Energy Technology Data Exchange (ETDEWEB)

Conference paper regarding research in the use of freeze prevention for passive solar domestic water heating systems.

Energy Technology Data Exchange (ETDEWEB)

The expected interstellar antiproton spectrum arising from cosmic-ray interactions in the Galaxy is recalculated, and the modulation of both antiprotons and protons is calculated using a two-dimensional modulation model incorporating gradient and curvature drifts and a wavy current sheet as well as the usual diffusion, convection, and energy-loss effects. Significant differences in the antiproton/proton ratio for different solar magnetic field polarities are predicted as well as a 'low-energy' component for antiprotons below about 1 GeV. 28 refs.

Energy Technology Data Exchange (ETDEWEB)

This book comprises an up-to-date description of the astrophysical characteristics of the sun, including modern techniques used in solar research. Provides an historical background of solar research and techniques and covers the necessary astrophysics for solar studies, energy generation in the interior, the convection zone, the non- thermally heated layers, and solar wind are described in detail. Also considers the sun in relation to other stars, including information on its variable outputs of light, charged particles, and fields.

Energy Technology Data Exchange (ETDEWEB)

The receiver whose convective heat loss test results are presented was designed to absorb 5 MW of solar energy, using a molten salt working fluid. During the tests, this receiver was brought to a temperature of about 343 C by a small group of heliostats. Total receiver heat loss due to emitted radiation, conduction and convection was first determined, and the convection loss was established by calculating the radiation and conduction losses analytically and subtracting their sum from the total. Losses due to convection are found to be 1.43 percent of the total heat input.

Energy Technology Data Exchange (ETDEWEB)

Progress in the worldwide capability of predicting the convective energy loss from solar central receivers is reviewed. The significant advances in the past three years have been in experimental areas. Baseline measurements of the convective heat transfer from large high-temperature surfaces, e.g., a flat plate and a cubical cavity, have been completed and empirical correlations have been obtained. Theoretical modeling activities have not kept pace with the experimental advances, however. Currently, the primary theoretical emphasis is the development and testing of turbulence models suitable for buoyant flows. Three major needs have been identified: the measurement of convective energy losses from operating solar central receivers; the continued development of theoretical models in spite of the relatively slow progress to date; and the quantification of the effects of atmospheric ...

Science.gov (United States)

Convective losses arising from buoyancy driven flow were calculated for a two-dimensional model simulating a solar cavity receiver. The TEMPEST code, capable of fully three-dimensional coupled thermal-hydraulic transient calculations, was used for the simulation. Predicted velocity and temperature results for a 2.59 m deep by 2.88 m high rectangular cavity with an aperture opening of 1.72 m were used to determine convective losses for prescribed interior wall temperatures and cavity orientation. Velocity vector and temperature isotherm plots were used to analyze flow characteristics.

Energy Technology Data Exchange (ETDEWEB)

This paper presents a mathematical model to analyze the solar evaporation in a shallow pond in steady state, when the inlet flow rate, concentration, surface area and solar radiation are given. The simultaneous heat and mass transfer mechanisms are considered for quantifying the amount of evaporated water to the atmosphere and the actual absorbed heat by wastewater is calculated to obtain the bottom temperature of water pond. The heat losses to air by radiation and convection mechanisms are considered and the heat transmission across the water film is evaluated by the forced convection mechanism. 6 refs., 5 figs., 1 tab.

International Nuclear Information System (INIS)

Solar drier does not degrade any more the dried products with the manner of the products dried at the natural sun. The drying unit is composed mainly of a solar air collector and an enclosure of drying. The transformation of the solar radiation into heat is done thanks to the solar collector whose effectiveness is increased by the addition of suitable baffles in the mobile air vein. The efficiency of the collector reaches then 80. The hot air on the outlet side of the collector arrives in the enclosure of drying where the heat transfer with the product to be dried is done by convection. The kinetics drying study shows that in addition to the dependence of the temperature and air velocity of drying, the speed of drying also depends on fragmentation on the product to dry, and mainly, of the product surface in contact with the drying air. Thus, the hygrometry is reduced from 76 to 13 ...

Energy Technology Data Exchange (ETDEWEB)

The convection heat loss from cavity receiver in parabolic dish solar thermal power system can significantly reduce the efficiency and consequently the cost effectiveness of the system. It is important to assess this heat loss and subsequently improve the thermal performance of the receiver. This paper aims to present a comprehensive review and systematic summarization of the state of the art in the research and progress in this area. The efforts include the convection heat loss mechanism, experimental and numerical investigations on the cavity receivers with varied shapes that have been considered up to date, and the Nusselt number correlations developed for convection heat loss prediction as well as the wind effect. One of the most important features of this paper is that it has covered numerous cavity literatures encountered in various other engineering systems, such as those in electronic cooling ...

Energy Technology Data Exchange (ETDEWEB)

A 2-D model has been proposed to investigate the approximate estimation of the natural convection heat loss from modified cavity receiver of without insulation (WOI) and with insulation (WI) at the bottom of the aperture plane in our previous article. In this paper, a 3-D numerical model is presented to investigate the accurate estimation of natural convection heat loss from modified cavity receiver (WOI) of fuzzy focal solar dish concentrator. A comparison of 2-D and 3-D natural convection heat loss from a modified cavity receiver is carried out. A parametric study is carried out to develop separate Nusselt number correlations for 2-D and 3-D geometries of modified cavity receiver for estimation of convective heat loss from the receiver. The results show that the 2-D and 3-D are comparable only at higher angle of inclinations (60 {<=} {beta} {<=} 90 ) of the receiver. ...

Energy Technology Data Exchange (ETDEWEB)

Cavity type receivers are used extensively in concentrating solar thermal energy collecting systems. The Solar Total Energy Project (STEP) in Shenandoah, Georgia is a large scale field test for the collection of solar thermal energy. The STEP experiment consists of a large field array of solar collectors used to supplement the process steam, cooling and other electrical power requirements of an adjacent knitwear manufacturing facility. The purpose of the tests, conducted for this study, was to isolate and quantify the radiative, conductive, and convective components of total heat loss, and to determine the effects of operating temperature, receiver angle, and aperture size on cavity heat loss. An analytical model for radiative heat loss was developed and compared with two other methods used to determine radiative heat loss. A proposed convective heat loss ...

Energy Technology Data Exchange (ETDEWEB)

A simple theory for predicting the convective energy loss from side-facing cavity receivers in windless environments has been developed. The approach used is to determine the velocity distribution of the incoming air in the aperture plane (and thereby the rate of mass entrainment); and then to estimate the bulk temperature of the heated emerging air. The convective loss is then calculated from an energy balance. To illustrate this theory, numerical results applicable to the 2.15 meter cubic cavity being tested in the laboratory are provided.

Energy Technology Data Exchange (ETDEWEB)

The contents include: Detailed index for 1991; Data for November 1991--Solar-terrestrial environment, IUWDS alert periods (advance and worldwide), Solar activity indices, Solar flares, Solar radio emission, Stanford mean solar magnetic field; Data for October 1991--Solar active regions, Sudden ionospheric disturbances, Solar radio spectral observations, Cosmic ray measurements by neutron monitor, Geomagnetic indices; Late data--Cosmic ray measurements by neutron monitor (Climax February and May 1990, Deep River May-August 1991), Geomagnetic indices (Sudden commencements/Solar flare effects January-May 1991); Errata--August 1991 Geomagnetic activity indices.

Energy Technology Data Exchange (ETDEWEB)

Ferrofluids have promising potential for heat transfer applications, since advective transport in a ferrofluid can be readily controlled by using an external magnetic field. However, unlike conventional free or forced convection, ferrohydrodynamic convection is not yet well characterized. A full understanding of the relationship between an imposed magnetic field, the resulting ferrofluid flow, and the temperature distribution is a prerequisite for the proper design and implementation of applications involving thermomagnetic convection. The literature variously assumes constant magnetic fields, does not completely represent the variation in the imposed field, or its descriptions are inaccurate, since the fields do not comply with the Maxwell's equations of electromagnetism. We address this by simulating two-dimensional forced ...

UK PubMed Central (United Kingdom)

From the gross conservation laws of thermodynamics in a convecting material we derive a bound on the ratio of the rate of production of mechanical or magnetic energy to the rate of internal radioactive...Full Text Available

CERN Document Server

We demonstrate that a massive asymptotic giant branch (AGB) star is a good candidate as the main source of short-lived radionuclides in the early solar system. Recent identification of massive (4-8 solar masses) AGB stars in the Galaxy, which are both lithium- and rubidium-rich, demonstrates that these stars experience proton captures at the base of the convective envelope (hot bottom burning), together with high-neutron density nucleosynthesis with 22Ne as a neutron source in the He shell and efficient dredge-up of the processed material. A model of a 6.5 solar masses star of solar metallicity can simultaneously match the abundances of 26Al, 41Ca, 60Fe, and 107Pd inferred to have been present in the solar nebula by using a dilution factor of 1 part of AGB material per 300 parts of original solar nebula material, and taking into account a ...

Energy Technology Data Exchange (ETDEWEB)

Results are presented from a numerical model of the steady-state energy transfer in molten-salt-in-tube solar cavity receivers that includes convective energy transfer at a local (spatially resolved) level. Molten salt energy absorption and gray radiative transfer between all cavity surfaces are also included. This model is applied to the Molten Salt Subsystem Component Test Experiment (MSS/CTE) cavity receiver. Results for this receiver indicate the global (entire cavity) receiver thermal efficiency is invariant within a few percent to most parameters investigated, although front surface temperatures of the nonabsorbing walls vary considerably, and are particularly sensitive to the type of convective submodel used. Absorption efficiencies indicate the effects of the cavity enclosure environment. For all conditions investigated, tube inner wall temperatures remain under 855 K, ensuring that the salt remains chemically ...

Energy Technology Data Exchange (ETDEWEB)

This invention is concerned with a solar energy system for propelling aircraft. Obtained are forces for aerodynamic lift and impetus. The lifted body had a transparent upper surface for the sun light, but black or reflecting for IR-radiation and high thermal insulation properties. Inside of the lifted body, the air temperature increases and is lifted by convection influence. The air resistance of this body is low in horizontal direction and higher in vertical position. The payload could be shifted, so that the positive or negative angle of the whole body can be selected. By this principal it is possible to transform the static lifting force in a dynamic impetus.

Energy Technology Data Exchange (ETDEWEB)

The authors investigate the optimisation of solar-heated cavity receivers in which solar energy collected by a paraboloid collector is converted into electrical energy. The focussed solar energy enters the receiver through an aperture to heat the working fluid, which flows inside the receiver tubes and is compressed by the compressor of a gas turbine system, to the highest process temperature. A method of calculating the distribution on the inner receiver surfaces of the solar radiation reflected by the paraboloid collector is presented to begin with. The interchange of radiant energy inside the receiver cavity can be calculated on this basis, including the radiation loads, the temperatures of the inner receiver walls, and the radiative and convective losses. The temperature fields in the tube walls must be known for determining the strength required of receiver tubes; they can be ...

International Nuclear Information System (INIS)

A numerical and experimental investigation is carried out in a solar thermochemical reactor for the thermal dissociation of ZnO at 2000 K using concentrated solar energy. The reactor consists of a cavity-receiver lined with ZnO particles and directly exposed to high-flux irradiation. A transient heat transfer model is formulated to link the rate of radiation, convection, and conduction heat transfer to the reaction kinetics. The radiosity and Monte Carlo methods are applied to obtain the distribution of net radiative fluxes at the internal surfaces of the reactor cavity and at the surface of the ZnO bed. Validation is accomplished in terms of the calculated and measured transient temperature profiles and chemical reaction rates.

Energy Technology Data Exchange (ETDEWEB)

In this study we discuss an unsteady free convection MHD flow past semi-infinite vertical porous plate. We have considered the flow in the presence of a strong magnetic field and therefore the electromagnetic force is very large. This brings in the phenomenon of Hall and Ion-slip currents. The effects of these two parameters together with that of viscous dissipation and radiation absorption among others on velocity, temperature and concentration profiles are presented. The profiles are presented graphically. As the partial differential equations governing this problem are highly non-linear they are solved numerically by a finite difference method. It is found that in presence of heating of the plate by free convection current the velocity boundary layer thickness decreases.

British Library Electronic Table of Contents (United Kingdom)

This paper is devoted to investigate the influences of thermal dispersion and magnetic field on a hot semi-infinite vertical porous plate embedded in a saturated Darcy-Forchheimer-Brinkman porous medium. The coefficient of thermal diffusivity has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. The effects of transverse magnetic field parameter (Hartmann number Ha), Reynolds number Re (different velocities), Prandtl number Pr (different types of fluids) and dispersion parameter on the wall shear stress and the heat transfer rate are discussed.

British Library Electronic Table of Contents (United Kingdom)

In this paper, the unsteady MHD free convection heat and mass transfer of viscous fluid flowing through a Darcian porous regime adjacent to a moving vertical semi-infinite plate under Soret and Dufour effect have been examined. Viscous dissipation effects are included in the energy equation. A uniform magnetic field is applied transversely to the direction of the flow. The differential equations governing the problem have been transformed by a similarity transformation into a system of non-dimensional differential equations which are solved numerically by element free Galerkin method. The influence of Grashof number (Gr), magnetic parameter (M), heat absorption parameter (Q), permeability parameter (K), Schmidt number (Sc), Soret number (Sr), and Dufour number (Du) on the velocity, tempera...

Energy Technology Data Exchange (ETDEWEB)

Direct current motors are used in photovoltaic systems. Important characteristics of electric motors are the starting to rated current and the torque ratios. These ratios are dictated by the size of the solar cell array and are different for the various dc motor types. The paper deals with the calculation of the starting to rated current ratio and starting to rated torque ratio of the permanent magnet, separately, series and shunt excited motors when powered by solar cells for the two cases: where (1) the system includes a maximum-power-point-tracker (MPPT) and (2) without an MPPT. Comparing these two cases, one gets a torque magnification of about 3 for the permanent magnet motor and about 7 for other motor types at rated design insolation. The calculation of the torques may assist the PV system designer to determine the advantage of including an MPPT in the system as far as the starting ...

CERN Document Server

Many sunspot cycles are double peaked. In 1967 Gnevyshev suggested that actually all cycles have two peaks generated by different physical mechanisms, but sometimes the gap between them is too short for the maxima to be distinguished in indices of the total sunspot activity. Here we show that indeed all cycles have two peaks easily identified in sunspot activity in different latitudinal bands. We study the double peaks in the last 12 sunspot cycles and show that they are manifestation of the two surges of toroidal field - the one generated from the poloidal field advected all the way on the surface to the poles, down to the tachocline and equatorward to sunspot latitudes, and another one generated from the poloidal field diffused at midlatitudes from the surface to the tachocline and transformed there into toroidal field. The existence of these two surges of toroidal field is due to the relative magnitudes of the speed of the large-scale solar meridional ...

Science.gov (United States)

Not Available

Energy Technology Data Exchange (ETDEWEB)

Generation of anomalous resistivity and dynamical development of collisionless reconnection in the vicinity of a magnetically neutral sheet are investigated by means of a three-dimensional particle simulation. For no external driving source, two different types of plasma instabilities are excited in the current layer. The lower hybrid drift instability (LHDI) is observed to grow in the periphery of current layer in an early period, while a drift kink instability (DKI) is triggered at the neutral sheet in a late period as a result of the nonlinear deformation of the current sheet by the LHDI. A reconnection electric field grows at the neutral sheet in accordance with the excitation of the DKI. When an external driving field exists, the convective electric field penetrates into the current layer through the particle kinetic effect and collisionless reconnection is triggered by the convective electric field earlier than the ...

Energy Technology Data Exchange (ETDEWEB)

The pathway to hydrogen generation entirely from renewable energy and material sources probably goes by a transitional period with the utilization of hybrid fossil/renewable integrated systems. Solar steam reforming of methane is set in this context, specifically suited for a country like Italy whose actual energy policy is mainly based on the imported NG, but also characterized by convenient solar radiation levels in the Southern Regions. A new solar SMR process is being developed by ENEA, using molten nitrates as solar heat carriers and storage medium at about 550 C. The potential of this process have been proved theoretically by process simulation studies. Engineering and experimental activities aimed to the development of a prototype apparatus are now in progress in ENEA's laboratories. It is remarkable that the developed technology (MS powered SMR) can find interesting impact in the in ...

Energy Technology Data Exchange (ETDEWEB)

Thermal hydraulics of a liquid metal is important to design the blanket of a magnetic confined fusion reactor. Since a liquid metal has high thermal and electrical conductivity, the flow characteristics are often different from those of an ordinary liquid like water especially in thermal convection and under a magnetic field. It is difficult to simulate such flows in a liquid metal cooled blanket by water. Flow visualization is a popular method to study thermal hydraulics. Since most of metals are visible by neutron rays, neutron radiography is available to the flow visualization of a liquid metal. The purpose of this study is to develop a visualization technique of the flow in a liquid metal by real-time neutron radiography using the tracer and the dye injection methods. A real-time thermal neutron radiography system of JRR-3M in Japan Atomic Energy Research Institute was used for the visualization test.

Energy Technology Data Exchange (ETDEWEB)

Long-term modulation of galactic cosmic rays in interplanetary magnetic field (IMF) turbulence is a fundamental subject for understanding the connection between cosmic ray transport and solar activity. The discovery of a new cosmic ray modulation phenomenon is reported. Analysis of neutron monitor data has revealed that the difference in amplitude of the cosmic ray diurnal anisotropy for IMF sectors directed toward and away from the Sun displays a solar cycle variation. Neutron monitor data recorded at Climax, Deep River, Hyancayo, Kiel, Mt. Washington, and Swarthmore/Newark over the period 1957 to 1988 show that the amplitude difference varied between approximately 0.1 to -0.1 percent, with peaks in 1960, 1972, and 1982. A theoretical expression for this difference was derived from a three-dimensional model. Analysis also showed that the latitudinal density gradient of cosmic rays changed between 1.6 and -1.6 percent/AU ...

Energy Technology Data Exchange (ETDEWEB)

This paper investigates the phase change behavior of 65 mol% capric acid and 35 mol% lauric acid, calcium chloride hexahydrate, n-octadecane, n-hexadecane, and n-eicosane inside spherical enclosures to identify a suitable heat storage material. Analytical models are developed for solidification and melting of sphere with conduction, natural convection, and heat generation. Both the models are validated with previous experimental studies. Good agreement was found between the analytical predictions and experimental study and the deviations were lesser than 20%. Heat flux release at the wall, cumulative energy release to the external fluid, are revealed for the best PCM. The influence of the size of encapsulation, initial temperature of the PCM, the external fluid temperature on solidified and molten mass fraction, and the total phase change time are also investigated. (author)

CERN Document Server

We present constraints on theoretical models of Type Ia SNe using spatially resolved ASCA X-ray spectroscopy of four galaxy clusters: Abell 496, Abell 2199, Abell 3571 & Perseus. All four clusters have central Fe abundance enhancements and an ensemble of abundance ratios are used to show that most of the Fe in the central regions of the clusters comes from SN Ia. At the center of each cluster, simultaneous analysis of spectra from all ASCA instruments shows that the Ni to Fe abundance ratio (normalized by the solar ratio) is ~ 4. We use the Ni/Fe ratio as a discriminator between SN Ia explosion models: the Ni/Fe ratio of ejecta from the "Convective Deflagration" model W7 is consistent with the observations, while those of "delayed detonation" models are not consistent at the 90% confidence level.

Energy Technology Data Exchange (ETDEWEB)

A review of theoretical and observational research on the magnetopause during 1987-1990. Starting with recent work on magnetic reconnection, the review proceeds to magnetopause surface wave phenomena, including the controversy over the role of solar wind pressure pulses in the coupling process and in the mimicking of flux transfer events signatures, and finishes with the magnetopause structure and associated wave phenomena. Recent advances in computer modeling of the magnetopause and the pertinent processes are also discussed. 108 refs.

Energy Technology Data Exchange (ETDEWEB)

We review the data on long-term changes in the solar diurnal variation of cosmic rays, observed at Deep River with a neutron monitor and at Embudo with an underground muon telescope, during the period 1965-1976. We show that the model proposed by Erdos and Kota (1979, Sixteenth ICCR, Kyoto. Conference Papers 4, 45). cannot explain the systematic changes seen in our data during 1971-1976. An insight gained from the diffusion-convection model enables us to obtain a unique solution for K parallel to Gsub(r) in terms of the parameters applicable to the solar wind and the diurnal anisotropy. This helps us calculate the rigidity (R) dependence of the diffusion coefficent K parallel. We find that K parallel = 1.37 x 10/sup 18/ Rsup(0.6) m/sup 2/s/sup -1/, where R is in gigavolts, and K perpendicular 1.08 x 10/sup 18/ m/sup 2/s/sup -1/. Our results are discussed.

Energy Technology Data Exchange (ETDEWEB)

As an explosion develops in the collapsed core of a massive star, neutrino emission drives convection in a hot bubble of radiation, nucleons, and pairs just outside a proto-neutron star. Shortly thereafter, neutrinos drive a wind-like outflow from the neutron star. In both the convective bubble and the early wind, weak interactions temporarily cause a proton excess (Y{sub e} {approx}> 0.50) to develop in the ejected matter. This situation lasts for at least the first second, and the approximately 0.05-0.1 M{sub {circle_dot}} that is ejected has an unusual composition that may be important for nucleosynthesis. Using tracer particles to follow the conditions in a two-dimensional model of a successful supernova explosion calculated by Janka, Buras, and Rampp (2003), they determine the composition of this material. most of it is helium and {sup 56}Ni. The rest is relatively rare species produced by the decay of proton-rich isotopes unstable ...

Science.gov (United States)

... For other aquatic systems, detailed diel observations of both water temper- ature and periods of flow will be necessary to estimate convective ...

British Library Electronic Table of Contents (United Kingdom)

In this article, we studied the effects of variable viscosity and thermal conductivity on an unsteady two-dimensional laminar flow of a viscous incompressible conducting fluid past a semi-infinite vertical porous moving plate taking into account the effect of a magnetic field in the presence of variable suction. The fluid viscosity is assumed to vary as an inverse linear function of temperature but the thermal conductivity is assumed to vary as a linear function of temperature. It is assumed that the porous plate moves with a constant velocity in the direction of fluid flow, and the free stream velocity follows the exponentially increasing small perturbation law. The governing equations for the flow are transformed into a system of nonlinear ordinary differential equations by perturbation ...

British Library Electronic Table of Contents (United Kingdom)

An analysis is presented for the effects of chemical reaction and thermal radiation on hydromagnetic free convection heat and mass transfer for a micropolar fluid via a porous medium bounded by a semi-infinite vertical porous plate in the presence of heat generation. The plate moves with a constant velocity in the longitudinal direction and the free stream velocity follows an exponentially small perturbation law. A uniform magnetic field acts perpendicularly to the porous surface in which absorbs the micropolar fluid with a suction velocity varying with time. Analytical expressions are computed numerically. Numerical calculations are carried out the purpose of the discussion of the results which are shown on graphs and the effects of the various dimensionless parameters entering into the p...

Energy Technology Data Exchange (ETDEWEB)

This report uses experimental data to compare the performance of two sodium cooled solar central receivers operated at the International Energy Agency Small Solar Power Systems project near Almeria, Spain. Performance includes point-in-time steady state efficiency, average efficiency, start-up time, and operation time. Point-in-time steady state efficiency calculations were based on the statistical method of least squares using receiver incident and absorbed powers. One receiver, a cavity type, showed a peak steady state receiver efficiency of 87% +- 5% and an average efficiency of about 67%. The other receiver, an external ''billboard'' type, had a peak steady state receiver efficiency of 96% +- 4% and an average efficiency of about 79%. The original design peak steady state efficiency predictions for both receivers were within the experimentally determined 95% probability interval. Thermal loss test data ...

Science.gov (United States)

Thin film solar cells and solar cell testing - photovoltaic cells, radiation damage to cadmium sulfide solar cells, and airplane testing of solar cells

Energy Technology Data Exchange (ETDEWEB)

Characteristics of pressure drop and heat transfer have been investigated for a lithium single-phase flow and a helium-lithium two-phase flow in a horizontal conducting circular channel in the presence of a uniform transverse magnetic field up to 1.4 T as related to the lithium cooling for magnetic-confinement fusion reactors. By the application of the magnetic field to the lithium single-phase flow, remarkable heat transfer enhancement has been observed at the top wall due to the suppression of the mixed convection occurring in the low Peclet number range, while appreciable heat transfer deterioration appeared in the high Peclet number range. It has been confirmed that the helium-lithium two-phase flow can reduce the high magnetohydrodynamic (MHD) pressure drop in a lithium single-phase flow, and it can provide much better heat transfer performance than that in a helium single-phase flow. In the ...

CERN Document Server

Solar wind effect on the muon flux at sea level

International Science & Technology Center (ISTC)

Elaboration of Electrochemical Solar Energy Converter Incorporating Cadmium Selenide Semiconductor Developed Electrochemically

International Nuclear Information System (INIS)

... range magnetic fields magnetic susceptibility magnetization neutron diffraction

International Nuclear Information System (INIS)

Short communication.

KoreaScience (Korea)

Full Text Available

Science.gov (United States)

Not Available

Norwegian Open Research Archives (NORA)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The article is the second part of a review dealing with latest developments in the area of solar cell technologies and application. Physical principles, design and efficiency as well as advantages and disadvantages of GaAs- and CdS-solar cells are described. Power generation solar cell systems with voltage converters, combined solar cell/solar collector systems and thermoelectric solar systems are presented in the second part of the article.

Science.gov (United States)

When induced by bottom heating in a horizontal fluid layer which is characterized by forced motion or solute stratification, buoyancy-driven flows may assume a variety of forms. The flows, which are examples of mixed or double-diffusive convection, can strongly influence heat tranfer or the entrainment of stratified fluid. General aspects of each form of convection are reviewed, and emphasis is placed on mixed convection in a horizontal rectangular channel and on double-diffusive convection due to thermally driven mixed-layer development in a solutally stratified fluids. Flow conditions are described, and experimental and theoretical results are presented for related heat-transfer and entrainment parameters.

Science.gov (United States)

... Solar Cell Radiation Respinnse Near the Interface o~f fliffprerv- ... 5 4. CALCUTl-ATED SOLAR CELL RLSPONSE FOR VARIOUS BASE MATERIALS ...

British Library Electronic Table of Contents (United Kingdom)

Spacecraft studies of the three terrestrial planets with atmospheres have made it possible to make meaningful comparisons that shed light on their common origin and divergent evolutionary paths. Early in their histories, all three apparently had oceans and extensive volcanism; Mars and Earth, at least, had magnetic fields, and Earth, at least, had life. All three currently have climates determined by energy balance relationships involving carbon dioxide, water and aerosols, regulated by solar energy deposition, atmospheric and ocean circulation, composition, and cloud physics and chemistry. This paper addresses the extent to which current knowledge allows us to explain the observed state of each planet, its planetology, climatology and biology, within a common framework. Areas of ignorance...

CERN Document Server

Observations show the ubiquitous presence of propagating magnetohydrodynamic (MHD) kink waves in the solar atmosphere. Waves and flows are often observed simultaneously. Due to plasma inhomogeneity in the perpendicular direction to the magnetic field, kink waves are spatially damped by resonant absorption. The presence of flow may affect the wave spatial damping. Here, we investigate the effect of longitudinal background flow on the propagation and spatial damping of resonant kink waves in transversely nonuniform magnetic flux tubes. We combine approximate analytical theory with numerical investigation. The analytical theory uses the thin tube (TT) and thin boundary (TB) approximations to obtain expressions for the wavelength and the damping length. Numerically, we verify the previously obtained analytical expressions by means of the full solution of the resistive MHD eigenvalue problem beyond the TT and TB approximations. ...

Energy Technology Data Exchange (ETDEWEB)

The article describes the Solair 1 solar cell-powered aircraft. Measures to reduce the weight of the craft are cited.

Energy Technology Data Exchange (ETDEWEB)

Power spectral analysis of cosmic ray intensity recorded by neutron monitors at Calgary and Deep River, Alberta, was carried out over a wide range of frequencies from 3 {times} 10{sup {minus}9} Hz to 6 {times} 10{sup {minus}6} Hz during the epoch 1965-1989 and revealed different behavior of the power spectral density for the three ranges of frequency domains. At low frequencies corresponding to the periodicity T {approx} 20 months the power spectrum shows an abrupt change in the level and profile of power spectral density (PSD). This indicates that the processes responsible for the long period variations are different from the one which causes short-period variations. At middle frequencies corresponding to periodicities between 6 and 18 months, the PSD indicates that the periodicities are not stable and show a transient character over the entire epochy of analysis. The PSD for periods T {approx} 27 days indicates an 11 year recurring tendency related to solar ...

Science.gov (United States)

We use a massively parallel 3D hybrid particle code, dHybrid, to simulate the deflection of plasma beams by a dipole like magnetic field in a laboratory environment. Dipole magnetic fields, along with a plasma injection source to inflate the magnetic field, are now being studied as means of deflecting solar wind and Energetic Particles away from spacecrafts [1,2,3]. We have considered three setups, consistent with the experiments, with a plasma beam fired at i) a dipole field with no plasma injection, ii) a plasma injection source with no dipole field and iii) a dipole field with a plasma injection source. The hybrid simulations help understand the relevant physical phenomena, and enable extrapolation to space plasma scenarios, where setups are similar but plasma parameters differ significantly. The simulation results consistently show the plasma beam being deflected by the dipole field, in the first ...

Energy Technology Data Exchange (ETDEWEB)

The buoyancy driven convective flow fields are steady circulatory flows which were made between surfaces maintained at two fixed temperatures. They are ubiquitous in nature and play an important role in many engineering applications. Especially, in last decades, natural convection in a close loop or cavity becomes the main issue in the molecular biology for the polymerase chain reaction (PCR). Application of a natural convection can reduce the costs and efforts remarkably. This paper focuses on the sensitivity study of turbulence analysis using CFD for a natural convection in a closed rectangular cavity. Using commercial CFD code, FLUENT, various turbulent models were applied to the turbulent flow. Results from each CFD model will be compared each other in the viewpoints of flow characteristics. This work will suggest the best turbulent model of CFD for analyzing turbulent flows of the natural ...

Energy Technology Data Exchange (ETDEWEB)

The theoretical analysis of a partially-ionized hydrogen gas flow (gas temperatures of approximately 10,000 to 20,000 K) through a particular class of magnetohydrodynamic (MHD) generators and the preliminary design of these MHD generators as open cycle, electric power supplies are performed. Analysis of the gas flow through these ultra-high temperature MHD generators requires a coupled gas dynamics/radiative heat transfer solution. Gas dynamics are modeled by a set of quasi-one-dimensional, nonlinear differential equations which account for friction, convective and radiative heat transfer and the interaction between the ionized gas and applied magnetic field. Radiative heat transfer is modeled using non-gray, absorbing-emitting two- and three-dimensional P-1 approximations which permit an arbitrary variation of the spectral absorption coefficient with frequency. Gas dynamics and radiative heat transfer are coupled through the energy equation, ...

Energy Technology Data Exchange (ETDEWEB)

Several low-mass models with an inhomogeneous radiative core and a convective envelope are investigated, the entire core or its upper portion being treated as a zone of neutral stability. Mixing by convective overshoot will then give rise to unstable structure.

Science.gov (United States)

Characteristics of inertia gravity waves associated with convection are investigated in the lower stratosphere using high-resolution radiosonde data observed from 18 June to 15 July of 2005 and 2007 in Korea. Three-dimensional ray-tracing model and reanalysis data are used to investigate the propagation and the sources of the observed waves. The observed waves associated with convections are discriminated based on the existence of convections when and where the rays reach the average height range of convective clouds. Waves observed in 2005 and 2007 show similar spectral characteristics, but wave energy in 2007 is significantly larger than in 2005. The observed waves propagate from three source regions: the northeastern, southeastern, and western regions around Korea. They show preferential propagation directions based on their sources, and convections from the western region ...

UK PubMed Central (United Kingdom)

Convection-enhanced drug delivery (CED) is a novel approach to delivering drugs into brain tissue. Drugs are delivered continuously via a catheter, enabling large volume distributions of high drug concentrations...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In order to illustrate morphological features and variations of temperature in the upper thermosphere, we performed numerical simulations with a whole atmosphere general circulation model (GCM) for the solar minimum and geomagnetically quiet conditions in March, June, September, and December. In previous GCMs, tidal effects were imposed at the lower boundaries assuming dominant diurnal and semi-diurnal tidal modes. Since the GCM used in the present study covers all the atmospheric regions, the atmospheric tides with various modes are generated within the GCM. The global temperature distributions obtained from the GCM are in agreement with ones obtained from NRLMSISE-00. In addition, the GCM also represents localised temperature structures which are superimposed on the global day-night distributions. These localised structures, which vary from hour to hour, would be observed as variations with periods of about 2-3 h at a single site. The amplitudes of the 2-3 h ...

Science.gov (United States)

... small water or ice particles by impaction ... flight recording; principally the hydrometeor charge unit ... capability of directing aircraft movements by radio ...

International Nuclear Information System (INIS)

(1973). United States Kylstra, CD West Palm Beach, Florida, USA. 25 Apr 1973.

Energy Technology Data Exchange (ETDEWEB)

In this study the authors examine the convective cooling provided by fluid trapped in the cavity between two consecutive rollers in a roller bearing. In order to calculate the steady-state temperature of the roller, the designer must know nor only the rolling-contact heat input received by the roller but also the convection cooling effect of the surrounding fluid. Until recently, this lateral convection cooling effect was modeled by assuming a certain (constant) heat transfer coefficient h at the roller surface, and then calculating the steady-state temperature distribution around the roller.

Energy Technology Data Exchange (ETDEWEB)

Calculations have been performed to study the dependence on model parameters of convectively heating the region interior to the core convection zone for core helium flash models. We find that interior heating always occurs on a time scale significantly shorter than the evolutionary time scale even at the peak of the flash.

Energy Technology Data Exchange (ETDEWEB)

The Meteorological Service of Canada has made weather datasets available in real-time on the Internet, for use by those with an interest in solar applications. Ensemble weather models can be used to produce medium range forecasts of weather events and to predict the likely available kilowatt-hours (kWhrs) of solar energy. As such, solar sites can maximize their harvest and use of solar energy. This presentation highlighted several different types of renewable energy forecasts obtained from weather models, including forecasts of expected kWhrs from solar panels and wind turbines, daily forecasts of expected solar heated water volumes and forecasts of water collection potential from impending precipitation events. The value of renewable energy forecasts in helping the solar energy sector monitor daily energy loads as well as daily and weekly ...

Energy Technology Data Exchange (ETDEWEB)

Thermal absorption with its combined thermal and mechanical loads in a solar receiver does depend significantly on the distribution of incident solar radiation. For a cavity receiver with paraboloid collectar a method is derived which enables the calculation of solar radiation distribution on the areas inside the receiver. The theoretical bases are presented first, and a subsequent example shows the influence of the most important geometric parameters on the distribution of solar radiation.

Energy Technology Data Exchange (ETDEWEB)

In the paper, a potential of solar energy for drying of medicinal plants in Polish conditions is estimated and development of solar drying technologies is presented. The results of economic assessment of flat-plate solar collectors applied for drying of medicinal plants on a farm are promising. In some specific conditions, e.g. drying of wild grown medicinal plants in remote areas, even application of photovoltaic modules for driving of a fan of a solar dryer is a profitable option and enables easy control of the drying air temperature.

Science.gov (United States)

... Title : Refining the Magnetic Forming Capability. ... Abstract : The purpose of this project was to refine the in-house magnetic forming capability. ...

Science.gov (United States)

... Examples include magnetic forming tools, magnetic shielding, magnetohydrodynamic propulsion systems, and various magnetic containment ...

CERN Document Server

The influence of extended convective mixing (overshoot) on asymptotic giant branch stellar evolution is investigated in detail. The extended mixing is treated time-dependently, and the efficiency declines exponentially with the geometric distance from the convective boundary. It has been considered at all convective boundaries, including the He-flash convection zone in the intershell region which forms during the thermal pulses. Both the structural and the chemical evolution are affected by the inclusion of overshoot. The main results include a very efficient third dredge-up which leads to the formation of carbon stars of low mass and luminosity. A C13 pocket which may serve as a neutron source for the s-process can form after the third dredge-up has reached into the C12 rich intershell. Overshoot applied to the pulse-driven convective zone during the He-flash leads to a deeper ...

Science.gov (United States)

The PVSCAN is an instrument designed to characterize silicon solar cell materials and devices. It performs a host of measurements that yield spatial maps of dislocation density, grain distribution, reflectance, and photoresponses from near-junction and the bulk of a solar cell.

CERN Document Server

PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays of galactic, solar, and trapped nature in a wide energy range protons: 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50 MeV-270 GeV) and search for antimatter with a precision of the order of 10^-8). The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June, 15, 2006 in a 350*600 km orbit with an inclination of 70 degrees. The detector is composed of a series of scintillator counters arranged at the extremities of a permanent magnet spectrometer to provide charge, Time-of-Flight and rigidity information. Lepton/hadron identification is performed by a Silicon-Tungsten calorimeter and a Neutron detector placed at the bottom of the device. An Anticounter system is used offline to reject false triggers coming from the satellite. In ...

International Nuclear Information System (INIS)

The article describes the energy in Lebanon. In 1995, 97% of the imported energy was based on hydrocarbons. Fuel and gas oil present 66% of the final energy. Air pollution is mainly caused by the transportation sector (vehicles and buses...) which presents 70% of the global atmospheric pollution. Renewable energy such as biomass, fossil energy, hydro-energy, solar energy... are also described. The solar energy was defined as a best solution that preserve health in Lebanon. The different applications of the solar for energy production is discussed: photovoltaic , thermal heating, sanitary hot water, electrical heaters, solar water heaters...In conclusion, solar heaters economize 80% of the annual energy expenses

Science.gov (United States)

Manufacture of cadmium sulfide thin film solar cells

Energy Technology Data Exchange (ETDEWEB)

A module is described with a receiver having a solar energy acceptance opening and supported by a mounting ring along the optic axis of a parabolic mirror in coaxial alignment for receiving solar energy from the mirror, and a solar flux modulator plate for varying the quantity of solar energy flux received by the acceptance opening of the module. The modulator plate is characterized by an annular, plate-like body, the internal diameter of which is equal to or slightly greater than the diameter of the solar energy acceptance opening of the receiver. Slave cylinders are connected to the modulator plate for supporting the plate for axial displacement along the axis of the mirror thereby shading the opening with respect to solar energy flux reflected from the surface of the mirror to the solar energy acceptance opening.

Science.gov (United States)

Oct 15, 1985 ... Title: Laser-assisted solar cell metallization processing. No Digital Version Available: Go to Tips on Ordering ...

UK PubMed Central (United Kingdom)

Three patients are described with foveal lesions resembling minute holes following trauma. The similarity of the lesions to foveomacular retinitis and solar retinopathy suggests that all these conditions...Full Text Available

Science.gov (United States)

Sputtering of glass coatings on cadmium sulfide thin film solar cells

Energy Technology Data Exchange (ETDEWEB)

In Canada, the cost of heating is a major expense in the operation of greenhouses in the winter season, inhibiting greenhouse production in winter months in most part of the country. Alternative energy sources, such as solar energy and biomass energy may offer an economically feasible heating alternative. A solar energy greenhouse technology developed in northern China for winter vegetable production has demonstrated good potential for Manitoba winter conditions. The design and performance of solar energy greenhouses depend on the geographical location. Therefore, in order to optimize the design of solar greenhouses with respect to the latitude of the location for maximum solar radiation gain, a theoretical analysis was performed that analyzed parameters such as greenhouse length and the roof slope. This paper described the methodology of the study, including a description of ...

Science.gov (United States)

Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly

Science.gov (United States)

Necessary theoretical foundation is given for the treatment of magnetic stresses applied to

KoreaScience (Korea)

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Science.gov (United States)

Discussion of an electrohydraulic and magnetic forming process

Energy Technology Data Exchange (ETDEWEB)

Ion diamagnetic effects on the m=1 (poloidal mode number) and n=1 (toroidal mode number) kinetic internal kink mode are studied numerically by the three-field gyro-reduced-MHD code in the cylindrical coordinates, GRM3F-CY. In the derivation of the gryo-reduced-MHD model including the ion diamagnetic effects, finite gyroradius effects of ions are added to the gyrokinetic Poisson equation (quasi-neutral condition) and the convection term of the conservation law of the ion density. It is found that the long wavelength approximation, ksub(perpendicular) {rho}{sub ti} << 1, where ksub(perpendicular) is the wavenumber perpendicular to the magnetic field and {rho}{sub ti} is the thermal ion gyroradius, fails to reproduce the correct dispersion relation; the formulation valid even for ksub(perpendicular) {rho}{sub ti} >> 1 is necessary. The results of numerical calculation coincide with the theory for |{omega}{sub ...

International Nuclear Information System (INIS)

The onset of double-diffusive convection in a couple-stress fluid-saturated horizontal porous layer is studied using linear and weak nonlinear stability analyses. The modified Darcy equation that includes the time derivative term and the inertia term is used to model the momentum equation. The expressions for stationary, oscillatory and finite-amplitude Rayleigh number are obtained as a function of the governing parameters. The effect of couple-stress parameter, solute Rayleigh number, Vadasz number and diffusivity ratio on stationary, oscillatory and finite-amplitude convection is shown graphically. It is found that the couple-stress parameter and the solute Rayleigh number have a stabilizing effect on stationary, oscillatory and finite-amplitude convection. The diffusivity ratio has a destabilizing effect in the case of stationary and finite-amplitude modes, with a dual effect in the case of oscillatory ...

British Library Electronic Table of Contents (United Kingdom)

This paper deals with a mixed convection water flow in a horizontal rectangular duct, uniformly heated from one lateral vertical wall and thermally insulated elsewhere. The supplied heat flux induces a secondary flow, which structure is constituted of one longitudinal roll in the considered aspect ratio (??=?1.9), embedded into a return flow of possibly large stream wise extension (up to twenty channel heights). Such situation induces helicoidal trajectories for the fluid flow particles, which contributes to a heat transfer enhancement compared to purely forced convection flow.

Energy Technology Data Exchange (ETDEWEB)

The paper describes an analytical study of two parallel-flowing boundary layers of free and forced convection modes on the facing sides of a vertical thin wall. The two layers are analyzed separately within the framework of boundary layer theory, and coupled by the matching conditions at wall. Numerical data are obtained for a wide range of a dimensionless conjugation parameter {zeta} relating the heat transfer effectiveness of two convection modes. Based on these data, an expression for calculating the conjugate mean Nusselt number as a function of {zeta}-parameter is found by means of a curve-fitting method. (orig.)

Energy Technology Data Exchange (ETDEWEB)

The conception of a solar receiver intended to equip a tower power-station has to combine multiple requirements: very highly concentrated solar flux, unsteady in time and space; necessity to obtain a high efficiency; respect of the physical limits of the materials and of the fluid. The description of Themis solar receiver and of its operation is preceded by considerations which have led to the choice of the cavity, of the fluid and of its circulation.

International Nuclear Information System (INIS)

... cadmium sulfides communications electrons performance testing physical

Science.gov (United States)

Orbital maintenance parameters for individual satellites or groups of satellites have traditionally

Energy Technology Data Exchange (ETDEWEB)

A set of nomographs is presented which can be used to estimate the average annual solar fraction for solar space and water heating at a large number of DOD facilities. The solar fraction estimated from the nomograph is in close agreement with F-Chart 3.0 and allows for variation of the following parameters: annual load, collector area, collector transmittance-absorptance coefficient, and collector overall loss coefficient.

Science.gov (United States)

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KoreaScience (Korea)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A preliminary study of two different kinds of solar receivers (a rotating cavity receiver and a volumetric receiver) suitable to operate in the 1 kW solar facility at the University of Rome is presented. Possible applications of solar energy in the aluminum extraction from leucite and chemical storage by the CuO/Cu[sub 2]O cycle are presented and discussed. (author).

Science.gov (United States)

The influence of ablation on stagnation region convective heating for ... and thermal properties of this fiber depend on the fluorination process ... However, these properties are between those of graphite and those of PTFE (Teflon). ...

CERN Document Server

Dark Matter annihilation (DMA) may yield an excess of gamma rays and antimatter particles, like antiprotons and positrons, above the background from cosmic ray interactions. The excess of diffuse Galactic Gamma Rays from EGRET shows all the features expected from DMA. The new precise measurements of the antiproton and positron fractions from PAMELA are compared with the EGRET excess. It is shown that the charged particles are strongly dependent on the propagation model used. The usual propagation models with isotropic propagation models are incompatible with the recently observed convection in our Galaxy. Convection leads to an order of magnitude uncertainty in the yield of charged particles from DMA, since even a rather small convection will let drift the charged particles in the halo to outer space. It is shown that such anisotropic propagation models including convection prefer a contribution from ...

British Library Electronic Table of Contents (United Kingdom)

Experimental investigations have been performed to study solutal convection around an air bubble squeezed between the walls of a horizontal rectangular channel, filled by an aqueous solution of surfactant with vertically stratified concentration. A convective motion in the fluid develops due to the solutocapillary Marangoni forces at the bubble lateral free surface. The structure and evolution of the convective flow and the surfactant concentration fields in the channel have been investigated using interferometric technique. The tests revealed the development of self-oscillatory modes near the bubble surface, related to the interaction between solutocapillary and solutogravitational motion mechanisms. The time dependences of the oscillations period are analyzed in relation to the average c...

Science.gov (United States)

The influence of ablation on stagnation region convective heating for ... and thermal properties of this fiber depend on the fluorination process ... However, these properties are between those of graphite and those of PTFE (Teflon). ...

Energy Technology Data Exchange (ETDEWEB)

A solar thermal powered aircraft powered by heat energy from the sun. A Rankine-Brayton hybrid cycle heat engine is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller or other mechanism for enabling sustained free flight. The Rankine-Brayton engine has a thermal battery, preferably containing a lithium-hydride and lithium mixture, operably connected to it so that heat is supplied from the thermal battery to a working fluid. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, ...

CERN Document Server

Several observational studies suggest that solar wind dynamic pressure fluctuations can drive magnetospheric ultra-low frequency (ULF) waves on the dayside. To investigate this causal relationship, we present results from Lyon-Fedder-Mobarry (LFM) global, three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind-magnetosphere interaction. These simulations are driven with synthetic solar wind input conditions, where idealized ULF dynamic pressure fluctuations are embedded in the upstream solar wind. In three of the simulations, a monochromatic, sinusoidal ULF oscillation is introduced into the solar wind dynamic pressure time series. In the fourth simulation, a continuum of ULF fluctuations over the 0-50 mHz frequency band is introduced into the solar wind dynamic pressure time series. In this numerical experiment, the idealized ...

Energy Technology Data Exchange (ETDEWEB)

Three agricultural applications in a specially designed greenhouse solar system functioning as a multi-purpose solar air collector for crop production and curing/drying processes are examined. An automated hydroponic crop production system is proposed for the greenhouse solar system. Design criteria of the proposed system and its utilization of solar energy for root-zone warming are presented and discussed. Based upon limited testing of the hydroponic system considered, hydroponic production of greenhouse crops is believed reasonable to complement the year-round use of the greenhouse solar system. The hardware/software design features of a microcomputer-based control system applied in the greenhouse solar barn are presented and discussed. On-line management and utilization of incident solar energy by the microcomputer system are investigated ...

Energy Technology Data Exchange (ETDEWEB)

The Active Magnetospheric Particle Tracer Explorers (AMPTE) program provided important information on the behavior of clouds of plasma artificially injected into the solar wind and the earth's magnetosphere. Now that the releases are over, data from the satellites are being analyzed to investigate the processes by which the ambient solar wind mass, momentum, and energy are transferred to the magnetosphere. Work in progress at APL indicates that the solar wind is much more inhomogeneous than previously believed, that the solar wind constantly buffets the magnetosphere, and that ground observers may remotely sense these interactions as geomagnetic pulsations. 8 refs.

Energy Technology Data Exchange (ETDEWEB)

The invention concerns a solar power station with a hollow solar heater, which has reflected radiation coming in, focussed by a mirror through the inlet opening. To match the differing solar radiation during the day, the inlet opening can be adjusted by changing its cross-section. This is done by at least two thick flat circular parts which can move relative to each other which are preferably movable relative to each other in pairs on a common rail and which are cooled by a coolant which is the working medium for absorbing solar energy.

Energy Technology Data Exchange (ETDEWEB)

As concern regarding global environmental problems such as the greenhouse effect and acid rain has increased, so too has the demand for commercially viable solar cells as a clean energy source. Interest in amorphous silicon (a-Si) solar cells has been particularly high, due to their low cost. Technological developments in the field of a-Si solar cells are discussed from the viewpoints of fabrication process, materials, and cell structures. Various applications and systems that take advantage of the a-Si solar cell are then introduced. Finally, future prospects are mentioned

Science.gov (United States)

An electric power generating apparatus is described, including: a solar collector; a primary thermal loop including primary thermal fluid; a cavity receiver to receive reflected solar energy from the solar reflector, convert the solar energy into thermal energy, and transmit the thermal energy to the primary thermal fluid by heating the primary thermal fluid not to exceed a given temperature, the given temperature being substantially equal to 700 F; a Stirling engine receiving the primary thermal fluid heated by the cavity receiver, including means to generate mechanical power and means to generate electrical power from the means to generate mechanical power.

Energy Technology Data Exchange (ETDEWEB)

This paper addresses the stability aspects of several successful dc superconducting magnets such as large bubble chamber magnets, and magnets for the Mirror Fusion Test Facility and MHD Research Facility. Specifically, it will cover Argonne National Laboratory 12-Foot Bubble Chamber magnets, the 15-foot Bubble Chamber magnets at Fermi National Laboratory, the MFTF-B Magnet System at Lawrence Livermore National Laboratory, the U-25B Bypass MHD Magnet, and the CFFF Superconducting MHD magnet built by Argonne National Laboratory. All of these magnets are cooled in pool-boiling mode. Magnet design is briefly reviewed. Discussed in detail are the adopted stability critera, analyses of stability and disturbance, stability simulation, and the final results of magnet ...

International Nuclear Information System (INIS)

We investigate the magnetic braking of the core of an axisymmetric cloud whose rotation axis is parallel to the mean direction of the magnetic field. (author).

Energy Technology Data Exchange (ETDEWEB)

The magnetic fluid is a colloidal suspension of magnetite in kerosene, prepared by a low-cost process. Separation is accomplished in an open trough filled with magnetic fluid. A magnetic field is established in the fluid, by energizing an electromagnet having poles on each side of the trough. Due to the design of the magnet poles and air gaps, the magnetic field is strongest at the bottom, about 10,000 oersteds, and uniformly decreases in strength to about 2000 oersteds at the top of the fluid. Therefore, the magnetic field gradient increases with depth. The magnetic force attracts the entire separation medium (magnetic fluid) creating a reaction force of equal magnitude and acting in the opposite direction. This reaction created within a magnetic fluid/magnetic field combination ...

International Nuclear Information System (INIS)

We study the one-phase Stefan problem on a semi-infinite strip x> or =0, with the convective boundary condition -KT/sub x/(0,t) = h[T/sub L/--T(0,t)]. Points of intrest include: a) behavior of the surface temperature T(0,t); b) asymptotic behavior as h#->#infinity; c) uniqueness, and d) bounds on the phase change front and total system energy.

International Nuclear Information System (INIS)

The European Research and Development Program on decay heat removal by natural convection for the European Fast Reactor (EFR) covers the calculational methods and the model experiments performed for code validation. The studies concentrate on important physical effects of the cooling modes within the primary system and the direct reactor cooling circuits and include fundamental tests as well as reactor experiments. (author)

Energy Technology Data Exchange (ETDEWEB)

A passive heat exchange enhancement structure which operates by free convection includes a flat mounting portion having a plurality of integral fins bent outwardly from one side edge thereof. The mounting portion is securable around a stovepipe, to a flat surface or the like for transferring heat from the pipe through the fins to the surrounding air by rotation-enhanced free convection.

Energy Technology Data Exchange (ETDEWEB)

An analysis of trapezoidal profile convective pin fins, with internal heat generation density is presented. The solution of the optimal problem is also given, when either the desired heat dissipation rate or the volume of the pin is specified. The results are presented graphically and in polynomial forms that are particularly useful for computerized calculations. The effect of the fin`s profile and thermal conductivity upon the optimum dimensions is discussed. An example serves to demonstrate the usefulness of the method.

Energy Technology Data Exchange (ETDEWEB)

A solar-powered adsorption air-conditioning system was designed and installed in the green building of Shanghai Research Institute of Building Science. The system contained 150 m{sup 2} solar collectors and two adsorption chillers with nominal refrigeration capacity of 8.5 kW. Based on performance characteristics of the adsorption chiller, the operation mode of the solar-powered air-conditioning system was optimized by maintaining a phase shift of 540 s between the two adsorption chillers. Thereafter, the whole system realized stable operation by the balance of heat consumption and refrigeration output. From June to August of 2005, the solar-powered air-conditioning system continuously ran between 9:00 and 17:00. The operation performance of the system under representative working condition showed that the average refrigeration output of the solar-powered air-conditioning system was ...

International Nuclear Information System (INIS)

Natural convection flow is established in KMRR (Korea Multi-Purpose Research Reactor) reflector tank at the loss of reflector circulator. To simulate the reflector tank natural convection flow with high temperatures at the inner shell and bottom plate due to nuclear heating, experimental and numerical studies in an open cavity with 'L' type heated wall made by the combination of a vertical and horizontal plate were performed. It was confirmed through these studies that the heat transfer rates were highest at the lower region of the vertical plate and the inlet region of horizontal plate and comparatively high at the middle portion of both plates. The heat transfer rate distribution of this trend shows a desirable trend for the effective natural convection cooling of KMRR reflector tank. It was also confirmed that the average Nusselts numbers at the 'L' type heated wall were lower than those obtained from the existing ...

Energy Technology Data Exchange (ETDEWEB)

A stochastic-convective reactive (SCR) transport method is developed for one-dimensional steady transport in physically heterogeneous media with nonlinear degradation. The method is free of perturbation amplitude limitations and circumvents the difficulty of scale dependence of phenomenological parameters by avoiding volume-averaged specifications of diffusive/dispersive fluxes. The transport system is conceptualized as an ensemble of independent convective-reactive streamlines, each characterized by a randomized convective velocity (or travel time). Dispersive effects are treated as a component of the randomness in the streamline velocity ensemble, so no explicit expression for hydrodynamic dispersive flux is written in the streamline transport equation. The expected value of the transport over the stream tube ensemble is obtained as an average of solutions to the reactive convection equation according ...

British Library Electronic Table of Contents (United Kingdom)

An experimental investigation on the thermal decomposition of CH4 into C and H2 was carried out using a 5kW particle-flow solar chemical reactor tested in a solar furnace in the 1300-1600K range. The reactor features a continuous flow of CH4 laden with mm-sized carbon black particles, confined to a cavity receiver and directly exposed to concentrated solar irradiation of up to 1720 suns. The reactor performance was examined for varying operational parameters, namely the solar power input, seed particle volume fraction, gas volume flow rate, and CH4 molar concentration. Methane conversion and hydrogen yield exceeding 95% were obtained at residence times of less than 2.0s. A solar-to-chemical energy conversion efficiency of 16% was experimentally reached, and a maximum value of 31% was numer...

Energy Technology Data Exchange (ETDEWEB)

A laser beam apparatus and method for analyzing, inter alia, the current versus voltage curve at the point of illumination on a solar cell and the open circuit voltage of a solar cell. The apparatus incorporates a lock-in amplifier, and a laser beam light chopper which permits the measurement of the AC current of the solar cell at an applied DC voltage at the position on the solar cell where the cell is illuminated and a feedback scheme which permits the direct scanning measurements of the open circuit voltage. The accuracy of the measurement is a function of the intensity and wavelength of the laser light with respect to the intensity and wavelength distribution of sunlight and the percentage the dark current is at the open circuit voltage to the short circuit current of the solar cell.

Energy Technology Data Exchange (ETDEWEB)

Rare Earth Cobalt (REC) permanent magnets have unique properties that permit solutions to some optical tasks that cannot be accomplished with conventional magnets. A review of design and of performance characteristics of these magnets includes an analytical description of the three dimensional fringe fields of REC quadrupoles.

KoreaScience (Korea)

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KoreaScience (Korea)

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J-STORE (Japan)

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KoreaScience (Korea)

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KoreaScience (Korea)

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Science.gov (United States)

Magnetic Forming Studies. The use of transient high magnetic-field devices has made possible the generation of very large accurately ...

International Nuclear Information System (INIS)

... susceptibility magnetization magnetoresistance monocrystals order-disorder

Science.gov (United States)

... magnetic containment field lines which is zero on the center line of the toroidal containment tube and increases in magnitude with ...

KoreaScience (Korea)

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International Nuclear Information System (INIS)

In order to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices, a symposium was held. The proceedings are presented. The sessions covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems.

Energy Technology Data Exchange (ETDEWEB)

The dwelling is equipped with solar collectors which heat the air circulating in the cavity walls and the space beneath the floors. The thermal aspects of such a building are described. Heat balance, losses, heating by the sun in different seasons are described. Different measures taken to reduce the energy losses are described.

Energy Technology Data Exchange (ETDEWEB)

Forms used in conducting a national survey about solar energy are presented. Forms for representatives from the domestic, commercial, and industrial sectors, owners and non-owners of solar equipment, are shown. Participants were to be contacted by telephone, mail, and personal visits. (MCW)

Energy Technology Data Exchange (ETDEWEB)

Performance and operating characteristics are presented for a solar powered aircraft intended to remain aloft for long periods. The critical technologies which limit the performance are identified. By using the techniques presented, the effects of variation in the system parameters are studied. Practical design consideration are discussed.

Energy Technology Data Exchange (ETDEWEB)

A brief overview of the conceptual design of a solar central receiver system integrated with an existing cogeneration facility is provided. A synopsis of the performance and economic evaluation, and an assessment of the concept from the site owner's perspective are given.

Energy Technology Data Exchange (ETDEWEB)

Conference paper regarding research in freeze-protection methods that could extend market acceptance for passive solar domestic water heating systems in more northern climates if the U.S.

Energy Technology Data Exchange (ETDEWEB)

Topics covered include various aspects of solar cell fabrication and performance. Aluminium-gallium arsenides, cadmium telluride, amorphous silicon, and copper-indium-gallium selenides are all characterized in their applicability in solar cells.

Energy Technology Data Exchange (ETDEWEB)

Laser assisted solar cell metallization processing which is a one step process is examined. The potential advantages of laser disposition techniques for photovoltaic systems are: a high resolution, no photolithography, clean and contamination free, in-situ sintering, and low contact resistance.

Science.gov (United States)

The applicability of isothermal solidification as a contacting method for solar cells was proved for the systems AgSn and AuIn. The process is advantageous in that it requires no fluxes, no inert gases, and no pretreatment of the components. The IE contac...

Science.gov (United States)

Metal-Semiconductor Solar Cells," J. Appl. Phys. 46,. 1286 (1975). 12) H. B. Kim , G. G. Sweeney and I. S. Heng, "Analysis of ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this solar energy project was to design, manufacture, install, maintain and evaluate solar heating systems in order to stimulate community acceptance of the practicality of solar applications, reduce non-renewable energy resource consumption, and decrease residential expenditures for energy. The project also provided skill training and experience for CETA employees in the design, manufacture, and installation of solar energy equipment systems. CDC's contract had four separate solar energy projects; namely: Domestic Water Heating Systems for four Single-Family Homes; Domestic Water Heating for an industrial building; Domestic Water Heating for a (4) unit apartment complex (includes (12) supplemental space heating units); and Integral Passive Water Heaters and Energy Conservation Devices for (8) one bedroom homes. CDC staff designed all ...

Energy Technology Data Exchange (ETDEWEB)

In this report, the main emphasis is given to (1) the problems associated with the basic calibration of the spectroradiometer and (2) the year-to-year variability of the calibrations of the solar UV network radiometers. Also, the results from intercomparisons of the Brewer and OL 742 spectroradiometers are included

Science.gov (United States)

ADVANCED MODELING, S IMULATION, AND ANALYSIS (ROADMAP 14). ...... Metal/Silicon Extraction from Regolith & manufacturing ..... addresses solar power, energy storage (in conjunction with solar power and as a prime source of ...

Energy Technology Data Exchange (ETDEWEB)

A conceptual design of a solar retrofit to US Gypsum's plant at Sweetwater, Texas, has been developed which provides heated air to a large gypsum board drying kiln that is currently under construction. The solar heated air displaces natural gas normally used for the process heat. The solar retrofit is composed of a tower focus collector with a cavity receiver which uses air as the heat transfer fluid. An executive summary of the conceptual design, system performance, economics, and development plan is presented. (WHK)

Energy Technology Data Exchange (ETDEWEB)

Solar heating of gas turbine plants is moving back to the focus of current research. The mainly unsteady operation of solar turbine power plants can only be predicted with sufficient accuracy if the transient behavior of the solar radiation receiver is known. Therefore the transient behavior of cavity receivers of different designs is investigated. The mathematical model used to simulate heat transfer and energy storage is illustrated. Computed results for two receivers with different inner lining are compared and evaluated concerning their use in practice.

Energy Technology Data Exchange (ETDEWEB)

A solar energy receiver is described including a separable endless wall formed of a ceramic material having defined therein a cavity of a substantially cylindrical configuration for entrapping solar flux, and an acceptance aperture adapted to admit to the cavity a concentrated beam of solar energy, said wall being characterized by at least a pair of contiguously related segments separated by lines of cleavage intercepting said aperture, at least one of the segments being supported for pivotal displacement, and a thermal responsive actuator adapted to respond to excessive temperatures within the cavity for initiating pivotal displacement of said one segment, whereby thermal flux is permitted to escape from the cavity.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

British Library Electronic Table of Contents (United Kingdom)

The Monte Carlo ray-tracing method is applied and coupled with optical properties to predict the radiation performance of solar concentrator/cavity receiver systems. Several different cavity geometries are compared on the radiation performance. A flux density distribution measurement system for dish parabolic concentrators is developed. The contours of the flux distribution for target placements at different distances from the dish vertex of a solar concentrator are taken by using an indirect method with a Lambert and a charge coupled device (CCD) camera. Further, the measured flux distributions are compared with a Monte Carlo-predicted distribution. The results can be a valuable reference for the design and assemblage of the solar collector system.

Science.gov (United States)

MILSTAR's Flexible Substrate Solar Array (FSSA) is an evolutionary development of the lightweight, flexible substrate design pioneered at Lockheed during the seventies. Many of the features of the design are related to the Solar Array Flight Experiment (SAFE), flown on STS-41D in 1984. FSSA development has created a substantial technology base for future flexible substrate solar arrays such as the array for the Space Station Freedom. Lessons learned during the development of the FSSA can and should be applied to the Freedom array and other future flexible substrate designs.

Energy Technology Data Exchange (ETDEWEB)

Laser-assisted processing techniques for producing high-quality solar cell metallization patterns are investigated, developed, and characterized. The tasks comprising these investigations are outlined. A new batch of solar cells was processed using the laser decomposition of spun-on silver neodecanoate to metallize cells. Decomposition of silver neodecanoate was carried out at different laser powers on different cells on a given wafer to determine whether this would have any effect on cell performance. Solar cells which were written with laser powers of 5 to 8 watts, gave excellent results with cell efficiencies in the range of 14 to 16%.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

The performance of a solar chemical heat pipe was studied using CO{sub 2}reforming of methane as the endothermic reaction. A directly heated vertical reactor, packed with a rhodium catalyst was used. The solar tests were carried out in the Schaeffer solar furnace of the Weizmann Institute of Science. The power absorbed was up to 6.3 KW, the maximal flow rates of the gases reached 11,000 1/h, and the methane conversions reached 85%. A computer model was developed to simulate the process. Agreement of the calculations with the experimental results was quite satisfactory.

Energy Technology Data Exchange (ETDEWEB)

This proceedings volume contains contributions by about 70 authors on market trends, funding, marketing, boundary conditions and sales promotion of thermal solar energy and photovoltaic systems. The contributions reflect the diversity of authors, e.g. consultants, advocates and agents of solar technology producers and financial organisations. Central issues were markets in and outside Europe, quality assurance, interdepartmental cooperations, and marketing strategies of the solar industry. The proceedings volume also contains the conference schedule and self-descriptions of the authors' institutions. (orig.)

International Nuclear Information System (INIS)

A non-contact method, using magnetic drag force principle, was proposed to design the braking systems to improve the shortcomings of the conventional braking systems. The extensive literature detailing all aspects of the magnetic braking is briefly reviewed, however little of this refers specifically to upright magnetic braking system, which is useful for industries. One of the major issues to design upright magnetic system is to find out the magnetic flux. The changing magnetic flux induces eddy currents in the conductor. These currents dissipate energy in the conductor and generate drag force to slow down the motion. Therefore, a finite element model is developed to analyze the phenomena of magnetic flux density when air gap and materials of track are varied. The verification shows the predicted magnetic flux is within ...

Energy Technology Data Exchange (ETDEWEB)

Presented are some preliminary studies made in preparation for the design of a solar powered loop for desalination by humidification - dehumidification process. The studies concentrated on the evaluation of different parameters affecting the performance of the combination of different components in such a loop in the hope of outlining the most decisive factors for the choice or design of solar collectors or heat source. The results presented relate to the performance of two of the most important components in a loop of such purpose, that is: the humidifying and the dehumidifying columns or stacks. 4 refs.

Energy Technology Data Exchange (ETDEWEB)

Literature summarizing a study on the Saudi Arabian solar controlled environment agriculture system is presented. Specifications and performance requirements for the system components are revealed. Detailed performance and cost analyses are used to determine the optimum design. A preliminary design of an engineering field test is included. Some weather data are provided for Riyadh, Saudi Arabia. (BCS)

Energy Technology Data Exchange (ETDEWEB)

The results of tests performed on the FMC Fresnel-Belt Solar Collector at the Midtemperature Solar Systems Test Facility are summarized. Tests were conducted over a temperature range from 100 to 250/sup 0/C. Test objectives are defined, test procedures are described, and test results and conclusions are given.

Energy Technology Data Exchange (ETDEWEB)

Investigation of selective emitter solar cells has been undertaken using both device fabrication and accurate two-dimensional simulation program. Our results show that selective emitter solar cells exhibit a relatively low fill factor because of minority carriers crowding at the lateral junction. It is also found that carrier recombination in the space-charge region of the lateral junction limits open-circuit voltage improvements

Energy Technology Data Exchange (ETDEWEB)

Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed.

British Library Electronic Table of Contents (United Kingdom)

This paper looks at the various battery technologies available for use in solar assist plug-in hybrid electric tractors In this context, solar assist plug-in hybrid electric tractors are those that may be used in light-duty agricultural operations. To determine the most suitable battery, four common technologies are analyzed looking at the environmental life-cycle effects and costs.

Energy Technology Data Exchange (ETDEWEB)

The Detartment of Energy's National Solar Data Program established solar energy systems in residential and commercial buildings across the United States. These solar sites are linked to Vitro Laboratories Division's computer in the National Solar Data Network (NSDN). Vitro collects and analyzes data from this network to determine the thermal performance of each of the solar systems. Environmental information collected at the sites for the month of August 1980 is presented. The environmental data for the NSDN are presented in the form of tables for each solar site. The solar sites are grouped into 12 zones, each of which consists of several adjacent states. The solar energy sites are in alphabetical sequence within each zone. The tables provide available meteorological data for reporting sites in the ...

Energy Technology Data Exchange (ETDEWEB)

The mainly instationary operation of a solar heated receiver can be simulated with sufficient accuracy only if data about the dynamic behavior are available. For this reason, the dynamic behavior of a solar cavity receiver with parabolic dish collector is investigated. The development of a mathematical simulation considering heat transfer and storage processes is presented and the procedure for a numerical solution is illustrated. The performance of the calculation method is finally demonstrated by simulating the passage of a cloud.

Energy Technology Data Exchange (ETDEWEB)

Installation of the electrical equipment at the Barstow Solar Pilot Plant is the concern of this construction package. Technical specifications for power and instrument cables, meteorological instruments, and control cables are defined. The documentation requirements are briefly discussed.

International Nuclear Information System (INIS)

The stability of a couple stress fluid saturated horizontal porous layer heated from below and cooled from above when the fluid and solid phases are not in local thermal equilibrium is investigated. The Darcy model is used for the momentum equation and a two-field model is used for energy equation each representing the solid and fluid phases separately. The linear stability theory is employed to obtain the condition for the onset of convection. The effect of thermal non-equilibrium on the onset of convection is discussed. It is shown that the results of the thermal non-equilibrium Darcy model for the Newtonian fluid case can be recovered in the limit as couple stress parameter C?0. We also present asymptotic analysis for both small and large values of the inter phase heat transfer coefficient H. We found an excellent agreement between the exact solutions and asymptotic solutions when H is very small.

International Nuclear Information System (INIS)

The roughness length at air-sea interface during free convection (Z0fc) is mainly related to the convective velocity (w) rather than the friction velocity (u). The parameterization of Z0fc with (w)2/g as proposed by Abdella and D'Alessio (2003) is evaluated. It is shown that the field measurements at MM Lab, Tarapur Maharashtra Site (TMS) coastal site using Metek GmbH, Ultra sonic anemometers are consistent with the proposed formula. In order to avoid self-correlation by using u, a new parameterization of w with ?u and ?v and gustiness parameter as given by Fairall et al. (1996) is used. The mean values of w and Z0fc estimated using new parameterization were observed to be 0.97 m/s and 2.3E-4 m respectively for the year 2009 at TMS. (author)

International Nuclear Information System (INIS)

The recognition that natural convection offers the prospect of an important inherent safety feature for liquid metal cooled reactor systems has provided the impetus for a world-wide research effort over the past decade. Whilst this research has been based on experiment, both plant experiments and out-of-pile experiments, the enormous advances in the development of computing power in recent years have enabled complementary programmes of mathematical modelling through numerical simulation of the transport equations in three spatial dimensions. These not only offer considerable promise for the designer in projecting the behaviour from experiments and prototype plant to full scale plant, they have also proved to be of considerable value in helping us to interpret and understand the results of the experiments themselves. This paper attempts to review the progress made with the emphasis on decay heat removal by natural convection in the pool-type ...

British Library Electronic Table of Contents (United Kingdom)

An experimental study was performed to investigate the heat transfer characteristics of the mixed convection flow through a horizontal rectangular channel where open-cell metal foams of different pore densities (10, 20 and 30 PPI) were situated. A uniform heat flux was applied at all of the bounding walls of the channel. For each of three values of the uniform heat flux, temperatures were measured on the entire surfaces of the walls. Results for the average and local Nusselt numbers are presented as functions of the Reynolds and Richardson numbers. The Reynolds number based on the channel height of the rectangular channel was varied from 600 to 33000, while the Richardson number ranged from 0.02 to 103, extending over forced, mixed and natural convection. Second important parameter that in...

Energy Technology Data Exchange (ETDEWEB)

As a method to make use of a high latent heat of a liquid-solid phase change material in a confined convective heat transfer, a phase change material, lauric acid, was encapsulated in a tiny hollow sphere, and mixed with water, forming a slurry of microencapsulated phase-change material (MCPCM slurry). Four different sizes (200, 100, 50, and 25 {mu}m ID) of MCPCMs were tested in this study. Thermal characteristics of the pure lauric acid and lauric acid MCPCMs were tested by a differential scanning calorimeter. Viscosity of the slurries of water and the capsules was measured by a rotating viscometer. The slurries were also tested in a convective-heat-transfer-test apparatus. (author). 11 refs., 5 figs., 1 tab.

International Nuclear Information System (INIS)

To investigate the magnetic fluctuations and for further transport study, the poloidal and radial magnetic field measurement is conducted on the Sino United Spherical Tokamak (SUNIST). Auto-power spectral density indicates that the magnetic fluctuation energy mainly concentrates in the frequency region lower than 10 kHz. The magnetic field oscillations, which are characterized by harmonic frequencies of 40 kHz, are observed in the scrape-off layer; by contrast, in the plasma core, the magnetic fluctuations are of Gaussian type. The time-frequency profiles show that the poloidal magnetic fluctuations are temporally intermittent. The autocorrelation calculation indicates that the fluctuations in decorrelation time vary between the core and the edge. (authors)

British Library Electronic Table of Contents (United Kingdom)

Solar cavity receiver plays a dominant role in the light-heat conversion. Its performance can directly affect the efficiency of the whole power generation system. A combined calculation method for evaluating the thermal performance of the solar cavity receiver is raised in this paper. This method couples the Monte-Carlo method, the correlations of the flow boiling heat transfer, and the calculation of air flow field. And this method can ultimately figure out the surface heat flux inside the cavity, the wall temperature of the boiling tubes, and the heat loss of the solar receiver with an iterative solution. With this method, the thermal performance of a solar cavity receiver, a saturated steam receiver, is simulated under different wind environments. The highest wall temperature of the boi...

British Library Electronic Table of Contents (United Kingdom)

In the last years, the growing demand for air conditioning has caused a significant increase in demand for primary energy resources. Solar-powered cooling is one of the technologies which allows to obtain, by using the renewable solar source, an important energy saving compared to traditional air conditioning plants. The paper describes different technical installations for solar cooling, their way of operation, advantages and limits. The objective of the present study has been to analyze the technical and economic feasibility of solar absorption cooling systems, designed for two different application fields: industrial refrigeration and air conditioning. The possibility to replace or integrate the existing plants is studied, by considering the refrigeration requirements of a company, whic...

Energy Technology Data Exchange (ETDEWEB)

For a solar cell, in order to minimize the loss of incident light, transparent glass or plastic material is used at the incident part. When a solar cell is watched from the light incident part, a silicon base material is directly observed with either block or brown color only. This invention enables a solar cell to give brighter color on the incident surface by placing a reflective film which reflects only the light of specific wavelength, without reducing the efficiency of the solar cell. This reflective film consists of multi-layered dielectric with 12 layers and alternative combination of highly refractive and less refractive substances. Highly refractive layer is Y/sub 2/O/sub 3/ with refractive index 1.74 and the less refractive layer is SiO/sub 2/ with refractive index 1.45. (5 figs)

Energy Technology Data Exchange (ETDEWEB)

This is a process for manufacturing a semi-rigid, folding solar generator manufactured from several coated solar cells (Cics), which has at least two folding parts connected together so as to turn by hinges, characterized by the following stages of the process: a) On the back of matrix subsections, in order to cover the connector, carbon fibre strips are glued on, which project over the upper or lower edge of each matrix subsection. b) The projecting ends of adjacent carbon fiber strips are connected with two carbon fibre strips. c) At least two matrix subsections are fixed in separately manufactured carbon fiber frames, and d) the carbon fiber frames, together with the matrix subsections are connected via hinges to a solar generator.

Science.gov (United States)

A glass heat pipe is adapted for use as a solar energy absorber in an evacuated tube solar collector and for transferring the absorbed solar energy to a working fluid medium or heat sink for storage or practical use. A capillary wick is formed of granular glass particles fused together by heat on the inside surface of the heat pipe with a water glass binder solution to enhance capillary drive distribution of the thermal transfer fluid in the heat pipe throughout the entire inside surface of the evaporator portion of the heat pipe. Selective coatings are used on the heat pipe surface to maximize solar absorption and minimize energy radiation, and the glass wick can alternatively be fabricated with granular particles of black glass or obsidian.

Energy Technology Data Exchange (ETDEWEB)

Unmanned Aerial Vehicles (UAV) are being proposed for many applications including surveillance, mapping and atmospheric studies. These applications require a lightweight, low speed, medium to long duration airplane. Due to the weight, speed, and altitude constraints imposed on such aircraft, solar array generated electric power is a viable alternative to air-breathing engines. Development of such aircraft is currently being funded under the Environmental Research Aircraft and Sensor Technology (ERAST) program. NASA Lewis Research Center (LeRC) is currently building a Solar Electric Airplane to demonstrate UAV technology. This aircraft utilizes high efficiency Applied Solar Energy Corporation (ASEC) GaAs/Ge space solar cells. The cells have been provided by the Air Force through the ManTech Office. Expected completion of the plane is early 1995, with the airplane currently undergoing flight testing using ...

Energy Technology Data Exchange (ETDEWEB)

The field of micro unmanned aerial vehicles ({mu}UAVs) has advanced rapidly in recent years. This paper studies the design and construction of a small solar-powered aircraft near the size range of current {theta}UAVs. A number of aspects of their design were analysed, including structural, aerodynamic and propulsion system considerations. The effect of small-scale, low Reynolds number aerodynamics was investigated, and the performance of a range of candidate aerofoils was compared. The integration of a solar power source into the aircraft system was considered a key design issue. Consequently, a number of aircraft configurations were examined, with the intention of optimising the application of solar power in a miniature aircraft. Investigation of improved system components suggests that a practical solar-powered aircraft in the size range below 500 mm maximum linear dimension should be viable given ...

British Library Electronic Table of Contents (United Kingdom)

This paper presents a hybrid solar desalination process of the multi-effect humidification dehumidification and the basin-type unit. The sketch of the hybrid solar desalination process is given. The solar vacuated tube collector is employed in the desalination system, multi-effect humidification dehumidification desalination (HDD) process is plotted according to pinch technology, and then the water rejected from multi-effect HDD process is reused to desalinate in a basin-type unit further. The gain output ratio (GOR) of this system will rise by 2?3 at least through reusing the rejected water. The research proves that the multi-effect HDD has much room to be improved. A hybrid solar desalination process of the multi-effect humidification dehumidification and the basin-type unit should be no...

Energy Technology Data Exchange (ETDEWEB)

Onset of convection in a layer of couple-stress fluid-saturated porous medium is investigated for different types of basic temperature gradients. The boundaries are considered to be adiabatically insulated to temperature perturbations. The eigenvalue equations of the perturbed state obtained from the normal mode analysis are solved analytically using a regular perturbation technique with wave number as a perturbation parameter and also numerically using the Galerkin technique. The critical stability parameters obtained from these two techniques are in excellent agreement and an increase in the value of couple-stress parameter is found to delay the onset of convection. The results also indicate that the piecewise linear temperature profile hastens the onset of convection when compared to linear, parabolic, and inverted parabolic temperature profiles. In addition, the influence of thermal depth on the critical conditions is ...

International Nuclear Information System (INIS)

A disk formation model during collapse of the protosolar nebula, yielding a low-mass protoplanetary disk is presented. The following subject areas are covered: (1) circumstellar disks; (2) conditions for the formation of stars with disks; (3) early evolution of the protoplanetary disk; and (4) temperature conditions and the convection in the protoplanetary disk.

Science.gov (United States)

Scraped-surface heat transfer augmentation is proposed as a possible technique for use in improved air-cooling designs. Although it has been in common use with liquids, the technique has apparently never been used with gases. An experimental investigation...

UK PubMed Central (United Kingdom)

BackgroundBlood sampling through heel lancing is the most common invasive painful procedure performed on newborn infants.Case PresentationWe report...Full Text Available