids Hydroelectric Development, Powerhouse, South bank of Clark Fork River at Noxon Rapids, Noxon, Sanders County, MT

  20. 15. BASE OF MST, SOUTHEAST SIDE, FACING SOUTHWEST. AIR COMPRESSOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. BASE OF MST, SOUTHEAST SIDE, FACING SOUTHWEST. AIR COMPRESSOR SHED AT STATION 3; PLATFORM AT STATION 12; ENVIRONMENTAL CURTAIN SWING AT STATION 21. ELECTRICAL HOOKUPS ON RIGHT SIDE OF PHOTOGRAPH. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  1. Centrifugal Compressor Surge Margin Improved With Diffuser Hub Surface Air Injection

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.

    2002-01-01

    Aerodynamic stability is an important parameter in the design of compressors for aircraft gas turbine engines. Compression system instabilities can cause compressor surge, which may lead to the loss of an aircraft. As a result, engine designers include a margin of safety between the operating line of the engine and the stability limit line of the compressor. The margin of safety is typically referred to as "surge margin." Achieving the highest possible level of surge margin while meeting design point performance objectives is the goal of the compressor designer. However, performance goals often must be compromised in order to achieve adequate levels of surge margin. Techniques to improve surge margin will permit more aggressive compressor designs. Centrifugal compressor surge margin improvement was demonstrated at the NASA Glenn Research Center by injecting air into the vaned diffuser of a 4:1-pressure-ratio centrifugal compressor. Tests were performed using injector nozzles located on the diffuser hub surface of a vane-island diffuser in the vaneless region between the impeller trailing edge and the diffuser-vane leading edge. The nozzle flow path and discharge shape were designed to produce an air stream that remained tangent to the hub surface as it traveled into the diffuser passage. Injector nozzles were located near the leading edge of 23 of the 24 diffuser vanes. One passage did not contain an injector so that instrumentation located in that passage would be preserved. Several orientations of the injected stream relative to the diffuser vane leading edge were tested over a range of injected flow rates. Only steady flow (nonpulsed) air injection was tested. At 100 percent of the design speed, a 15-percent improvement in the baseline surge margin was achieved with a nozzle orientation that produced a jet that was bisected by the diffuser vane leading edge. Other orientations also improved the baseline surge margin. Tests were conducted at speeds below the

  2. Turbine inter-disk cavity cooling air compressor

    DOEpatents

    Chupp, Raymond E.; Little, David A.

    1998-01-01

    The inter-disk cavity between turbine rotor disks is used to pressurize cooling air. A plurality of ridges extend radially outwardly over the face of the rotor disks. When the rotor disks are rotated, the ridges cause the inter-disk cavity to compress air coolant flowing through the inter-disk cavity en route to the rotor blades. The ridges eliminate the need for an external compressor to pressurize the air coolant.

  3. Turbine inter-disk cavity cooling air compressor

    DOEpatents

    Chupp, R.E.; Little, D.A.

    1998-01-06

    The inter-disk cavity between turbine rotor disks is used to pressurize cooling air. A plurality of ridges extend radially outwardly over the face of the rotor disks. When the rotor disks are rotated, the ridges cause the inter-disk cavity to compress air coolant flowing through the inter-disk cavity en route to the rotor blades. The ridges eliminate the need for an external compressor to pressurize the air coolant. 5 figs.

  4. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors § 204.52 Portable air compressor...

  5. Stationary Engineers Apprenticeship. Related Training Modules. 19.1-19.2 Air Compressors.

    ERIC Educational Resources Information Center

    Lane Community Coll., Eugene, OR.

    This learning module, one in a series of 20 related training modules for apprentice stationary engineers, deals with air compressors. Addressed in the individual instructional packages included in the module are types of air compressors and the maintenance and operation of air compressors. Each instructional package in the module contains some or…

  6. 66. VIEW, LOOKING EAST, OF AIR COMPRESSOR LOCATED IN CONDENSER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. VIEW, LOOKING EAST, OF AIR COMPRESSOR LOCATED IN CONDENSER GALLERY BELOW TURBINE HALL. THIS UNIT WAS POWERED BY A RECIPROCATING STEAM ENGINE AND WAS PART OF THE ORIGINAL PLANT MACHINERY. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

  7. 21 CFR 868.6250 - Portable air compressor.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Portable air compressor. 868.6250 Section 868.6250 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....g., to drive ventilators and other respiratory devices. (b) Classification. Class II...

  8. Centrifugal compressors for automotive air conditioners -- Component design

    SciTech Connect

    Yun, H.; Smith, J.L. Jr.

    1996-12-31

    The application of a novel, electric motor-driven, variable-speed centrifugal compressor for automotive air conditioners has been investigated. For the feasibility analysis, a configuration design has been performed. It includes refrigerant selection, thermodynamic cycle analysis, compressor aerodynamic design, and mechanical layout of the integrated motor-compressor structure. Both the motor constraints (provided by the Laboratory for Electromagnetic and Electronic Systems at M.I.T.) and the compressor constraints were considered for the configuration design. The result is an inter-cooled two-stage compression system using R123 as the refrigerant. The inter-cooling is achieved by feeding back a small fraction of the condenser liquid into the return channel between the first and the second stage through the electric motor. At the design condition, the pressure ratio is 3.2 for the first stage and 1.9 for the second stage. The design rotational speed is 75,000 rpm, and the maximum cooling capacity is 5,275 Watts. High efficiency is expected by varying the compressor speed to match the required cooling load at each instant.

  9. R-189 (C-620) air compressor control logic software documentation. Revision 1

    SciTech Connect

    Walter, K.E.

    1995-06-08

    This relates to FFTF plant air compressors. Purpose of this document is to provide an updated Computer Software Description for the software to be used on R-189 (C-620-C) air compressor programmable controllers. Logic software design changes were required to allow automatic starting of a compressor that had not been previously started.

  10. High Technology Centrifugal Compressor for Commercial Air Conditioning Systems

    SciTech Connect

    Ruckes, John

    2006-04-15

    R&D Dynamics, Bloomfield, CT in partnership with the State of Connecticut has been developing a high technology, oil-free, energy-efficient centrifugal compressor called CENVA for commercial air conditioning systems under a program funded by the US Department of Energy. The CENVA compressor applies the foil bearing technology used in all modern aircraft, civil and military, air conditioning systems. The CENVA compressor will enhance the efficiency of water and air cooled chillers, packaged roof top units, and other air conditioning systems by providing an 18% reduction in energy consumption in the unit capacity range of 25 to 350 tons of refrigeration The technical approach for CENVA involved the design and development of a high-speed, oil-free foil gas bearing-supported two-stage centrifugal compressor, CENVA encompassed the following high technologies, which are not currently utilized in commercial air conditioning systems: Foil gas bearings operating in HFC-134a; Efficient centrifugal impellers and diffusers; High speed motors and drives; and System integration of above technologies. Extensive design, development and testing efforts were carried out. Significant accomplishments achieved under this program are: (1) A total of 26 builds and over 200 tests were successfully completed with successively improved designs; (2) Use of foil gas bearings in refrigerant R134a was successfully proven; (3) A high speed, high power permanent magnet motor was developed; (4) An encoder was used for signal feedback between motor and controller. Due to temperature limitations of the encoder, the compressor could not operate at higher speed and in turn at higher pressure. In order to alleviate this problem a unique sensorless controller was developed; (5) This controller has successfully been tested as stand alone; however, it has not yet been integrated and tested as a system; (6) The compressor successfully operated at water cooled condensing temperatures Due to temperature

  11. Methodology for the determination of criticality codes and recertification intervals for Tank Mounted Air Compressors (TMAC) and Base Mounted Air Compressors (BMAC)

    NASA Technical Reports Server (NTRS)

    Hargrove, William T.

    1991-01-01

    This methodology is used to determine inspection procedures and intervals for components contained within tank mounted air compressor systems (TMAC) and base mounted air compressor systems (BMAC). These systems are included in the Pressure Vessel and System Recertification inventory at GSFC.

  12. Relative performance comparison between baseline labyrinth and dual-brush compressor discharge seals in a T-700 engine test

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.; Griffin, Thomas A.; Csavina, Kristine R.; Pancholi, Arvind; Sood, Dvandra

    1994-01-01

    In separate series of T-700 engine tests, direct comparisons were made between the forward-facing labyrinth and dual-brush compressor discharge seals. Compressor speeds to 43,000 rpm, surface speeds to 160 m/s (530 ft/s), pressures to 1 MPa (145 psi), and temperatures to 680 K (765 F) characterized these tests. The wear estimate for 40 hr of engine operations was less than 0.025 mm (0.001 in.) of the Haynes 25 alloy bristles running against a chromium-oxide-coated rub runner. The pressure drops were higher for the dual-brush than for the forward-facing labyrinth seal, implying better seal characteristics and engine performance for the brush seal. Modification of the secondary flow path requires that changes in cooling air and engine dynamics be accounted for.

  13. Relative performance comparison between baseline labyrinth and dual-brush compressor discharge seals in a T-700 engine test

    NASA Astrophysics Data System (ADS)

    Hendricks, Robert C.; Griffin, Thomas A.; Csavina, Kristine R.; Pancholi, Arvind; Sood, Dvandra

    1994-07-01

    In separate series of T-700 engine tests, direct comparisons were made between the forward-facing labyrinth and dual-brush compressor discharge seals. Compressor speeds to 43,000 rpm, surface speeds to 160 m/s (530 ft/s), pressures to 1 MPa (145 psi), and temperatures to 680 K (765 F) characterized these tests. The wear estimate for 40 hr of engine operations was less than 0.025 mm (0.001 in.) of the Haynes 25 alloy bristles running against a chromium-oxide-coated rub runner. The pressure drops were higher for the dual-brush than for the forward-facing labyrinth seal, implying better seal characteristics and engine performance for the brush seal. Modification of the secondary flow path requires that changes in cooling air and engine dynamics be accounted for.

  14. Impact of the electric compressor for automotive air conditioning system on fuel consumption and performance analysis

    NASA Astrophysics Data System (ADS)

    Zulkifli, A. A.; Dahlan, A. A.; Zulkifli, A. H.; Nasution, H.; Aziz, A. A.; Perang, M. R. M.; Jamil, H. M.; Misseri, M. N.

    2015-12-01

    Air conditioning system is the biggest auxiliary load in a vehicle where the compressor consumed the largest. Problem with conventional compressor is the cooling capacity cannot be control directly to fulfill the demand of thermal load inside vehicle cabin. This study is conducted experimentally to analyze the difference of fuel usage and air conditioning performance between conventional compressor and electric compressor of the air conditioning system in automobile. The electric compressor is powered by the car battery in non-electric vehicle which the alternator will recharge the battery. The car is setup on a roller dynamometer and the vehicle speed is varied at 0, 30, 60, 90 and 110 km/h at cabin temperature of 25°C and internal heat load of 100 and 400 Watt. The results shows electric compressor has better fuel consumption and coefficient of performance compared to the conventional compressor.

  15. 46 CFR 35.35-85 - Air compressors-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Air compressors-TB/ALL. 35.35-85 Section 35.35-85 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-85 Air compressors—TB/ALL. No person may operate, install, or reinstall an air compressor in a cargo area...

  16. 46 CFR 35.35-85 - Air compressors-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Air compressors-TB/ALL. 35.35-85 Section 35.35-85 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-85 Air compressors—TB/ALL. No person may operate, install, or reinstall an air compressor in a cargo area...

  17. 46 CFR 35.35-85 - Air compressors-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Air compressors-TB/ALL. 35.35-85 Section 35.35-85 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-85 Air compressors—TB/ALL. No person may operate, install, or reinstall an air compressor in a cargo area...

  18. 46 CFR 35.35-85 - Air compressors-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Air compressors-TB/ALL. 35.35-85 Section 35.35-85 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-85 Air compressors—TB/ALL. No person may operate, install, or reinstall an air compressor in a cargo area...

  19. 46 CFR 35.35-85 - Air compressors-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Air compressors-TB/ALL. 35.35-85 Section 35.35-85 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS Cargo Handling § 35.35-85 Air compressors—TB/ALL. No person may operate, install, or reinstall an air compressor in a cargo area...

  20. Analytical and Experimental Investigation of the Effects of Compressor Interstage Air Bleed on Performance Characteristics of a 13-stage Axial-flow Compressor

    NASA Technical Reports Server (NTRS)

    Lucas, James G; Geye, Richard P; Calvert, Howard F

    1957-01-01

    Air was bled over the fifth-and tenth-stage rotor-blade rows through ports designed to pass 11 and 9 percent of the inlet flow, respectively, at 80 percent speed. Along the rated operating line the maximum speed at which rotating stall was encountered was lowered by either of these bleeds, and the stall patterns below these speeds were altered so that no dangerous resonant rotor-blade bending vibrations were excited. The combination of the two bleeds completely eliminated rotating stall to at least 50 percent speed. The compressor-discharge weight flow was decreased only at intermediate speeds, and the overall pressure ratio was affected only at intermediate speeds, and the overall pressure ratio was affected only by the combination bleed at intermediate speeds. Fifth-stage bleed increased compressor efficiency at low speeds, and tenth-stage bleed decreased efficiency at intermediate speeds.

  1. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors §...

  2. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors §...

  3. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors §...

  4. 40 CFR 204.52 - Portable air compressor noise emission standard.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Portable air compressor noise emission standard. 204.52 Section 204.52 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors §...

  5. Numerical Investigation of Flow Losses through Discharge Line of Household Type Refrigerator Compressors

    NASA Astrophysics Data System (ADS)

    Yesilaydin, I.; Erbay, L. B.

    2015-08-01

    The technological developments, competition and energy policies are forcing the refrigeration market to increase the efficiency of their products as never before. The component that determines the performance and efficiency of the refrigeration system is the compressor, which is the major energy consumer in a compression refrigeration system. One of the essential elements of the total compressor efficiency is the discharge line flow efficiency that is subjected to this study. In this paper, the effects of design parameters on flow loses at discharge line of a hermetic reciprocating compressor were investigated with numerical flow analysis. At this study, three conceptual designs were modelled based on the discharge line design parameters such as line diameter, resonator volumes and line length. The pressure drop regions are determined by CFD analyses and they compared against the base model. Analyses are carried out by using commercial CFD software. Furthermore, the obtained numerical results were compared to experimental data and presented a good agreement in terms of pressure drop and discharge line flow efficiency.

  6. 241-U-701 new compressor building and instrument air piping analyses

    SciTech Connect

    Huang, F.H.

    1994-08-25

    Building anchorage analysis is performed to qualify the design of the new compressor building foundation given in the ECN ``241-U-701 New Compressor Building.`` Recommendations for some changes in the ECN are made accordingly. Calculations show that the 6-in.-slab is capable of supporting the pipe supports, and that the building foundation, air compressor and dryer anchorage, and electric rack are adequate structurally. Analysis also shows that the instrument air piping and pipe supports for the compressed air system meet the applicable code requirements and are acceptable. The building is for the U-Farm instrument air systems.

  7. Low-friction coatings for air bearings in fuel cell air compressors

    SciTech Connect

    Ajayi, O. O.; Fenske, G. R.; Erdemir, A.; Woodford, J.; Sitts, J.; Elshot, K.; Griffey, K.

    2000-01-06

    In an effort to reduce fuel consumption and emissions, hybrid vehicles incorporating fuel cell systems are being developed by automotive manufacturers, their suppliers, federal agencies (specifically, the US Department of Energy) and national laboratories. The fuel cell system will require an air management subsystem that includes a compressor/expander. Certain components in the compressor will require innovative lubrication technology in order to reduce parasitic energy losses and improve their reliability and durability. One such component is the air bearing for air turbocompressors designed and fabricated by Meruit, Inc. Argonne National Laboratory recently developed a carbon-based coating with low friction and wear attributes; this near-frictionless-carbon (NFC) coating is a potential candidate for use in turbocompressor air bearings. The authors present here an evaluation of the Argonne coating for air compressor thrust bearings. With two parallel 440C stainless steel discs in unidirectional sliding contact, the NFC reduced the frictional force four times and the wear rate by more than two orders of magnitude. Wear mechanism on the uncoated surface involved oxidation and production of iron oxide debris. Wear occurred on the coated surfaces primarily by a polishing mechanism.

  8. DEVELOPMENT OF A LINEAR COMPRESSOR FOR AIR CONDITIONERS AND HEAT PUMPS

    EPA Science Inventory

    The report discusses the design, building, testing, and delivering to the Environmental Protection Agency of a linear compressor for operation in a 3.0- ton (10.5 kW) residential air-conditioning and heat pumping system. The compressor design evolved from a linear resonant piston...

  9. Relative performance comparison between baseline labyrinth and dual-brush compressor discharge seals in a T-700 engine test

    NASA Technical Reports Server (NTRS)

    Hendricks, Robert C.; Griffin, Thomas A.; Kline, Teresa R.; Csavina, Kristine R.; Pancholi, Arvind; Sood, Devendra

    1995-01-01

    In separate series of YT-700 engine tests, direct comparisons were made between the forward-facing labyrinth and dual brush compressor discharge seals. Compressor speeds to 43 000 rpm, surface speeds to 160 m/s (530 ft/s), pressures to 1 MPa (145 psi), and temperatures to 680 K (765 F) characterized these tests. The wear estimate for 46 hr of engine operations was less than 0.025 mm (0.001 in.) of the Haynes 25 alloy bristles running against a chromium-carbide-coated rub runner. The pressure drops were higher for the dual-brush seal than for the forward-facing labyrinth seal and leakage was lower-with the labyrinth seal leakage being 2-1/2 times greater-implying better seal characteristics, better secondary airflow distribution, and better engine performance (3 percent at high pressure to 5 percent at lower pressure) for the brush seal. (However, as brush seals wear down (after 500 to 1000 hr of engine operation), their leakage rates will increase.) Modification of the secondary flow path requires that changes in cooling air and engine dynamics be accounted for.

  10. Relative performance comparison between baseline labyrinth and dual-brush compressor discharge seals in a T-700 engine test

    NASA Astrophysics Data System (ADS)

    Hendricks, Robert C.; Griffin, Thomas A.; Kline, Teresa R.; Csavina, Kristine R.; Pancholi, Arvind; Sood, Devendra

    1995-10-01

    In separate series of YT-700 engine tests, direct comparisons were made between the forward-facing labyrinth and dual brush compressor discharge seals. Compressor speeds to 43 000 rpm, surface speeds to 160 m/s (530 ft/s), pressures to 1 MPa (145 psi), and temperatures to 680 K (765 F) characterized these tests. The wear estimate for 46 hr of engine operations was less than 0.025 mm (0.001 in.) of the Haynes 25 alloy bristles running against a chromium-carbide-coated rub runner. The pressure drops were higher for the dual-brush seal than for the forward-facing labyrinth seal and leakage was lower-with the labyrinth seal leakage being 2-1/2 times greater-implying better seal characteristics, better secondary airflow distribution, and better engine performance (3 percent at high pressure to 5 percent at lower pressure) for the brush seal. (However, as brush seals wear down (after 500 to 1000 hr of engine operation), their leakage rates will increase.) Modification of the secondary flow path requires that changes in cooling air and engine dynamics be accounted for.

  11. Study of noise transmission from an air compressor

    NASA Astrophysics Data System (ADS)

    Nathak, Subhro; Puranik, Anand; Schut, Jeffrey; Wells, Lee; Rao, M. D.

    2005-09-01

    The paper discusses the reduction of noise from a Porter Cable 4-gal, 135-psi air compressor. The objectives were to identify the major sources of noise, implement possible noise control measures, and evaluate their effectiveness. Sound measurements were taken according to a procedure that was developed and based on the standards for power tools. Broadband analysis (1/12 octave band) was done to determine the main sources of noise. Ranking of noise sources was done accordingly. The major source of noise was determined to be the piston cylinder assembly and efforts were taken to reduce this main source of noise. The noise control treatments included manufacturing of new parts, use of gasket made of cork between the housing and the cylinder sleeve to isolate the vibrations, implementing a silencer at the exhaust side of the piston and finally, an enclosure encircling the piston/cylinder assembly. The sound-pressure level measurements of the prototype were compared to the baseline measurements to test the effectiveness of the treatments. The overall sound pressure level was reduced from 101.5 to 94.3 dB with the implementation of enclosure around the piston/cylinder assembly and the silencer at the exhaust side of the piston.

  12. Self-energized plasma compressor. [for compressing plasma discharged from coaxial plasma generator

    NASA Technical Reports Server (NTRS)

    Shriver, E. L.; Igenbergs, E. B. (Inventor)

    1974-01-01

    The self-energized plasma compressor is described which compresses plasma discharged from a coaxial plasma generator. The device includes a helically shaped coil which is coaxially aligned with the center axis of the coaxial plasma generator. The plasma generator creates a current through the helical coil which, in turn, generates a time varying magnetic field that creates a force which acts radially upon the plasma. The coaxial plasma generator and helical coil move the plasma under high pressure and temperature to the narrow end of the coil. Positioned adjacent to the narrow end of the coil are beads which are engaged by the plasma to be accelerated to hypervelocities for simulating meteoroids.

  13. Centrifugal compressors for automotive air conditioners -- System design and operation strategy

    SciTech Connect

    Yun, H.; Smith, J.L. Jr.

    1996-12-31

    System designs and operation strategies for a motor-driven, variable-speed compression system (described in the companion paper) have been developed. Systems which can cover the required range of operating conditions (i.e., various cooling loads) have been designed. They require a compromise between high efficiency at high cooling loads and compressor surge prevention at low cooling loads. Therefore, compressor operation strategies consist of a variable speed strategy for stable operating points (to match the cooling load at any instant) and a compressor stabilization strategy (to prevent compressor surge instability at low cooling load operations) for unstable operating points. The system design and the operation strategy study results indicate that the novel compression device can improve the overall system efficiency by matching the compressor characteristics with the rest of the air conditioning system.

  14. Mid-section of a can-annular gas turbine engine with an improved rotation of air flow from the compressor to the turbine

    DOEpatents

    Little, David A.; Schilp, Reinhard; Ross, Christopher W.

    2016-03-22

    A midframe portion (313) of a gas turbine engine (310) is presented and includes a compressor section with a last stage blade to orient an air flow (311) at a first angle (372). The midframe portion (313) further includes a turbine section with a first stage blade to receive the air flow (311) oriented at a second angle (374). The midframe portion (313) further includes a manifold (314) to directly couple the air flow (311) from the compressor section to a combustor head (318) upstream of the turbine section. The combustor head (318) introduces an offset angle in the air flow (311) from the first angle (372) to the second angle (374) to discharge the air flow (311) from the combustor head (318) at the second angle (374). While introducing the offset angle, the combustor head (318) at least maintains or augments the first angle (372).

  15. Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

    SciTech Connect

    Shlapakovski, A. S.; Beilin, L.; Krasik, Ya. E.; Hadas, Y.; Schamiloglu, E.

    2015-07-15

    Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

  16. Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

    NASA Astrophysics Data System (ADS)

    Shlapakovski, A. S.; Beilin, L.; Hadas, Y.; Schamiloglu, E.; Krasik, Ya. E.

    2015-07-01

    Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

  17. Air-Cooled Design of a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization Systems

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.; Affleck, Dave L.; Rosen, Micha; LeVan, M. Douglas; Wang, Yuan; Cavalcante, Celio L.

    2004-01-01

    The air revitalization system of the International Space Station (ISS) operates in an open loop mode and relies on the resupply of oxygen and other consumables from earth for the life support of astronauts. A compressor is required for delivering the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and thereby closing the air-loop. We have a developed a temperature-swing adsorption compressor (TSAC) for performing these tasks that is energy efficient, quiet, and has no rapidly moving parts. This paper discusses the mechanical design and the results of thermal model validation tests of a TSAC that uses air as the cooling medium.

  18. Effect of double air injection on performance characteristics of centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Hirano, Toshiyuki; Takano, Mizuki; Tsujita, Hoshio

    2015-02-01

    In the operation of a centrifugal compressor of turbocharger, instability phenomena such as rotating stall and surge are induced at a lower flow rate close to the maximum pressure ratio. In this study, for the suppression of surge phenomenon resulting in the extension of the stable operating range of centrifugal compressor to lower flow rate, the compressed air at the compressor exit was re-circulated and injected into the impeller inlet by using the double injection nozzle system. The experiments were performed to find out the optimum circumferential position of the second nozzle relative to the fixed first one and the optimum inner diameter of the injection nozzles, which are able to most effectively reduce the flow rate of surge inception. Moreover, in order to examine the universality of these optimum values, the experiments were carried out for two types of compressors.

  19. Interaction of temperature, humidity, driver preferences, and refrigerant type on air conditioning compressor usage.

    PubMed

    Levine, C; Younglove, T; Barth, M

    2000-10-01

    Recent studies have shown large increases in vehicle emissions when the air conditioner (AC) compressor is engaged. Factors that affect the compressor-on percentage can have a significant impact on vehicle emissions and can also lead to prediction errors in current emissions models if not accounted for properly. During 1996 and 1997, the University of California, Riverside, College of Engineering-Center for Environmental Research and Technology (CE-CERT) conducted a vehicle activity study for the California Air Resources Board (CARB) in the Sacramento, CA, region. The vehicles were randomly selected from all registered vehicles in the region. As part of this study, ten vehicles were instrumented to collect AC compressor on/off data on a second-by-second basis in the summer of 1997. Temperature and humidity data were obtained and averaged on an hourly basis. The ten drivers were asked to complete a short survey about AC operational preferences. This paper examines the effects of temperature, humidity, refrigerant type, and driver preferences on air conditioning compressor activity. Overall, AC was in use in 69.1% of the trips monitored. The compressor was on an average of 64% of the time during the trips. The personal preference settings had a significant effect on the AC compressor-on percentage but did not interact with temperature. The refrigerant types, however, exhibited a differential response across temperature, which may necessitate separate modeling of the R12 refrigerant-equipped vehicles from the R134A-equipped vehicles. It should be noted that some older vehicles do get retrofitted with new compressors that use R134A; however, none of the vehicles in this study had been retrofitted. PMID:11288304

  20. Turbine inter-disk cavity cooling air compressor

    DOEpatents

    Little, David Allen

    2001-01-01

    A combustion turbine may have a cooling circuit for directing a cooling medium through the combustion turbine to cool various components of the combustion turbine. This cooling circuit may include a compressor, a combustor shell and a component of the combustion turbine to be cooled. This component may be a rotating blade of the combustion turbine. A pressure changing mechanism is disposed in the combustion turbine between the component to be cooled and the combustor shell. The cooling medium preferably flows from the compressor to the combustor shell, through a cooler, the component to the cooled and the pressure changing mechanism. After flowing through the pressure changing mechanism, the cooling medium is returned to the combustor shell. The pressure changing mechanism preferably changes the pressure of the cooling medium from a pressure at which it is exhausted from the component to be cooled to approximately that of the combustor shell.

  1. Runaway electrons from laboratory discharges in air

    NASA Astrophysics Data System (ADS)

    Montanya, J.; March, V.

    2011-12-01

    The role of runaway electrons in the lightning discharge it is still unknown. High energy electrons are associated with lightning discharges and occur with electric field variations associated with leader lightning advancement. On the other hand, Terrestrial Gamma-ray Flashes (TGF) are bursts of high energetic particles from the earth. TGF have been associated with lightning, but its origin is still under debate. In 2005 it was demonstrated that runaway electrons appear during high voltage impulses in the laboratory. These results opened the research of high energy particles in the laboratory and some researchers have focused its research in this field. From 2010 we have conducted different experiments using a Marx generator. We created impulse voltages up to 1 MV for air gaps between 30 and 100 cm. Shielded NaI(Tl) detectors were used to measure high energy particles from the discharge. We have designed experiments in order to discover the properties of these runaway electrons. From more than 2000 sparks, we showed that runaway electrons are affected by the rise time of the impulse, presented the role of each electrode in the acceleration of electrons and the role of the electric field in the process. In this presentation, we focus on the results of laboratory discharges and the possible implications in lightning discharges and TGF. The controlled impulse voltages in the laboratory can constitute an indirect way for study this phenomenon.

  2. Reliability and Maintainability Analysis of a High Air Pressure Compressor Facility

    NASA Technical Reports Server (NTRS)

    Safie, Fayssal M.; Ring, Robert W.; Cole, Stuart K.

    2013-01-01

    This paper discusses a Reliability, Availability, and Maintainability (RAM) independent assessment conducted to support the refurbishment of the Compressor Station at the NASA Langley Research Center (LaRC). The paper discusses the methodologies used by the assessment team to derive the repair by replacement (RR) strategies to improve the reliability and availability of the Compressor Station (Ref.1). This includes a RAPTOR simulation model that was used to generate the statistical data analysis needed to derive a 15-year investment plan to support the refurbishment of the facility. To summarize, study results clearly indicate that the air compressors are well past their design life. The major failures of Compressors indicate that significant latent failure causes are present. Given the occurrence of these high-cost failures following compressor overhauls, future major failures should be anticipated if compressors are not replaced. Given the results from the RR analysis, the study team recommended a compressor replacement strategy. Based on the data analysis, the RR strategy will lead to sustainable operations through significant improvements in reliability, availability, and the probability of meeting the air demand with acceptable investment cost that should translate, in the long run, into major cost savings. For example, the probability of meeting air demand improved from 79.7 percent for the Base Case to 97.3 percent. Expressed in terms of a reduction in the probability of failing to meet demand (1 in 5 days to 1 in 37 days), the improvement is about 700 percent. Similarly, compressor replacement improved the operational availability of the facility from 97.5 percent to 99.8 percent. Expressed in terms of a reduction in system unavailability (1 in 40 to 1 in 500), the improvement is better than 1000 percent (an order of magnitude improvement). It is worthy to note that the methodologies, tools, and techniques used in the LaRC study can be used to evaluate

  3. Millwright Apprenticeship. Related Training Modules. 13.1-13.2 Air Compressors.

    ERIC Educational Resources Information Center

    Lane Community Coll., Eugene, OR.

    This packet of two learning modules on air compressors is one of six such packets developed for apprenticeship training for millwrights. Introductory materials are a complete listing of all available modules and a supplementary reference list. Each module contains some or all of these components: goal, performance indicators, study guide (a check…

  4. 68. Interior view in pit "B" showing air compressor/purifier on ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    68. Interior view in pit "B" showing air compressor/purifier on left, and entry door to pit in center, with fallout shelter/escapr route on right, looking east - Nike Missile Battery MS-40, County Road No. 260, Farmington, Dakota County, MN

  5. Study on Improvement of the Suction Valve in a Reciprocating Compressor for an Automotive Air-Conditioner

    NASA Astrophysics Data System (ADS)

    Koyabu, Eitaro; Tsukiji, Tetsuhiro; Matsumura, Yoshito; Sato, Taizo

    The simplified test model of the commercial reciprocating compressor for an automotive air-conditioner, which is developed in the previous study, is used to measure the displacement of the suction valves using as train gauge and to investigate the velocity distributions of the discharge flow from the valves using PIV (Particle Image Velocimetry) technique. This paper is focused on the effects of shape of the suction valve on the vibration-reduction. First, the size of the conventional valve hole and the width of the tip of the conventional valve are changed and seven new valves are manufactured to reduce the vibration of the valve. Consequently, it is found that one of the new valves is the most effective for the vibration-reduction. Next the influence of the natural frequency on the vibration-reduction is investigated using one of the new valves by changing the material and the thickness of the valve. Finally, the reason of the vibration-reduction for one of the new valves is discussed from the results of the flow analysis around the valve. The vibration-reduction for one of the new valves is confirmed by measurement of the displacement of the valve in the reciprocating compressor for the automotive air-conditioner.

  6. Experimental Study on Efficiency Improvement of R410A Scroll Compressor for Air Conditioner

    NASA Astrophysics Data System (ADS)

    Sawai, Kiyoshi; Sakuda, Atsushi; Iida, Noboru; Hiwata, Akira; Morimoto, Takashi; Ishii, Noriaki

    In scroll compressors, an increase in oil flow rate into thecompression chamber improves sealing effectsand decreases refrigerant leakage. On the other hand, as the oil supplies the heat energy, the suction refrigerantis heated and the volumetric efficiency degreases. In the present study, we made an apparatus which suppliesthe oil into the compression chamber while measuring the mass flow rate, thus investigating the relationshipbetween the oil flow rate and the compressor performance. Experimental results indicated that the presentR410A scroll compressor provided higher performance as the oil flow rate decreased under the rated conditionof the air-conditioner. In addition, based on the experimental results, we discussed that the oil flow in thecapillary installed in the orbiting scroll was considered to be a laminar flow, and the volumetric efficiencywould degrease by the effect of a quarter of the oil heat energy.

  7. R-1 (C-620-A) and R-2 (C-620-B) air compressor control logic, computer software description. Revision 1

    SciTech Connect

    Walter, K.E.

    1995-06-08

    This document provides an updated computer software description for the software used on the FFTF R-1 (C-620-A) and R-2 (C-620-B) air compressor programmable controllers. Logic software design changes were required to allow automatic starting of a compressor that had not been previously started.

  8. Model analysis and nonlinear control of air compressors

    NASA Astrophysics Data System (ADS)

    Sari, Gholam-Reza

    For decades, gas turbines have been important, widespread, and reliable devices in the field of power generation, petrochemical industry, and aeronautics. They employ centrifugal and axial compressors which suffer from aerodynamic instabilities, namely, surge and rotating stall. These performance limiting instabilities can cause component stress, lifespan reduction, noise, and vibration. Furthermore, in variable speed axial compressors (VSACs), speed variations affect the system stability and can lead to surge and rotating stall. This limits the rate of speed variations and results in important performance penalties. The present work firstly addresses the bifurcation analysis of VSACs' model to investigate the impact of speed dynamics on the stability of efficient operating points. Here, the rate of speed variations (acceleration rate) is defined as a new parameter of the model and a detailed numerical bifurcation analysis is provided. The results of time-domain simulations not only validate the results of bifurcation analysis, but also broaden our knowledge about the transient response of the model, which is a matter of importance as well. The analysis reveals that speed variations can lead to a fully developed rotating stall as well as the previously reported temporary stall developments. The results show that the developed instabilities depend to a great extent on the acceleration rate. The impact of other key issues such as throttle gain, viscosity factor, initial speed, final speed, and the contribution of stall modes are also explored. From the control point of view, despite reported achievements, robust control design for compression systems remains a challenging problem. In this work, at first, two nonlinear approaches are proposed to tackle the stability problem of constant-speed axial compressors (CSACs). The first approach is a robust passivity-based control and the second one is a second order sliding mode control. The approaches tackle the challenging

  9. 111. AIR CONDENSATE PUMP. NOTE MAIN DISCHARGE HEADER ABOVE STEAMEND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    111. AIR CONDENSATE PUMP. NOTE MAIN DISCHARGE HEADER ABOVE STEAM-END CYLINDER. NOTE ALSO, THE 30' DISCHARGE VALVE AND ACTUATER TO THE LEFT OF THE PUMP. - Lakeview Pumping Station, Clarendon & Montrose Avenues, Chicago, Cook County, IL

  10. 40 CFR 52.1988 - Air contaminant discharge permits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Air contaminant discharge permits. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Oregon § 52.1988 Air contaminant... other provisions contained in Air Contaminant Discharge Permits issued by the State in accordance...

  11. ETR COMPRESSOR BUILDING, TRA643. CAMERA FACES NORTH. AIR HEATERS LINE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ETR COMPRESSOR BUILDING, TRA-643. CAMERA FACES NORTH. AIR HEATERS LINE UP AGAINST WALL, TO BE USED IN CONNECTION WITH ETR EXPERIMENTS. EACH HAD A HEAT OUTPUT OF 8 MILLION BTU PER HOUR, OPERATED AT 1260 DEGREES F. AND A PRESSURE OF 320 PSI. NOTE METAL WALLS AND ROOF. INL NEGATIVE NO. 56-3709. R.G. Larsen, Photographer, 11/13/1956 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  12. Operational test report for the 241-A-701 air compressor upgrade

    SciTech Connect

    Meeuwsen, W.E.

    1997-06-30

    A description and safety class designation of the accumulator and 701-A compressor system is contained in VTHC-SD-@-DA-137, Safety Classification (of the 241-A-70) Compressed Air System and shown on drawings H-2-62895, Sheet 2 and H-14-20308, Sheet 3. The design basis for the 241-A-702 Ventilation System Accumulator is contained in @-C-SD-@-DB-016, 241-A-702 Ventilation System Accumulator Design Basis.

  13. Comparison between the environmental damages of two axial air compressors manufactured by the firm Fini Compressori

    NASA Astrophysics Data System (ADS)

    Neri, Paolo; Bernardi, Giuseppe; Buttol, Patrizia; Naldi, Giovanni; Saric, Miroslav; Tani, Giovanni

    2001-02-01

    This study was performed jointly by ENEA (Italian National Agency for New Technologies, Energy and Environment), Bologna and Florence Universities and the firm FINI COMPRESSORI. A comparison is carried out between the environmental damages of two models (MK10 and MK94) of air axial compressors manufactured by FINI COMPRESSORI, with a volume of intaken air of 226 l/min, a power of 1.8 kW and a maximum pressure of 10 bar. The comparison is obtained by using LCA calculated by SimaPro 3.1 code and two methods: Eco-indicator 95 and a new method obtained by adding to the Eco-indicator 95 method other damage categories such as some raw material depletion, solid and energy. The system boundaries include raw material extraction and the end of life of the components and some special tools for manufacturing such as dies, moulds and shells. All metallic materials have the recycling as waste scenario. For LCA study we have considered the three components crankshaft, crankcase and valve plate for both the models, the air cooling conveyor for the MK94 and the surplus of consumed energy for the MK10. The conveyor decreases the temperature of air and therefore increases the compressor efficiency and reduces the electrical energy consumption during the use. From the LCA results, we can conclude that the introduction of the conveyor reduces the damage of MK10 model of 114.07 mPt and that the other modifications of the design increase the damage of MK10 model of 11 mPt. The damage of air compressor can be diminished by reusing crankshaft and crankcase. A design modification of the blades of the ventilator is proposed to avoid the conveyor.

  14. High ratio recirculating gas compressor

    DOEpatents

    Weinbrecht, John F.

    1989-01-01

    A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor.

  15. High ratio recirculating gas compressor

    DOEpatents

    Weinbrecht, J.F.

    1989-08-22

    A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor. 10 figs.

  16. Tesla coil discharges guided by femtosecond laser filaments in air

    NASA Astrophysics Data System (ADS)

    Brelet, Yohann; Houard, Aurélien; Arantchouk, Leonid; Forestier, Benjamin; Liu, Yi; Prade, Bernard; Carbonnel, Jérôme; André, Yves-Bernard; Mysyrowicz, André

    2012-04-01

    A Tesla coil generator was designed to produce high voltage pulses oscillating at 100 kHz synchronisable with a nanosecond temporal jitter. Using this compact high voltage generator, we demonstrate reproducible meter long discharges in air at a repetition rate of 1 Hz. Triggering and guiding of the discharges are performed in air by femtosecond laser filaments.

  17. Surface modification of compressor steels using thermally assisted ionic diffusion in the titanium plasma of a vacuum arc discharge

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.; Azarovskii, E. N.

    2015-11-01

    The thermally stimulated ionic diffusion (ionic modification) of titanium ions at the surfaces of EP866 and EI961 compressor steels is considered in the plasma of the high-current vacuum-arc discharge (VAD) in an ion-plasma MAP-3 plant. The dependences of the sample temperature in the sputtering chamber of the ion-plasma MAP-3 plant and the rate of specific change of the sample mass on the bias voltage at a VAD current of 300 A are obtained. The elemental composition of the surface layers of the samples subjected to ion treatment is studied. It is shown that, at a VAD current of 300 A and a bias voltage up to 400 V, the compressor steel sample temperature does not exceed 440°C and the inversion voltage, which determines the transition from coating condensation to ion etching of a substrate, is ~360 V for EP866 steel and ~390 V for EI961 steel. The corrosion resistance of the compressor steels modified at a VAD current of 300 A is investigated.

  18. Air compressor battery duration with mechanical ventilation in a field anesthesia machine.

    PubMed

    Szpisjak, Dale F; Giberman, Anthony A

    2015-05-01

    Compressed air to power field anesthesia machine ventilators may be supplied by air compressor with battery backup. This study determined the battery duration when the compPAC ventilator's air compressor was powered by NiCd battery to ventilate the Vent Aid Training Test Lung modeling high (HC = 0.100 L/cm H2O) and low (LC = 0.020 L/cm H2O) pulmonary compliance. Target tidal volumes (VT) were 500, 750, and 1,000 mL. Respiratory rate = 10 bpm, inspiratory-to-expiratory time ratio = 1:2, and fresh gas flow = 1 L/min air. N = 5 in each group. Control limits were determined from the first 150 minutes of battery power for each run and lower control limit = mean VT - 3SD. Battery depletion occurred when VT was below the lower control limit. Battery duration ranged from 185.8 (±3.2) minutes in the LC-1000 group to 233.3 (±3.6) minutes in the HC-750 group. Battery duration of the LC-1000 group was less than all others (p = 0.027). The differences among the non-LC-1000 groups were not clinically significant. PMID:25939102

  19. Application of Micro Discharge for Air Purification

    NASA Astrophysics Data System (ADS)

    Shimizu, Kazuo; Sugiyama, Takeki; L. S., Manisha Nishamani; Kanamori, Masaki

    Micro discharge is investigated which is occurred with a pair of electrodes covered with dielectric barrier. The discharge gap is set at an order of micro meters by changing a spacer from 0 to 100μm. Paschen's law states the minimum sparking voltage of various gases for respective discharge gaps in atmospheric pressure. In this paper, characteristics of micro discharges, such as discharge voltages, discharge currents, discharge power, which is obtained with the help of Lissajous figures, and the relationships between these characteristics are presented. Characteristics of ozone generation and treatment of high concentration NOx, which is contained in exhaust gas of automobiles, are investigated. Byproducts are confirmed by FT-IR and GC-MS.

  20. Benefits of compressor inlet air cooling for gas turbine cogeneration plants

    SciTech Connect

    De Lucia, M.; Lanfranchi, C.; Boggio, V.

    1996-07-01

    Compressor inlet air cooling is an effective method for enhancing the performance of gas turbine plants. This paper presents a comparative analysis of different solutions for cooling the compressor inlet air for the LM6000 gas turbine in a cogeneration plant operated in base load. Absorption and evaporative cooling systems are considered and their performance and economic benefits compared for the dry low-NO{sub x} LM6000 version. Reference is made to two sites in Northern and Southern Italy, whose climate data series for modeling the variations in ambient temperature during the single day were used to account for the effects of climate in the simulation. The results confirmed the advantages of inlet air cooling systems. In particular, evaporative cooling proved to be cost effective, though capable of supplying only moderate cooling, while absorption systems have a higher cost but are also more versatile and powerful in base-load operation. An integration of the two systems proved to be able to give both maximum performance enhancement and net economic benefit.

  1. Japanese and American competition in the development of scroll compressors and its impact on the American air conditioning industry

    SciTech Connect

    Ushimaru, Kenji )

    1990-02-01

    This report examines the technological development of scroll compressors and its impact on the air conditioning equipment industry. Scroll compressors, although considered to be the compressors of the future for energy-efficient residential heat pumps and possibly for many other applications, are difficult to manufacture on a volume-production base. The manufacturing process requires computer-aided, numerically controlled tools for high-precision fabrication of major parts. Japan implemented a global strategy for dominating the technological world market in the 1970s, and scroll compressor technology benefited from the advent of new-generation machine tools. As a result, if American manufacturers of scroll compressors purchase or are essentially forced to purchase numerically controlled tools from Japan in the future, they will then become dependent on their own competitors because the same Japanese conglomerates that make numerically controlled tools also make scroll compressors. This study illustrates the importance of the basic machine tool industry to the health of the US economy. Without a strong machine tool industry, it is difficult for American manufacturers to put innovations, whether patented or not, into production. As we experience transformation in the air conditioning and refrigeration market, it will be critical to establish a consistent national policy to provide healthy competition among producers, to promote innovation within the industry, to enhance assimilation of new technology, and to eliminate practices that are incompatible with these goals. 72 refs., 8 figs., 1 tab.

  2. The Mechanism of Stall Margin Improvement in a Centrifugal Compressor with the Air Bleeding Circumferential Grooves Casing Treatment

    NASA Astrophysics Data System (ADS)

    Gao, P.; Chu, W. L.; Wu, Y. H.

    The air bleeding circumferential grooves casing treatment has the potential to extent the operating range of centrifugal compressor with no loss in efficiency. A time accurate 3-dimentional numerical simulation was performed in a low speed centrifugal compressor with the air bleeding circumferential grooves casing treatment. The numerical results agreed well with experimental test data for the global performance. Detailed analyses of the flow visualization at the tip of blades have exposed the different tip flow topologies between the cases with casing treatment and with untreated smooth wall, and the reasons how the second flow vortex is retrained. The mechanism of stall margin improvement is gained finally.

  3. Centrifugal Compressor Surge Controlled

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.

    2003-01-01

    It shows the variation in compressor mass flow with time as the mass flow is throttled to drive the compressor into surge. Surge begins where wide variations in mass flow occur. Air injection is then turned on to bring about a recovery from the initial surge condition and stabilize the compressor. The throttle is closed further until surge is again initiated. Air injection is increased to again recover from the surge condition and stabilize the compressor.

  4. Modulated corona nanosecond discharge in air under ambient pressure

    NASA Astrophysics Data System (ADS)

    Lepekhin, N. M.; Priseko, Yu. S.; Filippov, V. G.; Bulatov, M. U.; Sukharevskii, D. I.; Syssoev, V. S.

    2015-04-01

    A unique type of corona discharge-modulated corona nanosecond discharge-has been obtained, the parameters of which have been determined in a geometric system of electrodes with a sharply heterogeneous electric field in air under ambient pressure and natural humidity.

  5. Pulsed positive streamer discharges in air at high temperatures

    NASA Astrophysics Data System (ADS)

    Ono, Ryo; Kamakura, Taku

    2016-08-01

    Atmospheric-pressure air pulsed positive streamer discharges are generated in a 13 mm point-plane gap in the temperature range of 293 K–1136 K, and the effect of temperature on the streamer discharges is studied. When the temperature is increased, the product of applied voltage and temperature VT proportional to the reduced electric field can be used as a primary parameter that determines some discharge parameters regardless of temperature. For a given VT, the transferred charge per pulse, streamer diameter, product of discharge energy and temperature, and length of secondary streamer are almost constant regardless of T, whereas the streamer velocity decreases with increasing T and the decay rate of the discharge current is proportional to 1/T. The N2(C) emission intensity is approximately determined by the discharge energy independent of T. These results are useful to predict the streamer discharge and its reactive species production when the ambient temperature is increased.

  6. Modification of various metals by volume discharge in air atmosphere

    NASA Astrophysics Data System (ADS)

    Shulepov, Mikhail A.; Erofeev, Mikhail V.; Oskomov, Konstantin V.; Tarasenko, Victor F.

    2015-12-01

    The results of the modification of stainless steel, niobium and titanium by volume discharge induced by a beam of runaway electrons in air under normal pressure are presented. Changes in the chemical composition of the surface layers of metal by the action of the discharge, structural changes and changes of hardness were studied. It has been found that the concentration of oxygen and carbon in the surface layers of the samples depend on the number of discharge pulses. The aim of this work is to find possible application of this type of discharge in science and industrial production.

  7. Performance of R-410A Alternative Refrigerants in a Reciprocating Compressor Designed for Air Conditioning Applications

    SciTech Connect

    Shrestha, Som S; Vineyard, Edward Allan; Mumpower, Kevin

    2016-01-01

    In response to environmental concerns raised by the use of refrigerants with high Global Warming Potential (GWP), the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) has launched an industry-wide cooperative research program, referred to as the Low-GWP Alternative Refrigerants Evaluation Program (AREP), to identify and evaluate promising alternative refrigerants for major product categories. After successfully completing the first phase of the program in December 2013, AHRI launched a second phase of the Low-GWP AREP in 2014 to continue research in areas that were not previously addressed, including refrigerants in high ambient conditions, refrigerants in applications not tested in the first phase, and new refrigerants identified since testing for the program began. Although the Ozone Depletion Potential of R-410A is zero, this refrigerant is under scrutiny due to its high GWP. Several candidate alternative refrigerants have already demonstrated low global warming potential. Performance of these low-GWP alternative refrigerants is being evaluated for Air conditioning and heat pump applications to ensure acceptable system capacity and efficiency. This paper reports the results of a series of compressor calorimeter tests conducted for the second phase of the AREP to evaluate the performance of R-410A alternative refrigerants in a reciprocating compressor designed for air conditioning systems. It compares performance of alternative refrigerants ARM-71A, L41-1, DR-5A, D2Y-60, and R-32 to that of R-410A over a wide range of operating conditions. The tests showed that, in general, cooling capacities were slightly lower (except for the R-32), but energy efficiency ratios (EER) of the alternative refrigerants were comparable to that of R-410A.

  8. Experimental investigation on materials and lubricants for sliding-vane air compressors

    NASA Astrophysics Data System (ADS)

    Murgia, Stefano; Valenti, Gianluca; Contaldi, Giulio; Valenti, Alessandro

    2015-08-01

    Positive-displacement compressors and, among them, sliding-vane rotary machines are widely used in the compressed air sector. As in many other industrial fields, the efficient utilization of energy has become a major goal also in this sector. The aim of the present activity is the experimental investigation on the influence of two vanes materials (cast iron and aluminium with anodized surface) and of four commercial lubricants (characterized by different formulations and additives concentrations) on the performance of a mid-capacity sliding-vane rotary compressor in a number of operating pressures. The performance is identified by both the volume flow rate and the absorbed mechanical power, evaluated according to the international standard ISO 5167 and ISO 1217. The campaign indicates that the considered lubricants do not affect appreciably the volumetric flow rate. On the other hand, the specific lubricants determine a variation of about 1% of the mechanical power for both materials, while the specific material a variation between 0.9% and 2.6%. The best performance is achieved by aluminium vanes and a synthetic poly-α-olefin lubricant.

  9. Rapid breakdown mechanisms of open air nanosecond dielectric barrier discharges.

    PubMed

    Ito, Tsuyohito; Kanazawa, Tatsuya; Hamaguchi, Satoshi

    2011-08-01

    The discharge initiation mechanism of nanosecond dielectric barrier discharges in open air has been clarified with time-dependent measurement of the discharge electric field by electric-field-induced coherent Raman scattering and optical emission. Our experimental observations have revealed that, in the prebreakdown phase of a nanosecond dielectric barrier discharge, the externally applied fast-rising electric field is strongly enhanced near the cathode due to large accumulation of space charge, which then strongly enhances ionization near the cathode. Once a sufficiently large number of ionizations take place, the location of peak ionization forms a front and propagates toward the cathode with strong optical emission, which establishes the discharge. This process is essentially different from the well-known Townsend mechanism for slower discharges. PMID:21902331

  10. Rapid Breakdown Mechanisms of Open Air Nanosecond Dielectric Barrier Discharges

    NASA Astrophysics Data System (ADS)

    Ito, Tsuyohito; Kanazawa, Tatsuya; Hamaguchi, Satoshi

    2011-08-01

    The discharge initiation mechanism of nanosecond dielectric barrier discharges in open air has been clarified with time-dependent measurement of the discharge electric field by electric-field-induced coherent Raman scattering and optical emission. Our experimental observations have revealed that, in the prebreakdown phase of a nanosecond dielectric barrier discharge, the externally applied fast-rising electric field is strongly enhanced near the cathode due to large accumulation of space charge, which then strongly enhances ionization near the cathode. Once a sufficiently large number of ionizations take place, the location of peak ionization forms a front and propagates toward the cathode with strong optical emission, which establishes the discharge. This process is essentially different from the well-known Townsend mechanism for slower discharges.

  11. Performance and economic enhancement of cogeneration gas turbines through compressor inlet air cooling

    NASA Astrophysics Data System (ADS)

    Delucia, M.; Bronconi, R.; Carnevale, E.

    1994-04-01

    Gas turbine air cooling systems serve to raise performance to peak power levels during the hot months when high atmospheric temperatures cause reductions in net power output. This work describes the technical and economic advantages of providing a compressor inlet air cooling system to increase the gas turbine's power rating and reduce its heat rate. The pros and cons of state-of-the-art cooling technologies, i.e., absorption and compression refrigeration, with and without thermal energy storage, were examined in order to select the most suitable cooling solution. Heavy-duty gas turbine cogeneration systems with and without absorption units were modeled, as well as various industrial sectors, i.e., paper and pulp, pharmaceuticals, food processing, textiles, tanning, and building materials. The ambient temperature variations were modeled so the effects of climate could be accounted for in the simulation. The results validated the advantages of gas turbine cogeneration with absorption air cooling as compared to other systems without air cooling.

  12. Measurement and prediction of heat transfer from compressor discs with a radial inflow of cooling air

    NASA Astrophysics Data System (ADS)

    Farthing, P. R.; Long, C. A.; Rogers, R. H.

    1991-06-01

    An internal theory is used to model the flow, and predict heat transfer rates, for corotating compressor disks with a superposed radial inflow of air. Measurements of heat transfer are also made, both in an experimental rig and in an engine. The flow structure comprises source and sink regions, Ekman-type layers and an inviscid central core. Entrainment occurs in the source region, the fluid being distributed into the two nonentraining Ekman-type layers. Fluid leaves the cavity via the sink region. The integral model is validated against the experimental data, although there are some uncertainties in modeling the exact thermal conditions of the experiment. The magnitude of the Nusselt numbers is affected by the rotational Reynolds number and dimensionless flowrate; the maximum value of Nu is found to occur near the edge of the source region. The heat transfer measurements using the engine data show acceptable agreement with theory and experiment.

  13. Effect of glow discharge air plasma on grain crops seed

    SciTech Connect

    Dubinov, A.E.; Lazarenko, E.M.; Selemir, V.D.

    2000-02-01

    Oat and barley seeds have been exposed to both continuous and pulsed glow discharge plasmas in air to investigate the effects on germination and sprout growth. Statistical analysis was used to evaluate the effect of plasma exposure on the percentage germination and length of sprout growth. A stimulating effect of plasma exposure was found together with a strong dependence on whether continuous or pulsed discharges were used.

  14. Electron concentration distribution in a glow discharge in air flow

    NASA Astrophysics Data System (ADS)

    Mukhamedzianov, R. B.; Gaisin, F. M.; Sabitov, R. A.

    1989-04-01

    Electron concentration distributions in a glow discharge in longitudinal and vortex air flows are determined from the attenuation of the electromagnetic wave passing through the plasma using microwave probes. An analysis of the distribution curves obtained indicates that electron concentration decreases in the direction of the anode. This can be explained by charge diffusion toward the chamber walls and electron recombination and sticking within the discharge.

  15. Glow Discharge Characteristics in Transverse Supersonic Air Flow

    NASA Astrophysics Data System (ADS)

    Timerkaev, B. A.; Zalyaliev, B. R.; Saifutdinov, A. I.

    2014-11-01

    A low pressure glow discharge in a transverse supersonic gas flow of air at pressures of the order 1 torr has been experimentally studied for the case where the flow only partially fills the inter electrode gap. It is shown that the space region with supersonic gas flow has a higher concentration of gas particles and, therefore, works as a charged particle generator. The near electrode regions of glow discharge are concentrated specifically in this region. This structure of glow discharge is promising for plasma deposition of coatings under ultralow pressures

  16. Characteristics of dielectric barrier discharge plasmas in atmospheric humid air

    NASA Astrophysics Data System (ADS)

    Fukuda, Y.; Fukui, K.; Iwami, R.; Matsuoka, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    Atmospheric pressure plasmas have a great advantage for industrial applications such as surface modifications, sterilization and film preparation. In particular, reactive plasmas including OH radicals can be generated in humid air. On the other hand, it is known that dielectric barrier discharge (DBD) plasmas in air are strongly affected by humidity. In this study, a twisted pair sample is used as a DBD electrode. The twisted pair consists of two enameled wires, and it is installed in a climate chamber to control ambient temperature and humidity. Repetitive impulse voltage pulses were applied to the twisted pair to produce DBD plasmas. Light emission, electromagnetic wave and current pulses were used to detect discharge activities. The discharge inception voltage (DIV) is basically determined by Paschen curve in air, however, the DIV was decreased by increasing the humidity. In addition, it was found that there were largely scattered data of DIV at the low humidity condition. After the pre-discharges, the DIV reached to the steady state value. On the other hand, there was no scattering of the observed DIV at the high humidity condition. Measurements of surface potential of the sample after the discharge show these behaviors could be explained by surface charge accumulation on the enameled wire. It is noted that there was no fluctuation in the DIV data in the case of unipolar voltage pulse.

  17. Development and Testing of a Temperature-swing Adsorption Compressor for Carbon Dioxide in Closed-loop Air Revitalization Systems

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.; Rosen, Micha; Affleck, David; LeVan, M. Douglas; Wang, Yuan

    2005-01-01

    The air revitalization system of the International Space Station (ISS) operates in an open loop mode and relies on the resupply of oxygen and other consumables from earth for the life support of astronauts. A compressor is required for delivering the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and thereby dosing the air-loop. We have developed a temperature-swing adsorption compressor (TSAC) that is energy efficient, quiet, and has no rapidly moving parts for performing these tasks. The TSAC is a solid-state compressor that has the capability to remove CO2 from a low- pressure source, and subsequently store, compress, and deliver at a higher pressure as required by a processor. The TSAC is an ideal interface device for CO2 removal and reduction units in the air revitalization loop of a spacecraft for oxygen recovery. This paper discusses the design and testing of a TSAC for carbon dioxide that has application in the ISS and future spacecraft for closing the air revitalization loop.

  18. Integrated Testing of a 4-Bed Molecular Sieve, Air-Cooled Temperature Swing Adsorption Compressor, and Sabatier Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Miller, Lee; Campbell, Melissa; Mulloth, Lila; Varghese, Mini

    2006-01-01

    Accumulation and subsequent compression of carbon dioxide that is removed from the space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The 4-Bed Molecular Sieve (4BMS) of ISS currently operates in an open loop mode without a compressor. The Sabatier Engineering Development Unit (EDU) processes waste CO2 to provide water to the crew. This paper reports the integrated 4BMS, air-cooled Temperature Swing Adsorption Compressor (TSAC), and Sabatier EDU testing. The TSAC prototype was developed at NASA Ames Research Center (ARC). The 4BMS was modified to a functionally flight-like condition at NASA Marshall Space Flight Center (MSFC). Testing was conducted at MSFC. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of the 4BMS and Sabatier.

  19. Nonlinear control of rotating stall and surge with axisymmetric bleed and air injection on axial flow compressors

    NASA Astrophysics Data System (ADS)

    Yeung, Chung-Hei (Simon)

    The study of compressor instabilities in gas turbine engines has received much attention in recent years. In particular, rotating stall and surge are major causes of problems ranging from component stress and lifespan reduction to engine explosion. In this thesis, modeling and control of rotating stall and surge using bleed valve and air injection is studied and validated on a low speed, single stage, axial compressor at Caltech. Bleed valve control of stall is achieved only when the compressor characteristic is actuated, due to the fast growth rate of the stall cell compared to the rate limit of the valve. Furthermore, experimental results show that the actuator rate requirement for stall control is reduced by a factor of fourteen via compressor characteristic actuation. Analytical expressions based on low order models (2--3 states) and a high fidelity simulation (37 states) tool are developed to estimate the minimum rate requirement of a bleed valve for control of stall. A comparison of the tools to experiments show a good qualitative agreement, with increasing quantitative accuracy as the complexity of the underlying model increases. Air injection control of stall and surge is also investigated. Simultaneous control of stall and surge is achieved using axisymmetric air injection. Three cases with different injector back pressure are studied. Surge control via binary air injection is achieved in all three cases. Simultaneous stall and surge control is achieved for two of the cases, but is not achieved for the lowest authority case. This is consistent with previous results for control of stall with axisymmetric air injection without a plenum attached. Non-axisymmetric air injection control of stall and surge is also studied. Three existing control algorithms found in literature are modeled and analyzed. A three-state model is obtained for each algorithm. For two cases, conditions for linear stability and bifurcation criticality on control of rotating stall are

  20. Synthesis of carbon nanotubes by arc discharge in open air.

    PubMed

    Paladugu, Mohan Chand; Maneesh, K; Nair, P Kesavan; Haridoss, Prathap

    2005-05-01

    In this work Carbon nanotubes have been synthesized by arc discharge in open air. A TIG welding ac/dc inverter was used as the power source for arc discharge. During each run of the arc discharge based synthesis, the anode was a low purity (approximately 85% C by weight) graphite rod. The effect of varying the atmosphere on the yield of soot of the carbon nanotube containing carbon soot has been studied. Various soots were produced, purified by oxidation and characterized to confirm formation of carbon nanotubes and their relative quality, using transmission electron microscopy, Raman spectroscopy, and XRD. It was found that the yield of soot formed on the cathode is higher when synthesis is carried out in open air than when carried out in a flowing argon atmosphere. When synthesized in open air, using a 7.2-mm-diameter graphite rod as anode, the yield of soot was around 50% by weight of the graphite consumed. Current and voltage for arcing were at identical starting values in all the experiments. This modified method does not require a controlled atmosphere as in the case of a conventional arc discharge method of synthesis and hence the cost of production may be reduced. PMID:16010933

  1. Acoustical analysis and modeling of reciprocating compressors, noise produced by gas pulsation, using four-pole method. I

    NASA Astrophysics Data System (ADS)

    Herfat, Ali T.; Seel, Robert V.

    2003-04-01

    Presented in Paper I are the fluid-structure interactions, structural dynamics, and thermodynamic analyses of reciprocating compressors (such as air conditioning and refrigeration reciprocating compressors). The compressor performance can be analyzed using the follows criteria: (1) thermodynamic model of the cylinder process, using the polytropic process model for thermodynamic model of cylinder; (2) suction and discharge valves dynamics analysis and modeling; (3) the valves modeling and the cylinder volume calculation; (4) Effective flow area and effective force area models.

  2. Experimental Investigation of Centrifugal Compressor Stabilization Techniques

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.

    2003-01-01

    Results from a series of experiments to investigate techniques for extending the stable flow range of a centrifugal compressor are reported. The research was conducted in a high-speed centrifugal compressor at the NASA Glenn Research Center. The stabilizing effect of steadily flowing air-streams injected into the vaneless region of a vane-island diffuser through the shroud surface is described. Parametric variations of injection angle, injection flow rate, number of injectors, injector spacing, and injection versus bleed were investigated for a range of impeller speeds and tip clearances. Both the compressor discharge and an external source were used for the injection air supply. The stabilizing effect of flow obstructions created by tubes that were inserted into the diffuser vaneless space through the shroud was also investigated. Tube immersion into the vaneless space was varied in the flow obstruction experiments. Results from testing done at impeller design speed and tip clearance are presented. Surge margin improved by 1.7 points using injection air that was supplied from within the compressor. Externally supplied injection air was used to return the compressor to stable operation after being throttled into surge. The tubes, which were capped to prevent mass flux, provided 9.3 points of additional surge margin over the baseline surge margin of 11.7 points.

  3. Selecting and sizing process compressors

    SciTech Connect

    Coker, A.K. )

    1994-07-01

    Proper compressor selection and sizing requires understanding the main types of compressors and their operation, using the right mathematical models for sizing both polytropic and adiabatic compressors, and providing for surge control and compressor discharge fluid treatment. There is no single type of compressor that can be adapted to a particular application. The operating conditions, space and weight restrictions must be reviewed before the appropriate compressor is selected. In addition, the type of driver must be selected since its operation and process conditions are interrelated. The different types of compressors can be classified into two basic types: reciprocating and centrifugal. Compressor performance often varies with changes in process conditions. Sometimes performance curves supplied by the manufacturer as discharge pressure and power requirement versus an inlet volumetric flow may not be valid for variations in process conditions. Lapina has provided a technique for obtaining a usable performance curve that is valid for the actual process conditions. The paper describes centrifugal and reciprocating compressors, compressor equations, the polytropic compressor, the adiabatic compressor, efficiency, mechanical losses, multicomponent gas streams, compressor surge control, and compressor fluids treatment.

  4. Energy balance in nanosecond pulse discharges in nitrogen and air

    NASA Astrophysics Data System (ADS)

    Shkurenkov, Ivan; Adamovich, Igor V.

    2016-02-01

    Kinetic modeling is used to analyze energy partition and energy transfer in nanosecond pulse discharges sustained between two spherical electrodes in nitrogen and air. The modeling predictions are compared with previous time-resolved temperature and {{\\text{N}}2}≤ft(X {}1Σ\\text{g}+,v=0-9\\right) vibrational population measurements by picosecond broadband coherent anti-Stokes Raman spectroscopy (CARS) and phase-locked Schlieren imaging. The model shows good agreement with experimental data, reproducing experimental discharge current pulse waveforms, as well as dominant processes of energy transfer in the discharge and the afterglow. Specifically, the results demonstrate that the temperature rise in the plasma occurs in two stages, (i) ‘rapid’ heating on sub-acoustic time scale, dominated by {{\\text{N}}2}≤ft(A {}3Σ\\text{u}+\\right) energy pooling processes, N2(B 3Πg) and N(2P,2D) quenching (in nitrogen), and by quenching of excited electronic states of N2 molecules by O2 (in air), and (ii) ‘slow’ heating due to N2 vibrational relaxation by O atoms (in air), nearly completely missing in nitrogen. Comparison of the model predictions with N2 vibrational level populations confirms that the N2 vibrational temperature rises after the discharge pulse is caused by the ‘downward’ vibrational-vibrational exchange depopulating higher vibrational levels and populating vibrational level v  =  1. The model reproduces temporal dynamics of vibrational level populations and temperature in the discharge and the afterglow, indicating that energy partition among different modes (vibrational, electronic, dissociation, and ionization) is predicted accurately. At the present conditions, energy fraction coupled to the positive column of the discharge filament in air is approximately 50%, with the rest coupled to the cathode layer. Nearly 10% of the total pulse energy is spent on O atom generation, and about 10% is thermalized on a sub-acoustic time scale

  5. Ozone generation using atmospheric pressure glow discharge in air

    NASA Astrophysics Data System (ADS)

    Buntat, Z.; Smith, I. R.; Razali, N. A. M.

    2009-12-01

    This paper presents results from a study into the generation of ozone by a stable atmospheric glow discharge, using dry air as the feeding gas for ozone generation. The power supply is 50 Hz ac, with the use of a perforated aluminium sheet for the electrodes and soda lime glass as a dielectric layer in a parallel-plate configuration, stabilizing the generation process and enabling ozone to be produced. The stable glow discharge spreads uniformly at a gas breakdown voltage below 4.8 kV and requires only 330 mW discharge power, with a limitation of 3 mm on the maximum gap spacing for the dry air. With the technique providing a high collision rate between the electrons and gas molecules during the discharge process, a high ozone yield is obtained. An analysis of the effect on the production rate of parameters such as the input voltage, gas flow rate and reaction chamber dimensions resulted in a highest efficiency of production of almost 350 g kWh-1 and confirms its potential as an important ozone generation technology.

  6. Recirculating rotary gas compressor

    DOEpatents

    Weinbrecht, J.F.

    1992-02-25

    A positive displacement, recirculating Roots-type rotary gas compressor is described which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits which return compressed discharge gas to the compressor housing, where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor. 12 figs.

  7. Recirculating rotary gas compressor

    DOEpatents

    Weinbrecht, John F.

    1992-01-01

    A positive displacement, recirculating Roots-type rotary gas compressor which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits (24 and 26) which return compressed discharge gas to the compressor housing (14), where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers (10 and 12) and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor.

  8. Frequency response of an axial-flow compressor exposed to inlet pressure perturbations

    NASA Technical Reports Server (NTRS)

    Milner, E. J.; Wenzel, L. M.; Paulovich, F. J.

    1974-01-01

    Experimental results of a series of engine tests designed to obtain the stage dynamics of an eight-stage axial-flow compressor over the frequency range of 0.5 to 200 hertz are presented. The total pressure at the compressor face was varied by means of a secondary air jet system installed in the engine inlet and positioned to oppose the primary airflow. Total-pressure probes located at each compressor stage were used to obtain the frequency response of each compressor-stage total pressure to the average compressor-inlet total pressure. The engine operating conditions were chosen to illustrate the effects of changing the rotor speed, changing the exhaust nozzle area, and isolating the compressor discharge pressure perturbations from the fuel control and hence, the fuel flow.

  9. Characteristics Of A Dielectric Barrier Discharge In Atmospheric Air

    NASA Astrophysics Data System (ADS)

    Lai, C. K.; Chin, O. H.; Thong, K. L.

    2009-07-01

    Parallel plate dielectric barrier discharges consisting of two electrodes with glass (ɛr = 7.5) and alumina (ɛr = 9.0) as the dielectric barrier were constructed. The system is powered by a variable 20 kV high voltage supply which is capable of delivering unipolar voltage pulses at frequency of 0.1-2.5 kHz and sinusoidal voltages at 6.5 kHz and above. At atmospheric pressure, the discharges exhibit either diffuse or filamentary appearance depending on parameters which include the series capacitance established by the electrodes with the dielectric barrier and varying air gap, dielectric material, and frequency of the supply voltages. This DBD system is built for the study of bacterial sterilization.

  10. A study on the oil flow characteristics in the inverter rotary compressor

    NASA Astrophysics Data System (ADS)

    Kim, H. J.; Kim, Y. J.

    2013-12-01

    In order to secure the reliability of the oil in the inverter rotary compressor used in the system multi-air conditioners in heating and cooling modes, it is necessary to study the oil flow characteristics which affect to the compressor efficiency. In this study, sight glasses were installed at the compressor and accumulator for oil flow measurements, and various experiments were performed to measure the amount of discharged oil for different refrigerant pipe lengths. On the basis of the experimental measurements, we compared the OCR (Oil Circulation Rate) results of the system multi-air conditioner for various operating conditions. The results are graphically depicted.

  11. Meeting 2006, outdoor noise directive (OND) noise levels for a diesel engine driven air compressor: A case study in noise reduction

    NASA Astrophysics Data System (ADS)

    Rowe, David F.

    2005-09-01

    In January 2006, the noise limits for many products in the European Union will drop by 2-3 dBA, as directed by 2000/14/EC ``Noise Emission in the Environment by Equipment Used Outdoors,'' commonly called the ``Outdoor Noise Directive,'' or ``OND.'' Air compressors are among the products addressed by this directive. At Ingersoll-Rand, significant effort has been directed at meeting the challenge of reducing noise on a variety of diesel engine driven air compressor platforms, ranging from 15 to 350 kW diesel engine power ratings. This paper presents a case study of the noise reduction on a 750 cfm (21 m3/min) air compressor operating at 300 psig (21 bar), to meet the 2006 OND noise limit of 100 LwA.

  12. The One Atmosphere Glow Discharge in Air: Phenomenology and Applications

    NASA Astrophysics Data System (ADS)

    Ben Gadri, Rami; Sherman, Daniel M.; Chen, Zhiyu; Karakaya, Fuat; Reece Roth, J.

    1999-10-01

    The existence of an atmospheric pressure RF glow plasma with the characteristics of a classical low pressure DC glow discharge has been experimentally and theoretically demonstrated [1, 2]. At the UTK Plasma Sciences Laboratory, the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) in air has been applied to a wide range of plasma processing applications. The technology is simple, technically attractive, and suitable for online treatment of webs and 3-dimensional workpieces. A parallel plate reactor and a Remote Exposure Reactor (RER) have been developed for direct plasma immersion and remote exposure, respectively. The RER is based on generating active species capable of sterilization and surface treatment in a uniform surface layer of the OAUGDP on planar panels [3], and convecting the active species to a remote chamber where the workpiece is located. A related surface plasma has been developed for indoor air filtration systems. In addition, the surface plasma on flat panels modified the boundary layer in wind tunnel tests to produce electrohydrodynamic (EHD) flow effects that can be used to increase or decrease aerodynamic drag [3]. [1] Massines et al., J. Appl. Phys., Vol. 83, N 6, pp 2950-2957, Mar. 1998. [2] J. R. Roth, "Industrial Plasma Engineering" Vol. I: Principles. Inst. Phys. Pub., Bristol and philadelphia, ISBN 0-7503-0318-2, 1995. [3] Roth et al., AIAA Paper 98-0328, 36th AIAA Meeting, Reno NV, 1998, Jan. 12-15.

  13. Nozzle for discharging ventilation air from a ventilation system

    SciTech Connect

    Elfverson, S.E.

    1986-09-30

    This patent describes a nozzle for discharging ventilation air from a ventilation system, preferably arranged in a vehicle, including at least one outlet housing with a through-flow duct for ventilation air, a fixed plate transverse to the flow duct and rigidly attached to the outlet housing, and a plurality of plates parallel to the fixed plate. These plates are mutually displaceable in a direction transverse to the flow duct under the action of a control lever passing through the plates, the plates being formed with perforation patterns, which in coaction form ventilation ducts through which the ventilation air can flow and in response to the setting of the control lever cause deviation of the flow direction of the ventilation air. Each displaceable plate is formed with a grid cross comprising at least two intersecting bars, of which one bar has a substantially circular cross section, while the other bar has a substantially elliptical cross section and wherein the control lever is adapted to grip round a grid cross, the control lever having two pairs of longitudinal slots. One pair of the slots is adapted to grip without play one of the intersecting bars in each respective grid cross. The other pair of slots comprises a first slot adapted to grip without play the other of the intersecting bars, and a second slot formed with a width disabling engagement with the other of the intersecting bars.

  14. Auto-ignition of lubricating oil working at high pressures in a compressor for an air conditioner.

    PubMed

    Kim, Chul Jin; Choi, Hyo Hyun; Sohn, Chae Hoon

    2011-01-15

    Auto-ignition of lubricating oil working in a compressor for an air conditioner is studied experimentally. The adopted lubricating oil is an unknown mixture with multi-components and known to have flash point temperature of 170 °C. First, its auto-ignition temperature is measured 365 °C at atmospheric pressure. The lubricating oil works under high-pressure condition up to 30 atm and it is heated and cooled down repeatedly. Accordingly, auto-ignition temperatures or flammable limits of lubricating oil are required at high pressures with respect to fire safety. Because there is not a standard test method for the purpose, a new ignition-test method is proposed in this study and thereby, auto-ignition temperatures are measured over the pressure range below 30 atm. The measured temperatures range from 215 °C to 255 °C and they strongly depend on pressure of gas mixture consisting of oil vapor, nitrogen, and oxygen. They are close to flash point temperature and the lubricating oil can be hazardous when it works for high-pressure operating condition and abundant air flows into a compressor. PMID:20934810

  15. Repetitively pulsed atmospheric pressure discharge treatment of rough polymer surfaces: I. Humid air discharges

    NASA Astrophysics Data System (ADS)

    Bhoj, Ananth N.; Kushner, Mark J.

    2008-08-01

    Plasmas generated at atmospheric pressure are used to functionalize the surfaces of polymers by creating new surface-resident chemical groups. The polymers used in textiles and biomedical applications often have non-planar surfaces whose functionalization requires penetration of plasma generated species into sometimes complex surface features. In this regard, the atmospheric pressure plasma treatment of a rough polypropylene surface was computationally investigated using a two-dimensional plasma hydrodynamics model integrated with a surface kinetics model. Repetitively pulsed discharges produced in a dielectric barrier-corona configuration in humid air were considered to affix O. Macroscopic non-uniformities in treatment result from the spatial variations in radical densities which depend on the polarity of the discharge. Microscopic non-uniformities arise due to the higher reactivity of plasma produced species, such as OH radicals, which are consumed before they can diffuse deeper into surface features. The consequences of applied voltage magnitude and polarity, and the relative humidity on discharge dynamics and radical generation leading to surface functionalization, are discussed.

  16. Limitation of discharge capacity and mechanisms of air-electrode deactivation in silicon-air batteries.

    PubMed

    Jakes, Peter; Cohn, Gil; Ein-Eli, Yair; Scheiba, Frieder; Ehrenberg, Helmut; Eichel, Rüdiger-A

    2012-11-01

    The electrocatalytical process at the air cathode in novel silicon-air batteries using the room-temperature ionic liquid hydrophilic 1-ethyl-3-methylimidazolium oligofluorohydrogenate [EMI⋅2.3 HF⋅F] as electrolyte and highly doped silicon wafers as anodes is investigated by electrochemical means, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. The results obtained by XPS and EPR provide a model to describe the limited discharge capacity by means of a mechanism of air-electrode deactivation. In that respect, upon discharge the silicon-air battery's cathode is not only blocked by silicon oxide reduction products, but also experiences a major modification in the MnO₂ catalyst nature. The proposed modification of the MnO₂ catalyst by means of a MnF₂ surface layer greatly impacts the Si-air performance and describes a mechanism relevant for other metal-air batteries, such as the lithium-air. Moreover, the ability for this deactivation layer to form is greatly impacted by water in the electrolyte. PMID:23033259

  17. [Air Dielectric Barrier Discharge Emission Spectrum Measurement and Particle Analysis of Discharge Process].

    PubMed

    Shen, Shuang-yan; Jin, Xing; Zhang, Peng

    2016-02-01

    The emission spectrum detection and diagnosis is one of the most common methods of application to the plasma. It provides wealth of information of the chemical and physical process of the plasma. The analysis of discharge plasma dynamic behavior plays an important role in the study of gas discharge mechanism and application. An air dielectric discharge spectrum measuring device was designed and the emission spectrum data was measured under the experimental condition. The plasma particles evolution was analyzed from the emission spectrum. The numerical calculation model was established and the density equation, energy transfer equation and the Boltzmann equation was coupled to analyze the change of the particle density to explain the emission spectrum characteristics. The results are that the particle density is growing with the increasing of reduced electric field. The particle density is one or two orders of magnitude difference for the same particle at the same moment for the reduced electric field of 40, 60 or 80 Td. A lot of N₂ (A³), N₂ (A³) and N₂ (C³) particles are generated by the electric field excitation. However, it transforms quickly due to the higher energy level. The transformation returns to the balance after the discharge of 10⁻⁶ s. The emission spectrometer measured in the experiments is mostly generated by the transition of excited nitrogen. The peak concentration of O₂ (A¹), O₂ (B¹) and O₂ (A³ ∑⁺u) is not low compared to the excited nitrogen molecules. These particles energy is relatively low and the transition spectral is longer. The spectrometer does not capture the oxygen emission spectrum. And the peak concentration of O particles is small, so the transition emission spectrum is weak. The calculation results of the stabled model can well explain the emission spectrum data. PMID:27209731

  18. [Temporal behavior of light emission of dielectric barrier discharges in air at atmospheric pressure].

    PubMed

    Yin, Zeng-qian; Dong, Li-fang; Han, Li; Li, Xue-chen; Chai, Zhi-fang

    2002-12-01

    The experimental setup of dielectric barrier discharge was designed which is propitious to optical measurement. Temporal behavior of light emission of dielectric barrier discharges (filamentary model) in air at atmospheric pressure was measured by using optical method. Temporal behavior of dielectric barrier discharges was obtained. The experimental results show that the discharge burst in each half cycle of applied voltage consists of a series of discharge pulses, the duration of each discharge pulse is about 30-50 ns, and the interval of the neighboring discharge pulses is about a few hundred ns. The result is of great importance to the application of dielectric barrier discharges. PMID:12914154

  19. Devices and methods of operation thereof for providing stable flow for centrifugal compressors

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J. (Inventor); Stevens, Mark A. (Inventor); Jett, Thomas A. (Inventor)

    2008-01-01

    Centrifugal compressor flow stabilizing devices and methods of operation thereof are disclosed that act upon the flow field discharging from the impeller of a centrifugal compressor and modify the flow field ahead of the diffuser vanes such that flow conditions contributing to rotating stall and surge are reduced or even eliminated. In some embodiments, shaped rods and methods of operation thereof are disclosed, whereas in other embodiments reverse-tangent air injection devices and methods are disclosed.

  20. Long-Duration Testing of a Temperature-Swing Adsorption Compressor for Carbon Dioxide for Closed-Loop Air Revitalization Systems

    NASA Technical Reports Server (NTRS)

    Rosen, Micha; Mulloth, Lila; Varghese, Mini

    2005-01-01

    This paper describes the results of long-duration testing of a temperature-swing adsorption compressor that has application in the International Space Station (ISS) and future spacecraft for closing the air revitalization loop. The air revitalization system of the ISS operates in an open loop mode and relies on the resupply of oxygen and other consumables from Earth for the life support of astronauts. A compressor is required for delivering the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and thereby closing the air-loop. The TSAC is a solid-state compressor that has the capability to remove CO2 from a low-pressure source, and subsequently store, compress, and deliver at a higher pressure as required by a processor. The TSAC is an ideal interface device for CO2 removal and reduction units in the air revitalization loop of a spacecraft for oxygen recovery. The TSAC was developed and its operation was successfully verified in integration tests with the flight-like Carbon Dioxide Removal Assembly (CDRA) at Marshall Space Flight Center prior to the long-duration tests. Long-duration tests reveal the impacts of repeated thermal cycling on the compressor components and the adsorbent material.

  1. Integrated Testing of a Carbon Dioxide Removal Assembly and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization

    NASA Technical Reports Server (NTRS)

    Knox, J. C.; Mulloth, Lila; Frederick, Kenneth; Affleck, Dave

    2003-01-01

    Accumulation and subsequent compression of carbon dioxide that is removed from space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The carbon dioxide removal assembly (CDRA) of ISS currently operates in an open loop mode without a compressor. This paper describes the integrated test results of a flight-like CDRA and a temperature-swing adsorption compressor (TSAC) for carbon dioxide removal and compression. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of CDRA.

  2. Air diverter for supercharger

    SciTech Connect

    Johnson, K.A.

    1986-10-28

    An engine supercharger is described which consists of a turbine housing, a main turbine wheel of the radial-inflow type located within the turbine housing, a compressor housing having an air entrance passageway, and a compressor wheel of the centrifugal type located within the compressor housing. It also includes a main shaft of annular construction interconnecting the turbine wheel and the compressor wheel whereby the two wheels rotate as a unit, an auxiliary turbine wheel of the axial flow type located downstream from the main turbine wheel, and a fan of the axial flow type located upstream from the compressor wheel. An auxiliary shaft extends within the main shaft between the auxiliary turbine and fan whereby the auxiliary turbine and fan rotate as a unit. An annular air collector chamber means is located immediately downstream from the fan in surrounding relation to the aforementioned entrance passageway for diverting some of the fan air from the compressor wheel. The fan comprises a hub and blades radiating outwardly therefrom. The air collector chamber is defined in part by an annular wall having a free edge located within the fan blade axial profile whereby the annular wall intercepts air discharged from outer tip areas of the fan blades to divert same away from the compressor wheel into the collector chamber.

  3. Very-High-Cycle-Fatigue of in-service air-engine blades, compressor and turbine

    NASA Astrophysics Data System (ADS)

    Shanyavskiy, A. A.

    2014-01-01

    In-service Very-High-Cycle-Fatigue (VHCF) regime of compressor vane and turbine rotor blades of the Al-based alloy VD-17 and superalloy GS6K, respectively, was considered. Surface crack origination occurred at the lifetime more than 1500 hours for vanes and after 550 hours for turbine blades. Performed fractographic investigations have shown that subsurface crack origination in vanes took place inspite of corrosion pittings on the blade surface. This material behavior reflected lifetime limit that was reached by the criterion VHCF. In superalloy GS6K subsurface fatigue cracking took place with the appearance of flat facet. This phenomenon was discussed and compared with specimens cracking of the same superalloy but prepared by the powder technology. In turbine blades VHCF regime appeared because of resonance of blades under the influenced gas stream. Both cases of compressor-vanes and turbine blades in-service cracking were discussed with crack growth period and stress equivalent estimations. Recommendations to continue aircrafts airworthiness were made for in-service blades.

  4. Benchmark performance analysis of an ECM-modulated air-to-air heat pump with a reciprocating compressor

    NASA Astrophysics Data System (ADS)

    Rice, C. K.

    1992-01-01

    A benchmark analysis was conducted to predict the maximum steady- state performance potential of a near-term modulating residential- size heat pump. Continuously variable-speed, permanent-magnet electronically commutated motors (ECMs) were assumed to modulate the compressor and the indoor and outdoor fans in conjunction with existing modulating reciprocating compressor technology. A modulating heat pump design tool was used to optimize this ECM benchmark heat pump, using speed ranges and total heat exchanger sizes per-unit-capacity equivalent to that used by the highest SEER-rated variable-speed unit presently on the market (SEER = 16.4). Parametric steady-state performance optimization was conducted at a nominal design cooling ambient of 95 F (35 C) and at three off-design ambients of 82 F (27.8 C) cooling and 47 F and 17 F (8.3 C and minus 8.3 C) heating. In comparison to the reference commercially available residential unit, the analysis for the ECM benchmark predicted steady-state heating COPs about 35 percent higher and a cooling EER almost 25 percent higher at the nominal design cooling condition. The cooling EER at 82 F (27.8 C) was 13 percent higher than that of the reference unit when a comparable sensible heat ratio of 0.71 was maintained, while an EER gain of 24 percent at the 82 F (27.8 C) rating point was predicted when the sensible heat ratio was relaxed to 0.83.

  5. Water injected fuel cell system compressor

    DOEpatents

    Siepierski, James S.; Moore, Barbara S.; Hoch, Martin Monroe

    2001-01-01

    A fuel cell system including a dry compressor for pressurizing air supplied to the cathode side of the fuel cell. An injector sprays a controlled amount of water on to the compressor's rotor(s) to improve the energy efficiency of the compressor. The amount of water sprayed out the rotor(s) is controlled relative to the mass flow rate of air inputted to the compressor.

  6. Charging of moving surfaces by corona discharges sustained in air

    NASA Astrophysics Data System (ADS)

    Wang, Jun-Chieh; Zhang, Daihua; Leoni, Napoleon; Birecki, Henryk; Gila, Omer; Kushner, Mark J.

    2014-07-01

    Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface is continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.

  7. Charging of moving surfaces by corona discharges sustained in air

    SciTech Connect

    Wang, Jun-Chieh Kushner, Mark J.; Zhang, Daihua; Leoni, Napoleon Birecki, Henryk Gila, Omer

    2014-07-28

    Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface is continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.

  8. 49 CFR 192.169 - Compressor stations: Pressure limiting devices.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Compressor stations: Pressure limiting devices... Pipeline Components § 192.169 Compressor stations: Pressure limiting devices. (a) Each compressor station... compressor station must extend to a location where the gas may be discharged without hazard....

  9. Influence of humidity on the characteristics of positive corona discharge in air

    NASA Astrophysics Data System (ADS)

    Xu, Pengfei; Zhang, Bo; Chen, Shuiming; He, Jinliang

    2016-06-01

    Detailed positive corona discharge characteristics, such as the corona onset voltage, pulse amplitude, repetition frequency, average corona current, rise time, and half-wave time, are systematically studied under different air humidity with a single artificial defect electrode. The experimental results indicate that the pulse amplitude decreases with the increase of air humidity; meanwhile, the repetition frequency increases as the air humidity increases. This phenomenon is different from that of negative corona discharge. Therefore, to have an insight into the mechanism of humidity influence on positive corona discharge, a positive corona discharge model based on the continuity equations is utilized. The simulations present a dynamic development of positive corona discharge and, meanwhile, reveal the humidity influence on positive corona discharge.

  10. Cold Climate Heat Pumps Using Tandem Compressors

    SciTech Connect

    Shen, Bo; Abdelaziz, Omar; Rice, C Keith; Baxter, Van D

    2016-01-01

    In cold climate zones, e.g. ASHRAE climate regions IV and V, conventional electric air-source heat pumps (ASHP) do not work well, due to high compressor discharge temperatures, large pressure ratios and inadequate heating capacities at low ambient temperatures. Consequently, significant use of auxiliary strip heating is required to meet the building heating load. We introduce innovative ASHP technologies as part of continuing efforts to eliminate auxiliary strip heat use and maximize heating COP with acceptable cost-effectiveness and reliability. These innovative ASHP were developed using tandem compressors, which are capable of augmenting heating capacity at low temperatures and maintain superior part-load operation efficiency at moderate temperatures. Two options of tandem compressors were studied; the first employs two identical, single-speed compressors, and the second employs two identical, vapor-injection compressors. The investigations were based on system modeling and laboratory evaluation. Both designs have successfully met the performance criteria. Laboratory evaluation showed that the tandem, single-speed compressor ASHP system is able to achieve heating COP = 4.2 at 47 F (8.3 C), COP = 2.9 at 17 F (-8.3 C), and 76% rated capacity and COP = 1.9 at -13 F (-25 C). This yields a HSPF = 11.0 (per AHRI 210/240). The tandem, vapor-injection ASHP is able to reach heating COP = 4.4 at 47 F, COP = 3.1 at 17 F, and 88% rated capacity and COP = 2.0 at -13 F. This yields a HSPF = 12.0. The system modeling and further laboratory evaluation are presented in the paper.

  11. Compressor performance

    SciTech Connect

    Gresh, M.T.

    1990-01-01

    This book provides information on the selection, operation, testing, and aerodynamic maintenance of axial and centrifugal compressors. Coverage includes design information, gas properties data, flow meter calculation, and troubleshooting guidelines. Design parameters are covered to provide the user with the basic how and why of compressor design. The many example problems along with reference data furnished will provide easy analysis of compressor performance.

  12. A study of the glow discharge characteristics of contact electrodes at atmospheric pressure in air

    SciTech Connect

    Liu, Wenzheng Sun, Guangliang Li, Chuanhui; Zhang, Rongrong

    2014-04-15

    Electric field distributions and discharge properties of rod-rod contact electrodes were studied under the condition of DBD for the steady generation of atmospheric pressure glow discharge plasma (APGD) in air. We found that under the effect of the initial electrons generated in a nanometer-scale gap, the rod-rod cross-contact electrodes yielded APGD plasma in air. Regarding the rod-rod cross-contact electrodes, increasing the working voltage expanded the strong electric field area of the gas gap so that both discharge area and discharge power increased, and the increase in the number of contact points kept the initial discharge voltage unchanged and caused an increase in the plasma discharge area and discharge power. A mesh-like structure of cross-contact electrodes was designed and used to generate more APGD plasma, suggesting high applicability.

  13. Flow Analysis around the Suction Valve and the Effect of the Flow on the Vibration-Reduction of the Valve in a Reciprocating Compressor for an Automotive Air-Conditioner

    NASA Astrophysics Data System (ADS)

    Sato, Taizo; Tsukiji, Tetsuhiro; Koyabu, Eitaro; Nakamura, Yusuke

    In the present study the simplified test model of the commercial reciprocating compressor for an automotive air-conditioner is designed to investigate the velocity distributions of the discharge flow from the suction valve using PIV (Particle Image Velocimetry) technique and to measure the displacement of the valve. The displacement of the conventional valve in the test model is observed using the high speed video camera and is also measured using a strain gauge. On the other hand the velocity distributions around the suction valve are measured using PIV and the relation between the velocity distributions and the movement of the valve is investigated. Furthermore the new valve with the shape improved from the conventional valve is designed and the results of the flow visualization and the measurement of the valve displacement for the new valve are compared with those of the conventional valve. We found that the vibration of the new valve can be suppressed compared with the conventional one from the experiment using both the present test model and the commercial reciprocating compressor. The reason of the vibration-reduction for the new valve is discussed from the results of the present flow analysis.

  14. 46 CFR 32.35-15 - Installation of air compressors on tank vessels contracted for on or after June 15, 1977-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... contracted for on or after June 15, 1977-TB/ALL. 32.35-15 Section 32.35-15 Shipping COAST GUARD, DEPARTMENT... June 15, 1977—TB/ALL. No tank vessel, except an oil pollution clean-up vessel, that carries petroleum products grades A thru D contracted for on or after June 15, 1977 may have an air compressor on an...

  15. 46 CFR 32.35-15 - Installation of air compressors on tank vessels contracted for on or after June 15, 1977-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... contracted for on or after June 15, 1977-TB/ALL. 32.35-15 Section 32.35-15 Shipping COAST GUARD, DEPARTMENT... June 15, 1977—TB/ALL. No tank vessel, except an oil pollution clean-up vessel, that carries petroleum products grades A thru D contracted for on or after June 15, 1977 may have an air compressor on an...

  16. On the dynamics of hot air plasmas related to lightning discharges: 2. Electrodynamics

    NASA Astrophysics Data System (ADS)

    Ripoll, Jean-François; Zinn, John; Colestock, Patrick L.; Jeffery, Christopher A.

    2014-08-01

    In this paper, we develop a model of electrical discharge in air for the simulation of some of the electrical processes involved in lightning discharges, as in lightning return strokes and dart leaders. The discharge is initiated by a vertical electrical field and modeled using a nonlinear R-L-C circuit model, with which we attempt to simulate initiation, growth, radial expansion, and decay of electrical discharges related to lightning. This gas dynamic type model includes also both detailed air chemistry and accurate air radiation transport, as described in the first part of this article. For certain parameter configurations, our first lightning-related discharge simulations compare well with lightning observations and actual knowledge in terms of chronology, charge and energy depleted, current created, electron concentration, temperature, pressure, and optical signature. We also discuss the difficulties to obtain fully consistent results due to the wide parameter variability, their uncertainty, and the complexity of the physics involved.

  17. One-dimensional Numerical Model of Transient Discharges in Air of a Spatial Plasma Ignition Device

    NASA Astrophysics Data System (ADS)

    Saceleanu, Florin N.

    This thesis examines the modes of discharge of a plasma ignition device. Oscilloscope data of the discharge voltage and current are analyzed for various pressures in air at ambient temperature. It is determined that the discharge operates in 2 modes: a glow discharge and a postulated streamer discharge. Subsequently, a 1-dimensional fluid simulation of plasma using the finite volume method (FVM) is developed to gain insight into the particle kinetics. Transient results of the simulation agree with theories of electric discharges; however, quasi-steady state results were not reached due to high diffusion time of ions in air. Next, an ordinary differential equation (ODE) is derived to understand the discharge transition. Simulated results were used to estimate the voltage waveform, which describes the ODE's forcing function; additional simulated results were used to estimate the discharge current and the ODE's non-linearity. It is found that the ODE's non-linearity increases exponentially for capacitive discharges. It is postulated that the non-linearity defines the mode transition observed experimentally. The research is motivated by Spatial Plasma Discharge Ignition (SPDI), an innovative ignition system postulated to increase combustion efficiency in automobile engines for up to 9%. The research thus far can only hypothesize SPDI's benefits on combustion, based on the literature review and the modes of discharge.

  18. Ultra-Efficient Engine Technology (UEET), Proof of Concept Compressor, Advanced Compressor Casing T

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Ultra-Efficient Engine Technology (UEET), Proof of Concept Compressor, Advanced Compressor Casing Treatment testing; close up - throttle valve -wide open; oil and air lines plus instrumentation between collector and gearbox.

  19. Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges

    NASA Astrophysics Data System (ADS)

    P. Sarrette, J.; Eichwald, O.; Marchal, F.; Ducasse, O.; Yousfi, M.

    2016-05-01

    The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air). The simulation involves the electro-dynamics, chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation. Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond. The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO. After 5 ms, the time corresponding to the occurrence of 50 successive discharge/post-discharge phases, a higher NO removal rate and a lower ozone production rate are found in humid air. This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.

  20. Voice-coil-actuated air valve for use in compressor forced-response testing

    NASA Astrophysics Data System (ADS)

    Mattern, Duane; Owen, A. Karl

    1995-05-01

    A 0-450 Hertz bandwidth, voice coil actuated, proportional sleeve valve is designed to modulate air mass flow by controlling the throat area of a choked flow. The valve was designed to deliver a mass flow of 0.072 kg/s with a maximum valve throat area of 41 mm2, a 689 kPA pressure difference across the valve, and 20 degree(s)C, air supply. The valve was developed with inexpensive, off-the-shelf components for use in ground-based forced response testing of compression systems. The design and operation of the valve are discussed and experimental test data of a prototype valve and air injector are compared to a mathematical model. Implementation of a set of eight of these valves in the compression system of a jet engine is discussed.

  1. Visualization of Rotor Tip Secondary Flows with Blade Tip Air Discharge and Suction in a Low-speed Turbine

    NASA Technical Reports Server (NTRS)

    Kofskey, Milton G; Allen, Hubert W

    1956-01-01

    Smoke was used to visualize outer-wall secondary flows in a low-speed turbine utilizing rotor tip air discharge and suction. Photographs as well as visual observations of the effect of tip air discharge and suction were made by independently varying the direction and quantity of the tip air discharge and suction, and varying tip clearance, and main-stream air speed. In addition, the cross-sectional area of the hollow blade discharge opening was varied for the case of tip air discharge.

  2. Effect of Inlet Air Distortion on the Steady-State and Surge Characteristics of an Axial-Flow Turbojet Compressor

    NASA Technical Reports Server (NTRS)

    Ciepluch, Carl C.

    1948-01-01

    An investigation was conducted in an altitude test chamber to determine the effects of inlet airflow distortion on the compressor steady-state and surge characteristics of a high-pressure ratio, axial-flow turbojet engine. Circumferential-type inlet flow distortions were investigated, which covered a range of distortion sector angles from 20 deg to 168 deg and distortion levels up to 22 percent. The presence of inlet airflow distortions at the compressor face resulted in a substantial increase in the local pressure ratio in the distorted region, primarily for the inlet stages. The local pressure ratio in the distorted region for the inlet stages increased as either the distortion sector angle decreased or the percent distortion increased. The average compressor-surge pressure ratio was much more sensitive to inlet airflow distortions at lower engine speeds than at engine speeds near rated. Hence, compressor-surge margin reduction due to inlet airflow distortion was quite severe at the lower engine speeds. Although the average compressor-surge pressure ratio was generally reduced with inlet flow distortion, local pressure ratios across the distorted sector of the compressor were obtained during surge and were significantly greater than the normal compressor-surge pressure ratio. This was a result of increased loading of the inlet stages in the distorted region.

  3. Multiple volume compressor for hot gas engine

    DOEpatents

    Stotts, Robert E.

    1986-01-01

    A multiple volume compressor for use in a hot gas (Stirling) engine having a plurality of different volume chambers arranged to pump down the engine when decreased power is called for and return the working gas to a storage tank or reservoir. A valve actuated bypass loop is placed over each chamber which can be opened to return gas discharged from the chamber back to the inlet thereto. By selectively actuating the bypass valves, a number of different compressor capacities can be attained without changing compressor speed whereby the capacity of the compressor can be matched to the power available from the engine which is used to drive the compressor.

  4. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    PubMed

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-01

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future. PMID:24975009

  5. Standing wave compressor

    DOEpatents

    Lucas, Timothy S.

    1991-01-01

    A compressor for compression-evaporation cooling systems, which requires no moving parts. A gaseous refrigerant inside a chamber is acoustically compressed and conveyed by means of a standing acoustic wave which is set up in the gaseous refrigerant. This standing acoustic wave can be driven either by a transducer, or by direct exposure of the gas to microwave and infrared sources, including solar energy. Input and output ports arranged along the chamber provide for the intake and discharge of the gaseous refrigerant. These ports can be provided with optional valve arrangements, so as to increase the compressor's pressure differential. The performance of the compressor in either of its transducer or electromagnetically driven configurations, can be optimized by a controlling circuit. This controlling circuit holds the wavelength of the standing acoustical wave constant, by changing the driving frequency in response to varying operating conditions.

  6. Large scale Tesla coil guided discharges initiated by femtosecond laser filamentation in air

    NASA Astrophysics Data System (ADS)

    Arantchouk, L.; Point, G.; Brelet, Y.; Prade, B.; Carbonnel, J.; André, Y.-B.; Mysyrowicz, A.; Houard, A.

    2014-07-01

    The guiding of meter scale electric discharges produced in air by a Tesla coil is realized in laboratory using a focused terawatt laser pulse undergoing filamentation. The influence of the focus position, the laser arrival time, or the gap length is studied to determine the best conditions for efficient laser guiding. Discharge parameters such as delay, jitter, and resistance are characterized. An increase of the discharge length by a factor 5 has been achieved with the laser filaments, corresponding to a mean breakdown field of 2 kV/cm for a 1.8 m gap length. Consecutive guided discharges at a repetition rate of 10 Hz are also reported.

  7. Modification of the surface layers of copper by a diffuse discharge in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Shulepov, Mikhail A.; Erofeev, Mikhail V.; Oskomov, Konstantin V.; Tarasenko, Victor F.

    2015-12-01

    The paper presents the results of examination of copper samples exposed to a diffuse discharge initiated by a runaway electron beam in air under normal pressure. The changes in the chemical composition of the surface layers of copper caused by the action of the discharge were investigated. It has been found that the oxygen and carbon concentrations in the surface layers depend on the number of discharge pulses. The study was aimed at finding possible ways of using this type of discharge in research and industry.

  8. Compressor ported shroud for foil bearing cooling

    DOEpatents

    Elpern, David G.; McCabe, Niall; Gee, Mark

    2011-08-02

    A compressor ported shroud takes compressed air from the shroud of the compressor before it is completely compressed and delivers it to foil bearings. The compressed air has a lower pressure and temperature than compressed outlet air. The lower temperature of the air means that less air needs to be bled off from the compressor to cool the foil bearings. This increases the overall system efficiency due to the reduced mass flow requirements of the lower temperature air. By taking the air at a lower pressure, less work is lost compressing the bearing cooling air.

  9. Experimental investigation on a turbine compressor for air supply system of a fuel cell

    SciTech Connect

    Matsuda, Masayasu; Tsuchiyama, Syozo

    1996-12-31

    This report covers part of a joint study on a PEFC propulsion system for surface ships, summarized in a presentation to this Seminar, entitled {open_quotes}Study on a Polymer Electrolyte Fuel Cell (PEFC) Propulsion System for Surface Ships{close_quotes}, and which envisages application to a 1,500 DWT cargo vessel. The aspect treated here concerns a study on the air supply system for the PEFC, with particular reference to system components.

  10. Cold-air performance of compressor-drive turbine of Department of Energy upgraded automobile gas turbine engine. 2: Stage performance

    NASA Technical Reports Server (NTRS)

    Roelke, R. J.; Haas, J. E.

    1982-01-01

    The aerodynamic performance of the compressor-drive turbine of the DOE upgraded gas turbine engine was determined in low temperature air. The as-received cast rotor blading had a significantly thicker profile than design and a fairly rough surface finish. Because of these blading imperfections a series of stage tests with modified rotors were made. These included the as-cast rotor, a reduced-roughness rotor, and a rotor with blades thinned to near design. Significant performance changes were measured. Tests were also made to determine the effect of Reynolds number on the turbine performance. Comparisons are made between this turbine and the compressor-drive turbine of the DOE baseline gas turbine engine.

  11. Flow Analysis around the Suction Valve and the Vibration Characteristics of the Valve in a Compressor for Automotive Air-Conditioner

    NASA Astrophysics Data System (ADS)

    Sato, Taizo; Tsukiji, Tetsuhiro

    The displacement of the suction valve in a compressor for automotive air-conditioning and the flow around the valve are investigated using a flow visualization technique. The visualization is conducted using the real compressor, which is improved to observe inside under the actual condition. Turbulent flow around the suction valve is solved using a computational fluid dynamics simulation. The flow is assumed to be an incompressible three-dimensional and viscous. The standard k-ε turbulent model is used Furthermore the pressure pulsations, the flow velocity and the displacements of the suction valves are analyzed numerically using the system simulation program we developed. The calculated results using a computational fluid dynamics are compared with the flow visualization results and the vibrations of the valve are discussed.

  12. 40 CFR 204.57-3 - Test compressor preparation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Test compressor preparation. 204.57-3... PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors § 204.57-3 Test compressor preparation. (a) Prior to the official test, the test compressor selected in accordance with §...

  13. 40 CFR 204.57-2 - Test compressor sample selection.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Test compressor sample selection. 204... ABATEMENT PROGRAMS NOISE EMISSION STANDARDS FOR CONSTRUCTION EQUIPMENT Portable Air Compressors § 204.57-2 Test compressor sample selection. (a) Compressors comprising the batch sample which are required to...

  14. Charge and discharge of polar cold air mass in northern hemispheric winter

    NASA Astrophysics Data System (ADS)

    Kanno, Yuki; Abdillah, Muhammad Rais; Iwasaki, Toshiki

    2015-09-01

    This study shows the variability of polar cold air mass amount below potential temperature of 280 K, and north of 45°N can be understood with a concept of charge and discharge, where anomalously large daily discharge indicates an intermittent occurrence of cold air outbreak. The polar cold air mass amount north of 45°N gradually charges up due to diabatic cooling but dramatically discharges due to cold air outbreak with a pulse width of about 5 days. Cold air outbreaks tend to bring colder winter in East Asia and the east coast of North America, while warmer winter prevails on the northern side of these regions. The cold air mass amount south of 45°N increases just after a cold air outbreak but returns to the normal level soon because of its life time of about 3 days. Therefore, monthly mean of total cold air mass amount in the Northern Hemisphere is negatively correlated with the monthly mean discharge.

  15. Atmospheric pressure discharge plasma decomposition for gaseous air contaminants -- Trichlorotrifluoroethane and trichloroethylene

    SciTech Connect

    Oda, Tetsuji; Yamashita, Ryuichi; Takahashi, Tadashi; Masuda, Senichi

    1996-03-01

    The decomposition performance of gaseous environmental destructive contaminants in air by using atmospheric pressure discharged plasma including the surface discharge induced plasma chemical processing (SPCP) was examined. The main contaminants tested were chlorofluorocarbon (CFC-113) and trichloroethylene, typically. The discharge exciting frequency range studied was wide--50 Hz to 50 kHz. Results showed the low frequency discharge requires high voltage to inject high electric power in the gas and to decompose the contaminants. A Gas Chromatograph Mass Spectrometer was used to analyze discharge products of dense CFC-113 or trichloroethylene. Among the detected products were HCl, CClFO, and CHCl{sub 3}. Two different electrode configurations; the silent discharge (coaxial) electrode and the coil-electrode were also tested and compared to each other as a gas reactor.

  16. The freely localized microwave discharge in air in the focused beam of the electromagnetic energy

    SciTech Connect

    Alexandrov, A.F.; Kuzovnikov, A.A.; Shibkov, V.M.

    1995-12-31

    The successfull use of the microwave discharge in many applications make it necessary to research the physics of a new kind of discharge - the electrodeless microwave discharge in the focused beam, in the free space and to search for ways to optimize this discharge parameters. The breakdown was performed in a discharge chamber at approximately free space conditions: R/{lambda}{much_gt}1, where R = 1 m is the discharge chamber`s dimension, {lambda} = 2 {divided_by} 10 cm is the wavelength of the microwave radiation. The focused electromagnetic beam was formed by a trumped-lens antenna. The electric field E{le}6 kV/cm, the density of energy flow S{le}10{sup 5} W/cm{sup 2}, the wave is linearity polarized. The microwave pulse duration could be changed from 1 {mu}s to 1 ms. The gas pressure (nitrogen, air) is varied from 1 to 760 torr.

  17. 40 CFR 52.1988 - Air contaminant discharge permits.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... other requirements of the SIP. Plant site emission limits and alternative emission limits (bubbles... Emission Limits for Sources of Hazardous Air Pollutants” and 060(8) “Alternative Emission Controls...

  18. 40 CFR 52.1988 - Air contaminant discharge permits.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... other requirements of the SIP. Plant site emission limits and alternative emission limits (bubbles... Emission Limits for Sources of Hazardous Air Pollutants” and 060(8) “Alternative Emission Controls...

  19. 40 CFR 52.1988 - Air contaminant discharge permits.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... other requirements of the SIP. Plant site emission limits and alternative emission limits (bubbles... Emission Limits for Sources of Hazardous Air Pollutants” and 060(8) “Alternative Emission Controls...

  20. 40 CFR 52.1988 - Air contaminant discharge permits.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... other requirements of the SIP. Plant site emission limits and alternative emission limits (bubbles... Emission Limits for Sources of Hazardous Air Pollutants” and 060(8) “Alternative Emission Controls...

  1. Semi-active compressor valve

    DOEpatents

    Brun, Klaus; Gernentz, Ryan S.

    2010-07-27

    A method and system for fine-tuning the motion of suction or discharge valves associated with cylinders of a reciprocating gas compressor, such as the large compressors used for natural gas transmission. The valve's primary driving force is conventional, but the valve also uses an electromagnetic coil to sense position of the plate (or other plugging element) and to provide an opposing force prior to impact.

  2. Ozone production by a dc corona discharge in air contaminated by n-heptane

    NASA Astrophysics Data System (ADS)

    Pekárek, S.

    2008-01-01

    Beneficial purposes of ozone such as elimination of odours, harmful bacteria and mildew can be used for transportation of food, fruits and vegetables with the aim to extend their storage life. To date the main technique used for this purpose in the transportation of these commodities, e.g. by trucks, was cooling. Here a combination of cooling together with the supply of ozone into containers with these commodities is considered. For these purposes we studied the effect of air contamination by n-heptane (part of automotive fuels) and humidity on ozone production by a dc hollow needle to mesh corona discharge. We found that, for both polarities of the needle electrode, addition of n-heptane to air (a) decreases ozone production; (b) causes discharge poisoning to occur at lower current than for air; (c) does not substantially influence the current for which the ozone production reaches the maximum. Finally the maximum ozone production for the discharge in air occurs for the same current as the maximum ozone production for the discharge contaminated by n-heptane. We also found that humidity decreases ozone production from air contaminated by n-heptane irrespective of the polarity of the coronating needle electrode. This dependence is stronger for the discharge with the needle biased positively.

  3. Impacts of air pressure on the evolution of nanosecond pulse discharge products

    NASA Astrophysics Data System (ADS)

    Yu, Jin-Lu; He, Li-Ming; Ding, Wei; Wang, Yu-Qian; Du, Chun

    2013-05-01

    Based on the nonequilibrium plasma dynamics of air discharge, a dynamic model of zero-dimensional plasma is established by combining the component density equation, the Boltzmann equation, and the energy transfer equation. The evolution properties of nanosecond pulse discharge (NPD) plasma under different air pressures are calculated. The results show that the air pressure has significant impacts on the NPD products and the peak values of particle number density for particles such as O atoms, O3 molecules, N2(A3) molecules in excited states, and NO molecules. It increases at first and then decreases with the increase of air pressure. On the other hand, the peak values of particle number density for N2(B3) and N2(C3) molecules in excited states are only slightly affected by the air pressure.

  4. Compressor Calorimeter Test of R-410A Alternative: R-32/134a Mixture Using a Scroll Compressor

    SciTech Connect

    Shrestha, Som S; Sharma, Vishaldeep; Abdelaziz, Omar

    2014-02-01

    As a contribution to the AHRI Low-GWP Alternative Refrigerants Evaluation Program (AREP), this study compares the performance of lower-GWP alternative refrigerant R-32 + R-134a mixture, to that of refrigerant R-410A (baseline) in a scroll compressor designed for air-conditioning and heat pump applications. These comparisons were carried out via compressor calorimeter tests performed on a compressor designed for refrigerant R-410A and having a nominal rated capacity of 21,300 Btu/hr. Tests were conducted over a suction dew point temperature range of 10 F to 55 F in 5 F increments and a discharge dew point temperature range of 70 F to 140 F in 10 F increments. All the tests were performed with 20 F superheat, 40 F superheat, and 65 F suction temperature. A liquid subcooling level of 15 F was maintained for all the test conditions. The tests showed that the discharge temperature of the alternative refrigerant was higher than that of R-410A at all test conditions. Also, the energy efficiency ratio (EER) and cooling capacity of compressor using the alternative refrigerant were slightly lower in comparison to that of R-410A.

  5. Dielectric barrier discharge in air with a controllable spatial distribution—a tomographic investigation

    NASA Astrophysics Data System (ADS)

    van der Schans, M.; Sobota, A.; Kroesen, G. M. W.

    2016-05-01

    A novel dielectric barrier discharge source with a controllable discharge distribution has been designed for operation in atmospheric air. A predictable distribution has been achieved through the design of the powered electrode and the dielectric barrier. Optical emission tomography is used to study the discharge distribution. The method and its applicability in studies of non-symmetric plasmas are discussed in the paper. The results show that a desired discharge distribution may be achieved through the manipulation of the electric field amplification by the powered electrode and it is found that the discharge shape resembles the field imposed at the powered electrode only. Together with the flexibility of the plasma source design, this can prove highly advantageous for the treatment of irregularly shaped surfaces in plasma medicine and plasma surface processing at atmospheric pressure.

  6. Piezoelectric transformers for low-voltage generation of gas discharges and ionic winds in atmospheric air

    SciTech Connect

    Johnson, Michael J.; Go, David B.

    2015-12-28

    To generate a gas discharge (plasma) in atmospheric air requires an electric field that exceeds the breakdown threshold of ∼30 kV/cm. Because of safety, size, or cost constraints, the large applied voltages required to generate such fields are often prohibitive for portable applications. In this work, piezoelectric transformers are used to amplify a low input applied voltage (<30 V) to generate breakdown in air without the need for conventional high-voltage electrical equipment. Piezoelectric transformers (PTs) use their inherent electromechanical resonance to produce a voltage amplification, such that the surface of the piezoelectric exhibits a large surface voltage that can generate corona-like discharges on its corners or on adjacent electrodes. In the proper configuration, these discharges can be used to generate a bulk air flow called an ionic wind. In this work, PT-driven discharges are characterized by measuring the discharge current and the velocity of the induced ionic wind with ionic winds generated using input voltages as low as 7 V. The characteristics of the discharge change as the input voltage increases; this modifies the resonance of the system and subsequent required operating parameters.

  7. Piezoelectric transformers for low-voltage generation of gas discharges and ionic winds in atmospheric air

    NASA Astrophysics Data System (ADS)

    Johnson, Michael J.; Go, David B.

    2015-12-01

    To generate a gas discharge (plasma) in atmospheric air requires an electric field that exceeds the breakdown threshold of ˜30 kV/cm. Because of safety, size, or cost constraints, the large applied voltages required to generate such fields are often prohibitive for portable applications. In this work, piezoelectric transformers are used to amplify a low input applied voltage (<30 V) to generate breakdown in air without the need for conventional high-voltage electrical equipment. Piezoelectric transformers (PTs) use their inherent electromechanical resonance to produce a voltage amplification, such that the surface of the piezoelectric exhibits a large surface voltage that can generate corona-like discharges on its corners or on adjacent electrodes. In the proper configuration, these discharges can be used to generate a bulk air flow called an ionic wind. In this work, PT-driven discharges are characterized by measuring the discharge current and the velocity of the induced ionic wind with ionic winds generated using input voltages as low as 7 V. The characteristics of the discharge change as the input voltage increases; this modifies the resonance of the system and subsequent required operating parameters.

  8. Role of water and discharge mode on modulating properties in an atmospheric air MHCD jet

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Wang, Chenying; Lei, Juzhang; Hu, Huimin; Zheng, Peichao; He, Wei

    2016-04-01

    A portable micro hollow cathode discharge (MHCD) device was designed in this paper to generate water-air plasma jet. The results showed that MHCD jet pattern was changed from self-pulsing discharge mode to DC mode with the increasing of voltage, and the critical voltage value of discharge mode increased with the rise of gas flow. In order to study the influences of discharge mode and water content on MHCD jet, the electrical characteristics and radicals were all measured in different conditions. We found that the length of jet decreased and temperature increased with raising water-air ratio, and during self-pulsing discharge mode, •OH content was extremely low because of the low energy of electron, but level of NO was raised with gradually increasing applied voltage. In DC mode, the results showed there was least NO content, on the other hand •OH content increased with rise of voltage and water-air ratio. O existed in both discharge modes and the effect of water content on the O production was complex. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.

  9. Cold-air performance of compressor-drive turbine of Department of Energy upgraded automobile gas turbine engine. 1: Volute-manifold and stator performance

    NASA Technical Reports Server (NTRS)

    Roelke, R. J.; Haas, J. E.

    1981-01-01

    The aerodynamic performance of the inlet manifold and stator assembly of the compressor drive turbine was experimentally determined with cold air as the working fluid. The investigation included measurements of mass flow and stator-exit fluid torque as well as radial surveys of total pressure and flow angle at the stator inlet and annulus surveys of total pressure and flow angle at the stator exit. The stator-exit aftermixed flow conditions and overall stator efficiency were obtained and compared with their design values and the experimental results from three other stators. In addition, an analysis was made to determine the constituent aerodynamic losses that made up the stator kinetic energy loss.

  10. Indoor air cleaning using a pulsed discharge plasma

    SciTech Connect

    Mizuno, Akira; Kisanuki, Yoshiyuki; Noguchi, Masanobu; Katsura, Shinji; Lee, S.H.; Hong, Y.K.; Shin, S.Y.; Kang, J.H.

    1999-12-01

    The purpose of this paper is to develop a high-efficiency air-cleaning system for air pollutants such as tobacco smoke found in indoor environments. The authors investigated the basic characteristics of treating particulate matter and acetaldehyde (CH{sub 3}CHO) in a one-pass test using a pulse generator and a plasma-driven catalyst reactor, both of which are attachable to an air conditioner. Using a circulation test, the decrease in acetaldehyde concentration was measured in a closed vessel where the reactor had been placed. The removal efficiencies of particulate matter and acetaldehyde in the one-pass test (residence time of 10 ms) were 70% and 27%, respectively. In the circulation test, 98% of the suspended particles were collected after 2 min of operation and the acetaldehyde concentration decreased by 70% after 50 mins. It is believed that the TiO{sub 2} catalyst is excited by plasma-induced high-energy particles (electrons, photons, and metastable molecules), resulting in an enhanced pollutant removal. These test results indicate that the combination of plasma with TiO{sub 2} is a potential alternative in treating the pollutants in environmental tobacco smoke.

  11. Refrigeration system having standing wave compressor

    DOEpatents

    Lucas, Timothy S.

    1992-01-01

    A compression-evaporation refrigeration system, wherein gaseous compression of the refrigerant is provided by a standing wave compressor. The standing wave compressor is modified so as to provide a separate subcooling system for the refrigerant, so that efficiency losses due to flashing are reduced. Subcooling occurs when heat exchange is provided between the refrigerant and a heat pumping surface, which is exposed to the standing acoustic wave within the standing wave compressor. A variable capacity and variable discharge pressure for the standing wave compressor is provided. A control circuit simultaneously varies the capacity and discharge pressure in response to changing operating conditions, thereby maintaining the minimum discharge pressure needed for condensation to occur at any time. Thus, the power consumption of the standing wave compressor is reduced and system efficiency is improved.

  12. Influence of the voltage polarity on the properties of a nanosecond surface barrier discharge in atmospheric-pressure air

    SciTech Connect

    Nudnova, M. M.; Aleksandrov, N. L.; Starikovskii, A. Yu.

    2010-01-15

    The properties of a surface barrier discharge in atmospheric-pressure air at different polarities of applied voltage were studied experimentally. The influence of the voltage polarity on the spatial structure of the discharge and the electric field in the discharge plasma was determined by means of spectroscopic measurements. It is found that the energy deposited in the discharge does not depend on the voltage polarity and that discharges of positive polarity are more homogenous and the electric fields in them are higher.

  13. Anomalous Discharge Product Distribution in Lithium-Air Cathodes: A Three Dimensional View

    SciTech Connect

    Nanda, Jagjit; Allu, Srikanth; Bilheux, Hassina Z; Dudney, Nancy J; Pannala, Sreekanth; Veith, Gabriel M; Voisin, Sophie; Walker, Lakeisha MH; Archibald, Richard K

    2012-01-01

    Using neutron tomographic imaging we report for the first time three dimensional spatial distribution of lithium product distribution in electrochemically discharged Lithium-Air cathodes. Neutron imaging finds a non-uniform lithium product distribution across the electrode thickness; the lithium species concentration being higher near the edges of the Li-air electrode and relatively uniform in the center of the electrode. The experimental neutron images were analyzed in context of results obtained from 3D modeling of the spatial lithium product distribution using a kinetically coupled diffusion based transport model that accounts for the dynamical reaction rate dependence on the discharge product formation, porosity changes and mass transfer.

  14. Flow Range of Centrifugal Compressor Being Extended

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.

    2001-01-01

    General Aviation will benefit from turbine engines that are both fuel-efficient and reliable. Current engines fall short of their potential to achieve these attributes. The reason is compressor surge, which is a flow stability problem that develops when the compressor is subjected to conditions that are outside of its operating range. Compressor surge can occur when fuel flow to the engine is increased, temporarily back pressuring the compressor and pushing it past its stability limit, or when the compressor is subjected to inlet flow-field distortions that may occur during takeoff and landing. Compressor surge can result in the loss of an aircraft. As a result, engine designers include a margin of safety between the operating line of the engine and the stability limit line of the compressor. Unfortunately, the most efficient operating line for the compressor is usually closer to its stability limit line than it is to the line that provides an adequate margin of safety. A wider stable flow range will permit operation along the most efficient operating line of the compressor, improving the specific fuel consumption of the engine and reducing emissions. The NASA Glenn Research Center is working to extend the stable flow range of the compressor. Significant extension has been achieved in axial compressors by injecting air upstream of the compressor blade rows. Recently, the technique was successfully applied to a 4:1 pressure ratio centrifugal compressor by injecting streams of air into the diffuser. Both steady and controlled unsteady injection were used to inject air through the diffuser shroud surface and extend the range. Future work will evaluate the effect of air injection through the diffuser hub surface and diffuser vanes with the goal of maximizing the range extension while minimizing the amount of injected air that is required.

  15. Semi-analytical modelling of positive corona discharge in air

    NASA Astrophysics Data System (ADS)

    Pontiga, Francisco; Yanallah, Khelifa; Chen, Junhong

    2013-09-01

    Semianalytical approximate solutions of the spatial distribution of electric field and electron and ion densities have been obtained by solving Poisson's equations and the continuity equations for the charged species along the Laplacian field lines. The need to iterate for the correct value of space charge on the corona electrode has been eliminated by using the corona current distribution over the grounded plane derived by Deutsch, which predicts a cos m θ law similar to Warburg's law. Based on the results of the approximated model, a parametric study of the influence of gas pressure, the corona wire radius, and the inter-electrode wire-plate separation has been carried out. Also, the approximate solutions of the electron number density has been combined with a simplified plasma chemistry model in order to compute the ozone density generated by the corona discharge in the presence of a gas flow. This work was supported by the Consejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) and by the Ministerio de Ciencia e Innovacion, Spain, within the European Regional Development Fund contracts FQM-4983 and FIS2011-25161.

  16. Influence of humidity on the characteristics of negative corona discharge in air

    NASA Astrophysics Data System (ADS)

    Xu, Pengfei; Zhang, Bo; He, Jinliang; Chen, Shuiming

    2015-09-01

    Detailed negative corona discharge characteristics, such as the pulse amplitude, repetition frequency, average corona current, rise time, and half-wave time, are systematically studied under various air humidities with a single artificial defect electrode. The experimental result reveals that the pulse amplitude increases with the increase of air humidity; meanwhile, the repetition frequency deceases as the air humidity increases. Empirical formulae are first established for the pulse amplitude and repetition frequency with the humidity factor taken into consideration. The effective ionization integral is calculated and a positive correlation is found between the integral and the pulse amplitude. Furthermore, a simplified negative-ion cloud model is built up to investigate the mechanism of the humidity's influence on negative corona discharge. Based on the theoretical analyses, the correlation between pulse amplitude, repetition frequency, and air humidity is well explained.

  17. Influence of humidity on the characteristics of negative corona discharge in air

    SciTech Connect

    Xu, Pengfei Zhang, Bo He, Jinliang Chen, Shuiming

    2015-09-15

    Detailed negative corona discharge characteristics, such as the pulse amplitude, repetition frequency, average corona current, rise time, and half-wave time, are systematically studied under various air humidities with a single artificial defect electrode. The experimental result reveals that the pulse amplitude increases with the increase of air humidity; meanwhile, the repetition frequency deceases as the air humidity increases. Empirical formulae are first established for the pulse amplitude and repetition frequency with the humidity factor taken into consideration. The effective ionization integral is calculated and a positive correlation is found between the integral and the pulse amplitude. Furthermore, a simplified negative-ion cloud model is built up to investigate the mechanism of the humidity's influence on negative corona discharge. Based on the theoretical analyses, the correlation between pulse amplitude, repetition frequency, and air humidity is well explained.

  18. Space Charge Transient Kinetic Characteristics in DC Air Corona Discharge at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Liu, Xinghua; Xian, Richang; Sun, Xuefeng; Wang, Tao; Lv, Xuebin; Chen, Suhong; Yang, Fan

    2014-08-01

    Investigating the corona mechanism plays a key role in enhancing the performance of electrical insulation systems. Numerical simulation offers a better understanding of the physical characteristics of air corona discharges. Using a two-dimensional axisymmetrical kinetics model, into which the photoionization effect is incorporated, the DC air corona discharge at atmosphere pressure is studied. The plasma model is based on a self-consistent, multi-component, and continuum description of the air discharge, which is comprised of 12 species and 22 reactions. The discharge voltage-current characteristic predicted by the model is found to be in quite good agreement with experimental measurements. The behavior of the electronic avalanche progress is also described. O2+ and N2+ are the dominant positive ions, and the values of O- and O2- densities are much smaller than that of the electron. The electron and positive ion have a low-density thin layer near the anode, which is a result of the surface reaction and absorption effect of the electrode. As time progresses, the electric field increases and extends along the cathode surface, whereas the cathode fall shrinks after the corona discharge hits the cathode; thus, in the cathode sheath, the electron temperature increases and the position of its peak approaches to the cathode. The present computational model contributes to the understanding of this physical mechanism, and suggests ways to improve the electrical insulation system.

  19. Discharge product morphology versus operating temperature in non-aqueous lithium-air batteries

    NASA Astrophysics Data System (ADS)

    Tan, P.; Shyy, W.; Zhao, T. S.; Wei, Z. H.; An, L.

    2015-03-01

    During the discharge process of non-aqueous lithium-air batteries, a solid product, Li2O2, forms in the pores of the porous cathode, and eventually causes the discharge process to cease. During the charge process, solid Li2O2 needs to be electrochemically oxidized. The morphology of the discharge product is, therefore, critically related to the capacity and reversibility of the battery. In this work, we experimentally show that for a given design of the cathode, the shape of the discharge product Li2O2 at a given discharge current density remains almost unchanged with a change in the operating temperature, but the size decreases with an increase in the temperature. We also demonstrate that the product shape varies with the discharge current density at a given temperature. The practical implication of these findings is that the capacity, charge voltage, and cyclability of a given non-aqueous lithium-air battery are affected by the operating temperature.

  20. Two-stage energy thermalization mechanism in nanosecond pulse discharges in air and hydrogen-air mixtures

    NASA Astrophysics Data System (ADS)

    Lanier, Suzanne; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.

    2015-04-01

    Time-resolved and spatially resolved temperature measurements, by pure rotational picosecond broadband coherent anti-Stokes Raman spectroscopy (CARS), and kinetic modeling calculations are used to study kinetics of energy thermalization in nanosecond pulse discharges in air and hydrogen-air mixtures. The diffuse filament, nanosecond pulse discharge (pulse duration ˜100 ns) is sustained between two spherical electrodes and is operated at a low pulse repetition rate to enable temperature measurements over a wide range of time scales after the discharge pulse. The experimental results demonstrate high accuracy of pure rotational ps CARS for thermometry measurements in highly transient non-equilibrium plasmas. Rotational-translational temperatures are measured for time delays after the pulse ranging from tens of ns to tens of ms, spanning several orders of magnitude of time scales for energy thermalization in non-equilibrium plasmas. In addition, radial temperature distributions across the plasma filament are measured for several time delays after the discharge pulse. Kinetic modeling calculations using a state-specific master equation kinetic model of reacting hydrogen-air plasmas show good agreement with experimental data. The results demonstrate that energy thermalization and temperature rise in these plasmas occur in two clearly defined stages, (i) ‘rapid’ heating, caused by collisional quenching of excited electronic states of N2 molecules by O2, and (ii) ‘slow’ heating, caused primarily by N2 vibrational relaxation by O atoms (in air) and by chemical energy release during partial oxidation of hydrogen (in H2-air). The results have major implications for plasma assisted combustion and plasma flow control.

  1. 49 CFR 230.71 - Orifice testing of compressors.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Compressor size Single strokes per minute Diameter of orifice(in inches) Air pressure maintained(in pounds... feet the speed of compressor may be increased 5 single strokes per minute for each 1,000 feet...

  2. 49 CFR 230.71 - Orifice testing of compressors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Compressor size Single strokes per minute Diameter of orifice(in inches) Air pressure maintained(in pounds... feet the speed of compressor may be increased 5 single strokes per minute for each 1,000 feet...

  3. 21 CFR 1250.53 - Discharge of wastes on air conveyances.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Discharge of wastes on air conveyances. 1250.53 Section 1250.53 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) REGULATIONS UNDER CERTAIN OTHER ACTS ADMINISTERED BY THE FOOD AND DRUG ADMINISTRATION...

  4. 21 CFR 1250.53 - Discharge of wastes on air conveyances.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Discharge of wastes on air conveyances. 1250.53 Section 1250.53 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) REGULATIONS UNDER CERTAIN OTHER ACTS ADMINISTERED BY THE FOOD AND DRUG ADMINISTRATION...

  5. 21 CFR 1250.53 - Discharge of wastes on air conveyances.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Discharge of wastes on air conveyances. 1250.53 Section 1250.53 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) REGULATIONS UNDER CERTAIN OTHER ACTS ADMINISTERED BY THE FOOD AND DRUG ADMINISTRATION...

  6. 21 CFR 1250.53 - Discharge of wastes on air conveyances.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Discharge of wastes on air conveyances. 1250.53 Section 1250.53 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) REGULATIONS UNDER CERTAIN OTHER ACTS ADMINISTERED BY THE FOOD AND DRUG ADMINISTRATION INTERSTATE CONVEYANCE SANITATION Equipment...

  7. 21 CFR 1250.53 - Discharge of wastes on air conveyances.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Discharge of wastes on air conveyances. 1250.53 Section 1250.53 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) REGULATIONS UNDER CERTAIN OTHER ACTS ADMINISTERED BY THE FOOD AND DRUG ADMINISTRATION INTERSTATE CONVEYANCE SANITATION Equipment...

  8. Complex utilization of snf processing wastes in air plasma of high-frequency torch discharge

    NASA Astrophysics Data System (ADS)

    Karengin, A. G.; Karengin, A. A.; Podgornaya, O. D.; Shlotgauer, E. E.

    2014-10-01

    We present results of complex spent nuclear fuel wastes utilization process in air plasma of high-frequency torch discharge in form of dispersed water-organic compositions. We demonstrate the possibility to apply magnetic separation for effective extraction of obtained dispersed solid products including magnetic iron oxide from water suspension.

  9. Effect of duty-cycles on the air plasma gas-phase of dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Barni, R.; Biganzoli, I.; Dell'Orto, E. C.; Riccardi, C.

    2015-10-01

    An experimental investigation concerning the effects of a duty-cycle in the supply of a dielectric barrier discharge in atmospheric pressure air has been performed. Electrical characteristics of the discharge have been measured, focusing mainly on the statistical properties of the current filaments and on dielectric surface charging, both affected by the frequent repetition of breakdown imposed by the duty-cycle. Information on the gas-phase composition was gathered too. In particular, a strong enhancement in the ozone formation rate is observed when suitable long pauses separate the active discharge phases. A simulation of the chemical kinetics in the gas-phase, based on a simplified discharge modeling, is briefly described in order to shed light on the observed increase in ozone production. The effect of a duty-cycle on surface modification of polymeric films in order to increase their wettability has been investigated too.

  10. A brush-shaped air plasma jet operated in glow discharge mode at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Bao, Wenting; Jia, Pengying; Di, Cong

    2014-07-01

    Using ambient air as working gas, a direct-current plasma jet is developed to generate a brush-shaped plasma plume with fairly large volume. Although a direct-current power supply is used, the discharge shows a pulsed characteristic. Based on the voltage-current curve and fast photography, the brush-shaped plume, like the gliding arc plasma, is in fact a temporal superposition of a moving discharge filament in an arched shape. During it moves away from the nozzle, the discharge evolves from a low-current arc into a normal glow in one discharge cycle. The emission profile is explained qualitatively based on the dynamics of the plasma brush.

  11. An investigation of an underwater steam plasma discharge as alternative to air plasmas for water purification

    NASA Astrophysics Data System (ADS)

    Gucker, Sarah N.; Foster, John E.; Garcia, Maria C.

    2015-10-01

    An underwater steam plasma discharge, in which water itself is the ionizing media, is investigated as a means to introduce advanced oxidation species into contaminated water for the purpose of water purification. The steam discharge avoids the acidification observed with air discharges and also avoids the need for a feed gas, simplifying the system. Steam discharge operation did not result in a pH changes in the processing of water or simulated wastewater, with the actual pH remaining roughly constant during processing. Simulated wastewater has been shown to continue to decompose significantly after steam treatment, suggesting the presence of long-lived plasma produced radicals. During steam discharge operation, nitrate production is limited, and nitrite production was found to be below the detection threshold of (roughly 0.2 mg L-1). The discharge was operated over a broad range of deposited power levels, ranging from approximately 30 W to 300 W. Hydrogen peroxide production was found to scale with increasing power. Additionally, the hydrogen peroxide production efficiency of the discharge was found to be higher than many of the rates reported in the literature to date.

  12. The influencing factors of nanosecond pulse homogeneous dielectric barrier discharge in air.

    PubMed

    Zhang, Shuai; Jia, Li; Wang, Wen-chun; Yang, De-zheng; Tang, Kai; Liu, Zhi-jie

    2014-01-01

    In this paper, a bipolar nanosecond high pulse voltage with 20 ns rising time was employed to generate homogeneous dielectric barrier discharges using the plate-plate electrode configuration in air at atmospheric pressure. The effects of pulse peak voltage, gas discharge gap, and dielectric plates made by different materials or thicknesses on the discharge homogeneity, voltage-current waveform, and optical emission spectra were investigated. Results show that aforementioned parameters have a strongly impact on the discharge homogeneity and the optical emission spectra, but it is hard to identify definitely their influences on the discharge voltage-current waveform. Homogeneous discharges were easily observed when using low permittivity dielectric plate and the emission intensity of N2 (C(3)Πu→B(3)Πg, 0-0, 337.1 nm) increases with the rising of pulse peak voltage and the permittivity of dielectric material but decreases with the increasing of gas discharge gap and the dielectric plate thickness. The rotational and vibrational temperatures (Trot and Tvib) were determined at Trot=350±5 K and Tvib=3045 K via fitting the simulative spectra of N2 (C(3)Πu→B(3)Πg, 0-2) with the measured one. PMID:24036046

  13. The influencing factors of nanosecond pulse homogeneous dielectric barrier discharge in air

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Jia, Li; Wang, Wen-chun; Yang, De-zheng; Tang, Kai; Liu, Zhi-jie

    2014-01-01

    In this paper, a bipolar nanosecond high pulse voltage with 20 ns rising time was employed to generate homogeneous dielectric barrier discharges using the plate-plate electrode configuration in air at atmospheric pressure. The effects of pulse peak voltage, gas discharge gap, and dielectric plates made by different materials or thicknesses on the discharge homogeneity, voltage-current waveform, and optical emission spectra were investigated. Results show that aforementioned parameters have a strongly impact on the discharge homogeneity and the optical emission spectra, but it is hard to identify definitely their influences on the discharge voltage-current waveform. Homogeneous discharges were easily observed when using low permittivity dielectric plate and the emission intensity of N2 (C3Πu → B3Πg, 0-0, 337.1 nm) increases with the rising of pulse peak voltage and the permittivity of dielectric material but decreases with the increasing of gas discharge gap and the dielectric plate thickness. The rotational and vibrational temperatures (Trot and Tvib) were determined at Trot = 350 ± 5 K and Tvib = 3045 K via fitting the simulative spectra of N2 (C3Πu → B3Πg, 0-2) with the measured one.

  14. Influence of Lithium Salts on the Discharge Chemistry of Li-Air Cells.

    PubMed

    Veith, Gabriel M; Nanda, Jagjit; Delmau, Laetitia H; Dudney, Nancy J

    2012-05-17

    In this work, we show that the use of a high boiling point ether solvent (tetraglyme) promotes the formation of Li2O2 in a lithium-air cell. However, another major constituent in the discharge product of a Li-air cell contains halides from the lithium salts and C-O from the tetraglyme used as the solvent. This information is critical to the development of Li-air electrolytes, which are stable and promote the formation of the desired Li2O2 products. PMID:26286765

  15. Influence of lithium salts on the discharge chemistry of Li-air cells

    SciTech Connect

    Veith, Gabriel M; Nanda, Jagjit; Delmau, Laetitia Helene; Dudney, Nancy J

    2012-01-01

    In this work we show that the use of a high boiling point ether solvent (tetraglyme) promotes the formation of Li2O2 in a lithium-air cell. In addition, another major constituent in the discharge product of a Li-air cell contains halides, from the lithium salt, and the tetraglyme used as the solvent. This information is critical to the development of Li-air electrolytes which are stable and promote the formation of the desired Li2O2 products.

  16. Study on the characteristic decomposition components of air-insulated switchgear cabinet under partial discharge

    NASA Astrophysics Data System (ADS)

    Gui, Yingang; Zhang, Xiaoxing; Zhang, Ying; Qiu, Yinjun; Chen, Lincong

    2016-07-01

    Air-insulated switchgear cabinet plays a critical role in entire power transmission and distribution system. Its stability directly affects the operational reliability of the power system. And the on-line gas detection method, which evaluates the insulation status of insulation equipment by detecting the decomposition components of filled air in cabinet, becomes an innovative way to ensure the running stability of air-insulated switchgear cabinet. In order to study the characteristic gas types and production regularity of decomposition components under partial discharge, three insulation defects: needle-plate, air-gap and impurity defect are proposed to simulate the insulation defects under partial discharge in air-insulated switchgear cabinet. Firstly, the generation pathways and mechanism of composition components are discussed. Then CO and NO2 are selected as the characteristic decomposition components to characterize the partial discharge due to their high concentration and chemical stability. Based on the different change regularity of CO and NO2 concentration under different insulation defect, it provides an effective way to evaluate and predict the insulation defect type and severity in the field.

  17. Modelling fluid flow in a reciprocating compressor

    NASA Astrophysics Data System (ADS)

    Tuhovcak, Jan; Hejčík, Jiří; Jícha, Miroslav

    2015-05-01

    Efficiency of reciprocating compressor is strongly dependent on the valves characteristics, which affects the flow through the suction and discharge line. Understanding the phenomenon inside the compressor is necessary step in development process. Commercial CFD tools offer wide capabilities to simulate the flow inside the reciprocating compressor, however they are too complicated in terms of computational time and mesh creation. Several parameters describing compressor could be therefore examined without the CFD analysis, such is valve characteristic, flow through the cycle and heat transfer. The aim of this paper is to show a numerical tool for reciprocating compressor based on the energy balance through the cycle, which provides valve characteristics, flow through the cycle and heat losses from the cylinder. Spring-damping-mass model was used for the valve description. Boundary conditions were extracted from the performance test of 4-cylinder semihermetic compressor and numerical tool validation was performed with indicated p-V diagram comparison.

  18. Effect of Electrolytes on the Decomposition of Dye by Pulsed Discharge in Air Spraying Water Droplets

    NASA Astrophysics Data System (ADS)

    Nose, Taisuke; Yokoyama, Yuzo; Minamitani, Yasushi

    Effect of electrolytes on the decolorization of indigo carmine and on the production of H2O2 by pulsed discharge in air spraying water droplets was performed in sodium chloride and magnesium sulfate solutions. Peak voltage of the discharge decreased with increasing solution conductivity, but peak current and discharge energy increased. Decolorization rate and decolorization efficiency of indigo carmine and the yield of H2O2 decreased with increasing chloride and sulfate ion concentrations. It was found that the decolorization of indigo carmine and the production of H2O2 are affected by the ion concentration even in the case of discharge in air spraying water droplets. However it was less effective than that of discharge in water. Chloride ion was more effective than sulfate ion regarding the decrease of decolorization rate and the production of H2O2. Decolorization rate of indigo carmine was strongly related to the production of H2O2. These results also indicated that decolorization of indigo carmine depends on the production of hydroxyl radical.

  19. Self-pulsing discharges in pre-heated air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Janda, Mário; Machala, Zdenko; Dvonč, Lukáš; Lacoste, Deanna; Laux, Christophe O.

    2015-01-01

    The paper presents investigations of self-pulsing discharges in atmospheric pressure air pre-heated to 300-1000 K. Despite using a direct-current power supply, two self-pulsing discharge regimes, a repetitive transient spark (TS) and a repetitive streamer (RS) were generated. The pulse repetition frequency, on the order of a few kHz, can be controlled by adjusting the generator voltage. The TS is a discharge initiated by a streamer, followed by a short (tens of ns) spark current pulse (˜ 1 A), associated with the total discharging of the internal capacity of the electric circuit. The TS is suitable for the study of ‘memory’ effects (pre-heating, pre-ionization) on the mechanisms of streamer-to-spark transition and electrical breakdown in atmospheric pressure air. The TS regime was stable below ˜600 K. Above ˜600 K, a stable repetitive streamer (RS) regime was observed. In this regime, the breakdown and spark did not occur. After the initial streamer, the internal capacity of the electrical circuit discharged partially. With further pre-heating of the gas, the stable TS appeared again at ˜1000 K.

  20. The cold and atmospheric-pressure air surface barrier discharge plasma for large-area sterilization applications

    SciTech Connect

    Wang Dacheng; Zhao Di; Feng Kecheng; Zhang Xianhui; Liu Dongping; Yang Size

    2011-04-18

    This letter reports a stable air surface barrier discharge device for large-area sterilization applications at room temperature. This design may result in visually uniform plasmas with the electrode area scaled up (or down) to the required size. A comparison for the survival rates of Escherichia coli from air, N{sub 2} and O{sub 2} surface barrier discharge plasmas is presented, and the air surface plasma consisting of strong filamentary discharges can efficiently kill Escherichia coli. Optical emission measurements indicate that reactive species such as O and OH generated in the room temperature air plasmas play a significant role in the sterilization process.

  1. Effects of air transient spark discharge and helium plasma jet on water, bacteria, cells, and biomolecules.

    PubMed

    Hensel, Karol; Kučerová, Katarína; Tarabová, Barbora; Janda, Mário; Machala, Zdenko; Sano, Kaori; Mihai, Cosmin Teodor; Ciorpac, Mitică; Gorgan, Lucian Dragos; Jijie, Roxana; Pohoata, Valentin; Topala, Ionut

    2015-01-01

    Atmospheric pressure DC-driven self-pulsing transient spark (TS) discharge operated in air and pulse-driven dielectric barrier discharge plasma jet (PJ) operated in helium in contact with water solutions were used for inducing chemical effects in water solutions, and the treatment of bacteria (Escherichia coli), mammalian cells (Vero line normal cells, HeLa line cancerous cells), deoxyribonucleic acid (dsDNA), and protein (bovine serum albumin). Two different methods of water solution supply were used in the TS: water electrode system and water spray system. The effects of both TS systems and the PJ were compared, as well as a direct exposure of the solution to the discharge with an indirect exposure to the discharge activated gas flow. The chemical analysis of water solutions was performed by using colorimetric methods of UV-VIS absorption spectrophotometry. The bactericidal effects of the discharges on bacteria were evaluated by standard microbiological plate count method. Viability, apoptosis and cell cycle were assessed in normal and cancerous cells. Viability of cells was evaluated by trypan blue exclusion test, apoptosis by Annexin V-FITC/propidium iodide assay, and cell cycle progression by propidium iodide/RNase test. The effect of the discharges on deoxyribonucleic acid and protein were evaluated by fluorescence and UV absorption spectroscopy. The results of bacterial and mammalian cell viability, apoptosis, and cell cycle clearly show that cold plasma can inactivate bacteria and selectively target cancerous cells, which is very important for possible future development of new plasma therapeutic strategies in biomedicine. The authors found that all investigated bio-effects were stronger with the air TS discharge than with the He PJ, even in indirect exposure. PMID:25947389

  2. Design features of fans, blowers, and compressors

    NASA Astrophysics Data System (ADS)

    Cheremisinoff, N. P.; Cheremisinoff, P. N.

    Fan engineering and compression machines are discussed. Basic aspects of fan performance and design are reviewed, and the design and performance characteristics of radial-flow fans, axial-flow fans, and controllable pitch fans are examined in detail. Air-conditioning systems are discussed, and noise, vibration, and mechanical considerations in fans are extensively examined. The thermodynamic principles governing compression machines are reviewed, and piston compressors, rotary compressors, blowers, and centrifugal compressors are discussed.

  3. Study on law of negative corona discharge in microparticle-air two-phase flow media

    NASA Astrophysics Data System (ADS)

    He, Bo; Li, Tianwei; Xiu, Yaping; Zhao, Heng; Peng, Zongren; Meng, Yongpeng

    2016-03-01

    To study the basic law of negative corona discharge in solid particle-air two-phase flow, corona discharge experiments in a needle-plate electrode system at different voltage levels and different wind speed were carried out in the wind tunnel. In this paper, the change law of average current and current waveform were analyzed, and the observed phenomena were systematically explained from the perspectives of airflow, particle charging, and particle motion with the help of PIV (particle image velocity) measurements and ultraviolet observations.

  4. Energy distribution of runaway electrons generated by a nanosecond discharge in atmospheric-pressure air

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Kostyrya, I. D.; Lomaev, M. I.; Petin, V. K.; Rybka, D. V.; Shlyakhtun, S. V.

    2008-12-01

    The spectra of an ultrashort avalanche electron beam generated by a nanosecond discharge in atmospheric-pressure air were investigated. The temporal characteristics of the beam current pulses, gap voltage, and discharge current in a gas diode were measured with a time resolution of ˜0.1 ns. A simple technique was developed for recovering electron spectra from the curves of beam attenuation by aluminum foils. The effect of the cathode design, electrode gap length, and generator parameters on the electron spectra were studied using seven setups. It is shown that generation of electrons with anomalously high energies requires the use of cathodes with increased curvature radius.

  5. High-speed sterilization technique using dielectric barrier discharge plasmas in atmospheric humid air

    NASA Astrophysics Data System (ADS)

    Miyamae, M.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2010-11-01

    The inactivation of Bacillus atrophaeus spores by a dielectric barrier discharge (DBD) plasma produced by an ac voltage application of 1 kHz in atmospheric humid air was investigated in order to develop low-temperature, low-cost and high-speed plasma sterilization technique. The biological indicators covered with a Tyvek sheet were set just outside the DBD plasma region, where the air temperature and humidity as a discharge gas were precisely controlled by an environmental test chamber. The results show that the inactivation of Bacillus atrophaeus spores was found to be dependent strongly on the humidity, and was completed within 15 min at a relative humidity of 90 % and a temperature of 30 C. The treatment time for sterilization is shorter than those of conventional sterilization methods using ethylene oxide gas and dry heat treatment. It is considered that reactive species such as hydroxyl radicals that are effective for the inactivation of Bacillus atrophaeus spores could be produced by the DBD plasma in the humid air. Repetitive micro-pulsed discharge plasmas in the humid air will be applied for the sterilization experiment to enhance the sterilization efficiency.

  6. Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

    NASA Astrophysics Data System (ADS)

    Uddi, M.; Jiang, N.; Adamovich, I. V.; Lempert, W. R.

    2009-04-01

    Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ~8 × 1012 cm-3 (~4.14 ppm) occurring at ~250 µs after the pulse, with decay time of ~16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of phiv = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of phiv = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N2(C 3Π) and NO(A 2Σ) in air at P = 60 Torr decay within ~20 ns and ~1 µs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (~100 µs) metastable states, such as N2(X 1Σ,v) and O2(b 1Σ), formed by quenching of the metastable N2(A 3Σ) state by ground electronic state O2, may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O2, as well as by conversion into NO2 in a reaction of NO with ozone.

  7. Centrifugal Compressors

    SciTech Connect

    Hastbacka, Mildred; Dieckmann, John; Bouza, Antonio

    2013-02-06

    The article discusses small high speed centrifugal compressors. This topic was covered in a previous ASHRAE Journal column (2003). This article reviews another configuration which has become an established product. The operation, energy savings and market potential of this offering are addressed as well.

  8. Bio-Decontamination of Water and Surfaces by DC Discharges in Atmospheric Air

    NASA Astrophysics Data System (ADS)

    Machala, Zdenko; Tarabová, Barbora; Pelach, Michal; Šipoldová, Zuzana; Hensel, Karol; Janda, Mário; Šikurová, Libuša

    Two types of DC-driven atmospheric air discharges, including a streamer corona and a transient spark with short high current pulses of limited energy, were employed for bio-decontamination of water and various surfaces (agar plates, plastic foils, human teeth) contaminated by bacteria or spores (Salmonella typhimurium, Bacillus cereus). Both discharges generate cold non-equilibrium plasma. The discharges combined with the electro-spraying of the treated water through the needle electrode lead to fast and efficient bio-decontamination. Experiments comparing direct and indirect plasma effects, oxidation stress measurements in the cell membranes, and chemical changes induced in the treated water enable assessment of the plasma agents being responsible for microbial inactivation. Radicals and reactive oxygen species seem to be dominant biocidal agents, although deeper understanding of the plasma-induced water chemistry and of the temporal evolution of the bio-inactivation processes is needed.

  9. Kinetics of NO formation and decay in nanosecond pulse discharges in Air, H2-Air, and C2H4-Air mixtures

    NASA Astrophysics Data System (ADS)

    Burnette, David; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.

    2016-04-01

    Time-resolved, absolute NO and N atom number densities are measured by NO Laser Induced Fluorescence (LIF) and N Two-Photon Absorption LIF in a diffuse plasma filament, nanosecond pulse discharge in dry air, hydrogen-air, and ethylene-air mixtures at 40 Torr, over a wide range of equivalence ratios. The results are compared with kinetic modeling calculations incorporating pulsed discharge dynamics, kinetics of vibrationally and electronically excited states of nitrogen, plasma chemical reactions, and radial transport. The results show that in air afterglow, NO decay occurs primarily by the reaction with N atoms, NO  +  N  →  N2  +  O. In the presence of hydrogen, this reaction is mitigated by reaction of N atoms with OH, N  +  OH  →  NO  +  H, resulting in significant reduction of N atom number density in the afterglow, additional NO production, and considerably higher NO number densities. In fuel-lean ethylene-air mixtures, a similar trend (i.e. N atom concentration reduction and NO number density increase) is observed, although [NO] increase on ms time scale is not as pronounced as in H2-air mixtures. In near-stoichiometric and fuel-lean ethylene-air mixtures, when N atom number density was below detection limit, NO concentration was measured to be lower than in air plasma. These results suggest that NO kinetics in hydrocarbon-air plasmas is more complex compared to air and hydrogen-air plasmas, additional NO reaction pathways may well be possible, and their analysis requires further kinetic modeling calculations.

  10. Simulation of a runaway electron avalanche developing in an atmospheric pressure air discharge

    SciTech Connect

    Oreshkin, E. V.; Barengolts, S. A.; Chaikovsky, S. A.; Oreshkin, V. I.

    2015-12-15

    To gain a better understanding of the operation of atmospheric pressure air discharges, the formation of a runaway electron beam at an individual emission site on the cathode has been numerically simulated. The model provides a description of the dynamics of the fast electrons emitted into an air gap from the surface of the emission zone by solving numerically two-dimensional equations for the electrons. It is supposed that the electric field at the surface of the emission zone is enhanced, providing conditions for continuous acceleration of the emitted electrons. It is shown that the formation of a runaway electron beam in a highly overvolted discharge is largely associated with avalanche-type processes and that the number of electrons in the avalanche reaches 50% of the total number of runaway electrons.

  11. Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

    SciTech Connect

    Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

    2014-07-07

    A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

  12. Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

    NASA Astrophysics Data System (ADS)

    Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

    2014-07-01

    A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

  13. The Effect of Air Plasma on Sterilization of Escherichia coli in Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Hu, Miao; Guo, Yun

    2012-08-01

    In this work, a Dielectric Barrier Discharge (DBD) air plasma was used to sterilize Escherichia coli (E. coli) on the surface of medical Polyethylene Terephthalate (PET) film. The leakage of cellular DNA and protein by optical absorbance measurement at 260 nm and 280 nm, together with transmission electron microscopy (TEM) about cell morphology were performed after sterilization to analyse inactivation mechanisms. The results indicated that the DBD air plasma was very effective in E. coli sterilization. The plasma germicidal efficiency depended on the plasma treatment time, the air-gap distance, and the applied voltage. Within 5 min of plasma treatment, the germicidal efficiency against E. coli could reach 99.99%. An etching action on cell membranes by electrons, ions and radicals is the primary mechanism for DBD air plasma sterilization, which leads to the effusion of cellular contents (DNA and protein) and bacterial death.

  14. Onset conditions for positive direct current corona discharges in air under the action of photoionization

    NASA Astrophysics Data System (ADS)

    Zheng, Yuesheng; Zhang, Bo; He, Jinliang

    2011-12-01

    This paper presents a numerical model for the inception of positive dc corona discharges in air near cylindrical anodes, which plays a bridge role between the classic positive corona onset criterion and the photoionization model considering the effective radiation wavelength. The predicted onset voltages agree well with Peek's experimental data in a wide range of conductor radii and relative air densities. The influence of the collisional quenching of emitting excited states on the surface onset field is significant with low air density or small conductor radius. Within the effective radiation wavelength, numerical expressions for the photon absorption coefficient in air and Townsend's second coefficient due to photoionization are deduced on the basis of the new model. A different perspective on the classic coefficients is given.

  15. Effect of plasma suppression additives on electrodynamic characteristics of the torch discharge burning in the air

    NASA Astrophysics Data System (ADS)

    Vidyaev, D.; Lutsenko, Yu; Boretsky, E.

    2016-06-01

    The paper shows the results of measurements of wave number of electromagnetic wave, which supports burning of high-frequency torch discharge in the mixture of air with water vapor and carbon dioxide. The nonmonotonic dependence of attenuation factor of electromagnetic waves is set on a concentration of water vapor. It is shown that the attenuation degree of electromagnetic field in the plasma with water vapor significantly exceeds the attenuation degree of electromagnetic field in the plasma with carbon dioxide.

  16. Cold-air performance of compressor-drive turbine of department of energy upgraded automobile gas turbine engine. 3: Performance of redesigned turbine

    NASA Technical Reports Server (NTRS)

    Roelke, R. J.; Haas, J. E.

    1984-01-01

    The aerodynamic performance of a redesigned compressor drive turbine of the gas turbine engine is determined in air at nominal inlet conditions of 325 K and 0.8 bar absolute. The turbine is designed with a lower flow factor, higher rotor reaction and a redesigned inlet volute compared to the first turbine. Comparisons between this turbine and the originally designed turbine show about 2.3 percentage points improvement in efficiency at the same rotor tip clearance. Two versions of the same rotor are tested: (1) an as cast rotor, and (2) the same rotor with reduced surface roughness. The effect of reducing surface roughness is about one half percentage point improvement in efficiency. Tests made to determine the effect of Reynolds number on the turbine performance show no effect for the range from 100,000 to 500,000.

  17. Integrated Testing of a 4-Bed Molecular Sieve and a Temperature-Swing Adsorption Compressor for Closed-Loop Air Revitalization

    NASA Technical Reports Server (NTRS)

    Knox, James C.; Mulloth, Lila M.; Affleck, David L.

    2004-01-01

    Accumulation and subsequent compression of carbon dioxide that is removed from space cabin are two important processes involved in a closed-loop air revitalization scheme of the International Space Station (ISS). The 4-Bed Molecular Sieve (4BMS) of ISS currently operates in an open loop mode without a compressor. This paper reports the integrated 4BMS and liquid-cooled TSAC testing conducted during the period of March 3 to April 18, 2003. The TSAC prototype was developed at NASA Ames Research Center (ARC). The 4BMS was modified to a functionally flight-like condition at NASA Marshall Space Flight Center (MSFC). Testing was conducted at MSFC. The paper provides details of the TSAC operation at various CO2 loadings and corresponding performance of CDRA.

  18. Investigation of nanosecond pulse dielectric barrier discharges in still air and in transonic flow by optical methods

    NASA Astrophysics Data System (ADS)

    Peschke, P.; Goekce, S.; Leyland, P.; Ott, P.

    2016-01-01

    In the present study the interaction of nanosecond pulsed dielectric barrier discharge (ns-DBD) actuators with aerodynamic flow up to transonic velocities was investigated. The primary focus was on the influence of the flow on the discharge and the effects of the discharge itself. In addition, the influence of the ns-DBD on a shock-wave was studied. The aim was to improve the understanding of the plasma-flow interaction, a topic that is not yet fully understood, in particular for ns-DBD. The actuator was integrated in two different models, a NACA 3506 compressor blade profile and a bump geometry at the bottom of the wind tunnel. The effect of the rapid energy deposition close to the discharge was examined with the phase-locked schlieren visualisation technique. Images of the plasma acquired with short exposure times revealed information on the discharge evolution. The results show a significant effect of the flow on the discharge characteristics, in particular due to the drop of static pressure. On the other hand, no significant effect of the ns-DBD on the flow was observed due to unfavourable flow conditions, which underlines the importance of the actuator’s placement.

  19. Centrifugal-reciprocating compressor

    NASA Technical Reports Server (NTRS)

    Higa, W. H. (Inventor)

    1984-01-01

    A centrifugal compressor is described which includes at least one pair of cylinders arranged in coaxial alignment and supported for angular displacement about a common axis of rotation normally disecting a common longitudinal axis of symmetry for the cylinders. The cylinders are characterized by ported closures located at the mutually remote ends thereof through which the cylinders are charged and discharged, and a pair of piston heads seated within the cylinders and supported for floating displacement in compressive strokes in response to unidirectional angular displacement imparted to the cylinders.

  20. 40 CFR 65.112 - Standards: Compressors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Standards: Compressors. 65.112 Section 65.112 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... times with an instrument reading of less than 500 parts per million. A compressor so designated...

  1. X-ray radiation from the volume discharge in atmospheric-pressure air

    NASA Astrophysics Data System (ADS)

    Bratchikov, V. B.; Gagarinov, K. A.; Kostyrya, I. D.; Tarasenko, V. F.; Tkachev, A. N.; Yakovlenko, S. I.

    2007-07-01

    X-ray radiation from the volume discharge in atmospheric-pressure air is studied under the conditions when the voltage pulse rise time varies from 0.5 to 100 ns and the open-circuit voltage amplitude of the generator varies from 20 to 750 kV. It is shown that a volume discharge from a needle-like cathode forms at a relatively wide voltage pulse (to ≈60 ns in this work). The volume character of the discharge is due to preionization by fast electrons, which arise when the electric field concentrates at the cathode and in the discharge gap. As the voltage pulse rise time grows, X-ray radiation comes largely from the discharge gap in accordance with previous experiments. Propagation of fast avalanche electrons in nitrogen subjected to a nonuniform unsteady electric field is simulated. It is demonstrated that the amount of hard X-ray photons grows not only with increasing voltage amplitude but also with shortening pulse rise time.

  2. Laser electric field measurement in open-air dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Ito, Tsuyohito; Kanazawa, Tatsuya; Hamaguchi, Satoshi

    2011-10-01

    Electric field induced coherent Raman scattering (E-CRS) measurement is a promising technique for measuring electric field in high-pressure environments. In this study, the discharge initiation mechanism of nanosecond dielectric barrier discharges (DBDs) in open air has been examined with time dependent measurement of the discharge electric field by E-CRS. Two pulsed ns laser beams (532 nm and 607 nm) are employed. In the presence of nitrogen molecules the two laser beams together with the electric field induce a coherent IR signal at a wavelength of 4.29 μm and the normal coherent anti-Stokes Raman scattering (CARS) signal at 473 nm. The ratio of these two signals (IR and CARS) is a function of the electric field strength, so that the magnitude of the electric field can be estimated. Our experimental observations have revealed that, in the pre-breakdown phase of a nanosecond DBD discharge, the externally applied fast-rising electric field is strongly enhanced near the cathode due to large accumulation of space charge, which then strongly enhances ionization near the cathode. This process is essentially different from the well-known Townsend mechanism for slower discharges.

  3. Hydride compressor

    DOEpatents

    Powell, James R.; Salzano, Francis J.

    1978-01-01

    Method of producing high energy pressurized gas working fluid power from a low energy, low temperature heat source, wherein the compression energy is gained by using the low energy heat source to desorb hydrogen gas from a metal hydride bed and the desorbed hydrogen for producing power is recycled to the bed, where it is re-adsorbed, with the recycling being powered by the low energy heat source. In one embodiment, the adsorption-desorption cycle provides a chemical compressor that is powered by the low energy heat source, and the compressor is connected to a regenerative gas turbine having a high energy, high temperature heat source with the recycling being powered by the low energy heat source.

  4. Supersonic compressor

    DOEpatents

    Lawlor, Shawn P.; Novaresi, Mark A.; Cornelius, Charles C.

    2008-02-26

    A gas compressor based on the use of a driven rotor having an axially oriented compression ramp traveling at a local supersonic inlet velocity (based on the combination of inlet gas velocity and tangential speed of the ramp) which forms a supersonic shockwave axially, between adjacent strakes. In using this method to compress inlet gas, the supersonic compressor efficiently achieves high compression ratios while utilizing a compact, stabilized gasdynamic flow path. Operated at supersonic speeds, the inlet stabilizes an oblique/normal shock system in the gasdyanamic flow path formed between the gas compression ramp on a strake, the shock capture lip on the adjacent strake, and captures the resultant pressure within the stationary external housing while providing a diffuser downstream of the compression ramp.

  5. Compressor surge prevention

    SciTech Connect

    McLeister, L.

    1995-09-01

    One of the more difficult challenges facing compressor and control engineers is designing compressor control and anti-surge packages that maximize efficiency while maintaining safe compressor operating conditions. This paper focuses specifically on centrifugal compressor anti-surge philosophies. The conditions that precipitate surge in centrifugal compressors will be explored along with risk reduction techniques. Axial and reciprocating compressors have slightly different characteristics and are topics for another discussion.

  6. Nanosecond repetitively pulsed discharges in air at atmospheric pressure—the spark regime

    NASA Astrophysics Data System (ADS)

    Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-12-01

    Nanosecond repetitively pulsed (NRP) spark discharges have been studied in atmospheric pressure air preheated to 1000 K. Measurements of spark initiation and stability, plasma dynamics, gas temperature and current-voltage characteristics of the spark regime are presented. Using 10 ns pulses applied repetitively at 30 kHz, we find that 2-400 pulses are required to initiate the spark, depending on the applied voltage. Furthermore, about 30-50 pulses are required for the spark discharge to reach steady state, following initiation. Based on space- and time-resolved optical emission spectroscopy, the spark discharge in steady state is found to ignite homogeneously in the discharge gap, without evidence of an initial streamer. Using measured emission from the N2 (C-B) 0-0 band, it is found that the gas temperature rises by several thousand Kelvin in the span of about 30 ns following the application of the high-voltage pulse. Current-voltage measurements show that up to 20-40 A of conduction current is generated, which corresponds to an electron number density of up to 1015 cm-3 towards the end of the high-voltage pulse. The discharge dynamics, gas temperature and electron number density are consistent with a streamer-less spark that develops homogeneously through avalanche ionization in volume. This occurs because the pre-ionization electron number density of about 1011 cm-3 produced by the high frequency train of pulses is above the critical density for streamer-less discharge development, which is shown to be about 108 cm-3.

  7. Study of flow fields induced by surface dielectric barrier discharge actuator in low-pressure air

    SciTech Connect

    Che, Xueke E-mail: st@mail.iee.ac.cn; Nie, Wansheng; Tian, Xihui; Hou, Zhiyong; He, Haobo; Zhou, Penghui; Zhou, Siyin; Yang, Chao; Shao, Tao E-mail: st@mail.iee.ac.cn

    2014-04-15

    Surface dielectric barrier discharge (SDBD) is a promising method for a flow control. Flow fields induced by a SDBD actuator driven by the ac voltage in static air at low pressures varying from 1.0 to 27.7 kPa are measured by the particle image velocimetry method. The influence of the applied ac voltage frequency and magnitude on the induced flow fields is studied. The results show that three different classes of flow fields (wall jet flow field, complex flow field, and vortex-shape flow field) can be induced by the SDBD actuator in the low-pressure air. Among them, the wall jet flow field is the same as the tangential jet at atmospheric pressure, which is, together with the vertical jet, the complex flow field. The vortex-shape flow field is composed of one vertical jet which points towards the wall and two opposite tangential jets. The complex and the vortex-shape flow fields can be transformed to the wall jet flow field when the applied ac voltage frequency and magnitude are changed. It is found that the discharge power consumption increases initially, decreases, and then increases again at the same applied ac voltage magnitude when the air pressure decreases. The tangential velocity of the wall jet flow field increases when the air pressure decreases. It is however opposite for the complex flow field. The variation of the applied ac voltage frequency influences differently three different flow fields. When the applied ac voltage magnitude increases at the same applied ac voltage frequency, the maximal jet velocity increases, while the power efficiency increases only initially and then decreases again. The discharge power shows either linear or exponential dependences on the applied ac voltage magnitude.

  8. Computational Study of the Hydrodynamic Behavior during Air Discharge through a Sparger Submerged in the Condensation Pool

    SciTech Connect

    Ahn, Hyung-Joon; Bang, Young-Seok; Kim, In-Goo; Kim, Hho-Jung; Lee, Byeong-Eun; Kwon, Soon-Bum

    2002-07-01

    The In-containment Refueling Water Storage Tank (IRWST) has the function of heat sink when steam is released from the pressurizer. The hydrodynamic behaviors occurring at the sparger are very complex because of the wide variety of operating conditions and the complex geometry. Hydrodynamic behavior when air is discharged through a sparger in a condensation pool is investigated using CFD techniques in the present study. The effect of pressure acting on the sparger header during both water and air discharge through the sparger is studied. In addition, pressure oscillation occurring during air discharge through the sparger is studied for a better understanding of mechanisms of air discharge and a better design of the IRWST, including sparger. (authors)

  9. Nanoparticle formation by laser ablation in air and by spark discharges at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Itina, T. E.; Voloshko, A.

    2013-12-01

    Recent promising methods of nanoparticle fabrication include laser ablation and spark discharge. Despite different experimental conditions, a striking similarity is often observed in the sizes of the obtained particles. To explain this result, we elucidate physical mechanisms involved in the formation of metallic nanoparticles. In particular, we compare supersaturation degree and sizes of critical nucleus obtained under laser ablation conditions with that obtained for spark discharge in air. For this, the dynamics of the expansion of either ablated or eroded products is described by using a three-dimensional blast wave model. Firstly, we consider nanosecond laser ablation in air. In the presence of a background gas, the plume expansion is limited by the gas pressure. Nanoparticles are mostly formed by nucleation and condensation taking place in the supersaturated vapor. Secondly, we investigate nanoparticles formation by spark discharge at atmospheric pressure. After efficient photoionization and streamer expansion, the cathode material suffers erosion and NPs appear. The calculation results allow us to examine the sizes of critical nuclei as function of the experimental parameters and to reveal the conditions favorable for the size reduction and for the increase in the nanoparticle yield.

  10. Sub-nanosecond dynamics of atmospheric air discharge under highly inhomogeneous and transient electric field

    NASA Astrophysics Data System (ADS)

    Tardiveau, Pierre; Magne, Lionel; Pasquiers, Stephane; Jeanney, Pascal; Bournonville, Blandine

    2015-09-01

    The effects of the application of extreme overvoltages (>500%) in air gaps over less than a few nanoseconds bring us to reconsider the classical physics of streamer used to describe air discharges at atmospheric pressure. Non equilibrium discharges created by extremely transient and intense electric fields in standard conditions of pressure and temperature exhibit unusual diffuse and large structure. In point-to-plane electrode configurations, a plasma cloud is observed which properties depend on voltage pulses features (amplitude, rise time, length, and frequency) and electrodes properties (material, shape, and gap length). Our parametric experimental study is based on fast electrical characterization and sub-nanosecond imaging and shows the different stages of propagation of the cloud. This work details the conditions to maximize the cloud size without moving towards a multi-channel streamer regime. Based on the analysis and the Abel transform processing of the emission of excited states of nitrogen from the discharge, a focus is made on the structuration of the plasma cloud while it is propagating. It shows how much, according to the experimental conditions, the external electric field can be screened by the plasma and, inversely, how deep and how long a high electric field can be sustained in the gap, that is challenging for pulsed atmospheric plasmas applications. This work benefits from the financial support of the National Agency of Research within the framework of the project ANR-13-BS09-0014.

  11. Experimental study of the spatio-temporal development of metre-scale negative discharge in air

    NASA Astrophysics Data System (ADS)

    Kochkin, P. O.; van Deursen, A. P. J.; Ebert, U.

    2014-04-01

    We study the development of a negative discharge of about 1 MV driven by a Marx generator in an air gap of 1-1.5 m, at standard temperature and pressure. We show the evolution of the discharge with nanosecond-fast photography together with the electrical characteristics. The negative discharge develops through four well-distinguished streamer bursts. The streamers have different velocities and life times in different bursts. The last burst triggers a positive inception cloud on the positive grounded electrode and a burst of positive counter-streamers emerge. The pre-discharge then bridges the gap and leaders grow from both electrodes. Finally a spark is formed. Looking closer into the pre-ionized zone near the cathode, we find isolated dots which are potential branching points. These dots act as starting points for positive streamers that move toward the high-voltage electrode. We also find phenomena such as space leaders and leader stepping in our laboratory sparks.

  12. Generating diffuse discharge via repetitive nanosecond pulses and line-line electrodes in atmospheric air.

    PubMed

    Li, Lee; Liu, Yun-Long; Ge, Ya-Feng; Bin, Yu; Huang, Jia-Jia; Lin, Fo-Chan

    2013-10-01

    Diffuse discharge in atmospheric air can generate extremely high power density and large-scale non-thermal plasma. An achievable method of generating diffuse discharge is reported in this paper. Based on the resonance theory, a compact high-voltage repetitive nanosecond pulse generator (HRNPG) has been developed as discharge excitation source. The HRNPG mainly consists of repetitive charging circuit, Tesla transformer and sharpening switch. With the voltage lower than 1.0 kV, the primary repetitive charging circuit comprises two fast thyristors as low-voltage switches. A spiral Tesla transformer is designed to provide a peak transformation ratio of more than 100. The HRNPG prototype is capable of generating a pulse with over 100 kV peak voltage and ~30 ns rise-time at the repetition frequency of 500 Hz. Using the copper line electrodes with a diameter of 0.4 mm, the gaps with highly non-uniform electric field are structured. With the suitable gap spacing and applied pulse, the glow-like diffuse discharge has been generated in line-type and ring-type electrode pairs. Some typical images are presented. PMID:24182161

  13. Nanosecond Repetitively Pulsed Discharges in Air at Atmospheric Pressure -- Experiment and Theory of Regime Transitions

    NASA Astrophysics Data System (ADS)

    Pai, David; Lacoste, Deanna; Laux, Christophe

    2009-10-01

    In atmospheric pressure air preheated from 300 to 1000 K, the Nanosecond Repetitively Pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and inter-electrode gap distance) of each discharge regime. Notably, there is a minimum gap distance for the existence of the glow regime that increases with decreasing gas temperature. A theory is developed to describe the Corona-to-Glow (C-G) and Glow-to-Spark (G-S) transitions for NRP discharges. The C-G transition is shown to depend on the Avalanche-to-Streamer Transition (AST) as well as the electric field strength in the positive column. The G-S transition is due to the thermal ionization instability. The minimum gap distance for the existence of the glow regime can be understood by considering that the applied voltage of the AST must be lower than that of the thermal ionization instability. This is a previously unknown criterion for generating glow discharges, as it does not correspond to the Paschen minimum or to the Meek-Raether criterion.

  14. Generating diffuse discharge via repetitive nanosecond pulses and line-line electrodes in atmospheric air

    NASA Astrophysics Data System (ADS)

    Li, Lee; Liu, Yun-Long; Ge, Ya-Feng; Bin, Yu; Huang, Jia-Jia; Lin, Fo-Chan

    2013-10-01

    Diffuse discharge in atmospheric air can generate extremely high power density and large-scale non-thermal plasma. An achievable method of generating diffuse discharge is reported in this paper. Based on the resonance theory, a compact high-voltage repetitive nanosecond pulse generator (HRNPG) has been developed as discharge excitation source. The HRNPG mainly consists of repetitive charging circuit, Tesla transformer and sharpening switch. With the voltage lower than 1.0 kV, the primary repetitive charging circuit comprises two fast thyristors as low-voltage switches. A spiral Tesla transformer is designed to provide a peak transformation ratio of more than 100. The HRNPG prototype is capable of generating a pulse with over 100 kV peak voltage and ˜30 ns rise-time at the repetition frequency of 500 Hz. Using the copper line electrodes with a diameter of 0.4 mm, the gaps with highly non-uniform electric field are structured. With the suitable gap spacing and applied pulse, the glow-like diffuse discharge has been generated in line-type and ring-type electrode pairs. Some typical images are presented.

  15. Current-voltage characteristics of dc corona discharges in air between coaxial cylinders

    NASA Astrophysics Data System (ADS)

    Zheng, Yuesheng; Zhang, Bo; He, Jinliang

    2015-02-01

    This paper presents the experimental measurement and numerical analysis of the current-voltage characteristics of dc corona discharges in air between coaxial cylinders. The current-voltage characteristics for both positive and negative corona discharges were measured within a specially designed corona cage. Then the measured results were fitted by different empirical formulae and analyzed by the fluid model. The current-voltage characteristics between coaxial cylinders can be expressed as I = C(U - U0)m, where m is within the range 1.5-2.0, which is similar to the point-plane electrode system. The ionization region has no significant effect on the current-voltage characteristic under a low corona current, while it will affect the distribution for the negative corona under a high corona current. The surface onset fields and ion mobilities were emphatically discussed.

  16. Streptococci biofilm decontamination on teeth by low-temperature air plasma of dc corona discharges

    NASA Astrophysics Data System (ADS)

    Kovalóvá, Z.; Zahoran, M.; Zahoranová, A.; Machala, Z.

    2014-06-01

    Non-thermal plasmas of atmospheric pressure air direct current corona discharges were investigated for potential applications in dental medicine. The objective of this ex vivo study was to apply cold plasmas for the decontamination of Streptococci biofilm grown on extracted human teeth, and to estimate their antimicrobial efficiency and the plasma's impact on the enamel and dentine of the treated tooth surfaces. The results show that both positive streamer and negative Trichel pulse coronas can reduce bacterial population in the biofilm by up to 3 logs in a 10 min exposure time. This bactericidal effect can be reached faster (within 5 min) by electrostatic spraying of water through the discharge onto the treated tooth surface. Examination of the tooth surface after plasma exposure by infrared spectroscopy and scanning electron microscopy did not show any significant alteration in the tooth material composition or the tooth surface structures.

  17. Dimensional analysis of detrimental ozone generation by positive wire-to-plate corona discharge in air

    NASA Astrophysics Data System (ADS)

    Bo, Z.; Chen, J. H.

    2010-02-01

    The dimensional analysis technique is used to formulate a correlation between ozone generation rate and various parameters that are important in the design and operation of positive wire-to-plate corona discharges in indoor air. The dimensionless relation is determined by linear regression analysis based on the results from 36 laboratory-scale experiments. The derived equation is validated by experimental data and a numerical model published in the literature. Applications of such derived equation are illustrated through an example selection of the appropriate set of operating conditions in the design/operation of a photocopier to follow the federal regulations of ozone emission. Finally, a new current-voltage characteristic equation is proposed for positive wire-to-plate corona discharges based on the derived dimensionless equation.

  18. Current-voltage characteristics of dc corona discharges in air between coaxial cylinders

    SciTech Connect

    Zheng, Yuesheng; Zhang, Bo He, Jinliang

    2015-02-15

    This paper presents the experimental measurement and numerical analysis of the current-voltage characteristics of dc corona discharges in air between coaxial cylinders. The current-voltage characteristics for both positive and negative corona discharges were measured within a specially designed corona cage. Then the measured results were fitted by different empirical formulae and analyzed by the fluid model. The current-voltage characteristics between coaxial cylinders can be expressed as I = C(U − U{sub 0}){sup m}, where m is within the range 1.5–2.0, which is similar to the point-plane electrode system. The ionization region has no significant effect on the current-voltage characteristic under a low corona current, while it will affect the distribution for the negative corona under a high corona current. The surface onset fields and ion mobilities were emphatically discussed.

  19. The inception of pulsed discharges in air: simulations in background fields above and below breakdown

    NASA Astrophysics Data System (ADS)

    Sun, Anbang; Teunissen, Jannis; Ebert, Ute

    2014-11-01

    We investigate discharge inception in air, in uniform background electric fields above and below the breakdown threshold. We perform 3D particle simulations that include a natural level of background ionization in the form of positive and \\text{O}2- ions. In background fields below breakdown, we use a strongly ionized seed of electrons and positive ions to enhance the field locally. In the region of enhanced field, we observe the growth of positive streamers, as in previous simulations with 2D plasma fluid models. The inclusion of background ionization has little effect in this case. When the background field is above the breakdown threshold, the situation is very different. Electrons can then detach from \\text{O}2- and start ionization avalanches in the whole volume. These avalanches together create one extended discharge, in contrast to the ‘double-headed’ streamers found in many fluid simulations.

  20. Laser-induced fluorescence from N2(+) ions generated by a corona discharge in ambient air.

    PubMed

    Konthasinghe, Kumarasiri; Fitzmorris, Kristin; Peiris, Manoj; Hopkins, Adam J; Petrak, Benjamin; Killinger, Dennis K; Muller, Andreas

    2015-09-01

    In this work, we present the measurement of laser-induced fluorescence from N2(+) ions via the B(2)Σu(+)-X(2)Σg(+) band system in the near-ultraviolet. The ions were generated continuously by a plasma glow discharge in low pressure N2 and by a corona discharge in ambient air. The fluorescence decay time was found to rapidly decrease with increasing pressure leading to an extrapolated decay rate of ≍10(10) s(-1) at atmospheric pressure. In spite of this quenching, we were able to observe laser induced fluorescence in ambient air by means of a time-gated spectral measurement. In the process of comparing the emission signal with that of N2 spontaneous Raman scattering, ion concentrations in ambient air of order 10(8-)10(10) cm(-3) were determined. With moderate increases in laser power and collection efficiency, ion concentrations of less than 10(6) cm(-3) may be measurable, potentially enabling applications in atmospheric standoff detection of ionizing radiation from hazardous radioactive sources. PMID:26414524

  1. Electron density measurements in a pulse-repetitive microwave discharge in air

    SciTech Connect

    Nikolic, M.; Popovic, S.; Vuskovic, L.; Herring, G. C.; Exton, R. J.

    2011-12-01

    We have developed a technique for absolute measurements of electron density in pulse-repetitive microwave discharges in air. The technique is based on the time-resolved absolute intensity of a nitrogen spectral band belonging to the Second Positive System, the kinetic model and the detailed particle balance of the N{sub 2}C{sup 3}{Pi}{sub u} ({nu} = 0) state. This new approach bridges the gap between two existing electron density measurement methods (Langmuir probe and Stark broadening). The electron density is obtained from the time-dependent rate equation for the population of N{sub 2}C{sup 3}{Pi}{sub u} ({nu} = 0) using recorded waveforms of the absolute C{sup 3}{Pi}{sub u}{yields}B{sup 3}{Pi}{sub g} (0-0) band intensity, the forward and reflected microwave power density. Measured electron density waveforms using numerical and approximated analytical methods are presented for the case of pulse repetitive planar surface microwave discharge at the aperture of a horn antenna covered with alumina ceramic plate. The discharge was generated in air at 11.8 Torr with a X-band microwave generator using 3.5 {mu}s microwave pulses at peak power of 210 kW. In this case, we were able to time resolve the electron density within a single 3.5 {mu}s pulse. We obtained (9.0 {+-} 0.6) x 10{sup 13} cm{sup -3} for the peak and (5.0 {+-} 0.6) x 10{sup 13} cm{sup -3} for the pulse-average electron density. The technique presents a convenient, non-intrusive diagnostic method for local, time-defined measurements of electron density in short duration discharges near atmospheric pressures.

  2. Extended plasma channels created by UV laser in air and their application to control electric discharges

    SciTech Connect

    Zvorykin, V. D. Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, I. V.; Ustinovskii, N. N.; Shutov, A. V.

    2015-02-15

    Results are presented from a series of experimental and theoretical studies on creating weakly ionized extended plasma channels in atmospheric air by 248-nm UV laser radiation and their application to control long high-voltage discharges. The main mechanisms of air ionization by UV laser pulses with durations from 100 fs to 25 ns and intensities in the ranges of 3×10{sup 11}–1.5×10{sup 13} and 3×10{sup 6}–3×10{sup 11} W/cm{sup 2}, respectively, which are below the threshold for optical gas breakdown, as well as the main relaxation processes in plasma with a density of 10{sup 9}–10{sup 17} cm{sup −3}, are considered. It is shown that plasma channels in air can be efficiently created by amplitude-modulated UV pulses consisting of a train of subpicosecond pulses producing primary photoelectrons and a long UV pulse suppressing electron attachment and sustaining the density of free electrons in plasma. Different modes of the generation and amplification of trains of subterawatt subpicosecond pulses and amplitude-modulated UV pulses with an energy of several tens of joules were implemented on the GARPUN-MTW hybrid Ti:sapphire-KrF laser facility. The filamentation of such UV laser beams during their propagation in air over distances of up to 100 m and the parameters of the corresponding plasma channels were studied experimentally and theoretically. Laser initiation of high-voltage electric discharges and control of their trajectories by means of amplitude-modulated UV pulses, as well as the spatiotemporal structure of breakdowns in air gaps with length of up to 80 cm, were studied.

  3. Influence of surface emission processes on a fast-pulsed dielectric barrier discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Pechereau, François; Bonaventura, Zdeněk; Bourdon, Anne

    2016-08-01

    This paper presents simulations of an atmospheric pressure air discharge in a point-to-plane geometry with a dielectric layer parallel to the cathode plane. Experimentally, a discharge reignition in the air gap below the dielectrics has been observed. With a 2D fluid model, it is shown that due to the fast rise of the high voltage applied and the sharp point used, a first positive spherical discharge forms around the point. Then this discharge propagates axially and impacts the dielectrics. As the first discharge starts spreading on the upper dielectric surface, in the second air gap with a low preionization density of {{10}4}~\\text{c}{{\\text{m}}-3} , the 2D fluid model predicts a rapid reignition of a positive discharge. As in experiments, the discharge reignition is much slower, a discussion on physical processes to be considered in the model to increase the reignition delay is presented. The limit case with no initial seed charges in the second air gap has been studied. First, we have calculated the time to release an electron from the cathode surface by thermionic and field emission processes for a work function φ \\in ≤ft[3,4\\right] eV and an amplification factor β \\in ≤ft[100,220\\right] . Then a 3D Monte Carlo model has been used to follow the dynamics of formation of an avalanche starting from a single electron emitted at the cathode. Due to the high electric field in the second air gap, we have shown that in a few nanoseconds, a Gaussian cloud of seed charges is formed at a small distance from the cathode plane. This Gaussian cloud has been used as the initial condition of the 2D fluid model in the second air gap. In this case, the propagation of a double headed discharge in the second air gap has been observed and the reignition delay is in rather good agreement with experiments.

  4. Honeycomb superlattice pattern in a dielectric barrier discharge in argon/air

    SciTech Connect

    Zhu, Ping; Dong, Lifang Yang, Jing; Gao, Yenan; Wang, Yongjie; Li, Ben

    2015-02-15

    We report on a honeycomb superlattice pattern in a dielectric barrier discharge in argon/air for the first time. It consists of hexagon lattice and honeycomb framework and bifurcates from a hexagon pattern as the applied voltage increases. A phase diagram of the pattern as a function of the gas component and gas pressure is presented. The instantaneous images show that the hexagon lattice and honeycomb framework are ignited in turn in each half voltage cycle. The honeycomb framework is composed of filaments ignited randomly. The spatiotemporal dynamics of honeycomb superlattice pattern is discussed by wall charges.

  5. Genetic effects of an air discharge plasma on Staphylococcus aureus at the gene transcription level

    NASA Astrophysics Data System (ADS)

    Xu, Zimu; Wei, Jun; Shen, Jie; Liu, Yuan; Ma, Ronghua; Zhang, Zelong; Qian, Shulou; Ma, Jie; Lan, Yan; Zhang, Hao; Zhao, Ying; Xia, Weidong; Sun, Qiang; Cheng, Cheng; Chu, Paul K.

    2015-05-01

    The dynamics of gene expression regulation (at transcription level) in Staphylococcus aureus after different doses of atmospheric-pressure room-temperature air plasma treatments are investigated by monitoring the quantitative real-time polymerase chain reaction. The plasma treatment influences the transcription of genes which are associated with several important bio-molecular processes related to the environmental stress resistance of the bacteria, including oxidative stress response, biofilm formation, antibiotics resistance, and DNA damage protection/repair. The reactive species generated by the plasma discharge in the gas phase and/or induced in the liquid phase may account for these gene expression changes.

  6. Experimental investigation on large-area dielectric barrier discharge in atmospheric nitrogen and air assisted by the ultraviolet lamp.

    PubMed

    Zhang, Yan; Gu, Biao; Wang, Wenchun; Wang, Dezhen; Peng, Xuwen

    2009-04-01

    In this paper, ultraviolet radiation produced by the ultraviolet lamp is employed to supply pre-ionization for the dielectric barrier discharge in N(2) or air at atmospheric pressure. The effect of the ultraviolet pre-ionization on improving the uniformity of the dielectric barrier discharge is investigated experimentally. The atmospheric pressure glow discharge of the large area (270 mm x 120 mm) is obtained successfully via the ultraviolet pre-ionization in atmospheric DBD in N(2) when the gas gap decrease to 3mm. Based on the emission spectra, the mechanism which ultraviolet pre-ionization improves the uniformity of the dielectric barrier discharge is discussed. PMID:19129005

  7. Analyzing x-ray emissions from meter-scale negative discharges in ambient air

    NASA Astrophysics Data System (ADS)

    Kochkin, Pavlo; Köhn, Christoph; Ebert, Ute; van Deursen, Lex

    2016-08-01

    When voltage pulses of 1 MV drive meter long air discharges, short and intense bursts of x-rays are measured. Here we develop a model for electron acceleration and subsequent photon generation within this discharge to understand these bursts. We start from the observation that the encounter of two streamers of opposite polarity launches the electrons, that they are further accelerated in the discharge field and then lose their energy, e.g., by photon emission through Bremsstrahlung. We model electron and photon dynamics in space and energy with a Monte Carlo model. Also the detector response to incoming photons is modelled in detail. The model justifies the approximation that the x-ray bursts are isotropic in space; this assumption is used to conclude that x-ray bursts near the high-voltage electrode with 6\\centerdot {{10}4} photons and characteristic energies of 160 keV closely reproduce the measured spectra and attenuation curves. The nanosecond duration of the bursts as well as their energy spectrum is consistent with model calculations.

  8. Stress response of Escherichia coli induced by surface streamer discharge in humid air

    NASA Astrophysics Data System (ADS)

    Doležalová, Eva; Prukner, Václav; Lukeš, Petr; Šimek, Milan

    2016-02-01

    Inactivation of Escherichia coli by means of surface streamer discharge has been investigated to obtain new insights into the key mechanisms involved, with a particular emphasis placed on the microbial response to plasma-induced stress. The surface streamer discharge was produced in coplanar dielectric barrier discharge electrode geometry, and was driven by an amplitude-modulated ac high voltage in humid synthetic air at atmospheric pressure. The response to plasma-induced stress was evaluated by using conventional cultivation, sublethal injury and resazurin assay and the LIVE/DEAD® BacLight™ Bacterial Viability kit. Compared to conventional cultivation, the LIVE/DEAD® test labels bacteria with damaged membranes, while resazurin assay tracks their metabolic activity. Our results clearly demonstrate that the treated bacteria partly lost their ability to grow properly, i.e. they became injured and culturable, or even viable but nonculturable (VBNC). The ability to develop colonies could have been lost due to damage of the bacterial membrane. Damage of the membranes was mainly caused by the lipid peroxidation, evidencing the key role of oxygen reactive species, in particular ozone. We conclude that the conventional cultivation method overestimates the decontamination efficiency of various plasma sources, and must therefore be complemented by alternative techniques capable of resolving viable but nonculturable bacteria.

  9. Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air

    NASA Astrophysics Data System (ADS)

    Reece Roth, J.

    2004-11-01

    The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering

  10. Mortality of inshore marine mammals in eastern Australia is predicted by freshwater discharge and air temperature.

    PubMed

    Meager, Justin J; Limpus, Colin

    2014-01-01

    Understanding environmental and climatic drivers of natural mortality of marine mammals is critical for managing populations effectively and for predicting responses to climate change. Here we use a 17-year dataset to demonstrate a clear relationship between environmental forcing and natural mortality of inshore marine mammals across a subtropical-tropical coastline spanning a latitudinal gradient of 13° (>2000 km of coastline). Peak mortality of inshore dolphins and dugongs followed sustained periods of elevated freshwater discharge (9 months) and low air temperature (3 months). At a regional scale, these results translated into a strong relationship between annual mortality and an index of El Niño-Southern Oscillation. The number of cyclones crossing the coastline had a comparatively weak effect on inshore marine mammal mortality, and only in the tropics. Natural mortality of offshore/migratory cetaceans was not predicted by freshwater discharge, but was related to lagged air temperature. These results represent the first quantitative link between environmental forcing and marine mammal mortality in the tropics, and form the basis of a predictive tool for managers to prepare responses to periods of elevated marine mammal mortality. PMID:24740149

  11. Field demonstration and commercialization of silent discharge plasma hazardous air pollutant control technology

    SciTech Connect

    Rosocha, L.A.; Coogan, J.J.; Korzekwa, R.A.; Secker, D.A.; Reimers, R.F.; Herrmann, P.G.; Chase, P.J.; Gross, M.P. |; Jones, M.R.

    1996-07-01

    Silent electrical discharge plasma (dielectric barrier) reactors can decompose gas-phase pollutants by free-radical attack or electron-induced fragmentation. The radicals or electrons are produced by the large average volume nonthermal plasmas generated in the reactor. In the past decade, the barrier configuration has attracted attention for destroying toxic chemical agents for the military, removing harmful greenhouse gases, and treating other environmentally- hazardous chemical compounds. At the Los Alamos National Laboratory, we have been studying the silent discharge plasma (SDP) for processing gaseous-based hazardous chemicals for approximately five years. The key objective is to convert hazardous or toxic chemicals into non-hazardous compounds or into materials which are more easily managed. The main applications have been for treating off-gases from thermal treatment units, and for abating hazardous air-pollutant emissions (e.g., industrial air emissions, vapors extracted from contaminated soil or groundwater). In this paper, we will summarize the basic principles of SDP processing, discuss illustrative applications of the technology, and present results from small-scale field tests that are relevant to our commercialization effort.

  12. Mortality of Inshore Marine Mammals in Eastern Australia Is Predicted by Freshwater Discharge and Air Temperature

    PubMed Central

    Meager, Justin J.; Limpus, Colin

    2014-01-01

    Understanding environmental and climatic drivers of natural mortality of marine mammals is critical for managing populations effectively and for predicting responses to climate change. Here we use a 17-year dataset to demonstrate a clear relationship between environmental forcing and natural mortality of inshore marine mammals across a subtropical-tropical coastline spanning a latitudinal gradient of 13° (>2000 km of coastline). Peak mortality of inshore dolphins and dugongs followed sustained periods of elevated freshwater discharge (9 months) and low air temperature (3 months). At a regional scale, these results translated into a strong relationship between annual mortality and an index of El Niño-Southern Oscillation. The number of cyclones crossing the coastline had a comparatively weak effect on inshore marine mammal mortality, and only in the tropics. Natural mortality of offshore/migratory cetaceans was not predicted by freshwater discharge, but was related to lagged air temperature. These results represent the first quantitative link between environmental forcing and marine mammal mortality in the tropics, and form the basis of a predictive tool for managers to prepare responses to periods of elevated marine mammal mortality. PMID:24740149

  13. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways

    NASA Astrophysics Data System (ADS)

    Liu, D. X.; Liu, Z. C.; Chen, C.; Yang, A. J.; Li, D.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2016-04-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2‑ and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios.

  14. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways.

    PubMed

    Liu, D X; Liu, Z C; Chen, C; Yang, A J; Li, D; Rong, M Z; Chen, H L; Kong, M G

    2016-01-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H(+), nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2(-) and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios. PMID:27033381

  15. Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways

    PubMed Central

    Liu, D. X.; Liu, Z. C.; Chen, C.; Yang, A. J.; Li, D.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2016-01-01

    Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2− and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios. PMID:27033381

  16. OMC Compressor Case

    NASA Technical Reports Server (NTRS)

    Humphrey, W. Donald

    1997-01-01

    This report summarizes efforts expended in the development of an all-composite compressor case. Two pre-production units have been built, one utilizing V-CAP and one utilizing AFR-700B resin systems. Both units have been rig tested at elevated temperatures well above design limit loads. This report discusses the manufacturing processes, test results, and Finite Element Analysis performed. The V-CAP unit was funded by NASA-Lewis Research Center in 1994 under contract number NAS3- 27442 for Development of an All-Composite OMC Compressor Case. This contract was followed by an Air Force study in 1996 to build and identical unit using the AFR-700B resin system in place of the V-CAP system. The second compressor case was funded under U.S. Air Force contract F33615-93-D-5326, Advanced Materials for Aerospace Structures Special Studies (AMAS3), Delivery Order 0021 entitled "Advanced Polymeric Composite Materials and Structures Technology for Advanced High Temperature Gas Turbine Engines.' Initial studies using the V-CAP resin system were undertaken in 1993 under a NASA Lewis contract (NAS3-26829). A first prototype unit was developed in a joint program between Textron-Lycoming (now Allied Signal) and Brunswick (now Lincoln Composites). This unit included composite end closures using low density, high temperature molded end closures. The units was similar in size and shape to a titanium case currently used on the PT-21 0 engine and was funded as part of the integrated High Performance Turbine Engine Technology (EHPTET) initiative of DOD and NASA.

  17. The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes

    NASA Astrophysics Data System (ADS)

    Sun, Wen-Ting; Liang, Tian-Ran; Wang, Hua-Bo; Li, He-Ping; Bao, Cheng-Yu

    2007-05-01

    Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform α mode discharge of the RF APGD plasmas are presented. The experiments are conducted by placing the home-made planar-type plasma generator in ambient and in a vacuum chamber, respectively, with helium as the primary plasma-forming gas. When the discharge processes occur in ambient, particularly for the lower plasma-working gas flow rates, the experimental measurements show that it is the back-diffusion effect of air in atmosphere, instead of the flow rate of the gas, that results in the obvious decrease in the breakdown voltage with increasing plasma-working gas flow rate. Further studies on the discharge characteristics, e.g. the luminous structures, the concentrations and distributions of chemically active species in plasmas, with different plasma-working gases or gas mixtures need to be conducted in future work.

  18. Supersonic compressor

    DOEpatents

    Roberts, II, William Byron; Lawlor, Shawn P.; Breidenthal, Robert E.

    2016-04-12

    A supersonic compressor including a rotor to deliver a gas at supersonic conditions to a diffuser. The diffuser includes a plurality of aerodynamic ducts that have converging and diverging portions, for deceleration of gas to subsonic conditions and then for expansion of subsonic gas, to change kinetic energy of the gas to static pressure. The aerodynamic ducts include vortex generating structures for controlling boundary layer, and structures for changing the effective contraction ratio to enable starting even when the aerodynamic ducts are designed for high pressure ratios, and structures for boundary layer control. In an embodiment, aerodynamic ducts are provided having an aspect ratio of in excess of two to one, when viewed in cross-section orthogonal to flow direction at an entrance to the aerodynamic duct.

  19. Abatement and degradation pathways of toluene in indoor air by positive corona discharge.

    PubMed

    Van Durme, J; Dewulf, J; Sysmans, W; Leys, C; Van Langenhove, H

    2007-08-01

    Indoor air concentrations of volatile organic compounds often exceed outdoor levels by a factor of 5. There is much interest in developing new technologies in order to improve indoor air quality. In this work non-thermal plasma (DC positive corona discharge) is explored as an innovative technology for indoor air purification. An inlet gas stream of 10 l min(-1) containing 0.50+/-0.02 ppm toluene was treated by the plasma reactor in atmospheric conditions. Toluene removal proved to be achievable with a characteristic energy density epsilon(0) of 50 J l(-1). Removal efficiencies were higher for 26% relative humidity (epsilon(0)=35 J l(-1)), compared with those at increased humidities (50% relative humidity, epsilon(0)=49 J l(-1)). Reaction products such as formic acid, benzaldehyde, benzyl alcohol, 3-methyl-4-nitrophenol, 4-methyl-2-nitrophenol, 4-methyl-2-propyl furan, 5-methyl-2-nitrophenol, 4-nitrophenol, 2-methyl-4,6-dinitrophenol are identified by means of mass spectrometry. Based on these by-products a toluene degradation mechanism is proposed. PMID:17490711

  20. Surface-dependent inactivation of model microorganisms with shielded sliding plasma discharges and applied air flow.

    PubMed

    Edelblute, Chelsea M; Malik, Muhammad A; Heller, Loree C

    2015-06-01

    Cold atmospheric plasma inactivates bacteria through reactive species produced from the applied gas. The use of cold plasma clinically has gained recent interest, as the need for alternative or supplementary strategies are necessary for preventing multi-drug resistant infections. The purpose of this study was to evaluate the antibacterial efficacy of a novel shielded sliding discharge based cold plasma reactor operated by nanosecond voltage pulses in atmospheric air on both biotic and inanimate surfaces. Bacterial inactivation was determined by direct quantification of colony forming units. The plasma activated air (afterglow) was bactericidal against Escherichia coli and Staphylococcus epidermidis seeded on culture media, laminate, and linoleum vinyl. In general, E. coli was more susceptible to plasma exposure. A bacterial reduction was observed with the application of air alone on a laminate surface. Whole-cell real-time PCR revealed a decrease in the presence of E. coli genomic DNA on exposed samples. These findings suggest that plasma-induced bacterial inactivation is surface-dependent. PMID:25200988

  1. The glow discharge inception and post-discharge relaxation of charged and neutral active particles in synthetic air at low pressure

    NASA Astrophysics Data System (ADS)

    Jovanović, A. P.; Marković, V. Lj; Stamenković, S. N.; Stankov, M. N.

    2015-11-01

    The study of dc glow discharge inception and post-discharge relaxation of charged and neutral active particles in synthetic air at low pressure is presented. The breakdown time delay dependence as a function of relaxation time \\overline{{{t}\\text{d}}}(τ ) (the memory curve) is measured and modelled from milliseconds to the saturation region determined by the cosmic rays and natural radioactivity level. Due to fast conversion \\text{N}2++{{\\text{O}}2}\\to {{\\text{N}}2}+\\text{O}2+ , relaxation of dc discharge in synthetic air in the time interval from one to about ninety milliseconds is dominated by the diffusion decay of molecular oxygen {{O}}_2^ + ions. The change of regimes, from ambipolar to the free diffusion limit, is investigated and the variation of effective diffusion coefficients is determined. The late relaxation is explained by the kinetics of nitrogen atoms, recombining on the surfaces of gas discharge tube and stainless steel electrodes and relevant surface recombination coefficients are determined.

  2. FAST TRACK COMMUNICATION: Asymmetric surface barrier discharge plasma driven by pulsed 13.56 MHz power in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Dedrick, J.; Boswell, R. W.; Charles, C.

    2010-09-01

    Barrier discharges are a proven method of generating plasmas at high pressures, having applications in industrial processing, materials science and aerodynamics. In this paper, we present new measurements of an asymmetric surface barrier discharge plasma driven by pulsed radio frequency (rf 13.56 MHz) power in atmospheric pressure air. The voltage, current and optical emission of the discharge are measured temporally using 2.4 kVp-p (peak to peak) 13.56 MHz rf pulses, 20 µs in duration. The results exhibit different characteristics to plasma actuators, which have similar discharge geometry but are typically driven at frequencies of up to about 10 kHz. However, the electrical measurements are similar to some other atmospheric pressure, rf capacitively coupled discharge systems with symmetric electrode configurations and different feed gases.

  3. Obtaining molecular hydrogen in electric discharge of the tornado type in air mixture with ethanol and water vapors

    NASA Astrophysics Data System (ADS)

    Levko, D. S.; Shchedrin, A. I.; Chernyak, V. Ya.; Ol'Shevskiĭ, S. V.; Nedybalyuk, O. A.

    2010-11-01

    A new plasmachemical reactor is proposed that provides a high yield of hydrogen from electric discharge in a mixture of air with ethanol and water vapors. It is shown that intense electron-molecule reactions and high temperature in the discharge region favor an increase in the degree of H2O and C2H5OH conversion into molecular hydrogen. A mechanism of the initiation of chain reactions leading to H2 formation is determined. It is established that H2 concentration reaches saturation in the region of discharge currents above 200 mA.

  4. Investigation of Lithium-Air Battery Discharge Product Formed on Carbon Nanotube and Nanofiber Electrodes

    NASA Astrophysics Data System (ADS)

    Mitchell, Robert Revell, III

    Carbon nanotubes have been actively investigated for integration in a wide variety of applications since their discovery over 20 years ago. Their myriad desirable material properties including exceptional mechanical strength, high thermal conductivities, large surface-to-volume ratios, and considerable electrical conductivities, which are attributable to a quantum mechanical ability to conduct electrons ballistically, have continued to motivate interest in this material system. While a variety of synthesis techniques exist, carbon nanotubes and nanofibers are most often conveniently synthesized using chemical vapor deposition (CVD), which involves their catalyzed growth from transition metal nanoparticles. Vertically-aligned nanotube and nanofiber carpets produced using CVD have been utilized in a variety of applications including those related to energy storage. Li-air (Li-O2) batteries have received much interest recently because of their very high theoretical energy densities (3200 Wh/kgLi2O2 ). which make them ideal candidates for energy storage devices for future fully-electric vehicles. During operation of a Li-air battery O2 is reduced on the surface a porous air cathode, reacting with Li-ions to form lithium peroxide (Li-O2). Unlike the intercalation reactions of Li-ion batteries, discharge in a Li-air cell is analogous to an electrodeposition process involving the nucleation and growth of the depositing species on a foreign substrate. Carbon nanofiber electrodes were synthesized on porous substrates using a chemical vapor deposition process and then assembled into Li-O2 cells. The large surface to volume ratio and low density of carbon nanofiber electrodes were found to yield a very high gravimetric energy density in Li-O 2 cells, approaching 75% of the theoretical energy density for Li 2O2. Further, the carbon nanofiber electrodes were found to be excellent platforms for conducting ex situ electron microscopy investigations of the deposition Li2O2 phase

  5. Strategies for NO{sub x} cleanup from air streams using dielectric barrier discharges

    SciTech Connect

    Gentile, A.C.; Kushner, M.J.

    1993-12-01

    Efficient processes for the removal of NO{sub x} from exhaust gases due to the combustion of fossil fuels is of increasing interest due to stringent EPA limits on allowable emissions. Strategies for plasma remediation of NO{sub x} using both reduction (N + NO {yields} N{sub 2} + O) and oxidation (NO{sub 2} + OH {yields} HNO{sub 3}) techniques are being developed as an energy efficient cleansing method. The dry reduction technique is preferred since there is no acidic waste product. The authors have developed a plasma chemistry computer model for atmospheric pressure gas streams excited by dielectric barrier discharges to investigate optimum methods to remove NO{sub x} from air. They will report on efficiencies for removing 100s ppm of NO{sub x} while varying water content and power deposition. Comparisons will be made to experiments by Chang et. al.

  6. A Stable, Magnetic, and Metallic Li3O4 Compound as a Discharge Product in a Li-Air Battery.

    PubMed

    Yang, Guochun; Wang, Yanchao; Ma, Yanming

    2014-08-01

    The Li-air battery with the specific energy exceeding that of a Li ion battery has been aimed as the next-generation battery. The improvement of the performance of the Li-air battery needs a full resolution of the actual discharge products. Li2O2 has been long recognized as the main discharge product, with which, however, there are obvious failures on the understanding of various experimental observations (e.g., magnetism, oxygen K-edge spectrum, etc.) on discharge products. There is a possibility of the existence of other Li-O compounds unknown thus far. Here, a hitherto unknown Li3O4 compound as a discharge product of the Li-air battery was predicted through first-principles swarm structure searching calculations. The new compound has a unique structure featuring the mixture of superoxide O2(-) and peroxide O2(2-), the first such example in the Li-O system. The existence of superoxide O2(-) creates magnetism and hole-doped metallicity. Findings of Li3O4 gave rise to direct explanations of the unresolved experimental magnetism, triple peaks of oxygen K-edge spectra, and the Raman peak at 1125 cm(-1) of the discharge products. Our work enables an opportunity for the performance of capacity, charge overpotential, and round-trip efficiency of the Li-air battery. PMID:26277938

  7. Improved Regenerative Sorbent-Compressor Refrigerator

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.

    1992-01-01

    Conceptual regenerative sorbent-compressor refrigerator attains regeneration efficiency and, therefore, overall power efficiency and performance greater than conventional refrigerators. Includes two fluid loops. In one, CH2FCF3 (R134a) ciculates by physical adsorption and desorption in four activated-charcoal sorption compressors. In other, liquid or gas coolant circulated by pump. Wave of regenerative heating and cooling propagates cyclically like peristatic wave among sorption compressors and associated heat exchangers. Powered by electricity, oil, gas, solar heat, or waste heat. Used as air conditioners, refrigerators, and heat pumps in industrial, home, and automotive applications.

  8. Simulation study on nitrogen vibrational kinetics in a single nanosecond pulse high voltage air discharge

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Zhou, Qianhong; Dong, Zhiwei

    2016-05-01

    We report a simulation study on nitrogen vibrational kinetics N 2 ( X 1 Σg + , v = 0 - 12 ) in a single nanosecond pulse high voltage discharge in dry-air at a pressure of 100 Torr. Apart from the usual processes such as vibrational-vibrational exchange and vibrational-translational relaxation, the state-specific vibrational kinetics take into account the electronic-vibrational (E-V) process and chemical-vibrational process. The vibrational kinetics, coupled with electron Boltzmann equation solver, plasma chemical kinetics, and gas thermal balance are used to model the 100 ns discharge and its subsequent 10 ms afterglow. The self-consistent model shows good agreement with recent experimental results, with regard to time-resolved vibrational and translational temperature. According to the modeling results, The E-V mechanism has a small but non-negligible effect (about 2%) in rising of vibrational quanta in the early afterglow from 100 ns to 1μs. Another possible reason is the convective transport associated with the gas dynamic expansion in time delays around 1μs to 10 μs.

  9. High altitude atmospheric discharges according to the runaway air breakdown mechanism

    SciTech Connect

    Symbalisty, E.; Roussel-Dupre, R.; Yukhimuk, V.; Taranenko, Y.

    1997-04-01

    High altitude optical transients - red sprites, blue jets, and elves - are modeled in the context of the relativistic electron runaway air breakdown mechanism. These emissions are usually associated with large mesoscale convective systems (hereafter MCS). In thunderstorms cloud electrification proceeds over a time scale long enough to permit the conducting atmosphere above the cloud to polarize and short out the thunderstorm electric field. When a lightning strike rapidly neutralizes a cloud charge layer runaway driving fields can develop in the stratosphere and mesosphere. According to present simulations of the full runaway process the variety of observed optical emissions are due to the nature of the normal lightning event in the MCS that kick starts the runaway avalanche. In this paper the authors describe some details of the model, present the results of the evolution of the primary electron population, and summarize the initial conditions necessary for different types of discharges. Two companion papers present (a) the predicted optical, gamma ray, and radio emissions caused by these electrical discharges, and (b) the time evolution of the secondary electron population and its implications in terms of observables.

  10. Spectral Evidence for Ionization in Air-Filled Glow Discharge Tubes: Application to Sprites

    NASA Astrophysics Data System (ADS)

    Armstrong, R. A.; Williams, E. R.; Golka, R. K.; Williams, D. R.

    2001-12-01

    The question of ionization in sprites and the evidence for VLF backscatter from sprites has motivated a quantitative spectral analysis of the various (classical) regions of the glow discharge tube under DC excitation and at air densities appropriate for sprites in the mesosphere. A PR-650 colorimeter (Photo Research, Inc.) has enabled calibrated irradiance measurements for localized zones along the axis of the discharge tube--in the dominantly blue negative glow, in the Faraday dark space and in the red/pink positive column. Consistent with historical nomenclature, nitrogen first and second positive emission is dominant in the positive column (associated with neutral N2), and nitrogen first negative emission, with a prominent peak at 4278 A, is dominant in the blue negative glow (associated with ionized N2+). Whereas nitrogen first and second positive emission are also detected in the negative glow, no spectral evidence for ionization (no 4279, no 3914, no Meinel) is found in the red/pink positive column. This negative result is attributed not to an absence of ionization in the positive column, but rather to a sparse population of N2+ relative to neutral nitrogen in this region, and to the prominent emission in the blue part of the spectrum due to nitrogen second positive. A similar interpretation may be appropriate for the time-integrated spectra from the red body of sprites, also lacking direct evidence for ionization.

  11. Refrigeration system having dual suction port compressor

    DOEpatents

    Wu, Guolian

    2016-01-05

    A cooling system for appliances, air conditioners, and other spaces includes a compressor, and a condenser that receives refrigerant from the compressor. The system also includes an evaporator that receives refrigerant from the condenser. Refrigerant received from the condenser flows through an upstream portion of the evaporator. A first portion of the refrigerant flows to the compressor without passing through a downstream portion of the evaporator, and a second portion of the refrigerant from the upstream portion of the condenser flows through the downstream portion of the evaporator after passing through the upstream portion of the evaporator. The second portion of the refrigerant flows to the compressor after passing through the downstream portion of the evaporator. The refrigeration system may be configured to cool an appliance such as a refrigerator and/or freezer, or it may be utilized in air conditioners for buildings, motor vehicles, or other such spaces.

  12. The physics of pulsed streamer discharge in high pressure air and applications to engine techonologies

    NASA Astrophysics Data System (ADS)

    Lin, Yung-Hsu

    The goal of this dissertation is to study high pressure streamers in air and apply it to diesel engine technologies. Nanosecond scale pulsed high voltage discharges in air/fuel mixtures can generate radicals which in turn have been shown to improve combustion efficiency in gasoline fueled internal combustion engines. We are exploring the possibility to extend such transient plasma generation and expected radical species generation to the range of pressures encountered in compression-ignition (diesel) engines having compression ratios of ˜20:1, thereby improving lean burning efficiency and extending the range of lean combustion. At the beginning of this dissertation, research into streamer discharges is reviewed. Then, we conducted experiments of streamer propagation at high pressures, calculated the streamer velocity based on both optical and electrical measurements, and the similarity law was checked by analyzing the streamer velocity as a function of the reduced electric field, E/P. Our results showed that the similarity law is invalid, and an empirical scaling factor, E/√P, is obtained and verified by dimensional analysis. The equation derived from the dimensional analysis will be beneficial to proper electrode and pulse generator design for transient plasma assisted internal engine experiments. Along with the high pressure study, we applied such technique on diesel engine to improve the fuel efficiency and exhaust treatment. We observed a small effect of transient plasma on peak pressure, which implied that transient plasma has the capability to improve the fuel consumption. In addition, the NO can be reduced effectively by the same technique and the energy cost is 30 eV per NO molecule.

  13. Stage-by-Stage and Parallel Flow Path Compressor Modeling for a Variable Cycle Engine, NASA Advanced Air Vehicles Program - Commercial Supersonic Technology Project - AeroServoElasticity

    NASA Technical Reports Server (NTRS)

    Kopasakis, George; Connolly, Joseph W.; Cheng, Larry

    2015-01-01

    This paper covers the development of stage-by-stage and parallel flow path compressor modeling approaches for a Variable Cycle Engine. The stage-by-stage compressor modeling approach is an extension of a technique for lumped volume dynamics and performance characteristic modeling. It was developed to improve the accuracy of axial compressor dynamics over lumped volume dynamics modeling. The stage-by-stage compressor model presented here is formulated into a parallel flow path model that includes both axial and rotational dynamics. This is done to enable the study of compressor and propulsion system dynamic performance under flow distortion conditions. The approaches utilized here are generic and should be applicable for the modeling of any axial flow compressor design accurate time domain simulations. The objective of this work is as follows. Given the parameters describing the conditions of atmospheric disturbances, and utilizing the derived formulations, directly compute the transfer function poles and zeros describing these disturbances for acoustic velocity, temperature, pressure, and density. Time domain simulations of representative atmospheric turbulence can then be developed by utilizing these computed transfer functions together with the disturbance frequencies of interest.

  14. 5. INTERIOR, LOOKING PAST HELIUM COMPRESSORS NO. 3 AND NO. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. INTERIOR, LOOKING PAST HELIUM COMPRESSORS NO. 3 AND NO. 2, TO NORTHEAST FRONT. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Helium Compression Plant, Test Area 1-115, intersection of Altair & Saturn Boulevards, Boron, Kern County, CA

  15. 8. ORIGINAL HELIUM COMPRESSOR, CIRCA 1957, BY HASKELL ENGINEERING, GLENDALE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. ORIGINAL HELIUM COMPRESSOR, CIRCA 1957, BY HASKELL ENGINEERING, GLENDALE, CALIFORNIA. Looking north. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Helium Compression Plant, Test Area 1-115, intersection of Altair & Saturn Boulevards, Boron, Kern County, CA

  16. Time-lag properties of corona streamer discharges between impulse sphere and dc needle electrodes under atmospheric air conditions

    NASA Astrophysics Data System (ADS)

    Okano, Daisuke

    2013-02-01

    In this study of corona streamer discharges from an impulse generator using a dc power supply, the relationship of the discharge time-lag with the dc bias voltage between the sphere-to-needle electrodes under atmospheric conditions is investigated. Devices utilizing corona discharges have been used to purify air or water, destroy bacteria, and to remove undesirable substances, and in order to achieve fast response times and high power efficiencies in such devices, it is important to minimize the time-lag of the corona discharge. Our experimental results show that (a) the discharge path of a negatively biased needle electrode will be straighter than that of a positively biased needle and (b) the discharge threshold voltage in both the positive and the negative needle electrodes is nearly equal to 33 kV. By expressing the discharge voltage as a power function of time-lag, the extent of corona generation can be quantitatively specified using the exponent of this power function. The observed behavior of a corona streamer discharge between the negative spherical and the positive needle electrodes indicates that the largest power exponent is associated with the shortest time-lag, owing to the reduction in the statistical time-lag in the absence of a formative time-lag.

  17. Time-lag properties of corona streamer discharges between impulse sphere and dc needle electrodes under atmospheric air conditions.

    PubMed

    Okano, Daisuke

    2013-02-01

    In this study of corona streamer discharges from an impulse generator using a dc power supply, the relationship of the discharge time-lag with the dc bias voltage between the sphere-to-needle electrodes under atmospheric conditions is investigated. Devices utilizing corona discharges have been used to purify air or water, destroy bacteria, and to remove undesirable substances, and in order to achieve fast response times and high power efficiencies in such devices, it is important to minimize the time-lag of the corona discharge. Our experimental results show that (a) the discharge path of a negatively biased needle electrode will be straighter than that of a positively biased needle and (b) the discharge threshold voltage in both the positive and the negative needle electrodes is nearly equal to 33 kV. By expressing the discharge voltage as a power function of time-lag, the extent of corona generation can be quantitatively specified using the exponent of this power function. The observed behavior of a corona streamer discharge between the negative spherical and the positive needle electrodes indicates that the largest power exponent is associated with the shortest time-lag, owing to the reduction in the statistical time-lag in the absence of a formative time-lag. PMID:23464233

  18. Electro-hydrodynamics and kinetic modelling of polluted air flow activated by multi-tip-to-plane corona discharge

    SciTech Connect

    Meziane, M.; Eichwald, O.; Ducasse, O.; Marchal, F.; Sarrette, J. P.; Yousfi, M.

    2013-04-21

    The present paper is devoted to the 2D simulation of an Atmospheric Corona Discharge Reactor (ACDR) involving 10 pins powered by a DC high voltage and positioned 7 mm above a grounded metallic plane. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The simulation involves the electro-dynamic, chemical kinetic, and neutral gas hydrodynamic phenomena that influence the kinetics of the chemical species transformation. Each discharge stage (including the primary and the secondary streamers development and the resulting thermal shock) lasts about one hundred nanoseconds while the post-discharge stages occurring between two successive discharge phases last one hundred microseconds. The ACDR is crossed by a lateral air flow including 400 ppm of NO. During the considered time scale of 10 ms, one hundred discharge/post-discharge cycles are simulated. The simulation involves the radical formation and thermal exchange between the discharges and the background gas. The results show how the successive discharges activate the flow gas and how the induced turbulence phenomena affect the redistribution of the thermal energy and the chemical kinetics inside the ACDR.

  19. Centrifugal reciprocating compressor

    NASA Technical Reports Server (NTRS)

    High, W. H.

    1980-01-01

    Efficient compressor uses centrifugal force to compress gas. System incorporates two coupled dc motors, each driving separate centrifugal reciprocating-compressor assembly. Motors are synchronized to accelerate and decelerate alternately.

  20. On the physical processes ruling an atmospheric pressure air glow discharge operating in an intermediate current regime

    SciTech Connect

    Prevosto, L. Mancinelli, B.; Chamorro, J. C.; Cejas, E.; Kelly, H.

    2015-02-15

    Low-frequency (100 Hz), intermediate-current (50 to 200 mA) glow discharges were experimentally investigated in atmospheric pressure air between blunt copper electrodes. Voltage–current characteristics and images of the discharge for different inter-electrode distances are reported. A cathode-fall voltage close to 360 V and a current density at the cathode surface of about 11 A/cm{sup 2}, both independent of the discharge current, were found. The visible emissive structure of the discharge resembles to that of a typical low-pressure glow, thus suggesting a glow-like electric field distribution in the discharge. A kinetic model for the discharge ionization processes is also presented with the aim of identifying the main physical processes ruling the discharge behavior. The numerical results indicate the presence of a non-equilibrium plasma with rather high gas temperature (above 4000 K) leading to the production of components such as NO, O, and N which are usually absent in low-current glows. Hence, the ionization by electron-impact is replaced by associative ionization, which is independent of the reduced electric field. This leads to a negative current-voltage characteristic curve, in spite of the glow-like features of the discharge. On the other hand, several estimations show that the discharge seems to be stabilized by heat conduction; being thermally stable due to its reduced size. All the quoted results indicate that although this discharge regime might be considered to be close to an arc, it is still a glow discharge as demonstrated by its overall properties, supported also by the presence of thermal non-equilibrium.

  1. Surface treatment of aramid fiber by air dielectric barrier discharge plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Jia, Caixia; Chen, Ping; Liu, Wei; Li, Bin; Wang, Qian

    2011-02-01

    Aramid fiber samples are treated by air dielectric barrier discharge (DBD) plasma at atmospheric pressure; the plasma treatment time is investigated as the major parameter. The effects of this treatment on the fiber surface physical and chemical properties are studied by using surface characterization techniques. Scanning electron microscopy (SEM) is performed to determine the surface morphology changes, X-ray photoelectron spectroscopy (XPS) is analyzed to reveal the surface chemical composition variations and dynamic contact angle analysis (DCAA) is used to examine the changes of the fiber surface wettability. In addition, the wetting behavior of a kind of thermoplastic resin, poly(phthalazinone ether sulfone ketone) (PPESK), on aramid fiber surface is also observed by SEM photos. The study shows that there seems to be an optimum treatment condition for surface modification of aramid fiber by the air DBD plasma. In this paper, after the 12 s, 27.6 W/cm3 plasma treatment the aramid fiber surface roughness is significantly improved, some new oxygen-containing groups such as C-O, Cdbnd O and Odbnd C-O are generated on the fiber surface and the fiber surface wettability is greatly enhanced, which results in the better wetting behavior of PPESK resin on the plasma-treated aramid fiber.

  2. Improved Ethanol Production from Xylose by Candida shehatae Induced by Dielectric Barrier Discharge Air Plasma

    NASA Astrophysics Data System (ADS)

    Chen, Huixia; Xiu, Zhilong; Bai, Fengwu

    2014-06-01

    Xylose fermentation is essential for ethanol production from lignocellulosic biomass. Exposure of the xylose-fermenting yeast Candida shehatae (C. shehatae) CICC1766 to atmospheric pressure dielectric barrier discharge (DBD) air plasma yields a clone (designated as C81015) with stability, which exhibits a higher ethanol fermentation rate from xylose, giving a maximal enhancement in ethanol production of 36.2% compared to the control (untreated). However, the biomass production of C81015 is lower than that of the control. Analysis of the NADH (nicotinamide adenine dinucleotide)- and NADPH (nicotinamide adenine dinucleotide phosphate)-linked xylose reductases and NAD+-linked xylitol dehydrogenase indicates that their activities are enhanced by 34.1%, 61.5% and 66.3%, respectively, suggesting that the activities of these three enzymes are responsible for improving ethanol fermentation in C81015 with xylose as a substrate. The results of this study show that DBD air plasma could serve as a novel and effective means of generating microbial strains that can better use xylose for ethanol fermentation.

  3. Wind tunnel experiments on flow separation control of an Unmanned Air Vehicle by nanosecond discharge plasma aerodynamic actuation

    NASA Astrophysics Data System (ADS)

    Kang, Chen; Hua, Liang

    2016-02-01

    Plasma flow control (PFC) is a new kind of active flow control technology, which can improve the aerodynamic performances of aircrafts remarkably. The flow separation control of an unmanned air vehicle (UAV) by nanosecond discharge plasma aerodynamic actuation (NDPAA) is investigated experimentally in this paper. Experimental results show that the applied voltages for both the nanosecond discharge and the millisecond discharge are nearly the same, but the current for nanosecond discharge (30 A) is much bigger than that for millisecond discharge (0.1 A). The flow field induced by the NDPAA is similar to a shock wave upward, and has a maximal velocity of less than 0.5 m/s. Fast heating effect for nanosecond discharge induces shock waves in the quiescent air. The lasting time of the shock waves is about 80 μs and its spread velocity is nearly 380 m/s. By using the NDPAA, the flow separation on the suction side of the UAV can be totally suppressed and the critical stall angle of attack increases from 20° to 27° with a maximal lift coefficient increment of 11.24%. The flow separation can be suppressed when the discharge voltage is larger than the threshold value, and the optimum operation frequency for the NDPAA is the one which makes the Strouhal number equal one. The NDPAA is more effective than the millisecond discharge plasma aerodynamic actuation (MDPAA) in boundary layer flow control. The main mechanism for nanosecond discharge is shock effect. Shock effect is more effective in flow control than momentum effect in high speed flow control. Project supported by the National Natural Science Foundation of China (Grant Nos. 61503302, 51207169, and 51276197), the China Postdoctoral Science Foundation (Grant No. 2014M562446), and the Natural Science Foundation of Shaanxi Province, China (Grant No. 2015JM1001).

  4. Performance of Compressor of XJ-41-V Turbojet Engine. 4; Performance Analysis Over Range of Compressor Speeds from 5000 to 10,000 RPM

    NASA Technical Reports Server (NTRS)

    Creagh, John W. R.; Ginsburg, Ambrose

    1948-01-01

    An investigation of the XJ-41-V turbojet-engine compressor was conducted to determine the performance of the compressor and to obtain fundamental information on the aerodynamic problems associated with large centrifugal-type compressors. The results of the research conducted on the original compressor indicated the compressor would not meet the desired engine-design air-flow requirements because of an air-flow restriction in the vaned collector. The compressor air-flow choking point occurred near the entrance to the vaned-collector passage and was instigated by a poor mass-flow distribution at the vane entrance and from relatively large negative angles of attack of the air stream along the entrance edges of the vanes at the outer passage wall and large positive angles of attack at the inner passage wall. As a result of the analysis, a design change of the vaned collector entrance is recommended for improving the maximum flow capacity of the compressor.

  5. Producing nitric oxide by pulsed electrical discharge in air for portable inhalation therapy.

    PubMed

    Yu, Binglan; Muenster, Stefan; Blaesi, Aron H; Bloch, Donald B; Zapol, Warren M

    2015-07-01

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation and is an effective therapy for treating pulmonary hypertension in adults and children. In the United States, the average cost of 5 days of inhaled NO for persistent pulmonary hypertension of the newborn is about $14,000. NO therapy involves gas cylinders and distribution, a complex delivery device, gas monitoring and calibration equipment, and a trained respiratory therapy staff. The objective of this study was to develop a lightweight, portable device to serve as a simple and economical method of producing pure NO from air for bedside or portable use. Two NO generators were designed and tested: an offline NO generator and an inline NO generator placed directly within the inspiratory line. Both generators use pulsed electrical discharges to produce therapeutic range NO (5 to 80 parts per million) at gas flow rates of 0.5 to 5 liters/min. NO was produced from air, as well as gas mixtures containing up to 90% O2 and 10% N2. Potentially toxic gases produced in the plasma, including nitrogen dioxide (NO2) and ozone (O3), were removed using a calcium hydroxide scavenger. An iridium spark electrode produced the lowest ratio of NO2/NO. In lambs with acute pulmonary hypertension, breathing electrically generated NO produced pulmonary vasodilation and reduced pulmonary arterial pressure and pulmonary vascular resistance index. In conclusion, electrical plasma NO generation produces therapeutic levels of NO from air. After scavenging to remove NO2 and O3 and filtration to remove particles, electrically produced NO can provide safe and effective treatment of pulmonary hypertension. PMID:26136478

  6. Vibrational and rotational CARS measurements of nitrogen in afterglow of streamer discharge in atmospheric pressure fuel/air mixtures

    NASA Astrophysics Data System (ADS)

    Pendleton, S. J.; Montello, A.; Carter, C.; Lempert, W.; Gundersen, M. A.

    2012-12-01

    The use of nonequilibrium plasma generated by nanosecond discharges to ignite fuel/air mixtures, known as transient plasma ignition (TPI), has been shown to effectively reduce ignition delay and improve engine performance relative to spark ignition for combustion engines. While this method is potentially useful for many engine applications, at present the underlying physics are poorly understood. This work uses coherent anti-Stokes Raman spectroscopy (CARS) to measure the rotational and vibrational excitation of nitrogen molecules in the discharge afterglow in a variety of fuel/air mixtures outside the limits of combustion in order to elucidate the thermal behaviour of TPI. The time evolution of relative populations of vibrationally excited states of nitrogen in the electronic ground state are reported for each gas mixture; it is shown that generation of these vibrationally excited states is inefficient during the discharge in air but that generation occurs at a high rate roughly 5 µs following the discharge; with the addition of fuels vibrationally excited states are observed during the discharge but an increase in population is still seen at 5 µs. Possible mechanisms for this behaviour are discussed. In addition, rotational temperature increases of at least 500 K are reported for all gas mixtures. The effect of this temperature increase on ignition, reaction rates, and thermal energy pathways are discussed.

  7. Miniature Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    Sixsmith, Herbert

    1989-01-01

    Miniature turbocompressor designed for reliability and long life. Cryogenic system includes compressor, turboexpander, and heat exchanger provides 5 W of refrigeration at 70 K from 150 W input power. Design speed of machine 510,000 rpm. Compressor has gas-lubricated journal bearings and magnetic thrust bearing. When compressor runs no bearing contact and no wear.

  8. Characteristics of TiO2 Thin Film Surfaces Treated by Helium and Air Dielectric Barrier Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Kawakami, Retsuo; Niibe, Masahito; Takeichi, Atsushi; Mori, Yuta; Konishi, Masashi; Kotaka, Takuya; Matsunaga, Fumihiko; Takasaki, Toshihide; Kitano, Takanori; Miyazaki, Takahiro; Inaoka, Takeshi; Tominaga, Kikuo

    2012-08-01

    The characteristics of TiO2 thin film surfaces treated with He and air dielectric barrier discharge (DBD) plasmas at different gas pressures are investigated. There is a difference between the two DBD plasma characteristics: for He-DBD, which is an atmospheric pressure glow discharge (APGD), the breakdown voltage and discharge current hardly change with increasing gas pressure, whereas for air-DBD, which is basically a filamentary discharge, they increase with increasing gas pressure. There is also a difference between the characteristics of TiO2 surfaces treated with the two DBDs. The surface roughness for He-DBD is lower than the roughness of the as-grown surface, whereas that for air-DBD is higher. The surface hydrophilicity for He-DBD is more enhanced than the hydrophilicity of the as-grown surface regardless of UV irradiation. The hydrophilicity for air-DBD is dependent on UV irradiation. It is more enhanced with UV irradiation; it is not improved adequately without UV irradiation.

  9. Permanent hydrophilization of outer and inner surfaces of polytetrafluoroethylene tubes using ambient air plasma generated by surface dielectric barrier discharges

    SciTech Connect

    Pavliňák, D.; Galmiz, O.; Zemánek, M.; Brablec, A.; Čech, J.; Černák, M.

    2014-10-13

    We present an atmospheric pressure ambient air plasma technique developed for technically simple treatment of inner and/or outer surfaces of plastic tubes and other hollow dielectric bodies. It is based on surface dielectric barrier discharge generating visually diffuse plasma layers along the treated dielectric surfaces using water-solution electrodes. The observed visual uniformity and measured plasma rotational and vibrational temperatures of 333 K and 2350 K indicate that the discharge can be readily applied to material surface treatment without significant thermal effect. This is exemplified by the obtained permanent surface hydrophilization of polytetrafluoroethylene tubes related to the replacement of a high fraction (more than 80%) of the surface fluorine determined by X-ray photoelectron spectroscopy. A tentative explanation of the discharge mechanism based on high-speed camera observations and the discharge current and voltage of measurements is outlined.

  10. Thermal and hydrodynamic effects of nanosecond discharges in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Xu, D. A.; Shneider, M. N.; Lacoste, D. A.; Laux, C. O.

    2014-06-01

    We present quantitative schlieren measurements and numerical analyses of the thermal and hydrodynamic effects of a nanosecond repetitively pulsed (NRP) discharge in atmospheric pressure air at 300 and 1000 K. The plasma is created by voltage pulses at an amplitude of 10 kV and a duration of 10 ns, applied at a frequency of 1-10 kHz between two pin electrodes separated by 2 or 4 mm. The electrical energy of each pulse is of the order of 1 mJ. We recorded single-shot schlieren images starting from 50 ns to 3 µs after the discharge. The time-resolved images show the shock-wave propagation and the expansion of the heated gas channel. Gas density profiles simulated in 1D cylindrical coordinates have been used to reconstruct numerical schlieren images for comparison with experimental ones. We propose an original method to determine the initial gas temperature and the fraction of energy transferred into ultrafast gas heating, using a comparison of the contrast profiles obtained from experimental and numerical schlieren images. This method is found to be much more sensitive to these parameters than the direct comparison of measured and predicted shock-wave and heated channel radii. The results show that a significant fraction of the electric energy is converted into gas heating within a few tens of ns. The values range from about 25% at a reduced electric field of 164 Td to about 75% at 270 Td, with a strong dependance on the initial gas temperature. These experiments support the fast heating processes via dissociative quenching of N2(B3 Πg, C3 Πu) by molecular oxygen.

  11. Computation of Flow in Screw Compressors

    NASA Astrophysics Data System (ADS)

    Kalitzin, Georgi; Cai, Xiaodan; Reba, Ramons; Medic, Gorazd

    2015-08-01

    A CFD model enabling accurate and computationally affordable simulation of unsteady flow in screw compressors has been developed. This paper focuses on computational aspects, including real-gas CFD using hybrid structured/unstructured moving grids, and specifics of grid generation for moving rotors and their communication with the discharge plenum.

  12. 40 CFR 63.1012 - Compressor standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 11 2013-07-01 2013-07-01 false Compressor standards. 63.1012 Section 63.1012 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES (CONTINUED) National Emission Standards for Equipment...

  13. Study on electrical characteristics of barrier-free atmospheric air diffuse discharge generated by nanosecond pulses and long wire electrodes

    SciTech Connect

    Li, Lee Liu, Yun-Long; Teng, Yun; Liu, Lun; Pan, Yuan

    2014-07-15

    In room-temperature atmospheric air, the large-scale diffuse plasmas can be generated via high-voltage nanosecond pulses with short rise-time and wire electrodes. Diffuse discharge with the wire electrode length up to 110.0 cm and the discharge spacing of several centimeters has been investigated in this paper. Electrical characteristics of diffuse discharge have been analyzed by their optical photographs and measuring of the voltage and current waveforms. Experimental results show the electrode spacing, and the length of wire electrodes can influence the intensity and mode transition of diffuse discharge. The characteristic of current waveforms is that there are several current oscillation peaks at the time of applied pulsed voltage peak, and at the tail of applied pulse, the conduction current component will compensate the displacement one so that the measured current is unidirectional in diffuse discharge mode. The transition from diffuse discharge to arc discharge is always with the increasing of conduction current density. As for nanosecond pulses with long tail, the long wire electrodes are help for generating non-equilibrium diffuse plasmas.

  14. Numerical studies of nitric oxide formation in nanosecond-pulsed discharge-stabilized flames of premixed methane/air.

    PubMed

    Bak, Moon Soo; Cappelli, Mark A

    2015-08-13

    A simulation is developed to investigate the kinetics of nitric oxide (NO) formation in premixed methane/air combustion stabilized by nanosecond-pulsed discharges. The simulation consists of two connected parts. The first part calculates the kinetics within the discharge while considering both plasma/combustion reactions and species diffusion, advection and thermal conduction to the surrounding flow. The second part calculates the kinetics of the overall flow after mixing the discharge flow with the surrounding flow to account for the effect that the discharge has on the overall kinetics. The simulation reveals that the discharge produces a significant amount of atomic oxygen (O) as a result of the high discharge temperature and dissociative quenching of excited state nitrogen by molecular oxygen. This atomic oxygen subsequently produces hydroxyl (OH) radicals. The fractions of these O and OH then undergo Zel'dovich reactions and are found to contribute to as much as 73% of the total NO that is produced. The post-discharge simulation shows that the NO survives within the flow once produced. PMID:26170428

  15. FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

    NASA Astrophysics Data System (ADS)

    Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

    2010-01-01

    Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

  16. Development of an empirical model of a variable speed vapor injection compressor used in a Modelica-based dynamic model of a residential air source heat pump

    NASA Astrophysics Data System (ADS)

    Dechesne, Bertrand; Bertagnolio, Stephane; Lemort, Vincent

    2015-08-01

    This paper presents a steady-state model of a variable speed vapour injection scroll compressor. Two compressors were investigated. The developed empirical model is based on five dimensionless polynomials that were fitted using experimental data from a 2.7kW scroll compressor. A second set of data was used to show the prediction of the presented model for an other device which exhibits a different swept volume. In both cases, the suction and injection mass flow rate were respectively predicted with a coefficient of determination equal to 99.9 and 94.3% and for the consumed power, 98.4% and 95.6%. A Modelica based dynamic model is then presented. The steady-state validation of the main components models is performed. Finally the control of the cycle using two PID controllers is presented and commented.

  17. Silent Discharge Plasma Technology for the Treatment of Air Toxics and Other Applications

    SciTech Connect

    Rosocha, Louis A.; Chase, Peter J.; Gross, Michael P.

    1998-09-21

    Under this CRADA, the Los Alamos National Laboratory (LANL) and High Mesa Technologies, Inc. (HMT) carried out a joint project on the development of the silent discharge plasma (SDP) technology for the treatment of hazardous air pollutants and other hazardous or toxic chemicals. The project had two major components: a technology-demonstration part and a scale-up and commercialization part. In the first part, a small-scale, mobile SDP plasma processor, which was being developed under a CRADA with the Electric Power Research Institute (EPRI) was the mobile equipment was modified for higher capacity service and employed for an innovative remediation technologies demonstration on soil-vapor extraction off-gases at the McClellan Air Force Base near Sacramento, CA. The performance of the SDP system for the variety of volatile organic compounds (VOCs) encountered at the McClellan site was sufficiently promising to the project HMT and LANL worked together to formulate a scale-up strategy and commercialization/manufacturing plan, and to design a prototype scaled-up SDP unit. HMT and LANL are now in the final stages of completing a licensing agreement for the technology and HMT is in the process of raising funds to engineer and manufacture commercial prototype SDP equipment focused on stack-gas emissions control and environmental remediation. HMT, in collaboration with another Northern New Mexico business, Coyote Aerospace, has also been successful in receiving a Phase I Small Business Innovative Research (SBIR) award from the Army Research Office to develop, design, and construct a small non-thermal plasma reactor for laboratory studies ("Non-Thermal Plasma Reactor for Control of Fugitive Emissions of Toxic Gases")

  18. Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air

    NASA Astrophysics Data System (ADS)

    Wei, Linsheng; Peng, Bangfa; Li, Ming; Zhang, Yafang; Hu, Zhaoji

    2016-02-01

    A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 104 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O2+, O3- and O2(1Δg) in pulsed DBD in air, respectively. N2O has the largest density among nitrogen oxides. e and N2+ densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O2+, O, O3, N2(A3Σ) and N2O densities reach maximum values in the vicinity of the anode. supported by National Natural Science Foundation of China (Nos. 51366012 and 11105067), Jiangxi Province Young Scientists (Jinggang Star) Cultivation Plan of China (No. 20133BCB23008), Natural Science Foundation of Jiangxi, China (No. 20151BAB206047) and Jiangxi Province Higher School Science and Technology Landing Plan of China (No. KJLD-14015)

  19. Antimicrobial Efficacy of Two Surface Barrier Discharges with Air Plasma against In Vitro Biofilms

    PubMed Central

    Matthes, Rutger; Bender, Claudia; Schlüter, Rabea; Koban, Ina; Bussiahn, René; Reuter, Stephan; Lademann, Jürgen; Weltmann, Klaus-Dieter; Kramer, Axel

    2013-01-01

    The treatment of infected wounds is one possible therapeutic aspect of plasma medicine. Chronic wounds are often associated with microbial biofilms which limit the efficacy of antiseptics. The present study investigates two different surface barrier discharges with air plasma to compare their efficacy against microbial biofilms with chlorhexidine digluconate solution (CHX) as representative of an important antibiofilm antiseptic. Pseudomonas aeruginosa SG81 and Staphylococcus epidermidis RP62A were cultivated on polycarbonate discs. The biofilms were treated for 30, 60, 150, 300 or 600 s with plasma or for 600 s with 0.1% CHX, respectively. After treatment, biofilms were dispensed by ultrasound and the antimicrobial effects were determined as difference in the number of the colony forming units by microbial culture. A high antimicrobial efficacy on biofilms of both plasma sources in comparison to CHX treatment was shown. The efficacy differs between the used strains and plasma sources. For illustration, the biofilms were examined under a scanning electron microscope before and after treatment. Additionally, cytotoxicity was determined by the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay with L929 mouse fibroblast cell line. The cell toxicity of the used plasma limits its applicability on human tissue to maximally 150 s. The emitted UV irradiance was measured to estimate whether UV could limit the application on human tissue at the given parameters. It was found that the UV emission is negligibly low. In conclusion, the results support the assumption that air plasma could be an option for therapy of chronic wounds. PMID:23894661

  20. 2D simulation of active species and ozone production in a multi-tip DC air corona discharge

    NASA Astrophysics Data System (ADS)

    Meziane, M.; Eichwald, O.; Sarrette, J. P.; Ducasse, O.; Yousfi, M.

    2011-11-01

    The present paper shows for the first time in the literature a complete 2D simulation of the ozone production in a DC positive multi-tip to plane corona discharge reactor crossed by a dry air flow at atmospheric pressure. The simulation is undertaken until 1 ms and involves tens of successive discharge and post-discharge phases. The air flow is stressed by several monofilament corona discharges generated by a maximum of four anodic tips distributed along the reactor. The nonstationary hydrodynamics model for reactive gas mixture is solved using the commercial FLUENT software. During each discharge phase, thermal and vibrational energies as well as densities of radical and metastable excited species are locally injected as source terms in the gas medium surrounding each tip. The chosen chemical model involves 10 neutral species reacting following 24 reactions. The obtained results allow us to follow the cartography of the temperature and the ozone production inside the corona reactor as a function of the number of high voltage anodic tips.

  1. Atomic oxygen dynamics in an air dielectric barrier discharge: a combined diagnostic and modeling approach

    NASA Astrophysics Data System (ADS)

    Baldus, Sabrina; Schröder, Daniel; Bibinov, Nikita; Schulz-von der Gathen, Volker; Awakowicz, Peter

    2015-06-01

    Cold atmospheric pressure plasmas are a promising alternative therapy for treatment of chronic wounds, as they have already shown in clinical trials. In this study an air dielectric barrier discharge (DBD) developed for therapeutic use in dermatology is characterized with respect to the plasma produced reactive oxygen species, namely atomic oxygen and ozone, which are known to be of great importance to wound healing. To understand the plasma chemistry of the applied DBD, xenon-calibrated two-photon laser-induced fluorescence spectroscopy and optical absorption spectroscopy are applied. The measured spatial distributions are shown and compared to each other. A model of the afterglow chemistry based on optical emission spectroscopy is developed to cross-check the measurement results and obtain insight into the dynamics of the considered reactive oxygen species. The atomic oxygen density is found to be located mostly between the electrodes with a maximum density of {{n}\\text{O}}=6× {{10}16} cm-3 . Time resolved measurements reveal a constant atomic oxygen density between two high voltage pulses. The ozone is measured up to 3 mm outside the active plasma volume, reaching a maximum value of {{n}{{\\text{O}3}}}=3× {{10}16} cm-3 between the electrodes.

  2. Quantitative Determination of the Breakdown Field of Air from Van de Graaff Generator Discharge

    NASA Astrophysics Data System (ADS)

    Beach, John; Chartrand, Bridget; Gallagher, Hugh

    2016-03-01

    The Van de Graaff generator (VG) is ubiquitous in electrostatic demonstrations because of the large static charge and dramatic sparks produced. We have developed a novel technique for determining the breakdown field of air using the VG. When a spark occurs, the force of attraction between the VG and a discharge sphere suspended above it is measured by a Pasco force sensor. At this time the charge is not symmetric but pulled towards the near side of the spheres by mutual attraction. In order to interpret the measured force in terms of the breakdown field, an accurate model of the charge distribution is needed. Using the method of images for a spherical conductor in an iterative fashion we can provide this model. The electric field in the vicinity of the spheres is then calculated from the charge distribution and its maximum value is the breakdown field. In preliminary work, we determined the breakdown field to be 3.1x106 N/C at 24.9 C and 18% relative humidity. We will report our most recent determination of the breakdown field using this method and discuss the validity of the results in terms of accepted values, experimental limitations and sensitivity to the charge distribution model.

  3. ADI-FDTD modeling of microwave plasma discharges in air towards fully three-dimensional simulations

    NASA Astrophysics Data System (ADS)

    Kourtzanidis, Konstantinos; Rogier, François; Boeuf, Jean-Pierre

    2015-10-01

    Plasma formation and propagation during microwave breakdown has been extensively studied during the last decades. Numerical modeling of the strong coupling between the high frequency electromagnetic waves and the plasma is still a challenging topic due to the different time and space scales involved. In this article, an Alternative Direction Implicit (ADI) formulation of the Finite Difference Time Domain method for solving Maxwell's equations coupled with a simplified plasma model via the electric current is being proposed, leading to a significant reduction of the computational cost as the CFL criterion for stability of the FDTD method is being removed. An energy estimate has been used to prove the unconditional stability of the ADI-FDTD leapfrog scheme as well as its coupled formulation. The computational efficiency and accuracy of this approach has been studied in a simplified case. The proposed method is applied and validated in two dimensional microwave breakdown in air while its computational efficiency allows for fully three dimensional simulations, an important step for understanding the complex nature and evolution of a microwave plasma discharge and its possible applicability as an aerodynamic flow control method.

  4. Detection of x-ray emission in a nanosecond discharge in air at atmospheric pressure.

    PubMed

    Zhang, Cheng; Shao, Tao; Yu, Yang; Niu, Zheng; Yan, Ping; Zhou, Yuanxiang

    2010-12-01

    Measurement of x-ray emission is an important parameter to investigate runaway behavior of fast electrons produced in nanosecond-pulse gas discharge. An online detection system of x rays is described in this paper, and the system consists of an x-ray detector with NaI (Tl) scintillator and photomultiplier tube, and an integrated multichannel analyzer. The system is responsible for detecting x-ray emission signal, processing the detected signals, and scaling the energy distribution. The calibration results show that every channel of the detection system represents a given x-ray energy and various x rays can be divided into different energy ranges between 10 and 130 keV. For a repetitive nanosecond-pulse breakdown between highly nonuniform gaps in open air, an energy distribution is obtained using the online detection system. It shows that the x-ray emission is a continuous spectrum and the x rays of above 60 keV dominate in the detected energy distribution. PMID:21198017

  5. Mechanism of Ethane Destruction in Dielectric Barrier Discharge in Air: Detailed Elementary Reaction Model and Experiment

    NASA Astrophysics Data System (ADS)

    Krasnoperov, Lev; Modenese, Camila; Krishtopa, Larisa

    2006-10-01

    Free radical destruction mechanism was extended by inclusion of reactions of excited and ionic species. The mechanism consists of 935 reactions of 85 neutral species, 9 excited states and 38 ions. The reactions include 9 initiation processes in streamers, 66 processes involving excited states and 83 reactions involving ions. The reactant, the final products as well as the major intermediates of the destruction of ethane in air in corona discharge were identified and quantified Carbon dioxide (CO2), water (H2O), formaldehyde (H2CO), acetaldehyde (CH3CHO), methanol (CH3OH), ethanol (C2H5OH), formic acid (HCOOH), acetic acid (CH3COOH), methyl nitrate (CH3ONO2) and ethyl nitrate (C2H5ONO2) were identified among the major destruction products. The destruction efficiency predicted by the mechanism is in good agreement with the experiment, the major contribution is being due to the ionization transfer reactions. Reactions of excited species play but only a minor role. The product spectrum is consistent with the subsequent low temperature free radical reactions complicated by the presence of ozone and nitrogen oxides. The generic reaction mechanism for other organic as well as inorganic compounds is discussed.

  6. Streamer development in barrier discharge in air: spectral signatures and electric field

    NASA Astrophysics Data System (ADS)

    Hoder, Tomas; Simek, Milan; Bonaventura, Zdenek; Prukner, Vaclav

    2015-09-01

    Electrical breakdown in the upper atmosphere takes form of so called Transient Luminous Events (TLE). Down to the certain pressure limit, the first phases of the TLE-phenomena are controlled by the streamer mechanism. In order to understand the development of these events, streamers in 10 torr air were generated in volume barrier discharge. Stability and reproducibility of generated streamers were secured by proper electrode geometry and specific applied voltage waveform. In this work, spectrally resolved measurements of the streamer head emission with high spatial and temporal resolution are presented. Precise recordings of the emission of the second positive and first negative systems of molecular nitrogen allowed the determination of the spatio-temporal development of the reduced electric field in the streamer head. This unique experimental result reveals in more details the early stages of the streamer development and gives, besides values for streamer velocity and its diameter, quantitative information on the magnitude of the electric field. T.H. was financed through the ESF Programme TEA-IS (Grant No. 4219), M.S. and V.P. by the AVCR under collaborative project M100431201 and Z.B. acknowledges the support of grant of Czech Science Foundation GA15-04023S.

  7. Study of the homogeneity of the current distribution in a dielectric barrier discharge in air by means of a segmented electrode

    NASA Astrophysics Data System (ADS)

    Malashin, M. V.; Moshkunov, S. I.; Khomich, V. Yu.

    2016-02-01

    The current distribution in a dielectric barrier discharge in atmospheric-pressure air at a natural humidity of 40-60% was studied experimentally with a time resolution of 200 ps. The experimental results are interpreted by means of numerically simulating the discharge electric circuit. The obtained results indicate that the discharge operating in the volumetric mode develops simultaneously over the entire transverse cross section of the discharge gap.

  8. Gap-dependent arrangements of dielectric barrier discharges in open air

    SciTech Connect

    Chu, Hong-Yu; Liou, Bang-Tsui

    2014-08-15

    Investigations of the structural arrangement of the atmospheric filamentary discharges were carried out. By observing the initial discharge events, we find that the surface charge plays a significant role of seeding electrons. The filamentary discharges show ordered and disordered patterns in parallel plates with different gap distances. A critical gap distance for an ordered pattern is found at about 700 μm. The transition of the order-disorder discharge pattern is also confirmed in a wedged-plates setup with a continuous change of gap distance. The bond-orientational function of the structure of the pattern is related to the mutual Coulomb interaction between discharges.

  9. Numerical Investigation of Flow in a Centrifugal Compressor

    NASA Astrophysics Data System (ADS)

    Grishin, Yu. A.; Bakulin, V. N.

    2015-09-01

    With the use of the domestic software suite of computational hydrodynamics Flow Vision based on application of the method of control volumes, numerical simulation of air composition and delivery by a centrifugal compressor employed for supercharging a piston engine has been carried out. The head-flow characteristics of the compressor, as well as the 3D fields of flow velocity and pressure distributions in the elements of the compressor flow passage, including the interblade channels of the impeller, have been obtained for various regimes. In the regimes of diminished air flow rate, surging phenomena are identified, characterized by a return flow. The application of the technique of numerical experiment will make it possible from here on to carry out design optimization of the compressor flow passage profile and thus to improve its basic characteristics — the degree of pressure increase, compressed air flow rate, and the efficiency — as well as to reduce the costs of the development and production of compressors.

  10. Femtosecond laser guiding of a high-voltage discharge and the restoration of dielectric strength in air and nitrogen

    SciTech Connect

    Leonov, S. B.; Firsov, A. A.; Shurupov, M. A.; Michael, J. B.; Shneider, M. N.; Miles, R. B.; Popov, N. A.

    2012-12-15

    The use of a low energy, high peak intensity (>100 TW/cm{sup 2}) femtosecond laser pulse is investigated for guiding and control of a sub-microsecond high voltage discharge. Study of the laser induced plasma channel and measurements of the field required for breakdown in air and nitrogen at atmospheric pressure are presented. Direct imaging of the dynamics of the discharge breakdown shows effective laser guiding. The effectiveness of laser guiding is shown to be critically dependent on the laser focusing geometry, timing, and location relative to the electrodes.

  11. Femtosecond laser guiding of a high-voltage discharge and the restoration of dielectric strength in air and nitrogen

    NASA Astrophysics Data System (ADS)

    Leonov, S. B.; Firsov, A. A.; Shurupov, M. A.; Michael, J. B.; Shneider, M. N.; Miles, R. B.; Popov, N. A.

    2012-12-01

    The use of a low energy, high peak intensity (>100 TW/cm2) femtosecond laser pulse is investigated for guiding and control of a sub-microsecond high voltage discharge. Study of the laser induced plasma channel and measurements of the field required for breakdown in air and nitrogen at atmospheric pressure are presented. Direct imaging of the dynamics of the discharge breakdown shows effective laser guiding. The effectiveness of laser guiding is shown to be critically dependent on the laser focusing geometry, timing, and location relative to the electrodes.

  12. Ionic wind generation by a wire-cylinder-plate corona discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Colas, Dorian F.; Ferret, Antoine; Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-11-01

    A wire-cylinder-plate electrode configuration is presented to generate ionic wind with a dc corona discharge in air at atmospheric pressure. The objective of the work is to maximize the power supplied to the flow in order to increase acceleration while avoiding breakdown. Thus, the proposed experimental setup addresses the problem of decoupling the mechanism of ion generation from that of ion acceleration. Using a wire-plate configuration as a reference, we have focused on improving the topography of the electric field to (1) separate the ionization and acceleration zones in space, and (2) guide the trajectory of charged particles as parallel to the median axis as possible. In the proposed wire-cylinder-plate setup, a dc corona discharge is generated in the space between a wire and two cylinders. The ions produced by the corona then drift past the cylinders and into a channel between two plates, where they undergo acceleration. To maximize the ionic wind it is found that the geometric configuration must be as compact as possible and that the voltage applied must be right below breakdown. Experimentally, the optimized wire-plate reference setup provides a maximum flow velocity of 8 m s-1, a flow rate per unit electrode length of 0.034 m2 s-1, and a thrust per unit electrode length of 0.24 N m-1. The wire-cylinder-plate configuration provides a maximum flow velocity of 10 m s-1, a flow rate per unit electrode length of 0.041 m2 s-1, and a thrust per unit electrode length of 0.35 N m-1. This 46% increase in thrust is obtained by increasing the electric power per unit electrode length by only 16% (from 175 to 210 W m-1), which confirms the gain in efficiency obtained with the decoupled system. In comparison with a simple wire-wire corona configuration, the wire-cylinder-plate configuration increases the ionic wind velocity by up to a factor of 3, and the thrust by an order of magnitude.

  13. Simple method of determining plasma impedance of streamer discharge in atmospheric air.

    PubMed

    Okano, Daisuke

    2011-12-01

    For atmospheric streamer discharges using a lightning impulse generator, we demonstrate a method of determining the plasma impedance in a streamer region by analyzing the periodic attenuated discharge waveforms having high-frequency components. When the streamer region in the plasma can be treated as an equivalent series circuit model including resistance and inductance elements, the regression waveforms obtained by reducing and smoothing the discharge waveforms are analyzed in the equivalent circuit. We found that the streamer resistance increased exponentially with time after the discharge, whereas the streamer inductance and series impedance were constant at 4.0 Ω for longer than the first period of the discharge waveforms. Moreover, the slope of the regression curve increases more rapidly for the positive streamer resistance than for the negative resistance. Finally, the absolute values of the streamer impedance versus time were 3.3-19 Ω and 3.5-9.0 Ω for positive and negative discharges, respectively. PMID:22225214

  14. Optical and application study of gas-liquid discharge excited by bipolar nanosecond pulse in atmospheric air

    NASA Astrophysics Data System (ADS)

    Wang, Sen; Wang, Wen-chun; Yang, De-zheng; Liu, Zhi-jie; Zhang, Shuai

    2014-10-01

    In this study, a bipolar nanosecond pulse with 20 ns rising time is employed to generate air gas-liquid diffuse discharge plasma with room gas temperature in quartz tube at atmospheric pressure. The image of the discharge and optical emission spectra of active species in the plasma are recorded. The plasma gas temperature is determined to be approximately 390 K by compared the experimental spectra with the simulated spectra, which is slightly higher than the room temperature. The result indicated that the gas temperature rises gradually with pulse peak voltage increasing, while decreases slightly with the electrode gap distance increasing. As an important application, bipolar nanosecond pulse discharge is used to sterilize the common microorganisms (Actinomycetes, Candida albicans and Escherichia coli) existing in drinking water, which performs high sterilization efficiency.

  15. Dynamics of the microstructure of current channels and the generation of high-energy electrons in nanosecond discharges in air

    SciTech Connect

    Karelin, V. I.; Trenkin, A. A. Fedoseev, I. G.

    2015-12-15

    The results of the three-dimensional numerical simulation of the dynamics of the microstructure of high-voltage nanosecond discharges in air at atmospheric pressure are presented. It is established that the fast (at a time of ≈10 ns) broadening and significant decrease in the gas concentration in the microchannels occur as a result of the ohmic heating of microchannels with the diameter of 1–30 μm. It was shown that the broadening of microchannels in a nanosecond diffusive discharge provides an increase in the ratio of the electric field strength to the gas concentration in microchannels to values sufficient for the generation highenergy electron beams and X-ray bremsstrahlung in them. Features of the dynamics of the system of microchannels and its effect on the efficiency of the generation of high-energy electrons in discharges developing in the microstructuring regime of the current channels are considered.

  16. The importance of corona generation and leader formation during laser filament guided discharges in air

    NASA Astrophysics Data System (ADS)

    Schmitt-Sody, Andreas; French, David; White, William; Lucero, Adrian; Roach, William P.; Hasson, Victor

    2015-03-01

    Images taken with an intensified CCD camera show the dynamics during filament guided discharge events. The images reveal that filament initiated corona plays a role in the presented results. Furthermore, the images show the formation of leaders, propagating and eventually bridging the gap between the high voltage (HV) electrodes. Analysis of the images and comparison to oscilloscope traces of voltage and current dynamics reveal the origin of the delay between the filament and HV discharge and allows for a probability of discharge analysis.

  17. Study on Mechanism Analysis and Motion Simulation of the Scroll Compressor

    NASA Astrophysics Data System (ADS)

    Su, Donghai; Wang, Zhijun

    In this paper, according to the application practice of scroll compressor for refrigeration and air-conditioning, various factors affecting the whole refrigeration effect of the compressor are studied, the influence of scroll wrap's different forms on compressor exhaust angle and the compression ratio is stated, and it establishes the working principle simulation of the compressor's main parts, and further corrects the form of vortex lines according to simulation results.

  18. Simultaneous measurements of wire electrode surface contamination and corona discharge characteristics in an air-cleaning electrostatic precipitator

    SciTech Connect

    Kanazawa, Seiji; Ohkubo, Toshikazu; Nomoto, Yukiharu; Adachi, Takayoshi; Chang, J.S.

    1997-01-01

    Contamination of the corona wire in a wire-to-plate type air-cleaning electrostatic precipitator is studied experimentally. In order to enhance the contamination of wire, air containing dusts is directly supplied to a part of the wire electrode. Spores of Lycopodium and cigarette smoke particles are used as test dusts. Simultaneous measurements of wire electrode optical images and corona discharge modes are carried out during contamination processes. Results show that corona discharge modes and optical emission from the wire electrode change with time due to the surface contamination. In the case of cigarette smoke, after a time elapsed, streamer coronas appear due to the buildup of smoke particles on the wire surface. After the first streamer generation, the corona current fluctuates with time because the formation and diminution of the projections occur alternately at the different parts on the wire electrode surface.

  19. Development of a diffuse air-argon plasma source using a dielectric-barrier discharge at atmospheric pressure

    SciTech Connect

    Tang Jie; Jiang Weiman; Zhao Wei; Wang Yishan; Li Shibo; Wang Haojing; Duan Yixiang

    2013-01-21

    A stable diffuse large-volume air plasma source was developed by using argon-induced dielectric-barrier discharges at atmospheric pressure. This plasma source can be operated in a filamentary discharge with the average areal power density of 0.27 W/cm{sup 2} and the gas temperature of 315{+-}3 K. Spatial measurement of emission spectrum and temperature indicates that this plasma is uniform in the central region along the transverse direction. It is also found that the formation of diffuse air plasma mainly lies in the creation of sufficient seed electrons by the Penning effect through collisions between two argon or nitrogen metastables at low electric fields.

  20. Ozone generation by negative direct current corona discharges in dry air fed coaxial wire-cylinder reactors

    SciTech Connect

    Yehia, Ashraf; Mizuno, Akira

    2013-05-14

    An analytical study was made in this paper for calculating the ozone generation by negative dc corona discharges. The corona discharges were formed in a coaxial wire-cylinder reactor. The reactor was fed by dry air flowing with constant rates at atmospheric pressure and room temperature, and stressed by a negative dc voltage. The current-voltage characteristics of the negative dc corona discharges formed inside the reactor were measured in parallel with concentration of the generated ozone under different operating conditions. An empirical equation was derived from the experimental results for calculating the ozone concentration generated inside the reactor. The results, that have been recalculated by using the derived equation, have agreed with the experimental results over the whole range of the investigated parameters, except in the saturation range for the ozone concentration. Therefore, the derived equation represents a suitable criterion for expecting the ozone concentration generated by negative dc corona discharges in dry air fed coaxial wire-cylinder reactors under any operating conditions in range of the investigated parameters.

  1. An atmospheric air gas-liquid diffuse discharge excited by bipolar nanosecond pulse in quartz container used for water sterilization

    NASA Astrophysics Data System (ADS)

    Wang, Sen; Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Liu, Zhi-Jie; Tang, Kai; Song, Ying

    2013-12-01

    In this Letter, we report that the air gas-liquid diffuse discharge plasma excited by bipolar nanosecond pulse in quartz container with different bottom structures at atmospheric pressure. Optical diagnostic measurements show that bountiful chemically and biologically active species, which are beneficial for effective sterilization in some areas, are produced. Such diffuse plasmas are then used to treat drinking water containing the common microorganisms (Candida albicans and Escherichia coli). It is found that these plasmas can sterilize the microorganisms efficiently.

  2. Controlled electrochemical etching of nanoporous Si anodes and its discharge behavior in alkaline Si-air batteries.

    PubMed

    Park, Dong-Won; Kim, Soeun; Ocon, Joey D; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2015-02-11

    We report the fabrication of nanoporous silicon (nPSi) electrodes via electrochemical etching to form a porous Si layer with controllable thickness and pore size. Varying the etching time and ethanolic HF concentration results in different surface morphologies, with various degrees of electrolyte access depending on the pore characteristics. Optimizing the etching condition leads to well-developed nPSi electrodes, which have thick porous layers and smaller pore diameter and exhibit improved discharge behavior as anodes in alkaline Si-air cells in contrast to flat Si anode. Although electrochemical etching is effective in improving the interfacial characteristics of Si in terms of high surface area, we observed that mild anodization occurs and produces an oxide overlayer. We then show that this oxide layer in nPSi anodes can be effectively removed to produce an nPSi anode with good discharge behavior in an actual alkaline Si-air cell. In the future, the combination of high surface area nPSi anodes with nonaqueous electrolytes (e.g., room-temperature ionic liquid electrolyte) to minimize the strong passivation behavior and self-discharge in Si could lead to Si-air cells with a stable voltage profile and high anode utilization. PMID:25594400

  3. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-05-01

    In atmospheric pressure air preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determined, with the notable result that there exists a minimum and maximum gap distance for its existence at a given ambient gas temperature. The minimum gap distance increases with decreasing gas temperature, whereas the maximum does not vary appreciably. To explain the experimental results, an analytical model is developed to explain the corona-to-glow (C-G) and glow-to-spark (G-S) transitions. The C-G transition is analyzed in terms of the avalanche-to-streamer transition and the breakdown field during the conduction phase following the establishment of a conducting channel across the discharge gap. The G-S transition is determined by the thermal ionization instability, and we show analytically that this transition occurs at a certain reduced electric field for the NRP discharges studied here. This model shows that the electrode geometry plays an important role in the existence of the NRP glow regime at a given gas temperature. We derive a criterion for the existence of the NRP glow regime as a function of the ambient gas temperature, pulse repetition frequency, electrode radius of curvature, and interelectrode gap distance.

  4. Discharge properties of Mg-Al-Mn-Ca and Mg-Al-Mn alloys as anode materials for primary magnesium-air batteries

    NASA Astrophysics Data System (ADS)

    Yuasa, Motohiro; Huang, Xinsheng; Suzuki, Kazutaka; Mabuchi, Mamoru; Chino, Yasumasa

    2015-11-01

    The discharge behaviors of rolled Mg-6 mass%Al-0.3 mass%Mn-2 mass%Ca (AMX602) and Mg-6 mass%Al-0.3 mass%Mn (AM60) alloys used as anodes for Magnesium-air batteries were investigated. The AMX602 alloy exhibited superior discharge properties compared to the AM60 alloy, especially at low current density. The discharge products of the AMX602 alloy were dense and thin, and many cracks were observed at all current densities. In addition, the discharge products were detached at some sites. These sites often corresponded to the positions of Al2Ca particles. The comparison of the discharge and corrosion tests indicated that the dense and thin discharge products of AMX602 were easily cracked by dissolution of the Mg matrix around Al2Ca particles, and the cracks promoted the penetration of the electrolyte into the discharge products, retaining the discharge activity. In contrast, concerning the AM60 alloy, thick discharge products were formed on the surface during discharge, and cracking of the discharge products hardly occurred, degrading the discharge properties. Localized and deeply corroded pits that could result from the detachment of metal pieces from the anode during discharge were partly observed in the AM60 alloy. It is suggested that these detached metal pieces are another reason for the low discharge properties of the AM60 alloy.

  5. Seneca Compressed Air Energy Storage (CAES) Project

    SciTech Connect

    2012-11-30

    This document provides specifications for the process air compressor for a compressed air storage project, requests a budgetary quote, and provides supporting information, including compressor data, site specific data, water analysis, and Seneca CAES value drivers.

  6. Evaluation of centrifugal compressor performance with water injection

    NASA Technical Reports Server (NTRS)

    Beede, William L; Hamrick, Joseph T; Withee, Joseph R , Jr

    1951-01-01

    The effects of water injection on a compressor are presented. To determine the effects of varying water-air ratio, the compressor was operated at a constant equivalent impeller speed over a range of water-air ratios and weight flows. Operation over a range of weight flows at one water-air ratio and two inlet air temperatures was carried out to obtain an indication of the effects of varying inlet air temperature. Beyond a water-air ratio of 0.03 there was no increase in maximum air-weight flow, a negligible rise in peak total-pressure ratio, and a decrease in peak adiabatic efficiency. An increase in inlet air temperature resulted in an increase in the magnitude of evaporation. An analysis of data indicated that the magnitude of evaporation within the compressor impeller was small.

  7. Compressor Stall Recovery Through Tip Injection Assessed

    NASA Technical Reports Server (NTRS)

    Suder, Ken L.

    2001-01-01

    Aerodynamic stability is a fundamental limit in the compressor design process. The development of robust techniques for increasing stability has several benefits: enabling higher loading and fewer blades, increasing safety throughout a mission, increasing tolerance to stage mismatch during part-speed operation and speed transients, and providing an opportunity to match stages at the compressor maximum efficiency point, thus reducing fuel burn. Mass injection upstream of the tip of a high-speed axial compressor rotor is a stability enhancement approach known to be effective in suppressing stall in tip-critical rotors if the injection is activated before stall occurs. This approach to stall suppression requires that a reliable stall warning system be available. Tests have recently been performed to assess whether steady injection can also be used to recover from fully developed stall. If mass injection is effective in recovering from stall quickly enough to avoid structural damage or loss of engine power, then a stall warning system may not be required. The stall recovery tests were performed on a transonic compressor rotor at its design tip speed of 1475 ft/sec using four injectors evenly spaced around the compressor case upstream of the rotor. The injectors were connected to an external air source. In an actual engine application, the injected air would be supplied with compressor bleed air. The injectors were isolated from the air source by a fast-acting butterfly valve. With the injectors turned off, the compressor was throttled into stall. Air injection was then activated with no change in throttle setting by opening the butterfly valve. The compressor recovered from stall at a fixed throttle setting with the aid of tip injection. The unsteady operating characteristic of the rotor was measured during these tests using high-response pressure sensors located upstream and downstream of the rotor. The figure shows the results, where the unsteady pressure and mass

  8. Cold-air performance of the compressor-drive turbine of the Department of Energy baseline automobile gas-turbine engine

    NASA Technical Reports Server (NTRS)

    Roelke, R. J.; Mclallin, K. L.

    1978-01-01

    The aerodynamic performance of the compressor-drive turbine of the DOE baseline gas-turbine engine was determined over a range of pressure ratios and speeds. In addition, static pressures were measured in the diffusing transition duct located immediately downstream of the turbine. Results are presented in terms of mass flow, torque, specific work, and efficiency for the turbine and in terms of pressure recovery and effectiveness for the transition duct.

  9. 110. COMPRESSOR FOR REFRIGERANT COOLING BY WEST WALL OF MECHANICAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    110. COMPRESSOR FOR REFRIGERANT COOLING BY WEST WALL OF MECHANICAL EQUIPMENT ROOM (201), LSB (BLDG. 751) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  10. Bidirectional grating compressors

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Li, Zhaoyang; Li, Shuai; Liu, Yanqi; Leng, Yuxin; Li, Ruxin

    2016-07-01

    A bidirectional grating compressor for chirped pulse amplifiers is presented. It compresses a laser beam simultaneously in two opposite directions. The pulse compressor is shown to promote chirped pulse amplifiers' output energy without grating damages. To verify the practicability, an experiment is carried out. In addition, a crosscorrelation instrument is designed and set up to test the time synchronization between these two femtosecond pulses.

  11. 30 CFR 75.344 - Compressors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... air course or to the surface and equipped with sensors to monitor for heat and for carbon monoxide or smoke. The sensors shall deenergize power to the compressor, activate a visual and audible alarm located... every 31 days, sensors installed to monitor for carbon monoxide shall be calibrated with a...

  12. 30 CFR 75.344 - Compressors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air course or to the surface and equipped with sensors to monitor for heat and for carbon monoxide or smoke. The sensors shall deenergize power to the compressor, activate a visual and audible alarm located... every 31 days, sensors installed to monitor for carbon monoxide shall be calibrated with a...

  13. 30 CFR 75.344 - Compressors.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air course or to the surface and equipped with sensors to monitor for heat and for carbon monoxide or smoke. The sensors shall deenergize power to the compressor, activate a visual and audible alarm located... every 31 days, sensors installed to monitor for carbon monoxide shall be calibrated with a...

  14. 30 CFR 75.344 - Compressors.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air course or to the surface and equipped with sensors to monitor for heat and for carbon monoxide or smoke. The sensors shall deenergize power to the compressor, activate a visual and audible alarm located... every 31 days, sensors installed to monitor for carbon monoxide shall be calibrated with a...

  15. 30 CFR 75.344 - Compressors.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air course or to the surface and equipped with sensors to monitor for heat and for carbon monoxide or smoke. The sensors shall deenergize power to the compressor, activate a visual and audible alarm located... every 31 days, sensors installed to monitor for carbon monoxide shall be calibrated with a...

  16. Supersonic gas compressor

    DOEpatents

    Lawlor, Shawn P.; Novaresi, Mark A.; Cornelius, Charles C.

    2007-11-13

    A gas compressor based on the use of a driven rotor having a compression ramp traveling at a local supersonic inlet velocity (based on the combination of inlet gas velocity and tangential speed of the ramp) which compresses inlet gas against a stationary sidewall. In using this method to compress inlet gas, the supersonic compressor efficiently achieves high compression ratios while utilizing a compact, stabilized gasdynamic flow path. Operated at supersonic speeds, the inlet stabilizes an oblique/normal shock system in the gasdyanamic flow path formed between the rim of the rotor, the strakes, and a stationary external housing. Part load efficiency is enhanced by the use of a pre-swirl compressor, and using a bypass stream to bleed a portion of the intermediate pressure gas after passing through the pre-swirl compressor back to the inlet of the pre-swirl compressor. Inlet guide vanes to the compression ramp enhance overall efficiency.

  17. Compressor surge control method

    SciTech Connect

    Dziubakowski, D.J.; Keys, M.A.I.V.; Shaffer, J.J.

    1990-02-13

    This patent describes a method of controlling surge in a centrifugal compressor having a predetermined surge condition line and providing a combined output with a base load means. It comprises: establishing a main surge control line offset from the centrifugal compressor surge condition line according to a function of pressure differentials across the centrifugal compressor and across an orifice in the inlet line of the centrifugal compressor; establishing a feed forward control signal which is a function of a variable associated with the base load means which may cause the surge condition in the centrifugal compressor; and establishing an anticipatory surge control line offset from the main surge control line as a function of the established main surge control line and the established feed forward control signal.

  18. Effect of dielectric material on bipolar nanosecond pulse diffuse dielectric barrier discharge in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Wang, Wenchun; Yang, Dezheng; Zhang, Shuai; Yang, Yang; Liu, Zhijie

    2013-08-01

    In this paper, dielectric plates made by ceramic, quartz and polytetrafluoroethylene (PTFE) respectively are employed to generate low gas temperature, diffuse dielectric barrier discharge plasma by using a needle-plate electrode configuration in air at atmospheric pressure. Both discharge images and the optical emission spectra are obtained while ceramic, quartz and PTFE are used as dielectric material. Plasma gas temperature is also calculated by comparing the experimental emission spectra with the best fitted spectra of N2 (C3Πu → B3Πg 1-3) and N2 (C3Πu → B3Πg 0-2). The effects of different pulse peak voltages and gas gap distances on the emission intensity of N2 (C3Πu → B3Πg, 0-0, 337.1 nm) and the plasma area on dielectric surface are investigated while ceramic, quartz and PTFE are used as dielectric material. It is found that the permittivity of dielectric material plays an important role in the discharge homogeneity, plasma gas temperature, emission spectra intensity of the discharge, etc. Dielectric with higher permittivity i.e., ceramic means brighter discharge luminosity and stronger emission spectra intensity of N2 (C3Πu → B3Πg, 0-0, 337.1 nm) among the three dielectric materials. However, more homogeneous, larger plasma area on dielectric surface and lower plasma gas temperature can be obtained under dielectric with lower permittivity i.e., PTFE. The emission spectra intensity and plasma gas temperature of the discharge while the dielectric plate is made by quartz are smaller than that while ceramic is used as dielectric material and bigger than that when PTFE is used as dielectric material.

  19. Effect of dielectric material on bipolar nanosecond pulse diffuse dielectric barrier discharge in air at atmospheric pressure.

    PubMed

    Tang, Kai; Wang, Wenchun; Yang, Dezheng; Zhang, Shuai; Yang, Yang; Liu, Zhijie

    2013-08-01

    In this paper, dielectric plates made by ceramic, quartz and polytetrafluoroethylene (PTFE) respectively are employed to generate low gas temperature, diffuse dielectric barrier discharge plasma by using a needle-plate electrode configuration in air at atmospheric pressure. Both discharge images and the optical emission spectra are obtained while ceramic, quartz and PTFE are used as dielectric material. Plasma gas temperature is also calculated by comparing the experimental emission spectra with the best fitted spectra of N2 (C(3)Πu→B(3)Πg 1-3) and N2 (C(3)Πu→B(3)Πg 0-2). The effects of different pulse peak voltages and gas gap distances on the emission intensity of N2 (C(3)Πu→B(3)Πg, 0-0, 337.1 nm) and the plasma area on dielectric surface are investigated while ceramic, quartz and PTFE are used as dielectric material. It is found that the permittivity of dielectric material plays an important role in the discharge homogeneity, plasma gas temperature, emission spectra intensity of the discharge, etc. Dielectric with higher permittivity i.e., ceramic means brighter discharge luminosity and stronger emission spectra intensity of N2 (C(3)Πu→B(3)Πg, 0-0, 337.1 nm) among the three dielectric materials. However, more homogeneous, larger plasma area on dielectric surface and lower plasma gas temperature can be obtained under dielectric with lower permittivity i.e., PTFE. The emission spectra intensity and plasma gas temperature of the discharge while the dielectric plate is made by quartz are smaller than that while ceramic is used as dielectric material and bigger than that when PTFE is used as dielectric material. PMID:23673240

  20. Pulsed nanosecond discharge in air at high specific deposited energy: fast gas heating and active particle production

    NASA Astrophysics Data System (ADS)

    Popov, N. A.

    2016-08-01

    The results of a numerical study on kinetic processes initiated by a pulsed nanosecond discharge in air at high specific deposited energy, when the dissociation degree of oxygen molecules is high, are presented. The calculations of the temporal dynamics of the electron concentration, density of atomic oxygen, vibrational distribution function of nitrogen molecules, and gas temperature agree with the experimental data. It is shown that quenching of electronically excited states of nitrogen N2(B3Πg), N2(С3Πu), N2(a‧1 Σ \\text{u}- ) by oxygen molecules leads to the dissociation of O2. This conclusion is based on the comparison of calculated dynamics of atomic oxygen in air, excited by a pulsed nanosecond discharge, with experimental data. In air plasma at a high dissociation degree of oxygen molecules ([O]/[O2]  >  10%), relaxation of the electronic energy of atoms and molecules in reactions with O atoms becomes extremely important. Active production of NO molecules and fast gas heating in the discharge plasma due to the quenching of electronically excited N2(B3Πg, C3Πu, a‧1 Σ \\text{u}- ) molecules by oxygen atoms is notable. Owing to the high O atom density, electrons are effectively detached from negative ions in the discharge afterglow. As a result, the decay of plasma in the afterglow is determined by electron–ion recombination, and the electron density remains relatively high between the pulses. An increase in the vibrational temperature of nitrogen molecules at the periphery of the plasma channel at time delay t  =  1–30 μs after the discharge is obtained. This is due to intense gas heating and, as a result, gas-dynamic expansion of a hot gas channel. Vibrationally excited N2(v) molecules produced near the discharge axis move from the axial region to the periphery. Consequently, at the periphery the vibrational temperature of nitrogen molecules is increased.

  1. Prolongation of the lifetime of guided discharges triggered in atmospheric air by femtosecond laser filaments up to 130 μs

    NASA Astrophysics Data System (ADS)

    Arantchouk, L.; Honnorat, B.; Thouin, E.; Point, G.; Mysyrowicz, A.; Houard, A.

    2016-04-01

    The triggering and guiding of electric discharges produced in atmospheric air by a compact 100 kV Marx generator is realized in laboratory using an intense femtosecond laser pulse undergoing filamentation. We describe here an approach allowing extending the lifetime of the discharges by injecting a current with an additional circuit. Laser guiding discharges with a length of 8.5 cm and duration of 130 μs were obtained.

  2. Interferometric and schlieren characterization of the plasmas and shock wave dynamics during laser-triggered discharge in atmospheric air

    SciTech Connect

    Wei, Wenfu; Li, Xingwen Wu, Jian; Yang, Zefeng; Jia, Shenli; Qiu, Aici

    2014-08-15

    This paper describes our efforts to reveal the underlying physics of laser-triggered discharges in atmospheric air using a Mach-Zehnder interferometer and schlieren photography. Unlike the hemispherical shock waves that are produced by laser ablation, bell-like morphologies are observed during laser-triggered discharges. Phase shifts are recovered from the interferograms at a time of 1000 ns by the 2D fast Fourier transform method, and then the values of the refractive index are deduced using the Abel inversion. An abundance of free electrons is expected near the cathode surface. The schlieren photographs visualize the formation of stagnation layers at ∼600 ns in the interaction zones of the laser- and discharge-produced plasmas. Multiple reflected waves are observed at later times with the development of shock wave propagations. Estimations using the Taylor-Sedov self-similar solution indicated that approximately 45.8% and 51.9% of the laser and electrical energies are transferred into the gas flow motions, respectively. Finally, numerical simulations were performed, which successfully reproduced the main features of the experimental observations, and provided valuable insights into the plasma and shock wave dynamics during the laser-triggered discharge.

  3. Method and apparatus for starting supersonic compressors

    DOEpatents

    Lawlor, Shawn P.

    2012-04-10

    A supersonic gas compressor. The compressor includes aerodynamic duct(s) situated on a rotor journaled in a casing. The aerodynamic duct(s) generate a plurality of oblique shock waves for efficiently compressing a gas at supersonic conditions. The convergent inlet is adjacent to a bleed air collector, and during acceleration of the rotor, bypass gas is removed from the convergent inlet via a collector to enable supersonic shock stabilization. Once the oblique shocks are stabilized at a selected inlet relative Mach number and pressure ratio, the bleed of bypass gas from the convergent inlet via the bypass gas collectors is eliminated.

  4. Ozone generation in a kHz-pulsed He-O2 capillary dielectric barrier discharge operated in ambient air

    NASA Astrophysics Data System (ADS)

    Sands, Brian L.; Ganguly, Biswa N.

    2013-12-01

    The generation of reactive oxygen species using nonequilibrium atmospheric pressure plasma jet devices has been a subject of recent interest due to their ability to generate localized concentrations from a compact source. To date, such studies with plasma jet devices have primarily utilized radio-frequency excitation. In this work, we characterize ozone generation in a kHz-pulsed capillary dielectric barrier discharge configuration comprised of an active discharge plasma jet operating in ambient air that is externally grounded. The plasma jet flow gas was composed of helium with an admixture of up to 5% oxygen. A unipolar voltage pulse train with a 20 ns pulse risetime was used to drive the discharge at repetition rates between 2-25 kHz. Using UVLED absorption spectroscopy centered at 255 nm near the Hartley-band absorption peak, ozone was detected over 1 cm from the capillary axis. We observed roughly linear scaling of ozone production with increasing pulse repetition rate up to a "turnover frequency," beyond which ozone production steadily dropped and discharge current and 777 nm O(5P→5S°) emission sharply increased. The turnover in ozone production occurred at higher pulse frequencies with increasing flow rate and decreasing applied voltage with a common energy density of 55 mJ/cm3 supplied to the discharge. The limiting energy density and peak ozone production both increased with increasing O2 admixture. The power dissipated in the discharge was obtained from circuit current and voltage measurements using a modified parallel plate dielectric barrier discharge circuit model and the volume-averaged ozone concentration was derived from a 2D ozone absorption measurement. From these measurements, the volume-averaged efficiency of ozone production was calculated to be 23 g/kWh at conditions for peak ozone production of 41 mg/h at 11 kV applied voltage, 3% O2, 2 l/min flow rate, and 13 kHz pulse repetition rate, with 1.79 W dissipated in the discharge.

  5. Erosion of a-C:H films deposited on W, Mo, and stainless steel under interaction with air glow discharge

    NASA Astrophysics Data System (ADS)

    Zalavutdinov, R. Kh.; Gorodetsky, A. E.; Bukhovets, V. L.; Zakharov, A. P.; Mazul, I. V.

    2011-08-01

    An air direct current glow discharge with a hollow cathode was used as source of chemically active oxygen for selective removal of amorphous hydrogenated (a-C:H) films deposited on W, Mo, and stainless steel. The films were removed both directly in the discharge and afterglow region. The film erosion rates depend on the sample position relatively to plasma and decrease in the order: hollow cathode, positive column, afterglow region. It was shown that primary (1-3 nm) continuous amorphous and secondary (1-30 nm) island-like oxide films were formed on the metal surfaces after removal of the a-C:H films. Polycrystalline island-like oxide films were generated due to recrystallization of the primary films. Material oxidation suppression was caused by reactions of oxygen ion neutralization and atomic oxygen recombination on metals.

  6. Effects of Environmental Humidity and Temperature on Sterilization Efficiency of Dielectric Barrier Discharge Plasmas in Atmospheric Pressure Air

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yusuke; Miyamae, Masanori; Nagata, Masayoshi; Fukumoto, Naoyuki

    2011-01-01

    The inactivation of Bacillus atrophaeus spores by a dielectric barrier discharge (DBD) plasma in atmospheric humid air was investigated in order to develop a low-temperature, low-cost, and high-speed plasma sterilization technique. The biological indicators covered with a Tyvek sheet were set just outside the DBD plasma region, where air temperature and humidity as a discharge gas were precisely controlled by an environmental test chamber. The results show that the inactivation of B. atrophaeus spores was found to be dependent strongly on humidity, and was completed within 15 min at a relative humidity of 90% and a temperature of 30 °C. The treatment time for sterilization is shorter than those of conventional sterilization methods using ethylene oxide gas and dry heat treatment. The inactivation rates depend on not only relative humidity but also temperature, so that water content in air could determine the generation of reactive species such as hydroxyl radicals that are effective for the inactivation of B. atrophaeus spores.

  7. Investigation of capillary nanosecond discharges in air at moderate pressure: comparison of experiments and 2D numerical modelling

    NASA Astrophysics Data System (ADS)

    Klochko, Andrei V.; Starikovskaia, Svetlana M.; Xiong, Zhongmin; Kushner, Mark J.

    2014-09-01

    Nanosecond electrical discharges in the form of ionization waves are of interest for rapidly ionizing and exciting complex gas mixtures to initiate chemical reactions. Operating with a small discharge tube diameter can significantly increase the specific energy deposition and so enable optimization of the initiation process. Analysis of the uniformity of energy release in small diameter capillary tubes will aid in this optimization. In this paper, results for the experimentally derived characteristics of nanosecond capillary discharges in air at moderate pressure are presented and compared with results from a two-dimensional model. The quartz capillary tube, having inner and outer diameters of 1.5 and 3.4 mm, is about 80 mm long and filled with synthetic dry air at 27 mbar. The capillary tube with two electrodes at the ends is inserted into a break of the central wire of a long coaxial cable. A metal screen around the tube is connected to the cable ground shield. The discharge is driven by a 19 kV 35 ns voltage pulse applied to the powered electrode. The experimental measurements are conducted primarily by using a calibrated capacitive probe and back current shunts. The numerical modelling focuses on the fast ionization wave (FIW) and the plasma properties in the immediate afterglow after the conductive plasma channel has been established between the two electrodes. The FIW produces a highly focused region of electric field on the tube axis that sustains the ionization wave that eventually bridges the electrode gap. Results from the model predict FIW propagation speed and current rise time that agree with the experiment.

  8. Performance of Compressor of XJ-41-V Turbojet Engine. 3; Compressor Static-Pressure Rise at Equivalent Compressor Speeds of 5000, 7000, 8000, and 9000 rpm

    NASA Technical Reports Server (NTRS)

    Creagh, John W. R.; Ginsburg, Ambrose

    1947-01-01

    At the request of the Air Materiel Command, Army Air Forces, an investigation is being conducted at the NACA Cleveland laboratory to determine the performance characteristics of the XJ-41-V turbojet-engine compressor. The static-pressure variation in the direction of flow through the compressor was presented in reference 1 for an equivalent speed of 8000 rpm. An analysis of these pressure indicated that the maximum-flow limitation of the compressor was caused by separation, which reduced the effective flow area at the vaned-collector entrance. As a result of this analysis, the flow area at the vaned-collector entrance was increased to obtain larger mass flows. The area increase was obtained by cutting back the entrance edges of the collector vanes, which resulted in an increased vaneless-diffuser radius. Comparative performance of the original and revised compressors at an equivalent speed of 8000 rpm is presented. The static-pressure rise through the compressor, determined from static pressures at the impeller entrance and the vaned-collector exit, is also presented together with the compressor adiabatic efficiency and the mass flow over an equivalent speed range from 5000 to 9000 rpm. These static-pressure data are presented for the purpose of correlating the compressor performance with the turbojet-engine performance.

  9. Performance of Compressor of XJ-41-V Turbojet Engine VI - Analysis of Compressor Flow Choking. 6; Analysis of Compressor Flow Choking

    NASA Technical Reports Server (NTRS)

    Creagh, John W. R.; Ginsburg, Ambrose

    1948-01-01

    An extended analysis was made of the previously reported performance investigation of the original compressor from the XJ-41-v turbojet engine and a similar compressor revised a to obtain a 33-percent increase in the geometric passage area at the vaned-collector entrance. This analysis was based on the concept of the vaned-collector entrance as the throat section of a nozzle. Because of nonuniform air distribution at the vaned-collector entrance, approximately 90 percent of the available flow area was utilized in the original compressor and 94percent in the revised com$ressor. The increase in maximum weight flow obtained with the revised compressor was disproportionate to the increased effective critical throat area because. the air density at the revised vaned-collector entrance for maximum flow was lower than that obtained in the original compressor. This reduction in density resulted from the large pressure losses near the impeller inlet of the revised compressor, which is indicative of impending flow choking in the impeller, The.calculated maximum corrected weight-flow capacity of a compressor consisting of the revised vaneless diffuser and vaned collector with a theoretical impeller that combined peak impeller pressure ratio and peak impeller efficiency at the . maximum flow point would be 112 pounds per second for an equivalent impeller speed of 11,500 rpm;

  10. Two-Stage Energy Thermalization Mechanism in Nanosecond Pulse Discharges in Air and Hydrogen-Air Mixtures

    NASA Astrophysics Data System (ADS)

    Shkurenkov, Ivan; Lanier, Suzanne; Adamovich, Igor; Lempert, Walter

    2014-10-01

    Time-resolved and spatially resolved rotational temperature measurements in air and H2-air, by purely rotational Coherent Anti-Stokes Raman Spectroscopy (CARS), are presented. The experimental results demonstrate high accuracy of pure rotational psec CARS for thermometry measurements at low partial pressures of oxygen in nonequilibrium plasmas. The results are compared with modeling calculations using a state-specific master equation kinetic model of reacting hydrogen-air plasmas, showing good agreement. The results demonstrate that energy thermalization and temperature rise in these plasmas occur in two stages, (i) ``rapid'' heating, occurring on the time scale τrapid ~ 0 . 1 --1 μs .atm, caused by collisional quenching of excited electronic states of N2 molecules by O2, and (ii) ``slow'' heating, on the time scale τslow ~ 10 --100 μs .atm, caused primarily by N2 vibrational relaxation by O atoms (in air) and by chemical energy release during partial oxidation of hydrogen (in H2-air. Both energy thermalization mechanisms have major implications for plasma assisted combustion and plasma flow control.

  11. Development of high performance compressor discharge seal

    NASA Astrophysics Data System (ADS)

    Munson, John H.

    1992-07-01

    A gas lubricated film riding seal (FRFS) that is being developed for use in an advanced subsonic demonstrator engine is investigated. Results obtained indicate that, for gas turbine application, hydrodynamic FRFSs appear to be preferred to hydrostatic designs. A spiral groove design was the overall best seal, followed by a Rayleigh pad seal. Particular attention is given to the problem of integrating the seals into an engine in such a manner that distortion of the sealing faces is minimized. It is found that this can be accomplished in a straightforward manner.

  12. Investigation of an Experimental Supersonic Axial-Flow Compressor

    NASA Technical Reports Server (NTRS)

    Erwin, John R.; Wright, Linwood C.; Kantrowitz, Arthur

    1947-01-01

    An investigation is in progress at the Langley Laboratory of the NACA to explore the possibilities of axial-flow compressors operating with supersonic velocities relative to the blade rows. The first phase of this investigation, a study of supersonic diffusers, has been reported. The second phase, an analysis of supersonic compressors, has also been reported. Preliminary calculations have shown that very high pressure ratios across a stage, together with somewhat increased mass flows, are possible with compressors which decelerate air through the speed of sound in their rotor blading. These performance characteristics are desirable in compressors for aircraft jet propulsion units, gas turbines, or superchargers. The third phase, presented here, is a preliminary experimental investigation of a supersonic compressor designed to produce a high pressure ratio in a single stage.

  13. Surface treatment of polypropylene (PP) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Joshi, Ujjwal Man; Subedi, Deepak Prasad

    2015-07-01

    Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H2O), glycerol (C3H8O3) and diiodomethane (CH2I2) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase in surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

  14. Centrifugal compressor modifications and their effect on high-frequency pipe wall vibration

    SciTech Connect

    Motriuk, R.W.; Harvey, D.P.

    1998-08-01

    High-frequency pulsation generated by centrifugal compressors, with pressure wave-lengths much smaller than the attached pipe diameter, can cause fatigue failures of the compressor internals, impair compressor performance, and damage the attached compressor piping. There are numerous sources producing pulsation in centrifugal compressors. Some of them are discussed in literature at large (Japikse, 1995; Niese, 1976). NGTL has experienced extreme high-frequency discharge pulsation and pipe wall vibration on many of its radial inlet high-flow centrifugal gas compressor facilities. These pulsations led to several piping attachment failures and compressor internal component failures while the compressor operated within the design envelope. This paper considers several pulsation conditions at an NGTL compression facility which resulted in unacceptable piping vibration. Significant vibration attenuation was achieved by modifying the compressor (pulsation source) through removal of the diffuser vanes and partial removal of the inlet guide vanes (IGV). Direct comparison of the changes in vibration, pulsation, and performance are made for each of the modifications. The vibration problem, probable causes, options available to address the problem, and the results of implementation are reviewed. The effects of diffuser vane removal on discharge pipe wall vibration as well as changes in compressor performance are described.

  15. Efficient new process for the desulfurization of mixtures of air and hydrogen sulfide via a dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

    Dahle, S.

    2015-10-01

    The efficient removal of hydrogen sulfide, H2S, from streams of H2S in air via a dielectric barrier discharge (DBD) plasma has been investigated using a quadrupole mass spectrometer. A suitable plasma device with a reservoir for storing sorbent powder of various kinds within the plasma region was constructed. Plasma treatments of gas streams with high concentrations of hydrogen sulfide in air yielded a removal of more than 98% of the initial hydrogen sulfide and a deposition of sulfur at the surface of the dielectric, while small amounts of sulfur dioxide were generated. The presence of calcium carbonate within the plasma region of the DBD device resulted in the removal of over 99% of the initial hydrogen sulfide content and the removal of 98% of the initial sulfur dioxide impurities from the gas mixture.

  16. Compressor diaphragm assembly

    SciTech Connect

    Scalzo, A.

    1989-12-26

    This patent describes, in a combustion turbine having a casing, one or more slots of a first predetermined cross-section formed circumferentially within the casing at a compressor portion of the turbine, and a compressor diaphragm assembly adapted to be suspended from each of the one or more slots to provide a labyrinth seal with a plurality of compressor discs, a method of forming each compressor diaphragm assembly. It comprises: providing a plurality of vane airfoils each of which have an inner shroud formed integrally with the vane airfoil, and an outer portion attached to the vane airfoil; providing outer ring means for suspending each of the plurality of van airfoils at a stagger angle; suspending the plurality of vane airfoils from the outer ring means, thereby disposing each the vane airfoil and its respective outer portion at the stagger angle; and providing seal carrier means for engagement with each the inner shroud.

  17. A passive measurement of dissociated atom densities in atmospheric pressure air discharge plasmas using vacuum ultraviolet self-absorption spectroscopy

    SciTech Connect

    Laity, George; Fierro, Andrew; Dickens, James; Neuber, Andreas; Frank, Klaus

    2014-03-28

    We demonstrate a method for determining the dissociation degree of atmospheric pressure air discharges by measuring the self-absorption characteristics of vacuum ultraviolet radiation from O and N atoms in the plasma. The atom densities are determined by modeling the amount of radiation trapping present in the discharge, without the use of typical optical absorption diagnostic techniques which require external sources of probing radiation into the experiment. For an 8.0 mm spark discharge between needle electrodes at atmospheric pressure, typical peak O atom densities of 8.5 × 10{sup 17} cm{sup −3} and peak N atom densities of 9.9 × 10{sup 17} cm{sup −3} are observed within the first ∼1.0 mm of plasma near the anode tip by analyzing the OI and NI transitions in the 130.0–132.0 nm band of the vacuum ultraviolet spectrum.

  18. Kinetics of excited states and radicals in a nanosecond pulse discharge and afterglow in nitrogen and air

    NASA Astrophysics Data System (ADS)

    Shkurenkov, Ivan; Burnette, David; Lempert, Walter R.; Adamovich, Igor V.

    2014-12-01

    The present kinetic modelling calculation results provide key new insights into the kinetics of vibrational excitation of nitrogen and plasma chemical reactions in nanosecond pulse, ‘diffuse filament’ discharges in nitrogen and dry air at a moderate energy loading per molecule, ˜0.1 eV per molecule. It is shown that it is very important to take into account Coulomb collisions between electrons because they change the electron energy distribution function and, as a result, strongly affect populations of excited states and radical concentrations in the discharge. The results demonstrate that the apparent transient rise of N2 ‘first level’ vibrational temperature after the discharge pulse, as detected in the experiments, is due to the net downward V-V energy transfer in N2-N2 collisions, which increases the N2(X 1Σ, v = 1) population. Finally, a comparison of the model's predictions with the experimental data shows that NO formation in the afterglow occurs via reactive quenching of multiple excited electronic levels of nitrogen molecule, N2\\ast , by O atoms. ) published in this volume, which focuses on the kinetic modelling of the experiments. This paper presents the results of the experiments.

  19. Hermetically Sealed Compressor

    NASA Technical Reports Server (NTRS)

    Holtzapple, Mark T.

    1994-01-01

    Proposed hermetically sealed pump compresses fluid to pressure up to 4,000 atm (400 MPa). Pump employs linear electric motor instead of rotary motor to avoid need for leakage-prone rotary seals. In addition, linear-motor-powered pump would not require packings to seal its piston. Concept thus eliminates major cause of friction and wear. Pump is double-ended diaphragm-type compressor. All moving parts sealed within compressor housing.

  20. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field

    PubMed Central

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-01-01

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

  1. Experimental Study on Branch and Diffuse Type of Streamers in Leader Restrike of Long Air Gap Discharge

    NASA Astrophysics Data System (ADS)

    Chen, She; Zeng, Rong; Zhuang, Chijie; Zhou, Xuan; Ding, Yujian

    2016-03-01

    One of the main problems in the Ultra High Voltage (UHV) transmission project is to choose the external insulation distance, which requires a deep understanding of the long air gap discharge mechanism. The leader-streamer propagation is one of most important stages in long air gap discharge. In the conductor-tower lattice configuration, we have measured the voltage, the current on the high voltage side and the electric field in the gap. While the streamer in the leader-streamer system presented a conical or hyperboloid diffuse shape, the clear branch structure streamer in front of the leader was firstly observed by a high speed camera in the experiment. Besides, it is found that the leader velocity, width and injected charge for the branch type streamer are greater than those of a diffuse type. We propose that the phenomenon results from the high humidity, which was 15.5-16.5 g/m3 in our experiment. supported by the Fund of the National Priority Basic Research of China (2011CB209403) and National Natural Science Foundation of China (Nos. 51325703, 51377094, 51577098)

  2. Influence of air flow parameters on nanosecond repetitively pulsed discharges in a pin-annular electrode configuration

    NASA Astrophysics Data System (ADS)

    Heitz, Sylvain A.; Moeck, Jonas P.; Schuller, Thierry; Veynante, Denis; Lacoste, Deanna A.

    2016-04-01

    The effect of various air flow parameters on the plasma regimes of nanosecond repetitively pulsed (NRP) discharges is investigated at atmospheric pressure. The two electrodes are in a pin-annular configuration, transverse to the mean flow. The voltage pulses have amplitudes up to 15 kV, a duration of 10 ns and a repetition frequency ranging from 15 to 30 kHz. The NRP corona to NRP spark (C-S) regime transition and the NRP spark to NRP corona (S-C) regime transition are investigated for different steady and harmonically oscillating flows. First, the strong effect of a transverse flow on the C-S and S-C transitions, as reported in previous studies, is verified. Second, it is shown that the azimuthal flow imparted by a swirler does not affect the regime transition voltages. Finally, the influence of low frequency harmonic oscillations of the air flow, generated by a loudspeaker, is studied. A strong effect of frequency and amplitude of the incoming flow modulation on the NRP plasma regime is observed. Results are interpreted based on the cumulative effect of the NRP discharges and an analysis of the residence times of fluid particles in the inter-electrode region.

  3. Cooled spool piston compressor

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor)

    1993-01-01

    A hydraulically powered gas compressor receives low pressure gas and outputs a high pressure gas. The housing of the compressor defines a cylinder with a center chamber having a cross-sectional area less than the cross-sectional area of a left end chamber and a right end chamber, and a spool-type piston assembly is movable within the cylinder and includes a left end closure, a right end closure, and a center body that are in sealing engagement with the respective cylinder walls as the piston reciprocates. First and second annual compression chambers are provided between the piston enclosures and center housing portion of the compressor, thereby minimizing the spacing between the core gas and a cooled surface of the compressor. Restricted flow passageways are provided in the piston closure members and a path is provided in the central body of the piston assembly, such that hydraulic fluid flows through the piston assembly to cool the piston assembly during its operation. The compressor of the present invention may be easily adapted for a particular application, and is capable of generating high gas pressures while maintaining both the compressed gas and the compressor components within acceptable temperature limits.

  4. Electron emission mechanism during the nanosecond high-voltage pulsed discharge in pressurized air

    NASA Astrophysics Data System (ADS)

    Levko, D.; Yatom, S.; Vekselman, V.; Krasik, Ya. E.

    2012-02-01

    A comparison between the results of x-ray absorption spectroscopy of runaway electrons (RAEs) generated during nanosecond timescale high-voltage (HV) gas discharge and the simulated attenuation of the x-ray flux produced by the runaway electron spectrum calculated using particle-in-cell numerical modeling of such a type of discharge is presented. The particle-in-cell simulation considered the field and explosive emissions (EEs) of the electrons from the cathode. It is shown that the field emission is the dominant emission mechanism for the short-duration (<2.5 ns) high-voltage pulses, while for the long-duration (>5 ns) high-voltage pulses, the explosive emission is likely to play a significant role.

  5. Magnetic Ignition of Pulsed Gas Discharges in Air of Low Pressure in a Coaxial Plasma Gun

    NASA Technical Reports Server (NTRS)

    Thom, Karlheinz; Norwood, Joseph, Jr.

    1961-01-01

    The effect of an axial magnetic field on the breakdown voltage of a coaxial system of electrodes has been investigated by earlier workers. For low values of gas pressure times electrode spacing, the breakdown voltage is decreased by the application of the magnetic field. The electron cyclotron radius now assumes the role held by the mean free path in nonmagnetic discharges and the breakdown voltage becomes a function of the magnetic flux density. In this paper the dependence of the formative time lag as a function of the magnetic flux density is established and the feasibility of using a magnetic field for igniting high-voltage, high-current discharges is shown through theory and experiment. With a 36 microfarad capacitor bank charged to 48,000 volts, a peak current of 1.3 x 10( exp 6) amperes in a coaxial type of plasma gun was achieved with a current rise time of only 2 microseconds.

  6. Effect of electrode geometry on high energy spark discharges in air

    NASA Astrophysics Data System (ADS)

    Belmouss, Mounia

    The government, aerospace, and transportation industries are deeply invested in developing new technologies to improve the performance and maneuverability of current and future aircraft while reducing aerodynamic noise and environmental impact. One of the key pathways to meet these goals is through aerodynamic flow control, which can involve suppressing or inducing separation, transition and management of turbulence in boundary layers, increasing the lift and reducing the drag of airfoils, and gas mixing to control fluctuating forces and aerodynamic noise [1]. In this dissertation, the complex flow field following a spark discharge is studied for a range of geometries and discharge characteristics, and the possibilities for using the induced flow for aerodynamic control are assessed. This work shows the influence of the electrode configuration on the fluid dynamics following the spark discharge and how the hot gas evolution gives rise to various physical phenomena (i.e. generation of turbulence, inducing vorticity, and gas mixing) that can be used to modify the flow-field structure near the boundary layer on an aerodynamic surface.

  7. The effects of compressor seventh-stage bleed air extraction on performance of the F100-PW-220 afterburning turbofan engine

    NASA Technical Reports Server (NTRS)

    Evans, Alison B.

    1991-01-01

    A study was conducted to determine the effects of seventh-stage compressor bleed on the performance of the F100 afterburning turbofan engine. The effects of bleed on thrust, specific fuel consumption, fan turbine inlet temperature, bleed total pressure, and bleed total temperature were obtained from the engine manufacturer's status deck computer simulation. These effects were determined for power settings of intermediate, partial afterburning, and maximum afterburning for Mach numbers between 0.6 and 2.2 and for altitudes of 30,000, 40,000, and 50,000 ft. It was found that thrust loss and specific fuel consumption increase were approximately linear functions of bleed flow and, based on a percent-thrust change basis, were approximately independent of power setting.

  8. Performance Investigations of a Large Centrifugal Compressor from an Experimental Turbojet Engine

    NASA Technical Reports Server (NTRS)

    Ginsburg, Ambrose; Creagh, John W. R.; Ritter, William K.

    1948-01-01

    An investigation was conducted on a large centrifugal compressor from an experimental turbojet engine to determine the performance of the compressor and to obtain fundamental information on the aerodynamic problems associated with large centrifugal-type compressors. The results of the research conducted on the compressor indicated that the compressor would not meet the desired engine-design air-flow requirements (78 lb/sec) because of an air-flow restriction in the vaned collector (diffuser). Revision of the vaned collector resulted in an increased air-flow capacity over the speed range and showed improved matching of the impeller and diffuser components. At maximum flow, the original compressor utilized approximately 90 percent of the available geometric throat area at the vaned-collector inlet and the revised compressor utilized approximately 94 percent, regardless of impeller speed. The ratio of the maximum weight flows of the revised and original compressors were less than the ratio of effective critical throat areas of the two compressors because of the large pressure losses in the impeller near the impeller inelt and the difference increased with an increase in impeller speed. In order to further increase the pressure ratio and maximum weight flow of the compressor, the impeller must be modified to eliminate the pressure losses therein.

  9. Experimentally studying of axial compressor operation with steam

    NASA Astrophysics Data System (ADS)

    Batenin, V. M.; Zeigarnik, Yu. A.; Kosoi, A. S.; Datsenko, V. V.; Sinkevich, M. V.

    2015-12-01

    Steam offers numerous benefits when used as the working fluid in thermodynamic cycles. In lowtemperature cycles, where thermal energy is switched from one temperature potential to another (thermal transformers), steam is much less commonly used as a working fluid than in high-temperature cycles. The deficiencies of difficulties in using steam in thermal transformers include low pressure at the working temperatures and hence large specific volume. A compressor capable of high productivity having high discharge and relatively large increase in pressure is required. To that end, a multistage axial compressor from an airplane aircraft engine may be employed. To confirm the viability of this approach, the compressor of an AL-21 airplane aircraft engine is tested on a custom test bench. Experimental results are presented for a multistage axial compressor working with steam, when the input pressure is 0.5-5 kPa.

  10. Measurement of vibrationally excited N2(v) in an atmospheric-pressure air pulsed corona discharge using coherent anti-Stokes Raman scattering

    NASA Astrophysics Data System (ADS)

    Teramoto, Yoshiyuki; Ono, Ryo

    2014-08-01

    Vibrationally excited N2(v = 1, 2) in an atmospheric-pressure air pulsed corona discharge was measured using coherent anti-Stokes Raman scattering (CARS). In a dry air discharge, the vibrational temperature determined from the ratio N2(v = 2)/N2(v = 0), Tv2, was approximately 500 K higher than that determined from N2(v = 1)/N2(v = 0), Tv1, immediately after the discharge pulse. Both vibrational temperatures reached equilibrium within 100 μs after the discharge pulse by the vibration-to-vibration (V-V) process of N2-N2. The translational temperature was also measured using CARS. The rise in the translational temperature due to vibration-to-translation (V-T) energy transfer was not observed for a postdischarge time of 5 μs-1 ms in the dry-air discharge. However, when the air was humidified, a significant V-T energy transfer was observed. It was due to an extremely rapid V-T process of H2O-H2O following the V-V process of N2-H2O. Measurements showed that the humidification of the ambient air accelerated the decrease in the N2 vibrational temperature and increased the translational temperature. N2(v) was generated mostly in the secondary streamer, not in the primary one, according to estimation from the measured N2(v) density.

  11. Analysis of dynamic inlet distortion applied to a parallel compressor model

    NASA Technical Reports Server (NTRS)

    Wenzel, L. M.; Blaha, R. J.

    1977-01-01

    An investigation of surge was conducted by using a parallel compressor model of the J85-13 compressor implement on an analog computer. Surges were initiated by various types of dynamic disturbances in inlet pressure. The compressor model was less sensitive to disturbances of short duration, high frequency, and long duration where the compressor discharge pressure could react. Adding steady distortion to dynamic disturbances reduced the amount of dynamic disturbance required to effect surge. Steady and unsteady distortions combined linearly to reduce surge margin.

  12. Influence of an optical pulsed discharge on the structure of a supersonic air flow

    SciTech Connect

    Malov, A N; Orishich, A M

    2014-01-31

    We present the results of investigation of the parameters of an optical pulsed discharge (OPD) and their relation with gasdynamic parameters of a supersonic flow and with characteristics of laser radiation. For the first time the discrete objects are detected in the OPD by an optical method, namely, low-density caverns moving along with the flow. The propagation velocity of the thermal track arising in a supersonic flow under the action of the OPD is measured. It is found that at a pulse repetition rate of 90 – 120 kHz the caverns unite into a single plasma jet. (laser applications and other topics in quantum electronics)

  13. Compressor Calorimeter Test of R-410A Alternatives R-32, DR-5, and L-41a

    SciTech Connect

    Shrestha, Som S; Mahderekal, Isaac; Sharma, Vishaldeep; Abdelaziz, Omar

    2013-02-01

    As a contribution to the AHRI Low-GWP Alternative Refrigerants Evaluation Program (AREP), this study compares performance of alternative refrigerants R32, DR-5, and L-41A to that of refrigerant R-410A (baseline) in a scroll compressor designed for air-conditioning and heat pump applications. Compressor calorimeter tests were performed to evaluate the performance of the lower-GWP alternative refrigerants in place of the common refrigerant R-410A in a 36,000 Btu/hr compressor calorimeter using a compressor having a nominal rated capacity of 21,300 Btu/hr. Tests were conducted over a suction dew point temperature range of 10 F to 55 F in 5 F increments and a discharge dew point temperature range of 70 F to 140 F in 10 F increments. All the tests were performed with 20 F superheat, 40 F superheat and 65 F suction temperature. A liquid subcooling level of 15 F was maintained for all the test conditions. The tests showed that performance of these three lower-GWP alternative refrigerants is comparable to that of R-410A. For the 20 F superheat and 15 F subcooling test conditions, EERs of R32, DR-5, and L-41A were 90% to 99%, 96% to 99%, and 94% to 101%, respectively, compared to that of R-410A. Similarly, cooling capacities of R32, DR-5, and L-41A were 98% to 103%, 92% to 96%, and 84% to 92%, respectively, compared to that of R-410A.

  14. On spatial stabilization of dielectric barrier discharge microfilaments by residual heat build-up in air

    NASA Astrophysics Data System (ADS)

    Ráhel, Jozef; Szalay, Zsolt; Čech, Jan; Morávek, Tomás

    2016-04-01

    Microfilaments of dielectric barrier discharge are known for their multiple re-appearance at the same spot on dielectrics. This effect of localized re-appearance is driven by residual excited species and ions, surface charge deposited on the dielectric and the local temperature build-up resulting in the local increase of reduced electric field E/ΔN. To assess the magnitude of the latter, the breakdown voltage vs. temperature up to 180 °C was carefully measured at coplanar DBD and used as an input into the numerical simulation of heat build-up by the train of discharge pulses. An average reduction of breakdown voltage was found to be 20 V/K. The model predicted a quasi-stable microfilament temperature into which the thermal build-up rapidly converges. Its magnitude agreed well with the reported rotational temperature of similar electrode configuration. The impact of quasi-stable temperature on microfilament formation dynamics is further discussed. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.

  15. Spray droplet sizes with additives discharged from an air-assisted variable-rate nozzle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding droplet size distributions is essential to achieve constant spray quality for real-time variable-rate sprayers that synchronize spray outputs with canopy structures. Droplet sizes were measured for a custom-designed, air-assisted, five-port nozzle coupled with a pulse width modulated (...

  16. Small airblast fuel nozzle with high efficiency inner air swirler

    SciTech Connect

    Koblish, T.R.; Bell, L.D.

    1992-09-08

    This patent describes a gas turbine engine wherein upon cold ignition a stagnation air pressure of generally about 1 to about 1 [1/2] inches of water is supplied by the compressor to airblast fuel nozzles communicating with the combustor, means for introducing fuel into the chamber and air inlet passages space apart around the nozzle body upstream of the fuel discharge orifice and extending from the chamber to the exterior of the nozzle body for receiving air at the the stagnation air pressure, each air passage having converging sections canted relative to one another effective to provide an air pressure in the inner air swirl chamber of at least about 70% of the stagnation air pressure for enhancing inner air swirl strength for fuel atomization and cold ignition of the engine.

  17. Compressor map prediction tool

    NASA Astrophysics Data System (ADS)

    Ravi, Arjun; Sznajder, Lukasz; Bennett, Ian

    2015-08-01

    Shell Global Solutions uses an in-house developed system for remote condition monitoring of centrifugal compressors. It requires field process data collected during operation to calculate and assess the machine's performance. Performance is assessed by comparing live results of polytropic head and efficiency versus design compressor curves provided by the Manufacturer. Typically, these design curves are given for specific suction conditions. The further these conditions on site deviate from those prescribed at design, the less accurate the health assessment of the compressor becomes. To address this specified problem, a compressor map prediction tool is proposed. The original performance curves of polytropic head against volumetric flow for varying rotational speeds are used as an input to define a range of Mach numbers within which the non-dimensional invariant performance curve of head and volume flow coefficient is generated. The new performance curves of polytropic head vs. flow for desired set of inlet conditions are then back calculated using the invariant non-dimensional curve. Within the range of Mach numbers calculated from design data, the proposed methodology can predict polytropic head curves at a new set of inlet conditions within an estimated 3% accuracy. The presented methodology does not require knowledge of detailed impeller geometry such as throat areas, blade number, blade angles, thicknesses nor other aspects of the aerodynamic design - diffusion levels, flow angles, etc. The only required mechanical design feature is the first impeller tip diameter. Described method makes centrifugal compressor surveillance activities more accurate, enabling precise problem isolation affecting machine's performance.

  18. Asynchronous vibration problem of centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Fujikawa, T.; Ishiguro, N.; Ito, M.

    1980-01-01

    An unstable asynchronous vibration problem in a high pressure centrifugal compressor and the remedial actions against it are described. Asynchronous vibration of the compressor took place when the discharge pressure (Pd) was increased, after the rotor was already at full speed. The typical spectral data of the shaft vibration indicate that as the pressure Pd increases, pre-unstable vibration appears and becomes larger, and large unstable asynchronous vibration occurs suddenly (Pd = 5.49MPa). A computer program was used which calculated the logarithmic decrement and the damped natural frequency of the rotor bearing systems. The analysis of the log-decrement is concluded to be effective in preventing unstable vibration in both the design stage and remedial actions.

  19. Contribution of positive and negative ions to the electrohydrodynamic force in a dielectric barrier discharge plasma actuator operating in air

    SciTech Connect

    Boeuf, J. P.; Lagmich, Y.; Pitchford, L. C.

    2009-07-15

    We present a parametric study of the electrohydrodynamic force generated by surface dielectric barrier discharge plasma actuators in air for sinusoidal voltage waveforms. The simulation results confirm that momentum is transferred from the charged particles to the neutral species in the same direction during both positive and negative parts of the cycle. The momentum transfer is due to positive ions during the positive part of the cycle (electrode above the dielectric layer is the anode), and to negative ions during the negative part of the cycle. The relative contribution of the positive and negative parts of the cycle depends on the voltage amplitude and frequency. The model predicts that the contribution of negative ions tends to be dominant at low voltage frequencies and high voltage amplitudes.

  20. Ion energy and angular distributions onto polymer surfaces delivered by dielectric barrier discharge filaments in air: II. Particles

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia Yu; Kushner, Mark J.

    2011-06-01

    Atmospheric pressure streamers intersecting particles are of interest in the context of plasma aided combustion, where the particle may be a fuel aerosol droplet, or in sterilization of air, where the particle may be a bacterium. The ion energy and angular distributions (IEADs) incident on the particles, small curved dielectric surfaces, then in part determine the propensity for activating chemical reactions or, in the case of bacteria, the plasma's sterilization capability. In this paper, we discuss results from a computational investigation of IEADs on small particles (45 µm radius) produced by atmospheric pressure discharge. Streamers intersecting a particle momentarily generate a large sheath potential as the streamer passes by as the particle charges towards the plasma floating potential. During that time, ions of energies up to 3-10 eV can strike the particle. The permittivity of the particle and the streamer polarity in part determine the character of the IEAD.

  1. Dyeing mechanism and optimization of polyamide 6,6 functionalized with double barrier discharge (DBD) plasma in air

    NASA Astrophysics Data System (ADS)

    Oliveira, Fernando Ribeiro; Zille, Andrea; Souto, Antonio Pedro

    2014-02-01

    The physico-chemical improvements occasioned by DBD plasma discharge in dyeing process of polyamide 6,6 (PA66) fibers were investigated. The SEM, fluorescence microscopy, UV-vis spectroscopy, surface energy, FTIR, XPS and pH of aqueous extracts confirm the high polar functionalization of PA66 fibers due to plasma incorporation of oxygen atoms from atmospheric air. DBD plasma-generated reactive species preferentially break the CN bonds, and not the aliphatic C-C chain of PA66. Formation of low-molecular weight acidic molecules that act as dye "carrier" and creation of micro-channels onto PA66 surface seems to favor dye diffusion into the fiber cores. Plasma treatment allows high level of direct dye diffusion and fixation in PA66 fibers at lower temperatures and shorter dyeing times than traditional dyeing methods.

  2. Treatment of poly(ethylene terephthalate) foils by atmospheric pressure air dielectric barrier discharge and its influence on cell growth

    NASA Astrophysics Data System (ADS)

    Kuzminova, Anna; Vandrovcová, Marta; Shelemin, Artem; Kylián, Ondřej; Choukourov, Andrei; Hanuš, Jan; Bačáková, Lucie; Slavínská, Danka; Biederman, Hynek

    2015-12-01

    In this contribution an effect of dielectric barrier discharge (DBD) sustained in air at atmospheric pressure on surface properties of poly(ethylene terephthalate) (PET) foils is studied. It is found that exposure of PET to DBD plasma leads to rapid changes of surface chemical composition, wettability, surface morphology as well as mechanical properties of PET surface. In addition, based on biological tests that were performed using two cell types (Saos-2 human osteoblast-like cells and HUVEC human umbilical vein endothelial cells), it may be concluded that DBD plasma treatment positively influences cell growth on PET. This effect was found to be connected predominantly with increased surface energy and oxygen content of the surface of treated PET foils.

  3. Evaluation of circumferential airflow uniformity entering combustors from compressors. Volume 1: Discussion of data and results

    NASA Technical Reports Server (NTRS)

    Shadowen, J. H.; Egan, W. J., Jr.

    1972-01-01

    The compressor discharge airflow uniformity of two compressors from advanced engines, the J58 and F100/F401, was studied. Compressor discharge pressures and temperatures at up to 33 circumferential rake locations allowed the airflow distribution to be ascertained and computer plotted. Several flight conditions and compressor variables, i.e., inlet distortion, modified seals, etc., were analyzed. An unexpectedly high nonuniform airflow was found for both compressors. Circumferential airflow deviation differences of up to 52% from maximum to minimum were found for the J58, and up to 40% for the F100/F401. The effects of aerodynamic and thermal distortion were found to be additive. The data were analyzed for influence of exit guide vane wakes and found free of any effect. Data system errors were small in relation to the measured pressure and temperature variations.

  4. Modeling of experimental treatment of acetaldehyde-laden air and phenol-containing water using corona discharge technique.

    PubMed

    Faungnawakij, Kajornsak; Sano, Noriaki; Charinpanitkul, Tawatchai; Tanthapanichakoon, Wiwut

    2006-03-01

    Acetaldehyde-laden air and phenol-contaminated water were experimentally treated using corona discharge reactions and gas absorption in a single water-film column. Mathematical modeling of the combined treatment was developed in this work. Efficient removal of the gaseous acetaldehyde was achieved while the corona discharge reactions produced short-lived species such as O and O- as well as ozone. Direct contact of the radicals and ions with water was known to produce aqueous OH radical, which contributes to the decomposition of organic contaminants: phenol, absorbed acetaldehyde, and intermediate byproducts in the water. The influence of initial phenol concentration ranging from 15 to 50 mg L(-1) and that of influent acetaldehyde ranging from 0 to 200 ppm were experimentally investigated and used to build the math model. The maximum energetic efficiency of TOC, phenol, and acetaldehyde were obtained at 25.6 x 10(-9) mol carbon J(-1), 25.0 x 10(-9) mol phenol J(-1), and 2.0 x 10(-9) mol acetaldehyde J(-1), respectively. The predictions for the decomposition of acetaldehyde, phenol, and their intermediates were found to be in good agreement with the experimental results. PMID:16568779

  5. Numerical simulations of compact intracloud discharges as the Relativistic Runaway Electron Avalanche-Extensive Air Shower process

    NASA Astrophysics Data System (ADS)

    Arabshahi, S.; Dwyer, J. R.; Nag, A.; Rakov, V. A.; Rassoul, H. K.

    2014-01-01

    Compact intracloud discharges (CIDs) are sources of the powerful, often isolated radio pulses emitted by thunderstorms. The VLF-LF radio pulses are called narrow bipolar pulses (NBPs). It is still not clear how CIDs are produced, but two categories of theoretical models that have previously been considered are the Transmission Line (TL) model and the Relativistic Runaway Electron Avalanche-Extensive Air Showers (RREA-EAS) model. In this paper, we perform numerical calculations of RREA-EASs for various electric field configurations inside thunderstorms. The results of these calculations are compared to results from the other models and to the experimental data. Our analysis shows that different theoretical models predict different fundamental characteristics for CIDs. Therefore, many previously published properties of CIDs are highly model dependent. This is because of the fact that measurements of the radiation field usually provide information about the current moment of the source, and different physical models with different discharge currents could have the same current moment. We have also found that although the RREA-EAS model could explain the current moments of CIDs, the required electric fields in the thundercloud are rather large and may not be realistic. Furthermore, the production of NBPs from RREA-EAS requires very energetic primary cosmic ray particles, not observed in nature. If such ultrahigh-energy particles were responsible for NBPs, then they should be far less frequent than is actually observed.

  6. Influence of pulsed nanosecond volume discharge in atmospheric-pressure air on the electrical characteristics of MCT epitaxial films

    NASA Astrophysics Data System (ADS)

    Grigoryev, Denis V.; Voitsekhovskii, Alexandr V.; Lozovoy, Kirill A.; Nesmelov, Sergey N.; Dzyadukh, Stanislav M.; Tarasenko, Viktor F.; Shulepov, Michail A.; Dvoretskii, Sergei A.

    2015-12-01

    The purpose of this paper was investigating the effect of volume nanosecond discharge in air at atmospheric pressure on the electro-physical properties of the HgCdTe (MCT) epitaxial films grown by molecular beam epitaxy. Hall measurements of electro-physical parameters of MCT samples after irradiation have shown that there is a layer of epitaxial films exhibiting n-type conductivity that is formed in the near-surface area. After more than 600 pulses of influence parameters and thickness of the resulting n-layer is such that the measured field dependence of Hall coefficient corresponds to the material of n-type conductivity. Also it is shown that the impact of the discharge leads to significant changes in electro-physical characteristics of MIS structures. This fact is demonstrated by increase in density of positive fixed charge, change in the hysteresis type of the capacitance-voltage characteristic, an increase in density of surface states. The preliminary results show that it is possible to use such actions in the development of technologies of the controlled change in the properties of MCT.

  7. Compressor surge counter

    DOEpatents

    Castleberry, Kimberly N.

    1983-01-01

    A surge counter for a rotating compressor is provided which detects surging by monitoring the vibration signal from an accelerometer mounted on the shaft bearing of the compressor. The circuit detects a rapid increase in the amplitude envelope of the vibration signal, e.g., 4 dB or greater in less than one second, which is associated with a surge onset and increments a counter. The circuit is rendered non-responsive for a period of about 5 seconds following the detection which corresponds to the duration of the surge condition. This prevents multiple registration of counts during the surge period due to rapid swings in vibration amplitude during the period.

  8. Observation of X-rays from long laboratory negative discharge in STP air

    NASA Astrophysics Data System (ADS)

    Kochkin, Pavlo; van Deursen, A. P. J.; Ebert, Ute

    2014-05-01

    Pulses of x-rays emitted by lightning are one of the most intriguing among unsolved problem in physics of lightning. They have been detected from both - natural and rocket-triggered lightning. In natural lightning x-rays were detected during stepped leader process and later were associated with a single step. In triggered lighting x-rays were found to be originated from a tip of a dart leader that also possesses stepping propagation mechanism. Therefore, stepping mechanism is the key to understanding the x-ray pulses generated by lightning. Unfortunately, leader stepping mechanism itself is far from well understood. Negative long laboratory discharges also develop through a formation of a space stem/leader and they also generate bursts of x-ray radiation. In this study we investigate the development of a long negative laboratory spark in particular focusing on its x-ray emission. A 2 MV Marx generator delivers high-voltage standard lightning pulse with 1.2/50 microsec rise/fall time to a spark gap with conical electrodes. The distance between cone tips was varied between 1 m and 1.75 m. An upper voltage limit is set to about 1 MV level. The voltage is measured by capacitive high-voltage divider. Two Pearson 7427 current probes determine the currents through high-voltage and grounded electrodes. Two LaBr3 scintillator detectors were mounted in EMC-cabinets and recorded the x-rays. Picos4 Stanford Optics camera with intensified CCD is placed in 4 m distance from the spark gap and directed perpendicular to the spark plane. The camera allows us to make ns-fast images of pre-breakdown phenomena in controllable time. We discovered new details of space stem/leader formation and development in long laboratory sparks. The connection moment of positive part of the space stem/leader to negative high-voltage is accompanied by intense x-ray emission. Taking into account our previous study on positive discharge, we conclude that encounter between positive and negative streamers

  9. Spectrum of the Runaway Electron Beam Generated During a Nanosecond Discharge in Air at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.

    2016-04-01

    The spectrum of supershort avalanche runaway electron beam generated in air at atmospheric pressure is experimentally investigated using a time-of-flight spectrometer and attenuation curves. It is shown that the maximum of the electron energy distribution for the main (second) group of electrons is less than the energy eUm, where Um is the maximal voltage across the gap, and the difference between these energies depends on the design of the cathode and the interelectrode gap in a gas diode. It is confirmed that there are three groups of electrons with different energies in the runaway electron beam spectrum.

  10. Recent observations of lightning discharges from the top of a thundercloud into the clear air above

    NASA Astrophysics Data System (ADS)

    Vaughan, O. H.; Vonnegut, B.

    1989-09-01

    A note of inquiry published in a magazine read by airplane pilots has elicited 15 new observations of a rare form of lightning that comes out of the cloud top, goes up vertically, and terminates in the clear air above. These confirm previous observations showing that this phenomenon usually occurs above very large and energetic thunderclouds. However, small clouds with tops at 15,000 ft mean sea level (5000 m) have been observed to exhibit this rare form of lightning also. One of the more spectacular observations was made over the severe storm system that produced the devastating tornadoes of April 11, 1965.

  11. Recent observations of lightning discharges from the top of a thundercloud into the clear air above

    NASA Technical Reports Server (NTRS)

    Vaughan, O. H., Jr.; Vonnegut, B.

    1988-01-01

    A letter of inquiry to a magazine read by airplane pilots has elicited 15 new observations of a rare form of lightning that comes out of the cloud top, goes up vertically, and terminates in the clear air above. These confirm previous observations showing that this phenomenon usually occurs above very large and energetic thunderclouds. However, small clouds with tops at 15,000 feet have been observed to have this rare form of lightning also. One of the more spectacular observations was made over the severe storm that produced the devastating Xenia, Ohio, tornadoes of April 1965.

  12. Interaction of Streamer Discharges in Air and Other Oxygen-Nitrogen Mixtures

    SciTech Connect

    Luque, A.; Hundsdorfer, W.; Ebert, U.

    2008-08-15

    The interaction of streamers in nitrogen-oxygen mixtures such as air is studied. First, an efficient method for fully three-dimensional streamer simulations in multiprocessor machines is introduced. With its help, we find two competing mechanisms how two adjacent streamers can interact: through electrostatic repulsion and through attraction due to nonlocal photoionization. The nonintuitive effects of pressure and of the nitrogen-oxygen ratio are discussed. As photoionization is experimentally difficult to access, we finally suggest to measure it indirectly through streamer interactions.

  13. Surface treatment of polypropylene (PP) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    SciTech Connect

    Joshi, Ujjwal Man Subedi, Deepak Prasad

    2015-07-31

    Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H{sub 2}O), glycerol (C{sub 3}H{sub 8}O{sub 3}) and diiodomethane (CH{sub 2}I{sub 2}) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase in surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

  14. Plasma formation in atmospheric pressure helium discharges under different background air pressures

    SciTech Connect

    Liu Yaoge; Hao Yanpeng; Zheng Bin

    2012-09-15

    Atmospheric pressure glow discharges generated between parallel-plate electrodes in helium have been characterized using temporally resolved emission spectra. The variation of typical spectral lines over time has been analyzed. In helium with a low concentration of N{sub 2}, the emission of He at 706.5 nm is dominant and appears 500 ns earlier than N{sub 2}{sup +} first negative bands, indicating low reaction rates of Penning ionization and charge transfer in the initial stage. During the decay, it is the Penning ionization caused by He metastables with a long lifetime rather than the charge transfer reaction that leads to the long decay of N{sub 2}{sup +} emissions. When helium contains a higher concentration of N{sub 2} molecules, the N{sub 2}{sup +} first negative bands become the most intense, and emissions from He, N{sub 2}{sup +}, and O exhibit similar behavior as they increase. The emissions last for a shorter time under such conditions because of rapid consumption of He metastables and He{sub 2}{sup +}.

  15. Antenna Deployment for the Localization of Partial Discharges in Open-Air Substations.

    PubMed

    Robles, Guillermo; Fresno, José Manuel; Sánchez-Fernández, Matilde; Martínez-Tarifa, Juan Manuel

    2016-01-01

    Partial discharges are ionization processes inside or on the surface of dielectrics that can unveil insulation problems in electrical equipment. The charge accumulated is released under certain environmental and voltage conditions attacking the insulation both physically and chemically. The final consequence of a continuous occurrence of these events is the breakdown of the dielectric. The electron avalanche provokes a derivative of the electric field with respect to time, creating an electromagnetic impulse that can be detected with antennas. The localization of the source helps in the identification of the piece of equipment that has to be decommissioned. This can be done by deploying antennas and calculating the time difference of arrival (TDOA) of the electromagnetic pulses. However, small errors in this parameter can lead to great displacements of the calculated position of the source. Usually, four antennas are used to find the source but the array geometry has to be correctly deployed to have minimal errors in the localization. This paper demonstrates, by an analysis based on simulation and also experimentally, that the most common layouts are not always the best options and proposes a simple antenna layout to reduce the systematic error in the TDOA calculation due to the positions of the antennas in the array. PMID:27092501

  16. Antenna Deployment for the Localization of Partial Discharges in Open-Air Substations

    PubMed Central

    Robles, Guillermo; Fresno, José Manuel; Sánchez-Fernández, Matilde; Martínez-Tarifa, Juan Manuel

    2016-01-01

    Partial discharges are ionization processes inside or on the surface of dielectrics that can unveil insulation problems in electrical equipment. The charge accumulated is released under certain environmental and voltage conditions attacking the insulation both physically and chemically. The final consequence of a continuous occurrence of these events is the breakdown of the dielectric. The electron avalanche provokes a derivative of the electric field with respect to time, creating an electromagnetic impulse that can be detected with antennas. The localization of the source helps in the identification of the piece of equipment that has to be decommissioned. This can be done by deploying antennas and calculating the time difference of arrival (TDOA) of the electromagnetic pulses. However, small errors in this parameter can lead to great displacements of the calculated position of the source. Usually, four antennas are used to find the source but the array geometry has to be correctly deployed to have minimal errors in the localization. This paper demonstrates, by an analysis based on simulation and also experimentally, that the most common layouts are not always the best options and proposes a simple antenna layout to reduce the systematic error in the TDOA calculation due to the positions of the antennas in the array. PMID:27092501

  17. Nonpoint-pollution discharge permit testing and control strategies at Naval Air Station Whidbey Island. Master's thesis

    SciTech Connect

    Vogelsang, K.G.

    1991-01-01

    The purpose of this study was to analyze systematically a nonpoint storm water monitoring program at Naval Air Station Whidbey Island, Washington, to determine if more relevant data can be obtained at lower cost by revising the sampling location, frequency, or pollutants of interest. Current remedial investigations of contaminants in sediments, station hazardous material use information and station management plans provided the bulk of the data. Review of watersheds indicated that potential contamination by 26 compounds may be present in the storm runoff. Testing to identify the presence of these compounds is required to renew an existing National Pollution Discharge Elimination System permit for the air station. It was also found that the frequency of sampling could be reduced from 52 events per year to about 30 with no significant loss of statistical accuracy, thereby reducing the recurring cost of the sampling program. Also discussed are management practices and structural improvements that are technically feasible for controlling the two most significant pollutants, oil and grease and suspended solids. Best Management Practices are recommended to prevent or clean the spill of aviation fuel at the spill location. Use of synthetic oil-sorbent booms is recommended in lieu of the existing baffle treatment system.

  18. Parallel centrifugal gas compressors can be controlled more effectively

    SciTech Connect

    Staroselsky, N.; Ladin, L.

    1986-11-03

    Energy efficiency of parallel, centrifugal gas compressors can be improved by controlling the compressors to unload simultaneously to their surge limits. Simultaneous unloading to the surge limits can also allow more precise pressure control, provide better compressor protection, and allow simpler automated control systems. Specific power consumption is also offered as an improved definition of energy efficiency. Because polytropic efficiency, the most common efficiency measure, defines only the energy efficiency to compress a gas between the inlet port and the discharge port of a compressor, it does not account for the efficiency of gas delivery to the user. Specific power consumption includes energy costs that must be paid for but which are not accounted for by polytropic efficiency. This first of two articles discusses the concept of simultaneous loading and unloading of centrifugal compressors and compares the method with other control strategies. The concept of specific power consumption is also defined. The conclusion describes an algorithm for simultaneous loading and unloading to the surge limit. The efficiency and reliability of centrifugal compressors can be severely limited by the control system. Less-than-effective controls, rather than mechanical design, is often the cause of lost efficiency, shutdowns, and damage.

  19. Two-color interferometer for the study of laser filamentation triggered electric discharges in air

    SciTech Connect

    Point, Guillaume Brelet, Yohann; Arantchouk, Leonid; Carbonnel, Jérôme; Prade, Bernard; Mysyrowicz, André; Houard, Aurélien

    2014-12-15

    We present a space and time resolved interferometric plasma diagnostic for use on plasmas where neutral-bound electron contribution to the refractive index cannot be neglected. By recording simultaneously the plasma optical index at 532 and 1064 nm, we are able to extract independently the neutral and free electron density profiles. We report a phase resolution of 30 mrad, corresponding to a maximum resolution on the order of 4×10{sup 22} m{sup −3} for the electron density, and of 10{sup 24} m{sup −3} for the neutral density. The interferometer is demonstrated on centimeter-scale sparks triggered by laser filamentation in air with typical currents of a few tens of A.

  20. A helium regenerative compressor

    SciTech Connect

    Swift, W.L.; Nutt, W.E.; Sixsmith, H.

    1994-12-31

    This paper discusses the design and performance of a regenerative compressor that was developed primarily for use in cryogenic helium systems. The objectives for the development were to achieve acceptable efficiency in the machine using conventional motor and bearing technology while reducing the complexity of the system required to control contamination from the lubricants. A single stage compressor was built and tested. The compressor incorporates aerodynamically shaped blades on a 218 mm (8.6 inches) diameter impeller to achieve high efficiency. A gas-buffered non-contact shaft seal is used to oppose the diffusion of lubricant from the motor bearings into the cryogenic circuit. Since it is a rotating machine, the flow is continuous and steady, and the machine is very quiet. During performance testing with helium, the single stage machine has demonstrated a pressure ratio of 1.5 at a flow rate of 12 g/s with measured isothermal efficiencies in excess of 30%. This performance compares favorably with efficiencies generally achieved in oil flooded screw compressors.

  1. Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers

    NASA Astrophysics Data System (ADS)

    Huang, Jeng-Min; Luo, Kai-Wei; Chen, Ching-Fu; Chiang, Chung-Ping; Wu, Teng-Yuan; Chen, Chun-Han

    2013-03-01

    This study systematically investigates the slip phenomena in the centrifugal air compressor impellers by CFD. Eight impeller blades for different specific speeds, wrap angles and exit blade angles are designed by compressor design software to analyze their flow fields. Except for the above three variables, flow rate and number of blades are the other two. Results show that the deviation angle decreases as the flow rate increases. The specific speed is not an important parameter regarding deviation angle or slip factor for general centrifugal compressor impellers. The slip onset position is closely related to the position of the peak value in the blade loading factor distribution. When no recirculation flow is present at the shroud, the variations of slip factor under various flow rates are mainly determined by difference between maximum blade angle and exit blade angle, Δβmax-2. The solidity should be of little importance to slip factor correlations in centrifugal compressor impellers.

  2. Comprehensive evaluation of compressor oils by laboratory methods

    SciTech Connect

    Ershova, A.N.; Smertyak, Yu.L.; Lukashenko, E.V.; Kozhekin, A.V.; Bauman, V.N.

    1987-01-01

    The present work has been aimed at a comprehensive investigation of the carbon deposition, antioxidant, anticorrosion, and antiwear properties of a number of compressor oils, and at establishing a correlation between the results obtained in evaluations of high-temperature properties by different methods. The basic physicochemical properties and group compositions of the test oils are shown, which includes oils for reciprocating air compressors and other oils. Results are presented which were obtained in determinations of the carbon deposition tendency of compressor oils by two methods, the test-stand method and the laboratory method. Results are also shown from evaluations of the lubricity of the compressor oils and their anticorrosion properties at high temperature. The greatest viscosity increase is observed for the oil from medium-sulfur crudes with a high content of aromatic hydrocarbons, the smallest viscosity increase for oils with a naphthemic-paraffinic base.

  3. Resonant microwave pulse compressor operating in two frequencies

    NASA Astrophysics Data System (ADS)

    Beilin, L.; Shlapakovski, A.; Krasik, Ya. E.

    2013-07-01

    A resonant microwave pulse compressor with a hybrid (Magic) waveguide tee as an interference switch was studied in numerical simulations and experimentally. In this compressor, the necessary condition for energy storage in the compressor cavity is frequency-independent, so that its operation in different cavity eigenmodes without mechanical tuning is possible. An S-band compressor operating in two different frequencies (neighboring modes) was investigated. Two characteristic geometries corresponding to different regimes of the microwave energy accumulation and release were tested using input pulses of 200-400 kW power, 2.4 μs duration, and variable frequency, 2.8 to 2.9 GHz. The geometries are characterized by an RF electric field in the interference switch that is higher or lower than the field in the cavity. The plasma discharge that switches the phases of compressor operation from energy storage to release was initiated by small metallic cones placed in the appropriate location. For both geometries, the nanosecond output pulses in two resonant frequencies were obtained; the maximal peak output power measured was ˜1.8 MW. The efficiency of the microwave extraction was limited by either an insufficient coupling to the tee output arm (in the case of a high field in the tee) or non-uniformity of the plasma discharge (in the case of low field in the tee).

  4. Analyses of the Integration of Carbon Dioxide Removal Assembly, Compressor, Accumulator and Sabatier Carbon Dioxide Reduction Assembly

    NASA Technical Reports Server (NTRS)

    Jeng, Frank F.; Lafuse, Sharon; Smith, Frederick D.; Lu, Sao-Dung; Knox, James C.; Campbell, Mellssa L.; Scull, Timothy D.; Green Steve

    2010-01-01

    A tool has been developed by the Sabatier Team for analyzing/optimizing CO2 removal assembly, CO2 compressor size, its operation logic, water generation from Sabatier, utilization of CO2 from crew metabolic output, and Hz from oxygen generation assembly. Tests had been conducted using CDRA/Simulation compressor set-up at MSFC in 2003. Analysis of test data has validated CO2 desorption rate profile, CO2 compressor performance, CO2 recovery and CO2 vacuum vent in CDRA desorption. Optimizing the compressor size and compressor operation logic for an integrated closed air revitalization system Is being conducted by the Sabatier Team.

  5. A nanosecond surface dielectric barrier discharge in air at high pressures and different polarities of applied pulses: transition to filamentary mode

    NASA Astrophysics Data System (ADS)

    Stepanyan, S. A.; Starikovskiy, A. Yu; Popov, N. A.; Starikovskaia, S. M.

    2014-08-01

    The development of a nanosecond surface dielectric barrier discharge in air at pressures 1-6 bar is studied. At atmospheric pressure, the discharge develops as a set of streamers starting synchronously from the high-voltage electrode and propagating along the dielectric layer. Streamers cover the dielectric surface creating a ‘quasi-uniform’ plasma layer. At high pressures and high voltage amplitudes on the cathode, filamentation of the discharge is observed a few nanoseconds after the discharge starts. Parameters of the observed ‘streamers-to-filaments’ transition are measured; physics of transition is discussed on the basis of theoretical estimates and numerical modeling. Ionization-heating instability on the boundary of the cathode layer is suggested as a mechanism of filamentation.

  6. Estimation of Minimal Breakdown Point in a GaP Plasma Structure and Discharge Features in Air and Argon Media

    NASA Astrophysics Data System (ADS)

    Kurt, H. Hilal; Tanrıverdi, Evrim

    2016-08-01

    We present gas discharge phenomena in argon and air media using a gallium phosphide (GaP) semiconductor and metal electrodes. The system has a large-diameter ( D) semiconductor and a microscaled adjustable interelectrode gap ( d). Both theoretical and experimental findings are discussed for a direct-current (dc) electric field ( E) applied to this structure with parallel-plate geometry. As one of the main parameters, the pressure p takes an adjustable value from 0.26 kPa to 101 kPa. After collection of experimental data, a new theoretical formula is developed to estimate the minimal breakdown point of the system as a function of p and d. It is proven that the minimal breakdown point in the semiconductor and metal electrode system differs dramatically from that in metal and metal electrode systems. In addition, the surface charge density σ and spatial electron distribution n e are calculated theoretically. Current-voltage characteristics (CVCs) demonstrate that there exist certain negative differential resistance (NDR) regions for small interelectrode separations (i.e., d = 50 μm) and low and moderate pressures between 3.7 kPa and 13 kPa in Ar medium. From the difference of currents in CVCs, the bifurcation of the discharge current is clarified for an applied voltage U. Since the current differences in NDRs have various values from 1 μA to 7.24 μA for different pressures, the GaP semiconductor plasma structure can be used in microwave diode systems due to its clear NDR region.

  7. Improved operation of a microwave pulse compressor with a laser-triggered high-pressure gas plasma switch

    NASA Astrophysics Data System (ADS)

    Shlapakovski, A.; Gorev, S.; Krasik, Ya. E.

    2016-08-01

    The influence of laser beam parameters on the output pulses of a resonant microwave compressor with a laser-triggered plasma switch was investigated. The S-band compressor, consisting of a rectangular waveguide-based cavity and H-plane waveguide tee with a shorted side arm, was filled with pressurized dry air and pumped by 1.8-μs-long microwave pulses of up to 450 kW power. A Nd:YAG laser was used to ignite the gas discharge in the tee side arm for output pulse extraction. The laser beam (at 213 nm or 532 nm) was directed along the RF electric field lines. It was found that the compressor operated most effectively when the laser beam was focused at the center of the switch waveguide cross-section. In this case, the power extraction efficiency reached ˜47% at an output power of ˜14 MW, while when the laser beam was not focused the maximal extraction efficiency was only ˜20% at ˜6 MW output power. Focusing the laser beam resulted also in a dramatic decrease (down to <1 ns) in the delay of the output pulses' appearance with respect to the time of the beam's entrance into the switch, and the jitter of the output pulses' appearance was minimized. In addition, the quality of the output pulses' waveform was significantly improved.

  8. Experimental investigations of emission spectrum of a discharge with two liquid non-metallic (tap-water) electrodes in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Andre, P.; Barinov, Yu A.; Faure, G.; Shkol'nik, S. M.

    2011-09-01

    Experimental investigations of the emission spectrum in the wavelength range 240 nm <= λ <= 850 nm of a discharge burning in open air between two flows of tap water (a discharge with two liquid electrodes) with direct current supply are carried out. The axial and radial distributions of spectral characteristics at different currents i and discharge lengths L (i = 40-80 mA; L = 4-8 mm) are investigated. From spectral distributions of plasma emissivity, the obtained results show that the discharge radiates mainly in the ultraviolet region of the spectrum. The main contribution to the radiation power is made by N2, OH and NO molecules. The near-electrode regions radiate most intensively. A comparison of the previously published results of the investigations of such a discharge with the present results allows us to give qualitative explanations of the regularities in the axial distributions of spectral characteristics and their dependences on current and discharge length. An estimation of the dose of irradiation of the electrode liquid (tap water) by discharge radiation, having bactericidal effect (λ <= 310 nm) is made. The estimation shows that when water flows through the electrode attachment, the dose received by it is, by an order of magnitude, comparable to the dose which is necessary for sterilization.

  9. Design and experimental study of high-speed low-flow-rate centrifugal compressors

    SciTech Connect

    Gui, F.; Reinarts, T.R.; Scaringe, R.P.; Gottschlich, J.M.

    1995-12-31

    This paper describes a design and experimental effort to develop small centrifugal compressors for aircraft air cycle cooling systems and small vapor compression refrigeration systems (20--100 tons). Efficiency improvements at 25% are desired over current designs. Although centrifugal compressors possess excellent performance at high flow rates, low-flow-rate compressors do not have acceptable performance when designed using current approaches. The new compressors must be designed to operate at a high rotating speed to retain efficiency. The emergence of the magnetic bearing provides the possibility of developing such compressors that run at speeds several times higher than current dominating speeds. Several low-flow-rate centrifugal compressors, featured with three-dimensional blades, have been designed, manufactured and tested in this study. An experimental investigation of compressor flow characteristics and efficiency has been conducted to explore a theory for mini-centrifugal compressors. The effects of the overall impeller configuration, number of blades, and the rotational speed on compressor flow curve and efficiency have been studied. Efficiencies as high as 84% were obtained. The experimental results indicate that the current theory can still be used as a guide, but further development for the design of mini-centrifugal compressors is required.

  10. Investigation of X24C-2 10-Stage Axial-Flow Compressor. III - Surge Characteristics

    NASA Technical Reports Server (NTRS)

    Buckner, Howard A., Jr.; Downing, Richard M.

    1948-01-01

    Compressor operation at low air flows for a given speed is limited by unstable flow conditions, commonly called surge. An investigation of surge in centrifugal compressors (reference 1) showed that the pulsation of pressures and velocities occurred when the slope of the compressor characteristic curve was positive and that the magnitude and frequency, as well as the incidence of surge, depended on the capacity and resistance of the total system. Although the theory presented in reference 1 is applicable to axial-floe compressors, little experimental information is available on the surge characteristics of the individual stages of axial-flow compressors, or on the variation of the surge characteristics with operating conditions. During the investigation to determine the performance of the X24C-2 compressor (references 2 and 3), instrumentation was added to study the surge characteristics and to determine the effect of speed and inlet pressure on the frequency, amplitude, and phase relation of the pressure pulsations behind each stage.

  11. The influence of the sand-dust environment on air-gap breakdown discharge characteristics of the plate-to-plate electrode

    NASA Astrophysics Data System (ADS)

    He, Bo; Zhang, Gang; Chen, Bangfa; Gao, Naikui; Li, Yaozhong; Peng, Zongren; Jin, Haiyun

    2010-03-01

    The experiments of plane-plane gap discharge was carried out in an environment of artificial sandstorm. By comparing and analyzing the differences in gap breakdown voltage between the sand & dust environment and clean air, some problems were investigated, such as effects of wind speed and particle concentration on the breakdown voltage, differences of gap discharge characteristics between the dust & sand medium and the clean air medium. The results showed that compared with the clean air environment, the dust & sand environment had a decreased gap breakdown voltage. The longer the gap distance, the greater the voltage drop; the breakdown voltage decreased with the increase of particle concentration in flow. With the increase of wind speed, the breakdown voltage decreased at the beginning and rose afterwards. The results of the paper may helpful for further research regarding the unidentified flashover and external insulation characteristics of the HV power grid in the dust & sand environment.

  12. Rotating flux compressor for energy conversion

    SciTech Connect

    Chowdhuri, P.; Linton, T.W.; Phillips, J.A.

    1983-01-01

    The rotating flux compressor (RFC) converts rotational kinetic energy into an electrical output pulse which would have higher energy than the electrical energy initially stored in the compressor. An RFC has been designed in which wedge-shaped rotor blades pass through the air gaps between successive turns of a solenoid, the stator. Magnetic flux is generated by pulsing the stator solenoids when the inductance is a maximum, i.e., when the flux fills the stator-solenoid volume. Connecting the solenoid across a load conserves the flux which is compressed within the small volume surrounding the stator periphery when the rotor blades cut into the free space between the stator plates, creating a minimum-inductance condition. The unique features of this design are: (1) no electrical connections (brushes) to the rotor; (2) no conventional windings; and (3) no maintenance. The device has been tested up to 5000 rpm of rotor speed.

  13. New technology enhances compressor performance

    SciTech Connect

    Not Available

    1992-03-01

    This paper reports on new technology using active magnetic bearings and dry gas seals for oil-free compressors, a modified crankshaft arrangement for high-pressure centrifugal compressors, and a grid valve for steam turbines which enhances compressor reliability and longevity. Thermodyn, a division of Framatome, reports it has incorporated this new compressor technology in high-performance facilities equipped with advanced computers to improve its compressor and turbine design and manufacturing. Powerful computer programs associated with CAD were used for accurate geometric design of complex-shape parts which were then produced on N-C machine tools. These precise geometric designs have benefited centrifugal compressors with high or low volume flow, high molecular weight or high flow pressure.

  14. An in situ and downstream study of non-thermal plasma chemistry in an air fed dielectric barrier discharge (DBD)

    NASA Astrophysics Data System (ADS)

    Al-Abduly, Abdullah; Christensen, Paul

    2015-12-01

    This paper reports a spectroscopic study of non-thermal plasma chemistry in an air-fed dielectric barrier discharge (DBD) plasma jet. In situ analysis (i.e. the analysis of the plasma glow) and downstream analysis were carried out to identify and monitor species produced in the plasma as they propagate from the plasma glow to downstream regions. The analyses were carried out using Fourier Transform InfraRed (FTIR) and UV-Vis spectroscopies. The species: O3, N2O5, N2O, HNO3, CO2, CO and, for the first time, a vibrationally excited form of CO2 (i.e. \\text{CO}2* (v)) were identified in the plasma glow, while O3, N2O5, HNO3 and N2O were detected in the downstream exhaust. The behaviour of these species was monitored as a function of a range of experimental conditions including: input power, gas flow rate, relative humidity, gas temperature and feed gas composition. In addition, the uncertainty associated with UV-vis detection of ozone in the presence of N2O5 and/or HNO3 as interfering species was determined.

  15. Social perceptions about community life with people with mental illness: study of a discharge program in Buenos Aires province, Argentina.

    PubMed

    Ardila-Gómez, Sara; Ares-Lavalle, Guadalupe; Fernández, Marina; Hartfiel, María Isabel; Borelli, Mariana; Canales, Valeria; Stolkiner, Alicia

    2015-01-01

    Effects of living near people with mental illness in community settings have been researched as part of psychiatric reform evaluation. However, these studies have been carried out mostly in industrialized countries, where social contexts differ from those in which psychiatric reform is now being implemented. To analyze the effects of community life with people with mental illness in the neighborhoods in which they live, in Buenos Aires, Argentina. A questionnaire was administered to randomly-selected neighbors of group homes of a discharge program and an equivalent control area (n = 236). Data was analyzed both quantitatively and qualitatively. Significant differences were found between being a neighbor and having a high degree of acceptance toward people with mental illness. In addition, significant associations were found between neighbors having a high-perceived social cohesion and having a high level of acceptance toward the mentally ill. Living near people with mental illness is associated with better acceptance toward them; these results are congruent with those results found in other cultural contexts. PMID:24965092

  16. Functionalization of Hydrogen-free Diamond-like Carbon Films using Open-air Dielectric Barrier Discharge Atmospheric Plasma Treatments

    SciTech Connect

    Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Instituto de Materiales de Madrid, C.S.I.C., Cantoblanco, 28049 Madrid, Spain; Instituto de Quimica-Fisica"Rocasolano"C.S.I.C., 28006 Madrid, Spain; Mahasarakham University, Mahasarakham 44150, Thailand; CASTI, CNR-INFM Regional Laboratory, L'Aquila 67100, Italy; SUNY Upstate Medical University, Syracuse, NY 13210, USA; Endrino, Jose; Endrino, J. L.; Marco, J. F.; Poolcharuansin, P.; Phani, A.R.; Allen, M.; Albella, J. M.; Anders, A.

    2007-12-28

    A dielectric barrier discharge (DBD) technique has been employed to produce uniform atmospheric plasmas of He and N2 gas mixtures in open air in order to functionalize the surface of filtered-arc deposited hydrogen-free diamond-like carbon (DLC) films. XPS measurements were carried out on both untreated and He/N2 DBD plasma treated DLC surfaces. Chemical states of the C 1s and N 1s peaks were collected and used to characterize the surface bonds. Contact angle measurements were also used to record the short- and long-term variations in wettability of treated and untreated DLC. In addition, cell viability tests were performed to determine the influence of various He/N2 atmospheric plasma treatments on the attachment of osteoblast MC3T3 cells. Current evidence shows the feasibility of atmospheric plasmas in producing long-lasting variations in the surface bonding and surface energy of hydrogen-free DLC and consequently the potential for this technique in the functionalization of DLC coated devices.

  17. Communication: The influence of CO2 poisoning on overvoltages and discharge capacity in non-aqueous Li-Air batteries

    NASA Astrophysics Data System (ADS)

    Mekonnen, Yedilfana S.; Knudsen, Kristian B.; Mýrdal, Jon S. G.; Younesi, Reza; Højberg, Jonathan; Hjelm, Johan; Norby, Poul; Vegge, Tejs

    2014-03-01

    The effects of Li2CO3 like species originating from reactions between CO2 and Li2O2 at the cathode of non-aqueous Li-air batteries were studied by density functional theory (DFT) and galvanostatic charge-discharge measurements. Adsorption energies of CO2 at various nucleation sites on a stepped ({1bar 100}) Li2O2 surface were determined and even a low concentration of CO2 effectively blocks the step nucleation site and alters the Li2O2 shape due to Li2CO3 formation. Nudged elastic band calculations show that once CO2 is adsorbed on a step valley site, it is effectively unable to diffuse and impacts the Li2O2 growth mechanism, capacity, and overvoltages. The charging processes are strongly influenced by CO2 contamination, and exhibit increased overvoltages and increased capacity, as a result of poisoning of nucleation sites: this effect is predicted from DFT calculations and observed experimentally already at 1% CO2. Large capacity losses and overvoltages are seen at higher CO2 concentrations.

  18. Light intensity compressor

    DOEpatents

    Rushford, Michael C.

    1990-01-01

    In a system for recording images having vastly differing light intensities over the face of the image, a light intensity compressor is provided that utilizes the properties of twisted nematic liquid crystals to compress the image intensity. A photoconductor or photodiode material that is responsive to the wavelength of radiation being recorded is placed adjacent a layer of twisted nematic liquid crystal material. An electric potential applied to a pair of electrodes that are disposed outside of the liquid crystal/photoconductor arrangement to provide an electric field in the vicinity of the liquid crystal material. The electrodes are substantially transparent to the form of radiation being recorded. A pair of crossed polarizers are provided on opposite sides of the liquid crystal. The front polarizer linearly polarizes the light, while the back polarizer cooperates with the front polarizer and the liquid crystal material to compress the intensity of a viewed scene. Light incident upon the intensity compressor activates the photoconductor in proportion to the intensity of the light, thereby varying the field applied to the liquid crystal. The increased field causes the liquid crystal to have less of a twisting effect on the incident linearly polarized light, which will cause an increased percentage of the light to be absorbed by the back polarizer. The intensity of an image may be compressed by forming an image on the light intensity compressor.

  19. Light intensity compressor

    DOEpatents

    Rushford, Michael C.

    1990-02-06

    In a system for recording images having vastly differing light intensities over the face of the image, a light intensity compressor is provided that utilizes the properties of twisted nematic liquid crystals to compress the image intensity. A photoconductor or photodiode material that is responsive to the wavelength of radiation being recorded is placed adjacent a layer of twisted nematic liquid crystal material. An electric potential applied to a pair of electrodes that are disposed outside of the liquid crystal/photoconductor arrangement to provide an electric field in the vicinity of the liquid crystal material. The electrodes are substantially transparent to the form of radiation being recorded. A pair of crossed polarizers are provided on opposite sides of the liquid crystal. The front polarizer linearly polarizes the light, while the back polarizer cooperates with the front polarizer and the liquid crystal material to compress the intensity of a viewed scene. Light incident upon the intensity compressor activates the photoconductor in proportion to the intensity of the light, thereby varying the field applied to the liquid crystal. The increased field causes the liquid crystal to have less of a twisting effect on the incident linearly polarized light, which will cause an increased percentage of the light to be absorbed by the back polarizer. The intensity of an image may be compressed by forming an image on the light intensity compressor.

  20. What matters most: Are summer stream temperatures more sensitive to changing air temperature, changing discharge, or changing riparian vegetation under future climates?

    NASA Astrophysics Data System (ADS)

    Diabat, M.; Haggerty, R.; Wondzell, S. M.

    2012-12-01

    We investigated stream temperature responses to changes in both air temperature and stream discharge projected for 2040-2060 from downscaled GCMs and changes in the height and canopy density of streamside vegetation. We used Heat Source© calibrated for a 37 km section of the Middle Fork John Day River located in Oregon, USA. The analysis used the multiple-variable-at-a-time (MVAT) approach to simulate various combinations of changes: 3 levels of air warming, 5 levels of stream flow (higher and lower discharges), and 6 types of streamside vegetation. Preliminary results show that, under current discharge and riparian vegetation conditions, projected 2 to 4 °C increase in air temperature will increase the 7-day Average Daily Maximum Temperature (7dADM) by 1 to 2 °C. Changing stream discharge by ±30% changes stream temperature by ±0.5 °C, and the influence of changing discharge is greatest when the stream is poorly shaded. In contrast, the 7dADM could change by as much as 11°C with changes in riparian vegetation from unshaded conditions to heavily shaded conditions along the study section. The most heavily shaded simulations used uniformly dense riparian vegetation over the full 37-km reach, and this vegetation was composed of the tallest trees and densest canopies that can currently occur within the study reach. While this simulation represents an extreme case, it does suggest that managing riparian vegetation to substantially increase stream shade could decrease 7dADM temperatures relative to current temperatures, even under future climates when mean air temperatures have increased from 2 to 4 °C.

  1. Changes in the electro-physical properties of MCT epitaxial films affected by a plasma volume discharge induced by an avalanche beam in atmospheric-pressure air

    NASA Astrophysics Data System (ADS)

    Grigoryev, D. V.; Voitsekhovskii, A. V.; Lozovoy, K. A.; Tarasenko, V. F.; Shulepov, M. A.

    2015-11-01

    In this paper the influence of the plasma volume discharge of nanosecond duration formed in a non-uniform electric field at atmospheric pressure on samples of epitaxial films HgCdTe (MCT) films are discussed. The experimental data show that the action of pulses of nanosecond volume discharge in air at atmospheric pressure leads to changes in the electrophysical properties of MCT epitaxial films due to formation of a near-surface high- conductivity layer of the n-type conduction. The preliminary results show that it is possible to use such actions in the development of technologies for the controlled change of the properties of MCT.

  2. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  3. Discharge/charge characteristic of Li-air cells using carbon-supported LaMn0.6Fe0.4O3 as an electrocatalyst

    NASA Astrophysics Data System (ADS)

    Yuasa, Masayoshi; Matsuyoshi, Tsubasa; Kida, Tetsuya; Shimanoe, Kengo

    2013-11-01

    The discharge/charge performance of Li-air cell using the carbon-supported LaMn0.6Fe0.4O3 nanoparticle as a cathode catalyst was investigated in this study. The carbon-supported LaMn0.6Fe0.4O3 nanoparticle was prepared via a reverse homogeneous precipitation method, and fabricated to air electrode. Li-air cell was constructed using air electrode, Li metal foil and 1.0 M LiPF6 in propylene carbonate as a cathode, anode and electrolyte, respectively. As the result, the carbon-supported LaMn0.6Fe0.4O3 nanoparticle exhibited both the oxygen evolution activity and the oxygen reduction activity in the non-aqueous electrolyte. The investigation about the presence and absence of the catalytic layer and the gas diffusion layer revealed that each layer is indispensable for the excellent electrode performance, and that the catalytic layer and the gas diffusion layer has a important role to supply the electrolyte and the oxygen gas, respectively. The investigation about the amount of the catalytic layer and the effect of the oxygen concentration revealed that the oxygen diffusability into the air electrode strongly affects to the discharge capacity of Li-air cells.

  4. Preliminary performance of the Brayton 4.25 inch radial compressor operating in a helium xenon gas mixture

    NASA Technical Reports Server (NTRS)

    Asadourian, A. S.; Hecker, T. P.; Kruchowy, R.

    1971-01-01

    Compressor performance was mapped during the Brayton cycle power system testing. The range of testing included three shaft speeds: the design speed of 36,000 rpm, 10 percent overspeed (39,600 rpm), and 10 percent underspeed (32,400 rpm). A range of compressor inlet temperatures from 60 F to 120 F and discharge pressures from 20 to 45 psia were included. The effects of turbine inlet temperatures (from 1200 F to 1600 F) on the compressor were also studied. The data presented include plots of weight flow, compressor pressure ratio, efficiency, and temperature-rise ratio.

  5. Compressed air energy storage system

    SciTech Connect

    Ahrens, F.W.; Kartsounes, G.T.

    1981-07-28

    An internal combustion reciprocating engine is operable as a compressor during slack demand periods utilizing excess power from a power grid to charge air into an air storage reservoir and as an expander during peak demand periods to feed power into the power grid utilizing air obtained from the air storage reservoir together with combustible fuel. Preferably the internal combustion reciprocating engine is operated at high pressure and a low pressure turbine and compressor are also employed for air compression and power generation.

  6. Compressed air energy storage system

    DOEpatents

    Ahrens, Frederick W.; Kartsounes, George T.

    1981-01-01

    An internal combustion reciprocating engine is operable as a compressor during slack demand periods utilizing excess power from a power grid to charge air into an air storage reservoir and as an expander during peak demand periods to feed power into the power grid utilizing air obtained from the air storage reservoir together with combustible fuel. Preferably the internal combustion reciprocating engine is operated at high pressure and a low pressure turbine and compressor are also employed for air compression and power generation.

  7. Compressed air energy storage system

    DOEpatents

    Ahrens, F.W.; Kartsounes, G.T.

    An internal combustion reciprocating engine is operable as a compressor during slack demand periods utilizing excess power from a power grid to charge air into an air storage reservoir and as an expander during peak demand periods to feed power into the power grid utilizing air obtained from the air storage reservoir together with combustion reciprocating engine is operated at high pressure and a low pressure turbine and compressor are also employed for air compression and power generation.

  8. Pressure oscillations occurring in a centrifugal compressor system with and without passive and active surge control

    SciTech Connect

    Jungowski, W.M.; Weiss, M.H.; Price, G.R.

    1996-01-01

    A study of pressure oscillations occurring in small centrifugal compressor systems without a plenum is presented. Active and passive surge control were investigated theoretically and experimentally for systems with various inlet and discharge piping configurations. The determination of static and dynamic stability criteria was based on Greitzer`s (1981) lumped parameter model modified to accommodate capacitance of the piping. Experimentally, passive control using globe valves closely coupled to the compressor prevented the occurrence of surge even with the flow reduced to zero. Active control with a sleeve valve located at the compressor was effective but involved a significant component of passive throttling which reduced the compressor efficiency. With an oscillator connected to a short side branch at the compressor, effective active control was achieved without throttling. Both methods of active control reduced the flow rate at surge onset by about 30%. In general, the experiments qualitatively confirmed the derived stability criteria.

  9. Formulation of a distortion index based on peak compressor pressure ratios

    NASA Technical Reports Server (NTRS)

    Calogeras, J. E.; Burstadt, P. L.

    1974-01-01

    In order to effectively use a compressor face total-pressure distortion index as a measure of inlet-engine compatibility, a correlation of distortion amplitude with stall margin must be developed with minimal scatter. A recent analysis of data recorded in extensive distortion screen tests with the J85-GE-13 turbojet engine has resulted in a correlation based on compressor discharge pressure ratioed to the minimum pressure at the compressor face. Simply by determining compressor stall lines with a single hub radial distortion pattern, a single tip radial pattern, and with undistorted inflow, the overall compressor pressure ratio at stall for even the most complex distortion pattern was found to be predictable.

  10. Unsteady behavior and control of vortices in centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Ohta, Yutaka; Fujisawa, Nobumichi

    2014-10-01

    Two examples of the use of vortex control to reduce noise and enhance the stable operating range of a centrifugal compressor are presented in this paper. In the case of high-flow operation of a centrifugal compressor with a vaned diffuser, a discrete frequency noise induced by interaction between the impeller-discharge flow and the diffuser vane, which appears most notably in the power spectra of the radiated noise, can be reduced using a tapered diffuser vane (TDV) without affecting the performance of the compressor. Twin longitudinal vortices produced by leakage flow passing through the tapered portion of the diffuser vane induce secondary flow in the direction of the blade surface and prevent flow separation from the leading edge of the diffuser. The use of a TDV can effectively reduce both the discrete frequency noise generated by the interaction between the impeller-discharge flow and the diffuser surface and the broadband turbulent noise component. In the case of low-flow operation, a leading-edge vortex (LEV) that forms on the shroud side of the suction surface near the leading edge of the diffuser increases significantly in size and blocks flow in the diffuser passage. The formation of an LEV may adversely affect the performance of the compressor and may cause the diffuser to stall. Using a one-side tapered diffuser vane to suppress the evolution of an LEV, the stable operating range of the compressor can be increased by more than 12 percent, and the pressure-rise characteristics of the compressor can be improved. The results of a supplementary examination of the structure and unsteady behavior of LEVs, conducted by means of detailed numerical simulations, are also presented.

  11. VIEW OF COMPRESSOR ROOM AT GROUND LEVEL SHOWING COMPRESSOR EQUIPMENT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF COMPRESSOR ROOM AT GROUND LEVEL SHOWING COMPRESSOR EQUIPMENT. VIEW FACING SOUTH - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

  12. General view of low pressure compressor (unit #3) with compressor ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of low pressure compressor (unit #3) with compressor in foreground and engines in background. High pressure stage is on left, low pressure stage is on right. - Burnsville Natural Gas Pumping Station, Saratoga Avenue between Little Kanawha River & C&O Railroad line, Burnsville, Braxton County, WV

  13. Neutral gas temperature maps of the pin-to-plate argon micro discharge into the ambient air

    SciTech Connect

    Xu, S. F.; Zhong, X. X.; Majeed, Asif

    2015-03-15

    This study is designed to explore the two dimensional temperature maps of the atmospheric argon discharge consisting of pin-to-plane electrodes supplied by a high voltage DC source. After checking the stability of the micro discharge, the two dimensional image plane focused by a quartz lens was scanned by the fiber probe driven by a 3D Mobile Platform. The rotational and vibrational temperatures are calculated using nitrogen emissions collected by the high resolution spectrometer and high sensitive intensified charge coupled device. The rotational temperature varies from 1558.15 K to 2621.14 K and vibrational temperature varies from 3010.38 K to 3774.69 K, indicating a great temperature gradient due to small discharge size. The temperature maps show a lateral expansion and a sharp truncation in the radial direction. A double layers discharge is identified, where an arc discharge coats the glow discharge.

  14. Miniature Piezoelectric Compressor for Joule-Thomson Cryocoolers

    NASA Astrophysics Data System (ADS)

    Sobol, Sergey; Tzabar, Nir; Grossman, Gershon

    Joule-Thomson (JT) cryocoolers operate with a continuous flow of the working fluid that enters the cooler at a high pressure and leaves it at a lower pressure. Ideally, the temperature of the outgoing fluid equals the temperature of the entering fluid. JT cryocoolers that operate with pure refrigerants require high pressure of a few tens of MPa where the low pressure is usually around 0.1 MPa. Circulation of the working fluid in such cases requires high pressure ratio compressors that evidently have large dimensions. JT cryocoolers can operate with much lower pressure ratios by using mixed-refrigerants. Cooling from 300 K to about 80 K in a single stage cryocooler normally requires a pressure ratio of about 1:25. In the present research a miniature compressor driven by piezoelectric elements is developed in collaboration between Rafael and the Technion. This type of compressor has the advantage of improved long life compared to other mechanical compressors, very low vibrations, and silent operation. In the current case, the design goal of the intake and discharge pressures has been 0.1 and 2.5 MPa, respectively, with a flow rate of 0.06 g/s. The compressor has two compression stages; 1:5 and 5:25. Several configurations have been considered, fabricated, and tested. The performance of the last configuration approaches the desired specification and is presented in the current paper together with the design concept.

  15. Modelling radiation spectrum of a discharge with two liquid non-metallic (tap-water) electrodes in air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Andre, P.; Barinov, Yu A.; Faure, G.; Shkol'nik, S. M.

    2011-09-01

    The emission spectra of a column of a direct-current discharge in open air which is performed between two tap-water electrodes (two tap-water flows) are studied in the 240-450 nm spectral range. A comparison of the values of spectral emissivities is made between experimental spectra and the calculated spectra. The emission spectrum calculation is made for four molecules, N2, O2, NO and OH that are present in air plasma. The first part of this paper focuses on building the spectra calculation; the required data are detailed. In the second part, rotational, vibrational and excitational temperatures are determined with the Boltzmann distribution assumed on the quantum states. For that purpose, a comparison of the modelled spectra and the experimental spectra is made in the different parts of the discharge column.

  16. Low GWP Refrigerants Modelling Study for a Room Air Conditioner Having Microchannel Heat Exchangers

    SciTech Connect

    Shen, Bo; Bhandari, Mahabir S

    2016-01-01

    Microchannel heat exchangers (MHX) have found great successes in residential and commercial air conditioning applications, being compact heat exchangers, to reduce refrigerant charge and material cost. This investigation aims to extend the application of MHXs in split, room air conditioners (RAC), per fundamental heat exchanger and system modelling. For this paper, microchannel condenser and evaporator models were developed, using a segment-to-segment modelling approach. The microchannel heat exchanger models were integrated to a system design model. The system model is able to predict the performance indices, such as cooling capacity, efficiency, sensible heat ratio, etc. Using the calibrated system and heat exchanger models, we evaluated numerous low GWP (global warming potential) refrigerants. The predicted system performance indices, e.g. cooling efficiency, compressor discharge temperature, and required compressor displacement volume etc., are compared. Suitable replacements for R22 and R-410A for the room air conditioner application are recommended.

  17. NASA low speed centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Hathaway, Michael D.

    1990-01-01

    The flow characteristics of a low speed centrifugal compressor were examined at NASA Lewis Research Center to improve understanding of the flow in centrifugal compressors, to provide models of various flow phenomena, and to acquire benchmark data for three dimensional viscous flow code validation. The paper describes the objectives, test facilities' instrumentation, and experiment preliminary comparisons.

  18. Analysis of fully stalled compressor

    NASA Technical Reports Server (NTRS)

    Rostafinski, W.

    1986-01-01

    An analysis yields a model for energy transfer in compressor stages operating in the closed-throttle condition. The derivation indicates that three geometry parameters (hub/tip ration, aspect ration, and rotor blade setting angle) influence the values of pressure coefficient when the compressor flow is close to zero.

  19. NASA Glenn's Single-Stage Axial Compressor Facility Upgraded

    NASA Technical Reports Server (NTRS)

    Brokopp, Richard A.

    2004-01-01

    NASA Glenn Research Center's Single-Stage Axial Compressor Facility was upgraded in fiscal year 2003 to expand and improve its research capabilities for testing high-speed fans and compressors. The old 3000-hp drive motor and gearbox were removed and replaced with a refurbished 7000-hp drive motor and gearbox, with a maximum output speed of 21,240 rpm. The higher horsepower rating permits testing of fans and compressors with higher pressure ratio or higher flow. A new inline torquemeter was installed to provide an alternate measurement of fan and compressor efficiency, along with the standard pressure and temperature measurements. A refurbished compressor bearing housing was also installed with bidirectional rotation capability, so that a variety of existing hardware could be tested. Four new lubrication modules with backup capability were installed for the motor, gearbox, torquemeter, and compressor bearing housing, so that in case the primary pump fails, the backup will prevent damage to the rotating hardware. The combustion air supply line for the facility inlet air system was activated to provide dry air for repeatable inlet conditions. New flow conditioning hardware was installed in the facility inlet plenum tank, which greatly reduced the inlet turbulence. The new inlet can also be easily modified to accommodate 20- or 22-in.-diameter fans and compressors, so a variety of existing hardware from other facilities (such as Glenn's 9- by 15-Foot Low-Speed Wind Tunnel) can be tested in the Single-Stage Axial Compressor Facility. An exhaust line was also installed to provide bleed capability to remove the inlet boundary layer. To improve the operation and control of the facility, a new programmable logic controller (PLC) was installed to upgrade from hardwired relay logic to software logic. The PLC also enabled the usage of human-machine interface software to allow for easier operation of the facility and easier reconfiguration of the facility controls when

  20. QRFXFreeze: Queryable Compressor for RFX

    PubMed Central

    Senthilkumar, Radha; Nandagopal, Gomathi; Ronald, Daphne

    2015-01-01

    The verbose nature of XML has been mulled over again and again and many compression techniques for XML data have been excogitated over the years. Some of the techniques incorporate support for querying the XML database in its compressed format while others have to be decompressed before they can be queried. XML compression in which querying is directly supported instantaneously with no compromise over time is forced to compromise over space. In this paper, we propose the compressor, QRFXFreeze, which not only reduces the space of storage but also supports efficient querying. The compressor does this without decompressing the compressed XML file. The compressor supports all kinds of XML documents along with insert, update, and delete operations. The forte of QRFXFreeze is that the textual data are semantically compressed and are indexed to reduce the querying time. Experimental results show that the proposed compressor performs much better than other well-known compressors. PMID:26065027

  1. QRFXFreeze: Queryable Compressor for RFX.

    PubMed

    Senthilkumar, Radha; Nandagopal, Gomathi; Ronald, Daphne

    2015-01-01

    The verbose nature of XML has been mulled over again and again and many compression techniques for XML data have been excogitated over the years. Some of the techniques incorporate support for querying the XML database in its compressed format while others have to be decompressed before they can be queried. XML compression in which querying is directly supported instantaneously with no compromise over time is forced to compromise over space. In this paper, we propose the compressor, QRFXFreeze, which not only reduces the space of storage but also supports efficient querying. The compressor does this without decompressing the compressed XML file. The compressor supports all kinds of XML documents along with insert, update, and delete operations. The forte of QRFXFreeze is that the textual data are semantically compressed and are indexed to reduce the querying time. Experimental results show that the proposed compressor performs much better than other well-known compressors. PMID:26065027

  2. Practical experience with unstable compressors

    NASA Technical Reports Server (NTRS)

    Malanoski, S. B.

    1980-01-01

    Using analytical mathematical modeling techniques for the system components, an attempt is made to gauge the destabilizing effects in a number of compressor designs. In particular the overhung (or cantilevered) compressor designs and the straddle-mounted (or simply supported) compressor designs are examined. Recommendations are made, based on experiences with stable and unstable compressors, which can be used as guides in future designs. High and low pressure compressors which operate well above their fundamental rotor-bearing lateral natural frequencies can suffer from destructive subsynchronous vibration. Usually the elements in the system design which contribute to this vibration, other than the shafting and the bearings, are the seals (both gas labyrinth and oil breakdown bushings) and the aerodynamic components.

  3. Study on Reduction of Time Lag for Laser-Induced Electrical Discharge in Atmospheric Air with Non-Uniform Electric Field

    NASA Astrophysics Data System (ADS)

    Okano, Daisuke

    1998-11-01

    Study on Reduction of Time Lag for Laser-Induced Electrical Discharge in Atmospheric Air with Non-Uniform Electric Field* , Daisuke Okano, Kyushu Tokai University, 9-1-1 Toroku, Kumamoto, Japan. -----As an electrical discharge can be inductively occurred [1] by a pulsed laser-produced plasma (PLPP) in a rod-to-plate air gap stressed by a DC high voltage(Va), the starting point of laser-induced electrical discharge (LIED) is almost delayed more than few microseconds from focusing the laser beam. It is expected that the LIED by a PLPP is effectively occurred by reducing the time lag. The aim of our research focuses on the reduction for the time lag of LIED using CO2- and YAG pulsed lasers. The typical results are summarized as follows.The time lag of LIED in an atmospheric air gap (30mm) stressed at Va=30 kV is strongly reduced to 33 using CO2- and YAG pulsed lasers. The mechanism for the time lag of LIED is due to the electron attachment and detachment. [1] M.Inoue, T.Takashima, D.Okano et.al., Bull. of Inst. of Industrial Sci. & technical res.in Kyushu Tokai University, No.11 (1995)165 in Japanese. . *This work was supported by Grant-in-Aid for Scientific Research (C)-no.10650295 of The Ministry of education, Science Sports and Culture in japan.

  4. Rechargeability of Li-air cathodes pre-filled with discharge products using an ether-based electrolyte solution: implications for cycle-life of Li-air cells.

    PubMed

    Meini, Stefano; Tsiouvaras, Nikolaos; Schwenke, K Uta; Piana, Michele; Beyer, Hans; Lange, Lukas; Gasteiger, Hubert A

    2013-07-21

    The instability of currently used electrolyte solutions and of the carbon support during charge-discharge in non-aqueous lithium-oxygen cells can lead to discharge products other than the desired Li2O2, such as Li2CO3, which is believed to reduce cycle-life. Similarly, discharge in an O2 atmosphere which contains H2O and CO2 impurities would lead to LiOH and Li2CO3 discharge products. In this work we therefore investigate the rechargeability of model cathodes pre-filled with four possible Li-air cell discharge products, namely Li2O2, Li2CO3, LiOH, and Li2O. Using Online Electrochemical Mass Spectrometry (OEMS), we determined the charge voltages and the gases evolved upon charge of pre-filled electrodes, thus determining the reversibility of the formation/electrooxidation reactions. We show that Li2O2 is the only reversible discharge product in ether-based electrolyte solutions, and that the formation of Li2CO3, LiOH, or Li2O is either irreversible and/or reacts with the electrolyte solution or the carbon during its oxidation. PMID:23748698

  5. Performance of Compressor of XJ-41-V Turbojet Engine V-Performance Analysis of Compressor with Revised Vaned Collector over Range of Compressor Speeds from 3600 to 11,500 RPM

    NASA Technical Reports Server (NTRS)

    Ginsburg, Ambrose; Creagh, John W.R.; Michel, Donald

    1948-01-01

    An investigation of the XJ-41-V turbojet-engine compressor with a revised vaned collector was conducted to determine the performance of the compressor and to obtain fundamental information on the aerodynamic problems associated with large centrifugal compressors of this type. The original vaned collector was revised by increasing the flow area at the vaned collector entrance. A maximum adiabatic efficiency of 0.81 was obtained et a corrected weight flow of 36.5 pounds per second and a pressure ratio of 1.90. The peak pressure ratio was 3.93 and occurred at an impeller speed of 11,500 rpm at a corrected weight flow of 65.5 pounds per second. Revision of the vaned collector resulted in an increased airflow capacity over the speed range. The design air-flow capacity of 78 pounds per second was very nearly reached at the engine design speed of 11,500 rpm. The compressor air-flow choking point occurred in the vaned collector passage; however, at speeds above 8300 rpm, the air-flow capacity of the impeller was being approached as indicated by large pressure losses in the impeller at maximum air-flow conditions. An increase in compressor air-flow capacity at the higher speeds can possibly be obtained 5y removal of the flow restriction in the impeller, which would result in an increased air density at the vaned collector entrance.

  6. Aerodynamic Design of Axial Flow Compressors

    NASA Technical Reports Server (NTRS)

    Bullock, R. O. (Editor); Johnsen, I. A.

    1965-01-01

    An overview of 'Aerodynamic systems design of axial flow compressors' is presented. Numerous chapters cover topics such as compressor design, ptotential and viscous flow in two dimensional cascades, compressor stall and blade vibration, and compressor flow theory. Theoretical aspects of flow are also covered.

  7. 17. Governor Accumulator Tank Compressor and motor located along rear ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. Governor Accumulator Tank Compressor and motor located along rear corridor between Units 3 and 4, view to the west. The compressor motor is located just right of center in photograph. The pressure tank on the right side of the photograph is a reserve pressure tank for governor system. The pressure tank on the left side of the photograph is the original instrument air pressure tank. - Washington Water Power Clark Fork River Noxon Rapids Hydroelectric Development, Powerhouse, South bank of Clark Fork River at Noxon Rapids, Noxon, Sanders County, MT

  8. Hermetic compressor and block expansion valve in refrigeration performance

    NASA Astrophysics Data System (ADS)

    Santoso, Budi; Susilo, Didik Djoko; Tjahjana, D. D. D. P.

    2016-03-01

    Vehicle cabin in tropical countries requires the cooling during the day for comfort of passengers. Air conditioning machine is commonly driven by an internal combustion engine having a great power, which the conventional compressor is connected to crank shaft. The stage of research done is driving the hermetic compressor with an electric motor, and using block expansion valve. The HFC-134a was used as refrigerant working. The primary parameters observed during the experiment are pressure, temperature, and power consumption for different cooling capacities. The results show that the highest coefficient of performance (COP) and the electric power of system are 6.3 and 638 Watt, respectively.

  9. Reverse-Tangent Injection in a Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.

    2007-01-01

    Injection of working fluid into a centrifugal compressor in the reverse tangent direction has been invented as a way of preventing flow instabilities (stall and surge) or restoring stability when stall or surge has already commenced. The invention applies, in particular, to a centrifugal compressor, the diffuser of which contains vanes that divide the flow into channels oriented partly radially and partly tangentially. In reverse-tangent injection, a stream or jet of the working fluid (the fluid that is compressed) is injected into the vaneless annular region between the blades of the impeller and the vanes of the diffuser. As used here, "reverse" signifies that the injected flow opposes (and thereby reduces) the tangential component of the velocity of the impeller discharge. At the same time, the injected jet acts to increase the radial component of the velocity of the impeller discharge.

  10. Performance of J33-A-21 and J33-A-23 Turbojet-Engine Compressors with Water Injection

    NASA Technical Reports Server (NTRS)

    Beede, William L.; Withee, Joseph R., Jr.

    1949-01-01

    As part of the performance investigation of compressors for the J33 turbojet engine, the A-21 model and the A-23 model with a 17- and a 34-blade impeller were operated with water injection at their respective design equivalent speeds of 11,500 and 11,750 rpm. Inlet conditions of pressure of 14 inches of mercury absolute and of ambient temperature correspond to those of the investigation of these models without water injection. The water-air ratio by weight ranged from 0.05 to 0.06. By the use of water injection, the peak pressure ratio of the A-21 compressor and the A-23 compressor with a 34-blade impeller increased approximately 0.38, whereas that of the A-23 compressor with a 17-blade impeller increased only 0.14. The decrease in maximum efficiency for the three compressors ranged from 0.12 to 0.14. The highest increase in maximum equivalent weight flow of air plus weight flow of water was 10.90 pounds per second obtained with the A-21 compressor. The increase in air weight flow alone was approximately 5.70 pounds per second for the A-21 compressor end the A-23, 17-blade compressor, which exceeded the increase of 3.15 pounds per second for the A-23; 34-blade compressor.

  11. Comprehensive Compressor Calorimeter Testing of Lower-GWP Alternative Refrigerants for Heat Pump and Medium Temperature Refrigeration Applications

    SciTech Connect

    Shrestha, Som S; Sharma, Vishaldeep; Abdelaziz, Omar

    2014-01-01

    In response to environmental concerns raised by the use of refrigerants with high Global Warming Potential (GWP), the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) has launched an industry-wide cooperative research program, referred to as the Low-GWP Alternative Refrigerants Evaluation Program (AREP), to identify and evaluate promising alternative refrigerants for major product categories. This paper reports one of the Oak Ridge National Laboratory (ORNL) contributions to AREP. It compares performance of alternative refrigerants to that of R-410A and R-404A for heat pump and medium temperature applications, respectively. The alternatives reported in this paper are: R-32, DR-5, and L-41a for R-410A and ARM-31a, D2Y-65, L-40, and a mixture of R-32 and R-134a for R-404A. All performance comparison tests were conducted using scroll compressors of ~1.85 tons (6.5 kW) cooling capacity. Tests were conducted over a range of combinations of saturation suction and saturation discharge temperatures for both compressors. The tests showed that, in general, energy efficiency ratio (EER) and cooling capacity of R-410A alternative refrigerants were slightly lower than that of the baseline refrigerant with a moderate increases in discharge temperature. On the other hand, R-404A alternative refrigerants showed relative performance dependence on saturation suction and saturation discharge temperatures and larger increases in discharge temperature than for the R-410A alternatives. This paper summarizes the relative performance of all alternative refrigerants compared to their respective baseline.

  12. Wave Augmented Diffuser for Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J. (Inventor); Paxson, Daniel E. (Inventor)

    2001-01-01

    A wave augmented diffuser for a centrifugal compressor surrounds the outlet of an impeller that rotates on a drive shaft having an axis of rotation. The impeller brings flow in in an axial direction and imparts kinetic energy to the flow discharging it in radial and tangential directions. The flow is discharged into a plurality of circumferentially disposed wave chambers. The wave chambers are periodically opened and closed by a rotary valve such that the flow through the diffuser is unsteady. The valve includes a plurality of valve openings that are periodically brought into and out of fluid communication with the wave chambers. When the wave chambers are closed, a reflected compression wave moves upstream towards the diffuser bringing the flow into the wave chamber to rest. This action recovers the kinetic energy from the flow and limits any boundary layer growth. The flow is then discharged in an axial direction through an opening in the valve plate when the valve plate is rotated to an open position. The diffuser thus efficiently raises the static pressure of the fluid and discharges an axially directed flow at a radius that is predominantly below the maximum radius of the diffuser.

  13. Centrifugal Compressor Aeroelastic Analysis Code

    NASA Astrophysics Data System (ADS)

    Keith, Theo G., Jr.; Srivastava, Rakesh

    2002-01-01

    Centrifugal compressors are very widely used in the turbomachine industry where low mass flow rates are required. Gas turbine engines for tanks, rotorcraft and small jets rely extensively on centrifugal compressors for rugged and compact design. These compressors experience problems related with unsteadiness of flowfields, such as stall flutter, separation at the trailing edge over diffuser guide vanes, tip vortex unsteadiness, etc., leading to rotating stall and surge. Considerable interest exists in small gas turbine engine manufacturers to understand and eventually eliminate the problems related to centrifugal compressors. The geometric complexity of centrifugal compressor blades and the twisting of the blade passages makes the linear methods inapplicable. Advanced computational fluid dynamics (CFD) methods are needed for accurate unsteady aerodynamic and aeroelastic analysis of centrifugal compressors. Most of the current day industrial turbomachines and small aircraft engines are designed with a centrifugal compressor. With such a large customer base and NASA Glenn Research Center being, the lead center for turbomachines, it is important that adequate emphasis be placed on this area as well. Currently, this activity is not supported under any project at NASA Glenn.

  14. Centrifugal Compressor Aeroelastic Analysis Code

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Srivastava, Rakesh

    2002-01-01

    Centrifugal compressors are very widely used in the turbomachine industry where low mass flow rates are required. Gas turbine engines for tanks, rotorcraft and small jets rely extensively on centrifugal compressors for rugged and compact design. These compressors experience problems related with unsteadiness of flowfields, such as stall flutter, separation at the trailing edge over diffuser guide vanes, tip vortex unsteadiness, etc., leading to rotating stall and surge. Considerable interest exists in small gas turbine engine manufacturers to understand and eventually eliminate the problems related to centrifugal compressors. The geometric complexity of centrifugal compressor blades and the twisting of the blade passages makes the linear methods inapplicable. Advanced computational fluid dynamics (CFD) methods are needed for accurate unsteady aerodynamic and aeroelastic analysis of centrifugal compressors. Most of the current day industrial turbomachines and small aircraft engines are designed with a centrifugal compressor. With such a large customer base and NASA Glenn Research Center being, the lead center for turbomachines, it is important that adequate emphasis be placed on this area as well. Currently, this activity is not supported under any project at NASA Glenn.

  15. Review - Axial compressor stall phenomena

    NASA Technical Reports Server (NTRS)

    Greitzer, E. M.

    1980-01-01

    Stall in compressors can be associated with the initiation of several types of fluid dynamic instabilities. These instabilities and the different phenomena, surge and rotating stall, which result from them, are discussed in this paper. Assessment is made of the various methods of predicting the onset of compressor and/or compression system instability, such as empirical correlations, linearized stability analyses, and numerical unsteady flow calculation procedures. Factors which affect the compressor stall point, in particular inlet flow distortion, are reviewed, and the techniques which are used to predict the loss in stall margin due to these factors are described. The influence of rotor casing treatment (grooves) on increasing compressor flow range is examined. Compressor and compression system behavior subsequent to the onset of stall is surveyed, with particular reference to the problem of engine recovery from a stalled condition. The distinction between surge and rotating stall is emphasized because of the very different consequences on recoverability. The structure of the compressor flow field during rotating stall is examined, and the prediction of compressor performance in rotating stall, including stall/unstall hysteresis, is described.

  16. Downhole steam generator having a downhole oxidant compressor

    DOEpatents

    Fox, Ronald L.

    1983-01-01

    Apparatus and method for generation of steam in a borehole for penetration into an earth formation wherein a downhole oxidant compressor is used to compress relatively low pressure (atmospheric) oxidant, such as air, to a relatively high pressure prior to mixing with fuel for combustion. The multi-stage compressor receives motive power through a shaft driven by a gas turbine powered by the hot expanding combustion gases. The main flow of compressed oxidant passes through a velocity increasing nozzle formed by a reduced central section of the compressor housing. An oxidant bypass feedpipe leading to peripheral oxidant injection nozzles of the combustion chamber are also provided. The downhole compressor allows effective steam generation in deep wells without need for high pressure surface compressors. Feedback preheater means are provided for preheating fuel in a preheat chamber. Preheating of the water occurs in both a water feed line running from aboveground and in a countercurrent water flow channel surrounding the combustor assembly. The countercurrent water flow channels advantageously serve to cool the combustion chamber wall. The water is injected through slotted inlets along the combustion chamber wall to provide an unstable boundary layer and stripping of the water from the wall for efficient steam generation. Pressure responsive doors are provided at the steam outlet for closing and sealing the combustion chamber from entry of reservoir fluids in the event of a flameout.

  17. Causes of high pressure compressor deterioration in service

    NASA Technical Reports Server (NTRS)

    Richardson, J. H.; Sallee, G. P.; Smakula, F. K.

    1979-01-01

    The high mechanical reliability and low deterioration rate of the JT9D high-pressure compressor results in long utilization without exceeding engine operational limits. The increasing cost and decreasing supply of fuel have focused attention on the fuel burned implications of such high time use without refurbishment. The paper presents the results of JT9D high pressure compressor studies. The mechanical deterioration of the JT9D high-pressure compressor gaspath parts versus increasing service usage, documented from inspection of service parts, is presented and discussed including changes in airfoil roughness, blade length, airfoil contour and outer air seal trench characteristics. An estimate of the performance loss versus usage is related to each type of damage. The combined estimated high-pressure compressor performance loss for all mechanisms determined from part inspection is compared to historical engine test data to establish the validity of the predicted loss levels. The effect of cold section refurbishment on engine fuel consumption recovery and the results of an optimization study to determine the appropriate interval for high pressure compressor refurbishment are also reported.

  18. Downhole steam generator having a downhole oxidant compressor

    SciTech Connect

    Fox, R.L.

    1983-04-19

    Apparatus and method for generation of steam in a borehole for penetration into an earth formation wherein a downhole oxidant compressor is used to compress relatively low pressure (Atmospheric) oxidant, such as air, to a relatively high pressure prior to mixing with fuel for combustion. The multi-stage compressor receives motive power through a shaft driven by a gas turbine powered by the hot expanding combustion gases. The main flow of compressed oxidant passes through a velocity increasing nozzle formed by a reduced central section of the compressor housing. An oxidant bypass feedpipe leading to peripheral oxidant injection nozzles of the combustion chamber are also provided. The downhole compressor allows effective steam generation in deep wells without need for high pressure surface compressors. Feedback preheater means are provided for preheating fuel in a preheat chamber. Preheating of the water occurs in both a water feed line running from aboveground and in a countercurrent water flow channel surrounding the combustor assembly. The countercurrent water flow channels advantageously serve to cool the combustion chamber wall. The water is injected through slotted inlets along the combustion chamber wall to provide an unstable boundary layer and stripping of the water from the wall for efficient steam generation. Pressure responsive doors are provided at the steam outlet for closing and sealing the combustion chamber from entry of reservoir fluids in the event of a flameout.

  19. The Multistage Compressor Facility

    NASA Technical Reports Server (NTRS)

    Flegel, Ashlie

    2004-01-01

    Research and developments of new aerospace technologies is one of Glenn Research Center's specialties. One facility that deals with the research of aerospace technologies is the High-speed Multistage Compressor Facility. This facility will be testing the performance and efficiency of an Ultra Efficient Engine Technology (UEET) two-stage compressor. There is a lot of preparation involved with testing something of this caliber. Before the test article can be installed into the test rig, the facility must be fully operational and ready to run. Meaning all the necessary instrumentation must be calibrated and installed in the facility. The test rig should also be in safe operating condition, and the proper safety permits obtained. In preparation for the test, the Multistage Compressor Facility went through a few changes. For instance the facility will now be utilizing slip rings, the gearbox went through some maintenance, new lubrications systems replaced the old ones, and special instrumentation needs to be fine tuned to achieve the maximum amount of accurate data. Slips rings help gather information off of a rotating device - in this case from a shaft - onto stationary contacts. The contacts (or brushes) need to be cooled to reduce the amount of frictional heat produced between the slip ring and brushes. The coolant being run through the slip ring is AK-225, a material hazardous to the ozone. To abide by the safety regulations the coolant must be run through a closed chiller system. A new chiller system was purchased but the reservoir that holds the coolant was ventilated which doesn t make the system truly closed and sealed. My task was to design and have a new reservoir built for the chiller system that complies with the safety guidelines. The gearbox had some safety issues also. Located in the back of the gearbox an inching drive was set up. When the inching drive is in use the gears and chain are bare and someone can easily get caught up in it. So to prevent

  20. A Blast of Cool Air

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Unable to solve their engineering problem with a rotor in their Orbital Vane product, DynEco Corporation turned to Kennedy Space Center for help. KSC engineers determined that the compressor rotor was causing a large concentration of stress, which led to cracking and instant rotor failure. NASA redesigned the lubrication system, which allowed the company to move forward with its compressor that has no rubbing parts. The Orbital Vane is a refrigerant compressor suitable for mobile air conditioning and refrigeration.