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1

High-Energy Electromagnetic Conversion Processes in Intense Magnetic Fields  

Microsoft Academic Search

General characteristics of magnetic bremsstrahlung (synchrotron radiation) are derived on the basis of calculations utilizing exact relativistic matrix elements. The spectral and total energy losses may be described by compact expressions incorporating radiative and quantum corrections. Comparisons of the relative efficacy of matter and magnetic fields as bremsstrahlung radiators indicate that even under relatively conservative conditions the natural conversion rates

Thomas Erber

1966-01-01

2

Permanent magnet synchronous generators for regenerative energy conversion - a survey  

Microsoft Academic Search

A survey on recently installed or developed permanent magnet (PM) synchronous generators for energy conversion in regenerative and alternative power supply systems is given. Its focus is for low speed machines on geared and gearless PM generator systems for wind power plants and small PM hydro generators in gearless coupling. For distributed co-generation of heat and electrical power by micro

Andreas Binder; Tobias Schneider

2005-01-01

3

Permanent magnet energy conversion machine with magnet mounting arrangement  

DOEpatents

A hybrid permanent magnet dc motor includes three sets of permanent magnets supported by the rotor and three sets of corresponding stators fastened to the surrounding frame. One set of magnets operates across a radial gap with a surrounding radial gap stator, and the other two sets of magnets operate off the respective ends of the rotor across respective axial gaps.

Hsu, John S. (Oak Ridge, TN); Adams, Donald J. (Knoxville, TN)

1999-01-01

4

Conversion of magnetic energy in the magnetic reconnection layer of a laboratory plasma  

NASA Astrophysics Data System (ADS)

Magnetic reconnection, in which magnetic field lines break and reconnect to change their topology, occurs throughout the universe. The essential feature of reconnection is that it energizes plasma particles by converting magnetic energy. Despite the long history of reconnection research, how this energy conversion occurs remains a major unresolved problem in plasma physics. Here we report that the energy conversion in a laboratory reconnection layer occurs in a much larger region than previously considered. The mechanisms for energizing plasma particles in the reconnection layer are identified, and a quantitative inventory of the converted energy is presented for the first time in a well-defined reconnection layer; 50% of the magnetic energy is converted to particle energy, 2/3 of which transferred to ions and 1/3 to electrons. Our results are compared with simulations and space measurements, for a key step towards resolving one of the most important problems in plasma physics.

Yamada, Masaaki; Yoo, Jongsoo; Jara-Almonte, Jonathan; Ji, Hantao; Kulsrud, Russell M.; Myers, Clayton E.

2014-09-01

5

Multiphysics simulation of wave energy to electric energy conversion by permanent magnet linear generator  

Microsoft Academic Search

The possibility to use three-phase permanent magnet linear generators to convert sea wave energy into electric energy is investigated by multiphysics simulations. The results show a possibility, which needs to be further verified by experimental tests, for a future step toward a sustainable electric power production from ocean waves by using direct conversion. The results suggest that wave energy can

Mats Leijon; Hans Bernhoff; Olov Ågren; Jan Isberg; Jan Sundberg; Marcus Berg; Karl Erik Karlsson; Arne Wolfbrandt

2005-01-01

6

Scaling the energy conversion rate from magnetic field reconnection to different bodies  

SciTech Connect

Magnetic field reconnection is often invoked to explain electromagnetic energy conversion in planetary magnetospheres, stellar coronae, and other astrophysical objects. Because of the huge dynamic range of magnetic fields in these bodies, it is important to understand energy conversion as a function of magnetic field strength and related parameters. It is conjectured theoretically and shown experimentally that the energy conversion rate per unit area in reconnection scales as the cube of an appropriately weighted magnetic field strength divided by the square root of an appropriately weighted density. With this functional dependence, the energy release in flares on the Sun, the large and rapid variation of the magnetic flux in the tail of Mercury, and the apparent absence of reconnection on Jupiter and Saturn, may be understood. Electric fields at the perihelion of the Solar Probe Plus mission may be tens of V/m.

Mozer, F. S.; Hull, A. [Space Sciences Laboratory, University of California, Berkeley, California 94720 (United States)

2010-10-15

7

Three-phase Four-wire Autonomous Wind Energy Conversion System Using Permanent Magnet Synchronous Generator  

Microsoft Academic Search

This article deals with an autonomous wind energy conversion system employing a permanent magnet synchronous generator feeding three-phase four-wire local loads in stand-alone mode without using a mechanical position sensor. The proposed autonomous wind energy conversion system utilizes two back-to-back connected pulse width modulated insulated gate bipolar transistors based voltage source converters with a battery energy storage system at their

Puneet K. Goel; Bhim Singh; S. S. Murthy; Shailendra K. Tiwari

2010-01-01

8

Energy conversion and transfer for plasmas in a magnetic expansion configuration  

SciTech Connect

A two-dimensional axisymmetric particle-in-cell code with Monte Carlo collision conditions has been used to study particle energy transfer in plasmas and conversion in applied magnetic and electric fields appropriate to coaxial acceleration. The research incorporates a computation scheme with: a model of single particle magnetic interactions; a model of single particle interactions in electric and magnetic fields; and a model of multi-particle collisional interactions in order to understand the energy transfer processes and conversion mechanisms of charged plasma particles. This approach predicts electron and ion motions along with their energy variations for physical conditions that occur in the related models; the results allow comparison with experimental data for magnetic field strengths of 0.01–0.05?T and electrode voltages of 22.0–32.0?V. With the incorporation of magnetic and electric field effects on charged particles, the multi-particle model includes electron-neutral ionization collisions, ion-neutral charge exchange collisions, and electron-ion Coulomb collisions. This research presents a new approach to achieve an underlying understanding of the plasma energy transfer and conversion in the external electric and magnetic fields that is not possible using magnetohydrodynamics continuum representations. Results indicate the following innovative conclusions: (1) Radial and azimuthal energies of magnetized electrons are converted into an axial electron energy component in the diverging magnetic field, and the azimuthal kinetic energy of unmagnetized ions is converted into axial and radial components. (2) In electric and magnetic fields, electric field energy is primarily converted into axial kinetic energy of magnetized electrons by the energy transformation effects of magnetic fields, and for unmagnetized ions, the radial kinetic energy component dominates in the conversion of electric field energy. (3) For the collisional plasma, electron kinetic energy tends to increase (or decrease) to a terminal value since electrons lose energy in collisions then gain energy again from the field. Ions acquire most energy directly from the electric field, although part of the electric field energy arrives to the ions by collisions. Further, the ion axial energy component dominates the total ion energy. The collision processes are found to be integral and essential for the conversion of the plasma non-directed energy gain to be converted into the resultant axial energy, the magnitudes of which are found to be in agreement with experimental results.

Cheng, Jiao [Beihang University, Beijing 100191 (China); Shanghai Engineering Center for Microsatellites, Shanghai 201203 (China); Tang, Hai-Bin, E-mail: thb@buaa.edu.cn [Beihang University, Beijing 100191 (China); York, Thomas M. [Aeronautical and Astronautical Engineering Department, Ohio State University, Columbus, Ohio 43210 (United States)

2014-06-15

9

Energy Conversions  

NSDL National Science Digital Library

Students evaluate various everyday energy conversion devices and draw block flow diagrams to show the forms and states of energy into and out of the device. They also identify the forms of energy that are useful and the desired output of the device as well as the forms that are not useful for the intended use of the item. This can be used to lead into the law of conservation of energy and efficiency. The student activity is preceded by a demonstration of a more complicated system to convert chemical energy to heat energy to mechanical energy. Drawing the block energy conversion diagram for this system models the activity that the students then do themselves for other simpler systems.

2014-09-18

10

VOLUME54, NUMBER9 PHYSICAL REVIEW LETTERS 4 MARCH1985 Conversion of Wave Energy to Magnetic Field Energy in a Plasma Torus  

E-print Network

VOLUME54, NUMBER9 PHYSICAL REVIEW LETTERS 4 MARCH1985 Conversion of Wave Energy to Magnetic Field into plasma heating so that the conversion efficiency of rf energy to po- loidal field energy, given. Evidently, P,JP- 1. This points to a regime for efficient energy conversion except for two further effects

Karney, Charles

11

862 IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 26, NO. 3, SEPTEMBER 2011 Analytical Method for Magnetic Field Calculation in  

E-print Network

862 IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 26, NO. 3, SEPTEMBER 2011 Analytical Method to achieve energy conversion and transmission. The detailed knowledge of the field distributions in the air element method. Index Terms--Analytical calculation, direct drive, harmonic ma- chine, low speed, magnetic

Mi, Chunting "Chris"

12

Received 5 May 2014 | Accepted 23 Jul 2014 | Published 10 Sep 2014 Conversion of magnetic energy in the magnetic  

E-print Network

. Despite the long history of reconnection research, how this energy conversion occurs remains a major unresolved problem in plasma physics. Here we report that the energy conversion in a laboratory reconnection of this efficient energy conversion is the observation of large amounts of high- energy electrons associated

13

Magnetic flux conversion and relaxation toward a minimum-energy state in S-1 spheromak plasmas  

SciTech Connect

S-1 Spheromak currents and magnetic fluxes have been measured with Rogowski coils and flux loops external to the plasma. Toroidal plasma currents up to 350 kA and spheromak configuration lifetimes over 1.0 msec have been achieved at moderate power levels. The plasma formation in the S-1 Spheromak device is based on an inductive transfer of poloidal and toroidal magnetic flux from a toroidal ''flux core'' to the plasma. Formation is programmed to guide the configuration into a force-free, minimum-energy Taylor state. Properly detailed programming of the formation process is found not to be essential since plasmas adjust themselves during formation to a final equilibrium near the Taylor state. After formation, if the plasma evolves away from the stable state, then distinct relaxation oscillation events occur which restore the configuration to that stable state. The relaxation process involves reconnection of magnetic field lines, and conversion of poloidal to toroidal magnetic flux (and vice versa) has been observed and documented. The scaling of toroidal plasma current and toroidal magnetic flux in the plasma with externally applied currents is consistent with the establishment of a Taylor state after formation. In addition, the magnetic helicity is proportional to that injected from the flux core, independent of how that helicity is generated.

Janos, A.

1985-09-01

14

Solar energy conversion  

Microsoft Academic Search

The physical nature of solar radiation, some history of direct solar energy conversion, and descriptions of conversion methods are discussed. Several conversion methods are reviewed, including photosynthesis, solar cells, and solar thermal conversion. (SPH)

Maddox

1974-01-01

15

EFFICIENCY OF MAGNETIC TO KINETIC ENERGY CONVERSION IN A MONOPOLE MAGNETOSPHERE  

SciTech Connect

Unconfined relativistic outflows from rotating, magnetized compact objects are often well modeled by assuming that the field geometry is approximately a split-monopole at large radii. Earlier work has indicated that such an unconfined flow has an inefficient conversion of magnetic energy to kinetic energy. This has led to the conclusion that ideal magnetohydrodynamical (MHD) processes fail to explain observations of, e.g., the Crab pulsar wind at large radii where energy conversion appears efficient. In addition, as a model for astrophysical jets, the monopole field geometry has been abandoned in favor of externally confined jets since the latter appeared to be generically more efficient jet accelerators. We perform time-dependent axisymmetric relativistic MHD simulations in order to find steady-state solutions for a wind from a compact object endowed with a monopole field geometry. Our simulations follow the outflow for 10 orders of magnitude in distance from the compact object, which is large enough to study both the initial 'acceleration zone' of the magnetized wind as well as the asymptotic 'coasting zone'. We obtain the surprising result that acceleration is actually efficient in the polar region, which develops a jet despite not being confined by an external medium. Our models contain jets that have sufficient energy to account for moderately energetic long and short gamma-ray burst (GRB) events ({approx}10{sup 51}-10{sup 52} erg), collimate into narrow opening angles (opening half-angle {theta} {sub j} {approx} 0.03 rad), become matter-dominated at large radii (electromagnetic energy flux per unit matter energy flux {sigma} < 1), and move at ultrarelativistic Lorentz factors ({gamma} {sub j} {approx} 200 for our fiducial model). The simulated jets have {gamma} {sub j}{theta} {sub j} {approx} 5-15, so they are in principle capable of generating 'achromatic jet breaks' in GRB afterglow light curves. By defining a 'causality surface' beyond which the jet cannot communicate with a generalized 'magnetic nozzle' near the axis of rotation, we obtain approximate analytical solutions for the Lorentz factor that fit the numerical solutions well. This allows us to extend our results to monopole wind models with arbitrary magnetization. Overall, our results demonstrate that the production of ultrarelativistic jets is a more robust process than previously thought.

Tchekhovskoy, Alexander [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 10, Cambridge, MA 02138 (United States); McKinney, Jonathan C. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, P.O. Box 20450, MS 29, Stanford, CA 94309 (United States); Narayan, Ramesh [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 51, Cambridge, MA 02138 (United States)], E-mail: atchekho@cfa.harvard.edu, E-mail: jmckinne@stanford.edu, E-mail: rnarayan@cfa.harvard.edu

2009-07-10

16

Direct Conversion of Energy.  

ERIC Educational Resources Information Center

This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics…

Corliss, William R.

17

Novel fusion energy conversion methods  

Microsoft Academic Search

The potential importance of direct energy conversion to the long-term development of fusion power is discussed with emphasis on the possibility of alleviating waste heat problems. This is envisioned to be important for any central power station in the 21st century and crucial for future space applications. Various novel conversion methods are briefly considered, including direct collection, magnetic expansion, synchroton

L. J. Perkins; G. H. Miley; B. G. Logan

1988-01-01

18

ENERGY CONVERSION Spring 2011  

E-print Network

: Topics in Renewable/Sustainable Energy Conversion An engineering design project will be assigned1 ENSC 461 ENERGY CONVERSION Spring 2011 Instructor: Dr. Majid Bahrami 4372 Email will analyze thermal systems and energy conversion devices on the basis of the laws of thermodynamics. A main

Bahrami, Majid

19

Energy conversion alternatives study  

NASA Technical Reports Server (NTRS)

Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.

Shure, L. T.

1979-01-01

20

Electrodynamic conversion of energy - Magnetic field amplification in the solar photosphere  

NASA Astrophysics Data System (ADS)

Velocities of electrons, ions, and neutrals are computed, in the three-fluid approximation for an axisymmetrical magnetic field. By prescribing a radial dependence of the velocity of neutrals, in agreement with a downflow, the radial dependence of the magnetic field energy density is derived. This gives the radial flux of neutrals that is required to increase the magnetic field in the photosphere from 5 to 1000 Gauss. The hypothesis of local cooling by advection of ionization energy of Schatten and Mayr (1985) is tested, showing that this flux of neutrals is high enough to significantly affect the energy balance in the tube and to maintain the pressure gradient necessary to produce the radial inflow of neutrals.

Henoux, J. C.; Somov, B. V.

21

High-energy neutrino conversion into electron-W pair in magnetic field and its contribution to neutrino absorption  

E-print Network

We calculate the conversion rate of high-energy neutrinos propagating in constant magnetic field into an electron-W pair (nu -> W + e) from the imaginary part of the neutrino self-energy. Using the exact propagators in constant magnetic field, the neutrino self-energy has been calculated to all order in the field within the Weinberg-Salam model. We obtain a compact formula in the limit of B << Bcr = m^2/e. We find that above the process threshold Eth \\~ 2.2 10^16 (Bcr / B) eV this contribution to the absorption of neutrinos yields an asymptotic absorption length ~ 1.1 (Bcr / B)^2 (10^{16} eV / E) meters.

Andrea Erdas; Marcello Lissia

2003-02-17

22

Direct energy conversion  

Microsoft Academic Search

A comprehensive review of methods for direct energy conversion and energy storage is presented.Included are selected applications and brief reviews of underlying principles of each method. Principal chapter coverage is devoted to thermoelectric, photovoltaic, thermionic and magnetohydrodynamic generators. Other modes of energy conversion briefly covered are as follows: Nernst effect, ferroelectric, thermomagnetic, thermo-photo-voltaic, electrohydrodynamic, electrokinetic, piezoelectric, radiation, direct charging devices,

Angrist

1976-01-01

23

Evaluating Energy Conversion Efficiency  

NASA Technical Reports Server (NTRS)

Devices that convert solar radiation directly into storable chemical or electrical energy, have characteristic energy absorption spectrum; specifically, each of these devices has energy threshold. The conversion efficiency of generalized system that emcompasses all threshold devices is analyzed, resulting in family of curves for devices of various threshold energies operating at different temperatures.

Byvik, C. E.; Smith, B. T.; Buoncristiani, A. M.

1983-01-01

24

Regional Energy Conversations Report  

NSDL National Science Digital Library

In 2009 and 2010, ATEEC facilitated a series of seven regional Energy Conversations. The primary purpose of the conversations was to obtain a snapshot view of existing and upcoming energy jobs and to determine which jobs are currently needed in different regions of the country, including the Mid-Atlantic, North Central, Northwest, South Central, Southeast, Southwest, and West. The resulting report on these Energy Conversations is intended to provide a preliminary labor market analysis and needs assessment. This information allows educational organizations to most effectively target regional energy industry requirements and to provide both short-and long-term education and training for the energy technicians of the 21st century workforce. Ultimately, this report should contribute to addressing the workforce development needs of business, industry, and government by providing educators with information needed to develop relevant curriculum that prepares students for energy technology careers.

2010-01-05

25

Energy conversion engineering  

Microsoft Academic Search

The book represents a teaching text and not a state-of-the-art review or a data source book on energy conversion systems. The information presented aims at providing some of the analytical tools that will allow many of the arguments about energy policy to be reduced to numerical values. The discussion covers the laws of thermodynamics, chemical equilibrium, chemical reaction kinetics, and

R. C. Bailie

1978-01-01

26

Solar energy conversion.  

SciTech Connect

If solar energy is to become a practical alternative to fossil fuels, we must have efficient ways to convert photons into electricity, fuel, and heat. The need for better conversion technologies is a driving force behind many recent developments in biology, materials, and especially nanoscience. The Sun has the enormous untapped potential to supply our growing energy needs. The barrier to greater use of the solar resource is its high cost relative to the cost of fossil fuels, although the disparity will decrease with the rising prices of fossil fuels and the rising costs of mitigating their impact on the environment and climate. The cost of solar energy is directly related to the low conversion efficiency, the modest energy density of solar radiation, and the costly materials currently required. The development of materials and methods to improve solar energy conversion is primarily a scientific challenge: Breakthroughs in fundamental understanding ought to enable marked progress. There is plenty of room for improvement, since photovoltaic conversion efficiencies for inexpensive organic and dye-sensitized solar cells are currently about 10% or less, the conversion efficiency of photosynthesis is less than 1%, and the best solar thermal efficiency is 30%. The theoretical limits suggest that we can do much better. Solar conversion is a young science. Its major growth began in the 1970s, spurred by the oil crisis that highlighted the pervasive importance of energy to our personal, social, economic, and political lives. In contrast, fossil-fuel science has developed over more than 250 years, stimulated by the Industrial Revolution and the promise of abundant fossil fuels. The science of thermodynamics, for example, is intimately intertwined with the development of the steam engine. The Carnot cycle, the mechanical equivalent of heat, and entropy all played starring roles in the development of thermodynamics and the technology of heat engines. Solar-energy science faces an equally rich future, with nanoscience enabling the discovery of the guiding principles of photonic energy conversion and their use in the development of cost-competitive new technologies.

Crabtree, G. W.; Lewis, N. S. (Materials Science Division); (California Inst. of Tech.)

2008-03-01

27

Energy conversion system  

Microsoft Academic Search

An energy conversion system is described for the production of power from hot fluid sources which may contain dissolved solutes and undesirable noncondensable gases. Direct heat transfer is utilized by the hot fluid sources to vaporize a working fluid which is then in turn utilized for the production of power. In the given system the working fluid is employed in

Schwartzman

1978-01-01

28

Photovoltaic Energy Conversion  

E-print Network

/ (unit area unit time) #12;Ultimate Efficiency Incident solar power: in = s Electrical output power: out Make solar cells more efficient Theoretical energy conversion efficiency limit of single junction solar cell is 31% Actual efficiencies are even lower: ~20% Make solar cells cheaper "Grid Parity

Glashausser, Charles

29

Electromechanical Energy Conversion.  

ERIC Educational Resources Information Center

This programed text on electromechanical energy conversion (motors and generators) was developed under contract with the U.S. Office of Education as Number 12 in a series of materials for use in an electrical engineering sequence. It is intended to be used in conjunction with other materials and with other short texts in the series. (DH)

LePage, Wilbur R.

30

Energy-mass conversion  

NSDL National Science Digital Library

How do physicists make new particles? In this page of a particle physics tutorial, students are introduced to the concept of converting kinetic energy to mass. Students read that low-mass particles placed into an accelerator can be smashed together to produce more massive particles through the conversion of energy to mass. They see an example in which two pieces of fruit are accelerated and smashed, and additional types of fruit are produced. Copyright 2005 Eisenhower National Clearinghouse

Group, Lawrence B.

2002-01-01

31

Electromagnetic energy conversion at reconnection fronts.  

PubMed

Earth's magnetotail contains magnetic energy derived from the kinetic energy of the solar wind. Conversion of that energy back to particle energy ultimately powers Earth's auroras, heats the magnetospheric plasma, and energizes the Van Allen radiation belts. Where and how such electromagnetic energy conversion occurs has been unclear. Using a conjunction between eight spacecraft, we show that this conversion takes place within fronts of recently reconnected magnetic flux, predominantly at 1- to 10-electron inertial length scale, intense electrical current sheets (tens to hundreds of nanoamperes per square meter). Launched continually during intervals of geomagnetic activity, these reconnection outflow flux fronts convert ~10 to 100 gigawatts per square Earth radius of power, consistent with local magnetic flux transport, and a few times 10(15) joules of magnetic energy, consistent with global magnetotail flux reduction. PMID:24072917

Angelopoulos, V; Runov, A; Zhou, X-Z; Turner, D L; Kiehas, S A; Li, S-S; Shinohara, I

2013-09-27

32

Wind energy conversion system  

DOEpatents

The wind energy conversion system includes a wind machine having a propeller connected to a generator of electric power, the propeller rotating the generator in response to force of an incident wind. The generator converts the power of the wind to electric power for use by an electric load. Circuitry for varying the duty factor of the generator output power is connected between the generator and the load to thereby alter a loading of the generator and the propeller by the electric load. Wind speed is sensed electro-optically to provide data of wind speed upwind of the propeller, to thereby permit tip speed ratio circuitry to operate the power control circuitry and thereby optimize the tip speed ratio by varying the loading of the propeller. Accordingly, the efficiency of the wind energy conversion system is maximized.

Longrigg, Paul (Golden, CO)

1987-01-01

33

Autonomous renewable energy conversion system  

Microsoft Academic Search

This paper briefly reviews the need for renewable power generation and describes a medium-power Autonomous Renewable Energy Conversion System (ARECS), integrating conversion of wind and solar energy sources. The objectives of the paper are to extract maximum power from the proposed wind energy conversion scheme and to transfer this power and the power derived by the photovoltaic system in a

Ventzislav Valtchev; Alex Van den Bossche; Jozef Ghijselen; Jan Melkebeek

2000-01-01

34

Energy conversion system  

DOEpatents

The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weathproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction and operational with a minimal power draw.

Murphy, L.M.

1985-09-16

35

Energy conversion system  

DOEpatents

The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weatherproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction, and operational with a minimal power draw.

Murphy, Lawrence M. (Lakewood, CO)

1987-01-01

36

Thermal Energy Conversion Branch  

NASA Technical Reports Server (NTRS)

The Thermal Energy Conversion Branch (5490) leads the way in designing, conducting, and implementing research for the newest thermal systems used in space applications at the NASA Glenn Research Center. Specifically some of the most advanced technologies developed in this branch can be broken down into four main areas: Dynamic Power Systems, Primary Solar Concentrators, Secondary Solar Concentrators, and Thermal Management. Work was performed in the Dynamic Power Systems area, specifically the Stirling Engine subdivision. Today, the main focus of the 5490 branch is free-piston Stirling cycle converters, Brayton cycle nuclear reactors, and heat rejection systems for long duration mission spacecraft. All space exploring devices need electricity to operate. In most space applications, heat energy from radioisotopes is converted to electrical power. The Radioisotope Thermoelectric Generator (RTG) already supplies electricity for missions such as the Cassini Spacecraft. The focus of today's Stirling research at GRC is aimed at creating an engine that can replace the RTG. The primary appeal of the Stirling engine is its high system efficiency. Because it is so efficient, the Stirling engine will significantly reduce the plutonium fuel mission requirements compared to the RTG. Stirling is also being considered for missions such as the lunar/Mars bases and rovers. This project has focused largely on Stirling Engines of all types, particularly the fluidyne liquid piston engine. The fluidyne was developed by Colin D. West. This engine uses the same concepts found in any type of Stirling engine, with the exception of missing mechanical components. All the working components are fluid. One goal was to develop and demonstrate a working Stirling Fluidyne Engine at the 2nd Annual International Energy Conversion Engineering Conference in Providence, Rhode Island.

Bielozer, Matthew C.; Schreiber, Jeffrey, G.; Wilson, Scott D.

2004-01-01

37

Wind energy conversion system  

SciTech Connect

This patent describes a wind energy conversion system comprising: a propeller rotatable by force of wind; a generator of electricity mechanically coupled to the propeller for converting power of the wind to electric power for use by an electric load; means coupled between the generator and the electric load for varying the electric power drawn by the electric load to alter the electric loading of the generator; means for electro-optically sensing the speed of the wind at a location upwind from the propeller; and means coupled between the sensing means and the power varying means for operating the power varying means to adjust the electric load of the generator in accordance with a sensed value of wind speed to thereby obtain a desired ratio of wind speed to the speed of a tip of a blade of the propeller.

Longrigg, P.

1987-03-17

38

Energy conversion apparatus  

SciTech Connect

This patent describes an energy conversion apparatus. It comprises a base housing, the base housing including a cooling fluid bath contained therewithin, the base housing including a top wall; a first heating conduit mounted to and projecting into the base housing through the top wall; a second cooling conduit mounted to the top wall projecting therethrough; a lower pulley rotatably mounted within the base housing, a platform spaced above the base housing, an upper pulley, an endless belt wound about the upper and lower pulleys directed through the first conduit and the second conduit; a plurality of equally spaced fluid filled balloons mounted upon the endless belt; heating means for effecting heating interiorly of the first conduit for effecting vaporizing of the fluid within the balloons when directed therethrough to effect ascent of the balloons through the first conduit and descent of the balloons through the second conduit.

Evanger, J.A.; Ellison, R.A.

1992-06-30

39

Demonstrating Energy Conversion with Piezoelectric Crystals and a Paddle Fan  

ERIC Educational Resources Information Center

A simple energy conversion system--particularly, the conversion of mechanical energy into electrical energy by using shaker flashlights--has recently been presented. This system uses hand generators, consisting of a magnet in a tube with a coil wrapped around it, and acts as an ac source when the magnet passes back and forth through the coil.…

Rakbamrung, Prissana; Putson, Chatchai; Muensit, Nantakan

2014-01-01

40

Direct electric energy conversion system for energy conversion from marine currents  

Microsoft Academic Search

Direct electric energy conversion without input power regulating system or gearboxes may offer a simpler and thus low cost way of converting the energy of moving water. The pro- posed electrical system consists of a permanent magnetized direct drive generator, a rectifica- tion step, transmission, an inverter, a transformer, and a grid connection. This paper focuses on the generator, and

M Leijonand; K Nilsson

2007-01-01

41

Electrofluid dynamics energy conversion research  

Microsoft Academic Search

Electrofluid Dynamics (EFD) is a method of direct energy conversion in which the energy contained in a flowing gas is converted directly into electrical energy. This is generally accomplished by seeding the flowing gas with unipolar charged ions produced by a corona discharge from a sharp grounded electrode. The unipolar ions typically are deposited on particles usually produced by condensation

E. F. Fretter; R. W. Griffith

1975-01-01

42

Ocean Thermal Energy Conversion (OTEC)  

NASA Technical Reports Server (NTRS)

Energy Research and Development Administration research progress in Ocean Thermal Energy Conversion (OTEC) is outlined. The development program is being focused on cost effective heat exchangers; ammonia is generally used as the heat exchange fluid. Projected costs for energy production by OTEC vary between $1000 to $1700 per kW.

Lavi, A.

1977-01-01

43

Energy conversion engine  

Microsoft Academic Search

Fuelless means of obtaining energy comprising: (A description is given of a) a cellular conveyor means for carrying air at atmospheric pressure down to great water depths and converting it to stored energy in the form of compressed air; (B) open bottom bell type container for capturing the compressed air; and (C) means for converting the stored energy to pratical

Grande

1980-01-01

44

Energy conversion and storage program  

NASA Astrophysics Data System (ADS)

The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: (1) production of new synthetic fuels; (2) development of high-performance rechargeable batteries and fuel cells; (3) development of advanced thermochemical processes for energy conversion; (4) characterization of complex chemical processes; and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

Cairns, E. J.

1992-03-01

45

Energy Conversion and Storage Program  

SciTech Connect

The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

Cairns, E.J.

1992-03-01

46

Solar energy conversion.  

SciTech Connect

The Sun provides Earth with a staggering amount of energy - enough to power the great oceanic and atmospheric currents, the cycle of evaporation and condensation that brings fresh water inland and drives river flow, and the typhoons, hurricanes, and tornadoes that so easily destroy the natural and built landscape. The San Francisco earthquake of 1906, with magnitude 7.8, released an estimated 10{sup 17} joules of energy, the amount the Sun delivers to Earth in one second. Earth's ultimate recoverable resource of oil, estimated at 3 trillion barrels, contains 1.7 x 10{sup 22} joules of energy, which the Sun supplies to Earth in 1.5 days. The amount of energy humans use annually, about 4.6 x 10{sup 20} joules, is delivered to Earth by the Sun in one hour. The enormous power that the Sun continuously delivers to Earth, 1.2 x 10{sup 5} terawatts, dwarfs every other energy source, renewable or nonrenewable. It dramatically exceeds the rate at which human civilization produces and uses energy, currently about 13 TW.

Crabtree, G. W.; Lewis, N. S.; Materials Science Division; Cal Tech

2007-03-01

47

Energy conversion in the coronal plasma  

NASA Technical Reports Server (NTRS)

Solar and stellar X-ray emission are the observed waste products of the interplay between magnetic fields and the motion of stellar plasma. Theoretical understanding of the process of coronal heating is of utmost importance, since the high temperature is what defines the corona in the first place. Most of the research described deals with the aspects of the several rivalling theories for coronal heating. The rest of the papers deal with processes of energy conversion related to flares.

Martens, P. C. H.

1986-01-01

48

Review of betavoltaic energy conversion  

NASA Technical Reports Server (NTRS)

Betavoltaic energy conversion refers to the generation of power by coupling a beta source to a semiconductor junction device. The theory of betavoltaic energy conversion and some past studies of the subject are briefly reviewed. Calculations of limiting efficiencies for semiconductor cells versus bandgap are presented along with specific studies for Pm-147 and Ni-63 fueled devices. The approach used for fabricating Pm-147 fueled batteries by the author in the early 1970's is reviewed. Finally, the potential performance of advanced betavoltaic power sources is considered.

Olsen, Larry C.

1993-01-01

49

Energy Conversion Engineering. [Textbook  

Microsoft Academic Search

This book is a teaching text, directed toward students at the senior year in engineering or the physical sciences. The information presented is directed toward providing some of the analytical tools that will allow many of the arguments surrounding energy policy to be reduced to numerical values. The book provides a discussion of the laws of thermodynamics, chemical equilibrium, chemical

Bailie

1978-01-01

50

Demonstrating Energy Conversion with Piezoelectric Crystals and a Paddle Fan  

NASA Astrophysics Data System (ADS)

A simple energy conversion system—particularly, the conversion of mechanical energy into electrical energy by using shaker flashlights—has recently been presented. This system uses hand generators, consisting of a magnet in a tube with a coil wrapped around it, and acts as an ac source when the magnet passes back and forth through the coil. Additionally, this system includes an LED, a capacitor, a switch, and a full-wave bridge rectifier. We were inspired by this work to design a simpler demonstrator made for teaching energy conversion concepts to science students using piezoelectric material.

Rakbamrung, Prissana; Putson, Chatchai; Muensit, Nantakan

2014-02-01

51

Closed loop energy conversion system  

Microsoft Academic Search

An energy conversion system is disclosed that utilizes a gravity flow of water from a high elevation to sea level utilizing gravity to provide large pressure gradients in pipe lines as large quantities of water move from a high elevation at low pressure to low elevations at high pressure and then move under controlled conditions to low atmosphere pressure to

Botts

1981-01-01

52

Turbulence and energy conversion research  

SciTech Connect

This report examines the role of fluid mechanics research (particularly turbulence research) in improving energy conversion systems. In this report two of the listed application areas are selected as examples: fluidization and cavitation. Research needs in general, and research possibilities for ECUT in particular, are examined.

Hutchinson, R.A.

1985-07-01

53

Photochemical conversion of solar energy.  

PubMed

Energy is the most important issue of the 21st century. About 85% of our energy comes from fossil fuels, a finite resource unevenly distributed beneath the Earth's surface. Reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects such as pollution that threatens human health and greenhouse gases associated with global warming. Prompt global action to solve the energy crisis is therefore needed. To pursue such an action, we are urged to save energy and to use energy in more efficient ways, but we are also forced to find alternative energy sources, the most convenient of which is solar energy for several reasons. The sun continuously provides the Earth with a huge amount of energy, fairly distributed all over the world. Its enormous potential as a clean, abundant, and economical energy source, however, cannot be exploited unless it is converted into useful forms of energy. This Review starts with a brief description of the mechanism at the basis of the natural photosynthesis and, then, reports the results obtained so far in the field of photochemical conversion of solar energy. The "grand challenge" for chemists is to find a convenient means for artificial conversion of solar energy into fuels. If chemists succeed to create an artificial photosynthetic process, "... life and civilization will continue as long as the sun shines!", as the Italian scientist Giacomo Ciamician forecast almost one hundred years ago. PMID:18605661

Balzani, Vincenzo; Credi, Alberto; Venturi, Margherita

2008-01-01

54

Energy conversion in photosynthesis  

NASA Astrophysics Data System (ADS)

Photosystem II (PSII) uses light energy to split water into protons, electrons and O2 [1]. In this reaction, Nature has solved the difficult chemical problem of efficient four-electron oxidation of water to yield O2 without significant side reactions. In order to use Nature's solution for the design of materials that split water for solar fuel production, it is important to understand the mechanism of the reaction. The X ray crystal structures of cyanobacterial PSII provide information on the structure of the Mn and Ca ions, the redox-active tyrosine called YZ, and the surrounding amino acids that comprise the O2 evolving complex (OEC) [2,3]. We have used computational studies used to refine the structure of the OEC to obtain a complete structural model of the OEC that is in agreement with spectroscopic data [4,5]. The structure of the OEC and the mechanism of water oxidation by PSII will be discussed in the light of biophysical and computational studies, inorganic chemistry and X-ray crystallographic information. [4pt] [1] J.P. McEvoy and G.W. Brudvig, Chem. Rev. (2006) 106, 4455-4483. [0pt] [2] K.N. Ferreira et al., Science (2004) 303, 1831-1838. [0pt] [3] B. Loll et al., Nature (2006) 438, 1040-1044. [0pt] [4] E.M. Sproviero et al., J. Am. Chem. Soc. (2008) 130, 6728-6730. [0pt] [5] E.M. Sproviero et al., J. Am. Chem. Soc. (2008) 130, 3428-3442.

Brudvig, Gary

2011-03-01

55

Electrochemical Processes in Energy Conversion and Storage  

Microsoft Academic Search

At present generation of electrical energy is mainly based on the conversion of fossil fuels such as coal, oil and natural gas within thermal cycle power plants. Although the overall conversion efficiency of thermal power plants was significantly increased, electrochemical energy conversion processes have the potential to further optimize conversion efficiency. Especially high temperature fuel cells, based on solid oxide-

Rainer Bussar; Ulrich Stimming

56

Direct solar energy conversion at sea  

Microsoft Academic Search

Hydrogen production and delivery from direct solar energy conversion facilities located at sea is treated, assuming the use of a heat engine\\/electricity generation\\/water electrolysis system. The concept of ocean energy is discussed, noting the distinction between direct and indirect solar energy conversion at sea, and direct solar energy conversion is considered within the framework of the seaward advancement of industrial

W. J. D. Escher; T. Ohta

1979-01-01

57

Materials for thermoelectric energy conversion  

NASA Technical Reports Server (NTRS)

The field of thermoelectric energy conversion is reviewed from both a theoretical and an experimental standpoint. The basic theory is introduced and the thermodynamic and solid state views are compared. An overview of the development of thermoelectric materials is presented with particular emphasis being placed on the most recent developments in high-temperature semiconductors. A number of possible device applications are discussed and the successful use and suitability of these devices for space power is manifest.

Wood, C.

1988-01-01

58

Semiconductor Nanowires and Nanotubes for Energy Conversion  

E-print Network

Engineering nanoscale phonon and photon transport for direct energy conversion.Energy Conversion by Melissa Anne Fardy Doctor of Philosophy in Chemistry with a Designated Emphasis in Nanoscale Science and Engineering

Fardy, Melissa Anne

2010-01-01

59

Pyroelectric energy conversion: optimization principles.  

PubMed

In the framework of microgenerators, we present in this paper the key points for energy harvesting from temperature using ferroelectric materials. Thermoelectric devices profit from temperature spatial gradients, whereas ferroelectric materials require temporal fluctuation of temperature, thus leading to different applications targets. Ferroelectric materials may harvest perfectly the available thermal energy whatever the materials properties (limited by Carnot conversion efficiency) whereas thermoelectric material's efficiency is limited by materials properties (ZT figure of merit). However, it is shown that the necessary electric fields for Carnot cycles are far beyond the breakdown limit of bulk ferroelectric materials. Thin films may be an excellent solution for rising up to ultra-high electric fields and outstanding efficiency. Different thermodynamic cycles are presented in the paper: principles, advantages, and drawbacks. Using the Carnot cycle, the harvested energy would be independent of materials properties. However, using more realistic cycles, the energy conversion effectiveness remains dependent on the materials properties as discussed in the paper. A particular coupling factor is defined to quantify and check the effectiveness of pyroelectric energy harvesting. It is defined similarly to an electromechanical coupling factor as k2=p2theta0/(epsilontheta33cE), where p, theta0, epsilontheta33, cE are pyroelectric coefficient, maximum working temperature, dielectric permittivity, and specific heat, respectively. The importance of the electrothermal coupling factor is shown and discussed as an energy harvesting figure of merit. It gives the effectiveness of all techniques of energy harvesting (except the Carnot cycle). It is finally shown that we could reach very high efficiency using 1110.75Pb(Mg1/3Nb2/3)-0.25PbTiO3 single crystals and synchronized switch harvesting on inductor (almost 50% of Carnot efficiency). Finally, practical implementation key points of pyroelectric energy harvesting are presented showing that the different thermodynamic cycles are feasible and potentially effective, even compared to thermoelectric devices. PMID:18407845

Sebald, Gael; Lefeuvre, Elie; Guyomar, Daniel

2008-03-01

60

Radiation energy conversion in space  

NASA Technical Reports Server (NTRS)

Topics discussed at the third NASA conference on radiant energy conversion are reviewed. The unconcentrated-photovoltaic-generation version of a solar power satellite is described, noting that it will consist of a 21.3 x 5.3-sq-km silicon-solar-cell array expected to provide 17 Gw of electrical power, with 1 km in diam transmitters oriented to beam 2.45 GHz microwave power to two receiving/rectifying 'rectennas' on earth. The Solares space-energy-system concept, designed for providing a large fraction of the world's energy needs at costs comparable to those of future coal/nuclear alternative, is considered, as are subsystems for improving the economics of the solar power satellite. A concept proposing the use of relativistic-electron-storage rings for electron-beam energy transmission and storage, and a report on the production of a high temperature plasma with concentrated solar radiation are taken into account. Laser-conversion systems, including the direct-solar-pumped space laser, and the telec-powered spacecraft, are discussed.

Billman, K. W.

1979-01-01

61

Ocean thermal-energy conversion  

NASA Astrophysics Data System (ADS)

The principles underlying ocean thermal-energy conversion (OTEC) are reviewed, and a schematic layout of a system is included. The two systems currently under study, the open system and the closed system, are described. The prospect now, it is noted, is that OTEC plants will not be commercially viable on a widespread basis, even in the tropics. This is especially true of the large-scale plants that have been envisioned. A strong possibility is seen, however, that smaller plants, generating about 40 megawatts of electrical power, can survive commercially. The following conditions would favor their success: placement on land rather than at sea; placement in areas (such as islands) where alternative energy supplies are at a premium; and designing the plant to operate in conjunction with either an aquaculture or a desalination plant.

Ford, G.; Niblett, C.; Walker, L.

1983-03-01

62

Ocean Thermal Energy Conversion LUIS A. VEGA  

E-print Network

Ocean Thermal Energy Conversion LUIS A. VEGA Hawaii Natural Energy Institute, School of Ocean depths of 20 m (surface water) and 1,000 m. OTEC Ocean Thermal Energy Conversion, the process of converting the ocean thermal energy into electricity. OTEC transfer function The relationship between

63

Clean Fossil Energy Conversion Processes  

NASA Astrophysics Data System (ADS)

Absolute and per-capita energy consumption is bound to increase globally, leading to a projected increase in energy requirements of 50% by 2020. The primary source for providing a majority of the energy will continue to be fossil fuels. However, an array of enabling technologies needs to be proven for the realization of a zero emission power, fuel or chemical plants in the near future. Opportunities to develop new processes, driven by the regulatory requirements for the reduction or elimination of gaseous and particulate pollutant abound. This presentation describes the chemistry, reaction mechanisms, reactor design, system engineering, economics, and regulations that surround the utilization of clean coal energy. The presentation will cover the salient features of the fundamental and process aspects of the clean coal technologies in practice as well as in development. These technologies include those for the cleaning of SO2, H2S, NOx, and heavy metals, and separation of CO2 from the flue gas or the syngas. Further, new combustion and gasification processes based on the chemical looping concepts will be illustrated in the context of the looping particle design, process heat integration, energy conversion efficiency, and economics.

Fan, L.-S.

2007-03-01

64

The upper limit to solar energy conversion  

Microsoft Academic Search

Petela carried out research to determine the maximum ideal theoretical work output obtainable from BR independent of any conversion device. However, omnicolor conversion is considered by many to be the ideal theoretical process for solar energy conversion. Petela's result for blackbody radiation (BR) exergy is often thought to be of little importance because it appears to neglect fundamental theoretical issues

Sean E. Wright; David S. Scott; James B. Haddow; Marc A. Rosen

2000-01-01

65

Thermophotovoltaic Energy Conversion Development Program  

NASA Technical Reports Server (NTRS)

Completely integrated thermophotovoltaic (TPV) power sources in the range of 100 to 500 watts are being developed. The technical approach taken in this project focuses on optimizing the integrated performance of the primary subsystems in order to yield high energy conversion efficiency and cost effectiveness. An important aspect of the approach is the use of a narrow band fibrous emitter radiating to a bandgap matched photovoltaic array to minimize thermal and optical recuperation requirements, as well as the non-recoverable heat losses. For the prototype system, fibrous ytterbia emitters radiating in a narrow band centered at 980 nm are matched with high efficiency silicon photoconverters. The integrated system includes a dielectric stack filter for optical energy recovery and a ceramic recuperator for thermal energy recovery. The prototype TPV system uses a rapid mix distributed fuel delivery system with controlled feeding of the fuel and heated air into a flame at the surface of the emitter. This makes it possible to operate at air preheat temperatures well above the auto-ignition temperature of the fuel thereby substantially increasing the system efficiency. The system has been operated with air preheat temperatures up to 1367 K and has produced a uniform narrow band radiation over the surface of the emitter with this approach. The design of the system is described and test data for the system and some of the key components are presented. The results from a system model, which show the impact of various parameters on system performance, are also discussed.

Shukla, Kailash; Doyle, Edward; Becker, Frederick

1998-01-01

66

Revitalizing Undergraduate Electric Energy Conversion Education  

Microsoft Academic Search

The content of the core curriculum course in energy conversion for electrical engineers has been incrementally updated over the last 50 years. However, recent advances in micro and nano- science have created many new devices and analysis methods. Consequently, there is an increas- ing gap between the classical topics covered in existing textbooks and course plans on energy conversion compared

Roy A. McCann

67

Magnetic energy flow in the solar wind.  

NASA Technical Reports Server (NTRS)

Discussion of the effect of rotation (tangential flow) of the solar wind on the conclusions of Whang (1971) suggesting an increase in the solar wind velocity due to the conversion of magnetic energy to kinetic energy. It is shown that the effect of the rotation of the sun on the magnetic energy flow results in most of the magnetic energy being transported by magnetic shear stress near the sun.

Modisette, J. L.

1972-01-01

68

High temperature thermoelectric energy conversion  

NASA Technical Reports Server (NTRS)

The theory and current status of materials research for high-temperature thermoelectric energy conversion are reviewed. Semiconductors are shown to be the preferred class of materials for this application. Optimization of the figure of merit of both broadband and narrow-band semiconductors is discussed as a function of temperature. Phonon scattering mechanisms are discussed, and basic material guidelines are given for reduction of thermal conductivity. Two general classes of materials show promise for high temperature figure of merit (Z) values, namely the rare earth chalcogenides and the boron-rich borides. The electronic transport properties of the rare earth chalcogenides are explicable on the basis of degenerate or partially degenerate n-type semiconductors. Boron and boron-rich borides exhibit p-type hopping conductivity, with detailed explanations proposed for the transport differing from compound to compound. Some discussion is presented on the reasons for the low thermal conductivities in these materials. Also, ZTs greater than one appear to have been realized at high temperature in many of these compounds.

Wood, Charles

1987-01-01

69

Recycling of wasted energy : thermal to electrical energy conversion  

E-print Network

Energy Conversion by Hyuck Lim Doctor of Philosophy in Materials Science and EngineeringEnergy Conversion A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Materials Science and Engineering

Lim, Hyuck

2011-01-01

70

Assessment of ocean thermal energy conversion  

E-print Network

Ocean thermal energy conversion (OTEC) is a promising renewable energy technology to generate electricity and has other applications such as production of freshwater, seawater air-conditioning, marine culture and chilled-soil ...

Muralidharan, Shylesh

2012-01-01

71

Neutrino conversions in solar random magnetic fields  

NASA Astrophysics Data System (ADS)

We consider the effect of a random magnetic field in the convective zone of the Sun superimposed to a regular magnetic field on resonant neutrino spin-flavor oscillations. We argue for the existence of a field of strongly chaotic nature at the bottom of the convective zone. In contrast to previous attempts we employ a model motivated regular magnetic field profile: it is a static field solution to the solar equilibrium hydro-magnetic equations. These solutions have been known for a long time in the literature. We show for the first time that in addition they are twisting solutions. In this scenario electron antineutrinos are produced through cascades like ?eL-->??L-- >?~eR, The detection of ?~eR at Earth would be a long-awaited signature of the Majorana nature of the neutrino. The expected signals in the different experiments (SK, GALLEX-SAGE, Homestake) are obtained as a function of the level of noise, regular magnetic field and neutrino mixing parameters. Previous results obtained for small mixing and ad-hoc regular magnetic profiles are reobtained. We confirm the strong suppression for a large part of the parameter space of the ?~eR-flux for high energy boron neutrinos in agreement with present data of the SK experiment. We find that MSW (Mikheyev-Smirnov-Wolfenstein) regions (?m2~=10-5 eV2, both small and large mixing solutions) are stable up to very large levels of noise (P=0.7-0.8) but they are acceptable from the point of view of antineutrino production only for moderate levels of noise (P~=0.95). For strong noise and a reasonable regular magnetic field, any parameter region (?m2, sin 2 2?) is excluded. As a consequence, we are allowed to reverse the problem and to put limits on the r.m.s. field strength and transition magnetic moments by demanding a particle physics solution to the SNP in this scenario.

Semikoz, V. B.; Torrente-Lujan, E.

1999-09-01

72

Proceedings of the 25th Intersociety Energy Conversion Engineering Conference  

Microsoft Academic Search

This book contains the proceedings of a conference on energy conversion engineering. The papers presented include: Development of a fuel cell power source for bus; System applications of tubular solid oxide fuel cells; and Phenomenology of forces acting between magnets and superconductors.

P. A. Nelson; W. W. Schertz; R. H. Till

1990-01-01

73

Power electronics in wind energy conversion systems  

Microsoft Academic Search

This paper presents a brief review of the power electronics techniques used in wind energy conversion systems. Utilization of power electronics converters enables conversion of the generated power from any form to another and thus control the operation quality and obtain capture optimization. Attention is paid to power converters selection and design to satisfy good matching between generator type and

FAEKA M. H. KHATER

1996-01-01

74

Energy conversion & storage program. 1994 annual report  

SciTech Connect

The Energy Conversion and Storage Program investigates state-of-the-art electrochemistry, chemistry, and materials science technologies for: (1) development of high-performance rechargeable batteries and fuel cells; (2) development of high-efficiency thermochemical processes for energy conversion; (3) characterization of complex chemical processes and chemical species; (4) study and application of novel materials for energy conversion and transmission. Research projects focus on transport process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

Cairns, E.J.

1995-04-01

75

Energy Conversion & Storage Program, 1993 annual report  

SciTech Connect

The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: production of new synthetic fuels; development of high-performance rechargeable batteries and fuel cells; development of high-efficiency thermochemical processes for energy conversion; characterization of complex chemical processes and chemical species; and the study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

Cairns, E.J.

1994-06-01

76

Conversion of radiant light energy in photobioreactors  

Microsoft Academic Search

The conversion of radiant light energy into chemical affinity by microorganisms in photobioreactors is examined. The kinetics of entropy production in the system is theoretically established from entropy and energy balances for the material and photonic phases in the reactor. A negative chemical affinity term compensated for by a radiant energy term at a higher level of energy characterizes photosynthetic

J. F. Cornet; C. G. Dussap; J. B. Gros

1994-01-01

77

Energy Conversion in Natural and Artificial Photosynthesis  

PubMed Central

Summary Modern civilization is dependent upon fossil fuels, a nonrenewable energy source originally provided by the storage of solar energy. Fossil fuel dependence has severe consequences including energy security issues and greenhouse gas emissions. The consequences of fossil fuel dependence could be avoided by fuel-producing artificial systems that mimic natural photosynthesis, directly converting solar energy to fuel. This review describes the three key components of solar energy conversion in photosynthesis: light harvesting, charge separation, and catalysis. These processes are compared in natural and artificial systems. Such a comparison can assist in understanding the general principles of photosynthesis and in developing working devices including photoelectrochemical cells for solar energy conversion. PMID:20534342

McConnell, Iain; Li, Gonghu; Brudvig, Gary W.

2010-01-01

78

Experimental and Analytical Studies on Pyroelectric Waste Heat Energy Conversion  

E-print Network

21st Intersociety Energy Conversion Engineering Conference,Energy Conversion by Felix Lee Master of Science in Mechanical EngineeringEnergy Conversion A thesis submitted in partial satisfaction of the requirements for the degree Master of Science in Mechanical Engineering

Lee, Felix

2012-01-01

79

Micro Electret Energy Harvesting Device with Analogue Impedance Conversion Circuit  

E-print Network

Micro Electret Energy Harvesting Device with Analogue Impedance Conversion Circuit Yuji Suzuki1 using a low-power-consumption impedance conversion circuit. Key words: Energy harvesting, Electret, CYTOP, Parylene spring, Impedance conversion 1. INTRODUCTION Energy harvesting from environmental

Kasagi, Nobuhide

80

NAVFAC Ocean Thermal Energy Conversion (OTEC) Project  

E-print Network

NAVFAC Ocean Thermal Energy Conversion (OTEC) Project Contract Number N62583-09-C-0083 CDRL A014 Engineering Command Naval Facilities Engineering Service Center (NFESC) 1100 23rd Avenue Port Hueneme, CA

81

Second NASA Conference on Laser Energy Conversion  

NASA Technical Reports Server (NTRS)

The possible transmission of high power laser beams over long distances and their conversion to thrust, electricity, or other useful forms of energy is considered. Specific topics discussed include: laser induced chemistry; developments in photovoltaics, including modification of the Schottky barrier devices and generation of high voltage emf'sby laser radiation of piezoelectric ceramics; the thermo electronic laser energy converter and the laser plasmadynamics converters; harmonic conversion of infrared laser radiation in molecular gases; and photon engines.

Billman, K. W. (editor)

1976-01-01

82

Thermionic Energy Conversion (TEC) topping thermoelectrics  

NASA Technical Reports Server (NTRS)

Performance expectations for thermionic and thermoelectric energy conversion systems are reviewed. It is noted that internal radiation effects diminish thermoelectric figures of merit significantly at 1000 K and substantially at 2000 K; the effective thermal conductivity contribution of intrathermoelectric radiative dissipation increases with the third power of temperature. It is argued that a consideration of thermoelectric power generation with high temperature heat sources should include utilization of thermionic energy conversion (TEC) topping thermoelectrics. However TEC alone or TEC topping more efficient conversion systems like steam or gas turbines, combined cycles, or Stirling engines would be more desirable generally.

Morris, J. F.

1981-01-01

83

Chemistry of energy conversion and storage.  

PubMed

Energy is a big issue in our society, fueled by growing awareness of the finite resources of liquid fossil fuels and the noticeable changes in our climate resulting from its consumption. The general consensus is that there should be a well-considered roadmap towards a future energy scenario, with the replacement of fossil energy by renewable energies as the final goal. This "Chemistry of Energy Conversion and Storage" issue contains papers dealing with the chemistry behind renewable energies. PMID:22407997

Su, Dang Sheng

2012-03-12

84

Electromagnetic wave energy conversion research  

NASA Technical Reports Server (NTRS)

Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.

Bailey, R. L.; Callahan, P. S.

1975-01-01

85

SPS Energy Conversion Power Management Workshop  

NASA Technical Reports Server (NTRS)

Energy technology concerning photovoltaic conversion, solar thermal conversion systems, and electrical power distribution processing is discussed. The manufacturing processes involving solar cells and solar array production are summarized. Resource issues concerning gallium arsenides and silicon alternatives are reported. Collector structures for solar construction are described and estimates in their service life, failure rates, and capabilities are presented. Theories of advanced thermal power cycles are summarized. Power distribution system configurations and processing components are presented.

1980-01-01

86

Neutrino Conversions in Solar Random Magnetic Fields  

E-print Network

We consider the effect of a random magnetic field in the convective zone of the Sun superimposed to a regular magnetic field on resonant neutrino spin-flavour oscillations. We argue for the existence of a field of strongly chaotic nature at the bottom of the convective zone. In contrast to previous attempts we employ in addition a model motivated regular twisting magnetic field profile. In this scenario electron antineutrinos are produced through cascades like $\

V. B Semikoz; E. Torrente-Lujan

1998-09-16

87

Biomass energy conversion as an alternate energy source  

Microsoft Academic Search

A study in the US indicates that 327 t or 44% of the biomass produced in the US other than agricultural and forestry products would be available for conversion into energy but would yield only 1.9% of the total energy currently used annually. The major advantages and disadvantages of using biomass material for energy conversion are given. Food processing wastes,

N. Goodman; D. Pimentel

2009-01-01

88

Modulated reconnection rate and energy conversion at the magnetopause under steady IMF conditions  

Microsoft Academic Search

We use the multi-spacecraft mission Cluster to make observational estimates of the local energy conversion across the dayside high-latitude magnetopause. The energy conversion is estimated during eleven complete magnetopause crossings under steady south-dawnward interplanetary magnetic field (IMF). We describe a new method to determine the reconnection rate from the magnitude of the local energy conversion. The reconnection rate as well

L. Rosenqvist; A. Vaivads; A. Retinò; T. Phan; H. J. Opgenoorth; I. Dandouras; S. Buchert

2008-01-01

89

Last roadblocks to new energy conversion projects  

Microsoft Academic Search

Aspects of engineering and construction capabilities as related to ; improving energy production are reviewed. It is noted that a potential roadblock ; to new energy conversion projects is the improper allocation of engineering and ; construction manpower and supporting equipment. Current conditions of equipment ; materials availability are reviewed along with the status of engineering and ; skilled labor

Lattin; C. P. Jr

1973-01-01

90

Iron disulfide for solar energy conversion  

Microsoft Academic Search

Pyrite (Eg = 0.95 eV) is being developed as a solar energy material due to its environmental compatibility and its very high light absorption coefficient. A compilation of material, electronic and interfacial chemical properties is presented, which is considered relevant for quantum energy conversion. In spite of intricate problems existing within material chemistry, high quantum efficiencies for photocurrent generation (Eta

A ENNAOUI; S FIECHTER; C PETTENKOFER; N ALONSOVANTE; K BUKER; M BRONOLD; C HOPFNER; H TRIBUTSCH

1993-01-01

91

Ocean Thermal Energy Conversion Mostly about USA  

E-print Network

Ocean Thermal Energy Conversion History Mostly about USA 1980's to 1990's and bias towards Vega CWP Installation failure · Historical slide from Inventor is indicative of multiple engineering or other energy carriers to be delivered to shore... 13luisvega@hawaii.edu #12;US Federal Government OTEC

92

Energy Forms, States and Conversions  

NSDL National Science Digital Library

Students participate in many demonstrations during the first day of this lesson to learn basic concepts related to the forms and states of energy. This knowledge is then applied the second day as students assess various everyday objects to determine what forms of energy are transformed to accomplish the object's intended task. Students use block diagrams to illustrate the form and state of energy flowing into and out of the process.

Office Of Educational Partnerships

93

Energy conversion & storage program. 1995 annual report  

SciTech Connect

The 1995 annual report discusses laboratory activities in the Energy Conversion and Storage (EC&S) Program. The report is divided into three categories: electrochemistry, chemical applications, and material applications. Research performed in each category during 1995 is described. Specific research topics relate to the development of high-performance rechargeable batteries and fuel cells, the development of high-efficiency thermochemical processes for energy conversion, the characterization of new chemical processes and complex chemical species, and the study and application of novel materials related to energy conversion and transmission. Research projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials and deposition technologies, and advanced methods of analysis.

Cairns, E.J.

1996-06-01

94

Harnessing surface plasmons for solar energy conversion  

NASA Technical Reports Server (NTRS)

NASA research on the feasibility of solar-energy conversion using surface plasmons is reviewed, with a focus on inelastic-tunnel-diode techniques for power extraction. The need for more efficient solar converters for planned space missions is indicated, and it is shown that a device with 50-percent efficiency could cost up to 40 times as much per sq cm as current Si cells and still be competitive. The parallel-processing approach using broadband carriers and tunable diodes is explained, and the physics of surface plasmons on metal surfaces is outlined. Technical problems being addressed include phase-matching sunlight to surface plasmons, minimizing ohmic losses and reradiation in energy transport, coupling into the tunnels by mode conversion, and gaining an understanding of the tunnel-diode energy-conversion process. Diagrams illustrating the design concepts are provided.

Anderson, L. M.

1983-01-01

95

A new wind energy conversion system  

NASA Technical Reports Server (NTRS)

It is presupposed that vertical axis wind energy machines will be superior to horizontal axis machines on a power output/cost basis and the design of a new wind energy machine is presented. The design employs conical cones with sharp lips and smooth surfaces to promote maximum drag and minimize skin friction. The cones are mounted on a vertical axis in such a way as to assist torque development. Storing wind energy as compressed air is thought to be optimal and reasons are: (1) the efficiency of compression is fairly high compared to the conversion of mechanical energy to electrical energy in storage batteries; (2) the release of stored energy through an air motor has high efficiency; and (3) design, construction, and maintenance of an all-mechanical system is usually simpler than for a mechanical to electrical conversion system.

Smetana, F. O.

1975-01-01

96

Optical isolator based on mode conversion in magnetic garnet films.  

PubMed

Calculations are presented describing a novel optical isolator which works by complete TE(0)-TM(0) mode conversion in magnetic garnet films caused by stress-induced optical anisotropy (50%) and by Faraday rotation (50%). These conversions take place along two different, perpendicular light paths in the same crystal that are connected by an integrated mirror. Possible tolerances of the film parameters are given so that a 30-dB isolation is still guaranteed. PMID:20490145

Hemme, H; Dötsch, H; Menzler, H P

1987-09-15

97

Energy conversion in piezoelectric superlattices  

Microsoft Academic Search

A superlattice is formed in a piezoelectric substrate by intervallic polarizing oppositely along one direction. Wave propagation in this structure is studied with plane-wave expansion method. The polariton behavior in the superlattice is obtained by solving Newton's equations of motion and Maxwell's equations simultaneously. Significant coupling between mechanical and electromagnetic energy occurs in the vicinity of the center of the

Yuan-Fang Chou; Ming-Yi Yang

2007-01-01

98

Lightning energy conversion using lasers  

Microsoft Academic Search

Potential energy sources are being investigated for the socioeconomic needs and increased power demand. Systems employing nuclear, thermal, hydro, solar, volcano, MHD, tidal and wind power generation techniques already exist. This work describes our attempt to utilize the off-planet lightning charge to store super electrolytic batteries or super capacitors. The electrostatic charge on clouds can be shifted to earth through

Nasrullah Khan; Norman Mariun

2000-01-01

99

Magnetic Materials Suitable for Fission Power Conversion in Space Missions  

NASA Technical Reports Server (NTRS)

Terrestrial fission reactors use combinations of shielding and distance to protect power conversion components from elevated temperature and radiation. Space mission systems are necessarily compact and must minimize shielding and distance to enhance system level efficiencies. Technology development efforts to support fission power generation scenarios for future space missions include studying the radiation tolerance of component materials. The fundamental principles of material magnetism are reviewed and used to interpret existing material radiation effects data for expected fission power conversion components for target space missions. Suitable materials for the Fission Power System (FPS) Project are available and guidelines are presented for bounding the elevated temperature/radiation tolerance envelope for candidate magnetic materials.

Bowman, Cheryl L.

2012-01-01

100

Energy Conversion: Nano Solar Cell  

NASA Astrophysics Data System (ADS)

Problems of fossil-fuel-induced climate change have sparked a demand for sustainable energy supply for all sectors of economy. Most laboratories continue to search for new materials and new technique to generate clean energy at affordable cost. Nanotechnology can play a major role in solving the energy problem. The prospect for solar energy using Si-based technology is not encouraging. Si photovoltaics can produce electricity at 20-30 c//kWhr with about 25% efficiency. Nanoparticles have a strong capacity to absorb light and generate more electrons for current as discovered in the recent work of organic and dye-sensitized cell. Using cheap preparation technique such as screen-printing and self-assembly growth, organic cells shows a strong potential for commercialization. Thin Films research group at National University Malaysia has been actively involved in these areas, and in this seminar, we will present a review works on nanomaterials for solar cells and particularly on hybrid organic solar cell based on ZnO nanorod arrays. The organic layer consisting of poly[2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEHPPV) and [6, 6]-phenyl C61-butyric acid 3-ethylthiophene ester (PCBE) was spin-coated on ZnO nanorod arrays. ZnO nanorod arrays were grown on FTO glass substrates which were pre-coated with ZnO nanoparticles using a low temperature chemical solution method. A gold electrode was used as the top contact. The device gave a short circuit current density of 2.49×10-4 mA/cm2 and an open circuit voltage of 0.45 V under illumination of a projector halogen light at 100 mW/cm2.

Yahaya, Muhammad; Yap, Chi Chin; Mat Salleh, Muhamad

2009-09-01

101

Power Quality Control and Design of Power Converter for Variable-Speed Wind Energy Conversion System with Permanent-Magnet Synchronous Generator  

PubMed Central

The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5?kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%. PMID:24453905

O?uz, Yüksel; Güney, ?rfan; Çal?k, Hüseyin

2013-01-01

102

Power quality control and design of power converter for variable-speed wind energy conversion system with permanent-magnet synchronous generator.  

PubMed

The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%. PMID:24453905

O?uz, Yüksel; Güney, ?rfan; Çal?k, Hüseyin

2013-01-01

103

Predictive control of wind energy conversion system  

Microsoft Academic Search

Grid connected wind energy conversion systems (WECS) present interesting control demands, due to the intrinsic nonlinear characteristics of windmills and electric generators. In this paper a predictive control strategy for doubly fed induction machine is proposed. The doubly fed induction machine is used in generating mode for large-scale grid-connected variable speed wind turbines. In order to control the active and

M. Bayat; H. Kazemi Karegar

2009-01-01

104

Ris Energy Report 2 Bioenergy conversion  

E-print Network

from applying a thermodynamic cycle in a combustion engine or a turbine. We can distinguish between the combustion gases pass through the engine or the tur- bine. Modern energy conversion machines are designed is the steam turbine with a separate combustor and boiler. A steam power plant, however, needs to be in MW

105

The power of thermionic energy conversion  

SciTech Connect

This article is a technology assessment of thermionic energy conversion. The topics of the article include current thermionic programs, application to planned military and civilian space missions, USA and former Soviet Union cooperation in thermionic developmental activities, the Topaz program, types of converters, emitter developments, demonstrating readiness, and ionization media developments.

Ramalingam, M.L. (UES Inc., Dayton, OH (United States)); Young, T.J. (Air Force Wright Lab., Wright-Patterson AFB, OH (United States). Aerospace Power Div.)

1993-09-01

106

Modernization of Biomass Energy Conversion Facilities  

Microsoft Academic Search

In this paper, the modernization studies of biomass energy conversion facilities are briefly reviewed. Here, the term biomass includes organic matter produced as a result of photosynthesis as well as municipal, industrial and animal waste material. The term modern biomass is generally used to describe the traditional biomass use through the efficient and clean combustion technologies and sustained supply of

A. Demirbas

2007-01-01

107

Advanced research directions in thermionic energy conversion  

Microsoft Academic Search

An overview is presented of plans for thermionic energy conversion research for the next decade. The primary focus is on space nuclear power applications in the 10 to 1000 kW range. In addition to refining the state of the art for the conventional ignited mode converter, there are more generic technologies which will be pursued for a wide range of

Elliot B. Kennel; Leonard H. Caveny

1989-01-01

108

Luminescent solar concentrators for energy conversion  

Microsoft Academic Search

Solar energy is the prominent renewable source of electricity if cheap methods will be designed for its concentration and\\u000a conversion. The geographical, seasonal and spectral distribution of the terrestrial solar energy are described. The concept\\u000a of non-tracking fluorescent concentrators and the mathematical background for collection and concentration of direct and diffuse\\u000a light are discussed. The single plate, multiple stacks and

Renata Reisfeld; Christian K. Jergensen

1982-01-01

109

Ocean thermal energy conversion: An overview  

NASA Astrophysics Data System (ADS)

Ocean thermal energy conversion, or OTEC is a technology that extracts power from the ocean's natural thermal gradient. This technology is being pursued by researchers from many nations; in the United States, OTEC research is funded by the U.S. Department of Energy's Ocean Energy Technology program. The program's goal is to develop the technology so that industry can make a competent assessment of its potential; either as an alternative or as a supplement to conventional energy sources. Federally funded research in components and systems will help OTEC to the threshold of commercialization. An overview of the OTEC technology is provided.

1989-11-01

110

Constraining primordial magnetic fields by CMB photon-graviton conversion  

NASA Astrophysics Data System (ADS)

We revisit the method of using the photon-graviton conversion mechanism in the presence of the external magnetic field to probe small-scale primordial magnetic fields that may exist between the last scattering surface and the present. Specifically, we investigate impacts on the conversion efficiency due to the presence of matter, including the plasma collective effect and the atomic polarizability. In general, these effects tend to reduce the conversion probability. Under this more realistic picture and based on the precision of Cosmic Background Explorer’s measurement of the cosmic microwave background (CMB) blackbody spectrum, we find an upper bound for the primordial magnetic field strength, B?30G, at the time of recombination. Although at present the bound based on the photon-graviton conversion mechanism is not as tight as that obtained by the direct use of CMB temperature anisotropy, it nevertheless provides an important independent constraint on primordial magnetic fields and at epochs in addition to the recombination. The bound can be significantly improved if the CMB blackbody spectrum measurement becomes more precise in future experiments such as Primordial Inflation Explorer.

Chen, Pisin; Suyama, Teruaki

2013-12-01

111

Novel Nuclear Powered Photocatalytic Energy Conversion  

SciTech Connect

The University of Massachusetts Lowell Radiation Laboratory (UMLRL) is involved in a comprehensive project to investigate a unique radiation sensing and energy conversion technology with applications for in-situ monitoring of spent nuclear fuel (SNF) during cask transport and storage. The technology makes use of the gamma photons emitted from the SNF as an inherent power source for driving a GPS-class transceiver that has the ability to verify the position and contents of the SNF cask. The power conversion process, which converts the gamma photon energy into electrical power, is based on a variation of the successful dye-sensitized solar cell (DSSC) design developed by Konarka Technologies, Inc. (KTI). In particular, the focus of the current research is to make direct use of the high-energy gamma photons emitted from SNF, coupled with a scintillator material to convert some of the incident gamma photons into photons having wavelengths within the visible region of the electromagnetic spectrum. The high-energy gammas from the SNF will generate some power directly via Compton scattering and the photoelectric effect, and the generated visible photons output from the scintillator material can also be converted to electrical power in a manner similar to that of a standard solar cell. Upon successful implementation of an energy conversion device based on this new gammavoltaic principle, this inherent power source could then be utilized within SNF storage casks to drive a tamper-proof, low-power, electronic detection/security monitoring system for the spent fuel. The current project has addressed several aspects associated with this new energy conversion concept, including the development of a base conceptual design for an inherent gamma-induced power conversion unit for SNF monitoring, the characterization of the radiation environment that can be expected within a typical SNF storage system, the initial evaluation of Konarka's base solar cell design, the design and fabrication of a range of new cell materials and geometries at Konarka's manufacturing facilities, and the irradiation testing and evaluation of these new cell designs within the UML Radiation Laboratory. The primary focus of all this work was to establish the proof of concept of the basic gammavoltaic principle using a new class of dye-sensitized photon converter (DSPC) materials based on KTI's original DSSC design. In achieving this goal, this report clearly establishes the viability of the basic gammavoltaic energy conversion concept, yet it also identifies a set of challenges that must be met for practical implementation of this new technology.

White,John R.; Kinsmen,Douglas; Regan,Thomas M.; Bobek,Leo M.

2005-08-29

112

Speed, Acceleration, and Velocity: Level II, Unit 9, Lesson 1; Force, Mass, and Distance: Lesson 2; Types of Motion and Rest: Lesson 3; Electricity and Magnetism: Lesson 4; Electrical, Magnetic, and Gravitational Fields: Lesson 5; The Conservation and Conversion of Matter and Energy: Lesson 6; Simple Machines and Work: Lesson 7; Gas Laws: Lesson 8; Principles of Heat Engines: Lesson 9; Sound and Sound Waves: Lesson 10; Light Waves and Particles: Lesson 11; Program. A High.....  

ERIC Educational Resources Information Center

This self-study program for high-school level contains lessons on: Speed, Acceleration, and Velocity; Force, Mass, and Distance; Types of Motion and Rest; Electricity and Magnetism; Electrical, Magnetic, and Gravitational Fields; The Conservation and Conversion of Matter and Energy; Simple Machines and Work; Gas Laws; Principles of Heat Engines;…

Manpower Administration (DOL), Washington, DC. Job Corps.

113

2007 Survey of Energy Resources World Energy Council 2007 Ocean Thermal Energy Conversion COUNTRY NOTES  

E-print Network

2007 Survey of Energy Resources World Energy Council 2007 Ocean Thermal Energy Conversion 573 and personal communication. Valuable inputs were provided by Don Lennard of Ocean Thermal Energy Conversion in the technology. #12;2007 Survey of Energy Resources World Energy Council 2007 Ocean Thermal Energy Conversion 574

114

Mode conversion in a magnetic photonic crystal waveguide  

NASA Astrophysics Data System (ADS)

In this work, we have reported a theoretical study of a magnetic photonic crystal waveguide (also called a magneto photonic crystal waveguide). This structure is formed by a triangular lattice of air holes in a bismuth iron garnet (BIG) film, grown on gallium gadolinium garnet substrates. Nonreciprocal TE-TM mode conversion is caused by the Faraday rotation if the magnetization is aligned along the z-axis, parallel to mode of propagation. The properties of this phenomenon are simulated using the beam propagation method. The conversion output has been simulated, and the Faraday rotation and modal birefringence have been calculated by varying the gyrotropy and the thickness of the BIG film. This magnetic photonic crystal waveguide has the advantage of enhancing Faraday rotation in optical isolators.

Otmani, H.; Bouchemat, M.; Hocini, A.; Boumaza, T.

2014-06-01

115

Energy Conversion at Micro and Nanoscale  

NASA Astrophysics Data System (ADS)

Energy management is considered a task of strategic importance in contemporary society. It is a common fact that the most successful economies of the planet are the economies that can transform and use large quantities of energy. In this talk we will discuss the role of energy with specific attention to the processes that happens at micro and nanoscale. The description of energy conversion processes at these scales requires approaches that go way beyond the standard equilibrium termodynamics of macroscopic systems. In this talk we will address from a fundamental point of view the physics of the dissipation of energy and will focus our attention to the energy transformation processes that take place in the modern micro and nano information and communication devices.

Gammaitoni, Luca

2014-11-01

116

Solar energy conversion with fluorescent collectors  

Microsoft Academic Search

A new principle for solar energy conversion is proposed and evaluated theoretically. Collection and concentration of direct\\u000a and diffuse radiation is possible by the use of a stack of transparent sheets of material doped with fluorescent dyes. High\\u000a efficiency of light collection can be achieved by light guiding and special design of collectors. The optical path length\\u000a in a triangular

A. Goetzberger; W. Greubel

1977-01-01

117

Thermoelectric energy conversion with solid electrolytes  

Microsoft Academic Search

The alkali metal thermoelectric converter (AMTEC) is a device for the direct conversion of heat to electrical energy. The sodium ion conductor beta-double prime-alumina is used to form a high-temperature regenerative concentration cell for elemental sodium. An AMTEC of mature design should have an efficiency of 20 to 40 percent, a power density of 0.5 kilowatt per kilogram or more,

T. Cole

1983-01-01

118

26th Intersociety Energy Conversion Engineering Conference  

Microsoft Academic Search

An overview is presented of the NASA-Lewis Free-Piston Stirling Space Power Convertor Technology Program. The goal is to develop the technology base needed to meet the long duration, high capacity power requirements for future NASA space initiatives. Efforts are focused upon increasing system power output and system thermal and electric energy conversion efficiency at least fivefold over current SP-100 technology,

J. E. Dudenhoefer; J. M. Winter

1991-01-01

119

Enhancing molecular conversion efficiency by a magnetic field pulse sequence  

NASA Astrophysics Data System (ADS)

We propose a strategy to enhance the atom-to-molecule conversion efficiency near a Feshbach resonance. Based on the mean-field approximation, we derive the fixed point solutions of the classical Hamiltonian. Rabi oscillation between the atomic and molecular states around fixed point solutions and its oscillation period are discussed. By designing a sequence of magnetic field pulses in analogy with Ramsey experiments, we show that a much higher atom-to-molecule conversion efficiency can be accessed by tuning the pulse durations appropriately.

Xu, Xiao-Qiang; Lu, Li-Hua; Li, You-Quan

2009-09-01

120

An efficient experimental method for high power direct drive wind energy conversion systems  

Microsoft Academic Search

Because of energy shortage and environment pollution, the renewable energy, especially wind energy has become more and more considerable all over the world. Direct drive wind energy conversion systems based on multipole permanent magnet synchronous generator (PMSG) have some advantages such as no gearbox, high power density, high precision and easy to control. In our research project, a 2MW direct

Weihao Hu; Yue Wang; Weizheng Yao; Jinlong Wu; Hailong Zhang; Zhaoan Wang

2008-01-01

121

Nanoengineered Materials for Thermoelectric Energy Conversion  

NASA Astrophysics Data System (ADS)

In this chapter we review recent advances in nanoengineered materials for thermoelectric energy conversion. We start by a brief overview of the fundamental interactions between heat and electricity, i.e., thermoelectric effects. A key requirement to improve the energy conversion efficiency is to increase the Seebeck coefficient (S) and the electrical conductivity (? ), while reducing the thermal conductivity (?). Nanostructures make it possible to modify the fundamental trade-offs between the bulk material properties through the changes in the density of states and interface effects on the electron and phonon transport. We will review recent experimental and theoretical results on superlattice and quantum dot thermoelectrics, nanowires, thin-film microrefrigerators, and solid-state thermionic power generation devices. In the latter case, the latest experimental results for semimetal rare-earth nanoparticles in a III-V semiconductor matrix as well as nitride metal/semiconductor multilayers will be discussed. We will briefly describe recent developments in nonlinear thermoelectrics, as well as electrically pumped optical refrigeration and graded thermoelectric materials. It is important to note that, while the material thermoelectric figure of merit (Z = S2? /? ) is a key parameter to optimize, one has to consider the whole system in an energy conversion application, and system optimization sometimes places other constraints on the materials.We will also review challenges in the experimental characterization of thin film thermoelectric materials. Finally, we will assess the potential of some of the more exotic techniques such as thermotunneling and bipolar thermoelectric effects.

Shakouri, Ali; Zebarjadi, Mona

122

E2I EPRI Assessment Offshore Wave Energy Conversion Devices  

E-print Network

E2I EPRI Assessment Offshore Wave Energy Conversion Devices Report: E2I EPRI WP ­ 004 ­ US ­ Rev 1 #12;E2I EPRI Assessment - Offshore Wave Energy Conversion Devices Table of Contents Introduction Assessment - Offshore Wave Energy Conversion Devices Introduction E2I EPRI is leading a U.S. nationwide

123

Promising applications of the liquid metal MHD energy conversion technology  

Microsoft Academic Search

Applications of the liquid-metal MHD (magnetohydrodynamic) energy conversion technology that could benefit from its unique features are reviewed with emphasis on applications that might be realized in the relatively near future and on the OMACON (optimized magnetohydrodynamic conversion) concept. Included among the promising applications are cogeneration, energy recovery from industrial processes involving the use of molten metals, energy conversion from

H. Branover; A. El-Boher; E. Greenspan; A. Barak

1989-01-01

124

Direct-Write Piezoelectric Polymeric Nanogenerator with High Energy Conversion  

E-print Network

Direct-Write Piezoelectric Polymeric Nanogenerator with High Energy Conversion Efficiency Chieh have shown repeatable and consistent electrical outputs with energy conversion efficiency an order for efficient conversion of mechanical energy into electricity. Recent work in the field of nanomaterials has

Lin, Liwei

125

Innovative oxide materials for electrochemical energy conversion  

NASA Astrophysics Data System (ADS)

Research in functional materials has progressed from those materials exhibiting structural to electronic functionality. The study of ion conducting ceramics ushers in a new era of ``chemically functional materials.'' This chemical functionality arises out of the defect equilibria of these materials, and results in the ability to transport chemical species and actively participate in chemical reactions at their surface. Moreover, this chemical functionality provides a promise for the future whereby the harnessing of our natural hydrocarbon energy resources can shift from inefficient and polluting combustion - mechanical methods to direct electrochemical conversion. The unique properties of these materials and their applications will be described. The focus will be on the application of ion conducting ceramics to energy conversion and storage, chemical sensors, chemical separation and conversion, and life support systems. Results presented will include development of record high power density (3 kW/kg) solid oxide fuel cells, NOx/CO species selective solid-state sensors, high yield membrane reactors, and regenerative life support systems that reduce CO2 to O2 and solid C.

Wachsman, Eric D.

2012-02-01

126

Thermophotovoltaic Energy Conversion for Space Applications  

NASA Astrophysics Data System (ADS)

Thermophotovoltaic (TPV) energy conversion cells have made steady and over the years considerable progress since first evaluated by Lockheed Martin for direct conversion using nuclear power sources in the mid 1980s. The design trades and evaluations for application to the early defensive missile satellites of the Strategic Defense Initiative found the cell technology to be immature with unacceptably low cell efficiencies comparable to thermoelectric of <10%. Rapid advances in the epitaxial growth technology for ternary compound semiconductors, novel double hetero-structure junctions, innovative monolithic integrated cell architecture, and bandpass tandem filter have, in concert, significantly improved cell efficiencies to 25% with the promise of 35% using solar cell like multi-junction approach in the near future. Recent NASA sponsored design and feasibility testing programs have demonstrated the potential for 19% system efficiency for 100 We radioisotopic power sources at an integrated specific power of ~14 We/kg. Current state of TPV cell technology however limits the operating temperature of the converter cells to < 400K due to radiator mass consideration. This limitation imposes no system mass penalty for the low power application for use with radioisotopes power sources because of the high specific power of the TPV cell converters. However, the application of TPV energy conversion for high power sources has been perceived as having a major impediment above 1 kWe due to the relative low waste heat rejection temperature. We explore this limitation and compare the integrated specific power of TPV converters with current and projected TPV cells with other advanced space power conversion technologies. We find that when the redundancy needed required for extended space exploration missions is considered, the TPV converters have a much higher range of applicability then previously understood. Furthermore, we believe that with a relatively modest modifications of the current epitaxial growth in MOCVD, an optimal cell architecture for elevated TPV operation can be found to out-perform the state-of-the-art TPV at an elevated temperature.

Teofilo, V. L.; Choong, P.; Chen, W.; Chang, J.; Tseng, Y.-L.

2006-01-01

127

Ocean thermal energy conversion: Materials issues  

NASA Astrophysics Data System (ADS)

The Ocean thermal Energy Conversion (OTEC) Program, in the Ocean Energy Technology Division of the U.S. Department of Energy, is concerned with the development of options that can be utilized to extract and distribute significant amounts of energy from the ocean. The biofouling control and materials portion of the program is concerned with the development of effective and environmentally acceptable methods to minimize biofouling and corrosion in high thermal conductivity materials suitable for use in heat exchangers and condensers. The mechanical and chemical techniques employed for biofouling control are reviewed and the recent success with chlorination is presented. The corrosion of aluminum alloys, copper alloys, stainless steel, stainless alloys, and titanium in near-surface warm and deep cold water is reviewed with emphasis on aluminum alloys. The major materials issues are reviewed with emphasis on lifetime and cost.

Darby, J. B., Jr.

128

Ocean energy conversion systems annual research report  

SciTech Connect

Alternative power cycle concepts to the closed-cycle Rankine are evaluated and those that show potential for delivering power in a cost-effective and environmentally acceptable fashion are explored. Concepts are classified according to the ocean energy resource: thermal, waves, currents, and salinity gradient. Research projects have been funded and reported in each of these areas. The lift of seawater entrained in a vertical steam flow can provide potential energy for a conventional hydraulic turbine conversion system. Quantification of the process and assessment of potential costs must be completed to support concept evaluation. Exploratory development is being completed in thermoelectricity and 2-phase nozzles for other thermal concepts. Wave energy concepts are being evaluated by analysis and model testing with present emphasis on pneumatic turbines and wave focussing. Likewise, several conversion approaches to ocean current energy are being evaluated. The use of salinity resources requires further research in membranes or the development of membraneless processes. Using the thermal resource in a Claude cycle process as a power converter is promising, and a program of R and D and subsystem development has been initiated to provide confirmation of the preliminary conclusion.

Not Available

1981-03-01

129

Thermal to electricity conversion using thermal magnetic properties  

DOEpatents

A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

2010-04-27

130

Optimized design of a permanentmagnet tubular linear generator for wave energy conversion  

Microsoft Academic Search

A permanent magnet tubular linear generator (PMTLG) is presented for wave energy conversion due to its direct drive characteristics. Finite Element method is implemented to calculate and optimize the waveform of magnetic field along air-gap of PMTLG with Halbach array. The computational results are validated by experimental ones.

Haitao Yu; Bang Yuan; Hengshan Yang; Minqiang Hu; Lei Huang

2010-01-01

131

Wind energy conversion: is it environmentally acceptable  

SciTech Connect

An overview of the current status of the knowledge regarding potential environmental impediments to the commercialization of Wind Energy Conversion System (WECS) is presented. The text also identifies pertinent studies conducted in each area and summarizes the conclusions of the studies. In rough order of importance, the identified environmental impediments to the widespread use of WECS are as follows: electromagnetic interference; land use; aesthetics visual pollution; noise; and biophysical effects. Assessment of the environmental impacts of wind energy conversion system as they reflect to the five generic areas investigated is summarized. The results indicate that of the five generic areas, only the television video signal interference and specific very local impacts related to land use and aesthetics are nonnegligible factors. The severity of the television interference problem has been well studied and verified analytical relationships have been established for determining the extent of the interference zone, which in even the worst case is limited to 4 to 6 km (2 or 3 miles) from a WECS with a rotor diameter of 38 m (125 ft). Fringe reception areas, where the worst interference is encountered, generally have access to cable television, which eliminates the problem. With smaller rotor diameters, the problem should be negligible and additional investigations are currently underway to verify this hypothesis. The potential problems relating to land use and aesthetics are site-specific and depending on the nature of the problem may be relatively hard to resolve. However, it can be concluded in general there appear to be no insurmountable environmental constraints on the general widespread use of wind energy conversion systems.

Cingo, R.P.

1980-11-01

132

Preliminary studies of direct energy conversion in a D- sup 3 He fusion reactor  

Microsoft Academic Search

In this paper, a direct energy conversion method is proposed for a D-³He inertial confinement fusion reactor. The method utilizes inductive energy recovery through pickup coils in the plasma chamber in which mirror magnetic fields are applied. A method to reduce the problems regarding the handling of ultrahigh voltage inherent in energy recovery of this type is proposed that divides

K. Mima; H. Takabe; Y. Kitagawa; S. Nakai; K. Yoshikawa; O. Morimaya; H. Takase; T. Tajima; Y. Kosaki

1992-01-01

133

River Inflow Characteristics for Hydrokinetic Energy Conversion  

NASA Astrophysics Data System (ADS)

Most of our knowledge on current energy conversion resource characterization is derived from the wind power industry. River current resource characterization for hydrokinetic technologies can certainly borrow from this knowledge base, but must consider unique attributes associated with river hydrodynamics. Published turbulent flow data from large rivers, a canal and laboratory flumes are reviewed to determine the range of velocities and longitudinal turbulence intensities acting on hydrokinetic technologies, and also to evaluate the validity of classical models that describe the depth variation of the time-mean velocity and turbulent Reynolds stresses. A key challenge in river flow characterization is the high variability of depth and flow over the design life of a hydrokinetic device. This variation will have significant effects on the inflow mean velocity and turbulence intensity experienced by the hydrokinetic device, which requires further investigation. These effects may significantly alter estimates of energy production, structural loads, and ultimately the cost of energy at a river resource site.

Neary, V. S.; Sale, D.; Gunawan, B.

2011-12-01

134

Linear mode conversion of Langmuir/z-mode waves to radiation: Scalings of conversion efficiencies and propagation angles with temperature and magnetic field orientation  

NASA Astrophysics Data System (ADS)

Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in an inhomogeneous plasma. It is relevant to laboratory plasmas and multiple solar system radio emissions, such as continuum radiation from planetary magnetospheres and type II and III radio bursts from the solar corona and solar wind. This paper simulates LMC of waves defined by warm, magnetized fluid theory, specifically the conversion of Langmuir/z-mode waves to electromagnetic (EM) radiation. The primary focus is the calculation of the energy and power conversion efficiencies for LMC as functions of the angle of incidence ? of the Langmuir/z-mode wave, temperature ? =Te/mec2, adiabatic index ?, and orientation angle ? between the ambient density gradient ?N0 and ambient magnetic field B0 in a warm, unmagnetized plasma. The ratio of these efficiencies is found to agree well as a function of ?, ?, and ? with an analytical relation that depends on the group speeds of the Langmuir/z and EM wave modes. The results demonstrate that the energy conversion efficiency ? is strongly dependent on ??, ? and ?, with ? ?(??)1/2 and ??(??)1/2. The power conversion efficiency ?p, on the other hand, is independent of ?? but does vary significantly with ? and ?. The efficiencies are shown to be maximum for approximately perpendicular density gradients (? ?90°) and minimal for parallel orientation (? =0°) and both the energy and power conversion efficiencies peak at the same ?.

Schleyer, F.; Cairns, Iver H.; Kim, E.-H.

2013-03-01

135

Carbon aerogel electrodes for direct energy conversion  

DOEpatents

A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

Mayer, Steven T. (San Leandro, CA); Kaschmitter, James L. (Pleasanton, CA); Pekala, Richard W. (Pleasant Hill, CA)

1997-01-01

136

Carbon aerogel electrodes for direct energy conversion  

DOEpatents

A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes is described, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome. 1 fig.

Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

1997-02-11

137

Energy conversion device with improved seal  

DOEpatents

An energy conversion device comprising an improved sealing member adapted to seal a cation-permeable casing to the remainder of the device. The sealing member comprises a metal substrate which (i) bears a nonconductive and corrosion resistant coating on the major surface to which said casing is sealed, and (ii) is corrugated so as to render it flexible, thereby allowing said member to move relative to said casing without cracking the seal therebetween. Corrugations may be circumferential, radial, or both radial and circumferential so as to form dimples. The corrugated member may be in form of a bellows or in a substantially flat form, such as a disc.

Miller, Gerald R. (Salt Lake City, UT); Virkar, Anil V. (Midvale, UT)

1980-01-01

138

Energy transfer processes in solar energy conversion  

SciTech Connect

By combining picosecond optical experiments and detailed statistical mechanics theory we continue to increase our understanding of the complex interplay of structure and dynamics in important energy transfer situations. A number of different types of problems will be focused on experimentally and theoretically. They are excitation transport among chromophores attached to finite size polymer coils; excitation transport among chromophores in monolayers, bilayers, and finite and infinite stacks of layers; excitation transport in large vesicle systems; and photoinduced electron transfer in glasses and liquids, focusing particularly on the back transfer of the electron from the photogenerated radical anion to the radical cation. 33 refs., 13 figs.

Fayer, M.D.

1986-11-01

139

Thermophotovoltaic energy conversion: Technology and market potential  

SciTech Connect

This report contains material displayed on poster panels during the Conference. The purpose of the contribution was to present a summary of the business overview of thermophotovoltaic generation of electricity and its market potential. The market analysis has shown that the TPV market, while currently still in an early nucleation phase, is evolving into a range of small niche markets out of which larger-size opportunities can emerge. Early commercial applications on yachts and recreational vehicles which require a quiet and emission-free compact electrical generator fit the current TPV technology and economics. Follow-on residential applications are attractive since they can combine generation of electricity with space and hot water heating in a co-generation system. Development of future markets in transportation, both private and communal or industrial, will be driven by legislation requiring emission-free vehicles, and by a reduction in TPV systems cost. As a result of {open_quote}{open_quote}moving down the learning curve,{close_quote}{close_quote} growing power and consumer markets are predicted to come into reach of TPV systems, a development favored by high overall energy conversion efficiency due to high radiation energy density and to high electric conversion efficiency available with photovoltaic cells. {copyright} {ital 1996 American Institute of Physics.}

Ostrowski, L.J.; Pernisz, U.C. [Dow Corning Corporation, Midland, Michigan 48686 (United States); Fraas, L.M. [JX Crystals, Incorporated, Issaquah, Washington 98027 (United States)

1996-02-01

140

Recycling of Wasted Energy: Thermal to Electrical Energy Conversion  

NASA Astrophysics Data System (ADS)

Harvesting useful electric energy from ambient thermal gradients and/or temperature fluctuations is immensely important. For many years, a number of direct and indirect thermal-to-electrical energy conversion technologies have been developed. Typically, direct energy conversion is achieved by using thermoelectric generators or thermogalvanic cells; indirect energy conversion is achieved by using Organic Rankine Cycle or Sterling Engines. On the one hand, there is a fundamental technical difficulty, thermal shorting, that limits the energy conversion efficiency of direct thermoelectric energy conversion methods. While extensive study has been conducted in this area, currently the portion of thermal energy that can be converted to electricity is still small. On the other hand, the indirect energy conversion systems tend to be complicated and expensive. Thus, existing energy harvesting technologies are less economically competitive compared with the grid power. To develop advanced energy harvesting systems, a novel concept using nanoporous materials is investigated. Nanoporous materials have been widely used as advanced absorbents. Because of their ultra-large surface areas (100--2000 m2/g), they can adsorb a large amount of ions when they are immersed in electrolyte solutions. The ion adsorption capacity is thermally dependent. If two nanoporous electrodes are placed at different temperatures, they adsorb different amounts of ions, generating a net output voltage. The thermally driven ion motion causes a transient current, which can be reactivated through temperature fluctuation or internal grounding. The two electrodes are isolated; that is, the direct heat loss between them is minimized. Our experimental data have shown encouraging results: the output voltage and the energy conversion efficiency are higher than that of conventional thermoelectric materials by orders of magnitude. Our study will not only lead to the development of high-performance thermal energy harvesting systems, but also shed light on fundamentals of electrophysics in nanoenvironment. The thermal effect on surface electrification (i.e. the capacitive effect) in nanopores is a new scientific area. Conventional interface theories have failed in explaining a number of experimental observations. We have carried out a systematic study of the effects of ions, solvent, electrode, cell configuration, etc. to understand the fundamental mechanisms and processes that govern the ion motion and charge transfer in nanopores.

Lim, Hyuck

141

OCEAN THERMAL ENERGY CONVERSION PROGRAMMATIC ENVIRONMENTAL ASSESSMENT  

SciTech Connect

Significant achievements in Ocean Thermal Energy Conversion (OTEC) technology have increased the probability of producing OTEC-derived power in this decade with subsequent large-scale commercialization to follow by the turn of the century. Under U.S. Department of Energy funding, Interstate Electronics has prepared an OTEC Programmatic Environmental Assessment (EA) that considers tne development, demonstration, and commercialization of OTEC power systems. The EA considers several tecnnological designs (open cycle and closed cycle), plant configurations (land-based, moored, and plantship), and power usages (baseload electricity and production of ammonia and aluminum). Potencial environmental impacts, health and safety issues, and a status update of international, federal, and state plans and policies, as they may influence OTEC deployments, are included.

Sands, M.Dale

1980-08-01

142

On the conversion of rest energy in horizon energy  

E-print Network

It is shown that the Verlinde formula for the entropy variation of a holographic screen is a consequence of the conversion of the particle energy in horizon energy. The special role played by the particular displacement $\\Delta x = c^{2}/a$ is emphasized, $a$ being the particle acceleration. Using the Heisenberg Principle we show that the energy on the causal horizon (viewed as a holographic screen) of an inertial observer is proportional to its radius, as for a black hole.

Hristu Culetu

2011-03-15

143

Hydrogen conversion on non-magnetic insulating surfaces  

NASA Astrophysics Data System (ADS)

Non-magnetic insulating catalysts are shown to be able to convert non-equilibrium mixtures of hydrogen by an electric mechanism. The molecular electrons feel the difference of temperature between the nuclei and the thermal bath, through their “Fermi” contact interaction, and consequently transfer the rotational angular momenta to the catalyst. This transfer, realized by the electrostatic interactions between the molecular and surface ionic electron clouds, is measured by non-diagonal exchange integrals. Our simple model of single-electron excitations interprets the experimental conversion rates recently observed on different surfaces (MOF or ASW) with different technics (infrared or ionization spectroscopy) and allows the study of the conversion rates in different contexts: thermal as well as transient, metallic or oxygen-induced, ion-molecule and molecule-molecule electron exchanges.

Ilisca, E.

2013-10-01

144

Proceedings of the 33. intersociety energy conversion engineering conference  

Microsoft Academic Search

These papers were presented at the Intersociety Energy Conversion Engineering Conference, August of 1998. The topics of the papers included aerospace power analyses and simulation, space energy conversion, applications and requirements for space power systems, space solar power, terrestrial energy, aerospace batteries, aerospace power management, aerospace power electronics, aircraft power, dual use technologies, electric propulsion, wireless energy transmission, terrestrial thermoelectric,

Anghaie

1998-01-01

145

Technology assessment of wind energy conversion systems  

SciTech Connect

Environmental data for wind energy conversion systems (WECSs) have been generated in support of the Technology Assessment of Solar Energy (TASE) program. Two candidates have been chosen to characterize the WECS that might be deployed if this technology makes a significant contribution to the national energy requirements. One WECS is a large machine of 1.5-MW-rated capacity that can be used by utilities. The other WECS is a small machine that is characteristic of units that might be used to meet residential or small business energy requirements. Energy storage systems are discussed for each machine to address the intermittent nature of wind power. Many types of WECSs are being studied and a brief review of the technology is included to give background for choosing horizontal axis designs for this study. Cost estimates have been made for both large and small systems as required for input to the Strategic Environmental Assessment Simulation (SEAS) computer program. Material requirements, based on current generation WECSs, are discussed and a general discussion of environmental impacts associated with WECS deployment is presented.

Meier, B. W.; Merson, T. J.

1980-09-01

146

Elemental processes of transport and energy conversion in Earth's magnetosphere  

NASA Astrophysics Data System (ADS)

In the last 5 years observations from several missions and ground based observatories have honed in on the most elemental aspects of flux transport and energy conversion. Dipolarization fronts and their counterpart in the distant magnetotail "anti-dipolarization" fronts, which together are refered to herein as "reconnection fronts", usher the recently reconnected flux tubes from the near-Earth X-points and in the process convert magnetic energy to particle energy and wave radiation. On the tailward side they are responsible for plasmoid formation and acceleration. On the earthward side they result in elemental substorm current wedges or wedglets, which were initially postulated from ground observations alone. Recent observations have revealed how the interaction of wedgelets and the inner magnetosphere takes place. Questions remain with regards to the physics of the energy transfer process from global magnetic energy to local heating and waves, and with regards to the initiation of the X-point activations in space. Observations indicate that the latter may be induced by polar cap or dayside activity, suggesting a direct link between dayside reconnection and nightside phenomena. The likely causal sequence of events and open questions in light of these recent observations, and the field's outlook in anticipation of upcoming coordinated observations from the international Heliophysics System Observatory will be discussed.

Angelopoulos, Vassilis

147

Modeling and analysis of energy conversion systems  

SciTech Connect

An investigation was conducted to assess the need for and the feasibility of developing a computer code that could model thermodynamic systems and predict the performance of energy conversion systems. To assess the market need for this code, representatives of a few industrial organizations were contacted, including manufacturers, system and component designers, and research personnel. Researchers and small manufacturers, designers, and installers were very interested in the possibility of using the proposed code. However, large companies were satisfied with the existing codes that they have developed for their own use. Also, a survey was conduced of available codes that could be used or possibly modified for the desired purpose. The codes were evaluated with respect to a list of desirable features, which was prepared as a result of the survey. A few publicly available codes were found that might be suitable. The development, verification, and maintenance of such a code would require a substantial, ongoing effort. 21 refs.

Den Braven, K.R. (Idaho Univ., Moscow, ID (USA). Dept. of Mechanical Engineering); Stanger, S. (EG and G Idaho, Inc., Idaho Falls, ID (USA))

1990-10-01

148

Lighter than air wind energy conversion system  

SciTech Connect

A lighter-than-air (Lta) wind energy conversion system (Wecs) is described wherein the lta envelope carries a main rotor and electrical generator to take advantage of high wind speeds available at high altitudes. The lta envelope is tethered to a ground based mooring system designed to provide self-orientation for the lta envelope. In a preferred embodiment, heavy mechanical transmissions are eliminated by providing a hollow bladed main rotor which drives an induction turbine positioned within a substantially linear duct which is, in turn, preferably located along the longitudinal axis of the lta envelope. The output of the induction turbine is coupled to an electrical generator whose output is, in turn, transmitted to the ground via the tethering system.

Benoit, W.R.

1982-09-21

149

Rotating flux compressor for energy conversion  

SciTech Connect

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.

Chowdhuri, P.; Linton, T.W.; Phillips, J.A.

1983-01-01

150

Direct energy conversion using liquid metals  

NASA Astrophysics Data System (ADS)

Liquid metals have excellent properties to be used as heat transport fluids due to their high thermal conductivity and their wide applicable temperature range. The latter issue can be used to go beyond limitations of existing thermal solar energy systems. Furthermore, the direct energy converter Alkali Metal Thermo Electric Converter (AMTEC) can be used to make intangible areas of energy conversion suitable for a wide range of applications. One objective is to investigate AMTEC as a complementary cycle for the next generation of concentrating solar power (CSP) systems. The experimental research taking place in the Karlsruhe Institute of Technology (KIT) is focused on the construction of a flexible AMTEC test facility, development, test and improvement of liquid-anode and vapor-anode AMTEC devices as well as the coupling of the AMTEC cold side to the heat storage tank proposed for the CSP system. Within this project, the investigations foreseen will focus on the analyses of BASE-metal interface, electrode materials and deposition techniques, corrosion and erosion of materials brought in contact with high temperature sodium. This prototype demonstrator is planned to be integrated in the KArlsruhe SOdium LAboratory (KASOLA), a flexible closed mid-size sodium loop, completely in-house designed, presently under construction at the Institute for Neutron Physics and Reactor Technology (INR) within KIT.

Onea, Alexandru; Diez de los Rios Ramos, Nerea; Hering, Wolfgang; Stieglitz, Robert; Moster, Peter

2014-12-01

151

Energy conversion for megawatt space power systems  

NASA Technical Reports Server (NTRS)

Large nuclear space power systems capable of continuously producing over one megawatt of electrical power for a several year period will be needed in the future. This paper presents the results of a study to compare applicable conversion technologies which were deemed to be ready for a time period of 1995 and beyond. A total of six different conversion technologies were studied in detail and compared on the basis of conversion efficiency, radiator area, overall system mass, and feasibility. Three static, modular conversion technologies were considered; these include: AMTEC, thermionic, and thermoelectric conversion. The other three conversion technologies are heat engines which involve dynamic components. The dynamic systems analyzed were Brayton, Rankine, and the free piston Stirling engine. Each of the conversion techniques was also examined for limiting characteristics and an attempt was made to identify common research needs and enabling technologies.

Ewell, R.

1983-01-01

152

Ocean thermal energy conversion: Perspective and status  

NASA Astrophysics Data System (ADS)

The use of the thermal gradient between the warm surface waters and the deep cold waters of tropical oceans was first proposed by J. A. d'Arsonval in 1881 and tried unsuccessfully by George Claude in 1930. Interest in Ocean Thermal Energy Conversion (OTEC) and other renewable energy sources revived in the 1970s as a result of oil embargoes. At that time, the emphasis was on large floating plants miles from shore producing 250 to 400 MW for maintained grids. When the problems of such plants became better understood and the price of oil reversed its upward trend, the emphasis shifted to smaller (10 MW) shore based plants on tropical islands. Such plants would be especially attractive if they produce fresh water as a by-product. During the past 15 years, major progress has been made in converting OTEC unknowns into knowns. Mini-OTEC proved the closed cycle concept. Cost effective heat exchanger concepts were identified. An effective biofouling control technique was discovered. Aluminum was determined to be promising for OTEC heat exchangers. Heat transfer augmentation techniques were identified, which promised a reduction on heat exchanger size and cost. Fresh water was produced by an OTEC open cycle flash evaporator, using the heat energy in the seawater itself. The current R and D emphasis is on the design and construction of a test facility to demonstrate the technical feasibility of the open cycle process. The 10 MW shore-based, closed cycle plant can be built with today's technology; with the incorporation of a flash evaporator, it will produce fresh water as well as electrical power; both valuable commodities on many tropical islands. The open cycle process has unknowns that require solution before the technical feasibility can be demonstrated. The economic viability of either cycle depends on reducing the capital costs of OTEC plants and on future trends in the costs of conventional energy sources.

Thomas, Anthony; Hillis, David L.

153

Science of Nanofluidics and Energy Conversion  

NASA Astrophysics Data System (ADS)

The emerging subject of nanofluidics, where solids and fluids interact closely at the nanoscale, has exhibited radically different from their macroscopic counterparts (and sometimes counterintuitive), and yet relatively less explored. On the other hand, the resulting unique properties may contribute to a number of innovative functions with fascinating applications. Among various exciting potential applications, an important and ever expanding one is to provide alternative solutions to energy conversion with high efficiency, including energy absorption, actuation and harvesting. In this dissertation, we first report a novel protection mechanism of energy capture through which an intensive impact or blast energy can be effectively mitigated based on a nonwetting liquid-nanoporous material system. The captured energy is stored in nanopores in the form of potential energy of intercalated water molecules for a while, and not necessarily converted to other forms of energy (e.g. heat). At unloading stage, the captured energy will be released gradually due to the hydrophobic inner surfaces of nanopores through the diffusion of water molecules out of nanopores, thus making this system reusable. Several key controlling factors including impacting velocity, nanopore size, nanopore structure, and liquid phase have been investigated on the capacity of energy capture. The molecular mechanism is elucidated through the study of water molecular distributions inside nanpores. These molecular dynamic (MD) findings are quantitatively verified by a parallel blast experiment on a zeolite/water system. During the transport of confined liquid molecules, the friction resistance exerted by solid atoms of nanopores to liquid molecules will dissipate part of energy, and is highly dependent of temperature of liquid molecules and wall morphology of nanopores. Using MD simulations, the effects of temperature and wall roughness on the transport resistance of water molecules inside nanopores are investigated in Chapter 3. The effective shear stress and nominal viscosity that dominate the nanofluidic transport resistance are extracted and coupled with the nanopore size, transport rate, and liquid property. The molecular-level mechanisms are revealed through the study of the density profile and hydrogen bonding of confined liquid molecules. A parallel experiment on a nanoporous carbon-liquid system is carried out and qualitatively verifies MD findings. Motived by the well-known thermo- and electro-capillary effect, Chapter 4 and Chapter 5 present a conceptual design of thermal and electric actuation system by adjusting the relative hydrophobicity of a liquid-nanoporous system through a thermal and electric field, respectively. The thermally and electrically dependent infiltration behaviors of liquids into nanopores are analyzed by using MD simulations. The fundamental molecular characteristics, including the density profile, contact angle, and surface tension of the confined liquid molecules, are examined to reveal underlying mechanisms. The energy density, power density, and efficiency of both thermal and electric actuation systems are explored and their variations with pore size, solid phase, and liquid phase are evaluated. Thermally and electrically controlled infiltration experiments on a zeolite-water /electrolyte solution system are performed accordingly to qualitatively validate these findings. These energy actuation systems can also become high density thermal or electric storage devices with proper designs. Energy harvesting by the flow of a hydrochloric acid-water solution through a nanopore is explored using atomistic simulations in the last chapter. Through ion configurations near the pore wall, an averaged ion drifting velocity is determined, and the induced voltage along the axial direction is obtained as a function of key material parameters, including the applied flow rate, environmental temperature, solution concentration and nanopore size. The molecular mechanism of ion hopping and motion is revealed. This study shed light on harvesting

Xu, Baoxing

154

Solar energy conversion using surface plasmons for broadband energy transport  

NASA Technical Reports Server (NTRS)

A new strategy for efficient solar energy conversion based on parallel processing with surface plasmons is introduced. The approach is unique in identifying: (1) a broadband carrier with suitable range for energy transport, and (2) a technique to extract more energy from the more energetic photons, without sequential losses or unique materials for each frequency band. The aim is to overcome the fundamental losses associated with the broad solar spectrum and to achieve a higher level of spectrum splitting than has been possible in semiconductor systems.

Anderson, L. M.

1982-01-01

155

Axial inlet conversion to a centrifugal compressor with magnetic bearings  

SciTech Connect

NOVA's Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, US, and British Columbia. There is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level that allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).

Novecosky, T. (NOVA Corp., Edmonton, Alberta (Canada))

1994-01-01

156

Power electronics applications in wind energy conversion system: A review  

Microsoft Academic Search

This paper gives a review on the power electronic applications for wind energy conversion systems. Different types of wind energy conversion system (WECS) with different generators and power electronic converters are described, and different technical features are compared. The electrical topologies of WECS with different wind turbines are summarized and the possible uses of power electronic converters with wind farms

R. D. Shukla; R. K. Tripathi; S. Gupta

2010-01-01

157

Some preliminary considerations on photovoltaic conversion of solar energy  

Microsoft Academic Search

Tentative calculations on the feasibility, cost effectiveness, and overall reliability of solar energy via photovoltaic conversion are carried out. It is estimated that the cost of solar energy conversion will have to be cut by factors of 100 to 200 for it to become competitive with other sources of large-scale power in the foreseeable future. The importance of exploitation of

A. Egidi; G. V. Pallottino

1976-01-01

158

Semiconductor Nanowires for Energy Conversion Allon I. Hochbaum*,  

E-print Network

Semiconductor Nanowires for Energy Conversion Allon I. Hochbaum*, and Peidong Yang* Department. Introduction: Role of Materials in Energy Conversion 527 2. Why Are Semiconductor Nanowires Special? 527 3 in materials with nanometer-scale dimensions. Semiconductor nanowires, a subset of these materials, have

Wu, Zhigang

159

Vibrational energy redistribution in glyoxal following internal conversion  

E-print Network

Vibrational energy redistribution in glyoxal following internal conversion R. Naaman,a) D. M 4 June 1979; accepted 10 August 1979) The vibrational redistribution of energy following internal that combination bands of low quanta of vibrations are the accepting levels in the internal conversion process

Zare, Richard N.

160

Thermoelectric, thermionic and thermophotovoltaic energy conversion Ali Shakouri  

E-print Network

Thermoelectric, thermionic and thermophotovoltaic energy conversion Ali Shakouri Jack Baskin School higher efficiency in energy conversion devices and to approach the limit given by the entropy generation of Engineering University of California Santa Cruz, CA 95064 ali@soe.ucsc.edu Abstract Key characteristics

161

Proceedings of the 25th intersociety energy conversion engineering conference  

Microsoft Academic Search

This book contains the proceedings of the 25th Intersociety Energy Conversion Engineering Conference. Volume 5 is organized under the following headings: Photovoltaics I, Photovoltaics II, Geothermal power, Thermochemical conversion of biomass, Energy from waste and biomass, Solar thermal systems for environmental applications, Solar thermal low temperature systems and components, Solar thermal high temperature systems and components, Wind systems, Space power

P. A. Nelson; W. W. Schertz; R. H. Till

1990-01-01

162

Wind Energy Conversion Using a Self-Excited Induction Generator  

Microsoft Academic Search

A wind energy conversion scheme using an induction machine driven by a variable speed wind turbine is described. Excitation control has been obtained by employing a single value capacitor and thyristor controlled inductor. Wind speed cube law is proposed to be followed in loading the induction machine for maximising energy conversion. Performance characteristics of the generation scheme have been evaluated

G. Raina; O. P. Malik

1983-01-01

163

Magnetic Helicity, Magnetic Energy, and EUV Variability  

Microsoft Academic Search

We estimate the injection rates of magnetic helicity and magnetic energy with data obtained by the Advanced Stokes Polarimeter (ASP) and SOHO\\/MDI. We find that magnetic helicity injected by the photospheric shear motion has a weak correlation with the variability of the EUV intensity, which would be related to sporadic heating of the corona. Three different methodologies to derive the

Y. Sakamoto

2004-01-01

164

Performance of Tornado Wind Energy Conversion Systems  

SciTech Connect

The flow characteristics and power production capabilities of the Tornado Wind Energy Conversion System (TWECS) are examined. Experimental results indicate that the confined vortex in the tower of TWECS rotates approximately as a solid body and only supplements total power production, most of which comes from the tower acting as a bluff body. Wrapped tower experiments were performed by fitting a plastic shroud 360 deg around the tower from the top of the bottom inlet to the tower exit level which transformed the TWECS into a hollow, raised cylinder. Coefficient of power is compared for louvered towers vs. wrapped tower. The fact that the wrapped tower performs as well as the louvered tower suggests that it is the pressure difference between the bottom inlet region and the region above the tower (where the pressure of the ambient flow will be somewhat reduced owing to its acceleration over the bluff body of the tower) which determines the vertical force on the fluid within the tower.

Volk, T.

1982-09-01

165

Theoretical investigation of solar energy conversion and water oxidation catalysis  

E-print Network

Solar energy conversion and water oxidation catalysis are two great scientific and engineering challenges that will play pivotal roles in a future sustainable energy economy. In this work, I apply electronic structure ...

Wang, Lee-Ping

2011-01-01

166

Electric energy by direct conversion from gravitational energy: a gift from superconductivity  

E-print Network

We theoretically demonstrate that electromagnetic energy can be obtained by direct, lossless, conversion from gravitational and kinetic energies. For this purpose we discuss the properties of an electromechanical system which consists of a superconducting coil submitted to a constant external force and to magnetic fields. The coil oscillates and has induced in it a rectified electrical current whose magnitude may reach hundreds of Ampere. There is no need for an external electrical power source for the system to start out and it can be kept working continuously if linked to large capacitors. We extensively discuss the issue of energy dissipation in superconductors and show that the losses for such a system can be made extremely small for certain operational conditions, so that by reaching and keeping resonance the system main application should be in magnetic energy storage and transmission.

Osvaldo F. Schilling

2003-09-01

167

Evidence of the theoretically predicted seismo-magnetic conversion  

NASA Astrophysics Data System (ADS)

Seismo-electromagnetic phenomena in porous media arise from seismic wave-induced fluid motion in the pore space, which perturbs the equilibrium of the electric double layer. This paper describes with details the original experimental apparatus built within the ultra-shielded chamber of the Low Noise Underground Laboratory of Rustrel (France). We measured seismo-magnetic conversions in moist sand using two induction magnetometers, and a pneumatic seismic source to generate the seismic wave propagation. We ensured to avoid the magnetometer vibrations, which could induce strong disturbances from induction origin. Interpretation of the data is improved by an analytical description of phase velocities for fast (Pf) and slow (Ps) longitudinal modes, transverse mode (S) as well as the extensional mode due to the cylindrical geometry of the sample. The purpose of this paper is to provide elements to measure correctly coseismic seismomagnetic fields and to specify their amplitude. The seismic arrivals recorded in the sample showing a 1200-1300ms-1 velocity have been associated to P and extensional waves. The measured seismo-magnetic arrivals show a velocity of about 800ms-1 close to the calculated phase velocity of S waves. Therefore, we show that the seismo-magnetic field is associated to the transverse part of the propagation, as theoretically predicted by Pride (1994), but never measured up to now. Moreover, the combined experimental and analytical approaches lead us to the conclusion that the measured seismo-magnetic field is probably about 0.035nT for a 1ms-2 seismic source acceleration (0.1g).

Bordes, Clarisse; Jouniaux, Laurence; Garambois, Stéphane; Dietrich, Michel; Pozzi, Jean-Pierre; Gaffet, Stéphane

2008-08-01

168

Contribution of ocean thermal energy conversion to world energy needs  

NASA Astrophysics Data System (ADS)

Ocean Thermal Energy Conversion (OTEC) can provide energy to all countries. It can deliver the energy (1) to regions bordered by warm ocean waters via direct electric-power transmission or (2) to other areas not bordered by warm ocean waters, via an energy-intensive material produced on OTEC plantships cruising on the high seas in the tropics. Ammonia is an outstanding choice for an energy-intensive material because it can (a) replace ammonia now made from natural gas to conserve fuel, (b) serve as a synthetic fuel, or (c) provide an easily transported, storable source of hydrogen for fuel cells to generate electric power where needed anywhere in the world. Costs of OTEC ammonia and of electricity delivered directly or via fuel cells are projected to be competitive with costs of electricity from coal or nuclear plants by 1990, if rapid OTEC development is pursued.

Avery, W. H.; Dugger, G. L.

1980-07-01

169

Linear mode conversion of Langmuir/z-mode waves to radiation: Scalings of conversion efficiencies and propagation angles with temperature and magnetic field orientation  

SciTech Connect

Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in an inhomogeneous plasma. It is relevant to laboratory plasmas and multiple solar system radio emissions, such as continuum radiation from planetary magnetospheres and type II and III radio bursts from the solar corona and solar wind. This paper simulates LMC of waves defined by warm, magnetized fluid theory, specifically the conversion of Langmuir/z-mode waves to electromagnetic (EM) radiation. The primary focus is the calculation of the energy and power conversion efficiencies for LMC as functions of the angle of incidence {theta} of the Langmuir/z-mode wave, temperature {beta}=T{sub e}/m{sub e}c{sup 2}, adiabatic index {gamma}, and orientation angle {phi} between the ambient density gradient {nabla}N{sub 0} and ambient magnetic field B{sub 0} in a warm, unmagnetized plasma. The ratio of these efficiencies is found to agree well as a function of {theta}, {gamma}, and {beta} with an analytical relation that depends on the group speeds of the Langmuir/z and EM wave modes. The results demonstrate that the energy conversion efficiency {epsilon} is strongly dependent on {gamma}{beta}, {phi} and {theta}, with {epsilon}{proportional_to}({gamma}{beta}){sup 1/2} and {theta}{proportional_to}({gamma}{beta}){sup 1/2}. The power conversion efficiency {epsilon}{sub p}, on the other hand, is independent of {gamma}{beta} but does vary significantly with {theta} and {phi}. The efficiencies are shown to be maximum for approximately perpendicular density gradients ({phi} Almost-Equal-To 90 Degree-Sign ) and minimal for parallel orientation ({phi}=0 Degree-Sign ) and both the energy and power conversion efficiencies peak at the same {theta}.

Schleyer, F.; Cairns, Iver H. [School of Physics, University of Sydney, NSW 2006 (Australia); Kim, E.-H. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

2013-03-15

170

A novel thermomechanical energy conversion cycle Ian M. McKinley, Felix Y. Lee, Laurent Pilon  

E-print Network

]. Other methods for direct mechanical to electrical energy conversion include electromagnet, electrostatic to convert ther- mal energy directly into electricity. Note that none of these energy conversion methods: Pyroelectric materials Direct energy conversion Waste heat harvesting Ferroelectric materials Olsen cycle

Pilon, Laurent

171

Plasmon-assisted radiolytic energy conversion in aqueous solutions  

NASA Astrophysics Data System (ADS)

The field of conventional energy conversion using radioisotopes has almost exclusively focused on solid-state materials. Herein, we demonstrate that liquids can be an excellent media for effective energy conversion from radioisotopes. We also show that free radicals in liquid, which are continuously generated by beta radiation, can be utilized for electrical energy generation. Under beta radiation, surface plasmon obtained by the metallic nanoporous structures on TiO2 enhanced the radiolytic conversion via the efficient energy transfer between plasmons and free radicals. This work introduces a new route for the development of next-generation power sources.

Kim, Baek Hyun; Kwon, Jae W.

2014-06-01

172

Plasmon-assisted radiolytic energy conversion in aqueous solutions  

PubMed Central

The field of conventional energy conversion using radioisotopes has almost exclusively focused on solid-state materials. Herein, we demonstrate that liquids can be an excellent media for effective energy conversion from radioisotopes. We also show that free radicals in liquid, which are continuously generated by beta radiation, can be utilized for electrical energy generation. Under beta radiation, surface plasmon obtained by the metallic nanoporous structures on TiO2 enhanced the radiolytic conversion via the efficient energy transfer between plasmons and free radicals. This work introduces a new route for the development of next-generation power sources. PMID:24918356

Kim, Baek Hyun; Kwon, Jae W.

2014-01-01

173

Modulated reconnection rate and energy conversion at the magnetopause under steady IMF conditions  

E-print Network

.1029/2007GL032868. 1. Introduction [2] The efficiency of solar wind (SW)- magnetosphere (MSPH) coupling-ideal magnetohydrodynamic (MHD) effects while the second term governs the ideal MHD conversion between magnetic and kinetic (thermal and bulk flow) energy. In the ideal MHD limit a positive value of (~j � ~B) Á ~v corresponds

California at Berkeley, University of

174

Proceedings of the 23rd intersociety energy conversion engineering conference  

Microsoft Academic Search

These proceedings contain papers presented at the 23rd engineering conference on the subject of energy conversion. Specific papers include: mechanical energy storage; thermal energy storage; fuel cells; battery energy storage-terrestrial applications; space battery energy storage and superconductivity. In brief a review of different batteries and fuel cells design and applications is provided.

Goswami

1988-01-01

175

A Metric (SI) Energy Scale: Conversions and Comparisons  

ERIC Educational Resources Information Center

An energy scale, constructed in terms of the Joule, is presented. It provides for the conversion of all traditional units employed in engineering, science, and technology to describe forms of energy; gives the energy associated with physical phenomena; and provides energy equivalents of quantities associated with various energy sources. (DT)

Petrakis, L.

1974-01-01

176

Progress on PEP-II Magnet Power Conversion System?  

SciTech Connect

The various power systems for supplying the PEP-II DCmagnets rely exclusively on switch mode conversion, utilizing a varietyof means depending on the requirements. All of the larger power supplies,ranging from 10 to 200 kW, are powered from DC sources utilizingrectified 480 V AC. Choppers can be used for the series connectedstrings, but for smaller groups and individual magnets, inverters drivinghigh-frequency transformers with secondary rectifiers comprise the bestapproach. All of the various systems use a "building block" approach ofmultiple standard-size units connected in series or parallel to mostcost-effectively deal with a great range of voltage and currentrequirements. Utilization of existing infrastructure from PEP-I has beena cost-effective determinant. Equipment is being purchased eitheroff-the-shelf, through performance specification, or by hardware purchasebased on design-through-prototype. The corrector magnet power system,utilizing inexpensive, off-the-shelf four-quadrant switching motorcontrollers, has already proven very reliable: 120 of the total of 900units have been running on the injection system for four months with nofailures.

Bellomo, P.; Genova, L.; Jackson, T.; Shimer, D.

1996-06-01

177

Open cycle ocean thermal energy conversion system  

DOEpatents

An improved open cycle ocean thermal energy conversion system including a flash evaporator for vaporizing relatively warm ocean surface water and an axial flow, elastic fluid turbine having a vertical shaft and axis of rotation. The warm ocean water is transmitted to the evaporator through a first prestressed concrete skirt-conduit structure circumferentially situated about the axis of rotation. The unflashed warm ocean water exits the evaporator through a second prestressed concrete skirt-conduit structure located circumferentially about and radially within the first skirt-conduit structure. The radially inner surface of the second skirt conduit structure constitutes a cylinder which functions as the turbine's outer casing and obviates the need for a conventional outer housing. The turbine includes a radially enlarged disc element attached to the shaft for supporting at least one axial row of radially directed blades through which the steam is expanded. A prestressed concrete inner casing structure of the turbine has upstream and downstream portions respectively situated upstream and downstream from the disc element. The radially outer surfaces of the inner casing portions and radially outer periphery of the axially interposed disc cooperatively form a downwardly radially inwardly tapered surface. An annular steam flowpath of increasing flow area in the downward axial direction is radially bounded by the inner and outer prestressed concrete casing structures. The inner casing portions each include a transversely situated prestressed concrete circular wall for rotatably supporting the turbine shaft and associated structure. The turbine blades are substantially radially coextensive with the steam flowpath and receive steam from the evaporator through an annular array of prestressed concrete stationary vanes which extend between the inner and outer casings to provide structural support therefor and impart a desired flow direction to the steam.

Wittig, J. Michael (West Goshen, PA)

1980-01-01

178

Mutual conversion between electromagnetic and ultrasonic waves in high- T c superconductors under magnetic field  

Microsoft Academic Search

An RF magnetic field applied parallel to the external DC magnetic field in the superconducting YBa2Cu3O7 generates a longitudinal ultrasonic wave. Conversely, the longitudinal ultrasonic wave induces the RF field. The conversion at the lower-temperature region is explained in terms of the vibration of pinned vortices in the linear regime.

Hideki Haneda; Takehiko Ishiguro; Masato Murakami

1996-01-01

179

FRONTIERS ARTICLE Fundamentals of energy transport, energy conversion, and thermal properties  

E-print Network

FRONTIERS ARTICLE Fundamentals of energy transport, energy conversion, and thermal properties, thermoelectrics, and photovoltaics. However, energy transport and conversion, at the organic­inorganic interface and as an energy conversion technology. Aviram and Ratner's revolutionary suggestion that molecules could behave

Malen, Jonathan A.

180

Potassium plasma cell facilitates thermionic energy conversion process  

NASA Technical Reports Server (NTRS)

Thermionic energy converter converts nuclear generated heat directly into high frequency and direct current output. It consists of a potassium plasma cell, a tantalum emitter, and a silver plated copper collector. This conversion process eliminates the steam interface usually required between the atomic heat source and the electrical conversion system.

Richards, H. K.

1967-01-01

181

Proceedings of the 25th intersociety energy conversion engineering conference  

Microsoft Academic Search

This book presents the proceedings of a conference on energy conversion engineering. The authors report on environmental effects, computer simulations, and thermal management of aerospace power systems. Papers on conversion technologies are presented, covering heat engines and advanced cycles, heat pumps, and magnethydrodynamics.

P. A. Nelson; W. W. Schertz; R. H. Till

1990-01-01

182

Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system  

DOEpatents

This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.

Dziendziel, Randolph J. (Middle Grove, NY); DePoy, David Moore (Clifton Park, NY); Baldasaro, Paul Francis (Clifton Park, NY)

2007-01-23

183

Semiconductor nanowires for photovoltaic and photoelectrochemical energy conversion  

SciTech Connect

Semiconductor nanowires (NW) possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for wide-scale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional (1D) structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.

Dasgupta, Neil; Yang, Peidong

2013-01-23

184

Analysis of a direct energy conversion system using medium energy helium ions  

E-print Network

A scaled direct energy conversion device was built to convert kinetic energy of singly ionized helium ions into an electric potential by the process of direct conversion. The experiments in this paper aimed to achieve higher potentials and higher...

Carter, Jesse James

2006-08-16

185

A review of ocean wave energy conversion systems  

Microsoft Academic Search

The start of the new millennium has been co-incident with an energy crisis. With the price of energy increasing and concerns about environmental damages as a result of using fossil fuels, there is a growing attention toward utilization of renewable energy sources. In particular, ocean energy conversion has been of interest for many years. In this paper, different types of

R. Sabzehgar; M. Moallem

2009-01-01

186

Potential methods and perspectives of solar energy conversion via photocatalytic processes. [345 references  

Microsoft Academic Search

Existing methods of solar energy conversion are classified into 4 types: (1) thermal; (2) photophysical; (3) photochemical (including photoelectrolysis); and (4) photobiological (based on natural photosynthesis). Thermal conversion under direct conditions is an attractive method of conversion, but further conversion of heat into mechanical or electrical energy make thermal conversion seem unsuitable for large-scale use. Methods based on direct conversion

K. I. Zamaraev; V. N. Parmon

1980-01-01

187

Proceedings of the 23rd intersociety energy conversion engineering conference  

Microsoft Academic Search

This book covers the proceedings of the 23rd Interscociety Energy Conversion Engineering Conference. The subjects covered here are: Stirling engines, heat engines, thermoelectric power, thermal rejection systems, advanced cycles and systems, nuclear power, and thermionic power.

Goswami

1988-01-01

188

Towards improved photovoltaic conversion using dilute magnetic semiconductors (abstract only).  

PubMed

Present photovoltaic devices, based on p/n junctions, are limited from first principles to maximal efficiencies of 31% (40% under full solar concentration; Shockley and Queisser 1961 J. Appl. Phys. 32 510). However, more innovative schemes may overcome the Shockley-Queisser limit since the theoretical maximal efficiency of solar energy conversion is higher than 85% (Harder and Würfel 2003 Semicond. Sci. Technol. 18 S151). To date, the only practical realization of such an innovative scheme has been multi-junction devices, which at present hold the world record for efficiency at nearly 41% at significant solar concentration (US DOE news site: http://www.energy.gov/news/4503.htm). It has been proposed that one could make use of the solar spectrum in much the same way as the multi-junction devices do but in a single cell, using impurity induced intermediate levels to create gaps of different sizes. This intermediate level semiconductor (ILSC) concept (Green and Wenham 1994 Appl. Phys. Lett. 65 2907; Luque and Martí1997 Phys. Rev. Lett. 78 5014) has a maximal efficiency similar to that of multi-junction devices but suffers from prohibitively large non-radiative recombination rates. We here propose to use a ferromagnetic impurity scheme in order to reduce the non-radiative recombination rates while maintaining the high theoretical maximum efficiency of the ILSC scheme, that is about 46%. Using density functional theory calculations, the electronic and energetic properties of transition metal impurities for a wide range of semiconductors have been analysed. Of the several hundred compounds studied, only a few fulfil the design criteria that we present here. As an example, wide gap AlP is one of the most promising compounds. It was found that inclusion of significant amounts of Mn in AlP induces band structures providing conversion efficiencies potentially close to the theoretical maximum, with an estimated Curie temperature reaching above 100 K. PMID:21693888

Olsson, Pär; Guillemoles, J-F; Domain, C

2008-02-13

189

Cluster Observations of Energy Conversion Regions in the Plasma Sheet  

Microsoft Academic Search

\\u000a Cluster allows for the first time a systematic examination of energy conversion, by the evaluation of the power density, E · J, with E the electric field and J the current density. Following a careful inspection of the Cluster plasma sheet data from the summer and fall of 2001, we\\u000a selected 43 energy conversion regions (ECRs), out of which 26

O. Marghitu; M. Hamrin; B. Klecker; K. Rönnmark; S. Buchert; L. M. Kistler; M. André; H. Rème

2010-01-01

190

A summary of USSR thermionic energy conversion activity  

NASA Technical Reports Server (NTRS)

The paper surveys the research and development associated with thermionic energy conversion in the USSR. Consideration is given to the basic physics of the thermionic converter, the development of thermionic nuclear reactors including the three TOPAZ models, radioisotope-heated generators, and the thermionic topping of fossil-fueled electric-power plants. Comparisons are made between U.S. and USSR capabilities in thermionic energy conversion and potential cooperative programs are noted.

Rasor, N. S.

1978-01-01

191

Space electric power design study. [laser energy conversion  

NASA Technical Reports Server (NTRS)

The conversion of laser energy to electrical energy is discussed. Heat engines in which the laser heats the gas inside the engine through a window as well as heat engines in which the gas is heated by a thermal energy storage reservoir which has been heated by laser radiation are both evaluated, as well as the necessary energy storage, transmission and conversion components needed for a full system. Preliminary system concepts are presented and a recommended development program is outlined. It appears possible that a free displacer Stirling engine operating directly a linear electric generator can convert 65% of the incident laser energy into electricity.

Martini, W. R.

1976-01-01

192

Energy conversion device with support member having pore channels  

DOEpatents

Energy devices such as energy conversion devices and energy storage devices and methods for the manufacture of such devices. The devices include a support member having an array of pore channels having a small average pore channel diameter and having a pore channel length. Material layers that may include energy conversion materials and conductive materials are coaxially disposed within the pore channels to form material rods having a relatively small cross-section and a relatively long length. By varying the structure of the materials in the pore channels, various energy devices can be fabricated, such as photovoltaic (PV) devices, radiation detectors, capacitors, batteries and the like.

Routkevitch, Dmitri [Longmont, CO; Wind, Rikard A [Johnstown, CO

2014-01-07

193

Superconducting energy storage magnet  

NASA Technical Reports Server (NTRS)

A superconducting magnet is formed having composite conductors arrayed in coils having turns which lie on a surface defining substantially a frustum of a cone. The conical angle with respect to the central axis is preferably selected such that the magnetic pressure on the coil at the widest portion of the cone is substantially zero. The magnet structure is adapted for use as an energy storage magnet mounted in an earthen trench or tunnel where the strength the surrounding soil is lower at the top of the trench or tunnel than at the bottom. The composite conductor may be formed having a ripple shape to minimize stresses during charge up and discharge and has a shape for each ripple selected such that the conductor undergoes a minimum amount of bending during the charge and discharge cycle. By minimizing bending, the working of the normal conductor in the composite conductor is minimized, thereby reducing the increase in resistance of the normal conductor that occurs over time as the conductor undergoes bending during numerous charge and discharge cycles.

Boom, Roger W. (Inventor); Eyssa, Yehia M. (Inventor); Abdelsalam, Mostafa K. (Inventor); Huang, Xianrui (Inventor)

1993-01-01

194

Energy production from biomass (Part 2): Conversion technologies.  

PubMed

The use of biomass to provide energy has been fundamental to the development of civilisation. In recent times pressures on the global environment have led to calls for an increased use of renewable energy sources, in lieu of fossil fuels. Biomass is one potential source of renewable energy and the conversion of plant material into a suitable form of energy, usually electricity or as a fuel for an internal combustion engine, can be achieved using a number of different routes, each with specific pros and cons. A brief review of the main conversion processes is presented, with specific regard to the production of a fuel suitable for spark ignition gas engines. PMID:12058830

McKendry, Peter

2002-05-01

195

Proceedings of the 25th intersociety energy conversion engineering conference  

Microsoft Academic Search

This book contains the proceedings of the 25th intersociety energy conversion engineering conference, Volume 4. Topics covered include: Thermal management, Transportation, Advanced sulfur control strategies for coal, Needs and (some) solutions for integrated environmental controls, Systems solutions for energy\\/environmental conflicts, Control systems, motor\\/generators and flywheels in energy storage, Advanced phase change media for thermal energy storage, Thermal energy storage systems

P. A. Nelson; W. W. Schertz; R. H. Till

1990-01-01

196

Energy Conversion and Storage Program: 1992 Annual report  

SciTech Connect

This report is the 1992 annual progress report for the Energy Conversion and Storage Program, a part of the Energy and Environment Division of the Lawrence Berkeley Laboratory. Work described falls into three broad areas: electrochemistry; chemical applications; and materials applications. The Energy Conversion and Storage Program applies principles of chemistry and materials science to solve problems in several areas: (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes and chemical species, and (5) study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Chemical applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing product and waste streams from synfuel plants, coal gasifiers, and biomass conversion processes. Materials applications research includes evaluation of the properties of advanced materials, as well as development of novel preparation techniques. For example, techniques such as sputtering, laser ablation, and poised laser deposition are being used to produce high-temperature superconducting films.

Cairns, E.J.

1993-06-01

197

Ocean Thermal Energy Conversion (OTEC) A New Secure Renewable Energy Source  

E-print Network

Ocean Thermal Energy Conversion (OTEC) A New Secure Renewable Energy Source For Defense Water Temperature Delta 2 A New Clean Renewable 24/7 Energy Source #12;Ocean Thermal Energy Conversion and Commercial Applications 1 Dr. Ted Johnson Director of Alternative Energy Programs Development Lockheed Martin

198

Journal of Power Sources 156 (2006) 677684 Thermodynamic analysis of electrokinetic energy conversion  

E-print Network

conversion Xiangchun Xuan, Dongqing Li Department of Mechanical and Industrial Engineering, University is carried out for electrokinetic energy conversion. We demonstrate that the efficiencies depend solely Elsevier B.V. All rights reserved. Keywords: Electrokinetic energy conversion; Generator; Pump; Figure

Xuan, Xiangchun "Schwann"

199

Advanced thermionic energy conversion: Joint highlights  

NASA Technical Reports Server (NTRS)

A theoretical model was used to study the effects of structured electrodes on converter I-V characteristics and results are given. An auxiliary-ion-source triode operated as a plasmatron was used for studying the enhancement distribution and magnetic effects, and results are reported. Design features of the high current-zero power (ZEPO) converter tests are given.

1976-01-01

200

Superconducting magnetic energy storage  

SciTech Connect

Recent programmatic developments in Superconducting Magnetic Energy Storage (SMES) have prompted renewed and widespread interest in this field. In mid 1987 the Defense Nuclear Agency, acting for the Strategic Defense Initiative Office, issued a request for proposals for the design and construction of SMES Engineering Test Model (ETM). Two teams, one led by Bechtel and the other by Ebasco, are now engaged in the first phase of the development of a 10 to 20 MWhr ETM. This report presents the rationale for energy storage on utility systems, describes the general technology of SMES, and explains the chronological development of the technology. The present ETM program is outlined; details of the two projects for ETM development are described in other papers in these proceedings. The impact of high T/sub c/ materials on SMES is discussed. 69 refs., 3 figs., 3 tabs.

Hassenzahl, W.

1988-08-01

201

Cogeneration Technology Alternatives Study (CTAS). Volume 4: Energy conversion systems  

NASA Technical Reports Server (NTRS)

Industrial processes from the largest energy consuming sectors were used as a basis for matching a similar number of energy conversion systems that are considered as candidate which can be made available by the 1985 to 2000 time period. The sectors considered included food, textiles, lumber, paper, chemicals, petroleum, glass, and primary metals. The energy conversion systems included steam and gas turbines, diesels, thermionics, stirling, closed-cycle and steam injected gas turbines, and fuel cells. Fuels considered were coal, both coal and petroleum-based residual and distillate liquid fuels, and low Btu gas obtained through the on-site gasification of coal. An attempt was made to use consistent assumptions and a consistent set of ground rules specified by NASA for determining performance and cost. The advanced and commercially available cogeneration energy conversion systems studied in CTAS are fined together with their performance, capital costs, and the research and developments required to bring them to this level of performance.

Brown, D. H.; Gerlaugh, H. E.; Priestley, R. R.

1980-01-01

202

Preliminary results on the conversion of laser energy into electricity  

NASA Technical Reports Server (NTRS)

A preliminary experiment was performed to investigate conversion of 10.6 micron laser energy to electrical energy via a laser-sustained argon plasma. Short-circuit currents of 0.7 A were measured between a thoriated-tungsten emitter and collector electrodes immersed in the laser-sustained argon plasma. Open-circuit voltages of about 1.5 V were inferred from the current-voltage load characteristics. The dominant mechanism of laser energy conversion is uncertain at this time. Much higher output powers appear possible.

Thompson, R. W.; Manista, E. J.; Alger, D. L.

1978-01-01

203

A modified Wells turbine for wave energy conversion  

Microsoft Academic Search

The method of wave energy conversion utilises an oscillating water column (OWC). The OWC converts wave energy into low-pressure pneumatic energy in the form of bi-directional airflow. Wells turbine with its zero blade pitch setting has been used to convert this pneumatic power into uni-directional mechanical shaft power. Measurements in OWC based wave energy plants in India and Japan show

T. Setoguchi; S. Santhakumar; M. Takao; T. H. Kim; K. Kaneko

2003-01-01

204

ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis project  

Microsoft Academic Search

The Annual Report presents the fiscal year (FY) 1988 research activities and accomplishments, for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division. The ECUT Biocatalysis Project is managed by the Jet Propulsion Laboratory, California Institute of Technology. The Biocatalysis Project is a mission-oriented, applied research and exploratory development activity directed toward resolution

Larry Baresi

1989-01-01

205

Wind Energy Conversion Systems. A Unit of Instruction.  

ERIC Educational Resources Information Center

The number of secondary schools, colleges, and universities offering courses in wind energy machine construction, repair, and installation, continues to increase. It is the purpose of this unit to include the study of wind energy conversion systems (WECS) as an integral part of related vocational and technical curriculum materials. The unit's…

Greenwald, Martin

206

Wind Energy Conversion Systems Fault Diagnosis Using Wavelet Analysis  

E-print Network

Wind Energy Conversion Systems Fault Diagnosis Using Wavelet Analysis Elie Al-Ahmar1,2 , Mohamed El transient technique suitable for electrical and mechanical failure diagnosis in an induction generator based, induction generator, Discrete Wavelet Transform (DWT), failure diagnosis. I. Introduction Wind energy

Paris-Sud XI, Université de

207

Nanostructured materials for advanced energy conversion and storage devices  

Microsoft Academic Search

New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. This review describes some recent developments

Antonino Salvatore Aricò; Peter Bruce; Bruno Scrosati; Jean-Marie Tarascon; Walter van Schalkwijk

2005-01-01

208

High-Speed Liquid Projectiles: an Efficient Energy Conversion Tool  

Microsoft Academic Search

Application of high speed liquid projectiles for enhancement of the efficiency and reduction of the emission of fuel combustion is discussed. Overall energy efficiency of combustion can be improved if combustion products generated at an extreme high rate are used as a working fluid in material processing or energy conversion operations. In the course of a performed study the products

Ernest S. Geskin

2008-01-01

209

Energy conversion of fully random thermal relaxation times Franois Barriquand  

E-print Network

1 Energy conversion of fully random thermal relaxation times François Barriquand proba5050@hotmail.com ABSTRACT. Thermodynamic random processes in thermal systems are generally associated with one or several relaxation times, the inverse of which are formally homogeneous with energy. Here, we show in a precise way

Paris-Sud XI, Université de

210

Ocean Thermal Energy Conversion (OTEC): Ocean Engineering Technology Development  

Microsoft Academic Search

Ocean Thermal Energy Conversion (OTEC) is the principal ocean energy source under development in the U.S. because of its potential, state of development, and availability and access of the resource to the U.S. The major features of OTEC are that the source is renewable with minimum impact on the environment and the constant availability of the resource enhances OTEC acceptability

J. Giannotti; J. Vadus

1981-01-01

211

Proceedings of the 23rd intersociety energy conversion engineering conference  

Microsoft Academic Search

These proceedings collect papers given at a conference on energy conversion technologies. Topics include: coal-fired MHD generators; biomass gasifyers; waste product utilization and pyrolysis; refuse-derived fuels, anaerobic digestion, catalytic cracking, coal slurries, and fuel alcohol; waste heat utilization, heat pipes and heat pumps; evaporative cooling; wind turbines; photovoltaic power; electric vehicles; solar energy, collectors, receivers, water heaters, and space heaters;

Goswami

1988-01-01

212

Status of wind-energy conversion  

NASA Technical Reports Server (NTRS)

The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems; a sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to: (1) fossil fuel systems; (2) hydroelectric systems; or (3) dispersing them throughout a large grid network. Wind energy appears to have the potential to meet a significant amount of our energy needs.

Thomas, R. L.; Savino, J. M.

1973-01-01

213

Thermionic emission energy distribution from nanocrystalline diamond films for direct thermal-electrical energy conversion applications  

Microsoft Academic Search

In the ongoing quest for energy production by nonconventional methods, energy conversion by vacuum and solid-state thermionic emission devices is one of the potentially efficient pathways for converting thermal energy directly into electrical power. The realization of practical of thermionic energy conversion devices strongly depends on achieving low work function materials, which is thus far a limiting factor. In an

Kishore Uppireddi; Tyler L. Westover; Timothy S. Fisher; Brad R. Weiner; Gerardo Morell

2009-01-01

214

Energy Conversion, Mixing Energy, and Neutral Surfaces with a Nonlinear Equation of State  

E-print Network

Energy Conversion, Mixing Energy, and Neutral Surfaces with a Nonlinear Equation of State JONAS energy, it is generally assumed that it does not produce a restoring buoyancy force. However, it is here effect) such a neutral displacement is accompanied by a conversion between internal energy E

Nycander, Jonas

215

Energy Conversion Efficiency of Nanofluidic Batteries: Hydrodynamic Slip and Access Resistance  

E-print Network

Energy Conversion Efficiency of Nanofluidic Batteries: Hydrodynamic Slip and Access Resistance Yu and concentration polarization) on the energy conversion efficiency of pressure-driven electrolyte flow through battery system is its low energy conversion efficiency. Up to now, the energy conversion efficiencies have

Chang, Hsueh-Chia

216

Solar energy conversion via hot electron internal photoemission in metallic nanostructures: Efficiency estimates  

E-print Network

Solar energy conversion via hot electron internal photoemission in metallic nanostructures://scitation.aip.org/termsconditions. Downloaded to ] IP: 131.215.44.236 On: Tue, 01 Apr 2014 22:46:10 #12;Solar energy conversion via hot electron for the construction of solar energy-conversion devices. Herein, we evaluate theoretically the energy-conversion

Atwater, Harry

217

Energy Conversion and Storage Program. 1990 annual report  

SciTech Connect

The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

Cairns, E.J.

1992-03-01

218

Magnetopause reconnection and energy conversion as influenced by the dipole tilt and the IMF Bx  

NASA Astrophysics Data System (ADS)

We study the effect of Earth's dipole tilt angle and interplanetary magnetic field (IMF) Bx and By components on the location of reconnection and the energy conversion at the magnetopause. We simulate southward IMF satisfying both inward- and outward-type Parker spiral conditions during three different dipole tilt angles using a global magnetohydrodynamic model GUMICS-4. We find that positive (negative) Bx contributes to the magnetopause reconnection line location by moving northward (southward) and positive (negative) dipole tilt angle by moving it southward (northward). The tilt shifts the dayside load region toward the winter hemisphere and the summer cusp toward the equatorial plane. Magnetic flux hence piles effectively in the summer hemisphere leading to increased magnetopause currents that enhance the Poynting flux through the magnetopause. We find that the intensity of the energy conversion in the generators is strongly affected by the dipole tilt angle, whereas intensity in the load region is mainly affected by IMF Bx.

Hoilijoki, Sanni; Souza, Vitor M.; Walsh, Brian M.; Janhunen, Pekka; Palmroth, Minna

2014-06-01

219

Primary Photosynthetic Energy Conversion in Bacterial Reaction Centers  

NASA Astrophysics Data System (ADS)

The development of human societies is strongly influenced by the available energetic resources. In a period where the limitations of conventional fossil energy carriers become as evident as the often uncontrollable dangers of nuclear energy, one has to reconsider regenerative energy resources. Here photovoltaic or photochemical use of solar energy is an important approach. Since the early days of evolution some two billion years ago, the dominant energetic input into the life system on earth occurs via the conversion of solar energy performed in photosynthetic organisms. The fossil energy carriers that we use and waste today have been produced by photosynthesis over millions of years. In the race for an extended and versatile use of solar energy, semiconductorbased photovoltaic devices have been developed. However, even after decades of intense engineering they cannot serve as a competitive alternative to fossil energy. Under these circumstances new alternatives are required. One line of scientific development may use the operational principles of photosynthesis since photosynthesis is still our main energy source. In this respect, we will present results on the basic concepts of energy conversion in photosynthetic bacteria, which could be used as a guideline to alternative light energy conversion systems.

Zinth, Wolfgang; Wachtveitl, J.

220

Polymer Based Nanocomposites for Solar Energy Conversion  

SciTech Connect

Organic semiconductor-based photovoltaic devices offer the promise of low cost photovoltaic technology that can be manufactured via large-scale, roll-to-roll printing techniques. Existing organic photovoltaic devices are currently limited to solar power conversion efficiencies of 3?5%. This is because of poor overlap between the absorption spectrum of the organic chromophores and the solar spectrum, non-ideal band alignment between the donor and acceptor species, and low charge carrier mobilities. To address these issues, we are investigating the development of dendrimeric organic semiconductors that are readily synthesized with high purity. They also benefit from optoelectronic properties, such as band gap and band positions, which can be easily tuned by substituting different chemical groups into the molecule. Additionally, we are developing nanostructured oxide/conjugated polymer composite photovoltaics. These composites take advantage of the high electron mobilities attainable in oxide semiconductors and can be fabricated using low-temperature solution-based growth techniques. Here, we discuss the synthesis and preliminary device results of these novel materials and composites.

Shaheen, S.; Olson, D.; White, M.; Mitchell, W.; Miedaner, A.; Curtis, C.; Rumbles, G.; Gregg, B.; Ginley, D.

2005-01-01

221

Status of wind-energy conversion  

NASA Technical Reports Server (NTRS)

The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems. A sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short-term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to fossil fuel systems, hydroelectric systems, or dispersing them throughout a large grid network. The NSF and NASA-Lewis Research Center have sponsored programs for the utilization of wind energy.

Thomas, R. L.; Savino, J. M.

1973-01-01

222

Vibration-to-electric energy conversion  

Microsoft Academic Search

A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low-power electronic systems. The energy is transduced through the use of a variable capacitor, which has been designed with MEMS (microelectromechanical systems) tech- nology. A low-power controller IC has been fabricated in a 0 6µm CMOS pro- cess and has been tested and

Scott Meninger; Jose Oscar Mur-Miranda; Rajeevan Amirtharajah; Anantha Chandrakasan; Jeffrey Lang

1999-01-01

223

Vibration-to-electric energy conversion  

Microsoft Academic Search

Abstract: A system is proposed to convert ambient mechanicalvibration into electrical energy for use in powering autonomouslow power electronic systems. The energy is transduced throughthe use of a variable capacitor. Using microelectromechanical systems(MEMS) technology, such a device has been designed for thesystem. A low-power controller IC has been fabricated in a 0.6- mCMOS process and has been tested and measured

Scott Meninger; Jose Oscar Mur-miranda; Rajeevan Amirtharajah; Anantha P. Chandrakasan; Jeffrey H. Lang

2001-01-01

224

Supramolecular Structures for Photochemical Energy Conversion  

SciTech Connect

OAK B188 The goal of this project is to mimic the energy transduction processes by which photosynthetic organisms harvest sunlight and convert it to forms of energy that are more easily used and stored. The results may lead to new technologies for solar energy harvesting based on the natural photosynthetic process. They may also enrich our understanding and control of photosynthesis in living organisms, and lead to methods for increasing natural biomass production, carbon dioxide removal, and oxygen generation. In our work to date, we have learned how to make synthetic antenna and reaction center molecules that absorb light and undergo photoinduced electron transfer to generate long-lived, energetic charge-separated states. We have assembled a prototype system in which artificial reaction centers are inserted into liposomes (artificial cell-like constructs), where they carry out light-driven transmembrane translocation of hydrogen ions to generate proton motive force. By insertion of natural ATP synthase into the liposomal bilayer, this proton motive force has been used to power the synthesis of ATP. ATP is a natural biological energy currency. We are carrying out a systematic investigation of these artificial photosynthetic energy harvesting constructs in order to understand better how they operate. In addition, we are exploring strategies for reversing the direction of the light-powered proton pumping. Most recently, we have extended these studies to develop a light-powered transmembrane calcium ion pump that converts sunlight into energy stored as a calcium ion concentration gradient across a lipid bilayer.

Gust, Devens; Moore, Thomas A.; Moore, Ana L.

2003-08-26

225

A Novel Control Scheme for Current-Source-Converter-Based PMSG Wind Energy Conversion Systems  

Microsoft Academic Search

A novel control scheme for permanent-magnet synchronous generator is proposed in this paper, where a current-source converter is employed as the bridge between the generator and the grid for high-power wind energy conversion systems. In these medium voltage (2.3-13.8 kV) level applications, current-source converters not only have inherent advantages, but also present some challenges for controller design due to the

Jingya Dai; Bin Wu

2009-01-01

226

Effects of semiconduction on electromechanical energy conversion in piezoelectrics  

NASA Astrophysics Data System (ADS)

We study the effect of semiconduction on mechanical-to-electrical energy conversion through a theoretical analysis on the thickness-extensional vibration of a piezoelectric semiconductor plate driven mechanically. An analytical solution is obtained. A ZnO plate is used as a numerical example. Results show that both the electrical output power and the energy conversion efficiency are sensitive to semiconduction at a moderate carrier density of 1015 m?3, and that the effect of the dissipation due to semiconduction can be comparable to the effect of material damping when the material quality factor is in the usual range of 102–103.

Li, Peng; Jin, Feng; Yang, Jiashi

2015-02-01

227

Photoassisted electrolysis of water - Conversion of optical to chemical energy  

NASA Technical Reports Server (NTRS)

A description is given of devices, termed photoelectrochemical cells, which can, in principle, be used to directly convert light to fuels and/or electricity. The fundamental principles on which the photoelectrochemical cell is based are related to the observation that irradiation of a semiconductor electrode in an electrochemical cell can result in the flow of an electric current in the external circuit. Attention is given to the basic mechanisms involved, the energy conversion efficiency, the advantages of photoelectrochemical cells, and the results of investigations related to the study of energy conversion via photoelectrochemical cells.

Wrighton, M. S.; Bolts, J. M.; Kaiser, S. W.; Ellis, A. B.

1976-01-01

228

Porous media for catalytic renewable energy conversion  

NASA Astrophysics Data System (ADS)

A novel flow-based method is presented to place catalytic nanoparticles into a reactor by sol-gelation of a porous ceramic consisting of copper-based nanoparticles, silica sand, ceramic binder, and a gelation agent. This method allows for the placement of a liquid precursor containing the catalyst into the final reactor geometry without the need of impregnating or coating of a substrate with the catalytic material. The so generated foam-like porous ceramic shows properties highly appropriate for use as catalytic reactor material, e.g., reasonable pressure drop due to its porosity, high thermal and catalytic stability, and excellent catalytic behavior. The catalytic activity of micro-reactors containing this foam-like ceramic is tested in terms of their ability to convert alcoholic biofuel (e.g. methanol) to a hydrogen-rich gas mixture with low concentrations of carbon monoxide (up to 75% hydrogen content and less than 0.2% CO, for the case of methanol). This gas mixture is subsequently used in a low-temperature fuel cell, converting the hydrogen directly to electricity. A low concentration of CO is crucial to avoid poisoning of the fuel cell catalyst. Since conventional Polymer Electrolyte Membrane (PEM) fuel cells require CO concentrations far below 100 ppm and since most methods to reduce the mole fraction of CO (such as Preferential Oxidation or PROX) have CO conversions of up to 99%, the alcohol fuel reformer has to achieve initial CO mole fractions significantly below 1%. The catalyst and the porous ceramic reactor of the present study can successfully fulfill this requirement.

Hotz, Nico

2012-05-01

229

The plasmatron: Advanced mode thermionic energy conversion  

NASA Technical Reports Server (NTRS)

A theory of the plasmatron was developed. Also, a wide range of measurements were obtained with two versatile, research devices. To gain insight into plasmatron performance, the experimental results are compared with calculations based on the theoretical model of plasmatron operation. Results are presented which show that the plasma arc drop of the conventional arc (ignited) mode converter can be suppressed by use of an auxiliary ion source. The improved performance, however, is presently limited to low current densities because of voltage losses due to plasma resistance. This resistance loss could be suppressed by an increase in the plasma electron temperature or a decrease in spacing. Plasmatron performance characteristics for both argon and cesium are reported. The argon plasmatron has superior performance. Results are also presented for magnetic cutoff effects and for current distributing effects. These are shown to be important factors for the design of practical devices.

Hansen, L. K.; Hatch, G. L.; Rasor, N. S.

1976-01-01

230

Low to high temperature energy conversion system  

NASA Technical Reports Server (NTRS)

A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.

Miller, C. G. (inventor)

1977-01-01

231

Energy Conversion: Solid-State Lighting  

E-print Network

;232 Computational Approaches to Energy Materials range. A variation is the halogen lamp, which contains a mix is made of a fluorescent tube that con- tains an inert gas and small amounts of mercury. As the electric-state lighting based on light-emitting diodes (LEDs) is a promising recent development and has the potential

232

Conversion of acoustic energy by lossless liners  

NASA Technical Reports Server (NTRS)

The Blokhintzev acoustic energy equation is applied to a two-dimensional duct containing a uniform flow with a finite length lining. It is shown that the difference of the incident and outgoing acoustic energy differs in general from the energy dissipated in the liner, the difference being related to the displacements at the liner's edges. It is shown that in the case of a locally reacting lossless liner for frequencies below the first cut-off frequency and for low Mach number acoustic energy is generated if the flow and the incident sound wave are in the same direction and is absorbed if these two directions are opposite unless special edge conditions are met. Furthermore it is shown under the same conditions that the ratio of the reflection coefficient at finite flow velocity to the reflection coefficient at vanishing velocity is to first order in Mach number independent of the liner characteristics. A numerical calculation confirms these predictions at least for mass-like linear admittance.

Moehring, W.; Eversman, W.

1982-01-01

233

Magnetic energy storage  

SciTech Connect

The fusion program embraces low loss superconductor strand development with integration into cables capable of carrying 50 kA in pulsed mode at high fields. This evolvement has been paralleled with pulsed energy storage coil development and testing from tens of kJ at low fields to a 20 MJ prototype tokamak induction coil at 7.5 T. Energy transfer times have ranged from 0.7 ms to several seconds. Electric utility magnetic storage for prospective application is for diurnal load leveling with massive systems to store 10 GWh at 1.8 K in a dewar structure supported on bedrock underground. An immediate utility application is a 30 MJ system to be used to damp power oscillations on the Bonneville Power Administration electric transmission lines. An off-shoot of this last work is a new program for electric utility VAR control with the potential for use to suppress subsynchronous resonance. This paper presents work in progress, work planned, and recently completed unusual work.

Rogers, J.D.

1980-01-01

234

Proceedings of the 25th intersociety energy conversion engineering conference  

SciTech Connect

This book contains the proceedings of the 25th Intersociety Energy Conversion Engineering Conference. Volume 5 is organized under the following headings: Photovoltaics I, Photovoltaics II, Geothermal power, Thermochemical conversion of biomass, Energy from waste and biomass, Solar thermal systems for environmental applications, Solar thermal low temperature systems and components, Solar thermal high temperature systems and components, Wind systems, Space power sterling technology Stirling cooler developments, Stirling solar terrestrial I, Stirling solar terrestrial II, Stirling engine generator sets, Stirling models and simulations, Stirling engine analysis, Stirling models and simulations, Stirling engine analysis, Stirling engine loss understanding, Novel engine concepts, Coal conversion and utilization, Power cycles, MHD water propulsion I, Underwater vehicle powerplants - performance, MHD underwater propulsion II, Nuclear power, Update of advanced nuclear power reactor concepts.

Nelson, P.A.; Schertz, W.W.; Till, R.H.

1990-01-01

235

Energy conversion in Purple Bacteria Photosynthesis  

E-print Network

The study of how photosynthetic organisms convert light offers insight not only into nature's evolutionary process, but may also give clues as to how best to design and manipulate artificial photosynthetic systems -- and also how far we can drive natural photosynthetic systems beyond normal operating conditions, so that they can harvest energy for us under otherwise extreme conditions. In addition to its interest from a basic scientific perspective, therefore, the goal to develop a deep quantitative understanding of photosynthesis offers the potential payoff of enhancing our current arsenal of alternative energy sources for the future. In the following Chapter, we consider the trade-off between dynamics, structure and function of light harvesting membranes in Rps. Photometricum purple bacteria, as a model to highlight the priorities that arise when photosynthetic organisms adapt to deal with the ever-changing natural environment conditions.

Caycedo-Soler, Felipe; Quiroga, Luis; Zhao, Guannan; Johnson, Neil F

2011-01-01

236

Energy conversion in Purple Bacteria Photosynthesis  

E-print Network

The study of how photosynthetic organisms convert light offers insight not only into nature's evolutionary process, but may also give clues as to how best to design and manipulate artificial photosynthetic systems -- and also how far we can drive natural photosynthetic systems beyond normal operating conditions, so that they can harvest energy for us under otherwise extreme conditions. In addition to its interest from a basic scientific perspective, therefore, the goal to develop a deep quantitative understanding of photosynthesis offers the potential payoff of enhancing our current arsenal of alternative energy sources for the future. In the following Chapter, we consider the trade-off between dynamics, structure and function of light harvesting membranes in Rps. Photometricum purple bacteria, as a model to highlight the priorities that arise when photosynthetic organisms adapt to deal with the ever-changing natural environment conditions.

Felipe Caycedo-Soler; Ferney J. Rodriguez; Luis Quiroga; Guannan Zhao; Neil F. Johnson

2011-07-01

237

Light-energy conversion in engineered microorganisms.  

PubMed

Increasing interest in renewable resources by the energy and chemical industries has spurred new technologies both to capture solar energy and to develop biologically derived chemical feedstocks and fuels. Advances in molecular biology and metabolic engineering have provided new insights and techniques for increasing biomass and biohydrogen production, and recent efforts in synthetic biology have demonstrated that complex regulatory and metabolic networks can be designed and engineered in microorganisms. Here, we explore how light-driven processes may be incorporated into nonphotosynthetic microbes to boost metabolic capacity for the production of industrial and fine chemicals. Progress towards the introduction of light-driven proton pumping or anoxygenic photosynthesis into Escherichia coli to increase the efficiency of metabolically-engineered biosynthetic pathways is highlighted. PMID:18951642

Johnson, Ethan T; Schmidt-Dannert, Claudia

2008-12-01

238

Luminescent solar concentrators for energy conversion  

NASA Astrophysics Data System (ADS)

A description is given on the geographical, seasonal, and spectral distribution of terrestrial solar energy. The concept of nontracking fluorescent concentrators is discussed, together with the mathematical background for the collection and concentration of direct and diffuse light. Attention is also given to single plates, multiple stacks, and thin films doped by one or more colorants. An analysis is presented of the differences between inorganic and organic materials. In addition, suggestions are made for new hybrid systems.

Reisfeld, R.; Jorgensen, C. K.

1982-10-01

239

26th Intersociety Energy Conversion Engineering Conference  

Microsoft Academic Search

When individual pressure vessel (IPV) nickel-hydrogen (Ni\\/H2) cells were selected as the energy storage system for the Space Station Freedom in March of 1986, a limited database existed on life and performance characteristics of these cells in a low earth orbit (LEO) regime. Therefore, NASA LeRC initiated a Ni\\/H2 cell test program with the primary objectives of building a test

Frate

1991-01-01

240

Nanostructured semiconductors for thermoelectric energy conversion: Synthesis and transport properties  

NASA Astrophysics Data System (ADS)

Increasing energy demands and decreasing natural energy resources have sparked search for alternative clean and renewable energy sources. For instance, currently there is a tremendous interest in thermoelectric and photovoltaic solar energy production technologies. Half-Heusler (HH) alloys are among the most popular material systems presently under widespread investigations for high temperature thermoelectric energy conversion. Approaches to increase the thermoelectric figure of merit (ZT) of HH range from (1) chemical substitution of atoms with different masses within the same atomic position in the crystal structure to optimize carrier concentration and enhance phonon scattering via mass fluctuation and (2) embedding secondary phonon scattering centers in the matrix (nanostructuring) to further reduce thermal conductivity. This work focuses on three material systems. The first part describes the synthesis and properties (thermal conductivity, electrical conductivity, magnetic) of various oxide nanostructures (NiO, Co3O4) which were subsequently used as inclusion phases in a HH matrix to reduce the thermal conductivity. Detailed reviews of the past efforts along with the current effort to optimize synthetic routes are presented. The effects of the synthesis conditions on the thermoelectric properties of compacted pellets of NiO and Co3O4 are also discussed. The second part of the work discusses the development of synthetic strategies for the fabrication of p-type and n-type bulk nanostructured thermoelectric materials made of a half-Heusler matrix based on (Ti,Hf)CoSb, containing nanostructures with full-Heusler (FH) compositions and structures coherently embedded inside the half-Heusler matrix. The role of the nanostructures in the regulation of phonon and charge carrier transports within the half-heusler matrix is extensively discussed by combining transport data and electron microscopy images. It was found that the FH nanoinclusions form staggered heterojunctions with a valence band (VB) offset energy at the HH/FH phase boundaries. The resulting energy barrier discriminates existing holes with respect to their energy by trapping low energy holes, while promoting the transport of high energy holes through the VB of the FH-quantum dots. This "carrier culling" results in surprisingly large increase in the mobility and the effective mass of high energy holes contributing to electronic conduction. The simultaneous reduction in the density and the increase in the effective mass of holes resulted in large enhancements of the thermopower, whereas the increase in the mobility minimizes the drop in the electrical conductivity. In the third part, the application of this concept of nanostructuring on the Copper Selenide material system is described. Various synthetic approaches such as liquid assisted solid-state reaction and mechanical alloying are utilized for the fabrication of copper selenide compositions. We found that the mechanical alloying clearly decreases the thermal conductivity of the composition as well increases the Seebeck due to decrease in carrier concentrations.

Sahoo, Pranati

241

Thermal energy conversion system and method utilizing unencased expandites  

Microsoft Academic Search

A system and method of thermal energy conversion is disclosed. The method includes the steps of (A) providing a mass of unencased fluid expandite in a mass transport conduit circuit at a first combination of temperature and pressure; (B) introducing a thermal fluid into the mass transport conduit circuit from a source external to the mass transport conduit circuit at

1983-01-01

242

Calibration of sonic flowmeters for Ocean Thermal Energy Conversion (OTEC)  

Microsoft Academic Search

Scientists at the Naval Coastal Systems Center (NCSC) at Panama City, Florida, have used a commercially available acoustic flowmeter to monitor critical flow conditions during an OTEC (Ocean Thermal Energy Conversion) funded study of the effects of biofouling on the efficiency of a prototype heat transfer system. Flowmeters of this type are particularly useful in applications requiring unimpeded flow; i.e.,

D. F. Lott; G. G. Salsman; C. E. Hodges

1980-01-01

243

Investigation of direct solar-to-microwave energy conversion techniques  

Microsoft Academic Search

Identification of alternative methods of producing microwave energy from solar radiation for purposes of directing power to the Earth from space is investigated. Specifically, methods of conversion of optical radiation into microwave radiation by the most direct means are investigated. Approaches based on demonstrated device functioning and basic phenomenologies are developed. There is no system concept developed, that is competitive

N. E. Chatterton; T. K. Mookherji; P. K. Wunsch

1978-01-01

244

Efficiency evaluation of oxygen enrichment in energy conversion processes  

Microsoft Academic Search

The extent to which energy conversion efficiencies can be increased by using oxygen or oxygen-enriched air for combustion was studied. Combustion of most fuels with oxygen instead of air was found to have five advantages: increases combustion temperature and efficiency, improves heat transfer at high temperatures, reduces nitrous oxide emissions, permits a high ration of exhaust gas recirculation and allows

Bomelburg

1983-01-01

245

Solar Program Assessment: Environmental Factors - Ocean Thermal Energy Conversion.  

ERIC Educational Resources Information Center

This report presents the environmental problems which may arise with the further development of Ocean Thermal Energy Conversion, one of the eight Federally-funded solar technologies. To provide a background for this environmental analysis, the history and basic concepts of the technology are reviewed, as are its economic and resource requirements.…

Energy Research and Development Administration, Washington, DC. Div. of Solar Energy.

246

Limiting efficiencies for photovoltaic energy conversion in multigap systems  

Microsoft Academic Search

Multigap systems are better matched to the sun's spectrum than single gap systems and are, therefore, more efficient as photovoltaic converters. This paper reviews the different thermodynamic approaches used in the past for computing the limiting efficiency for the conversion of solar energy into work. Within this thermodynamic context, the limit ranges from 85.4% to 95.0% depending on the assumptions

Antonio Martí; Gerardo L. Araújo

1996-01-01

247

Wind energy conversion system simulator using variable speed induction motor  

Microsoft Academic Search

The conventional synchronous generator in wind energy conversion system are now getting replaced by variable speed induction generator to extract maximum power with wide range of wind speed limit. The design and performance of such system are required a simplified digital simulator, especially for development of optimal control solutions. The proposed work is to make a prototype of an variable

S. W. Mohod; M. V. Aware

2010-01-01

248

Electrode materials and processes for energy conversion and storage  

Microsoft Academic Search

This book contains 47 selections. Some of the titles are: Towards new materials in energy conversion; Monte Carlo simulation of the electrochemical faceting mechanism; Alternating current electrolysis at semiconductor electrodes; Materials for fuel cells, 1977-1997; Analysis and interpretation of AC impedance data for porous electrodes; and Fuel cells for extraterrestrial and terrestrial applications.

S. Srinivasan; S. Wagner; H. Wroblowa

1987-01-01

249

Proceedings of the 27th intersociety energy conversion engineering conference  

SciTech Connect

This book contains the proceedings of the 27th Intersociety Energy Conversion Engineering Conference. Topics included: Stirling Cycle Analysis; Stirling Cycle Models; Stirling Refrigerators/Heat Pumps and Cryocoolers; Domestic Policy; Efficiency/Conservation; Stirling Solar Terrestrial; Stirling Component Technology; Environmental Impacts; Renewable Resource Systems; Stirling Power Generation; Stirling Heat Transport System Technology; and Stirling Cycle Loss Understanding.

Not Available

1992-01-01

250

Chalmers University of Technology Henrik Thunman Department of Energy Conversion  

E-print Network

, having a heating value of 49.4MJ/kg Condensable hydrocarbons can be approximated by C6H6.2O0.2, having a heating value of 37MJ/kg #12;Chalmers University of Technology Henrik Thunman Department of Energy Conversion Heating Value of Volatiles devvolvolcharcharfuel charvol HHYHYH YY =-- =+1 Temperature Hchar 33MJ

251

Probabilistic production costing of diesel-wind energy conversion systems  

Microsoft Academic Search

This paper describes the development of a general probabilistic model of a diesel-wind energy conversion system (DWECS) composed of several diesel units, several wind turbines (wind farm), and battery storage feeding a load. The model allows the simulation of a diesel system with a wind farm of different wind turbine types considering system stability, and outages due to hardware failure

Sami H. Karaki; Riad B. Chedid; Rania Ramadan

2000-01-01

252

Probabilistic performance assessment of wind energy conversion systems  

Microsoft Academic Search

This paper describes the development of a general probabilistic model of an autonomous wind energy conversion system (WECS) composed of several wind turbines (wind farm) connected to a load and a battery storage. The proposed technique allows the simulation of wind farms containing identical or different wind turbines types and considers a bidirectional flow of power in and out of

S. H. Karaki; R. B. Chedid; R. Ramadan

1999-01-01

253

Intelligent control of a class of wind energy conversion systems  

Microsoft Academic Search

This paper discusses the control problem for a class of wind energy conversion systems (WECS). It first develops a detailed model and then compares four control algorithms based on conventional and intelligent control theories. A simple PI conventional controller for the exciter loop is carried out by using a first order model. When the system operating points change, the PI

R. Chedid; F. Mrad; M. Basma

1999-01-01

254

Geomagnetic activity effects on plasma sheet energy conversion  

Microsoft Academic Search

In this article we use three years (2001, 2002, and 2004) of Cluster plasma sheet data to investigate what happens to localized energy conversion regions (ECRs) in the plasma sheet during times of high magnetospheric activity. By examining variations in the power density, E·J, where E is the electric field and J is the current density obtained by Cluster, we

M. Hamrin; P. Norqvist; O. Marghitu; S. Buchert; B. Klecker; L. M. Kistler; I. Dandouras

2010-01-01

255

Role of Direct Energy Conversion in Engineering Curricula  

Microsoft Academic Search

The need to modernize and upgrade engineering curricula by introducing courses in direct energy conversion (DEC) at both graduate and undergraduate level is emphasized. It is suggested that an introductory coutse in DEC be initiated at the senior level. The inherently interdisciplinary nature and the scope of DEC are outlined. Partial lists of research and seminar projects, and companies manufacturing

K. R. Rao

1968-01-01

256

Proceedings of the 25th intersociety energy conversion engineering conference  

Microsoft Academic Search

This book contains the proceedings of the 25th intersociety energy conversion engineering conference. Volume 1 is organized under the following headings: space power systems requirements and issues, space power systems; space power systems 2; space nuclear power reactors space nuclear reactor technology I; space nuclear reactor technology II; reactor technology; isotopic fueled power systems I, isotopic fueled power systems II,

P. A. Nelson; W. W. Schertz; R. H. Till

1990-01-01

257

Proceedings of the 25th Intersociety Energy Conversion Engineering Conference  

Microsoft Academic Search

This book contains papers presented at a conference on energy conversion engineering. Topics covered include: USAF space power requirements, modelling of the dynamics of a low speed gas-liquid heat engine, and comparative assessment of single-axis force generation mechanisms for superconducting suspensions.

P. A. Nelson; W. W. Schertz; R. H. Till

1990-01-01

258

Einstein's special and general relativity energy conversion engineering applications  

Microsoft Academic Search

The mathematical concepts defined in Einstein's special and general relativity in 1905 and the years which followed, are routinely applied to many energy conversion engineering applications which are common today. Because of routine familiarity we have lost sight of the origin of the mathematical concepts. The aim of this paper is to review several applications and relate the mathematical concepts

Floyd A. Wyczalek

1997-01-01

259

Thermodynamic limits to the conversion of blackbody radiation by quantum systems. [with application to solar energy conversion devices  

NASA Technical Reports Server (NTRS)

Using general thermodynamic arguments, we analyze the conversion of the energy contained in the radiation from a blackbody to useful work by a quantum system. We show that the energy available for conversion is bounded above by the change in free energy in the incident and reradiated fields and that this free energy change depends upon the temperature of the receiving device. Universal efficiency curves giving the ultimate thermodynamic conversion efficiency of the quantum system are presented in terms of the blackbody temperature and the temperature and threshold energy of the quantum system. Application of these results is made to a variety of systems including biological photosynthetic, photovoltaic, and photoelectrochemical systems.

Buoncristiani, A. M.; Smith, B. T.; Byvik, C. E.

1982-01-01

260

Efficient Energy Conversion of the 14 MeV Neutrons in DT Inertial Confinement Fusion  

NASA Astrophysics Data System (ADS)

In DT fusion 80 % of the energy released goes into 14 MeV neutrons, and only the remaining 20 % into charged particles. Unlike the charged particles, the uncharged neutrons cannot be confined by a magnetic field, and for this reason cannot be used for a direct conversion into electric energy. Instead, the neutrons have to be slowed down in some medium, heating this medium to a temperature of less than 103 K, with the heat removed from this medium to drive a turbo-generator. This conversion of nuclear into electric energy has a Carnot efficiency of about 30 %. For the 80 % of the energy released into neutrons, the efficiency is therefore no more than 24 %. While this low conversion efficiency cannot be overcome in magnetic confinement concepts, it can be overcome in inertial confinement concepts, by surrounding the inertial confinement fusion target with a sufficiently thick layer of liquid hydrogen and a thin outer layer of boron, to create a hot plasma fire ball. The hydrogen layer must be chosen just thick and dense enough to be heated by the neutrons to 100,000 K. The thusly generated, fully ionized, and rapidly expanding fire ball can drive a pulsed magnetohydrodynamic generator at an almost 100 % Carnot efficiency, or possibly be used to generate hydrocarbons.

Winterberg, F.

2013-02-01

261

Solid State NMR Studies of Energy Conversion and Storage Materials  

NASA Astrophysics Data System (ADS)

NMR (Nuclear magnetic resonance) spectroscopy is utilized to study energy conversion and storage materials. Different types of NMR techniques including Magic Angle Spinning, Cross-polarization and relaxation measurement experiments were employed. Four different projects are discussed in this dissertation. First, three types of CFx battery materials were investigated. Electrochemical studies have demonstrated different electrochemical performances by one type, delivering superior performance over the other two. 13C and 19F MAS NMR techniques are employed to identify the atomic/molecular structural factors that might account for differences in electrochemical performance among different types. Next as the second project, layered polymer dielectrics were investigated by NMR. Previous studies have shown that thin film capacitors are improved by using alternate layers of two polymers with complementary properties: one with a high breakdown strength and one with high dielectric constant as opposed to monolithic layers. 13C to 1H cross-polarization techniques were used to investigate any inter-layer properties that may cause the increase in the dielectric strength. The third project was to study two types of thermoelectric materials. These samples were made of heavily doped phosphorous and boron in silicon by two different methods: ball-milled and annealed. These samples were investigated by NMR to determine the degree of disorder and obtain insight into the doping efficiency. The last ongoing project is on a lithium-ion battery system. The nature of passivating layers or the solid electrolyte interphase (SEI) formed on the electrodes surface is important because of the direct correlation between the SEI and the battery life time/durability. Multinuclear (7Li, 19F, 31P) techniques are employed to identify the composition of the SEI formation of both positive and negative electrodes.

Jankuru Hennadige, Sohan Roshel De Silva

262

Maximal spin and energy conversion efficiency in a symbiotic system of black hole, disc and jet  

NASA Astrophysics Data System (ADS)

We study a combined model of black hole-accretion disc-magnetosphere-jet symbiosis, applicable for supermassive black holes. We quantify the mass and spin evolution and analyse how the limiting value of the spin parameter and the conversion efficiency of accreted mass into radiation depend on the interplay of the electromagnetic radiation reaction, magnetosphere characteristics and truncation radius of radiation. The dominant effect comes from the closed magnetic field line region, which reduces the spin limit to values ˜0.89 (instead ˜0.99 in its absence). Therefore, observations on black hole spins could favour or disfavour the existence of the closed magnetic field line region (or its coupling to the disc). We also find that the suppression of radiation from the innermost part of the accretion disc, inferred from observations, and a collimated jet both increase the spin limit and the energy conversion efficiency.

Kovács, Zoltán; Gergely, Lászlóá.; Biermann, Peter L.

2011-09-01

263

Maximal spin and energy conversion efficiency in a symbiotic system of black hole, disk and jet  

E-print Network

We study a combined model of black hole - accretion disk - magnetosphere - jet symbiosis, applicable for supermassive black holes. We quantify the mass and spin evolution and we analyze how the limiting value of the spin parameter and the conversion efficiency of accreted mass into radiation depend on the interplay of electromagnetic radiation reaction, magnetosphere characteristics and truncation radius of radiation. The dominant effect comes from the closed magnetic field line region, which reduces the spin limit to values ~0.89 (instead ~0.99 in its absence). Therefore observations on black hole spins could favour or disfavour the existence of the closed magnetic field line region (or its coupling to the disk). We also find that the suppression of radiation from the innermost part of the accretion disk, inferred from observations, and a collimated jet both increase the spin limit and the energy conversion efficiency.

Zoltán Kovács; László Á. Gergely; Peter L. Biermann

2011-10-13

264

MHD gas turbine energy conversion for mirror fusion reactors  

Microsoft Academic Search

An MHD gas turbine energy conversion system for mirror fusion reactors is proposed. An inert-gas working fluid, which has been heated in the blanket, is superheated in a plasma thermalizer up to 2800 ? 3000 K, where the charged-particle energy from the open ends of a mirror and from neutral-beam injectors is thermalized. – Overall-efficiency calculations show that the MHD

S. Shioda; K. Maeda

1979-01-01

265

Control policies for wind-energy conversion systems  

Microsoft Academic Search

Wind energy is usually converted into electrical energy through a wind rotor driving a generator. It is well known that maximum conversion efficiency occurs when the wind rotor is loaded in such a way that its rotational speed is allowed to fluctuate in sympathy with wind-speed variations. In the paper, the wind-rotor\\/generator dynamics are investigated for a number of control

I. K. Buehring; L. L. Freris

1981-01-01

266

Saturation and energy-conversion efficiency of auroral kilometric radiation  

NASA Technical Reports Server (NTRS)

A quasi-linear theory is used to study the saturation level of the auroral kilometric radiation. The investigation is based on the assumption that the emission is due to a cyclotron maser instability as suggested by Wu and Lee and Lee et al. The thermodynamic bound on the radiation energy is also estimated separately. The energy-conversion efficiency of the radiation process is discussed. The results are consistent with observations.

Wu, C. S.; Tsai, S. T.; Xu, M. J.; Shen, J. W.

1981-01-01

267

Future of photovoltaic energy conversion in developing countries  

SciTech Connect

Recent studies reveal that photovoltaic energy conversion will be economically viable for usage in developing countries. An overview of programs designed to lower the costs of such conversion systems is presented. Government goals are reviewed, as well as application projects relative to rural usage. A summary of the state-of-the-art in both advanced research and commercially available technology is presented. It is concluded that with the range of the work being done, such systems will be viable for many rural applications within 5 years.

Hogan, S.

1980-04-01

268

SOLID STATE ENERGY CONVERSION ALLIANCE DELPHI SOFC  

SciTech Connect

The objective of Phase I under this project is to develop a 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. During Phase I, the following will be accomplished: Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with piped-in water (Demonstration System A); and Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate Catalytic Partial Oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This technical progress report covers work performed by Delphi from July through December 2002 under Department of Energy Cooperative Agreement DE-FC-02NT41246 for the 5 kW mass-market automotive (gasoline) auxiliary power unit. This report highlights technical results of the work performed under the following tasks for the automotive 5 kW system: Task 1--System Design and Integration; Task 2--Solid Oxide Fuel Cell Stack Developments; Task 3--Reformer Developments; Task 4--Development of Balance of Plant (BOP) Components; Task 5--Manufacturing Development (Privately Funded); Task 6--System Fabrication; and Task 7--System Testing.

Steven Shaffer; Sean Kelly; Subhasish Mukerjee; David Schumann; H. Skip Mieney

2003-06-09

269

SPS energy conversion and power management workshop. Final report  

SciTech Connect

In 1977 a four year study, the concept Development and Evaluation Program, was initiated by the US Department of Energy and the National Aeronautics and Space Administration. As part of this program, a series of peer reviews were carried out within the technical community to allow available information on SPS to be sifted, examined and, if need be, challenged. The SPS Energy Conversion and Power Management Workshop, held in Huntsville, Alabama, February 5 to 7, 1980, was one of these reviews. The results of studies in this particular field were presented to an audience of carefully selected scientists and engineers. This first report summarizes the results of that peer review. It is not intended to be an exhaustive treatment of the subject. Rather, it is designed to look at the SPS energy conversion and power management options in breadth, not depth, to try to foresee any troublesome and/or potentially unresolvable problems and to identify the most promising areas for future research and development. Topics include photovoltaic conversion, solar thermal conversion, and electric power distribution processing and power management. (WHK)

Not Available

1980-06-01

270

A high-efficiency energy conversion system  

SciTech Connect

A fundamentally new method for converting pressure into rotative motion is introduced. A historical background is given and an idealized non-turbine Brayton cycle engine and associated equations are described. Salient features are explained, together with suggested applications. Concerns over global warming, unacceptable levels of air pollution, and the need for more efficient utilization of nonrenewable energy resources, are issues which continue to plague us. The situation is further exacerbated by the possibility that underdeveloped countries, under pressure to expand their economies, might adopt power generating systems which could produce high levels of emissions. This scenario could easily develop if equipment, which once complied with stringent standards, failed to be adequately maintained through the absence of a reliable technical infrastructure. The Brayton cycle manometric engine has the potential for eliminating, or at least mitigating, many of the above issues. It is therefore of considerable importance to all populations, irrespective of demographic or economic considerations. This engine is inherently simple--the engine proper has only one moving part. It has no pistons, vanes, or other such conventional occlusive devices, yet it is a positive displacement machine. Sealing is achieved by what can best be described as a series of traveling U-tube manometers. Its construction does not require precision engineering nor the use of exotic materials, making it easy to maintain with the most rudimentary resources. Rotational velocity is low, and its normal life cycle is expected to extend to several decades. These advantages more than offset the machine`s large size. It is suited only to large and medium-scale stationary applications.

Belcher, A.E.

1996-12-31

271

ECE 331 Electromechanical Energy Conversion Catalog Description: Energy conversion principles for electric motors. Steady-state  

E-print Network

for electric motors. Steady-state characteristics and analysis of induction, synchronous and direct current (primary), Julia Zhang (secondary) Course Content: Magnetic circuits, magnetic materials, permanent. Introduction to drives and power electronics in control of electric machines, including switch-mode PWM

272

NSF Workshop on Emerging Opportunities of Nanoscience to Energy Conversion and Storage  

E-print Network

NSF Workshop on Emerging Opportunities of Nanoscience to Energy Conversion and Storage Download PDF: Nanoelectronics for Energy Conversion by Stuart Lindsay Section 6: BioNano Techniques for Energy Applications by T:NationalScienceFoundation(NSF)Sponsoredby:NationalScienceFoundation(NSF) #12;#12;NSF Workshop on Emerging Opportunities of Nanoscience to Energy Conversion and Storage Summary

Reif, John H.

273

High-Speed Liquid Projectiles: an Efficient Energy Conversion Tool  

NASA Astrophysics Data System (ADS)

Application of high speed liquid projectiles for enhancement of the efficiency and reduction of the emission of fuel combustion is discussed. Overall energy efficiency of combustion can be improved if combustion products generated at an extreme high rate are used as a working fluid in material processing or energy conversion operations. In the course of a performed study the products of the powder combustion were used for generation of high speed (1000-1750 m/s) liquid projectiles. The energy effectiveness of the use of these projectiles for metal forming, welding and rocks boring was demonstrated. The feasibility of development of an emission free coal combustion technology is also discussed.

Geskin, Ernest S.

2008-08-01

274

Continuous reconnection line and pressure-dependent energy conversion on the magnetopause in a global MHD model  

Microsoft Academic Search

We present results on magnetopause reconnection processes in the Gumics-4 global MHD simulation model. The reconnection line on the magnetopause is identified using a topological method, and its behavior as a function of the interplanetary magnetic field (IMF) direction is shown to be consistent with the component reconnection hypothesis. Energy conversion associated with reconnection is quantified using integrals of Poynting

T. V. Laitinen; M. Palmroth; T. I. Pulkkinen; P. Janhunen; H. E. J. Koskinen

2007-01-01

275

Energy: A continuing bibliography with indexes, February 1975. [solar energy, energy conversion  

NASA Technical Reports Server (NTRS)

Reports, articles, and other documents introduced into the NASA scientific and technical information system from July 1, 1974 through September 30, 1974 are cited. Regional, national, and international energy systems; research and development on fuels and other sources of energy; energy conversion, transport, transmission, distribution, and storage, with emphasis on the use of hydrogen and solar energy are included along with methods of locating or using new energy resources. Emphasis is placed on energy for heating, lighting, and powering aircraft, surface vehicles, or other machinery.

1975-01-01

276

Thermoelectric Energy Conversion: Future Directions and Technology Development Needs  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the process of thermoelectric energy conversion along with key technology needs and challenges. The topics include: 1) The Case for Thermoelectrics; 2) Advances in Thermoelectrics: Investment Needed; 3) Current U.S. Investment (FY07); 4) Increasing Thermoelectric Materials Conversion Efficiency Key Science Needs and Challenges; 5) Developing Advanced TE Components & Systems Key Technology Needs and Challenges; 6) Thermoelectrics; 7) 200W Class Lightweight Portable Thermoelectric Generator; 8) Hybrid Absorption Cooling/TE Power Cogeneration System; 9) Major Opportunities in Energy Industry; 10) Automobile Waste Heat Recovery; 11) Thermoelectrics at JPL; 12) Recent Advances at JPL in Thermoelectric Converter Component Technologies; 13) Thermoelectrics Background on Power Generation and Cooling Operational Modes; 14) Thermoelectric Power Generation; and 15) Thermoelectric Cooling.

Fleurial, Jean-Pierre

2007-01-01

277

Photosynthetic energy conversion in the diatom Phaeodactylum tricornutum  

Microsoft Academic Search

Isothermal microcalorimetry can be used to investigate the photosynthetic energy conversion of autotrophic organisms. In this\\u000a study, for the first time a diatom alga was used to compare the calorimetrically measured heat flux with measurements of the\\u000a photosynthetic performance by oxygen evolution and pulse-amplitude modulated fluorescence. The presented experimental setup\\u000a proved suitable to compare calorimetric data with those of conventional

Steffen Oroszi; Torsten Jakob; Christian Wilhelm; Hauke Harms; Thomas Maskow

2011-01-01

278

Magnetohydrodynamic energy conversion by using convexly divergent channel  

NASA Astrophysics Data System (ADS)

We describe a magnetohydrodynamic (MHD) electrical power generator equipped with a convexly divergent channel, as determined through shock-tunnel-based experiments. The quality of MHD power-generating plasma and the energy conversion efficiency in the convexly divergent channel are compared with those from previous linearly divergent channel. The divergence enhancement in the channel upstream is effective for suppressing an excessive increase in static pressure, whereby notably high isentropic efficiency is achieved.

Murakami, Tomoyuki; Okuno, Yoshihiro

2009-12-01

279

Monolithic interconnected modules (MIMs) for thermophotovoltaic energy conversion  

Microsoft Academic Search

Monolithic interconnected modules (MIMs) are under development for thermophotovoltaic (TPV) energy conversion applications. MIM devices are typified by series-interconnected photovoltaic cells on a common, semi-insulating substrate and generally include rear-surface infrared (IR) reflectors. The MIM architecture is being implemented in InGaAsSb materials without semi-insulating substrates through the development of alternative isolation methodologies. Motivations for developing the MIM structure include: reduced

David Wilt; Rebecca Wehrer; Marc Palmisiano; Mark Wanlass; Christopher Murray

2003-01-01

280

Fluidized-bed energy technology for biomass conversion  

Microsoft Academic Search

Fluidized-bed technology offers several unique features for use in small-scale biomass energy conversion. Results are reported in the use of a 61-cm fluidized-bed reactor for combustion and on the use of 61-, 30-, and 5-cm reactors for gasification. combustion trials using agricultural biomass feeds have identified several problem areas. Slagging and fouling can occur at bed temperatures as low as

E. J. Soltes; W. A. Lepori; T. C. Pollock

1982-01-01

281

Thermophotovoltaic energy conversion using photonic bandgap selective emitters  

DOEpatents

A method for thermophotovoltaic generation of electricity comprises heating a metallic photonic crystal to provide selective emission of radiation that is matched to the peak spectral response of a photovoltaic cell that converts the radiation to electricity. The use of a refractory metal, such as tungsten, for the photonic crystal enables high temperature operation for high radiant flux and high dielectric contrast for a full 3D photonic bandgap, preferable for efficient thermophotovoltaic energy conversion.

Gee, James M. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM); Fleming, James G. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

2003-06-24

282

Advanced materials and coatings for energy conversion systems  

Microsoft Academic Search

Following an historical review of the development of high-temperature alloys for energy conversion systems including turbine engines, some of the current advances in single crystal materials. intermetallics, metal-matrix composites, and ceramic-matrix composites are discussed. Particular attention is directed at creep phenomena, fatigue properties, and oxidation resistance. Included within the discussions is the current status of carbon\\/carbon composites as potential high-temperature

George R. St. Pierre

1997-01-01

283

Power Control and Optimization of Photovoltaic and Wind Energy Conversion Systems /  

E-print Network

Energy Conversion Systems by Azad Ghaffari Doctor of Philosophy in EngineeringEnergy Conversion Systems A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Engineering

Ghaffari, Azad

2013-01-01

284

Cluster Observations of Energy Conversion Regions in the Plasma Sheet  

NASA Astrophysics Data System (ADS)

Cluster allows for the first time a systematic examination of energy conversion, by the evaluation of the power density, E · J, with E the electric field and J the current density. Following a careful inspection of the Cluster plasma sheet data from the summer and fall of 2001, we selected 43 energy conversion regions (ECRs), out of which 26 concentrated load regions (CLRs, E · J > 0) and 17 concentrated generator regions (CGRs, E · J < 0). As expected in the tail, at about 19 RE geocentric distance, the energy conversion is more intense for CLRs, on average some 25 pW/m3, compared to some 5 pW/m3 for CGRs. The CLRs are located closer to the neutral sheet and dominated by E and J in the GSE y direction, unlike the CGRs, that prefer locations towards the plasma sheet boundary layer, where the deviations of E and J from the GSE y direction can be significant. The ECRs are often associated with high speed bulk flows, on average faster and hotter for CLRs. The CLRs appear to be associated also with density drop and sometimes with temperature anisotropy, T? > T?, features which are observed less frequently for CGRs.

Marghitu, O.; Hamrin, M.; Klecker, B.; Rönnmark, K.; Buchert, S.; Kistler, L. M.; André, M.; Rème, H.

285

Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA  

SciTech Connect

The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100?ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6–1.0 ? in about 10–20?ns.

Liangping, Wang; Mo, Li; Juanjuan, Han; Ning, Guo [Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Key State Laboratory of Simulation and Effect for Intense Pulse Radiation, Xi'an 710024 (China); Jian, Wu [Xi'an Jiaotong University, Xi'an 710049 (China); Aici, Qiu [Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Xi'an Jiaotong University, Xi'an 710049 (China)

2014-06-15

286

Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA  

NASA Astrophysics Data System (ADS)

The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100 ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6-1.0 ? in about 10-20 ns.

Liangping, Wang; Mo, Li; Juanjuan, Han; Jian, Wu; Ning, Guo; Aici, Qiu

2014-06-01

287

Nanostructured materials for advanced energy conversion and storage devices  

NASA Astrophysics Data System (ADS)

New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. This review describes some recent developments in the discovery of nanoelectrolytes and nanoelectrodes for lithium batteries, fuel cells and supercapacitors. The advantages and disadvantages of the nanoscale in materials design for such devices are highlighted.

Aricò, Antonino Salvatore; Bruce, Peter; Scrosati, Bruno; Tarascon, Jean-Marie; van Schalkwijk, Walter

2005-05-01

288

Nanostructured materials for advanced energy conversion and storage devices.  

PubMed

New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. This review describes some recent developments in the discovery of nanoelectrolytes and nanoelectrodes for lithium batteries, fuel cells and supercapacitors. The advantages and disadvantages of the nanoscale in materials design for such devices are highlighted. PMID:15867920

Aricò, Antonino Salvatore; Bruce, Peter; Scrosati, Bruno; Tarascon, Jean-Marie; van Schalkwijk, Walter

2005-05-01

289

Advanced study of ICF-energy direct conversion for laser fusion rocket with quasi-dipole field in the laser-plasma experiments and PIC-simulations  

Microsoft Academic Search

We had studied by the methods of numerical and laboratory simulations an important problem of direct inductive conversion of the ICF-plasma' energy into electric one, under conditions of promising space propulsions with magnetic nozzle. For such kind of Laser Fusion Rocket, like a VISTA, with the strong and dipole-like magnetic field, a minimal 5%-level of conversion efficiency is required to

Y. P. Zakharov; K. V. Vchivkov; H. Nakashima; E. L. Boyarintsev; A. V. Melekhov; V. G. Posukh; I. F. Shaikhislamov; Y. Kajimura

2008-01-01

290

A novel method of energy conversion and storage in Photoelectric Micropower Supply  

Microsoft Academic Search

In wireless sensor nodes integrated with photoelectric micro-power supply, the efficiency of energy conversion and storage of photoelectric micro-power supply (PMPS) determines their lifetime and adaptability to the environment. Therefore, it is important to improve the efficiency of the energy conversion and storage in the PMPS. However, traditional methods to improve the efficiency of the energy conversion and storage of

He Yong-tai; Wang Lei

2009-01-01

291

Research on the optimal control method of wind and electric energy conversion  

Microsoft Academic Search

The author first analyses the energy conversion of wind power generation and the main factor of influencing output power from the perspective of energy conversion and equilibrium. With the method of coordinate transformation, the output power is decomposed into active component and reactive component. Then based on the ideas of optimal control of wind and electric energy conversion, the relation

Wei Wei; Peng Xue

2010-01-01

292

Dynamical mechanism for the conversion of energy at a molecular scale Naoko Nakagawa  

E-print Network

Dynamical mechanism for the conversion of energy at a molecular scale Naoko Nakagawa Department mechanism of a molecular machine for energy conversion, by considering a simple model describing is thermal ratchet 4­7 , which gives one plausible mechanism for the conversion of energy to mechanical work

Kaneko, Kunihiko

293

Energy Conversion Unit with Optimized Waveform Generation Sally Sajadian and Euzeli C. dos Santos Jr.  

E-print Network

Energy Conversion Unit with Optimized Waveform Generation Sally Sajadian and Euzeli C. dos Santos to increase the efficiency of the devices dealing with energy conversion. The power supplies devices able and interleaved converters. This paper proposes an energy conversion unit constituted by a single-phase DC

Zhou, Yaoqi

294

Energy conversion at the Earth's magnetopause using single and multispacecraft methods  

E-print Network

Energy conversion at the Earth's magnetopause using single and multispacecraft methods C. R a small statistical data set, where we investigate energy conversion at the magnetopause using Cluster density and magnetopause orientation are needed to infer the energy conversion at the magnetopause

Bergen, Universitetet i

295

Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems  

E-print Network

Sliding Mode Power Control of Variable Speed Wind Energy Conversion Systems B. Beltran, T. Ahmed power generation in variable speed wind energy conversion systems (VS-WECS). These systems have two variations. Index Terms--Wind energy conversion system, power generation control, sliding mode control

Boyer, Edmond

296

Energy conversion by autonomous regulation of chaos: Dynamical mechanism of loose coupling  

E-print Network

Energy conversion by autonomous regulation of chaos: Dynamical mechanism of loose coupling Naoko by temporal three-body motion, is relevant to the energy conversion. © 2003 American Institute of Physics. DOI, the proposed mechanism is expected to be rather general and is applicable to other energy conversion problems

Kaneko, Kunihiko

297

Assistant, Associate or Full Professor (Mid-Career)(10-657) Energy Conversion Position in MAE  

E-print Network

Assistant, Associate or Full Professor (Mid-Career)(10-657) Energy Conversion Position in MAE of Energy Conversion. We are particularly interested in novel computational, theoretical, and experimental, and biofuels. Excellent candidates in other areas of energy conversion will also be given full consideration

Gleeson, Joseph G.

298

The State of the Art of Generators for Wind Energy Conversion Systems  

E-print Network

The State of the Art of Generators for Wind Energy Conversion Systems Yassine Amirat, Mohamed Benbouzid, Bachir Bensaker and René Wamkeue Abstract--Wind Energy Conversion Systems (WECS) have become. I. INTRODUCTION Wind energy conversion is the fastest-growing source of new electric generation

Boyer, Edmond

299

The State of the Art of Generators for Wind Energy Conversion Systems  

E-print Network

243 1 The State of the Art of Generators for Wind Energy Conversion Systems Y. Amirat, M. E. H. Benbouzid, B. Bensaker, R. Wamkeue and H. Mangel Abstract--Wind Energy Conversion Systems (WECS) have become. I. INTRODUCTION IND energy conversion is the fastest-growing source of new electric generation

Paris-Sud XI, Université de

300

A Framework for Reliability and Performance Assessment of Wind Energy Conversion Systems  

E-print Network

1 A Framework for Reliability and Performance Assessment of Wind Energy Conversion Systems proposes a framework for reliability and dynamic performance assessment of wind energy conversion systems--Reliability, Dynamic Performance, Wind Power, Wind Energy Conversion System (WECS), Doubly-Fed Induction Generator

Liberzon, Daniel

301

Simulation results of an efficient and innovative sun engine for solar to electrical energy conversion  

Microsoft Academic Search

According to future trends of renewable energy conversion conducted by the severe reduction of irreversibilities required since the design phase, a philosophy of design is presented: efficient renewable energy conversion systems focusing the attention on frictionless and vacuum environments. Then an innovative and efficient sun engine, MAG-solar-1 system, is introduced for conversion of solar energy to the high quality electrical

Eduardo Velasco Orosco

2000-01-01

302

The 20 year evolution of an energy conversion course at the United States Military Academy  

Microsoft Academic Search

Over the past several years, an energy conversion course offered by the Mechanical Engineering Program at the United States Military Academy in West Point, New York, has evolved into a cohesive series of lessons addressing three general topical areas: advanced thermodynamics, advanced mechanical system analysis, and direct energy conversion systems. Mechanical engineering majors enroll in Energy Conversion Systems (ME 472)

Margaret Bailey; A. Özer Arnas; Robert Potter; Jerry W. Samples

2004-01-01

303

A New Realistic Characteristics of Real Energy Conversion Process: A Contribution of Finite Size Thermodynamics  

Microsoft Academic Search

The perfection of the energy conversion process is currently gauged through a kind of quality indicator that compares the real performance of the process to that of the ideal reversible Carnot process. The criteria resulting from this commonly used approach give a false idea as to the real quality of the energy conversion process. Indeed, the real energy conversion process

Driss Stitou; Bernard Spinner

2005-01-01

304

Compact magnetic energy storage module  

DOEpatents

A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module.

Prueitt, Melvin L. (Los Alamos, NM)

1994-01-01

305

Compact magnetic energy storage module  

DOEpatents

A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module. 4 figures.

Prueitt, M.L.

1994-12-20

306

Investigation of direct solar-to-microwave energy conversion techniques  

NASA Technical Reports Server (NTRS)

Identification of alternative methods of producing microwave energy from solar radiation for purposes of directing power to the Earth from space is investigated. Specifically, methods of conversion of optical radiation into microwave radiation by the most direct means are investigated. Approaches based on demonstrated device functioning and basic phenomenologies are developed. There is no system concept developed, that is competitive with current baseline concepts. The most direct methods of conversion appear to require an initial step of production of coherent laser radiation. Other methods generally require production of electron streams for use in solid-state or cavity-oscillator systems. Further development is suggested to be worthwhile for suggested devices and on concepts utilizing a free-electron stream for the intraspace station power transport mechanism.

Chatterton, N. E.; Mookherji, T. K.; Wunsch, P. K.

1978-01-01

307

Energy conversion issues for airborne directed energy weapons  

Microsoft Academic Search

The ability of an airborne directed energy weapon (DEW) to effectively strike a target depends strongly on the ability to develop, deliver, and manage the required energy for the onboard DEW source. The energy flow within various generic airborne DEW systems is examined from power generation to waste heat management. Each airborne DEW system is analyzed by considering the energy

Steven F. Adams; John G. Nairus

2002-01-01

308

IEEE TRANSACTIONS ON ENERGY CONVERSION, 2006 1 Distributed Control Agents Approach to Energy  

E-print Network

IEEE TRANSACTIONS ON ENERGY CONVERSION, 2006 1 Distributed Control Agents Approach to Energy a new scheme for an energy management system in the form of distributed control agents. The control architecture to function as energy management system is presented. Index Terms-- integrated electric power

Lai, Hong-jian

309

ER100/PPC184/ER200/PPC284, Fall 2014 Energy Units & Conversions, Global Energy Use  

E-print Network

1 ER100/PPC184/ER200/PPC284, Fall 2014 Energy Units & Conversions, Global Energy Use Problem Set #1 Total Points: 100 for ER110/PPC184; 120 for ER200/PPC284 Energy Units The purpose of these problems is to begin to get comfortable with the wide array of energy units used, and to gain experience in both doing

Kammen, Daniel M.

310

Renewable energy from the sea - organic Rankine Cycle using ocean thermal energy conversion  

Microsoft Academic Search

Rankine cycles using refrigerant- and benzene-series fluids as working fluids in converting low-grade energy from renewable energy resources such as solar energy and ocean thermal energy were investigated in this study. The main purpose is to verify the feasibility of utilizing ocean energy (i.e., ocean thermal energy conversion, OTEC) which can also be combined with solar energy in an organic

S. K. Wang; T. C. Hung

2010-01-01

311

Energy transfer up-conversion in Tm3+ -doped silica fibre  

E-print Network

1 Energy transfer up-conversion in Tm3+ - doped silica fibre D. A. Simpson, G. W. Baxter and S. F responsible for the up-conversion: excited state absorption and energy transfer up-conversion. The decay equations, the energy transfer up- conversion process (3 F4,3 F43 H4,3 H6) is established at Tm2O3

Paris-Sud XI, Université de

312

Recycling of wasted energy : thermal to electrical energy conversion.  

E-print Network

??Harvesting useful electric energy from ambient thermal gradients and/or temperature fluctuations is immensely important. For many years, a number of direct and indirect thermal-to-electrical energy… (more)

Lim, Hyuck

2011-01-01

313

Assessment of Methods to Manipulate Thermal Emission and Evaluate the Quality of Thermal Radiation for Direct Energy Conversion.  

E-print Network

??ABSTRACT Control of spectral thermal emission from surfaces may be desirable in some energy related applications, such as nano-scale antenna energy conversion and thermophotovoltaic conversion.… (more)

Wijewardane, Samantha

2012-01-01

314

Explorations of Novel Energy Conversion and Storage Systems  

NASA Astrophysics Data System (ADS)

At present, the majority of the world's energy demand is met by the consumption of exhaustible fuel supplies. Consequently, it is urgent to research and develop viable alternatives. In this dissertation, I present research that addresses fundamental questions concerning how water interacts with surfaces and solutes, with the goal of identifying novel systems for energy production and storage. Electrokinetic currents are created when moving fluid entrains charge from the diffuse portion of an electric double layer and carries that charge downstream. The potential difference that develops on either end of the channel is known as the streaming potential. Chapter 2 of this dissertation focuses on electrokinetic energy production and conversion efficiency of liquid microjets. Section 1 of Chapter 2 presents proof-of-principle research demonstrating that molecular hydrogen is generated from electrokinetic currents in liquid water microjets. Hydrogen is generated when hydrated protons are preferentially carried downstream and recombine with electrons at a grounded target electrode. Both the current and hydrogen production scale nearly quadratically with flow rate, as predicted by equations derived from simple double layer theory and fluid mechanics. The efficiency is currently very low (ca 10-6) and is limited by the low electrokinetic current (˜nA). Designs to improve this efficiency are considered. Rather than chemical conversion efficiency, Section 2 of Chapter 2 investigates the electrical conversion efficiency of liquid water microjets. Typical electrokinetic energy conversion schemes measure current or voltage via electrodes in the fluid reservoirs on either side of a channel. With this design, the streaming potential drives a current against the flow of the fluid and, consequently, limits the conversion efficiency. In contrast, liquid microjets break up into droplets before reaching the downstream electrode and this eliminates the possibility for back conduction. As a result, liquid microjets yield conversion efficiencies exceeding 10%, much larger than channel-dependent measurements (˜3%). It is the large potentials obtainable with electrokinetic currents (tens of kilovolts) that drive up the electrical conversion efficiency. Unfortunately, low currents with high voltages are inconvenient for application. Section 3 of Chapter 2 describes efforts to utilize the high voltage of electrokinetic currents by coupling light into the process. More specifically, the streaming potential is used to modify the space charge layer in a semiconductor and, consequently, the light harvesting characteristics of that semiconductor. To this end, microchannel jets fabricated out of glass and silicon were built to allow light to impinge on the current generating surface. Although plagued with inconsistent results, streaming currents were found to increase upon illumination and some channels even gave measurable responses to ambient room lights. Chapter 3 of this dissertation addresses the details of hydration of boron-oxides and sodium borohydride as studied by near edge x-ray absorption fine structure spectroscopy (NEXAFS) and associated theory. Boron-oxides and molecular hydrogen are products of borohydride hydrolysis which has been intensely studied for hydrogen storage purposes. In spite of their hydroxide moieties, boron-oxides turn out to not be strongly hydrated by water. The experimental spectra, as well as attending calculations, show no evidence for electronic coupling that would indicate strong hydrogen bonding between the boron-oxides and water. On the other hand, the NEXAFS spectrum of sodium borohydride is significantly altered by water. The experiment and calculations show strong evidence for short dihydrogen bonds between water hydrogens and borohydride hydrogens. Molecular dynamics simulations indicate that borohydride is hydrated at the tetrahedral corners and edge.

Duffin, Andrew Mark

315

Surface conversion techniques for low energy neutral atom imagers  

NASA Technical Reports Server (NTRS)

This investigation has focused on development of key technology elements for low energy neutral atom imaging. More specifically, we have investigated the conversion of low energy neutral atoms to negatively charged ions upon reflection from specially prepared surfaces. This 'surface conversion' technique appears to offer a unique capability of detecting, and thus imaging, neutral atoms at energies of 0.01 - 1 keV with high enough efficiencies to make practical its application to low energy neutral atom imaging in space. Such imaging offers the opportunity to obtain the first instantaneous global maps of macroscopic plasma features and their temporal variation. Through previous in situ plasma measurements, we have a statistical picture of large scale morphology and local measurements of dynamic processes. However, with in situ techniques it is impossible to characterize or understand many of the global plasma transport and energization processes. A series of global plasma images would greatly advance our understanding of these processes and would provide the context for interpreting previous and future in situ measurements. Fast neutral atoms, created from ions that are neutralized in collisions with exospheric neutrals, offer the means for remotely imaging plasma populations. Energy and mass analysis of these neutrals provides critical information about the source plasma distribution. The flux of neutral atoms available for imaging depends upon a convolution of the ambient plasma distribution with the charge exchange cross section for the background neutral population. Some of the highest signals are at relatively low energies (well below 1 keV). This energy range also includes some of the most important plasma populations to be imaged, for example the base of the cleft ion fountain.

Quinn, J. M.

1995-01-01

316

Artificial photosynthesis: biomimetic approaches to solar energy conversion and storage.  

PubMed

Using sun as the energy source, natural photosynthesis carries out a number of useful reactions such as oxidation of water to molecular oxygen and fixation of CO(2) in the form of sugars. These are achieved through a series of light-induced multi-electron-transfer reactions involving chlorophylls in a special arrangement and several other species including specific enzymes. Artificial photosynthesis attempts to reconstruct these key processes in simpler model systems such that solar energy and abundant natural resources can be used to generate high energy fuels and restrict the amount of CO(2) in the atmosphere. Details of few model catalytic systems that lead to clean oxidation of water to H(2) and O(2), photoelectrochemical solar cells for the direct conversion of sunlight to electricity, solar cells for total decomposition of water and catalytic systems for fixation of CO(2) to fuels such as methanol and methane are reviewed here. PMID:20439158

Kalyanasundaram, K; Graetzel, M

2010-06-01

317

Quantum coherence in photosynthesis for efficient solar-energy conversion  

NASA Astrophysics Data System (ADS)

The crucial step in the conversion of solar to chemical energy in photosynthesis takes place in the reaction centre, where the absorbed excitation energy is converted into a stable charge-separated state by ultrafast electron transfer events. However, the fundamental mechanism responsible for the near-unity quantum efficiency of this process is unknown. Here we elucidate the role of coherence in determining the efficiency of charge separation in the plant photosystem II reaction centre by comprehensively combining experiment (two-dimensional electronic spectroscopy) and theory (Redfield theory). We reveal the presence of electronic coherence between excitons as well as between exciton and charge-transfer states that we argue to be maintained by vibrational modes. Furthermore, we present evidence for the strong correlation between the degree of electronic coherence and efficient and ultrafast charge separation. We propose that this coherent mechanism will inspire the development of new energy technologies.

Romero, Elisabet; Augulis, Ramunas; Novoderezhkin, Vladimir I.; Ferretti, Marco; Thieme, Jos; Zigmantas, Donatas; van Grondelle, Rienk

2014-09-01

318

Science in Focus: Transfer and Conversion of Energy  

NSDL National Science Digital Library

What happens when energy is converted from one form to another? This free one-hour professional development video for K-8 teachers explores the topic through examples of conversion between potential and kinetic energy. The video is designed so that teachers come away with an understanding that will help them engage students in their own explorations. Editor's Note: This resources offer excellent support for teachers to update content knowledge in energy conservation, important to meet revised science curriculum standards being adopted by many states. This collection is part of a larger set of video workshops published and maintained by the Annenberg Foundation. Other workshop topics in physical science include Forces and Motion, Chemistry, and Light.

2011-03-14

319

Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion  

NASA Technical Reports Server (NTRS)

Tailoring the solar absorptivity (alpha(sub s)) and thermal emissivity (epsilon(sub T)) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for solar absorbance/thermal emittance control. However, conventional metal oxides and dielectric/metal/dielectric multi-coatings have limited utility due to residual shear stresses resulting from the different coefficient of thermal expansion of the layered materials. This research presents an alternate approach based on nanoparticle-filled polymers to afford mechanically durable solar-absorptive and thermally-emissive polymer nanocomposites. The alpha(sub s) and epsilon(sub T) were measured with various nano inclusions, such as carbon nanophase particles (CNPs), at different concentrations. Research has shown that adding only 5 wt% CNPs increased the alpha(sub s) and epsilon(sub T) by a factor of about 47 and 2, respectively, compared to the pristine polymer. The effect of solar irradiation control of the nanocomposite on solar energy conversion was studied. The solar irradiation control coatings increased the power generation of solar thermoelectric cells by more than 380% compared to that of a control power cell without solar irradiation control coatings.

Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.; Lowther, S. E.; Lillehei, P. T.; Bryant, R. G.

2012-01-01

320

Heat transfer research for ocean thermal energy conversion  

NASA Astrophysics Data System (ADS)

In this lecture an overview of the heat- and mass-transfer phenomena of importance in ocean thermal energy conversion (OTEC) is presented with particular emphasis on open-cycle OTEC systems. Also included is a short historical review of OTEC developments in the past century and a comparison of open- and closed-cycle thermodynamics. Finally, results of system analyses, showing the effect of plant size on cost and the near-term potential of using OTEC for combined power production and desalination systems are briefly discussed.

Kreith, F.; Bharathan, D.

1987-03-01

321

Method and apparatus for testing electrochemical energy conversion devices  

NASA Technical Reports Server (NTRS)

A system for testing electrochemical energy conversion and storage devices includes means for sensing the current from the storage device and varying the load across the storage device in response to the current sensed. The system is equally adaptable to batteries and fuel cells. Means is also provided to sense system parameters from a plurality of locations within the system. Certain parameters are then stored in digital form for archive purposes and certain other parameters are used to develop control signals in a host processor.

Cisar, Alan J. (Inventor); Murphy, Oliver J. (Inventor)

1996-01-01

322

Low cost composite materials for wind energy conversion systems  

NASA Technical Reports Server (NTRS)

A winding process utilizing a low-cost E-glass fabric called transverse-filament tape for low-cost production of wind turbine generators (WTG) is described. The process can be carried out continuously at high speed to produce large one-piece parts with tapered wall thicknesses on a tapered mandrel. It is being used to manufacture blades for the NASA/DOE 200-ft-diameter MOD-1 WTG and Rockwell/DOE 40-kW small wind energy conversion system (SWECS).

Weingart, O.

1980-01-01

323

Advanced solar energy conversion. [solar pumped gas lasers  

NASA Technical Reports Server (NTRS)

An atomic iodine laser, a candidate for the direct solar pumped lasers, was successfully excited with a 4 kW beam from a xenon arc solar simulator, thus proving the feasibility of the concept. The experimental set up and the laser output as functions of operating conditions are presented. The preliminary results of the iodine laser amplifier pumped with the HCP array to which a Q switch for giant pulse production was coupled are included. Two invention disclosures - a laser driven magnetohydrodynamic generator for conversion of laser energy to electricity and solar pumped gas lasers - are also included.

Lee, J. H.

1981-01-01

324

Photovoltaic and thermal energy conversion for solar powered satellites  

NASA Technical Reports Server (NTRS)

A summary is provided concerning the most important aspects of present investigations related to a use of solar power satellites (SPS) as a future source of terrestrial energy. General SPS characteristics are briefly considered, early work is reviewed, and a description of current investigations is presented. System options presently under study include a photovoltaic array, a thermionic system, and a closed Brayton cycle. Attention is given to system reference options, basic building blocks, questions of system analysis and engineering, photovoltaic conversion, and the utility interface. It is concluded that an SPS may be cost effective compared to terrestrial systems by 1995.

Von Tiesenhausen, G. F.

1976-01-01

325

Transmission and conversion of magnetoacoustic waves on the magnetic canopy in a quiet Sun region  

NASA Astrophysics Data System (ADS)

Context. We present evidence for the conversion and transmission of wave modes on the magnetic flux tubes that constitute mottles and form the magnetic canopy in a quiet Sun region. Aims: Our aim is to highlight the details and the key parameters of the mechanism that produces power halos and magnetic shadows around the magnetic network observed in H?. Methods: We use our previous calculations of the magnetic field vector and the height of the magnetic canopy, and based on simple assumptions, we determine the turning height, i.e., the height at which the fast magnetoacoustic waves reflect at the chromosphere. We compare the variation of 3, 5, and 7 min power in the magnetic shadow and the power halo with the results of a two-dimensional model on mode conversion and transmission. The key parameter of the model is the attack angle, which is related to the inclination of the magnetic field vector at the canopy height. Our analysis takes also into account that 1) there are projection effects on the propagation of waves; 2) the magnetic canopy and the turning height are curved layers; 3) waves with periods longer than 3 min only reach the chromosphere in the presence of inclined magnetic fields (ramp effect); 4) mottles in H? are canopy structures; and 5) the wings of H? contain mixed signal from low- and high-? plasma. Results: The dependence of the measured power on the attack angle follows the anticipated by the two-dimensional model very well. Long-period slow waves are channeled to the upper chromospheric layers following the magnetic field lines of mottles, while short-period fast waves penetrate the magnetic canopy and are reflected back higher, at the turning height. Conclusions: Although both magnetoacoustic modes contribute to velocity signals, making the interpretation of observations a challenging task, we conclude that conversion and transmission of the acoustic waves into fast and slow magnetoacoustic waves are responsible for forming power halos and magnetic shadows in the quiet Sun region.

Kontogiannis, I.; Tsiropoula, G.; Tziotziou, K.

2014-07-01

326

Direct Solar Energy Conversion at Sea \\/DSECAS\\/ - Characteristics of a baseline concept  

Microsoft Academic Search

The subject of the project is a direct solar energy conversion system sited in an equatorial ocean location. It is noted that this combination of a direct solar energy conversion system in this setting represents a heretofore unstudied family of systems. The possibility of using a number of alternative direct conversion methods such as photovoltaic, thermal heat engines, photochemical systems,

W. J. D. Escher; R. W. Foster; T. N. Veziroglu

1978-01-01

327

Investigation on energy conversion technology using biochemical reaction elements, 2  

NASA Astrophysics Data System (ADS)

For measures taken for resource/energy and environmental issues, a study is made on utilization of microbial biochemical reaction. As a reaction system using chemical energy, cited is production of petroleum substitution substances and food/feed by CO2 fixation using hydrogen energy and hydrogen bacteria. As to photo energy utilization, regarded as promising are CO2 fixation using photo energy and microalgae, and production of hydrogen and useful carbon compound using photosynthetic organisms. As living organism/electric energy interconversion, cited is the culture of chemoautotrophic bacteria which fix CO2 using electric energy. For enhancing its conversion efficiency, it is important to develop a technology of gene manipulation of the bacteria and a system to use functional biochemical elements adaptable to the electrode reaction. With regard to utilization of the microorganism metabolic function, the paper presents emission of soluble nitrogen in the hydrosphere into the atmosphere using denitrifying bacteria, removal of phosphorus, reduction in environmental pollution caused by heavy metal dilute solutions, and recovery as resources, etc.

1994-03-01

328

Energy and data conversion circuits for low power sensory systems  

NASA Astrophysics Data System (ADS)

This dissertation focuses on the problem of increasing the lifetime of wireless sensors. This problem is addressed from two different angles: energy harvesting and data compression. Energy harvesting enables a sensor to extract energy from its environment and use it to power itself or recharge its batteries. Data compression, on the other hand, allows a sensor to save energy by reducing the radio transmission bandwidth. This dissertation proposes a fractal-based photodiode fabricated on standard CMOS process as an energy harvesting device with increased efficiency. Experiments show that, the fractal based photodiodes are 6% more efficient compared to the conventional square shaped photodiode. The fractal shape photodiode has more perimeter-to-area ratio which increases the lateral response, improving its efficiency. With increased efficiency, more current is generated but the open-circuit voltage still remains low (0.3V--0.45V depending on illumination condition). These voltages have to be boosted up to higher values if they are going to be used to power up any sensory circuit or recharge a battery. We propose a switched-inductor DC-DC converter to boost the low voltage of the photodiodes to higher voltages. The proposed circuit uses two on-chip switches and two off-chip Components: an inductor and a capacitor. Experiments show a voltage up to 2.81V can be generated from a single photodiode of 1mm2 area. The voltage booster circuit achieved a conversion efficiency of 59%. Data compression was also explored in an effort to reduce energy consumption during radio transmission. An analog-to-digital converter (ADC), which can jointly perform the tasks of digital conversion and entropy encoding, has also been proposed in this dissertation. The joint data conversion/compression help savings in area and power resources, making it suitable for on-sensor compression. The proposed converter combines a cyclic converter architecture and Golomb-Rice entropy encoder. The converter hardware design is based on current-mode circuits and it was fabricated on a 0.5 mum CMOS process and tested. Experiment results show a lossless compression ratio of 1.52 and a near-lossless compression of 5.2 can be achieved for 32 x 32 pixel image.

Ghosh, Suvradip

329

PRELIMINARY ENVIRONMENTAL ASSESSMENT OF ENERGY CONVERSION PROCESSES FOR AGRICULTURAL AND FOREST PRODUCT RESIDUES. VOLUME 1  

EPA Science Inventory

A preliminary assessment was made of the environmental impacts of several types of conversion processes for producing energy or fuels from agricultural and forestry residues. Fifteen examples were selected to represent various combinations of agricultural residues and conversion ...

330

Organic electronics on fibers for energy conversion applications  

NASA Astrophysics Data System (ADS)

Currently, there is great demand for pollution-free and renewable sources of electricity. Solar cells are particularly attractive from the standpoint of sunlight abundance. However, truly widespread adoption of solar cells is impeded by the high cost and poor scalability of existing technologies. For example, while 53,000 mi2 of 10% efficient solar cell modules would be required to supply the current U.S. energy demand, only about 50 mi2 have been installed worldwide. Organic semiconductors potentially offer a route to realizing low-cost solar cell modules, but currently suffer from low conversion efficiency. For organic-based solar cells to become commercially viable, further research is required to improve device performance, develop scalable manufacturing methods, and reduce installation costs via, for example, novel device form factors. This thesis makes several contributions to the field of organic solar cells, including the replacement of costly and brittle indium tin oxide (ITO) electrodes by inexpensive and malleable, thin metal films, and the application of external dielectric coatings to improve power conversion efficiency. Furthermore, we show that devices with non-planar geometries (e.g. organic solar cells deposited onto long fibers) can have higher efficiencies than conventional planar devices. Building on these results, we demonstrate novel fiber-based organic light emitting devices (OLEDs) that offer substantially improved color quality and manufacturability as a next-generation solid-state lighting technology. An intriguing possibility afforded by the fiber-based device architectures is the ability to integrate energy conversion and lighting functionalities with textiles, a mature, commodity-scale technology.

O'Connor, Brendan T.

331

Nitride metal - semiconductor superlattices for solid state thermionic energy conversion  

NASA Astrophysics Data System (ADS)

With the current energy crisis, efficiency of thermal systems is becoming ever more important. Furthermore, as the cost of energy goes up, methods to increase efficiencies of these systems become more and more cost-effective. Waste heat from engines and power plants is a readily available source of energy that, for the most part, is not being used. Using this waste heat therefore represents the easiest method for energy recovery and generation and can result in a higher overall system efficiency. The research is focused on the direct conversion of waste heat (and in some niche applications, non-waste heat) into electricity. The method for conversion, however, differs from that of standard thermoelectric generators. Thermoelectrics tend to be homogenous materials, typically semiconductors. In contrast, the non-homogenous solid state thermionic emission device uses a layered structure of metals and semiconductors with nanometer-scale layer thicknesses. By using this structure, thermal conductivity is greatly reduced as compared to the constituent materials by means of interface scattering. In addition, if ballistic transport across the semiconductor layer can be realized, the energy in the electrons is preserved, resulting in an increased Seebeck Coecient. By these methods, the figure of merit of our devices (ZT) has been shown in theory to be much higher than currently reported devices at the temperature of interest (900 K). To this end, superlattices of ZrN/ScN and HfN/ScN have been grown via reactive D.C. magnetron sputtering. Characterization of the grown lms has been carried out using X-ray diffraction, SEM and TEM. In addition, the initial development of testing structures has been carried out. The creation of these structures using photolithography as well as wet and dry etching techniques is in the preliminary stages.

Wortman, Robert David

332

Proceedings of the Chornobyl phytoremediation and biomass energy conversion workshop  

SciTech Connect

Many concepts, systems, technical approaches, technologies, ideas, agreements, and disagreements were vigorously discussed during the course of the 2-day workshop. The workshop was successful in generating intensive discussions on the merits of the proposed concept that includes removal of radionuclides by plants and trees (phytoremediation) to clean up soil in the Chornobyl Exclusion Zone (CEZ), use of the resultant biomass (plants and trees) to generate electrical power, and incorporation of ash in concrete casks to be used as storage containers in a licensed repository for low-level waste. Twelve years after the Chornobyl Nuclear Power Plant (ChNPP) Unit 4 accident, which occurred on April 26, 1986, the primary 4radioactive contamination of concern is from radioactive cesium ({sup 137}Cs) and strontium ({sup 90}Sr). The {sup 137}Cs and {sup 90}Sr were widely distributed throughout the CEZ. The attendees from Ukraine, Russia, Belarus, Denmark and the US provided information, discussed and debated the following issues considerably: distribution and characteristics of radionuclides in CEZ; efficacy of using trees and plants to extract radioactive cesium (Cs) and strontium (Sr) from contaminated soil; selection of energy conversion systems and technologies; necessary infrastructure for biomass harvesting, handling, transportation, and energy conversion; radioactive ash and emission management; occupational health and safety concerns for the personnel involved in this work; and economics. The attendees concluded that the overall concept has technical and possibly economic merits. However, many issues (technical, economic, risk) remain to be resolved before a viable commercial-scale implementation could take place.

Hartley, J. [Pacific Northwest National Lab., Richland, WA (United States)] [Pacific Northwest National Lab., Richland, WA (United States); Tokarevsky, V. [State Co. for Treatment and Disposal of Mixed Hazardous Waste (Ukraine)] [State Co. for Treatment and Disposal of Mixed Hazardous Waste (Ukraine)

1998-06-01

333

High Temperature Fusion Reactor Cooling Using Brayton Cycle Based Partial Energy Conversion  

NASA Technical Reports Server (NTRS)

For some future space power systems using high temperature nuclear heat sources most of the output energy will be used in other than electrical form, and only a fraction of the total thermal energy generated will need to be converted to electrical work. The paper describes the conceptual design of such a partial energy conversion system, consisting of a high temperature fusion reactor operating in series with a high temperature radiator and in parallel with dual closed cycle gas turbine (CCGT) power systems, also referred to as closed Brayton cycle (CBC) systems, which are supplied with a fraction of the reactor thermal energy for conversion to electric power. Most of the fusion reactor's output is in the form of charged plasma which is expanded through a magnetic nozzle of the interplanetary propulsion system. Reactor heat energy is ducted to the high temperature series radiator utilizing the electric power generated to drive a helium gas circulation fan. In addition to discussing the thermodynamic aspects of the system design the authors include a brief overview of the gas turbine and fan rotor-dynamics and proposed bearing support technology along with performance characteristics of the three phase AC electric power generator and fan drive motor.

Juhasz, Albert J.; Sawicki, Jerzy T.

2003-01-01

334

Physlets Tour 5: Conversion from Kinetic Energy to Thermal Energy  

NSDL National Science Digital Library

A heavy ball with an initial kinetic energy of 4000 J is trapped inside a box with rigid walls containing a cylinder constructed of small lightweight spheres. The vertical bar on to the right of each frame shows the kinetic energy of the ball. To the right are 80 small objects representing a solid that will be crushed and vaporized through impact with the disk.

Christian, Wolfgang; Belloni, Mario

2006-01-13

335

ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis Project  

NASA Astrophysics Data System (ADS)

Fiscal year 1987 research activities and accomplishments for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division are presented. The project's technical activities were organized into three work elements. The Molecular Modeling and Applied Genetics work element includes modeling and simulation studies to verify a dynamic model of the enzyme carboxypeptidase; plasmid stabilization by chromosomal integration; growth and stability characteristics of plasmid-containing cells; and determination of optional production parameters for hyper-production of polyphenol oxidase. The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields, and lower separation energetics. The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the economics and energetics of a given biocatalyst process.

1988-03-01

336

Solid State Energy Conversion Alliance 2nd Annual Workshop Proceedings  

SciTech Connect

The National Energy Technology Laboratory (NETL) and the Pacific Northwest National Laboratory (PNNL) are pleased to provide the proceedings of the second annual Solid State Energy Conversion Alliance (SECA) Workshop held on March 29-30, 2001 in Arlington. The package includes the presentations made during the workshop, a list of participants, and the results of the breakout sessions. Those sessions covered stack materials and processes, power electronics, balance of plant and thermal integration, fuel processing technologies, and stack and system performance modeling. The breakout sessions have been reported as accurately as possible; however, due to the recording and transcription process errors may have occurred. If you note any significant omissions or wish to provide additional information, we welcome your comments and hope that all stakeholder groups will use the enclosed information in their planning endeavors.

National Energy Technology Laboratory

2001-03-30

337

OCEAN THERMAL ENERGY CONVERSION: AN OVERALL ENVIRONMENTAL ASSESSMENT  

SciTech Connect

Significant acccrmplishments in Ocean Thermal Energy Conversion (OTEC) technology have increased the probability of producing OTEC-derived power within this decade with subsequent large scale commercialization following by the turn of the century. Under U.S. Department of Energy funding, the Oceanic Engineering Operations of Interstate Electronics Corporation has prepared several OTEC Environmental Assessments over the past years, in particular, the OTEC Programmatic Environmental Assessment. The Programmatic EA considers several technological designs (open- and closed-cycle), plant configuratlons (land-based, moored, and plant-ship), and power usages (baseload electricity, ammonia and aluminum production). Potential environmental impacts, health and safetv issues and a status update of the institutional issues as they influence OTEC deployments, are included.

Sands, M.Dale

1980-08-01

338

Controlled cellular energy conversion in brown adipose tissue thermogenesis  

NASA Technical Reports Server (NTRS)

Brown adipose tissue serves as a model system for nonshivering thermogenesis (NST) since a) it has as a primary physiological function the conversion of chemical energy to heat; and b) preliminary data from other tissues involved in NST (e.g., muscle) indicate that parallel mechanisms may be involved. Now that biochemical pathways have been proposed for brown fat thermogenesis, cellular models consistent with a thermodynamic representation can be formulated. Stated concisely, the thermogenic mechanism in a brown fat cell can be considered as an energy converter involving a sequence of cellular events controlled by signals over the autonomic nervous system. A thermodynamic description for NST is developed in terms of a nonisothermal system under steady-state conditions using network thermodynamics. Pathways simulated include mitochondrial ATP synthesis, a Na+/K+ membrane pump, and ionic diffusion through the adipocyte membrane.

Horowitz, J. M.; Plant, R. E.

1978-01-01

339

Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance  

SciTech Connect

The water-endofullerene H{sub 2}O@C{sub 60} provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H{sub 2}O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H{sub 2}O molecules is catalysed by {sup 13}C nuclei present in the cages.

Mamone, Salvatore, E-mail: s.mamone@soton.ac.uk; Concistrè, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Denning, Mark; Carravetta, Marina; Whitby, Richard J.; Levitt, Malcolm H., E-mail: mhl@soton.ac.uk [School of Chemistry, University of Southampton, Southampton SO17 1BJ (United Kingdom); Lei, Xuegong; Li, Yongjun [Department of Chemistry, Columbia University, New York, New York 10027 (United States)] [Department of Chemistry, Columbia University, New York, New York 10027 (United States); Goh, Kelvin; Horsewill, Anthony J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)] [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2014-05-21

340

Energy Conversion Alternatives Study (ECAS) General Electric Phase I. Final report. Volume II. Advanced energy conversion systems. Part III. Direct energy conversion cycles. [Using coal or coal-derived fuels  

Microsoft Academic Search

A parametric study was performed to assist in the development of a data base for the comparison of advanced energy conversion systems for utility applications using coal or coal-derived fuels. Estimates of power plant performance (efficiency), capital cost, cost of electricity, natural resource requirements, and environmental intrusion characteristics were made for ten advanced conversion systems. This volume contains design data

J. C. Corman; R. B. Fleming; L. P. Harris; R. V. Pohl

1976-01-01

341

Kinetic simulation of the O-X conversion process in dense magnetized plasmas  

SciTech Connect

One scheme for heating a dense magnetized plasma core, such as in a tokamak, involves launching an ordinary (O) electromagnetic wave at the low density edge. It is converted to a reflected extraordinary (X) electromagnetic wave under certain conditions, and then transformed into an electron Bernstein wave able to reach high density regions inaccessible to most other waves. The O-X mode conversion is important in heating and diagnostic processes in different devices such as tokamaks, stellarators, and some types of pinches. The goal of this study has been to demonstrate that the kinetic particle-in-cell (PIC) scheme is suitable for modeling the O-X conversion process as the first step toward a more complete simulation of O-X-B heating. The O-X process is considered and simulated with a kinetic particle model for parameters of the TJ-II stellarator using the PIC code, XOOPIC. This code is able to model the non-monotonic density and the magnetic profile of the TJ-II stellarator. It can also statistically represent the self-consistent distribution function of the plasma, which has not been possible in previous fluid models. By considering the electric and magnetic components of launched and reflected waves, the O-mode and X-mode waves can be detected, and the O-X conversion can be demonstrated. In this work, the optimum angle for conversion efficiency, as predicted by the previous theory and experimentally confirmed, is used. Via considering the power of the launched O-mode wave and the converted X-mode wave, the efficiency of 63% for O-X conversion for the optimum theoretical launch angle of 47{sup ?} is obtained, which is in good agreement with efficiencies computed via full-wave simulations.

Ali Asgarian, M. [Physics Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of) [Physics Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States); Verboncoeur, J. P. [Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States)] [Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States); Parvazian, A. [Physics Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)] [Physics Department, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Trines, R. [STFC Rutherford Appleton Laboratory, Didcot (United Kingdom)] [STFC Rutherford Appleton Laboratory, Didcot (United Kingdom)

2013-10-15

342

Conversion of relic gravitational waves into photons in cosmological magnetic fields  

SciTech Connect

Conversion of gravitational waves into electromagnetic radiation is discussed. The probability of transformations of gravitons into photons in presence of cosmological background magnetic field is calculated at the recombination epoch and during subsequent cosmological stages. The produced electromagnetic radiation is concentrated in the X-ray part of the spectrum. It is shown that if the early Universe was dominated by primordial black holes (PBHs) prior to Big Bang Nucleosynthesis (BBN), the relic gravitons emitted by PBHs would transform to an almost isotropic background of electromagnetic radiation due to conversion of gravitons into photons in cosmological magnetic fields. Such extragalactic radiation could be noticeable or even dominant component of Cosmic X-ray Background.

Dolgov, Alexander D.; Ejlli, Damian, E-mail: dolgov@fe.infn.it, E-mail: ejlli@fe.infn.it [Dipartimento di Fisica e Scienze della Terra, Polo Scientifico e Tecnologico-Edificio C, Università degli Studi di Ferrara, Via Saragat 1, 44122 Ferrara (Italy)

2012-12-01

343

Understanding and tuning nanostructured materials for chemical energy conversion  

NASA Astrophysics Data System (ADS)

The conversion of energy that employs chemical reaction is termed chemical energy conversion. In my dissertation, I have focused on chemical energy conversion systems involving energetic materials and lithium ion batteries, where performance is strongly dependent on the properties of materials and their architecture. The objective of this study is to enhance our understanding and tuning of nanostructured materials that might find application toward energetic materials and electrode materials in lithium ion batteries. Rapid heating diagnostics tools, i.e. temperature-jump techniques, have been used to study the ignition of aluminum nanoparticles, nanothermite reaction mechanism and metal oxides nanoparticles decomposition under rapid heating conditions (˜105-106 K/s). Time-resolved mass spectra results support the hypothesis that Al containing species diffuse outwards through the oxide shell. Low effective activation energies were found for metal oxides nanoparticles decomposition at high heating rates, implying the mass transfer control at high heating rates. The role of oxygen release from oxidizer in nanothermite reactions have been examined for several different systems, including some using microsized oxidizer (i.e., nano-Al/micro-I 2O5). In particular, for periodate based nanothermites, direct evidence from high heating rate SEM and mass spectrometry results support that direct gas phase oxygen release from oxidizer decomposition is critical in its ignition and combustion. Efforts have also been made to synthesize nanostructured materials for nanoenergetic materials and lithium ion batteries applications. Hollow CuO spheres were synthesized by aerosol spray pyrolysis, employing a gas blowing mechanism for the formation of hollow structure during aerosol synthesis. The materials synthesized as oxidizers in nanothermite demonstrated superior performance, and of particular note, periodate salts based nanothermite demonstrated the best gas generating performance for nanothermite materials. Energetic composite nanofibrous mats (NC/Al-CuO, NC/Al-Fe2O3, and NC/Al-Bi2O3) were also prepared by an electrospinning method and evaluated for their combustion performance. Aerosol spray pyrolysis was employed to produce carbon coated CuO hollow spheres, Mn3O4 hollow spheres, and Fe2O 3 mesoporous spheres. These hollow/mesoporous spheres demonstrated superior electrochemical performance when used as anode materials in lithium ion batteries. The effects of the amorphous and crystal structures on the electrochemical performance and the structure evolution during electrochemical tests were also investigated.

Jian, Guoqiang

344

DIRECT ENERGY CONVERSION FISSION REACTOR FOR THE PERIOD JANUARY 1, 2002 THROUGH MARCH 31, 2002  

Microsoft Academic Search

Direct energy conversion is the only potential means for producing electrical energy from a fission reactor without the Carnot efficiency limitations. This project was undertaken by Sandia National Laboratories, Los Alamos National Laboratories, The University of Florida, Texas A&M University and General Atomics to explore the possibilities of direct energy conversion. Other means of producing electrical energy from a fission

L. C. BROWN

2002-01-01

345

Proceedings of the 30. intersociety energy conversion engineering conference. Volume 3  

Microsoft Academic Search

This conference provides a forum to present and discuss the engineering aspects of energy conversion, advanced and unconventional energy systems and devices, energy conversion and utilization, environmental issues and policy implications on research, development, and implementation of technologies. The solution for a sustainable future will lie in a mix of all of the available energy resources (renewable and non-renewable) and

D. Y. Goswami; L. D. Kannberg; S. Somasundaram; T. R. Mancini

1995-01-01

346

Proceedings of the 30. intersociety energy conversion engineering conference. Volume 1  

Microsoft Academic Search

This conference provides a forum to present and discuss the engineering aspects of energy conversion, advanced and unconventional energy systems and devices, energy conversion and utilization, environmental issues and policy implications on research, development, and implementation of technologies. The solution for a sustainable future will lie in a mix of all of the available energy resources (renewable and non-renewable) and

D. Y. Goswami; L. D. Kannberg; S. Somasundaram; T. R. Mancini

1995-01-01

347

Proceedings of the 30. intersociety energy conversion engineering conference. Volume 2  

Microsoft Academic Search

This conference provides a forum to present and discuss the engineering aspects of energy conversion, advanced and unconventional energy systems and devices, energy conversion and utilization, environmental issues and policy implications on research, development, and implementation of technologies. The solution for a sustainable future will lie in a mix of all of the available energy resources (renewable and non-renewable) and

D. Y. Goswami; L. D. Kannberg; S. Somasundaram; T. R. Mancini

1995-01-01

348

39610 Energy Conversion & Supply (6) 39611 Energy Demand &Utilization (6)  

E-print Network

Engineering 18618 Smart Grids & Fut. Elec. Energy Sys (12) TBA 18771 Linear Systems (12)MW2:304:20,F2 to Sustainable Engr (12)MW34:20 19472 Fund. Electric Pwr Sys (12/note MW3:304:20) 19638 (18618) Smart Grids & F:303:50 18630 Intro to Security & Policy (12) 18777 Complex LargeScale Dynamic Sys(12) 18649

McGaughey, Alan

349

Power Management, Energy Conversion and Energy Scavenging for Smart Systems  

Microsoft Academic Search

An integral part of the vision for ambient intelligence is the use of large numbers of wireless sensors in a “deploy and forget”\\u000a manner. The long term provision of energy to wireless sensor nodes poses a challenge to this vision. Today the provision of\\u000a power is almost exclusively by means of batteries. The trend in battery technology has been towards

Terence O’Donnell; Wensi Wang

350

Refractory materials for high-temperature thermoelectric energy conversion  

NASA Technical Reports Server (NTRS)

Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimaiation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT 1 is realizable. These materials are divided into two classes: (1) the rare-earth chalcogenides which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (2) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity.

Wood, C.; Emin, D.

1984-01-01

351

Energy Conversion Options for Advanced Radioisotope Power Systems  

NASA Astrophysics Data System (ADS)

Static and dynamic energy conversion technologies for Advanced Radioisotope Power Systems (ARPSs) are reviewed and their impact on the system's total mass and specific electrical power and the amount of 238PuO2 fuel needed for the heat source are assessed and compared. Conversion technologies considered are Segmented and cascaded Thermoelectric, Alkali-Metal Thermal-to-Electric Conversion, and Free Piston Stirling Engines (FPSEs) and, for comparison, SiGe thermoelectric. Estimates for a 100 We ARPS indicate that when using SiGe thermoelectric, operating between 1273 K and 573 K, 8 General Purpose Heat Source (GPHS) modules would be required and the system's specific power is ~ 4.6 We/kg. Using STE converters, operating between 973 K and 373 K, 5 GPHS modules are required and the ARPS's specific power is ~ 7.28 We/kg. The next generation STE converters that could operate between 1273 K and 573 K, for a projected system efficiency of 13.8%, decrease the number of GPHS modules needed to 4 and increase the system's specific power to ~ 9.9 We/kg. With cascaded SiGe-STE converters, operating between 1273 K and 373 K, the system's efficiency could be as much as 16%, requiring only 3 GPHS modules, for an estimated specific power of 10.7 We/kg. This specific power is more than twice that for SOA RTG. With the current version 1.0 of FPSEs, the 100 We ARPS needs only two GPHS modules, but its specific power (4.1 we/kg) is slightly lower than that of SOA RTG (4.6 We/kg). Future introduction of versions 1.1 and 2.0 engines, with slightly higher conversion efficiency and significantly lower mass, could increase the system's specific power to ~ 7.5 We/kg, using the same number of GPHS modules as version 1.0 engines. With Na-AMTEC and K-AMTEC, the 100 We ARPS needs 3 and 4 GPHS modules, respectively, for an estimated specific power of 5.3 and 5.8 We/kg, respectively.

El-Genk, Mohamed S.

2003-01-01

352

Direct voltage control for standalone wind energy conversion systems with induction generator and energy storage  

Microsoft Academic Search

A control method for standalone wind energy conversion systems with induction generator and energy storage system (ESS) is proposed in this paper. A fixed-speed self-excited induction generator is directly connected to the standalone power system. An ESS is employed to compensate the power variation from wind generator and load, maintain the power flow balanced. A direct voltage control scheme is

Wei Huang; D. W. Xu

2008-01-01

353

Wave Energy Conversion Overview and it's Renewable Energy Potential for the Oil and Gas Industry  

E-print Network

Ocean energy conversion has been of interest for many years. Recent developments such as concern over global warming have renewed interest in the topic. Part II provides an overview of the energy density found in ocean waves and how it is calculated...

Pastor, J.; Liu, Y.; Dou, Y.

2014-01-01

354

Review of pyroelectric thermal energy harvesting and new MEMs based resonant energy conversion techniques  

SciTech Connect

Harvesting electrical energy from thermal energy sources using pyroelectric conversion techniques has been under investigation for over 50 years, but it has not received the attention that thermoelectric energy harvesting techniques have during this time period. This lack of interest stems from early studies which found that the energy conversion efficiencies achievable using pyroelectric materials were several times less than those potentially achievable with thermoelectrics. More recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. This paper will review the recent history in this field and describe the techniques that are being developed to increase the opportunities for pyroelectric energy harvesting. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, are also outlined. The approach uses a resonantly driven, pyroelectric capacitive bimorph cantilever structure that can be used to rapidly cycle the temperature in the energy harvester. The device has been modeled using a finite element multi-physics based method, where the effect of the structure material properties and system parameters on the frequency and magnitude of temperature cycling, and the efficiency of energy recycling using the proposed structure, have been modeled. Results show that thermal contact conductance and heat source temperature differences play key roles in dominating the cantilever resonant frequency and efficiency of the energy conversion technique. This paper outlines the modeling, fabrication and testing of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy conversion devices.

Hunter, Scott Robert [ORNL; Lavrik, Nickolay V [ORNL; Mostafa, Salwa [ORNL; Rajic, Slobodan [ORNL; Datskos, Panos G [ORNL

2012-01-01

355

Methods of energy conversion \\/Some results of the International Electrotechnology Congress - Moscow, 1977  

Microsoft Academic Search

Several papers dealing with direct energy conversion are reviewed. The review, divided into two sections, focuses on such physical methods of conversion as photoelectric, thermoelectric and thermionic power generation and also considers methods of electrochemical power generation. Attention is also given to the technology of thyristors and semiconductor diodes, to methods of data conversion, and to new current generators. Bibtex

N. S. Lidorenko

1978-01-01

356

Shelf mounted ocean thermal energy conversion platform, revised preliminary report  

NASA Astrophysics Data System (ADS)

This report relates model tests of a generic Ocean Thermal Energy Conversion (OTEC) platform. The objective of these tests is to aid in the evaluation of new OTEC designs and to present a data base for design purposes. The test plant has been designed to provide a data base for comparison with current and projected analytical tools as well as comparisons of results from one model configuration to another. The new conceptual OTEC designs are different from the typical offshore (jacket type) structure which is quite transparent to waves. The major difference is the addition of large submerged power production modules to the frame. These proposed modules offer a large surface area to obstruct the flow and thereby increase the global wave forces acting on the structure.

1984-03-01

357

High-temperature thermoelectric energy conversion. II - Materials survey  

NASA Technical Reports Server (NTRS)

The current status of materials research for high-temperature thermoelectric energy conversion is reviewed. Two general classes of materials show promise for high temperature figure of merit (Z) values, viz, the rare-earth chalcogenides and the boron-rich borides. The electronic transport properties of the rare-earth chalcogenides are explicable on the basis of degenerate or partially degenerate n-type semiconductors. Boron and boron-rich borides exhibit p-type hopping conductivity, with detailed explanations proposed for the transport differing from compound to compound. Some discussion is presented on the reasons for the low thermal conductivities in these materials. Also, ZTs greater than one appear to have been realized at high temperature in many of these compounds.

Wood, C.

1984-01-01

358

Tandem photovoltaic solar cells and increased solar energy conversion efficiency  

NASA Technical Reports Server (NTRS)

Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.

Loferski, J. J.

1976-01-01

359

Monolithic Interconnected Modules (MIMs) for Thermophotovoltaic Energy Conversion  

NASA Technical Reports Server (NTRS)

Monolithic Interconnected Modules (MIM) are under development for thermophotovoltaic (TPV) energy conversion applications. MIM devices are typified by series-interconnected photovoltaic cells on a common, semi-insulating substrate and generally include rear-surface infrared (IR) reflectors. The MIM architecture is being implemented in InGaAsSb materials without semi-insulating substrates through the development of alternative isolation methodologies. Motivations for developing the MIM structure include: reduced resistive losses, higher output power density than for systems utilizing front surface spectral control, improved thermal coupling and ultimately higher system efficiency. Numerous design and material changes have been investigated since the introduction of the MIM concept in 1994. These developments as well as the current design strategies are addressed.

Wilt, David; Wehrer, Rebecca; Palmisiano, Marc; Wanlass, Mark; Murray, Christopher

2003-01-01

360

Magnetic Energy Production by Turbulence in Binary Neutron Star Mergers  

NASA Astrophysics Data System (ADS)

The simultaneous detection of electromagnetic and gravitational wave emission from merging neutron star binaries would greatly aid in their discovery and interpretation. By studying turbulent amplification of magnetic fields in local high-resolution simulations of neutron star merger conditions, we demonstrate that magnetar-level (gsim 1016 G) fields are present throughout the merger duration. We find that the small-scale turbulent dynamo converts 60% of the randomized kinetic energy into magnetic fields on a merger timescale. Since turbulent magnetic energy dissipates through reconnection events that accelerate relativistic electrons, turbulence may facilitate the conversion of orbital kinetic energy into radiation. If 10-4 of the ~1053 erg of orbital kinetic available gets processed through reconnection and creates radiation in the 15-150 keV band, then the fluence at 200 Mpc would be 10-7 erg cm-2, potentially rendering most merging neutron stars in the advanced LIGO and Virgo detection volumes detectable by Swift BAT.

Zrake, Jonathan; MacFadyen, Andrew I.

2013-06-01

361

Wind energy conversion based on seven-level cascaded H-bridge inverter using LabVIEW FPGA  

Microsoft Academic Search

In this paper, an isolated wind energy conversion system (WECS) based on the cascaded H-bridge multilevel inverter (CHBMLI) topology employing a permanent magnet synchronous generator (PMSG) driven by a variable speed wind turbine and feeding high power single-phase local loads has been proposed. A seven-level cascaded H-bridge inverter employing phase-shifted multi-carrier pulse width modulation is implemented using LabVIEW FPGA. The

Paulson Samuel; Nalamati Chandrashekhar; Rajesh Gupta

2010-01-01

362

Calculation of electrostatic wave conversion in a transition layer of magnetized plasma near the upper hybrid resonance  

Microsoft Academic Search

A rigorous solution is derived for the problem of the conversion of cold, short plasma waves in a model transition layer of magnetized plasma in which the density profile is described by two parabolas which join at the point of the plasma resonance. The intensity of the conversion is studied as a function of the width of the transition layer

V. V. Vaskov; V. A. Puchkov

1985-01-01

363

Sustainable systems for the storage and conversion of energy are dependent on interconnected  

E-print Network

framework, the development of new sustainable energy technologies for applications including high systems, and sustainable energy portfolios has resulted in over 20 archival journal and conferenceSEMTE abstract Sustainable systems for the storage and conversion of energy are dependent

Reisslein, Martin

364

M13 bacteriophage-enabled assembly of nanocomposites : synthesis and application in energy conversion devices  

E-print Network

Lack of energy supply and non-uniform distribution of traditional energy sources, such as coal, oil, and natural gas, have brought up tremendous social issues. To solve these issues, highly efficient energy conversion ...

Dang, Xiangnan

2013-01-01

365

Ocean Thermal Energy Conversion Primer L. A. Vega, Ph.D.  

E-print Network

Ocean Thermal Energy Conversion Primer L. A. Vega, Ph.D. PICHTR Honolulu, HI ABSTRACT The vertical engine) designed to transform the thermal energy into electricity. This is referred to as OTEC for Ocean Thermal Energy Conversion. Several techniques have been proposed to use this ocean thermal resource

366

THE CONVERSION OF BIOMASS TO ETHANOL USING GEOTHERMAL ENERGY DERIVED FROM HOT DRY ROCK  

E-print Network

97505 THE CONVERSION OF BIOMASS TO ETHANOL USING GEOTHERMAL ENERGY DERIVED FROM HOT DRY ROCK between a hot dry rock (HDR) geothermal energy source and the power requirements for the conversion -- geothermal energy derived from the vast resource of Hot Dry Rock (HDR) in our country, and biomass

367

A Unified Framework for Reliability Assessment of Wind Energy Conversion Systems  

E-print Network

based on wind energy are: the impact of wind speed variability on system reliability [1]; WECS' reaction1 A Unified Framework for Reliability Assessment of Wind Energy Conversion Systems Sebastian S a framework for assessing wind energy conversion systems (WECS) reliability in the face of external

Liberzon, Daniel

368

2012: ME 533-Energy Conversion Dr. William M. Carey, Professor of Mechanical Engineering  

E-print Network

of Energy Technologies -Nuclear, Solar, Wind, Oceanic and Fossil Fuels. 3.) Provide an analytical frame work and Ideal Gas Mixtures. 3) Energy Conversion systems-Coal-Oil-Nuclear, Oceanic, Solar, Geothermal and Wind of environmental impact, and 7.)a concise presentation of the results. Energy Conversion Paper: Students

369

Volume 28A, number 2 PHYSICS LETTERS 4 November 1968 HIGH ENERGY K CONVERSION COEFFICIENTS  

E-print Network

Volume 28A, number 2 PHYSICS LETTERS 4 November 1968 HIGH ENERGY K CONVERSION COEFFICIENTS C. 0V) Fig. 1. Theoretical values for K conversion coefficients for 2 = 48. gamma-ray transition energies 1 and Astronomy: Louisiana State University, Baton Rouge, Louisiana. USA Received 21 September 1968 High energy K

O'Connell, Robert F.

370

Thermal Sciences The thermal sciences area involves the study of energy conversion and transmission, power  

E-print Network

in virtually all energy conversion devices and systems. One may think of the jet engine as a mechanical deviceThermal Sciences The thermal sciences area involves the study of energy conversion and transmission, power generation, the flow of liquids and gases, and the transfer of thermal energy (heat) by means

New Hampshire, University of

371

Soft Magnetic Materials in High-Frequency, High-Power Conversion Applications  

E-print Network

of renewable energy sources and distributed storage systems requires new topologies to handle transient sources and facilitate two-way power conversion.7 Flexible alternating current (AC) Transmission Systems (FACTS) and High topologies containing high-frequency DC­DC power converters.9­13 Independent of the power generation method

McHenry, Michael E.

372

Thermal energy conversion by coupled shape memory and piezoelectric effects  

NASA Astrophysics Data System (ADS)

This work gives experimental evidence of a promising method of thermal-to-electric energy conversion by coupling shape memory effect (SME) and direct piezoelectric effect (DPE) for harvesting quasi-static ambient temperature variations. Two original prototypes of thermal energy harvesters have been fabricated and tested experimentally. The first is a hybrid laminated composite consisting of TiNiCu shape memory alloy (SMA) and macro fiber composite piezoelectric. This composite comprises 0.1 cm3 of active materials and harvests 75 µJ of energy for each temperature variation of 60 °C. The second prototype is a SME/DPE ‘machine’ which uses the thermally induced linear strains of the SMA to bend a bulk PZT ceramic plate through a specially designed mechanical structure. The SME/DPE ‘machine’ with 0.2 cm3 of active material harvests 90 µJ over a temperature increase of 35 °C (60 µJ when cooling). In contrast to pyroelectric materials, such harvesters are also compatible with both small and slow temperature variations.

Zakharov, Dmitry; Lebedev, Gor; Cugat, Orphee; Delamare, Jerome; Viala, Bernard; Lafont, Thomas; Gimeno, Leticia; Shelyakov, Alexander

2012-09-01

373

Photo-mechanical energy conversion using polymer brush dissociation  

E-print Network

A device is investigated that continuously and directly converts light into mechanical energy, using polymers and photodissociation. A polymer brush tethered to a surface, is brought into contact with a parallel plate a small distance above it that contains reaction sites where photodissociation of bound polymer and light can occur. Under the appropriate conditions, the collective effect of these polymers is to apply a force parallel to the plates, converting incoming light into mechanical work. Numerical work is carried out to understand this effect, a three dimensional Langevin simulation, solution to the Fokker Planck equation, and a one dimensional Monte Carlo simulation. Theoretical analysis of the Fokker Planck equation is used to study a model where equilibration of the unbound state occurs and equilibration to a metastable equilibrium is achieved in the bound state. It is shown that the work per cycle can be made much larger than the thermal energy but at the expense of requiring a greatly diminished photodissociation rate. Parameters are discussed in order optimize mechanical energy conversion.

J. M. Deutsch

2013-01-03

374

Transmission and Conversion of Energy by Coupled Soft Gears  

E-print Network

Dynamical aspects of coupled deformable gears are investigated to clarify the differences of mechanical properties between the machines consist of hard materials and those of soft materials. In particular, the performances of two functions, the transmission and the conversion of the energy, are compared between the hard and soft gears systems. First, the responses of the coupled gears against a constant torque working on one of gears are focused for two types of couplings; P) a pair gears are coupled, and T) three gears are coupled with forming a regular triangle. In systems with the coupling P), we obtain trivial results that the rotational energy can be transmitted to other gear only if these gears are hard enough. On the other hand, in systems with the coupling T), the transmission of the rotational energy to one of the other gears appears only if these gears are soft enough. Second, we show the responses of this system in which one of gears have contact with a high temperature heat bath and the other gears have contact with a 0 temperature heat bath. With the coupling T), the directional rotations appear in two gears having contact with 0 temperature heat bath. Here, the direction of these rotations change depending on the noise strength.

Akinori Awazu

2005-03-15

375

Symposium on the Physical Chemistry of Solar Energy Conversion, Indianapolis American Chemical Society Meetings, Fall 2013  

SciTech Connect

The Symposium on the Physical Chemistry of Solar Energy Conversion at the Fall ACS Meeting in Indianapolis, IN (Sept. 8-12) featured the following sessions (approx. 6 speakers per session): (1) Quantum Dots and Nanorods for Solar Energy Conversion (2 half-day sessions); (2) Artificial Photosynthesis: Water Oxidation; (3) Artificial Photosynthesis: Solar Fuels (2 half-day sessions); (4) Organic Solar Cells; (5) Novel Concepts for Solar Energy Conversion (2 half-day sessions); (6) Emerging Techniques for Solar Energy Conversion; (7) Interfacial Electron Transfer

Lian, Tianquan [PI, Emory Univ.

2013-09-01

376

Advanced Energy Conversion Technologies and Architectures for Earth and Beyond  

NASA Technical Reports Server (NTRS)

Research, development and studies of novel space-based solar power systems, technologies and architectures for Earth and beyond are needed to reduce the cost of clean electrical power for terrestrial use and to provide a stepping stone for providing an abundance of power in space, i.e., manufacturing facilities, tourist facilities, delivery of power between objects in space, and between space and surface sites. The architectures, technologies and systems needed for space to Earth applications may also be used for in-space applications. Advances in key technologies, i.e., power generation, power management and distribution, power beaming and conversion of beamed power are needed to achieve the objectives of both terrestrial and extraterrestrial applications. There is a need to produce "proof-ofconcept" validation of critical WPT technologies for both the near-term, as well as far-term applications. Investments may be harvested in near-term beam safe demonstrations of commercial WPT applications. Receiving sites (users) include ground-based stations for terrestrial electrical power, orbital sites to provide power for satellites and other platforms, future space elevator systems, space vehicle propulsion, and space surface sites. Space surface receiving sites of particular interest include the areas of permanent shadow near the moon s North and South poles, where WPT technologies could enable access to ice and other useful resources for human exploration. This paper discusses work addressing a promising approach to solar power generation and beamed power conversion. The approach is based on a unique high-power solar concentrator array called Stretched Lens Array (SLA) applied to both solar power generation and beamed power conversion. Since both versions (solar and laser) of SLA use many identical components (only the photovoltaic cells need to be different), economies of manufacturing and scale may be realized by using SLA on both ends of the laser power beaming system in a space solar power application. Near-term uses of this SLA-laser-SLA system may include terrestrial and space exploration in near Earth space. Later uses may include beamed power for bases or vehicles on Mars. Strategies for developing energy infrastructures in space which utilize this technology are presented. This dual use system produces electrical energy efficiently from either coherent light, such as from a highly coherent laser, or from conventional solar illumination. This allows, for example, supplementing solar energy with energy provided by highly coherent laser illumination during periods of low solar illumination or no illumination. This reduces the need for batteries and alternate sources of power. The capability of using laser illumination in a lowest order Gaussian laser mode provides means for transmitting power optically with maximum efficiency and precision over the long distances characteristic of space. A preliminary receiving system similar to that described here, has been produced and tested under solar and laser illumination. A summary of results is given.

Howell, Joe T.; Fikes, John C.; Phillips, Dane J.; Laycock, Rustin L.; ONeill, Mark; Henley, Mark W.; Fork, Richard L.

2006-01-01

377

Ocean thermal energy conversion: Historical highlights, status, and forecast  

SciTech Connect

In 1881, d'Arsonval conceived the closed-Rankine-cycle ocean thermal energy conversion (OTEC) system in which a working fluid is vaporized by heat exchange with cold water drawn from a 700-1200 m depth. In 1930, Claude demonstrated an open-cycle process in Cuba. Surface water was flash-vaporized at 3 kPa to drive a turbine directly (no secondary working fluid) and then was condensed by direct contact with water drawn from a 700-m depth through a 1.6m-diam, 1.75-km-long cold-water pipe (CWP). From a delta T of 14/sup 0/C his undersized turbine generated 22 kW. In 1956 a French team designed a 3.5-MW (net) open-cycle plant for installation off Abidjan on the Ivory Coast of Africa and demonstrated the necessary CWP deployment. The at-sea demonstrations by Mini-OTEC and OTEC-1 and other recent advances in OTEC technology summarized herein represent great progress. All of the types of plants proposed for the DOE's PON program may be worthy of development; certainly work on a grazing plant is needed. Our estimates indicate that the U.S. goals established by Public Law 96-310 leading to 10 GW of OTEC power and energy product equivalents by 1999 are achievable, provided that adequate federal financial incentives are retained to assure the building of the first few plants.

Dugger, G.L.; Avery, W.H.; Francis, E.J.; Richards, D.

1983-07-01

378

Environmental programs for ocean thermal energy conversion (OTEC)  

SciTech Connect

The environmental research effort in support of the US Department of Energy's Ocean Thermal Energy Conversion (OTEC) program has the goal of providing documented information on the effect of proposed operations on the ocean and the effect of oceanic conditions on the plant. The associated environment program consists of archival studies in potential areas serial oceanographic cruises to sites or regions of interest, studies from various fixed platforms at sites, and compilation of such information for appropriate legal compliance and permit requirements and for use in progressive design of OTEC plants. Site/regions investigated are south of Mobile and west of Tampa, Gulf of Mexico; Punta Tuna, Puerto Rico; St. Croix, Virgin Islands; Kahe Point, Oahu and Keahole Point, Hawaii, Hawaiian Islands; and off the Brazilian south Equatorial Coast. Four classes of environmental concerns identified are: redistribution of oceanic properties (ocean water mixing, impingement/entrainment etc.); chemical pollution (biocides, working fluid leaks, etc.); structural effects (artificial reef, aggregation, nesting/migration, etc.); socio-legal-economic (worker safety, enviromaritime law, etc.).

Wilde, P.

1981-07-01

379

Energy Conversion Advanced Heat Transport Loop and Power Cycle  

SciTech Connect

The Department of Energy and the Idaho National Laboratory are developing a Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is two fold 1) efficient low cost energy generation and 2) hydrogen production. Although a next generation plant could be developed as a single-purpose facility, early designs are expected to be dual-purpose. While hydrogen production and advanced energy cycles are still in its early stages of development, research towards coupling a high temperature reactor, electrical generation and hydrogen production is under way. Many aspects of the NGNP must be researched and developed in order to make recommendations on the final design of the plant. Parameters such as working conditions, cycle components, working fluids, and power conversion unit configurations must be understood. Three configurations of the power conversion unit were demonstrated in this study. A three-shaft design with 3 turbines and 4 compressors, a combined cycle with a Brayton top cycle and a Rankine bottoming cycle, and a reheated cycle with 3 stages of reheat were investigated. An intermediate heat transport loop for transporting process heat to a High Temperature Steam Electrolysis (HTSE) hydrogen production plant was used. Helium, CO2, and an 80% nitrogen, 20% helium mixture (by weight) were studied to determine the best working fluid in terms cycle efficiency and development cost. In each of these configurations the relative component size were estimated for the different working fluids. The relative size of the turbomachinery was measured by comparing the power input/output of the component. For heat exchangers the volume was computed and compared. Parametric studies away from the baseline values of the three-shaft and combined cycles were performed to determine the effect of varying conditions in the cycle. This gives some insight into the sensitivity of these cycles to various operating conditions as well as trade offs between efficiency and capital cost. Prametric studies were carried out on reactor outlet temperature, mass flow, pressure, and turbine cooling. Recommendations on the optimal working fluid for each configuration were made. A steady state model comparison was made with a Closed Brayton Cycle (CBC) power conversion system developed at Sandia National Laboratory (SNL). A preliminary model of the CBC was developed in HYSYS for comparison. Temperature and pressure ratio curves for the Capstone turbine and compressor developed at SNL were implemented into the HYSYS model. A comparison between the HYSYS model and SNL loop demonstrated power output predicted by HYSYS was much larger than that in the experiment. This was due to a lack of a model for the electrical alternator which was used to measure the power from the SNL loop. Further comparisons of the HYSYS model and the CBC data are recommended. Engineering analyses were performed for several configurations of the intermediate heat transport loop that transfers heat from the nuclear reactor to the hydrogen production plant. The analyses evaluated parallel and concentric piping arrangements and two different working fluids, including helium and a liquid salt. The thermal-hydraulic analyses determined the size and insulation requirements for the hot and cold leg pipes in the different configurations. Economic analyses were performed to estimate the cost of the va

Oh, C. H.

2006-08-01

380

Energy Magnetization and the Thermal Hall Effect  

NASA Astrophysics Data System (ADS)

We obtain a set of general formulas for determining magnetizations, including the usual electromagnetic magnetization as well as the gravitomagnetic energy magnetization. The magnetization corrections to the thermal transport coefficients are explicitly demonstrated. Our theory provides a systematic approach for properly evaluating the thermal transport coefficients of magnetic systems, eliminating the unphysical divergence from the direct application of the Kubo formula. For a noninteracting anomalous Hall system, the corrected thermal Hall conductivity obeys the Wiedemann-Franz law.

Qin, Tao; Niu, Qian; Shi, Junren

2011-12-01

381

Energy magnetization and the thermal Hall effect.  

PubMed

We obtain a set of general formulas for determining magnetizations, including the usual electromagnetic magnetization as well as the gravitomagnetic energy magnetization. The magnetization corrections to the thermal transport coefficients are explicitly demonstrated. Our theory provides a systematic approach for properly evaluating the thermal transport coefficients of magnetic systems, eliminating the unphysical divergence from the direct application of the Kubo formula. For a noninteracting anomalous Hall system, the corrected thermal Hall conductivity obeys the Wiedemann-Franz law. PMID:22182111

Qin, Tao; Niu, Qian; Shi, Junren

2011-12-01

382

Forced Reconnection in the Near Magnetotail: Onset and Energy Conversion in PIC and MHD Simulations  

NASA Technical Reports Server (NTRS)

Using two-dimensional particle-in-cell (PIC) together with magnetohydrodynamic (MHD) Q1 simulations of magnetotail dynamics, we investigate the evolution toward onset of reconnection and the subsequent energy transfer and conversion. In either case, reconnection onset is preceded by a driven phase, during which magnetic flux is added to the tail at the high-latitude boundaries, followed by a relaxation phase, during which the configuration continues to respond to the driving. The boundary deformation leads to the formation of thin embedded current sheets, which are bifurcated in the near tail, converging to a single sheet farther out in the MHD simulations. The thin current sheets in the PIC simulation are carried by electrons and are associated with a strong perpendicular electrostatic field, which may provide a connection to parallel potentials and auroral arcs and an ionospheric signal even prior to the onset of reconnection. The PIC simulation very well satisfies integral entropy conservation (intrinsic to ideal MHD) during this phase, supporting ideal ballooning stability. Eventually, the current intensification leads to the onset of reconnection, the formation and ejection of a plasmoid, and a collapse of the inner tail. The earthward flow shows the characteristics of a dipolarization front: enhancement of Bz, associated with a thin vertical electron current sheet in the PIC simulation. Both MHD and PIC simulations show a dominance of energy conversion from incoming Poynting flux to outgoing enthalpy flux, resulting in heating of the inner tail. Localized Joule dissipation plays only a minor role.

Birn, J.; Hesse, Michael

2014-01-01

383

Investigation and development of new materials for electrochemical energy conversion  

NASA Astrophysics Data System (ADS)

Performance of next generation electrochemical energy conversion devices relies on optimization of both ion selective membranes that retain conductivity at elevated temperatures, and electrode materials active and stable in corrosive environment. The work presented focuses on (1) improving energy conversion in fuel cells by designing novel ion conductive membrane materials optimized by an original optical high-throughput screening technique and (2) development of new stable mixed transition metal sulfide electrocatalysts for industrial bromine recovery. A functionalized fullerene derivative was used to fabricate mechanically strong, flexible organic-inorganic membranes via cooperative sol-gel synthesis. Amorphous materials with nanometer range wormlike structures were obtained. The dependence of conductivity on the concentration of triflic acid was quantitatively described by percolation theory. Fullerene derivatives with arbitrarily attached chains increased disorder of the structure, but before the wormlike network collapsed conductivity 40 times higher than that of the sample with no fullerenes was recorded. This enhancement was attributed to the additional inter-channel connections for proton transport facilitated by the fullerene derivatives. Optimization of the structure by an optical high-throughput screening made possible proton conductivity of 3.2x10-3 S/cm at 130°C and 5% humidity conditions. A series of doped Ru, Fe, Mo, W sulfide catalysts was synthesized, and their hydrogen evolution and oxygen reduction activity in HBr were studied as a function of dopant. RuS2 compounds showed the highest rates of hydrogen evolution and oxygen reduction reactions in HBr. Among all dopants, Co was the most active for hydrogen evolution reaction with overpotentials 100 mV lower than that of Pt at current density of 80 mA/cm2 in 0.5 M HBr. Oxygen reduction activity of RuS2 catalysts was found to change consistently as a function of periodic position of a dopant. Cr, Mn and Fe dopants inhibited oxygen reduction activity of RuS2, while Co, Ni and Cu promoted the activity. Inexpensive Ni-W sulfide was identified as active catalyst for oxygen reduction reaction in HBr. The activity increased with the addition of Ni up to 50%. Although Co-doped RuS2 is unstable in 6 M HBr, it was found to be stable under applied potential during 5 hour hydrogen evolution reaction test.

Ivanovskaya, Anna

384

ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis project  

NASA Technical Reports Server (NTRS)

The Annual Report presents the fiscal year (FY) 1988 research activities and accomplishments, for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division. The ECUT Biocatalysis Project is managed by the Jet Propulsion Laboratory, California Institute of Technology. The Biocatalysis Project is a mission-oriented, applied research and exploratory development activity directed toward resolution of the major generic technical barriers that impede the development of biologically catalyzed commercial chemical production. The approach toward achieving project objectives involves an integrated participation of universities, industrial companies and government research laboratories. The Project's technical activities were organized into three work elements: (1) The Molecular Modeling and Applied Genetics work element includes research on modeling of biological systems, developing rigorous methods for the prediction of three-dimensional (tertiary) protein structure from the amino acid sequence (primary structure) for designing new biocatalysis, defining kinetic models of biocatalyst reactivity, and developing genetically engineered solutions to the generic technical barriers that preclude widespread application of biocatalysis. (2) The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields and lower separation energetics. Results of work within this work element will be used to establish the technical feasibility of critical bioprocess monitoring and control subsystems. (3) The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the energy-economics of biocatalyzed chemical production processes, and initiation of technology transfer for advanced bioprocesses.

Baresi, Larry

1989-01-01

385

Direct Energy Conversion for Nuclear Propulsion at Low Specific Mass  

NASA Technical Reports Server (NTRS)

The project will continue the FY13 JSC IR&D (October-2012 to September-2013) effort in Travelling Wave Direct Energy Conversion (TWDEC) in order to demonstrate its potential as the core of a high potential, game-changing, in-space propulsion technology. The TWDEC concept converts particle beam energy into radio frequency (RF) alternating current electrical power, such as can be used to heat the propellant in a plasma thruster. In a more advanced concept (explored in the Phase 1 NIAC project), the TWDEC could also be utilized to condition the particle beam such that it may transfer directed kinetic energy to a target propellant plasma for the purpose of increasing thrust and optimizing the specific impulse. The overall scope of the FY13 first-year effort was to build on both the 2012 Phase 1 NIAC research and the analysis and test results produced by Japanese researchers over the past twenty years to assess the potential for spacecraft propulsion applications. The primary objective of the FY13 effort was to create particle-in-cell computer simulations of a TWDEC. Other objectives included construction of a breadboard TWDEC test article, preliminary test calibration of the simulations, and construction of first order power system models to feed into mission architecture analyses with COPERNICUS tools. Due to funding cuts resulting from the FY13 sequestration, only the computer simulations and assembly of the breadboard test article were completed. The simulations, however, are of unprecedented flexibility and precision and were presented at the 2013 AIAA Joint Propulsion Conference. Also, the assembled test article will provide an ion current density two orders of magnitude above that available in previous Japanese experiments, thus enabling the first direct measurements of power generation from a TWDEC for FY14. The proposed FY14 effort will use the test article for experimental validation of the computer simulations and thus complete to a greater fidelity the mission analysis products originally conceived for FY13.

Scott, John H.

2014-01-01

386

Analysis of Energy Conversion Systems, Including Material and Global Warming Aspects  

Microsoft Academic Search

This paper addresses a method for the overall evaluation of energy conversion systems, including material and global environmental aspects. To limit the scope of the work reported here, the global environmental aspects have been limited to global warming aspects.A method is presented that uses exergy as an overall evaluation measure of energy conversion systems for their lifetime. The method takes

Mingyuan Zhang; Gordon M. Reistad

1998-01-01

387

AC conductivity of nanoporous metal-oxide photoanodes for solar energy conversion  

E-print Network

AC conductivity of nanoporous metal-oxide photoanodes for solar energy conversion Steven J. Konezny% solar-to-electric energy conversion efficiency) exploited the large surface area of nanoporous thin for solar photoconversion is analyzed using a model based on fluctuation-induced tunneling conduction (FITC

Konezny, Steven J.

388

Power system dynamics influenced by a power electronic interface for variable speed wind energy conversion systems  

Microsoft Academic Search

A study of the influence of a wind energy conversion system on power system dynamics is presented in this paper. The wind energy conversion system is interfaced into a power system through a power electronic system including a voltage source converter (VSC) at the grid side. This paper investigates the system performance during a power system disturbance; a voltage sag

Z. Chen; Y. Hu

2004-01-01

389

Performance and economics of advanced energy conversion systems for coal and coal-derived fuels  

Microsoft Academic Search

The desire to establish an efficient Energy Conversion System to utilize the fossil fuel of the future - coal - has produced many candidate systems. A comparative technical\\/economic evaluation was performed on the seven most attractive advanced energy conversion systems. The evaluation maintains a cycle-to-cycle consistency in both performance and economic projections. The technical information base can be employed to

J. C. Corman; G. R. Fox

1978-01-01

390

Frster resonance energy transfer enhanced color-conversion using colloidal semiconductor quantum dots for solid  

E-print Network

Förster resonance energy transfer enhanced color-conversion using colloidal semiconductor quantum August 2009; published online 15 October 2009 In this paper, we present Förster resonance energy transfer FRET -enhanced color-conversion using colloidal semiconductor quantum dot nanocrystals NCs to make

Demir, Hilmi Volkan

391

PHYSICAL REVIEW C 81, 024326 (2010) Resonance behavior of internal conversion coefficients at low -ray energy  

E-print Network

February 2010) A resonance-like structure of internal conversion coefficients (ICCs) at low -ray energyPHYSICAL REVIEW C 81, 024326 (2010) Resonance behavior of internal conversion coefficients at low -ray energy M. B. Trzhaskovskaya,1 T. Kib´edi,2 and V. K. Nikulin3 1 Petersburg Nuclear Physics

392

Space nuclear reactor power system concepts with static and dynamic energy conversion  

Microsoft Academic Search

Nuclear reactor power systems could revolutionize space exploration and support human outpost on the Moon and Mars. This paper reviews current static and dynamic energy conversion technologies for use in space reactor power systems and provides estimates of the system’s net efficiency and specific power, and the specific area of the radiator. The suitable combinations of the energy conversion technologies

Mohamed S. El-Genk

2008-01-01

393

Energy conversion system optimization study for multimegawatt space nuclear power applications  

Microsoft Academic Search

The major objective of this paper is to present a detailed description of the energy conversion system analysis and optimization procedures that were part of a broader preliminary study aimed at designing a multimegawatt (MMW) space nuclear power system. In optimizing the energy conversion system it is assumed that the most massive component of the system is the radiator and

A. G. Parlos; M. S. El-Genk; J. M. McGhee; D. Buden; J. Mims

1988-01-01

394

Conference Chair: Dr. Matthew Mench Condra Chair of Excellence in Energy Conversion & Storage  

E-print Network

Conference Chair: Dr. Matthew Mench Condra Chair of Excellence in Energy Conversion & Storage Dept Electrochemical Energy Storage and Conversion Forum April 19-20 Knoxville, Tennessee Proudly sponsored by. of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee Joint Faculty at ORNL mmench

Tennessee, University of

395

Nanoscale Triboelectric-Effect-Enabled Energy Conversion for Sustainably Powering Portable Electronics  

E-print Network

Nanoscale Triboelectric-Effect-Enabled Energy Conversion for Sustainably Powering Portable , and 128 mW/cm3 , respectively, and an energy conversion efficiency as high as 10-39% has been demonstrated Electronics Sihong Wang,,§ Long Lin,,§ and Zhong Lin Wang,, * School of Materials Science and Engineering

Wang, Zhong L.

396

Nanomaterials of silicides and silicon for energy conversion and storage  

Microsoft Academic Search

Our consumption of fossil fuels can be reduced to address the pressing concerns of global climate change by maximizing the efficiency of conversion technologies. Since many of the alternative fuel sources also being examined are intermittent in nature, it is imperative that high capacity and high power density storage devices are also developed. The conversion efficiency of current state-of-the-art thermoelectric

Jeannine Robin Szczech

2010-01-01

397

Resonant high energy graviton to photon conversion at post recombination epoch  

E-print Network

Resonant conversion of high energy gravitons into photons in large scale cosmological magnetic fields at the post recombination epoch is considered. It is shown that the probability of the resonance photon production is much higher than the non-resonant one. As a result an observable isotropic background of cosmic gamma rays might be created. As shown in our previous paper, an early population of primordial black holes (PBHs) prior to big bang nucleosynthesis (BBN) could be an efficient source of high frequency gravitational waves. For the primordial black hole mass about $10^8$ g the produced photons would be the dominant component of the soft to hard Cosmic X-ray Background (CXB) and for lower masses the spectrum is shifted down to the ultraviolet and optic.

Alexander D. Dolgov; Damian Ejlli

2013-05-08

398

Decreasing geothermal energy conversion costs with advanced materials  

SciTech Connect

If the Geothermal Technology Division (GTD) is to meet its programmatic objectives in hydrothermal fluid production and energy conversion, it is essential that new materials of construction be available. Level III Program Objectives include (1) reducing the costs associated with lost circulation episodes by 30% by 1992, (2) reducing the costs of deep wells and directionally dried wells by 10% by 1992, (3) reducing well-cementing problems for typical hydrothermal wells by 20% by 1991, and (4) the development of a corrosion-resistant and low-fouling heat exchanger tube material costing no more than three times the cost of carbon steel tubes by 1991. The Brookhaven National Laboratory (BNL) materials program is focused on meeting these objectives. Currently, work is in progress on (1) high temperature chemical systems for lost circulation control, (2) advanced high temperature (300/sup 0/C), lightweight (approx. 1.1 g/cc), CO/sub 2/-resistant well cementing materials, (3) thermally conductive composites for heat exchanger tubing, and (4) ultra high temperature (600/sup 0/C) cements for magma wells. In addition, high temperature elastomer technology developed earlier in the program is being transferred for use in the Geothermal Drilling Organization programs on drill pipe protectors, rotating head seals, and blow-out preventors. Recent accomplishments and the current status of work in each subtask are summarized in the paper.

Kukacka, L.E.

1988-03-01

399

Photochemical conversion of solar energy in the environment. Book chapter  

SciTech Connect

Past research on photochemistry in the environment has focused on gas phase reactions in the atmosphere. Recently, however, environmentally significant photoreactions have been discovered in natural waters (i.e., the sea, lakes, and rivers), on soil surfaces, and in atmospheric condensed phases. These new investigations have been stimulated in part by interest in developing a scientific understanding of the role of photochemical processes in the biogeochemical cycles of various elements. In addition, other studies have explored the role of natural photochemical processes in cleansing the environemnt of various waste materials or, in some cases, in converting the wastes to more toxic substances. In the paper, current research results on the photochemical conversion of solar energy in aquatic environments and on soil and metal oxide surfaces are presented. Rate equations and products for selected homogeneous and heterogeneous photoreactions that occur in these systems are described. Data are presented for direct and sensitized photoreactions and for sunlight-initiated free radical reactions. (Copyright (c) 1991 Kluwer Academic Publishers.)

Zepp, R.G.

1991-01-01

400

Draft environmental assessment: Ocean Thermal Energy Conversion (OTEC) Pilot Plants  

SciTech Connect

This Environmental Assessment (EA) has been prepared, in accordance with the National Environmental Policy Act of 1969, for the deployment and operation of a commercial 40-Megawatt (MW) Ocean Thermal Energy Conversion (OTEC) Pilot Plant (hereafter called the Pilot Plant). A description of the proposed action is presented, and a generic environment typical of the candidate Pilot Plant siting regions is described. An assessment of the potential environmental impacts associated with the proposed action is given, and the risk of credible accidents and mitigating measures to reduce these risks are considered. The Federal and State plans and policies the proposed action will encompass are described. Alternatives to the proposed action are presented. Appendix A presents the navigation and environmental information contained in the US Coast Pilot for each of the candidate sites; Appendix B provides a brief description of the methods and calculations used in the EA. It is concluded that environmental disturbances associated with Pilot Plant activities could potentially cause significant environmental impacts; however, the magnitude of these potential impacts cannot presently be assessed, due to insufficient engineering and environmental information. A site- and design-specific OTEC Pilot Plant Environmental Impact Statement (EIS) is required to resolve the potentially significant environmental effects associated with Pilot Plant deployment and operation. (WHK)

Sullivan, S.M.; Sands, M.D.; Donat, J.R.; Jepsen, P.; Smookler, M.; Villa, J.F.

1981-02-01

401

Fluidized-bed energy technology for biomass conversion  

SciTech Connect

Fluidized-bed technology offers several unique features for use in small-scale biomass energy conversion. Results are reported in the use of a 61-cm fluidized-bed reactor for combustion and on the use of 61-, 30-, and 5-cm reactors for gasification. combustion trials using agricultural biomass feeds have identified several problem areas. Slagging and fouling can occur at bed temperatures as low as 760/sup 0/C. Moreover, metal coupons placed in the hot exhaust gas stream experienced high rates of corrosion and erosion. Gasification experiments have confirmed that a fluidized bed will accept a wide range of biomass feeds (rice hulls, corncobs, sorghum stalks, cottom gin trash) and convert them into a low-Btu combustible gas. Slagging and fouling were not as severe when operating the fluidized bed in the gasification mode. Gas cleanup requirements as well as technical needs in evaluating corrosion of reactor construction materials are identified. Coupling of the 61-cm reactor to a steam boiler is described. Finally, the nature of fluidized-bed technology suggests potentials for biomass pyrolysis, and such use is examined. 2 figures, 5 tables.

Soltes, E.J.; Lepori, W.A.; Pollock, T.C.

1982-01-01

402

Photovoltaic solar energy conversion in the '80s  

NASA Astrophysics Data System (ADS)

The potential for photovoltaic solar energy conversion in the generation of electricity to meet the needs of industrial and developing nations in the 1980s is discussed. The current technology of photovoltaic cells and modules, which are for the most part based on single crystal silicon and can deliver peak powers of 2 to 40 W at 6 to 12 V, is reviewed and prospects for cost reduction in the short- and medium-term by the development of new materials and production methods and increased cell efficiency and in the long term by the development of thin film cells, alternative compounds and mass production are indicated. Possible applications of photovoltaic-derived electricity are pointed out, including educational television receivers, rural telephones, refrigerators, water pumping and hospitals in developing nations and telecommunications, cathodic protection, signaling, telemetry and low-power pumping applications in industrial nations. Predictions of a photovoltaic peak Watt installed costing less than 10 francs by 1990 and a market above 100 MW in 1985 are pointed out.

Chevalier, I.

1981-04-01

403

Modeling and analysis of hybrid geothermal-solar thermal energy conversion systems  

E-print Network

Innovative solar-geothermal hybrid energy conversion systems were developed for low enthalpy geothermal resources augmented with solar energy. The goal is to find cost-effective hybrid power cycles that take advantage of ...

Greenhut, Andrew David

2010-01-01

404

A Review of Previous Research in Direct Energy Conversion Fission Reactors  

SciTech Connect

From the earliest days of power reactor development, direct energy conversion was an obvious choice to produce high efficiency electric power generation. Directly capturing the energy of the fission fragments produced during nuclear fission avoids the intermediate conversion to thermal energy and the efficiency limitations of classical thermodynamics. Efficiencies of more than 80% are possible, independent of operational temperature. Direct energy conversion fission reactors would possess a number of unique characteristics that would make them very attractive for commercial power generation. These reactors would be modular in design with integral power conversion and operate at low pressures and temperatures. They would operate at high efficiency and produce power well suited for long distance transmission. They would feature large safety margins and passively safe design. Ideally suited to production by advanced manufacturing techniques, direct energy conversion fission reactors could be produced more economically than conventional reactor designs. The history of direct energy conversion can be considered as dating back to 1913 when Moseleyl demonstrated that charged particle emission could be used to buildup a voltage. Soon after the successful operation of a nuclear reactor, E.P. Wigner suggested the use of fission fragments for direct energy conversion. Over a decade after Wigner's suggestion, the first theoretical treatment of the conversion of fission fragment kinetic energy into electrical potential appeared in the literature. Over the ten years that followed, a number of researchers investigated various aspects of fission fragment direct energy conversion. Experiments were performed that validated the basic physics of the concept, but a variety of technical challenges limited the efficiencies that were achieved. Most research in direct energy conversion ceased in the US by the late 1960s. Sporadic interest in the concept appears in the literature until this day, but there have been no recent significant programs to develop the technology.

DUONG,HENRY; POLANSKY,GARY F.; SANDERS,THOMAS L.; SIEGEL,MALCOLM D.

1999-09-22

405

A sequential simulation method for the generating capacity adequacy evaluation of small stand-alone wind energy conversion systems  

Microsoft Academic Search

This paper describes a sequential Monte Carlo simulation method for generating capacity adequacy evaluation of small stand-alone wind energy conversion systems containing battery storage. The wind speed, the energy conversion by the wind turbine generator, the equipment reliability and the energy storage facilities are major factors influencing the reliability performance of a wind energy conversion system. Time series models were

Roy Billinton; Bagen

2002-01-01

406

Hybridizing Energy Conversion and Storage in a Mechanical-to-Electrochemical Process for Self-Charging Power Cell  

E-print Network

Hybridizing Energy Conversion and Storage in a Mechanical-to- Electrochemical Process for Self-charging power cell, mechanical energy, piezoelectricity, lithium ion battery, electrochemistry Energy conversion physical units achieving the conversions from mechanical energy to electricity and then from electric

Wang, Zhong L.

407

Biomass conversion Task 4 1988 program of work: International Energy Agency Bioenergy Agreement  

SciTech Connect

For biomass to meet its potential as an energy resource, conversion processes must be available which are both efficient and environmentally acceptable. Conversion can include direct production of heat and electricity as well as production of intermediate gaseous, liquid, and solid fuels. While many biomass conversion processes are commercially available at present, others are still in the conceptual stage. Additional research and development activities on these advanced concepts will be necessary to fully use biomass resources. Ongoing research on biomass conversion processes is being conducted by many nations throughout the world. In an effort to coordinate this research and improve information exchange, several countries have agreed to a cooperative effort through the International Energy Agency's Bioenergy Agreement (IEA/BA). Under this Agreement, Task IV deals specifically with biomass conversion topics. The cooperative activities consists of information exchange and coordination of national research programs on specific topics. The activities address biomass conversion in a systematic manner, dealing with the pretreatment of biomass prior to conversion, the subsequent conversion of the biomass to intermediate fuels or end-product energy, and then the environmental aspects of the conversion process. This document provides an outline of cooperative work to be performed in 1988. 1 fig., 2 tabs.

Stevens, D.J.

1987-12-01

408

A twisted wire-shaped dual-function energy device for photoelectric conversion and electrochemical storage.  

PubMed

A wire-shaped energy device that can perform photoelectric conversion and electrochemical storage was developed through a simple but effective twisting process. The energy wire exhibited a high energy conversion efficiency of 6.58?% and specific capacitance of 85.03??F?cm(-1) or 2.13?mF?cm(-2), and the two functions were alternately realized without sacrificing either performance. PMID:24740877

Sun, Hao; You, Xiao; Deng, Jue; Chen, Xuli; Yang, Zhibin; Chen, Peining; Fang, Xin; Peng, Huisheng

2014-06-23

409

Unit Conversions  

NSDL National Science Digital Library

This resource is a digital tool for performing unit conversions. It provides the additional feature of displaying cancellation of terms, enabling users to gain a deeper understanding of the mathematical processes involved in converting units. Users can convert among 25 quantities, including units such as force, temperature, energy, and current. Also available are less commonly used units, such as illuminance and magnetic flux. In addition, the calculations respect the number of significant figures. It is part of Web-Based Computer Aided Instruction, a set of free resources for teachers and learners.

Taha Mzoughi

410

ON MICROSCALE ENERGY CONVERSION AND MECHANICAL POWER GENERATION THROUGH EXPLOSIVE VAPORIZATION FROM MICROHEATERS  

Microsoft Academic Search

The exponential growth of microelectrome-chanical systems (MEMS) in a variety of technological applications has provided impetus for the development of energy conversion methods directly related to the operation of these systems. It is often the case that this conversion should produce at the end mechanical work, as needed, for example, for the operation of micropumps, microactuators, microswitches and micro- valves,)

Dimos Poulikakos

411

Self-oscillating modulators for direct energy conversion audio power amplifiers  

E-print Network

Self-oscillating modulators for direct energy conversion audio power amplifiers Petar Ljusev1 conversion audio power amplifier represents total integration of switching-mode power supply and Class D audio power amplifier into one compact stage, achieving high efficiency, high level of integration, low

412

Biomass Conversion Task IV 1987 program of work: International Energy Agency Bioenergy Agreement  

SciTech Connect

Biomass is a major, renewable energy resource through out the world, and extensive research is being conducted by many countries on bioenergy technologies. In an effort to improve communications and cooperation in the area of biomass energy, several nations have agreed to a cooperative program of work under the International Energy Agency's Bioenergy Agreement (IEA/BA). Three areas of major importance have been identified including Short Rotation Forestry, Conventional Forestry, and Biomass Conversion. This document describes the 1987 Program of Work for cooperative activities in the area of Biomass Conversion. The background of the cooperation and descriptions of specific conversion projects are presented. Details of activity funding are also provided. 3 tabs.

Stevens, D.J.

1986-12-01

413

Energy conversion system optimization study for multimegawatt space nuclear power application  

NASA Astrophysics Data System (ADS)

An energy conversion system optimization study followed by an overall power system parametric analysis was performed in response to the multimegawatt power needs of some of the SDI missions during both alert and burst modes of operation. The study of the energy conversion system revealed that for the power ranges under consideration, the potassium Rankine cycle system is superior to the closed loop Brayton cycle system, but competitive with the open loop Brayton cycle system. In addition, it was verified through extensive computer simulations that the combined burst/alert mode radiator is indeed the most massive component of the energy conversion system and, in fact, of the overall power system.

Parlos, Alexander G.; El-Genk, Mohamed S.; McGhee, John M.; Buden, David; Mims, Jim

414

HIGH-VOLTAGE LOW POWER ANALOGUE-TO-DIGITAL CONVERSION FOR ADAPTIVE ARCHITECTURES OF CAPACITIVE VIBRATION ENERGY  

E-print Network

conversion of the vibration energy. This block is achieved with a successive approximation analogue to achieve optimal electromechanical conversion of the vibration energy. This control requires some (since Cres >> Cstore). Fig. 3 shows that the energy conversion is maximal for a particular range (U1, U2

Boyer, Edmond

415

LASER ENERGY CONVERSION TO SOLITONS AND MONOENERGETIC PROTONS IN NEAR-CRITICAL HYDROGEN PLASMA*  

E-print Network

heating by the laser pulse, it ultimately results in well- collimated, high-energy ion beamsLASER ENERGY CONVERSION TO SOLITONS AND MONOENERGETIC PROTONS IN NEAR-CRITICAL HYDROGEN PLASMA* I to find ways for better converting the laser beam energy to directed proton beams of a narrow energy

Brookhaven National Laboratory

416

Energy conversion efficiency of hybrid electric heavy-duty vehicles operating according to diverse drive cycles  

Microsoft Academic Search

Energy consumption and exhaust emissions of hybrid electric vehicles (HEVs) strongly depend on the HEV topology, power ratios of their components and applied control strategy. Combined analytical and simulation approach was applied to analyze energy conversion efficiency of different HEV topologies. Analytical approach is based on the energy balance equations and considers all energy paths in the HEVs from the

Titina Banjac; Ferdinand Trenc; Tomaž Katrašnik

2009-01-01

417

Mode conversion and absorption of fast waves at high ion cyclotron harmonics in inhomogeneous magnetic fields  

SciTech Connect

The propagation and absorption of high harmonic fast waves is of interest for non-inductive current drives in fusion experiments. The fast wave can be coupled with the ion Bernstein wave that propagates in the high magnetic field side of an ion cyclotron harmonic resonance layer. This coupling and the absorption are analyzed using the hot plasma dispersion relation and a wave equation that was converted from an approximate dispersion relation for the case where ?{sub i}=k{sub ?}{sup 2}?{sub i}{sup 2}/2?1 (where k{sub ?} is the perpendicular wave number and ?{sub i} is the ion Larmor radius). It is found that both reflection and conversion may occur near the harmonic resonance layer but that they decrease rapidly, giving rise to a sharp increase in the absorption as the parallel wave number increases.

Cho, Suwon, E-mail: swcho@kgu.ac.kr [Department of Physics, Kyonggi University, Suwon, Kyonggi-Do 443-760 (Korea, Republic of)] [Department of Physics, Kyonggi University, Suwon, Kyonggi-Do 443-760 (Korea, Republic of); Kwak, Jong-Gu [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of)] [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of)

2014-04-15

418

Frequency conversion in magnetoelectric composites for quasi-static magnetic field detection  

NASA Astrophysics Data System (ADS)

We present the detection of quasi-static magnetic fields in Metglas/piezofiber magnetoelectric (ME) composites through frequency conversion. The nonlinear coefficient over wide frequency range (1-30 kHz) was measured, and the noise behavior at sideband was also studied. It was found that the major part of the sideband noise originated from the driven current. Due to the characteristic of the driven current, the sideband noise increased with the increase of the frequency. The ME sensor exhibited excellent performance at low frequencies, sensitivities of 10 mHz, 100 mHz, and 1 Hz were 200 pT, 150 pT, and 20 pT, respectively.

Liu, Yuting; Jiao, Jie; Ma, Jiashuai; Ren, Bo; Li, Lingying; Zhao, Xiangyong; Luo, Haosu; Shi, Ling

2013-11-01

419

Development of an efficient and innovative sun engine for solar to electrical energy conversion  

SciTech Connect

How much of the energy of a renewable source like solar is it possible to convert into work, and what is the maximum efficiency that could be obtained from that system. A growing number of investigators around the world are working on the solution to introduce efficient renewable energy conversion systems beyond contemporary conventional energy conversion systems which then may bring a technological break through for solving the energy and environmental problems. Therefore, further work is being conducted to promote the development of efficient and innovative conversion systems in Mexico, based on the large amount of renewable energy available there. Based on the trends of renewable energy conversion for reduction of irreversibilities at the design phase of an efficient renewable energy conversion system and focusing the attention on frictionless and vacuum environments, an innovative and efficient system is introduced for conversion of solar energy to electric power at the maximum allowed by the second law of thermodynamics. The main idea of the present sun engine; MAG-solar-1, is to be capable to: absorb solar energy, with the use of an efficient solar concentrator; store that energy, in a frictionless rotor-flywheel located in a nearly vacuum environment; and deliver power generation, at high competitive levels of efficiency. The target of the above mentioned solar device, from the thermodynamic point of view, is be the most efficient system when it is compared with photovoltaic solar modules for electrical generation under the same energy radiation conditions. Based on a solar module proposed efficiency of 15% (under solar concentration), and an expected high efficiency motor/generator (no hysteresis effects) up to 95%, the MAG-solar-1 system shall be at least 15.8% efficient during the process of solar to electrical energy conversion; the challenge is to produce a physical prototype.

Orosco, E.V.

1998-07-01

420

Energy Distribution in Melvin's Magnetic Universe  

E-print Network

We use the energy-momentum complexes of Landau and Lifshitz and Papapetrou to obtain the energy distribution in Melvin's magnetic universe. For this space-time we find that these definitions of energy give the same and convincing results. The energy distribution obtained here is the same as we obtained earlier for the same space-time using the energy-momentum complex of Einstein. These results uphold the usefulness of the energy-momentum complexes.

S. S. Xulu

1999-12-22

421

Nanostructural engineering of vapor-processed organic photovoltaics for efficient solar energy conversion from any Surface  

E-print Network

More than two billion people in the world have little or no access to electricity. To be empowered they need robust and lightweightrenewable energy conversion technologies that can be easily transported with high yield ...

Macko, Jill Annette (Jill Annette Rowehl)

2014-01-01

422

Micro/Nano-Scale Phase Change Systems for Thermal Management and Solar Energy Conversion Applications  

E-print Network

phase change heat transfer is the driving mechanism of energy conversion and transport via boilers, turbines, and heat exchangers.heat exchangers,[15] etc. In all of these systems, effective phase change

Coso, Dusan

2013-01-01

423

Global energy conversion rate from geostrophic flows into internal lee waves in the deep ocean  

E-print Network

A global estimate of the energy conversion rate from geostrophic flows into internal lee waves in the ocean is presented. The estimate is based on a linear theory applied to bottom topography at O(1–10) km scales obtained ...

Nikurashin, Maxim

424

Recent developments in high-temperature photonic crystals for energy conversion  

E-print Network

After decades of intense studies focused on cryogenic and room temperature nanophotonics, scientific interest is also growing in high-temperature nanophotonics aimed at solid-state energy conversion. These latest extensive ...

Rinnerbauer, Veronika

425

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage  

E-print Network

Functional materials for energy conversion and storage exhibit strong coupling between electrochemistry and mechanics. For example, ceramics developed as electrodes for both solid oxide fuel cells and batteries exhibit ...

Swallow, Jessica Gabrielle

426

High figure of merit for electrokinetic energy conversion in Nafion membranes  

NASA Astrophysics Data System (ADS)

Based on measurements of the streaming potential coefficient, hydraulic permeability and ion conductivity the electrokinetic energy conversion of nanoporous ion conductive Nafion®117 polymer membrane has been evaluated. A high figure-of-merit of 1.1 ± 0.2 has been found in 0.03 M aqueous LiCl solution that corresponds to an electrokinetic energy conversion efficiency of approximately 18 ± 2%. To the best of our knowledge, this is the first study in the literature designated to the electrokinetic energy conversion in materials where the pores have high surface charge density. The initial results are promising with respect to future electrokinetic generator or pump applications and highly charged polymer membranes might be a future pathway for low-cost high-efficiency electrokinetic energy conversion.

Kilsgaard, Bjørn Sjøgren; Haldrup, Sofie; Catalano, Jacopo; Bentien, Anders

2014-02-01

427

Mode-conversion enhancement of guided optical waves by magnetostatic surface waves propagating collinearly in obliquely magnetized bismuth-doped yttrium-iron-garnet film waveguide  

Microsoft Academic Search

The dispersion formula and dynamic magnetization for magnetostatic surface waves (MSSWs) under arbitrarily inclined bias magnetic field and the mode-conversion effect of guided optical waves (GOWs) by the MSSWs propagating collinearly in obliquely magnetized bismuth-doped yttrium-iron-garnet film waveguide are studied theoretically. It is shown by our calculation that: (1) by optimizing the direction of bias magnetic field, the mode-conversion efficiency

Bao-Jian Wu; Feng Wen; Kun Qiu

2006-01-01

428

Broken Bar Detection in Synchronous Machines Based Wind Energy Conversion System  

E-print Network

BROKEN BAR DETECTION IN SYNCHRONOUS MACHINES BASED WIND ENERGY CONVERSION SYSTEM A Dissertation by MINA MASHHADI RAHIMIAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of DOCTOR OF PHILOSOPHY August 2011 Major Subject: Electrical Engineering BROKEN BAR DETECTION IN SYNCHRONOUS MACHINES BASED WIND ENERGY CONVERSION SYSTEM A Dissertation by MINA MASHHADI RAHIMIAN...

Rahimian, Mina Mashhadi

2012-10-19

429

Synthesis of Titanium Dioxide Hetero-Structures for Photovoltaic Energy Conversion  

E-print Network

SYNTHESIS OF TITANIUM DIOXIDE HETERO-STRUCTURES FOR PHOTOVOLTAIC ENERGY CONVERSION A Thesis by JONGBOK PARK Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 2009 Major Subject: Mechanical Engineering SYNTHESIS OF TITANIUM DIOXIDE HETERO-STRUCTURES FOR PHOTOVOLTAIC ENERGY CONVERSION A Thesis by JONGBOK PARK Submitted to the Office...

Park, Jongbok

2010-10-12

430

Thermophotovoltaic energy conversion system having a heavily doped n-type region  

DOEpatents

A thermophotovoltaic (TPV) energy conversion semiconductor device is provided which incorporates a heavily doped n-type region and which, as a consequence, has improved TPV conversion efficiency. The thermophotovoltaic energy conversion device includes an emitter layer having first and second opposed sides and a base layer in contact with the first side of the emitter layer. A highly doped n-type cap layer is formed on the second side of the emitter layer or, in another embodiment, a heavily doped n-type emitter layer takes the place of the cap layer.

DePoy, David M. (Clifton Park, NY); Charache, Greg W. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY)

2000-01-01

431

The Magnetic Free Energy in Active Regions  

NASA Technical Reports Server (NTRS)

The magnetic field permeating the solar atmosphere governs much of the structure, morphology, brightness, and dynamics observed on the Sun. The magnetic field, especially in active regions, is thought to provide the power for energetic events in the solar corona, such as solar flares and Coronal Mass Ejections (CME) and is believed to energize the hot coronal plasma seen in extreme ultraviolet or X-rays. The question remains what specific aspect of the magnetic flux governs the observed variability. To directly understand the role of the magnetic field in energizing the solar corona, it is necessary to measure the free magnetic energy available in active regions. The grant now expiring has demonstrated a new and valuable technique for observing the magnetic free energy in active regions as a function of time.

Metcalf, Thomas R.; Mickey, Donald L.; LaBonte, Barry J.

2001-01-01

432

Satellite power systems (SPS) energy conversion and power management  

SciTech Connect

Two reference systems are included in the NASA/DOE reference set - gallium arsenide (GaAs) and silicon (Si). Both the GaAs and Si photovoltaic concepts are coplanar and have a single microwave antenna located at the end of the satellite to provide 5 gigawatts (GW) of power at the utility interface. Impacts are reported that would result to the reference concept from these alternatives to microwave conversion, photovoltaic techniques, solar concentration ratio, and power distribution voltage. 3 refs.

Nussberger, A.A.

1981-01-01

433

Diminiode thermionic energy conversion with lanthanum-hexaboride electrodes  

NASA Technical Reports Server (NTRS)

Thermionic conversion data obtained from a variable gap cesium diminiode with a hot pressed, sintered lanthanum hexaboride emitter and an arc melted lanthanum hexaboride collector are presented. Performance curves cover a range of temperatures: emitter 1500 to 1700 K, collector 750 to 1000 K, and cesium reservoir 370 to 510 K. Calculated values of emitter and collector work functions and barrier index are also given.

Kroeger, E. W.; Bair, V. L.; Morris, J. F.

1978-01-01

434

Control Strategies for Smoothing of Output Power of Wind Energy Conversion Systems  

NASA Astrophysics Data System (ADS)

This article presents a control method for output power smoothing of a wind energy conversion system (WECS) with a permanent magnet synchronous generator (PMSG) using the inertia of wind turbine and the pitch control. The WECS used in this article adopts an AC-DC-AC converter system. The generator-side converter controls the torque of the PMSG, while the grid-side inverter controls the DC-link and grid voltages. For the generator-side converter, the torque command is determined by using the fuzzy logic. The inputs of the fuzzy logic are the operating point of the rotational speed of the PMSG and the difference between the wind turbine torque and the generator torque. By means of the proposed method, the generator torque is smoothed, and the kinetic energy stored by the inertia of the wind turbine can be utilized to smooth the output power fluctuations of the PMSG. In addition, the wind turbines shaft stress is mitigated compared to a conventional maximum power point tracking control. Effectiveness of the proposed method is verified by the numerical simulations.

Pratap, Alok; Urasaki, Naomitsu; Senju, Tomonobu

2013-10-01

435

Electrofluid dynamics energy conversion research. Final report 18 mar 73-30 jun 75  

Microsoft Academic Search

Electrofluid Dynamics (EFD) is a method of direct energy conversion in which the energy contained in a flowing gas is converted directly into electrical energy. This is generally accomplished by seeding the flowing gas with unipolar charged ions produced by a corona discharge from a sharp grounded electrode. The unipolar ions typically are deposited on particles usually produced by condensation

E. F. Fretter; R. W. Griffith

1975-01-01

436

Design and Performance of Linear Biomechanical Energy Conversion Devices Penglin Niu, Student Member  

E-print Network

such as mobile phones, digital assistants, wireless internet devices, music players, and so forth increase Abstract--This paper addresses three human motions and devices for potential energy harvesting. Arm swing, energy conversion, synchronous rectifier, voltage tripler, energy harvesting, human power. I

Chapman, Patrick

437

Abstract--This paper addresses the problem of controlling wind energy conversion systems (WECS) which involve  

E-print Network

Abstract-- This paper addresses the problem of controlling wind energy conversion systems (WECS-inverter. The goal of control is to maximize wind energy extraction and this needs letting the wind turbine rotor wind energy extraction) only for one wind speed value depending on the considered value of turbine

Paris-Sud XI, Université de

438

Graphene-based photovoltaic cells for near-field thermal energy conversion  

E-print Network

Graphene-based photovoltaic cells for near-field thermal energy conversion Riccardo Messina surface, at distances smaller than the thermal wavelength lth 5 c/ (kBT), the electromagnetic energy important source of energy. By approaching a photovoltaic (PV) cell3 in proximity of a thermal emitter

Paris-Sud XI, Université de

439

Nanomaterials of silicides and silicon for energy conversion and storage  

NASA Astrophysics Data System (ADS)

Our consumption of fossil fuels can be reduced to address the pressing concerns of global climate change by maximizing the efficiency of conversion technologies. Since many of the alternative fuel sources also being examined are intermittent in nature, it is imperative that high capacity and high power density storage devices are also developed. The conversion efficiency of current state-of-the-art thermoelectric materials is too low to meet our needs, but it may be possible to increase the conversion efficiency of thermoelectric materials by moving from the bulk to the nanoscale. The transition metal silicides, including CrSi2, beta-FeSi2 , Mg2Si and MnSi1.7, have been explored as environmentally friendly non-toxic thermoelectric materials. I began my research in the group synthesizing silicide nanowires via chemical vapor transport (CVT), and later expanded my research to include the synthesis of silicide nanocomposites for thermoelectrics and mesoporous silicon nanocomposites for use as high capacity lithium battery electrodes. Nanoscale thermoelectrics and the enhanced thermoelectric figure-of-merit ZT reported by thermoelectric researchers are reviewed in Chapter 1. Chapter 2 reviews the progress being made in the research community with nanoscale and nanostructured silicon battery anodes. The synthesis and characterization of CrSi2 nanowires synthesized via CVT is detailed in Chapter 3, followed by hyperbranched epitaxial FeSi nanostructures exhibiting merohedral twinning in Chapter 4. Nanowires are fundamentally interesting and provide insight into the changes in materials properties compared to the bulk. The synthesis of interesting nanostructured silicide materials are detailed in Chapter 5, where the conversion of diatoms into a nanostructured thermoelectric Mg2Si/MgO nanocomposite that retains the basic diatom structure after conversion is detailed. This reaction was then modified to use mesoporous silica instead of diatoms to reduce the nanocrystalline domain size and to synthesize mesoporous silicon/carbon nanocomposites for use as lithium battery anodes. This nanocomposite is presented in Chapter 6, with details of its preliminary electrochemical performance. Chapter 7 details the synthesis of mesoporous Si1-xGe xO2, which has previously been reported only once in the literature.

Szczech, Jeannine Robin

440

Magnetic induction systems to harvest energy from mechanical vibrations  

E-print Network

This thesis documents the design process for magnetic induction systems to harvest energy from mechanical vibrations. Two styles of magnetic induction systems - magnet-through-coil and magnet-across-coils - were analyzed. ...

Jonnalagadda, Aparna S

2007-01-01

441

Solar energy conversion via hot electron internal photoemission in metallic nanostructures: Efficiency estimates  

SciTech Connect

Collection of hot electrons generated by the efficient absorption of light in metallic nanostructures, in contact with semiconductor substrates can provide a basis for the construction of solar energy-conversion devices. Herein, we evaluate theoretically the energy-conversion efficiency of systems that rely on internal photoemission processes at metal-semiconductor Schottky-barrier diodes. In this theory, the current-voltage characteristics are given by the internal photoemission yield as well as by the thermionic dark current over a varied-energy barrier height. The Fowler model, in all cases, predicts solar energy-conversion efficiencies of <1% for such systems. However, relaxation of the assumptions regarding constraints on the escape cone and momentum conservation at the interface yields solar energy-conversion efficiencies as high as 1%–10%, under some assumed (albeit optimistic) operating conditions. Under these conditions, the energy-conversion efficiency is mainly limited by the thermionic dark current, the distribution of hot electron energies, and hot-electron momentum considerations.

Leenheer, Andrew J.; Narang, Prineha; Atwater, Harry A., E-mail: haa@caltech.edu [Thomas J. Watson Laboratories of Applied Physics, California Institute of Technology, Pasadena, California 91125 (United States); Joint Center for Artificial Photosynthesis, Pasadena, California 91125 (United States); Lewis, Nathan S. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States); Joint Center for Artificial Photosynthesis, Pasadena, California 91125 (United States)

2014-04-07

442

Solvent conversion in refinery treating system results in energy savings  

SciTech Connect

GAS/SPEC SS Selective Solvent was first used in the amine section of GFU 244 at the Chevron (Port Arthur, Texas) Refinery during 1985 as a replacement for DEA (Diethanolamine). Since converting to GAS/SPEC SS Selective Solvent, the process parameters have been monitored closely to evaluate changes in utility requirements, solvent circulation rates and operating costs. Current operating conditions and annual operating costs were compared to the performance of DEA preceding the May, 1985 conversion. The results are summarized in this paper.

Cox, S.; Henry, T.; McDougal, K.; Daughtry, J.

1987-01-01

443

Inter-machine comparison of the termination phase and energy conversion in tokamak disruptions with runaway current plateau formation and implications for ITER  

NASA Astrophysics Data System (ADS)

The termination of the current and the loss of runaway electrons following runaway current plateau formation during disruptions have been investigated in the JET, DIII-D and FTU tokamaks. Substantial conversion of magnetic energy into runaway kinetic energy, up to ?10 times the initial plateau runaway kinetic energy, has been inferred for the slowest current terminations. Both modelling and experiment suggest that, in present devices, the efficiency of conversion into runaway kinetic energy is determined to a great extent by the characteristic runaway loss time, ?diff, and the resistive time of the residual ohmic plasma after the disruption, ?res, increasing with the ratio ?diff/?res. It is predicted that, in large future devices such as ITER, the generation of runaways by the avalanche mechanism will play an important role, particularly for slow runaway discharge terminations, increasing substantially the amount of energy deposited by the runaways onto the plasma-facing components by the conversion of magnetic energy of the runaway plasma into runaway kinetic energy. Estimates of the power fluxes on the beryllium plasma-facing components during runaway termination in ITER indicate that for runaway currents of up to 2 MA no melting of the components is expected. For larger runaway currents, minimization of the effects of runaway impact on the first wall requires a reduction in the kinetic energy of the runaway beam before termination and, in addition, high plasma density ne and low ohmic plasma resistance (long ?res) to prevent large conversion of magnetic into runaway kinetic energy during slow current terminations.

Martín-Solís, J. R.; Loarte, A.; Hollmann, E. M.; Esposito, B.; Riccardo, V.; FTU; DIII-D Teams; EFDA Contributors, JET

2014-08-01

444

Effect of biomass feedstock chemical and physical properties on energy conversion processes: Volume 2, Appendices  

SciTech Connect

This report presents an exploration of the relationships between biomass feedstocks and the conversion processes that utilize them. Specifically, it discusses the effect of the physical and chemical structure of biomass on conversion yields, rates, and efficiencies in a wide variety of available or experimental conversion processes. A greater understanding of the complex relationships between these conversion systems and the production of biomass for energy uses is required to help optimize the complex network of biomass production, collection, transportation, and conversion to useful energy products. The review of the literature confirmed the scarcity of research aimed specifically at identifying the effect of feedstock properties on conversion. In most cases, any mention of feedstock-related effects was limited to a few brief remarks (usually in qualitative terms) in the conclusions, or as a topic for further research. Attempts to determine the importance of feedstock parameters from published data were further hampered by the lack of consistent feedstock characterization and the difficulty of comparing results between different experimental systems. Further research will be required to establish quantitative relationships between feedstocks and performance criteria in conversion. 127 refs., 4 figs., 7 tabs.

Butner, R.S.; Elliott, D.C.; Sealock, L.J., Jr.; Pyne, J.W.

1988-12-01

445

CESIUM PLASMA STUDIES FOR THERMIONIC ENERGY CONVERSION. Final Report  

Microsoft Academic Search

A new method for measuring the volume recombination coefficient a of ; thermal cesium plasmas in steady state has been devised and perfected. In this ; method, a thermal cesium plasma column is magnetically confined between two ; plasma generators. The plasma is generatcd by contact ionization and thermionic ; emission. The rate of plasma generation is controlled by the

R. C. Knechtli; J. Y. Wada

1962-01-01

446

Direct conversion of infrared radiant energy for space power applications  

NASA Technical Reports Server (NTRS)

A proposed technology to convert the earth radiant energy (infrared albedo) for spacecraft power is presented. The resultant system would eliminate energy storage requirements and simplify the spacecraft design. The design and performance of a infrared rectenna is discussed.

Finke, R. C.

1982-01-01

447

Bio-inspired constructs for solar energy conversion  

Microsoft Academic Search

Solar energy input to the biosphere is about 10^24 joules\\/year. This makes human needs of even a projected 10^21 joules\\/year a deceptively achievable goal. One key to global-scale use of solar energy is the synthesis of energy-rich fuel materials such as hydrogen and reduced carbon compounds. The latter have the almost inestimable advantage that the energy infrastructure for distribution and

Thomas Moore

2006-01-01

448

Thermodynamic Inefficiency of Conversion of Solar Energy to Work.  

ERIC Educational Resources Information Center

Considers the thermodynamic limitation to the efficiency with which light energy can be converted into work, indicating that no single chemical system converting solar energy into useful work can be very efficient. Also indicates that if solar energy is absorbed as heat for heating purposes, it is almost completely used. (JN)

Adamson, Arthur W.; And Others

1984-01-01

449

The wells air turbine for wave energy conversion  

Microsoft Academic Search

The wave energy devices currently in operation in the United Kingdom and India and those that are to be built in Europe are based on the principle of the oscillating water-air column. In these devices the pneumatic energy of the oscillating air column is converted to mechanical energy of rotation by a Wells turbine. A monoplane (single plane) Wells turbine

S. Raghunathan

1995-01-01

450

A DSP control system for the grid-connected inverter in wind energy conversion system  

Microsoft Academic Search

The development of power electronics leads to the idea of variable-speed direct-drive generators in the field of wind energy conversion system. This paper discusses the PWM converter used as the grid-connected inverter in the variable-speed direct-drive conversion system. The grid-connected inverter has to be controlled to maintain constant DC link voltage and to keep sinusoidal AC current at unity power

Yang Zhenkun; Liang Hui; Sun Chuanyang

2005-01-01

451

High efficiency thermal to electric energy conversion using selective emitters and spectrally tuned solar cells  

NASA Technical Reports Server (NTRS)

Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1500 K. Depending on the nature of parasitic losses, overall thermal-to-electric conversion efficiencies greater than 20 percent are feasible.

Chubb, Donald L.; Flood, Dennis J.; Lowe, Roland A.

1992-01-01

452

Novel maximum-power-point-tracking controller for photovoltaic energy conversion system  

Microsoft Academic Search

A novel maximum-power-point-tracking (MPPT) controller for a photovoltaic (PV) energy conversion system is presented. Using the slope of power versus voltage of a PV array, the proposed MPPT controller allows the conversion system to track the maximum power point very rapidly. As opposed to conventional two-stage designs, a single-stage configuration is implemented, resulting in size and weight reduction and increased

Yeong-Chau Kuo; Tsorng-Juu Liang; Jiann-Fuh Chen

2001-01-01

453

MAGNETIC ENERGY PRODUCTION BY TURBULENCE IN BINARY NEUTRON STAR MERGERS  

SciTech Connect

The simultaneous detection of electromagnetic and gravitational wave emission from merging neutron star binaries would greatly aid in their discovery and interpretation. By studying turbulent amplification of magnetic fields in local high-resolution simulations of neutron star merger conditions, we demonstrate that magnetar-level ({approx}> 10{sup 16} G) fields are present throughout the merger duration. We find that the small-scale turbulent dynamo converts 60% of the randomized kinetic energy into magnetic fields on a merger timescale. Since turbulent magnetic energy dissipates through reconnection events that accelerate relativistic electrons, turbulence may facilitate the conversion of orbital kinetic energy into radiation. If 10{sup -4} of the {approx}10{sup 53} erg of orbital kinetic available gets processed through reconnection and creates radiation in the 15-150 keV band, then the fluence at 200 Mpc would be 10{sup -7} erg cm{sup -2}, potentially rendering most merging neutron stars in the advanced LIGO and Virgo detection volumes detectable by Swift BAT.

Zrake, Jonathan; MacFadyen, Andrew I. [Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003 (United States)

2013-06-01

454

A universal electromagnetic energy conversion adapter based on a metamaterial absorber.  

PubMed

On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor. PMID:25200005

Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D; Simons, Rainee N; Chen, Yunpeng; Xiao, John Q

2014-01-01

455

A universal electromagnetic energy conversion adapter based on a metamaterial absorber  

NASA Astrophysics Data System (ADS)

On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor.

Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D.; Simons, Rainee N.; Chen, Yunpeng; Xiao, John Q.

2014-09-01

456

A universal electromagnetic energy conversion adapter based on a metamaterial absorber  

PubMed Central

On the heels of metamaterial absorbers (MAs) which produce near perfect electromagnetic (EM) absorption and emission, we propose a universal electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the appropriate energy converting sensors, the UEECA is able to achieve near 100% signal transfer ratio between EM energy and various forms of energy such as thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength dimension and the EM field intensity enhancement can further empower UEECA in many critical applications such as energy harvesting, photoconductive antennas, and nonlinear optics. The principle of UEECA is understood with a transmission line model, which further provides a design strategy that can incorporate a variety of energy conversion devices. The concept is experimentally validated at a microwave frequency with a signal transfer ratio of 96% by choosing an RF diode as the energy converting sensor. PMID:25200005

Xie, Yunsong; Fan, Xin; Wilson, Jeffrey D.; Simons, Rainee N.; Chen, Yunpeng; Xiao, John Q.

2014-01-01

457

High electrokinetic energy conversion efficiency in charged nanoporous nitrocellulose/sulfonated polystyrene membranes.  

PubMed

The synthesis, characterization, and electrokinetic energy conversion performance have been investigated experimentally in a charged polymeric membrane based on a blend of nitrocellulose and sulfonated polystyrene. The membrane is characterized by a moderate ion exchange capacity and a relatively porous structure with average pore diameter of 11 nm. With electrokinetic energy conversion, pressure can be converted directly into electric energy and vice versa. From the electrokinetic transport properties, a remarkably large intrinsic maximum efficiency of 46% is found. It is anticipated that the results are an experimental verification of theoretical models that predict high electrokinetic energy conversion efficiency in pores with high permselectivity and hydrodynamic slip flow. Furthermore, the result is a promising step for obtaining efficient low-cost electrokinetic generators and pumps for small or microscale applications. PMID:25555128

Haldrup, Sofie; Catalano, Jacopo; Hansen, Michael Ryan; Wagner, Manfred; Jensen, Grethe Vestergaard; Pedersen, Jan Skov; Bentien, Anders

2015-02-11

458

Energy-yield and conversion-efficiency measurements of high-order harmonic radiation  

SciTech Connect

Experimental measurements of the absolute energy yields and conversion efficiencies of high-order harmonic radiation in the spectral range of 31 to 17 nm are presented. We examine energy yields as a function of a number of parameters including drive laser wavelength, target atom, focal geometry, and peak laser intensity, and we have generated individual harmonics with energies as high as 60 nJ at wavelengths as short as 20 nm. Under optimum conditions, we find that conversion efficiencies of as high as 10[sup [minus]7] into each harmonic are possible.

Ditmire, T.; Crane, J.K.; Nguyen, H.; DaSilva, L.B.; Perry, M.D. (Laser Program, Lawrence Livermore National Laboratory, L-443, P.O. Box 808 Livermore, California 94550 (United States))

1995-02-01

459

Vibration-to-electric energy conversion using a mechanically-varied capacitor  

E-print Network

Past research in vibration energy harvesting has focused on the use of variable capacitors, magnets, or piezoelectric materials as the basis of energy transduction. How- ever, few of these studies have explored the detailed ...

Yen, Bernard Chih-Hsun, 1981-

2005-01-01

460

Ocean thermal energy conversion plants: experimental and analytical study of mixing and recirculation  

Microsoft Academic Search

Ocean thermal energy conversion (OTEC) is a method of generating power using the vertical temperature gradient of the tropical ocean as an energy source. Experimental and analytical studies have been carried out to determine the characteristics of the temperature and velocity fields induced in the surrounding ocean by the operation of an OTEC plant. The condition of recirculation, i.e., the

G. H. Jirka; R. P. Johnson; D. J. Fry; D. R. F. Harleman

1977-01-01

461

Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire-array  

E-print Network

with non- aqueous electrolytes. These anodes exhibited overall inherent photoelectrode energy, and will aid in the design and optimization of nanowire-based systems for solar energy-conversion applications, the resistance losses of electrolytes, and any overpotentials that are required to drive water splitting

Zhou, Chongwu

462

Probabilistic performance assessment of autonomous solar-wind energy conversion systems  

Microsoft Academic Search

This paper describes the development of a general probabilistic model of an autonomous solar-wind energy conversion system (SWECS) composed of several wind turbines (wind farm), several photovoltaic (PV) modules (solar park), and a battery storage feeding a load. The model takes into consideration outages due to the primary energy fluctuations and hardware failure. It allows the simulation of wind farms

S. H. Karaki; R. B. Chedid; R. Ramadan

1999-01-01

463

Sep 05:"Toward Computational Design of Iron-Based Chromophores for Solar Energy Conversion"  

E-print Network

Sep 05:"Toward Computational Design of Iron-Based Chromophores for Solar Energy Conversion, Department of Biochemistry, East Carolina University (Dept) Nov 21: "Taking snapshots along the solar energy and Organic-Metal Halide Perovskites for Next Generation Solar Cells" Professor Prashant Kamat, Department

Reid, Scott A.

464

Compressed natural gas and liquefied petroleum gas conversions: The National Renewable Energy Laboratory`s experience  

Microsoft Academic Search

The National Renewable Energy Laboratory (NREL) contracted with conversion companies in six states to convert approximately 900 light-duty Federal fleet vehicles to operate on compressed natural gas (CNG) or liquefied petroleum gas (LPG). The contracts were initiated in order to help the Federal government meet the vehicle acquisition requirements of the Energy Policy Act of 1992 (EPACT) during a period

R. C. Motta; K. J. Kelly; W. W. Warnock

1996-01-01

465

Analysis of thermoelectric energy conversion efficiency with linear and nonlinear temperature dependence in material properties  

Microsoft Academic Search

A novel approach to estimate energy conversion efficiency for a power-generating thermoelectric element, whose material properties possess both linear (first order) and nonlinear (second order) dependence on temperature, is developed by solving the differential equation governing its temperature distribution, which includes both the Joule heat and the Thomson effect. In order to obtain analytic expressions for power output and energy

Daehyun Wee

2011-01-01

466

A variable speed wind energy conversion scheme for connection to weak AC systems  

Microsoft Academic Search

A three level control system for a variable speed wind energy conversion scheme (VSWECS) supplying a weak AC power system is presented. The objective of the control strategy is to maximize energy capture and simultaneously to support the voltage of the bus where the VSWECS is connected. Using an insulated gate bipolar transistor (IGBT) inverter, both control of active and

A. S. Neris; N. A. Vovos; G. B. Giannakopoulos

1999-01-01

467

Power strategies for maximum control structure of a wind energy conversion system with a synchronous machine  

Microsoft Academic Search

The control of a wind energy conversion system can be decomposed into two parts: a local control depending on the power structure and a global control (strategy) deduced from global considerations. The local part ensures an efficient energy management of each component of the system. The local control structure can be deduced from the Energetic Macroscopic Representation, which is a

A. Bouscayrol; Ph. Delarue; X. Guillaud

2005-01-01

468

Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses  

ERIC Educational Resources Information Center

Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching…

Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.

2013-01-01

469

Primordial Magnetic Fields from Dark Energy  

E-print Network

Evidences indicate that the dark energy constitutes about two thirds of the critical density of the universe. If the dark energy is an evolving pseudo scalar field that couples to electromagnetism, a cosmic magnetic seed field can be produced via spinoidal instability during the formation of large-scale structures.

Da-Shin Lee; Wolung Lee; Kin-Wang Ng

2002-08-30

470

Efficient conversion of solar energy to biomass and electricity  

PubMed Central

The Earth receives around 1000 W.m?2 of power from the Sun and only a fraction of this light energy is able to be converted to biomass (chemical energy) via the process of photosynthesis. Out of all photosynthetic organisms, microalgae, due to their fast growth rates and their ability to grow on non-arable land using saline water, have been identified as potential source of raw material for chemical energy production. Electrical energy can also be produced from this same solar resource via the use of photovoltaic modules. In this work we propose a novel method of combining both of these energy production processes to make full utilisation of the solar spectrum and increase the productivity of light-limited microalgae systems. These two methods of energy production would appear to compete for use of the same energy resource (sunlight) to produce either chemical or electrical energy. However, some groups of microalgae (i.e. Chlorophyta) only require the blue and red portions of the spectrum whereas photovoltaic devices can absorb strongly over the full range of visible light. This suggests that a combination of the two energy production systems would allow for a full utilization of the solar spectrum allowing both the production of chemical and electrical energy from the one facility making efficient use of available land and solar energy. In this work we propose to introduce a filter above the algae culture to modify the spectrum of light received by the algae and redirect parts of the spectrum to generate electricity. The electrical energy generated by this approach can then be directed to running ancillary systems or producing extra illumination for the growth of microalgae. We have modelled an approach whereby the productivity of light-limited microalgae systems can be improved by at least 4% through using an LED array to increase the total amount of illumination on the microalgae culture. PMID:24976951

2014-01-01

471

POSSIBILITIES OF DIRECT ENERGY CONVERSION FROM FUSION REACTORS  

Microsoft Academic Search

A method is suggested for extracting electrical energy directly from ; fusion reactors, and it is shown that about one-third of the available energy may ; be so extracted. In a power reactor, modulated currents of at least 8 ma are ; required with optimum fuel, purity and other conditions. (auth);

J. D. Jukes

1959-01-01

472

Efficiency of energy conversion for devices containing a piezoelectric component  

Microsoft Academic Search

Recent developments in miniaturized sensors, digital processors and wireless communication systems have many desirable applications. The realization of these applications however, is limited by the lack of a similarly sized power source. Micro-scale concepts to generate electrical power include devices which use the stored energy in fuels to those which harvest energy from the environment. Many proposed power generation systems

Cecilia D Richards; Michael J Anderson; David F Bahr; Robert F Richards

2004-01-01

473

Performance of bistable piezoelectric cantilever vibration energy harvesters with an elastic support external magnet  

NASA Astrophysics Data System (ADS)

Based on the research results of conventional rigid support nonlinear energy harvesters, in this paper we conceive a kind of structure with an elastic support external magnet with the intent to keep the system in the state of bistable oscillation, even under low-intensity excitation conditions. It has been proved that elastic support systems have better power output performance than rigid support systems when excited at low-intensity vibrations. In addition, elastic support nonlinear energy harvesters do not need real-time adjustment of the magnet interval towards the variable-intensity random excitation source, consequently achieving maximum power output and sufficient electromechanical energy conversion of the system.

Gao, Y. J.; Leng, Y. G.; Fan, S. B.; Lai, Z. H.

2014-09-01

474

Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy conversion subsystems and components. Part 3: Gasification, process fuels, and balance of plant  

NASA Technical Reports Server (NTRS)

Results are presented of an investigation of gasification and clean fuels from coal. Factors discussed include: coal and coal transportation costs; clean liquid and gas fuel process efficiencies and costs; and cost, performance, and environmental intrusion elements of the integrated low-Btu coal gasification system. Cost estimates for the balance-of-plant requirements associated with advanced energy conversion systems utilizing coal or coal-derived fuels are included.

Boothe, W. A.; Corman, J. C.; Johnson, G. G.; Cassel, T. A. V.

1976-01-01

475

Rankine cycle condenser pressure control using an energy conversion device bypass valve  

DOEpatents

The disclosure provides a waste heat recovery system and method in which pressure in a Rankine cycle (RC) system of the WHR system is regulated by diverting working fluid from entering an inlet of an energy conversion device of the RC system. In the system, an inlet of a controllable bypass valve is fluidly coupled to a working fluid path upstream of an energy conversion device of the RC system, and an outlet of the bypass valve is fluidly coupled to the working fluid path upstream of the condenser of the RC system such that working fluid passing through the bypass valve bypasses the energy conversion device and increases the pressure in a condenser. A controller determines the temperature and pressure of the working fluid and controls the bypass valve to regulate pressure in the condenser.

Ernst, Timothy C; Nelson, Christopher R; Zigan, James A

2014-04-01

476

Influence of second-order corrections to the energy-dependence of neutrino flavor conversion formulae  

E-print Network

We discuss the {\\em intermediate} wave-packet formalism for analytically quantifying the energy dependence of the two-flavor conversion formula that is usually considered for analyzing neutrino oscillations and adjusting the focusing horn, target position and/or detector location of some flavor conversion experiments. Following a sequence of analytical approximations where we consider the second-order corrections in a power series expansion of the energy, we point out a {\\em residual} time-dependent phase which, in addition to some well known wave-packet effects, can subtly modify the oscillation parameters and limits. In the present precision era of neutrino oscillation experiments where higher precision measurements are required, we quantify some small corrections in neutrino flavor conversion formulae which lead to a modified energy-dependence for $\

Alex E. Bernardini; Marcelo M. Guzzo

2007-11-29

477

Bio-inspired constructs for solar energy conversion  

NASA Astrophysics Data System (ADS)

Solar energy input to the biosphere is about 10^24 joules/year. This makes human needs of even a projected 10^21 joules/year a deceptively achievable goal. One key to global-scale use of solar energy is the synthesis of energy-rich fuel materials such as hydrogen and reduced carbon compounds. The latter have the almost inestimable advantage that the energy infrastructure for distribution and use is in place. The photosynthetic and respiratory enzymes provide paradigms for all of the important energy converting processes humans would need to achieve sustainable energy production and use. These include water oxidation, O2 reduction and oxidation of energy dense organics at room temperature. These processes are carried out by biological catalysts at near thermodynamic efficiency without the use of precious metals. Copper, manganese, iron and nickel are typically used at their active sites. Energy rich organics such as ethanol and larger reduced-carbon compounds offer energy densities comparable to that of fossil fuels yet technology has not produced a low temperature catalyst for breaking carbon-carbon bonds. Biology offers myriad examples of such catalysts. Electroreductive synthesis of organics from CO2 is also templated by Nature's catalysts. The challenge is clear: we must understand the structures and chemical reactivity of these catalytic sites and co-opt their essential features for human use. A number of parameters are involved and will be discussed. Even considering an artificial catalysts comprising only the atoms necessary for catalysis, the footprint is relatively large and, since biological turnover rates are often low, achieving current flows adequate for human needs in industry and transportation is problematic. A detailed understanding of efficiently coupling electromotive force to the active sites of redox enzymes will be one key to designing efficient hybrid catalytic devices. A model system for solar-driven reforming of biomass to H2 will be presented.

Moore, Thomas

2006-03-01

478

Feasibility assessment of low temperature voltaic energy conversion  

SciTech Connect

An experimental and theoretical investigation of the feasibility of thermo voltaic (TV) power generation in the temperature range 800{degrees}C - 1000{degrees}C has been performed. In this concept, voltaic cells of Indium-Galium-Arsenide (InGaAs) were employed to convert thermal radiation directly into electric power. The advantage of this concept over previous thermo photo voltaic concepts (TPV) is the reduced materials issues associated with a lower heat source temperature, and applicability to a wider range of fossil fuels. A numerical model was constructed and used to analyze test data, demonstrating good agreement and understanding of process physics. The key functional parameters were found to be dark current coefficient and spectral efficiency. A conversion efficiency of 25% was measured at 900{degrees}C, with potential for 30% in optimized devices. The limiting issue for a practical TV power converter below 900{degrees}C is the required power density, which is a strong function of heat source temperature.

Baldasaro, P.F.; Campbell, B.C.; Depoy, D.M.; Parrington, J.

1994-04-01

479

Assessment of dynamic energy conversion systems for radioisotope heat sources  

SciTech Connect

The use of dynamic conversion systems to convert the heat generated in a 7500 W(t) 90 Sr radioisotopic heat source to electricity is examined. The systems studies were Stirling; Brayton Cycle; three organic Rankines (ORCs) (Barber-Nichols/ORMAT, Sundstrand, and TRW); and an organic Rankine plus thermoelectrics. The systems were ranked for a North Warning System mission using a Los Alamos Multiattribute Decision Theory code. Three different heat source designs were used: case I with a beginning of life (BOL) source temperature of 640 C, case II with a BOL source temperature of 745/sup 0/C, and case III with a BOL source temperature of 945/sup 0/C. The Stirling engine system was the top-ranked system of cases I and II, closely followed by the ORC systems in case I and ORC plus thermoelectrics in case II. The Brayton cycle system was top-ranked for case III, with the Stirling engine system a close second. The use of /sup 238/Pu in heat source sizes of 7500 W(t) was examined and found to be questionable because of cost and material availability and because of additional requirements for analysis of safeguards and critical mass.

Thayer, G.R.; Mangeng, C.A.

1985-06-01

480

Relativistic fireballs - Energy conversion and time-scales  

NASA Technical Reports Server (NTRS)

The expansion energy of a relativistic fireball can be reconverted into radiation when it interacts with an external medium. For expansion with Lorentz factors greater than or approximately equal to 1000 into a typical galactic environment, the corresponding time-scale in the frame of the observer is of the order of seconds. This mechanism would operate in any cosmological scenario of gamma-ray bursts involving initial energies of order a percent of a stellar rest mass, and implies photon energies and time-scales compatible with those observed in gamma-ray bursts.

Rees, M. J.; Meszaros, P.

1992-01-01

481

Measurement of magnetic fluctuation induced energy transport  

SciTech Connect

The local electron energy flux produced by magnetic fluctuations has been measured directly in the MST reversed field pinch (over the radial range r/a > 0.75). The flux, produced by electrons traveling parallel to a fluctuating magnetic field, is obtained from correlation between the fluctuations in the parallel heat flux and the radial magnetic field. The fluctuation induced flux is large (100 kW/cm{sup 2}) in the ``core`` (r/a < 0.85) and small (< 10--30 kW/cm{sup 2}) in the edge.

Fiksel, G.; Prager, S.C.; Shen, W.; Stoneking, M.

1993-11-01

482

Wireless Sensor Network Energy Conversation Nathan A. Menhorn  

E-print Network

, Facilities, Buildings, and Homes - industrial automation - manufacturing and process control - heating, ventilation, and air conditioning control for energy sav- ings · Transportation Systems and Vehicles - smart . . . . . . . . . . . . . . . . . . . . . . 13 1.2.4 Network layer . . . . . . . . . . . . . . . . . . . . . . . 14 1.2.5 Transport layer

483

Solar energy conversion with hot electrons from impact ionisation  

Microsoft Academic Search

Impact ionisation in combination with carrier-carrier scattering in the absence of phonon scattering in an illuminated semiconductor leads to an energy distribution of electrons in the conduction band and of holes in the valence band which is best described by a single Fermi-distribution with no splitting of quasi-Fermi-energies, but with a temperature different from the lattice temperature. To make proper

Peter Würfel

1997-01-01

484

Light-harvesting materials: Soft support for energy conversion  

SciTech Connect

To convert solar energy into viable fuel sources, coupling light-harvesting materials to catalysts is a critical challenge. Now, coupling between an organic supramolecular hydrogel and a non precious metal catalyst has been demonstrated to be effective for photocatalytic H2 production. Ryan M. Stolley and Mo