WorldWideScience
1

Radiant energy collector  

Science.gov (United States)

A cylindrical radiant energy collector is provided which includes a reflector spaced apart from an energy absorber. The reflector is of a particular shape which ideally eliminates gap losses. The reflector includes a plurality of adjacent facets of V shaped segments sloped so as to reflect all energy entering between said absorber and said reflector onto said absorber. The outer arms of each facet are sloped to reflect one type of extremal ray in a line substantially tangent to the lowermost extremity of the energy absorber. The inner arms of the facets are sloped to reflect onto the absorber all rays either falling directly thereon or as a result of reflection from an outer arm.

McIntire, William R. (Downers Grove, IL)

1983-01-01

2

Nonimaging radiant energy device  

Science.gov (United States)

A nonimaging radiant energy device may include a hyperbolically shaped reflective element with a radiant energy inlet and a radiant energy outlet. A convex lens is provided at the radiant energy inlet and a concave lens is provided at the radiant energy outlet. Due to the provision of the lenses and the shape of the walls of the reflective element, the radiant energy incident at the radiant energy inlet within a predetermined angle of acceptance is emitted from the radiant energy outlet exclusively within an acute exit angle. In another embodiment, the radiant energy device may include two interconnected hyperbolically shaped reflective elements with a respective convex lens being provided at each aperture of the device.

Winston, Roland (Chicago, IL); Ning, Xiaohui (North Providence, RI)

1996-01-01

3

Multiscale computational modeling of a radiantly driven solar thermal collector  

Science.gov (United States)

The objectives of the master's thesis are to present, discuss and apply sequential multiscale modeling that combines analytical, numerical (finite element-based) and computational fluid dynamic (CFD) analysis to assist in the development of a radiantly driven macroscale solar thermal collector for energy harvesting. The solar thermal collector is a novel green energy system that converts solar energy to heat and utilizes dry air as a working heat transfer fluid (HTF). This energy system has important advantages over competitive technologies: it is self-contained (no energy sources are needed), there are no moving parts, no oil or supplementary fluids are needed and it is environmentally friendly since it is powered by solar radiation. This work focuses on the development of multi-physics and multiscale models for predicting the performance of the solar thermal collector. Model construction and validation is organized around three distinct and complementary levels. The first level involves an analytical analysis of the thermal transpiration phenomenon and models for predicting the associated mass flow pumping that occurs in an aerogel membrane in the presence of a large thermal gradient. Within the aerogel, a combination of convection, conduction and radiation occurs simultaneously in a domain where the pore size is comparable to the mean free path of the gas molecules. CFD modeling of thermal transpiration is not possible because all the available commercial CFD codes solve the Navier Stokes equations only for continuum flow, which is based on the assumption that the net molecular mass diffusion is zero. However, thermal transpiration occurs in a flow regime where a non-zero net molecular mass diffusion exists. Thus these effects are modeled by using Sharipov's [2] analytical expression for gas flow characterized by high Knudsen number. The second level uses a detailed CFD model solving Navier Stokes equations for momentum, heat and mass transfer in the various components of the device. We have used state-of-the-art computational fluid dynamics (CFD) software, Flow3D (www.flow3d.com) to model the effects of multiple coupled physical processes including buoyancy driven flow from local temperature differences within the plenums, fluid-solid momentum and heat transfer, and coupled radiation exchange between the aerogel, top glazing and environment. In addition, the CFD models include both convection and radiation exchange between the top glazing and the environment. Transient and steady-state thermal models have been constructed using COMSOL Multiphysics. The third level consists of a lumped-element system model, which enables rapid parametric analysis and helps to develop an understanding of the system behavior; the mathematical models developed and multiple CFD simulations studies focus on simultaneous solution of heat, momentum, mass and gas volume fraction balances and succeed in accurate state variable distributions confirmed by experimental measurements.

Ponnuru, Koushik

4

Radiant Energy Flow  

Science.gov (United States)

How does energy flow in and out of our atmosphere? Explore how solar and infrared radiation enters and exits the atmosphere with an interactive model. Control the amounts of carbon dioxide and clouds present in the model and learn how these factors can influence global temperature. Record results using snapshots of the model in the virtual lab notebook where you can annotate your observations.

The Concord Consortium

2011-12-11

5

Clouds and the Earth's Radiant Energy System  

Science.gov (United States)

The Clouds and the Earth's Radiant Energy System (CERES) instrument is one of five instruments that will be flown aboard the Tropical Rainfall Measuring Mission (TRMM) observatory. Data from the CERES instrument will be used to study the energy exchanged between the Sun and the Earth's atmosphere, surface and clouds, and space. This webpage describes the TRMM mission, the CERES insrument, and how Earth's daily weather and climate are controlled by the balance between the amount of solar energy received by the Earth (both by its surface and its atmosphere and clouds) and the amount of energy emitted by Earth into space. School children worldwide will be involved in the CERES program, enabling them to be part of a scientific project. As a CERES instrument passes over, students will make local observations to determine the types of clouds over their school, the clouds' altitudes and how much of the sky they cover. Via the Internet, the students will then place their data in the NASA Langley Distributed Active Archive Center where the data will be stored for further analysis by the CERES science team.

6

Thin film solar energy collector  

Science.gov (United States)

A multi-layer solar energy collector of improved stability comprising: (1) a substrate of quartz, silicate glass, stainless steel or aluminum-containing ferritic alloy; (2) a solar absorptive layer comprising silver, copper oxide, rhodium/rhodium oxide and 0-15% by weight of platinum; (3) an interlayer comprising silver or silver/platinum; and (4) an optional external anti-reflective coating, plus a method for preparing a thermally stable multi-layered solar collector, in which the absorptive layer is undercoated with a thin film of silver or silver/platinum to obtain an improved conductor-dielectric tandem.

Aykan, Kamran (Monmouth Beach, NJ); Farrauto, Robert J. (Westfield, NJ); Jefferson, Clinton F. (Millburn, NJ); Lanam, Richard D. (Westfield, NJ)

1983-11-22

7

Radiant Barriers Save Energy in Buildings  

Science.gov (United States)

Langley Research Center needed to coat the Echo 1 satellite with a fine mist of vaporized metal, and collaborated with industry to create "radiant barrier technology." In 2010, Ryan Garrett learned about a new version of the technology resistant to oxidation and founded RadiaSource in Ogden, Utah, to provide the NASA-derived technology for applications in homes, warehouses, gymnasiums, and agricultural settings.

2014-01-01

8

Radiant transfer in gas filled enclosures by radiant energy absorption distribution method  

International Nuclear Information System (INIS)

A radiant heat ray method is employed to determine the radiant energy absorption distribution in a nonisothermal enclosure filled with nonisothermal gas. This method eliminates the complexity of the zoning method in calculating the surface-surface, gas-gas and gas-surface direct exchange areas. It can also deal with the nonuniformity of the gas absorption coefficient and wall emissivity. A study on radiation in a cylindrical enclosure reveals that the radiant heat ray method requires less computation time and yields more accurate results than the Monte Carlo method in determining the absorption distribution. A combined method is developed which utilizes the absorption distribution as the data base for predicting the distributions of temperature and heat flux within an enclosure. The applications of this method are demonstrated by two systems: a continuous heating furnace and a marine boiler furnace. Theory is in good agreement with the field tests. The ultimate goal of the absorption method is to diagnose the enclosure radiation characteristics to find a means for homogenizing the surface heat transfer

9

CERES: Clouds and the Earth's Radiant Energy System  

Science.gov (United States)

This brochure gives a brief description of the science research that is being done with data from the Clouds and Earth's Radiant Energy System (CERES) instrument flying onboard NASA's Terra satellite. It also contains information about some of the data products and technical specifications.

10

Two-dimensional radiant energy array computers and computing devices  

Science.gov (United States)

Two dimensional digital computers and computer devices operate in parallel on rectangular arrays of digital radiant energy optical signal elements which are arranged in ordered rows and columns. Logic gate devices receive two input arrays and provide an output array having digital states dependent only on the digital states of the signal elements of the two input arrays at corresponding row and column positions. The logic devices include an array of photoconductors responsive to at least one of the input arrays for either selectively accelerating electrons to a phosphor output surface, applying potentials to an electroluminescent output layer, exciting an array of discrete radiant energy sources, or exciting a liquid crystal to influence crystal transparency or reflectivity.

Schaefer, D. H.; Strong, J. P., III (inventors)

1976-01-01

11

''Super-radiant'' states in intermediate energy nuclear physics  

International Nuclear Information System (INIS)

A ''super-radiant'' state emerges when, under certain conditions, one or a few ''internal'' states acquire a large collective decay width due to the coupling to one or a few ''external'' decay channels. The rest of the internal states are ''stripped'' of their decay width and become long lived quasistationary states. The essentials of such mechanism and its possible role in intermediate energy nuclear physics are discussed in this work

12

Radiant energy collection and conversion apparatus and method  

Science.gov (United States)

The apparatus for collecting radiant energy and converting same to alternate energy form includes a housing having an interior space and a radiation transparent window allowing, for example, solar radiation to be received in the interior space of the housing. Means are provided for passing a stream of fluid past said window and for injecting radiation absorbent particles in said fluid stream. The particles absorb the radiation and because of their very large surface area, quickly release the heat to the surrounding fluid stream. The fluid stream particle mixture is heated until the particles vaporize. The fluid stream is then allowed to expand in, for example, a gas turbine to produce mechanical energy. In an aspect of the present invention properly sized particles need not be vaporized prior to the entrance of the fluid stream into the turbine, as the particles will not damage the turbine blades. In yet another aspect of the invention, conventional fuel injectors are provided to inject fuel into the fluid stream to maintain the proper temperature and pressure of the fluid stream should the source of radiant energy be interrupted. In yet another aspect of the invention, an apparatus is provided which includes means for providing a hot fluid stream having hot particles disbursed therein which can radiate energy, means for providing a cooler fluid stream having cooler particles disbursed therein, which particles can absorb radiant energy and means for passing the hot fluid stream adjacent the cooler fluid stream to warm the cooler fluid and cooler particles by the radiation from the hot fluid and hot particles.

Hunt, Arlon J. (Oakland, CA)

1982-01-01

13

Effect of radiant energy on near-surface water.  

Science.gov (United States)

While recent research on interfacial water has focused mainly on the few interfacial layers adjacent to the solid boundary, century-old studies have extensively shown that macroscopic domains of liquids near interfaces acquire features different from the bulk. Interest in these long-range effects has been rekindled by recent observations showing that colloidal and molecular solutes are excluded from extensive regions next to many hydrophilic surfaces [Zheng and Pollack Phys. Rev. E 2003, 68, 031408]. Studies of these aqueous "exclusion zones" reveal a more ordered phase than bulk water, with local charge separation between the exclusion zones and the regions beyond [Zheng et al. Colloid Interface Sci. 2006, 127, 19; Zheng and Pollack Water and the Cell: Solute exclusion and potential distribution near hydrophilic surfaces; Springer: Netherlands, 2006; pp 165-174], here confirmed using pH measurements. The main question, however, is where the energy for building these charged, low-entropy zones might come from. It is shown that radiant energy profoundly expands these zones in a reversible, wavelength-dependent manner. It appears that incident radiant energy may be stored in the water as entropy loss and charge separation. PMID:19827846

Chai, Binghua; Yoo, Hyok; Pollack, Gerald H

2009-10-22

14

Wide-angle sensor measures radiant heat energy in corrosive atmospheres  

Science.gov (United States)

Ellipsoidal cavity device measures radiant heat energy over wide incident angles in corrosive atmospheres. The instrument consists of a cavity in copper heat sink sealed with sapphire window to protect thermocouple.

1965-01-01

15

Evaluation of the interaction with radiant energy of substances traversed by a bore hole  

International Nuclear Information System (INIS)

Disclosed is a well logging method and apparatus for obtaining impulse response of a formation traversed by a bore hole by means of correlation techniques. Use is made of a source of radiant energy and of a control element for said source to produce a substantially random or pseudorandom sequence of discrete bursts of radiant energy from the source to cause interactions of these bursts with the formation whereby characteristic radiations of interactions are produced. A detector is provided which is responsive to these radiations to produce corresponding signals. In one embodiment of my invention the impulse response, expressed by a function h(T), is obtained by crosscorrelating signals produced by the detector with signals representing the bursts of radiant energy from the source. In another embodiment the impulse response h(T) of the formation is obtained by autocorrelating signals produced by the detector. In another embodiment of my invention the outputs of two detectors, differently spaced from a source of radiant energy, are crosscorrelated. Using the function h(T), valuable information regarding physical properties of the formation may be obtained. The source of radiant energy may be a source of energetic neutrons, particularly of the deuteriumtritium type, or a source of gamma radiation or of microwaves, or a source of any other form of radiant energy

16

Attic concentrator type solar energy collector  

Energy Technology Data Exchange (ETDEWEB)

Inexpensive tested features of several solar energy collectors have been combined to produce an efficient low cost system. Reflector surfaces supported on metal reinforced corrugated paper redirect and concentrate solar radiation upon an inexpensive shallow pond type receiver formed by a simple wooden frame and a plastic liner. The attic with a greenhouse type south facing side forms a wind screen for the concentrator assembly permitting the use of these light weight structures. Component cost and performance estimates are given.

Cottingham, J. G.

1976-02-04

17

Porous radiant burners having increased radiant output  

Science.gov (United States)

Means and methods for enhancing the output of radiant energy from a porous radiant burner by minimizing the scattering and increasing the adsorption, and thus emission of such energy by the use of randomly dispersed ceramic fibers of sub-micron diameter in the fabrication of ceramic fiber matrix burners and for use therein.

Tong, Timothy W. (Tempe, AZ); Sathe, Sanjeev B. (Tempe, AZ); Peck, Robert E. (Tempe, AZ)

1990-01-01

18

Adaptive control of solar energy collector systems  

CERN Document Server

This book describes methods for adaptive control of distributed-collector solar fields: plants that collect solar energy and deliver it in thermal form. Controller design methods are presented that can overcome difficulties found in these type of plants:they are distributed-parameter systems, i.e., systems with dynamics that depend on space as well as time;their dynamics is nonlinear, with a bilinear structure;there is a significant level of uncertainty in plant knowledge.Adaptive methods form the focus of the text because of the degree of uncertainty in the knowledge of plant dynamics. Parts

Lemos, João M; Igreja, José M

2014-01-01

19

Bulb-type solar energy collector  

Energy Technology Data Exchange (ETDEWEB)

The disclosure relates to a bulb-type solar energy collector device comprising a hollow glass body shaped with a parabolic interior surface that is coated with specular finish of a metal, e.g., silver, and includes an apex aperture and integral hollow yoke. A hollow glass, bulb-shaped absorber element is exteriorly coated with a wave length selective coating. The bulb-shaped element includes a tubular hollow stem dependent from the bulbar portion and fixed in the yoke of the glass body so that the central axis of the stem and bulbar end portion is along the focal axis of the parabolic reflecting surface. A cover plate is sealed over the enlarged end of the reflecting surface enclosing the interior mirror surface in a chamber which is evacuated to substantial vacuum, e.g., 10/sup -4/ torr or greater vacuum. A working media is circulated from a source in a manifold through the interior volume of the absorber element to remove the solar energy absorbed thereby as heat and the media is returned to the manifold. The solar energy laden media is available for heating, cooling or power generating uses.

Pei, Y.K.

1977-09-20

20

Molecules, Water, and Radiant Energy: New Clues for the Origin of Life  

OpenAIRE

We here examine the putative first step in the origin of life: the coalescence of dispersed molecules into a more condensed, organized state. Fresh evidence implies that the driving energy for this coalescence may come in a manner more direct than previously thought. The sun’s radiant energy separates charge in water, and this free charge demonstrably induces condensation. This condensation mechanism puts water as a central protagonist in life rather than as an incidental participant, and t...

Qing Zhao; Pollack, Gerald H.; Xavier Figueroa

2009-01-01

21

Molecules, water, and radiant energy: new clues for the origin of life.  

Science.gov (United States)

We here examine the putative first step in the origin of life: the coalescence of dispersed molecules into a more condensed, organized state. Fresh evidence implies that the driving energy for this coalescence may come in a manner more direct than previously thought. The sun's radiant energy separates charge in water, and this free charge demonstrably induces condensation. This condensation mechanism puts water as a central protagonist in life rather than as an incidental participant, and thereby helps explain why life requires water. PMID:19468316

Pollack, Gerald H; Figueroa, Xavier; Zhao, Qing

2009-04-01

22

Molecules, Water, and Radiant Energy: New Clues for the Origin of Life  

Directory of Open Access Journals (Sweden)

Full Text Available We here examine the putative first step in the origin of life: the coalescence of dispersed molecules into a more condensed, organized state. Fresh evidence implies that the driving energy for this coalescence may come in a manner more direct than previously thought. The sun’s radiant energy separates charge in water, and this free charge demonstrably induces condensation. This condensation mechanism puts water as a central protagonist in life rather than as an incidental participant, and thereby helps explain why life requires water.

Qing Zhao

2009-03-01

23

Proof of concept modeling of energy transfer mechanisms for radiant conditioning panels  

International Nuclear Information System (INIS)

Energy transfer by radiation decouples the heat transfer mechanisms from the ventilation function of the building air without sacrificing the thermal comfort of the occupants. The decoupling is responsible for the higher energy efficiency achieved when radiant cooling and heating systems are utilized. While empirical relations and experimental testing have been introduced by the literature, an analytical methodology that includes the necessary parameters needed for studying the energy transfer mechanisms is desirable. The objective of this study is to present a proof-of-concept formulation and procedure for modeling the heat transfer mechanisms of radiant conditioning panels with considerations for the occupant in a thermal zone. A literature review is conducted to identify the key parameters that affect the performance of the conditioning panels, and then, a proof of concept model is developed so that the performance of the conditioning panels can be analyzed. Using parameters with typical values, for a conventional size room as a thermal zone containing a window and an occupant, the thermal performance of a ceiling mounted conditioning panel is evaluated. Results from the model show that for a ceiling panel at 288.6 K in a 3 m x 3 m x 3 m thermal zone with an ambient temperature of 296.9 K, a 3 m x 2.5 m window and an occupant modeled as a sphere, the total energy flux for the panel is approximately 93.5 W/m2, which is 1.7% higher than that predicted by ach is 1.7% higher than that predicted by an existing empirical relation. It is concluded that the proposed analytical approach is effective as the findings from the model are in agreement with data available from the literature. The model could be used to examine other conditions for the radiant panel

24

RADIANT Research  

Science.gov (United States)

R24 and Development in Advanced Network Technology (RADIANT) is a computer research division of the Los Alamos National Laboratory. The first Web site offers many publications from the five research focus groups within RADIANT: High-Performance Networking, Monitoring and Measurement, Cyber Security, Network Architecture, and Robust Systems and Networks. This material is mostly beneficial to professionals and research students specializing in these areas. The site also has links to information about job opportunities available at RADIANT, as well as the Advanced Summer Curriculum for Emerging Network Technologies (ASCENT). ASCENT is a summer internship program that accepts both undergraduate and graduate students interested in networking research.

25

Bi-radiant oven: a low-energy oven system. Volume I. Development and assessment  

Energy Technology Data Exchange (ETDEWEB)

The Bi-Radiant Oven system has three important features which provide improved performance. First, the cavity walls are highly reflective rather than absorptive thereby allowing these surfaces to operate at cooler temperatures. Second, the heating elements, similar in construction to those in a conventional oven, but operating at much lower temperatures, provide a prescribed, balanced radiant flux to the top and bottom surfaces of the food product. And third, the baking and roasting utensil has a highly absorptive finish. Instrumentation and methods of measurements have been developed for obtaining the important oven and food parameters during baking: wall, oven air, food and element temperatures; food mass loss rate; irradiance distribution; and convection heat flux. Observations on an experimental oven are presented and discussed. Thermal models relating the irradiance distribution to oven parameters have been compared with measurements using a new heat flux gage developed for the project. Using the DOE recommended test procedures, oven efficiencies of 20 to 23% have been measured. The heating requirements have been determined for seven food types: biscuits, meat loaf, baked foods, apple crisp, cornbread, macaroni and cheese casserole, and cheese souffle. Comparison of energy use with a conventional electric oven shows that energy savings greater than 50% can be realized. Detailed energy balances have been performed on two foods - beef roasts and yellow cake. Consideration of consumer acceptability of this new oven concept have been addressed.

DeWitt, D.P.; Peart, M.V.

1980-04-01

26

Standardized performance tests of collectors of solar thermal energy: Prototype moderately concentrating grooved collectors  

Science.gov (United States)

Prototypes of moderately concentrating grooved collectors were tested with a solar simulator for varying inlet temperature, flux level, and incident angle. Collector performance is correlated in terms of inlet temperature and flux level.

1976-01-01

27

A hot wire radiant energy source for mapping the field of view of a radiometer  

Science.gov (United States)

The design and performance of a calibration device that allows the measurement of a radiometer's field of view are described. The heart of the device is a heated 0.0254-mm (0.001-inch) diameter filament that provides a variable, isothermal line source of radiant energy against a cold background. By moving this discrete line source across the field of view of a radiometer, the radiometer's spatial response can be completely mapped. The use of a platinum filament provides a durable radiation source whose temperature is stable and repeatable to 10 K over the range of 600 to 1200 K. By varying the energy emitted by the filament, the field of view of radiometers with different sensitivities (or multiple channel radiometers) can be totally mapped.

Edwards, S. F.; Stewart, W. F.; Vann, D. S.

1977-01-01

28

The influence of radiant energy on heat losses in small pressurizers, calculated with MODPRESS  

International Nuclear Information System (INIS)

In a previous work, a model for heat transfer coefficient (HTC) calculations was inserted in MODPRESS transient code for PWR pressurizer analysis, so the heat transfer to the surrounding air could be determined. The new routines were verified for Neptunus experimental test number U47, yielding a thermal power loss of 11.4 kW while experimental determinations point to 17.0 kW out. Several HTC correlations were extensively tested for the natural convection between wall and ambient air, but none was capable of justifying such discrepancy. Bearing in mind that, radiation heat loss may account for an important reaction of the global heat loss, in the present work, a HTC relative to the radiant energy was added to the natural convection HTC, resulting in a thermal loss of 16.8 kW. Now, this result compares very well to the experimental measurements, when using for the surface the emissivity of carbon steel. (author)

29

Modeling the spatial distribution of the volumic radiant energy and absorbed dose of radiation in the DNA structure under accelerated heavy ions  

International Nuclear Information System (INIS)

Model approaches are developed to the description of the mechanism of the formation of different types of atomic-level DNA lesions under accelerated heavy ions. The radial distribution of volumic radiant energy and the absorbed dose are calculated in accelerated heavy ions. The radial distribution of volumic radiant energy and the absorbed dose are calculated in accelerated 4He, 12C, and 40Ar ion tracks in the energy range of 3-20 MeV/nucleon. The spatial location of the atoms of an adenine-thymine nucleotide pair is compared with the calculated radial dose and volumic radiant energy distribution

30

Energy and Energy Analysis of a Hybrid Photovoltaic Thermal Double Pass Air Collector  

International Nuclear Information System (INIS)

In this paper an attempt has been made to analyze the performance of semi transparent hybrid PVT double pass air collector. Based on the first law of thermodynamics, energy balance equations are formulated to derive the analytical expression for air temperature at the outlet, as a function of the design and climatic parameters for investigating the performance of semi transparent hybrid PVT air collector. The analysis is based on quasi-steady state condition. This paper shows the detailed analysis of energy and exergy of a semi transparent hybrid PVT double pass air collector and its comparison with single pass air collector for four weather conditions (a, b, c and d type) for five different cities (New Delhi, Bangalore, Mumbai, Srinagar, and Jodhpur) of India. It has been analyzed that if such systems are installed only at 10% of the total residential houses in Delhi, then the total carbon credits earned by the system is found to be Rs. 1767 millions in terms of thermal energy and Rs. 493 millions in terms of exergy for double pass air collector whereas Rs. 1528 millions in terms of thermal energy and Rs. 446 millions in terms of exergy for single pass air collector. The results clearly shows that hybrid PVT double pass air collector have better performance as compared to single pass air collector. (authors)

31

Building Space Heating with a Solar-Assisted Heat Pump Using Roof-Integrated Solar Collectors  

OpenAIRE

A solar assisted heat pump (SAHP) system was designed by using a roof-integrated solar collector as the evaporator, and then it was demonstrated to provide space heating for a villa in Tianjin, China. A building energy simulation tool was used to predict the space heating load and a three dimensional theoretical model was established to analyze the heat collection performance of the solar roof collector. A floor radiant heating unit was used to decrease the energy demand. The measurement resu...

Zhiyong Yang; Li Zhu; Yiping Wang

2011-01-01

32

Heat collector  

Science.gov (United States)

A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

Merrigan, Michael A. (Santa Cruz, NM)

1984-01-01

33

Two-axis movable concentrating solar energy collector  

Science.gov (United States)

Proposed solar-tracker collector assembly with boiler in fixed position, allows use of hard line connections, capable of withstanding optimum high temperature fluid flow. System thereby eliminates need for flexible or slip connection previously used with solar collector systems.

Perkins, G. S.

1977-01-01

34

Spatial sampling considerations of the CERES (Clouds and Earth Radiant Energy System) instrument  

Science.gov (United States)

The CERES (Clouds and Earth Radiant Energy System) instrument is a scanning radiometer with three channels for measuring Earth radiation budget. At present CERES models are operating aboard the Terra, Aqua and Suomi/NPP spacecraft and flights of CERES instruments are planned for the JPSS-1 spacecraft and its successors. CERES scans from one limb of the Earth to the other and back. The footprint size grows with distance from nadir simply due to geometry so that the size of the smallest features which can be resolved from the data increases and spatial sampling errors increase with nadir angle. This paper presents an analysis of the effect of nadir angle on spatial sampling errors of the CERES instrument. The analysis performed in the Fourier domain. Spatial sampling errors are created by smoothing of features which are the size of the footprint and smaller, or blurring, and inadequate sampling, that causes aliasing errors. These spatial sampling errors are computed in terms of the system transfer function, which is the Fourier transform of the point response function, the spacing of data points and the spatial spectrum of the radiance field.

Smith, G. L.; Manalo-Smith, Natividdad; Priestley, Kory

2014-10-01

35

Point response function of the Clouds and Earth Radiant Energy System scanning radiometer  

Science.gov (United States)

An overview of work related to the point response function (PRF) of the Clouds and Earth Radiant Energy System (CERES) scanning radiometer is presented. The aspects of the CERES design that affect the PRF are described, and then the design of the PRF is explained. The PRF was designed by shaping the field of view so as to minimize the blur plus alias errors of the radiance field reconstructed from the CERES measurements. The design is conducted in the Fourier domain. The PRF can then be computed by transforming the resulting transfer function to the physical domain. Alternatively, the PRF can be computed in the physical plane. The PRF of each model of the CERES instrument has been tested in the Radiation Calibration Facility by use of a PRF source and compared well with prediction. CERES instruments are aboard the Terra, Aqua, and Suomi-NPP spacecraft. In orbit, lunar observations are used to validate the PRF. These results showed nominal performance except for the longwave window channel of flight model 2, for which a region of anomalously high sensitivity was found.

Louis Smith, G.; Daniels, Janet L.; Priestley, Kory J.; Thomas, Susan

2014-01-01

36

Solar energy utilisation and evacuated tubular solar collectors  

Energy Technology Data Exchange (ETDEWEB)

Four types of evacuated tubular solar collectors have been constructed and their performance evaluated. The characteristics of the collectors were then compared and their design strengths assessed. One of the designs, a flat absorber with a single glass cover using glass to metal seals was found to have the best performance among the four designs; these included a dewar vessel type collector, a heat pipe collector and a black liquid collector, with a optical efficiency, {eta}{sub o}, of 87.7% and an overall heat loss coefficient, U{sub o}, of 12.3 Wm{sup -2} {sup o}C{sup -1}. The performance of the dewar vessel type and black liquid collectors was found to be comparable to the glass to metal seal collector. A detailed analysis of the optical and thermal processes in evacuated tubular collectors was made. On the basis of this analysis a computer simulation model using a finite difference technique has been developed to predict the performance of evacuated tubular collectors. The simulation results have been compared with the test results for three of the collectors constructed in the present work and also with the published test results for three commercially available collectors. The simulation results show a good agreement with the test results. The computer simulation model was compared with other published models and its advantages and disadvantages discussed. Using the simulation, a parametric study of the three commercially available collectors was made. The results are discussed and the areas of improvement are identified. (Author).

Parand, F.

1991-04-01

37

Solar energy captured by a curved collector designed for architectural integration  

International Nuclear Information System (INIS)

Highlights: • We present a new prototype of solar collector for architectural integration. • Equations of the solar radiation on a curved surface. • We compare the energy intercepted by the prototype with the energy intercepted by conventional collectors. • The prototype can be competitive compared with conventional collectors. - Abstract: In this paper we present a prototype for a new type of solar thermal collector designed for architectural integration. In this proposal, the conventional geometry of a flat solar thermal collector is changed to a curved geometry, to improve its visual impact when mounted on a building facade or roof. The mathematical equations for the beam and diffuse solar radiation received by a collector with this geometry are developed for two different orientations, horizontal and vertical. The performance of this curved prototype, in terms of solar radiation received, is compared with a conventional tilted-surface collector for different orientations in Madrid (Spain). The comparison is made for typical clear-sky days in winter and summer as well as for an entire year. The results demonstrate that the curved collector only receives between 12% and 25% less radiation than the conventional tilted-surface collectors when oriented horizontally, depending on the azimuth of the curved surface, although these percentages are reduced to approximately 50% when the collector is oriented vertically

38

Truncation of CPC solar collectors and its effect on energy collection  

Energy Technology Data Exchange (ETDEWEB)

Analytic expressions are derived for the angular acceptance function of two-dimensional compound parabolic concentrator solar collectors (CPC's) of arbitrary degree of truncation. Taking into account the effect of truncation on both optical and thermal losses in real collectors, we also evaluate the increase in monthly and yearly collectible energy. Prior analyses that have ignored the correct behavior of the angular acceptance function at large angles for truncated collectors are shown to be in error by 0-2% in calculations of yearly collectible energy for stationary collectors.

Carvalho, M.J.; Collares-Pereira, M.; Gordon, J.M.; Rabl, A.

1985-01-01

39

Influence of reflectance from flat aluminum concentrators on energy efficiency of PV/Thermal collector  

International Nuclear Information System (INIS)

In this paper the results of the influence of reflectance from flat plate solar radiation concentrators made of Al sheet and Al foil on energy efficiency of PV/Thermal collector are presented. The total reflectance from concentrators made of Al sheet and Al foil is almost the same, but specular reflectance which is bigger in concentrators made of Al foil results in increase of solar radiation intensity concentration factor. With the increase of solar radiation intensity concentration factor, total daily thermal and electrical energy generated by PV/Thermal collector with concentrators increase. In this work also optimal position of solar radiation concentrators made of Al sheet and Al foil and appropriate thermal and electrical efficiency of PV/Thermal collector have been determined. Total energy generated by PV/Thermal collector with concentrators made of Al foil in optimal position is higher than total energy generated by PV/Thermal collector with concentrators made of Al sheet.

40

Thermal conduction in evacuated concentric tubular solar energy collectors degraded by low pressure gas  

Science.gov (United States)

Thermal conduction has been investigated in evacuated concentric glass tubular solar energy collectors degraded by the accumulation of low pressure gas in the annular region. Two different types of dependence of conducted heat flux with temperature difference between absorber tube and envelope have been observed. Experiments on collectors sealed with controlled quantities of known gases indicated that the different temperature dependences are associated with different energies of adsorption of molecules on the collector surfaces. The heat conduction has been modelled theoretically using measured accommodation coefficients and some typical adsorption energies for various molecules.

Harding, G. L.; Window, B.

1981-05-01

41

Integrated function nonimaging concentrating collector tubes for solar thermal energy  

Science.gov (United States)

A substantial improvement in optical efficiency over contemporary external reflector evacuated tube collectors has been achieved by integrating the reflector surface into the outer glass envelope. Described are the design fabrication and test results for a prototype collector based on this concept. A comprehensive test program to measure performance and operational characteristics of a 2 sq m panel (45 tubes) has been completed. Efficiencies above 50% relative to beam at 200 C have been repeatedly demonstrated. Both the instantaneous and long term average performance of this totally stationary solar collector are comparable to those for tracking line focus parabolic troughs. The yield, reliability and stability of performance achieved have been excellent. Subcomponent assemblies and fabrication procedures have been used which are expected to be compatible with high volume production. The collector has a wide variety of applications in the 100 to 300 C range including industrial progress heat, air conditioning and Rankine engine operation.

Winston, R.; Ogallagher, J. J.

1982-09-01

42

A System for Determining Parameters of a Particle by Radiant Energy Scattering Techniques, Patent Application.  

Science.gov (United States)

The system for determining parameters of a particle described in this document is a government-owned invention that is available for licensing. The background of the invention is outlined, and drawings of the system together with a detailed description of its function are provided. A collector contains a hole and annular apertures for transmitting…

National Bureau of Standards (DOC), Washington, DC.

43

Climate Model Evaluation using New Datasets from the Clouds and the Earth's Radiant Energy System (CERES)  

Science.gov (United States)

There are some in the science community who believe that the response of the climate system to anthropogenic radiative forcing is unpredictable and we should therefore call off the quest . The key limitation in climate predictability is associated with cloud feedback. Narrowing the uncertainty in cloud feedback (and therefore climate sensitivity) requires optimal use of the best available observations to evaluate and improve climate model processes and constrain climate model simulations over longer time scales. The Clouds and the Earth s Radiant Energy System (CERES) is a satellite-based program that provides global cloud, aerosol and radiative flux observations for improving our understanding of cloud-aerosol-radiation feedbacks in the Earth s climate system. CERES is the successor to the Earth Radiation Budget Experiment (ERBE), which has widely been used to evaluate climate models both at short time scales (e.g., process studies) and at decadal time scales. A CERES instrument flew on the TRMM satellite and captured the dramatic 1998 El Nino, and four other CERES instruments are currently flying aboard the Terra and Aqua platforms. Plans are underway to fly the remaining copy of CERES on the upcoming NPP spacecraft (mid-2010 launch date). Every aspect of CERES represents a significant improvement over ERBE. While both CERES and ERBE measure broadband radiation, CERES calibration is a factor of 2 better than ERBE. In order to improve the characterization of clouds and aerosols within a CERES footprint, we use coincident higher-resolution imager observations (VIRS, MODIS or VIIRS) to provide a consistent cloud-aerosol-radiation dataset at climate accuracy. Improved radiative fluxes are obtained by using new CERES-derived Angular Distribution Models (ADMs) for converting measured radiances to fluxes. CERES radiative fluxes are a factor of 2 more accurate than ERBE overall, but the improvement by cloud type and at high latitudes can be as high as a factor of 5. Diurnal cycles are explicitly resolved by merging geostationary satellite observations with CERES and MODIS. Atmospheric state data are provided from a frozen version of the Global Modeling and Assimilation Office- Data Assimilation System at the NASA Goddard Space Flight Center. In addition to improving the accuracy of top-of-atmosphere (TOA) radiative fluxes, CERES also produces radiative fluxes at the surface and at several levels in the atmosphere using radiative transfer modeling, constrained at the TOA by CERES (ERBE was limited to the TOA). In all, CERES uses 11 instruments on 7 spacecraft all integrated to obtain climate accuracy in TOA to surface fluxes. This presentation will provide an overview of several new CERES datasets of interest to the climate community (including a new adjusted TOA flux dataset constrained by estimates of heat storage in the Earth system), show direct comparisons between CERES ad ERBE, and provide a detailed error analysis of CERES fluxes at various time and space scales. We discuss how observations can be used to reduce uncertainties in cloud feedback and climate sensitivity and strongly argue why we should NOT "call off the quest".

Loeb, Norman G.; Wielicki, Bruce A.; Doelling, David R.

2008-01-01

44

Standardized performance tests of collectors of solar thermal energy: An evacuated flatplate copper collector with a serpentine flow distribution  

Science.gov (United States)

Basic test results are given for a flat plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and one coolant flow rate. Collector efficiency is correlated in terms of inlet temperature and flux level.

Johnson, S. M.

1976-01-01

45

Standardized performance tests of collectors of solar thermal energy - A flat-plate copper collector with parallel mylar striping  

Science.gov (United States)

Basic test results are reported for a flat plate solar collector whose performance was determined in a solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and one coolant flow rate. Collector efficiency is correlated in terms of inlet temperature and flux level.

Johnson, S. M.

1976-01-01

46

Standardized performance tests of collectors of solar thermal energy: A selectively coated, steel collector with one transparent cover  

Science.gov (United States)

Basic test results are presented of a flat-plate solar collector whose performance was determined in solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and coolant flow rates. Collector efficiency was correlated in terms of inlet temperature and flux level.

1976-01-01

47

Performance of the Clouds and the Earth's Radiant Energy System (CERES) Flight Model 5 (FM5) instrument on NPP mission  

Science.gov (United States)

Clouds and the Earth's Radiant Energy System (CERES) instrument was designed to provide accurate measurements for the long-term monitoring of Earth's radiation energy budget. Flight Model 5, the sixth of the CERES instrument was launched aboard the NPP spacecraft on October 2011 and it has started the Earth-viewing measurements on January 26, 2012. The CERES instrument with the three scanning sensors measure radiances in 0.3 to 5.0 micron region with Shortwave sensor, 0.3 to elevation offset in the sensor measurement will be determined from the spacecraft pitch manuveur activity viewing the deep space. This paper covers the early-orbit checkout activities and the overall performance of the CERES-FM5 instrument. The postlaunch calibration and the validation results from the instrument are presented.

Thomas, Susan; Priestley, Kory J.; Hess, Phillip C.; Wilson, Robert S.; Smith, Nathaniel P.; Timcoe, Mark G.; Shankar, Mohan; Walikainen, Dale R.

2012-09-01

48

Optimizing the shape of a surge-and-pitch wave energy collector using a genetic algorithm  

Energy Technology Data Exchange (ETDEWEB)

This study forms part of research into the optimization of the shape of a wave energy collector to improve energy extraction using genetic algorithms. The wave energy collector geometry uses a parametric description based upon bi-cubic B-spline surfaces, generated from a relatively small number of control points to reduce the dimensionality of the search space. The collector shapes that are optimized have either one or two planes of symmetry. An elementary cost function is used to determine the performance of each candidate solution. The collectors move in two degrees of freedom (surge-and-pitch), and are optimally tuned to absorb the greatest power from a number of incident regular waves, the results being weighted according to a generalized occurrence distribution. High velocities and large collector volumes are penalized. A benchmark collector shape, against which the optimized shapes are compared, is identified. The overall optimization strategy entails performing repeated runs of the algorithm for a fixed number of generations, then restarting the optimization with the run that produces the best result. An appraisal of the results is made, looking at the performance of all the shapes assessed as well as those deemed the best. (author)

McCabe, A.P.; Aggidis, G.A.; Widden, M.B. [Engineering Department, Renewable Energy Research Group, Lancaster University, Lancaster LA1 4YR (United Kingdom)

2010-12-15

49

Membrane-based space energy collector: A conceptual study  

Science.gov (United States)

In this work the shape characteristics of a parabolic structure that consists of an initially flat circular membrane subject to solar radiation pressure in the space environment are examined. This problem arises in the analysis of space systems such as solar power collectors and solar sails. This paper presents parametric studies aimed at determining the power concentration capacity of a non-ideally reflecting flat circular membrane as a function of its radius size and thickness. The shape of the deformed membrane is close to parabolic. Both numerical simulations and analytical study show that the thin membrane subject solely to solar radiation pressure can concentrate the sunlight power several hundred times.

Couceiro, F.; Gamboa, P. V.; Silva, J. M.; Guerman, A. D.

2013-06-01

50

Relationship Between the Clouds and the Earth's Radiant Energy System (CERES) Measurements and Surface Temperatures of Selected Ocean Regions  

Science.gov (United States)

Clear sky longwave radiances and fluxes are compared with the sea surface temperatures for three oceanic regions: Atlantic, Indian, and Pacific. The Clouds and the Earth's Radiant Energy System (CERES) measurements were obtained by the three thermistor bolometers: total channel which measures the radiation arising from the earth-atmosphere system between 0.3 - greater than 100 micrometers; the window channel which measures the radiation from 8-12 micrometers; and the shortwave channel which measures the reflected energy from 0.3 - less than 5.0 micrometers. These instruments have demonstrated measurement precisions of approximately 0.3% on the International Temperature Scale of 1990 (ITS-90) between ground and on-orbit sensor calibrations. In this work we have used eight months of clear sky earth-nadir-view radiance data starting from January 1998 through August 1998. We have found a very strong correlation of 0.97 between the CERES window channel's weekly averaged unfiltered spectral radiance values at satellite altitude (350 km) and the corresponding weekly averaged sea surface temperature (SST) data covering all the oceanic regions. Such correlation can be used in predicting the sea surface temperatures using the present CERES Terra's window channel radiances at satellite altitude very easily.

Pandey, Dhirendra, K.; Lee, Robert B., III; Brown, Shannon B.; Paden, Jack; Spence, Peter L.; Thomas, Susan; Wilson, Robert S.; Al-Hajjah, Aiman

2001-01-01

51

Mathematical modelling, variational formulation and numerical simulation of the energy transfer process in a gray plate in the presence of a thermal radiant source  

International Nuclear Information System (INIS)

The energy transfer process in a gray, opaque and rigid plate, heated by an external thermal radiant source, is considered. The source is regarded as a spherical black body, with radius a (a ? 0) and uniform heat generation, placed above the plate. A mathematical model is constructed, assuming that the heat transfer from/to the plate takes place by thermal radiation. The obtained mathematical model is nonlinear. Is presented a suitable variational principle which is employed for simulating some particular cases. (author)

52

High intensity discharge lamp self-adjusting ballast system sensitive to the radiant energy or heat of the lamp  

Energy Technology Data Exchange (ETDEWEB)

This patent describes a self-adjusting ballast system for mercury vapor, high intensity discharge lamps having outputs of 100 watts or greater, comprising: a direct current source; a lamp circuit containing a high intensity discharge lamp; sensing means for sensing the radiant energy output of the lamp; a pulse width modulator which, in response to the output of the sensing means, varies the width of the pulses that power the lamp during warm-up of the lamp; a high frequency oscillator; a DC to AC converter that converts current from the direct source to pulses of alternating current for powering the lamp, the converter comprising: at least one switch for gating current to the lamp; a switch control means, responsive to the high frequency oscillator, for controlling the switch and controlling the frequency of the alternating current pulses that power the lamp; current sensing means for sensing the current being supplied to the lamp; and current control means for limiting the current through the lamp to a predetermined safe level when the current sensed by the current sensing means exceeds a reference value.

Kuhnel, D.S.; Ottenstein, S.A.

1987-07-21

53

Performance assessment of the Clouds and the Earth's Radiant Energy System (CERES) instruments aboard Terra and Aqua spacecraft  

Science.gov (United States)

Clouds and the Earth's Radiant Energy System (CERES) instruments were designed to measure the reflected shortwave and emitted longwave radiances of the Earth's radiation budget and to investigate the cloud interactions with global radiances for the long-term monitoring of Earth's climate. The three scanning thermistor bolometer sensors on CERES measure broadband radiances in the shortwave (0.3 to 5.0 micrometer), total (0.3 to lamp, and a solar diffuser plate known as the Mirror Attenuator Mosaic (MAM). The ICM calibration results are instrumental in determining the changes in CERES sensors' gains after launch from the prelaunch determined values and the on-orbit gain variations. In addition to the broadband response changes derived from the on-board blackbody and the tungsten lamp, the shortwave and the total sensors show a spectrally dependent drop in responsivity in the shorter wavelegth region below one micron that were brought to light through validation studies. The spectrally dependent changes were attributed to the instrument operational modes and the corrections were derived using the sensor radiance comparisons. This paper covers the on-orbit behavior of CERES sensors aboard the Terra and Aqua spacecraft and the determination of the sensor response changes utilising the in-flight calibration and the radiance measurement comparisons viewing various targets. The corrections for the sensor response changes were incorporated in the radiance calculations of CERES Edition3 data products.

Thomas, Susan; Priestley, K. J.; Shankar, M.; Smith, N. M.; Loeb, N. G.; Walikainen, D. R.; Hess, P. C.; Wilson, R. S.; Smith, N. P.

2013-09-01

54

Validation studies performed on Clouds and the Earth's Radiant Energy system (CERES) instrument sensors aboard EOS Terra and Aqua spacecraft  

Science.gov (United States)

Clouds and the Earth's Radiant Energy system (CERES) sensors provide accurate measurements for the long-term monitoring of the Earth's radiation budget components. The three scanning thermistor bolometer sensors on CERES measure broadband radiances in the shortwave (0.3 to 5.0 micrometer), total (0.3 to >100 micrometer) and in 8 - 12 micrometer water vapor window regions. Currently four of the CERES instruments (Flight Models 1 through 4 [FM1 - FM4]) are flying aboard EOS Terra and Aqua platforms with two instruments aboard each spacecraft. The sensor calibrations are performed with onboard blackbody sources and a tungsten lamp as well as a solar diffuser plate known as the Mirror Attenuator Mosaic (MAM). The calibration results collectively depict the ground to orbit shifts and the on-orbit drifts in the sensor reponses. Deep convective clouds and tropical ocean are used as validation targets to understand the sensors' stability on-orbit. With two CERES instruments on the same platform, comparison of measurements from similar sensors viewing the same geolocation are performed. The different calibration and validation studies performed on CERES bring to light the radiometric gain and spectral variation of the sensors from pre and post launch. This paper discusses briefly the contribution of each calibration and validation study in understanding CERES sensors' behavior. It also shows the results from these studies which enabled to correct the data products with a calibration stability of better than 0.2%.

Thomas, Susan; Priestley, K. J.; Wilson, R. S.; Walikainen, D. R.; Matthews, G. M.

2006-08-01

55

A study on energy gain on evacuated collector tube with cylindric absorber on building southern facade  

Energy Technology Data Exchange (ETDEWEB)

According to the Clear-Day Model, daily energy gain and its annual variation of single evacuated collector tube with cylindric absorber in three different installation on building southern facade are studied. The solar energy gain of vertical installed tube and east-west horizontal installed tube comparing with local latitude tilted installed tube are presented. During the summer season the east-west horizontal installed tube has more solar energy gain than the vertical installed tube. (orig.)

Min Zijian [Information Engineering Coll., Capital Normal Univ., BJ (China); Ge Hongchuan [Beijing Eurocon Solar Energy Tech. Co., Ltd., BJ (China); Ma Yiqing [Special Education Coll. of Beijing Union Univ., BJ (China)

2008-07-01

56

DESIGN AND FABRICATION OF SOLAR TRACKER SYSTEM USING HYDRAULIC ACTUATOR FOR PARABOLIC SOLAR COLLECTOR  

Directory of Open Access Journals (Sweden)

Full Text Available Parabolic solar collector collects the radiant energy emitted from the sun and focuses at a point. However, the basic problem with the collector was to track the path of the sun as the sun moves from east to west for the entire day the solar collector does not move. In today’s era as the demand of the renewable source of energy are going to be most important and precious. As we know non renewable sources of energy are consuming very rapidly. The idea of solar tracking comes into sense. Now coming to Our research paper idea; it is to make a solar tracker to track the path of the sun with use of hydraulic actuator arrangement , This paper gives the information about to how to track the path of the sun so that we can trap the maximum energy of the sun.

Dr.Nitin Shrivastava*

2015-03-01

57

Potential Use of Radiant Walls to Transfer Energy Between two Building Zones  

DEFF Research Database (Denmark)

Due to a reduced energy demand in low energy buildings, low temperature heating and high temperature cooling can be used to control thermal comfort. Nevertheless, highly varying heat loads due to solar radiation can create sometimes an imbalanced energy demand inside the building. Instead of being considered as a disturbance, this asymmetry can be used as a heat source for another zone of the building. By means of computer simulations, the possibility of shifting the energy demand between two office rooms with different thermal loads has been studied. Due to the small temperature difference between the two zones, capillary tubes embedded in the surface of walls are used to exchange heat from a south-facing room to a north-facing room. In addition to having a better indoor climate, the total heating and cooling consumption decreases when running the system. A comparison has also been performed with a system exchanging room air directly.

Le Dreau, Jerome; Heiselberg, Per

2011-01-01

58

Radiometric stability results of clouds and the Earth's radiant energy system (CERES) instrument sensors aboard EOS Terra and Aqua spacecraft  

Science.gov (United States)

Clouds and the Earth's Radiant Energy System (CERES) instruments were designed to measure the reflected shortwave and emitted longwave radiances of the Earth's radiation budget and to investigate the cloud interactions with global radiances for the long-term monitoring of Earth's climate. CERES instrument has three scanning thermistor bolometers that measure broadband radiances in the shortwave (0.3 to 5.0 micrometer), total (0.3 to >100 micrometer) and 8 - 12 micrometer water vapor window regions. Four CERES instruments (Flight Models1 through 4) are flying aboard EOS Terra and Aqua platforms with two instruments aboard each spacecraft. The pre-launch accuracy requirements for CERES were 1.0% in the shortwave and 0.5% in longwave regions. The in-flight calibration of CERES sensors are carried out using the internal calibration module (ICM) comprising of blackbody sources and tungsten lamp, and a solar diffuser plate known as the Mirror Attenuator Mosaic (MAM). The ICM and MAM calibration results are instrumental in understanding the ground to flight shift and in-flight drifts in CERES sensors' gains. Inter and intra instrument validation studies are conducted on the CERES measurements to monitor the behavior of the sensors in various spectral regions. Targets such as deep convective clouds and tropical ocean are used to evaluate the sensors' stability within an instrument. With two CERES instruments on same platform, inter comparison of similar sensor measurements viewing the same geolocation are also conducted. The results from these individual studies have collectively given an understanding of each CERES sensor's behavior in different spectral regions. This paper discusses the results from each of these studies which facilitated the correction of CERES data products with a calibration stability better than 0.2%. Keywords: CERES, EOS Instrument, Radiometry, Calibration, Validationt

Thomas, Susan; Priestley, K. J.; Wilson, R. S.; Matthews, G. M.; Walikainen, D. R.; Cooper, D. L.; Hess, P. C.

2006-12-01

59

Assessment of the Clouds and the Earth's Radiant Energy System (CERES) Flight Model 5 (FM5) instrument performance and stability  

Science.gov (United States)

The Clouds and the Earth's Radiant Energy System (CERES) scanning radiometer is designed to measure the solar radiation reflected by the Earth and thermal radiation emitted by the Earth. Four CERES instruments are supporting the EOS missions; two aboard the Terra spacecraft, launched in 1999 and two aboard the Aqua spacecraft, launched in 2002. A fifth instrument, Flight Model 5 (FM5), launched in October 2011 aboard the S-NPP satellite, began taking radiance measurements on January 27th, 2012. The CERES FM5 instrument uses three scanning thermistor bolometers to make broadband radiance measurements in the shortwave (0.3 - 5.0 micrometers), total (0.3 - internal calibration module (ICM) used for in-flight calibration is built into the CERES instrument package consisting of an anodized aluminum blackbody source for calibrating the total and window sensors, and a shortwave internal calibration source (SWICS) for the shortwave sensor. The ICM sources, along with a solar diffusor called the Mirror Attenuator Mosaic (MAM), are used to define shifts or drifts in the sensor response over the life of the mission. In addition, validation studies are conducted to assess the pointing accuracy of the instrument and understand any spectral changes that may occur with the sensors allowing for corrections to be made to the radiance calculations in later CERES data products. This paper summarizes the on-orbit behavior of the CERES FM5 instrument by outlining trends in the internal calibration data and discussing the various validation studies used to assess the performance and stability of the instrument.

Smith, Nathaniel P.; Thomas, Susan; Shankar, Mohan; Szewczyk, Z. P.; Wilson, Robert S.; Walikainen, Dale R.; Daniels, Janet L.; Hess, Phillip C.; Priestley, Kory J.

2014-09-01

60

Clouds and the Earth's Radiant Energy System (CERES) instrument level 1 science data validation plan for geolocated radiances  

Science.gov (United States)

From spacecraft platforms, the clouds and the Earth's radiant energy system (CERES) scanning thermistor bolometers are designed to measure broadband Earth-reflected solar shortwave (0.3 - 5.0 micrometer) and Earth-emitted long wave (5.0 - greater than 100 micrometer) radiances as well as emitted longwave radiances in the 8 - 12 micrometer water vapor window over geographical footprints as small as 10 kilometers at the nadir. In ground vacuum facilities, the thermistor bolometers and in-flight blackbody and tungsten lamp calibration systems are being calibrated using radiometric sources tied to the international temperature scale of 1990 (ITS'90). Using the in-flight calibration systems, the bolometers will be calibrated periodically before and after spacecraft launch to verify the stability of the bolometers responses and to determine response drifts/shifts if they occur. The in-flight systems calibration analyses along with validation analyses will be used to determine the flight data reduction coefficients (instrument gains and offsets) which will be used to convert the bolometer measurements into calibrated radiances at the top-of-the-atmosphere (approximately 30 km). If a bolometer response shifts or drifts more than 0.5% in the longwave region or more than 1.0% in the shortwave region, and if the validation studies verify the bolometer response change, the flight data reduction coefficients will be corrected. A coastline detection method, using strong contrasting longwave ocean-land scenes, will be used to assess error limits on the geographical locations of the radiances. The detection method was successfully used to assess upper limits (6 km) on the geolocation errors for the Earth radiation budget satellite (ERBS) bolometric measurements of longwave radiances. For CERES, the detection method may be extended to shortwave radiances. In this paper, elements of the CERES instrument level 1 validation plan radiometric strategies are presented as well as the geolocation validation approaches.

Lee, Robert B., III; Childers, Brooks A.; Smith, G. Louis; Paden, Jack; Pandey, Dhirendra K.; Thomas, Susan

1996-11-01

61

Reflection due to fluorescence of a radiant energy flux impinging on a planar surface  

International Nuclear Information System (INIS)

In this paper, the authors describe a study of the manner in which L-K transitions reflect radiation impinging upon a plane layer of thickness l. They assume that the energy distribution of the incident photons is a Planck function. Fluorescence due to K-shell vacancies produced by photoionisation is the only effect taken into consideration. Fluorescence due to other inner-shell processes is neglected. They consider that the atoms of the materials have a K-shell binding energy much greater than those of the L or M-subshells. They also assume that the temperature of the blackbody spectrum is sufficiently high for K-shell ionizations. Moreover, the fluorescence yields due to other inner-shell vacancies are small. By solving the transfer equation, they shall be able to calculate the re-emitted flux and, consequently, the albedo of the layer. Photons with energy greater than the K-shell binding energy photoionize the K-shell of the atoms and induce immediate L-K transitions, thus causing emission of photons with energy hvKL = EK-EL or Auger electrons. They give numerical results to the case when the Auger effect is not taken into account. This neglect can be justified when induced processes are very important, They shall then compare the results with those obtained when account is taken of maximum ejections of Auger electrons

62

Radiant cooling of an enclosure  

International Nuclear Information System (INIS)

The purpose of this study is to analyze the potential for radiant cooling using the atmospheric sky window and to evaluate the desired characteristics of a radiant cooling material (RCM) applied to the ceiling window of a three-dimensional enclosure. The thermal characteristics of the system are governed by the geometry, ambient temperature, sky radiative temperature, amount of solar energy and its direction, heat transfer modes, wall radiative properties, and radiative properties of the RCMs. A semi-gray band analysis is utilized for the solar and infrared bands. The radiosity/irradiation method is used in each band to evaluate the radiant exchanges in the enclosure. The radiative properties for the RCM are varied in a parametric study to identify the desired properties of RCMs. For performance simulation of real RCMs, the radiative properties are calculated from spectral data. The desired solar property is a high reflectance for both opaque and semi-transparent RCMs. For a semi-transparent RCM, a low value of the solar transmittance is preferred. The desired infrared property is a high emittance for an opaque RCM. For a semi-transparent RCM, a high infrared transmittance is desired, and the emittance should be greater than zero

63

Reflection due to flUOrescence of a radiant energy flux impinging on a planar surface  

International Nuclear Information System (INIS)

In this paper, the authors describe a study of the manner in which L-K transitions reflect radiation impinging upon a plane layer of thickness. They assume that the energy distribution of the incident photons is a Planck function. Fluorescence due to K-shell vacancies produced by photoionization is the only effect taken into consideration. Fluorescence due other inner-shell processes is neglected. The authors consider that the atoms of the material have a K-shell binding energy much greater than those of the L or M-subshells. We also assume that the temperature of the blackbody spectrum is sufficiently high for K-shell ionizations. Moreover, the fluorescence yields due to other inner-shell vacancies are small. By solving the transfer equation, they shall be able to calculate the re-emitted flux and, consequently, the albedo of the layer

64

Assessment of Energy, Environmental and Economic Performance of a Solar Desiccant Cooling System with Different Collector Types  

OpenAIRE

Desiccant-based air handling units can achieve reductions in greenhouse gas emissions and energy savings with respect to conventional air conditioning systems. Benefits are maximized when they interact with renewable energy technologies, such as solar collectors. In this work, experimental tests and data derived from scientific and technical literature are used to implement a model of a solar desiccant cooling system, considering three different collector technologies (air, flat-plate and eva...

Giovanni Angrisani; Carlo Roselli; Maurizio Sasso; Francesco Tariello

2014-01-01

65

Magnetohydrodynamic research program of the MHD Energy center at Mississippi State University and structural features of MHD radiant boilers  

Science.gov (United States)

Magnetohydrodynamic is conducted largerly through use of test stand which simulates conditions in the MHD gas stream. Continual modification of the test stand to reflect experimental results produced a test stand capable of test runs of 100 hours; runs of more than 500 hours are planned. The test stand is described, and experimental results are discussed. The design and construction of MHD radiant boiler are described. The radiant furnance serves several functions in a heat recovery and seed recovery system; it cools flue gases to a temperature suitable for entrance to the secondary superheater; it generates steam; it provides for the removal of molten ash at high temperatures; and it provides access for intrusive and nonintrusive instrumentation to the gas-side environment.

Shepard, W. S.

66

Compensation for spectral darkening of short wave optics occurring on the cloud's and the Earth's radiant energy system  

Science.gov (United States)

Cloud's and the Earth's Radiant Energy System (CERES) is an investigation into the role of clouds and radiation in the Earth's climate system. Four CERES scanning thermistor bolometer instruments are currently in orbit. Flight model 1 (FM1) and 2 (FM2) are aboard the Earth Observing System (EOS) Terra satellite and FM3 and FM4 are aboard the EOS Aqua satellite. Each CERES instrument measures in three broadband radiometric regions: the shortwave (SW 0.3-5?m), total (0.3- > 100?m), and window (8-12?m). It has been found that both CERES instruments on the Terra platform imply that the SW flux scattered from the Earth had dropped by up to 2% from 2000 to 2004. No climatological explanation for this drop could be found, suggesting the cause was a drift in both the Terra instruments. However, the onboard calibration lamps for the SW channels do not show a change in gain of this magnitude. Experience from other satellite missions has shown that optics in the orbital environment can become contaminated, severely reducing their transmission of ultra-violet (UV) radiation. Since the calibration lamps emit little radiance in the UV spectral region it was suggested that contaminates could be responsible for an undetectable 'spectral darkening' of the CERES SW channel optics and hence the apparent drop in SW flux. Further evidence for this was found by looking at the comparison between simultaneous measurements made by FM1 and FM2. The proposed mechanisms for contaminant build up would not apply to a CERES instrument operating in the normal cross track scan mode. Indeed it was found from the comparison between CERES instruments on Terra that the response of the instrument operating in rotating azimuth plane (RAPS) mode consistently dropped relative to the other cross track instrument. Since at all times one of the instruments operates in cross track mode, where it is not subject to spectral darkening, it allowed that unit to be used as a calibration standard from which the darkening of the other RAPS instrument can be measured. A table of adjustment coefficients to compensate for this spectral darkening are therefore derived in this paper. These figures are designed to be multiplied by SW fluxes or radiances produced in the climate community using Edition 2 CERES data. SW CERES measurements that have been revised using these coeffcients are therefore to be referred to as ERBE-like Edition2_Rev1 or SSF Edition2B_Rev1 data in future literature. Current work to fully characterize the effect of spectral darkening on the instrument spectral response before the release of Edition 3 data is also described.

Matthews, Grant; Priestley, Kory; Spence, Peter; Cooper, Denise; Walikainen, Dale

2005-08-01

67

Heat transfer and energy analysis of a solar air collector with smooth plate  

Science.gov (United States)

The heat transfer and thermal performance of a single pass solar air heater a smooth plate was investigated experimentally. In the present paper, energy and heat transfer analysis of a solar air collector with smooth plate, this technique is used to determine the optimal thermal performance of flat plate solar air heater by considering the different system and operating parameters to obtain maximum thermal performance. Thermal performance is obtained for different mass flow rate varying in the array 0.0108-0.0202 kg/s with five values, solar intensity; tilt angle and ambient temperature. We discuss the thermal behavior of this type of collector with new design and with my proper construction. An experimental study was carried out on a prototype installed on the experimental tests platform within the University of Biskra in the Algeria. The effects of air mass flow rate, emissivity of channel plates and wind heat transfer coefficient on the accuracy of the criterion are also investigated.

Chabane, Foued; Moummi, Noureddine

2014-04-01

68

Energy and exergy analysis of photovoltaic-thermal collector with and without glass cover  

International Nuclear Information System (INIS)

In photovoltaic-thermal (PV/T) technology, the use of glass cover on the flat-plate hybrid solar collector is favorable to the photothermic process but not to the photovoltaic process. Because of the difference in the usefulness of electricity and thermal energy, there is often no straight forward answer on whether a glazed or unglazed collector system is more suitable for a specific application. This glazing issue was tackled in this paper from the viewpoint of thermodynamics. Based on experimental data and validated numerical models, a study of the appropriateness of glass cover on a thermosyphon-based water-heating PV/T system was carried out. The influences of six selected operating parameters were evaluated. From the first law point of view, a glazed PV/T system is found always suitable if we are to maximize the quantity of either the thermal or the overall energy output. From the exergy analysis point of view however, the increase of PV cell efficiency, packing factor, water mass to collector area ratio, and wind velocity are found favorable to go for an unglazed system, whereas the increase of on-site solar radiation and ambient temperature are favorable for a glazed system

69

Novel concept for producing energy integrating a solar collector with a man made mountain hollow  

International Nuclear Information System (INIS)

The concept of the solar chimney thermal power technology was proven with the successful operation of the Manzanares prototype built in the 1980s. However, all previous attempts at producing energy from a commercial solar chimney thermal power plant on a large scale have failed because of bad engineering and safety. A novel concept for producing energy by integrating a solar collector with a mountain hollow is presented and described. Solar energy is collected in the collector and heats the ground, which is used to store heat energy and heat the indoor air. Then, the hot air is forced by the pressure difference between it and the ambient air to move along the tilted segment and up the vertical segment of the 'chimney', driving the turbine generators to generate electricity. The mountain hollow, formed by excavation in a large-elevation mountain, can avoid the safety issues of erecting a gigantic concrete chimney, which is needed for commercial solar chimney thermal power plants. Furthermore, it can also save a great amount of construction materials for constructing a robust chimney structure and reduce the energy cost to a level less than that of a clean coal power plant, providing a good solution to the reclamation and utilization of undeveloped mountains, especially in mountainous countries

70

Novel concept for producing energy integrating a solar collector with a man made mountain hollow  

Energy Technology Data Exchange (ETDEWEB)

The concept of the solar chimney thermal power technology was proven with the successful operation of the Manzanares prototype built in the 1980s. However, all previous attempts at producing energy from a commercial solar chimney thermal power plant on a large scale have failed because of bad engineering and safety. A novel concept for producing energy by integrating a solar collector with a mountain hollow is presented and described. Solar energy is collected in the collector and heats the ground, which is used to store heat energy and heat the indoor air. Then, the hot air is forced by the pressure difference between it and the ambient air to move along the tilted segment and up the vertical segment of the 'chimney', driving the turbine generators to generate electricity. The mountain hollow, formed by excavation in a large-elevation mountain, can avoid the safety issues of erecting a gigantic concrete chimney, which is needed for commercial solar chimney thermal power plants. Furthermore, it can also save a great amount of construction materials for constructing a robust chimney structure and reduce the energy cost to a level less than that of a clean coal power plant, providing a good solution to the reclamation and utilization of undeveloped mountains, especially in mountainous countries. (author)

Zhou, Xinping [School of Civil Engineering and Mechanics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074 (China); Yang, Jiakuan; Wang, Jinbo; Xiao, Bo [School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road Wuhan, Hubei 430074 (China)

2009-03-15

71

Novel concept for producing energy integrating a solar collector with a man made mountain hollow  

Energy Technology Data Exchange (ETDEWEB)

The concept of the solar chimney thermal power technology was proven with the successful operation of the Manzanares prototype built in the 1980s. However, all previous attempts at producing energy from a commercial solar chimney thermal power plant on a large scale have failed because of bad engineering and safety. A novel concept for producing energy by integrating a solar collector with a mountain hollow is presented and described. Solar energy is collected in the collector and heats the ground, which is used to store heat energy and heat the indoor air. Then, the hot air is forced by the pressure difference between it and the ambient air to move along the tilted segment and up the vertical segment of the 'chimney', driving the turbine generators to generate electricity. The mountain hollow, formed by excavation in a large-elevation mountain, can avoid the safety issues of erecting a gigantic concrete chimney, which is needed for commercial solar chimney thermal power plants. Furthermore, it can also save a great amount of construction materials for constructing a robust chimney structure and reduce the energy cost to a level less than that of a clean coal power plant, providing a good solution to the reclamation and utilization of undeveloped mountains, especially in mountainous countries.

Zhou Xinping [School of Civil Engineering and Mechanics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074 (China)], E-mail: zhxpmark@hotmail.com; Yang Jiakuan; Wang Jinbo; Xiao Bo [School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road Wuhan, Hubei 430074 (China)

2009-03-15

72

Review of solar-energy drying systems 3: low temperature air-heating solar collectors for crop drying applications  

Energy Technology Data Exchange (ETDEWEB)

The efficient design and construction of solar-energy air-heating collectors are critical to the overall performance of the distributed (indirect mode) and mixed-mode designs of either or passive solar-energy crop dryers. A review of the various designs and the performance evaluation technique of flat-plate solar-energy air-heating collectors for low temperature (i.e. temperature elevations between 10{sup o}C-35{sup o}C above ambient) solar-energy crop drying applications are presented. The appropriateness of each design and the component materials selection guidelines are highlighted. (author)

Ekechukwu, O.V. [University of Nigeria, Nsukka (Nigeria). Energy Research Centre; Norton, B. [University of Ulster, Newtownabbey (United Kingdom). PROBE

1999-04-01

73

Geothermal energy - Handbook of cage-type collectors; Projekt Handbuch Erdwaermekoerbe. Dokumentation, Auslegung und Anwendungsbeispiele  

Energy Technology Data Exchange (ETDEWEB)

This final report for the Swiss Federal Office of Energy (SFOE) presents the results of a project that examined the use of cage-type ground-loop collectors used as the heat or cold source for heat-pump installations. The report describes the operating principle, functioning and application of such installations. Also, examples of installations are given and typical installations are documented. Simple rules for the dimensioning of the installations are presented. The suitability of such systems as an alternative to traditional ground loops and borehole heat exchangers for use in the heating systems of smaller single-family homes is discussed.

Bassetti, S.; Rohner, E.

2005-07-01

74

Standarized performance tests of collectors of solar thermal energy: A steel flat-plate collector with two transparent covers and a proprietary coating  

Science.gov (United States)

Basic test results of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator are given. The collector was tested over ranges of inlet temperature and flux level.

1976-01-01

75

The Oklahoma Field Test: Air-conditioning electricity savings from standard energy conservation measures, radiant barriers, and high-efficiency window air conditioners  

Energy Technology Data Exchange (ETDEWEB)

A field test Involving 104 houses was performed in Tulsa, Oklahoma, to measure the air-conditioning electricity consumption of low-income houses equipped with window air conditioners, the reduction in this electricity consumption attributed to the installation of energy conservation measures (ECMS) as typically installed under the Oklahoma Weatherization Assistance Program (WAP), and the reduction achieved by the replacement of low-efficiency window air conditioners with high-efficiency units and the installation of attic radiant barriers. Air-conditioning electricity consumption and indoor temperature were monitored weekly during the pre-weatherization period (June to September 1988) and post-weatherization period (May to September 1989). House energy consumption models and regression analyses were used to normalize the air-conditioning electricity savings to average outdoor temperature conditions and the pre-weatherization indoor temperature of each house. The following conclusions were drawn from the study: (1) programs directed at reducing air-conditioning electricity consumption should be targeted at clients with high consumption to improve cost effectiveness; (2) replacing low-efficiency air conditioners with high-efficiency units should be considered an option in a weatherization program directed at reducing air-conditioning electricity consumption; (3) ECMs currently being installed under the Oklahoma WAP (chosen based on effectiveness at reducing space-heating energy consumption) should continue to be justified based on their space-heating energy savings potential only; and (4) attic radiant barriers should not be included in the Oklahoma WAP if alternatives with verified savings are available or until further testing demonstrates energy savings or other benefits in this typo of housing.

Ternes, M.P.; Levins, W.P.

1992-08-01

76

Standardized performance tests of collectors of solar thermal energy-a flat-plate collector with a single-tube serpentine flow distribution  

Science.gov (United States)

This preliminary data report gives basic test results of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and coolant flow rates. Collector efficienty is correlated in terms of inlet temperature and flux level.

Johnson, S.

1976-01-01

77

Solar collector manufacturing activity, 1990  

International Nuclear Information System (INIS)

The Solar Collector Manufacturing Activity 1990 report prepared by the Energy Information Administration (EIA) presents summary and detailed data provided by domestic manufacturers on shipments of solar thermal collectors and photovoltaic cells and modules. Summary data on solar thermal collector shipments are presented for the period 1974 through 1990. Summary data on photovoltaic cell and module shipments are presented for the period 1982 through 1990. Detailed information for solar thermal collectors and photovoltaic cells and modules are presented for 1990

78

Design and Control of Hydronic Radiant Cooling Systems  

Science.gov (United States)

Improving energy efficiency in the Heating Ventilation and Air conditioning (HVAC) systems in buildings is critical to achieve the energy reduction in the building sector, which consumes 41% of all primary energy produced in the United States, and was responsible for nearly half of U.S. CO2 emissions. Based on a report by the New Building Institute (NBI), when HVAC systems are used, about half of the zero net energy (ZNE) buildings report using a radiant cooling/heating system, often in conjunction with ground source heat pumps. Radiant systems differ from air systems in the main heat transfer mechanism used to remove heat from a space, and in their control characteristics when responding to changes in control signals and room thermal conditions. This dissertation investigates three related design and control topics: cooling load calculations, cooling capacity estimation, and control for the heavyweight radiant systems. These three issues are fundamental to the development of accurate design/modeling tools, relevant performance testing methods, and ultimately the realization of the potential energy benefits of radiant systems. Cooling load calculations are a crucial step in designing any HVAC system. In the current standards, cooling load is defined and calculated independent of HVAC system type. In this dissertation, I present research evidence that sensible zone cooling loads for radiant systems are different from cooling loads for traditional air systems. Energy simulations, in EnergyPlus, and laboratory experiments were conducted to investigate the heat transfer dynamics in spaces conditioned by radiant and air systems. The results show that the magnitude of the cooling load difference between the two systems ranges from 7-85%, and radiant systems remove heat faster than air systems. For the experimental tested conditions, 75-82% of total heat gain was removed by radiant system during the period when the heater (simulating the heat gain) was on, while for air system, 61-63% were removed. From a heat transfer perspective, the differences are mainly because the chilled surfaces directly remove part of the radiant heat gains from a zone, thereby bypassing the time-delay effect caused by the interaction of radiant heat gain with non-active thermal mass in air systems. The major conclusions based on these findings are: 1) there are important limitations in the definition of cooling load for a mixing air system described in Chapter 18 of ASHRAE Handbook of Fundamentals when applied to radiant systems; 2) due to the obvious mismatch between how radiant heat transfer is handled in traditional cooling load calculation methods compared to its central role in radiant cooling systems, this dissertation provides improvements for the current cooling load calculation method based on the Heat Balance procedure. The Radiant Time Series method is not appropriate for radiant system applications. The findings also directly apply to the selection of space heat transfer modeling algorithms that are part of all energy modeling software. Cooling capacity estimation is another critical step in a design project. The above mentioned findings and a review of the existing methods indicates that current radiant system cooling capacity estimation methods fail to take into account incident shortwave radiation generated by solar and lighting in the calculation process. This causes a significant underestimation (up to 150% for some instances) of floor cooling capacity when solar load is dominant. Building performance simulations were conducted to verify this hypothesis and quantify the impacts of solar for different design scenarios. A new simplified method was proposed to improve the predictability of the method described in ISO 11855 when solar radiation is present. The dissertation also compares the energy and comfort benefits of the model-based predictive control (MPC) method with a fine-tuned heuristic control method when applied to a heavyweight embedded surface system. A first order dynamic model of a radiant slab system was developed for impl

Feng, Jingjuan

79

Assessment of Energy, Environmental and Economic Performance of a Solar Desiccant Cooling System with Different Collector Types  

Directory of Open Access Journals (Sweden)

Full Text Available Desiccant-based air handling units can achieve reductions in greenhouse gas emissions and energy savings with respect to conventional air conditioning systems. Benefits are maximized when they interact with renewable energy technologies, such as solar collectors. In this work, experimental tests and data derived from scientific and technical literature are used to implement a model of a solar desiccant cooling system, considering three different collector technologies (air, flat-plate and evacuated collectors. Simulations were then performed to compare the energy, environmental and economic performance of the system with those of a desiccant-based unit where regeneration thermal energy is supplied by a natural gas boiler, and with those of a conventional air-handling unit. The only solution that allows achieving the economic feasibility of the solar desiccant cooling unit consists of 16 m2 of evacuated solar collectors. This is able to obtain, with respect to the reference system, a reduction of primary energy consumption and of the equivalent CO2 emissions of 50.2% and 49.8%, respectively, but with a payback time of 20 years.

Giovanni Angrisani

2014-10-01

80

Building Space Heating with a Solar-Assisted Heat Pump Using Roof-Integrated Solar Collectors  

Directory of Open Access Journals (Sweden)

Full Text Available A solar assisted heat pump (SAHP system was designed by using a roof-integrated solar collector as the evaporator, and then it was demonstrated to provide space heating for a villa in Tianjin, China. A building energy simulation tool was used to predict the space heating load and a three dimensional theoretical model was established to analyze the heat collection performance of the solar roof collector. A floor radiant heating unit was used to decrease the energy demand. The measurement results during the winter test period show that the system can provide a comfortable living space in winter, when the room temperature averaged 18.9 °C. The average COP of the heat pump system is 2.97 and with a maximum around 4.16.

Zhiyong Yang

2011-03-01

81

Think GREEN - Utilizing Renewable Solar Energy  

Science.gov (United States)

Solar energy is radiant energy that is produced by the Sun. Every day the Sun radiates an enormous amount of energy. How much solar energy a place on Earth receives depends on several conditions. In this lesson, students will explore real NASA satellite data for energy from the Sun and cloud cover for their area to determine if they can harness this solar energy, a renewable energy source, by using a solar collector. They will develop skills in graphing and reading graphs.

82

Characterization of radiant emitters used in food processing.  

Science.gov (United States)

Radiant emissions from short, medium, and long wavelength thermal radiant emitter systems typically used for food processing applications were quantified. Measurements included heat flux intensity, emitter surface temperature, and spectral wavelength distribution. Heat flux measurements were found highly dependent on the incident angle and the distance from the emitter facing. The maximum flux measured was 5.4 W/cm2. Emitter surface temperature measurements showed that short wavelength radiant systems had the highest surface temperature and greatest thermal efficiency. The emitter spectral distributions showed that radiant emitter systems had large amounts of far infrared energy emission greater than 3 microm when compared to theoretical blackbody curves. The longer wavelength energy would likely cause increased surface heating for most high moisture content food materials. PMID:15323107

Lloyd, B J; Farkas, B E; Keener, K M

2003-01-01

83

Satellite Collectors of Solar Energy for Earth and Colonized Planet Habitats  

Science.gov (United States)

Summary An array of 55,000 40-foot antennas can generate from the rays of the Sun enough electrical power to replace 50 The economic potential is huge. There are new industries that will only grow and there are different ways to collect solar energy, including wind power. The energy sources we rely on for the most part are finite - fossil fuels, coal, oil and natural gas are all limited in supply. The cost will only continue to rise as demand increases. The time of global economic crossover between the EU, Asia Pacific and North America is coming within less than five years. The biggest opportunity for solar energy entrepreneurs would seem to be in municipal contracting where 1500 40-foot stacking antennas can be hooked into a grid to power an entire city. The antenna can generate 45 kilowatts of energy, enough to satisfy the electrical needs 7x24 of ten to twenty homes. It is possible to design and build 35-by-80-foot pedestals that track the sun from morning until night to provide full efficiency. A normal solar cell looks in the sky for only four or five hours of direct sunlight. Fabrication of these pedestals would sell for USD 50, 000-70,000 each. The solar heat collected by the antennas can be bounced into a Stirling engine, creating electricity at a focal point. Water can be heated by running through that focal point. In addition, salt water passing through the focal point can be desalinated, and since the antenna can generate up to 2,000 degrees of heat at the focal point. The salt water passing through the focal point turns to steam, which separates the salt and allows the steam to be turned into fresh drinking water. Collector energy can be retained in betavoltaics which uses semiconductors to capture energy from radioactive materials and turn it into usable electricity for automobiles. In a new battery, the silicon wafers in the battery are etched with a network of deep pores. These pores vastly increase the exposure surface area of the silicon, allowing it to absorb more energy and making the antenna collector 20 times more efficient than planar designs. A tracking pedestal powered by betavoltaics can follow the sun. With a 500-sun photovoltaic cell underneath a Fresnal lens magnifies and distributes the sun's energy at 500 times. Primary results and the main conclusions This idea is revolutionary and utilizes satellite tracking abilities to follow the sun, maintaining a constant energy source that can reach 700 to 800 degrees. This technology will have many applications, from instant fresh water in the form of steam to the use of fiber optics to filter natural light through a building. With the direction of the oil and energy costs continuing to spiral upward, there has been recent emphasis on alternative energy that is transmitted from space. Satellite antenna manufacturers can move quickly to production and create a revolution in sustainable energy that was never thought of before. The efforts of the United States, Russia, China, and India to colonize the Moon and Mars would be greatly enhanced by use of satellite solar collectors and betavoltaics electrical energy technologies for the colonies' habitats. Introduction This study was undertaken for the Global environment is in a crisis. The rich oil producing countries of Russia, Saudi Arabia, Venezuela, and Africa, have been at war to gain monopoly power and to restrict the space based explorations of the solar system. The physics of solar energy transmission to electrical mechanical energy is unique in improving the economies of the entire community of Nations. It is easy to produce satellite antennas, thus, satellite antennas can now be used as solar panels which can generate free power from the sun by converting sunlight to electricity. Solar Panels require no moving parts; have zero emissions, and no maintenance. These antennas will revolutionize the use of solar rays from the sun to benefit a global grid. These "collectors of free energy" are able to harness solar energy for thermal heating, desalination, lighting, and electricity. Further,

Kusiolek, Richard

84

Analysis of potential energy, economic and environmental savings in residential buildings: Solar collectors combined with microturbines  

International Nuclear Information System (INIS)

Highlights: ? Centralization of energy systems for a group of buildings improves profitability. ? Thermal solar systems are economically interesting even in low radiation locations. ? Regulations currently in force determine the feasibility of high efficiency energy systems. - Abstract: This paper presents an analysis of a combined solar-cogeneration installation for providing energy services in a set of four residential buildings. Different configurations as regards the number of collectors and their orientation, the number of buildings grouped together, the type of microturbines used in the cogeneration system and their daily and annual operating period are studied from the legal, economic and environmental perspectives. The installation that fulfils the minimum requirements of the solar system coverage and the cogeneration system efficiency currently in force, and simultaneously leads to the highest energy, economic and environmental savings is the one that integrates both technologies and centralises the installation for the four buildings together. A payback period lower than 8 years is obtained that makes this investment recommendable, but it is also concluded that maintaining the existing subsidies for these technologies and lowering the costs of the equipment, are essential factors to ensure the feasibility of this type of installations

85

Coloration Determination of Spectral Darkening Occurring on a Broadband Earth Observing Radiometer: Application to Clouds and the Earth's Radiant Energy System (CERES)  

Science.gov (United States)

It is estimated that in order to best detect real changes in the Earth s climate system, space based instrumentation measuring the Earth Radiation Budget (ERB) must remain calibrated with a stability of 0.3% per decade. Such stability is beyond the specified accuracy of existing ERB programs such as the Clouds and the Earth s Radiant Energy System (CERES, using three broadband radiometric scanning channels: the shortwave 0.3 - 5microns, total 0.3. > 100microns, and window 8 - 12microns). It has been shown that when in low earth orbit, optical response to blue/UV radiance can be reduced significantly due to UV hardened contaminants deposited on the surface of the optics. Since typical onboard calibration lamps do not emit sufficient energy in the blue/UV region, this darkening is not directly measurable using standard internal calibration techniques. This paper describes a study using a model of contaminant deposition and darkening, in conjunction with in-flight vicarious calibration techniques, to derive the spectral shape of darkening to which a broadband instrument is subjected. Ultimately the model uses the reflectivity of Deep Convective Clouds as a stability metric. The results of the model when applied to the CERES instruments on board the EOS Terra satellite are shown. Given comprehensive validation of the model, these results will allow the CERES spectral responses to be updated accordingly prior to any forthcoming data release in an attempt to reach the optimum stability target that the climate community requires.

Matthews, Grant; Priestley, Kory; Loeb, Norman G.; Loukachine, Konstantin; Thomas, Susan; Walikainen, Dale; Wielicki, Bruce A.

2006-01-01

86

Thermal performance evaluation of Solar Energy Products Company (SEPCO) 'Soloron' collector tested outdoors  

Science.gov (United States)

The test article, Model EF-212, Serial Nr. 002, is a single glazed collector with a nonselective absorber plate, using flowing air as the heat transfer medium. The absorber plate and box frame are aluminum and the insulation is one inch isocyanurate foam board with thermal conductivity of 0.11 (BTU/sq ft Hr0/ft.) The tests included the following. (1) time constant test, (2) collector efficiency test, (3) collector stagnation test, (4) incident angle modifier test, (5) load test, (6) weathering test, and (7) absorber plate optical properties test. The results of these tests are tabulated, graphed, or otherwise recorded.

Chiou, J., Sr.

1977-01-01

87

On-orbit stability and performance of the Clouds and Earth's Radiant Energy System (CERES) instrument sensors onboard the Aqua and Terra Spacecraft  

Science.gov (United States)

The Clouds and Earth's Radiant Energy System (CERES) instruments onboard the Terra and Aqua spacecraft are part of the NASA Earth Observing System (EOS) constellation to make long-term observations of the earth. CERES measures the earth-reflected shortwave energy as well as the earth-emitted thermal energy, which are two components of the earth's radiation energy budget. These measurements are made by five instruments- Flight Models (FM) 1 and 2 onboard Terra, FMs 3 and 4 onboard Aqua and FM5 onboard Suomi NPP. Each instrument comprises three sensors that measure the radiances in different wavelength bands- a shortwave sensor that measures in the 0.3 to 5 micron band, a total sensor that measures all the incident energy (0.3-200 microns) and a window sensor that measures the water-vapor window region of 8 to 12 microns. The stability of the sensors is monitored through on-orbit calibration and validation activities. On-orbit calibration is carried out using the Internal Calibration Module (ICM) that consists of a tungsten lamp, blackbodies, and a solar diffuser known as the Mirror Attenuator Mosaic (MAM). The ICM calibration provides information about the stability of the sensors' broadband radiometric gains on-orbit. Several validation studies are conducted in order to monitor the behavior of the instruments in various spectral bands. The CERES Edition-4 data products for FM1-FM4 incorporate the latest corrections to the sensor responses using the calibration techniques. In this paper, we present the on-orbit performance stability as well as some validation studies used in deriving the CERES Edition-4 data products from all four instruments.

Shankar, Mohan; Priestley, Kory; Smith, Nitchie; Thomas, Susan; Walikainen, Dale

2014-09-01

88

Estimate of Top-of-Atmosphere Albedo for a Molecular Atmosphere over Ocean using Clouds and the Earth's Radiant Energy System (CERES) Measurements  

Science.gov (United States)

The shortwave broadband albedo at the top of a molecular atmosphere over ocean between 40deg N and 40deg S is estimated using radiance measurements from the Clouds and the Earth's Radiant Energy System (CERES) instrument and the Visible Infrared Scanner (VIRS) aboard the Tropical Rainfall Measuring Mission (TRMM) satellite. The albedo monotonically increases from 0.059 at a solar zenith angle of 10deg to 0.107 at a solar zenith angle of 60deg. The estimated uncertainty in the albedo is 3.5 x 10(exp -3) caused by the uncertainty in CERES-derived irradiances, uncertainty in VIRS-derived aerosol optical thicknesses, variations in ozone and water vapor, and variations in surface wind speed. The estimated uncertainty is similar in magnitude to the standard deviation of 0.003 that is derived from 72 areas divided by 20deg latitude by 20deg longitude grid boxes. The empirically estimated albedo is compared with the modeled albedo using a radiative transfer model combined with an ocean surface bidirectional reflectivity model. The modeled albedo with standard tropical atmosphere is 0.061 and 0.111 at the solar zenith angles of 10deg and 60deg, respectively. This empirically estimated albedo can be used to estimate the direct radiative effect of aerosols at the top of the atmosphere over oceans.

Kato, S.; Loeb, N. G.; Rutledge, C. K.

2002-01-01

89

Clouds and the Earth's Radiant Energy System (CERES) algorithm theoretical basis document. volume 2; Geolocation, calibration, and ERBE-like analyses (subsystems 1-3)  

Science.gov (United States)

The theoretical bases for the Release 1 algorithms that will be used to process satellite data for investigation of the Clouds and Earth's Radiant Energy System (CERES) are described. The architecture for software implementation of the methodologies is outlined. Volume 2 details the techniques used to geolocate and calibrate the CERES scanning radiometer measurements of shortwave and longwave radiance to invert the radiances to top-of-the-atmosphere (TOA) and surface fluxes following the Earth Radiation Budget Experiment (ERBE) approach, and to average the fluxes over various time and spatial scales to produce an ERBE-like product. Spacecraft ephemeris and sensor telemetry are used with calibration coefficients to produce a chronologically ordered data product called bidirectional scan (BDS) radiances. A spatially organized instrument Earth scan product is developed for the cloud-processing subsystem. The ERBE-like inversion subsystem converts BDS radiances to unfiltered instantaneous TOA and surface fluxes. The TOA fluxes are determined by using established ERBE techniques. Hourly TOA fluxes are computed from the instantaneous values by using ERBE methods. Hourly surface fluxes are estimated from TOA fluxes by using simple parameterizations based on recent research. The averaging process produces daily, monthly-hourly, and monthly means of TOA and surface fluxes at various scales. This product provides a continuation of the ERBE record.

Wielicki, B. A. (Principal Investigator); Barkstrom, B. R. (Principal Investigator); Charlock, T. P.; Baum, B. A.; Green, R. N.; Minnis, P.; Smith, G. L.; Coakley, J. A.; Randall, D. R.; Lee, R. B., III

1995-01-01

90

3X compound parabolic concentrating (CPC) solar energy collector. Final technical report  

Energy Technology Data Exchange (ETDEWEB)

Chamberlain engineers designed a 3X compound parabolic concentrating (CPC) collector for the subject contract. The collector is a completely housed, 105.75 x 44.75 x 10.23-inch, 240-pound unit with six each evacuated receiver assemblies, a center manifold and a one-piece glass cover. A truncated version of a CPC trough reflector system and the General Electric Company tubular evacuated receiver have been integrated with a mass producible collector design suitable for operation at 250 to 450/sup 0/F. The key criterion for optimization of the design was minimization of the cost per Btu collected annually at an operating temperature of 400/sup 0/F. The reflector is a 4.1X design truncated to a total height of 8.0 inches with a resulting actual concentration ratio of 2.6 to 1. The manifold is an insulated area housing the fluid lines which connect the six receivers in series with inlet and outlet tubes extending from one side of the collector at the center. The reflectors are polished, anodized aluminum which are shaped by the roll form process. The housing is painted, galvanized steel, and the cover glass is 3/16-inch thick tempered, low iron glass. The collector requires four slope adjustments per year for optimum effectiveness. Chamberlain produced ten 3X CPC collectors for the subject contract. Two collectors were used to evaluate assembly procedures, six were sent to the project officer in Albuquerque, New Mexico, one was sent to Argonne National Laboratory for performance testing and one remained with the Company. A manufacturing cost study was conducted to estimate limited mass production costs, explore cost reduction ideas and define tooling requirements. The final effort discussed shows the preliminary design for application of a 3X CPC solar collector system for use in the Iowa State Capitol complex.

Ballheim, R.W.

1980-04-25

91

Vaillant starts production of solar collectors. Products on the basis of renewable energy are going strong; Vaillant startet Produktion von Solarkollektoren. Produkte auf Basis regenerativer Energien auf Wachstumskurs  

Energy Technology Data Exchange (ETDEWEB)

On 6 June 2008, the Vaillant group started production of solar collectors in their new factory at Gelsenkirchen. The company intends to buoy up its position in the fast-growing sector of renewable energy sources. (orig.)

Anon.

2008-07-15

92

Highlights of the solar total energy systems, distributed collector systems, and research and development projects. Semiannual review, 26-27 January 1976, Atlanta, Georgia  

Energy Technology Data Exchange (ETDEWEB)

The highlights of the ERDA Solar Thermal Branch Semiannual Review held in Atlanta, Georgia, on January 26-27, 1976, are presented. Status and plans for Total Energy Systems, Distributed Collectors, and Research and Development Projects are reviewed. (WHK)

Latta, A.F.

1976-03-26

93

Hybrid utilization of solar energy. Part 2. Performance analyses of heating system with air hybrid collector; Taiyo energy no hybrid riyo ni kansuru kenkyu. 2. Kuki shunetsu hybrid collector wo mochiita danbo system no seino hyoka  

Energy Technology Data Exchange (ETDEWEB)

For the effective utilization of solar energy at houses, a heating system using an air hybrid collector (capable of simultaneously performing heat collection and photovoltaic power generation). As the specimen house, a wooden house of a total floor area of 120m{sup 2} was simulated. Collected air is fanned into a crushed stone heat accumulator (capable of storing one day`s collection) or into a living room. The output of solar cell arrays is put into a heat pump (capable of handling a maximum hourly load of 36,327kJ/h) via an inverter so as to drive the fan (corresponding to average insolation on the heat collecting plate of 10.7MJ/hm{sup 2} and heat collecting efficiency of 40%), and shortage in power if any is supplied from the system interconnection. A hybrid collector, as compared with the conventional air collector, is lower in thermal efficiency but the merit that it exhibits with respect to power generation is far greater than what is needed to counterbalance the demerit. When the hybrid system is in heating operation, there is an ideal heat cycle of collection, accumulation, and radiation when the load is light, but the balance between accumulation and radiation is disturbed when the load is heavy. 4 refs., 8 figs., 3 tabs.

Yoshinaga, M.; Okumiya, M. [Nagoya University, Nagoya (Japan)

1996-10-27

94

Development and assessment of broadband surface albedo from Clouds and the Earth's Radiant Energy System Clouds and Radiation Swath data product  

Science.gov (United States)

We describe a method to determine broadband albedo globally over land viewed by the Clouds and the Earth's Radiant Energy System (CERES) scanning radiometers on board the TRMM, Terra, and Aqua satellites. This albedo is used as a surface boundary condition for a fast radiation transfer code in the Surface and Atmospheric Radiation Budget (SARB) subsystem of the CERES processing scheme. Cloudy sky surface albedo is estimated from derived clear sky values. Clear sky surface albedo is assessed by comparing the CERES/SARB-based surface albedo with the bidirectional reflectance distribution function (BRDF)-based surface albedo supplied by the MODIS land surfaces group. The SARB method employs broadband observations at the top of atmosphere (TOA) and assumes relative spectral shape of surface albedo. The MODIS group uses higher spatial resolution observations in several shortwave window channels to retrieve spectral surface albedos and then scales up to broadband surface albedo. Comparisons over snow-free land show good agreement between the two independent products on the scale of the CERES footprint. Biases run approximately 0.005 absolute or 0.02 relative with SARB albedo, generally lower than MODIS. We find little dependence on view geometry and slight functional dependence on aerosol optical depth. The value selected for a priori surface spectral albedo is important, but not critical, when retrieving broadband surface albedo with broadband TOA data. However, based on calculations, aerosol forcing to TOA flux changes in spectral albedo shape can affect aerosol forcing for as much as would a 15% absolute change in the original broadband surface albedo.

Rutan, David; Rose, Fred; Roman, Miguel; Manalo-Smith, Natividad; Schaaf, Crystal; Charlock, Tom

2009-04-01

95

Sensor performance of Clouds and the Earth's Radiant Energy System (CERES) instruments aboard EOS Terra and Aqua spacecraft based on post-launch calibration studies  

Science.gov (United States)

Clouds and the Earth's Radiant Energy System (CERES) instruments were designed to measure the reflected shortwave and emitted longwave radiances of the Earth's radiation budget and to investigate the cloud interactions with global radiances for the long-term monitoring of Earth's climate. The three scanning thermistor bolometers measure the broadband radiances in the shortwave (0.3 to 5.0 micrometer), total (0.3 to >100 micrometer) and 8 - 12 micrometer water vapor window regions. Four CERES instruments (Flight Models1 through 4) are flying aboard EOS Terra and Aqua platforms with two instruments aboard each spacecraft. The post launch calibration of CERES sensors are carried out using the internal calibration module (ICM) comprising of blackbody sources and quartz-halogen tungsten lamp, and a solar diffuser plate known as the Mirror Attenuator Mosaic (MAM). The ICM calibration results are instrumental in understanding the shift in CERES sensors' gains after launch from the pre-launch determined values. Several validation studies are also conducted with the CERES measurements to monitor the behavior of the sensors in various spectral regions. In addition to the broadband response changes derived from the on-board blackbody and the tungsten lamp, the shortwave and the total sensors show further drop in responsivity in the UV spectral region that were brought to light through validation studies. Further analyses were performed to correct for these response changes at all spectral regions. This paper reports the sensor response changes that were determined with the on-board calibration sources and the investigation of the additional factors that influence the performance of the CERES sensors in orbit.

Thomas, Susan; Priestley, K. J.; Hess, P. C.; Wilson, R. S.; Avery, M. A.; Walikainen, D. R.; Szewczyk, Z. P.; Cooper, D. L.; Shankar, M.

2009-08-01

96

Shenandoah parabolic dish solar collector  

Energy Technology Data Exchange (ETDEWEB)

The objectives of the Shenandoah, Georgia, Solar Total Energy System are to design, construct, test, and operate a solar energy system to obtain experience with large-scale hardware systems for future applications. This report describes the initial design and testing activities conducted to select and develop a collector that would serve the need of such a solar total energy system. The parabolic dish was selected as the collector most likely to maximize energy collection as required by this specific site. The fabrication, testing, and installation of the parabolic dish collector incorporating improvements identified during the development testing phase are described.

Kinoshita, G.S.

1985-01-01

97

Shenandoah parabolic dish solar collector  

Science.gov (United States)

The objectives of the Shenandoah, Georgia, Solar Total Energy System are to design, construct, test, and operate a solar energy system to obtain experience with large scale hardware systems for future applications. The initial design and testing activities conducted to select and develop a collector that would serve the need of such a solar total energy system are described. The parabolic dish was selected as the collector most likely to maximize energy collection as required by this specific site. The fabrication, testing, and installation of the parabolic dish collector incorporating improvements identified during the development testing phase are described.

Kinoshita, G. S.

1985-01-01

98

A search for space energy alternatives  

Science.gov (United States)

This paper takes a look at a number of schemes for converting radiant energy in space to useful energy for man. These schemes are possible alternatives to the currently most studied solar power satellite concept. Possible primary collection and conversion devices discussed include the space particle flux devices, solar windmills, photovoltaic devices, photochemical cells, photoemissive converters, heat engines, dielectric energy conversion, electrostatic generators, plasma solar collectors, and thermionic schemes. Transmission devices reviewed include lasers and masers.

Gilbreath, W. P.; Billman, K. W.

1978-01-01

99

Steady-state heat transfer in transversely heated porous media with application to focused solar energy collectors  

Science.gov (United States)

A fluid flowing in a porous medium heated transversely to the fluid flow is considered. This configuration is applicable to a focused solar energy collector for use in an electric power generating system. A fluidized bed can be regarded as a porous medium with special properties. The solutions presented are valid for describing the effectiveness of such a fluidized bed for collecting concentrated solar energy to heat the working fluid of a heat engine. Results indicate the advantage of high thermal conductivity in the transverse direction and high operating temperature of the porous medium.

Nichols, L. D.

1976-01-01

100

Alternative energy sources IV; Proceedings of the Fourth Miami International Conference, Miami Beach, FL, December 14-16, 1981. Volume 1 - Solar Collectors Storage  

Science.gov (United States)

Aspects of solar measurements, solar collectors, selective coatings, thermal storage, phase change storage, and heat exchangers are discussed. The analysis and testing of flat-plate solar collectors are addressed. The development and uses of plastic collectors, a solar water heating system, solar energy collecting oil barrels, a glass collector panel, and a two-phase thermosyphon system are considered. Studies of stratification in thermal storage, of packed bed and fluidized bed systems, and of thermal storage in solar towers, in wall passive systems, and in reversible chemical reactions are reported. Phase change storage by direct contact processes and in residential solar space heating and cooling is examined, as are new materials and surface characteristics for solar heat storage. The use of R-11 and Freon-113 in heat exchange is discussed. No individual items are abstracted in this volume

Veziroglu, T. N.

1982-10-01

101

Optical Sensors for Planetary Radiant Energy (OSPREy): Calibration and Validation of Current and Next-Generation NASA Missions  

Science.gov (United States)

A principal objective of the Optical Sensors for Planetary Radiance Energy (OSPREy) activity is to establish an above-water radiometer system as a lower-cost alternative to existing in-water systems for the collection of ground-truth observations. The goal is to be able to make high-quality measurements satisfying the accuracy requirements for the vicarious calibration and algorithm validation of next-generation satellites that make ocean color and atmospheric measurements. This means the measurements will have a documented uncertainty satisfying the established performance metrics for producing climate-quality data records. The OSPREy approach is based on enhancing commercial-off-the-shelf fixed-wavelength and hyperspectral sensors to create hybridspectral instruments with an improved accuracy and spectral resolution, as well as a dynamic range permitting sea, Sun, sky, and Moon observations. Greater spectral diversity in the ultraviolet (UV) will be exploited to separate the living and nonliving components of marine ecosystems; UV bands will also be used to flag and improve atmospheric correction algorithms in the presence of absorbing aerosols. The short-wave infrared (SWIR) is expected to improve atmospheric correction, because the ocean is radiometrically blacker at these wavelengths. This report describes the development of the sensors, including unique capabilities like three-axis polarimetry; the documented uncertainty will be presented in a subsequent report.

Hooker, Stanford B.; Bernhard, Germar; Morrow, John H.; Booth, Charles R.; Comer, Thomas; Lind, Randall N.; Quang, Vi

2012-01-01

102

Thermal Modeling of a Hybrid Thermoelectric Solar Collector with a Compound Parabolic Concentrator  

Science.gov (United States)

In this study radiant light from the sun is used by a hybrid thermoelectric (TE) solar collector and a compound parabolic concentrator (CPC) to generate electricity and thermal energy. The hybrid TE solar collector system described in this report is composed of transparent glass, an air gap, an absorber plate, TE modules, a heat sink to cool the water, and a storage tank. Incident solar radiation falls on the CPC, which directs and reflects the radiation to heat up the absorber plate, creating a temperature difference across the TE modules. The water, which absorbs heat from the hot TE modules, flows through the heat sink to release its heat. The results show that the electrical power output and the conversion efficiency depend on the temperature difference between the hot and cold sides of the TE modules. A maximum power output of 1.03 W and a conversion efficiency of 0.6% were obtained when the temperature difference was 12°C. The thermal efficiency increased as the water flow rate increased. The maximum thermal efficiency achieved was 43.3%, corresponding to a water flow rate of 0.24 kg/s. These experimental results verify that using a TE solar collector with a CPC to produce both electrical power and thermal energy seems to be feasible. The thermal model and calculation method can be applied for performance prediction.

Lertsatitthanakorn, C.; Jamradloedluk, J.; Rungsiyopas, M.

2013-07-01

103

Magnetic droplet radiator collectors  

International Nuclear Information System (INIS)

Radiating heat via a droplet sheet offers a light weight, easily deployable means of rejecting energy from a spacecraft. Uncertainties in the trajectory of the droplets and splashing in the droplet collector can lead to unacceptable coolant mass losses. A study conducted at Brookhaven National Laboratory has investigated using ferrofluids with magnetic collectors to reduce these potential losses. Streams of ferrofluid droplets have been produced through 100 and 150 ?m orifices. These droplets have been accelerated in excess of five ''g's'' using permanent magnets and have been observed to behave stably and remain intact. Preliminary testing with thirty-seven parallel streams indicates that, except for collector splashing, multiple streams behave, from a fluid's viewpoint, like single streams. Single drops impacting under conditions known to produce satellite drops following impact were observed for varying magnetic conditions. At roughly one kilogauss, all incoming material would be captured under weightless conditions. Rebounding material tends to flow along lines of magnetic flux. Trade studies indicate that a range of conditions exists over which magnetic collections offer a weight advantage over a heat pipe radiator or droplet radiator with a large collector. 11 figs

104

Controlled Production of Sub-Radiant States of a Diatomic Molecule in an Optical Lattice  

CERN Document Server

We report successful production of sub-radiant states of a two-atom system in a three-dimensional optical lattice starting from doubly occupied sites in a Mott insulator phase of a quantum gas of atomic ytterbium. We can selectively produce either sub-radiant 1g state or super-radiant 0u state by choosing the excitation laser frequency. The inherent weak excitation rate for the sub-radiant 1g state is overcome by the increased atomic density due to the tight-confinement in a three-dimensional optical lattice. Our experimental measurements of binding energies, linewidth, and Zeeman shift confirm observation of sub-radiant levels of the 1g state of the Yb_2 molecule.

Takasu, Yosuke; Takahashi, Yoshiro; Borkowski, Mateusz; Ciury?o, Roman; Julienne, Paul S

2012-01-01

105

Solar thermal collectors using planar reflector  

Science.gov (United States)

Specular reflectors have been used successfully with flat-plate collectors to achieve exceptionally high operating temperatures and high delivered energy per unit collector area. Optimal orientation of collectors and reflectors can result in even higher performance with an improved relationship between energy demand and supply. This paper reports on a study providing first order optimization of collector-reflector arrays in which single- and multiple-faceted reflectors in fixed or singly adjustable configurations provide delivered energy maxima in either summer or winter.

Espy, P. N.

1978-01-01

106

Meteor radiant mapping with MU radar  

Science.gov (United States)

The radiant point mapping of meteor showers with the MU radar by using a modified mapping method originally proposed by Morton and Jones (1982) was carried out. The modification is that each meteor echo was weighted by using the beam pattern of the radar system. A preliminary result of the radiant point mapping of the Geminids meteor shower in 1989 is presented.

Watanabe, Jun-Ichi; Nakamura, Tsuko; Tsuda, T.; Tsutsumi, M.; Miyashita, A.; Yoshikawa, M.

1992-01-01

107

Field experiments and analyses on a hybrid solar collector  

Energy Technology Data Exchange (ETDEWEB)

This paper describes the effectiveness of a hybrid solar collector that generates both electric power and heat. Experiments and analyses were conducted on power and heat generation characteristics of the hybrid solar collector. First, experiments under constant supply temperature of brine were made and it was found that conversion efficiency ranged from 10% to 13%, and that collector efficiencies at 20 and 40{sup o}C brine temperature were from 40% to 50% and approximately 20%, respectively. Second, the efficiency of the hybrid solar collector was compared to those of a photovoltaic and a solar collector and it was clarified that the hybrid collector had an advantage in terms of exergy efficiency, though there is some lowering of collector efficiency. Evaluation of annual energy balance of hybrid solar collectors installed on a low energy house at Hokkaido University proved the hybrid solar collectors to have a high degree of feasibility. (author)

Saitoh, Hisashi; Hamada, Yasuhiro; Kubota, Hideki; Nakamura, Makoto; Ochifuji, Kiyoshi; Yokoyama, Shintaro; Nagano, Katsunori [Hokkaido University, Sapporo (Japan). Graduate School of Engineering

2003-11-01

108

Standard performance tests of collectors of solar thermal energy: A selectively coated, flat-plate copper collector with one transparent cover and a tube-to-tube spacing of 3-7/8 inches  

Science.gov (United States)

Basic test results are given of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes, and coolant flow rates. Collector efficiency is correlated in terms of inlet temperature and flux level.

1976-01-01

109

Standardized performance tests of collectors of solar thermal energy: A selectively coated, flat-plate copper collector with one transparent cover and a tube-to-tube spacing of 5 5/8 inches  

Science.gov (United States)

This preliminary data report gives basic test results of a flat-plate solar collector whose performance was determined in the NASA-Lewis solar simulator. The collector was tested over ranges of inlet temperatures, fluxes and coolant flow rates. Collector efficiency is correlated in terms of inlet temperature and flux level.

1976-01-01

110

Advanced radiant combustion system. Final report, September 1989--September 1996  

Energy Technology Data Exchange (ETDEWEB)

Results of the Advanced Radiant Combustion System (ARCS) project are presented in this report. This work was performed by Alzeta Corporation as prime contractor under a contract to the U.S. Department of Energy Office of Industrial Technologies as part of a larger DOE program entitled Research Program for Advanced Combustion Systems. The goals of the Alzeta ARCS project were to (a) Improve the high temperature performance characteristics of porous surface ceramic fiber burners, (b) Develop an Advanced Radiant Combustion System (ARCS) that combines combustion controls with an advanced radiant burner, and (c) Demonstrate the advanced burner and controls in an industrial application. Prior to the start of this project, Alzeta had developed and commercialized a porous surface radiant burner, the Pyrocore{trademark} burner. The product had been commercially available for approximately 5 years and had achieved commercial success in a number of applications ranging from small burners for commercial cooking equipment to large burners for low temperature industrial fluid heating applications. The burner was not recommended for use in applications with process temperatures above 1000{degrees}F, which prevented the burner from being used in intermediate to high temperature processes in the chemical and petroleum refining industries. The interest in increasing the maximum use temperature of the burner was motivated in part by a desire to expand the number of applications that could use the Pyrocore product, but also because many of the fluid sensitive heating applications of interest would benefit from the distributed flux characteristic of porous surface burners. Background information on porous surface radiant burners, and a discussion of advantages that would be provided by an improved product, are presented in Section 2.

Sullivan, J.D.; Carswell, M.G.; Long, F.S.

1996-09-01

111

Energy and economic assessment of desiccant cooling systems coupled with single glazed air and hybrid PV/thermal solar collectors for applications in hot and humid climate  

Energy Technology Data Exchange (ETDEWEB)

This paper presents a detailed analysis of the energy and economic performance of desiccant cooling systems (DEC) equipped with both single glazed standard air and hybrid photovoltaic/thermal (PV/t) collectors for applications in hot and humid climates. The use of 'solar cogeneration' by means of PV/t hybrid collectors enables the simultaneous production of electricity and heat, which can be directly used by desiccant air handling units, thereby making it possible to achieve very energy savings. The present work shows the results of detailed simulations conducted for a set of desiccant cooling systems operating without any heat storage. System performance was investigated through hourly simulations for different systems and load combinations. Three configurations of DEC systems were considered: standard DEC, DEC with an integrated heat pump and DEC with an enthalpy wheel. Two kinds of building occupations were considered: office and lecture room. Moreover, three configurations of solar-assisted air handling units (AHU) equipped with desiccant wheels were considered and compared with standard AHUs, focusing on achievable primary energy savings. The relationship between the solar collector's area and the specific primary energy consumption for different system configurations and building occupation patterns is described. For both occupation patterns, sensitivity analysis on system performance was performed for different solar collector areas. Also, this work presents an economic assessment of the systems. The cost of conserved energy and the payback time were calculated, with and without public incentives for solar cooling systems. It is worth noting that the use of photovoltaics, and thus the exploitation of related available incentives in many European countries, could positively influence the spread of solar air cooling technologies (SAC). An outcome of this work is that SAC systems equipped with PV/t collectors are shown to have better performance in terms of primary energy saving than conventional systems fed by vapour compression chillers and coupled with PV cells. All SAC systems present good figures for primary energy consumption. The best performances are seen in systems with integrated heat pumps and small solar collector areas. The economics of these SAC systems at current equipment costs and energy prices are acceptable. They become more interesting in the case of public incentives of up to 30% of the investment cost (Simple Payback Time from 5 to 10 years) and doubled energy prices. (author)

Beccali, Marco; Finocchiaro, Pietro; Nocke, Bettina [Universita degli Studi di Palermo, Palermo (Italy)

2009-10-15

112

Radiant cooling in US office buildings: Towards eliminating the perception of climate-imposed barriers  

Energy Technology Data Exchange (ETDEWEB)

Much attention is being given to improving the efficiency of air-conditioning systems through the promotion of more efficient cooling technologies. One such alternative, radiant cooling, is the subject of this thesis. Performance information from Western European buildings equipped with radiant cooling systems indicates that these systems not only reduce the building energy consumption but also provide additional economic and comfort-related benefits. Their potential in other markets such as the US has been largely overlooked due to lack of practical demonstration, and to the absence of simulation tools capable of predicting system performance in different climates. This thesis describes the development of RADCOOL, a simulation tool that models thermal and moisture-related effects in spaces equipped with radiant cooling systems. The thesis then conducts the first in-depth investigation of the climate-related aspects of the performance of radiant cooling systems in office buildings. The results of the investigation show that a building equipped with a radiant cooling system can be operated in any US climate with small risk of condensation. For the office space examined in the thesis, employing a radiant cooling system instead of a traditional all-air system can save on average 30% of the energy consumption and 27% of the peak power demand due to space conditioning. The savings potential is climate-dependent, and is larger in retrofitted buildings than in new construction. This thesis demonstrates the high performance potential of radiant cooling systems across a broad range of US climates. It further discusses the economics governing the US air-conditioning market and identifies the type of policy interventions and other measures that could encourage the adoption of radiant cooling in this market.

Stetiu, C.

1998-01-01

113

Solar thermal collector  

OpenAIRE

A solar thermal collector is a solar collector designed to collect heat by absorbing sunlight. The actuality of sun collectors today is unquestionable. They allow to heat dwellings, industrial, commercial buildings, and also to provide a hot water-supply in them. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/13475

?????, ???????? ?????????; ?????, ???????? ??????????; Mikhno, Svitlana Vasylivna; Trokhimenko, A.

2011-01-01

114

Exergy metrication of radiant panel heating and cooling with heat pumps  

International Nuclear Information System (INIS)

Highlights: ? Rational Exergy Management Model analytically relates heat pumps and radiant panels. ? Heat pumps driven by wind energy perform better with radiantpanels. ? Better CO2 mitigation is possible with wind turbine, heat pump, radiant panel combination. ? Energy savings and thermo-mechanical performance are directly linked to CO2 emissions. - Abstract: Radiant panels are known to be energy efficient sensible heating and cooling systems and a suitable fit for low-exergy buildings. This paper points out the little known fact that this may not necessarily be true unless their low-exergy demand is matched with low-exergy waste and alternative energy resources. In order to further investigate and metricate this condition and shed more light on this issue for different types of energy resources and energy conversion systems coupled to radiant panels, a new engineering metric was developed. Using this metric, which is based on the Rational Exergy Management Model, true potential and benefits of radiant panels coupled to ground-source heat pumps were analyzed. Results provide a new perspective in identifying the actual benefits of heat pump technology in curbing CO2 emissions and also refer to IEA Annex 49 findings for low-exergy buildings. Case studies regarding different scenarios are compared with a base case, which comprises a radiant panel system connected to a natural gas-fired condensing boiler in heating and a grid powe boiler in heating and a grid power-driven chiller in cooling. Results show that there is a substantial CO2 emission reduction potential if radiant panels are optimally operated with ground-source heat pumps driven by renewable energy sources, or optimally matched with combined heat and power systems, preferably running on alternative fuels.

115

Performance of an absorbing concentrating solar collectors  

International Nuclear Information System (INIS)

This paper reports on a comparison of the efficiency of an absorbing fluid parabolic trough concentrating solar collector and a traditional concentrating collector that was made. In the absorbing fluid collector, black liquid flows through a glass tube absorber while the same black liquid flows through a selective black coated copper tube absorber while the same black fluid flows through a selective black coated copper tube absorber in the traditional collector. After a careful study of the properties of available black liquids, a mixture of water and black ink was chosen as the black absorbing medium or transfer fluid. In the black liquid glass collector there is a slightly improved efficiency based on beam radiation as a result of the direct absorption process and an increase in the effective transmittance absorptance. At worst the efficiency of this collector equals that of the traditional concentrating collector when the efficiency is based on total radiation. The collector's reflecting surfaces were made of aluminum sheet, parabolic line focus and with cylindrical receivers. The ease of manufacture and reduced cost per unit energy collected, in addition to the clean and pollution free mode of energy conversion, makes it very attractive

116

Study of a biogas digester feed in energy by a solar-water heating collector  

International Nuclear Information System (INIS)

The socio-economic development which occurred to the XIXE and XXE centuries would have been impossible without energy. Indeed coal, oil, the nature gas and various other sources of energy were the world engine of the economy. Currently, energy is available in great quantity and remains relatively cheap. It makes it possible to many populations to enjoy very high levels of comfort, productivity and mobility. The access to these great quantities of energy and their exploitation is however unequally distributed between the areas and the countries. In Algeria in spite of the high contents in hydrocarbons, the supply fossil fuels (oil, natural gas) remains one of the major problems of the wedged areas and more particularly the mountainous areas and those of the south, which generated a consumption increased out of wood, a thorough degradation of the forests, an erosion of the grounds and a deterioration of the climate and environment. To meet the requirements in energy for our country, in order to ensure its perennity, to appreciably reduce local pollution and the effect of greenhouse, for the safeguarding of the environment, the prospecting and the development of new sources of energy were in particular undertaken the energy of the biomass and more precisely that provided by biogas. This largely available renewable energy, inexpensive and non-polluting in used to supplement non-renewable fossil energy. Energy production starting from the organic matt production starting from the organic matter of various origins: animal manure, under products of the food industry, mud of the stations of purification, household refuse..., by means of processes of anaerobic digestion in suitable digesters (for bio-methane production), will allow a better management of waste. a safeguarding of the environment and a development as well as a diversification of the energy resources (alternative energies). In addition, this organic matter, at the local level, will make it possible to produce energy at lower cost for cooking. the heating, the lighting and manure with high fertilising potential (stabilised mud) like amendments for the arable lands. The production of biogas could be regarded as an economic solution, decentralised and ecological with these problems through energy autonomy and a durable agricultural development of the rural zones. The bio-methane remains an energy ignored in Algeria, that in spite of several attempts at use which were undertaken since the Forties and even if it does not form part of our sociological cultural and economic traditions, it must represent the best solution to the already mentioned problems. Our study propose to produce bio-methane starting from the animal manure (dung of cows). For that an experimental device was designed and carried out. It consists of digester of 800 litters, of a gas meter bell of 600 litters, of a device of heating applied with a solar-fired heater which ensures a mesophile temperature to him and of a system of agitation of the substrate. The experimental study made it possible to optimize the process of production, for a domestic application and also to develop a system temperature control required at the entry of digester ranging between 25 and 40 degree centigrade. The model is quasi-autonomous. The achievement of this objective of research will make it possible, as we hope for it, to lay down a policy of digester installation of on a national scale.(Author)

117

Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth's Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part 1; Methodology  

Science.gov (United States)

Clouds and the Earth s Radiant Energy System (CERES) investigates the critical role that clouds and aerosols play in modulating the radiative energy flow within the Earth-atmosphere system. CERES builds upon the foundation laid by previous missions, such as the Earth Radiation Budget Experiment, to provide highly accurate top-of-atmosphere (TOA) radiative fluxes together with coincident cloud and aerosol properties inferred from high-resolution imager measurements. This paper describes the method used to construct empirical angular distribution models (ADMs) for estimating shortwave, longwave, and window TOA radiative fluxes from CERES radiance measurements on board the Tropical Rainfall Measuring Mission satellite. To construct the ADMs, multiangle CERES measurements are combined with coincident high-resolution Visible Infrared Scanner measurements and meteorological parameters from the European Centre for Medium-Range Weather Forecasts data assimilation product. The ADMs are stratified by scene types defined by parameters that have a strong influence on the angular dependence of Earth's radiation field at the TOA. Examples of how the new CERES ADMs depend upon the imager-based parameters are provided together with comparisons with existing models.

Loeb, N. G.; Smith, N. M.; Kato, S.; Miller, W. F.; Gupta, S. K.; Minnis, P.; Wielicki, B. A.

2003-01-01

118

Solar energy in double-pack? Hybrid collectors; Sonne im Doppelpack? Hybridkollektoren  

Energy Technology Data Exchange (ETDEWEB)

The scarce roof space could be utilized more efficient by means of modules which supply electricity as well as thermal energy for the generation of hot water or heating processes. Nethertheless, these solar modules do not harmonize optimally. Thus, the so-called hybrid technology prevails only hesitantly.

Anon.

2012-07-01

119

Hierarchic control of the production of energy by means of plants of distributed solar collectors; Control jerarquico de la produccion de energia mediante plantas de colectores solares distribuidos  

Energy Technology Data Exchange (ETDEWEB)

This work presents several different approaches to hierarchical control algorithms designed for a parabolic-trough solar collector field to demonstrate the possibility of maximizing hypothetical profit possible from this type of plant by improving and increasing plant automation. This study was developed in the current world power supply scenario, posing the possibility of using renewable energies (among which is solar thermal power), which the author is interested in contributing to advancing through research on improved plant operation control. The design was made for the ACUREX distributed solar collector field at the Plataforma Solar de Almeria. The control structures implemented to improve production in the solar collector field are based on a simple two-layered hierarchical control. One regulation layer (Layer 1) in which two proposals have been implemented: a control scheme developed using the feedback linearization technique and another proposal consisting on parallel deed forward control with an I-PD (Integral-Proportional Derivative) control. three proposals were implemented in the top layer (Layer 2) for generating the setpoint, the first one based on a physical model, the second one based on a fuzzy model, and the last uses the physical model and an optimization function for finding the optimum setpoint. (Author)

Martinez Cirre, C. R.

2008-07-01

120

Short-Term Solar Collector Power Forecasting  

OpenAIRE

This paper describes a new approach to online forecasting of power output from solar thermal collectors. The method is suited for online forecasting in many applications and in this paper it is applied to predict hourly values of power from a standard single glazed large area flat plate collector. The method is applied for horizons of up to 42 hours. Solar heating systems naturally come with a hot water tank, which can be utilized for energy storage also for other energy source...

Bacher, Peder; Madsen, Henrik; Perers, Bengt

2011-01-01

121

Estimate of the energy and environment impacts attributed to solar thermal collectors in Brazil; Estimativa dos impactos energeticos e ambientais atribuida aos coletores solares termicos nas residencias brasileiras  

Energy Technology Data Exchange (ETDEWEB)

The present study esteem the energy impacts, in terms of energy saving and reduction of peak demand, Real and Potential, as well as the environmental impacts, in terms of greenhouse gases (GHG) emission reduction, attributed to the use of solar thermal collectors in Brazil, in substitution to the electric showers. The evaluation of the energy saving, starting from the F Method, it was disaggregated in regional level, for the calculations of the solar fractions and distribution of the market and, starting from the energy saving and factor of national system emission, it was calculated the reductions of GHG effect. According to evaluations the use of solar thermal collectors in Brazil generated energy savings of the order of 1,073.2 GWh, what results in about 51,514 tCO{sub 2} of GHG emission reduction, equivalent to 104 thousand petroleum barrels, the year of 2008 and a reduction of peak demand of 1,220 MW, about 1.5% of the maximum demand registered on that year. It was verified, also, that Brazil uses less than 5% of the potential of solar thermal energy in the residential sector for water heating. (author)

Cardoso, Rafael Balbino [Universidade Federal de Itajuba (UNIFEI), Itabira, MG (Brazil)], E-mail: cardosorb@unifei.edu.br; Nogueira, Luiz Augusto Horta [Universidade Federal de Itajuba (UNIFEI), MG (Brazil)], E-mail: horta@unifei.edu.br

2011-04-15

122

ADVANCED HYBRID PARTICULATE COLLECTOR  

Energy Technology Data Exchange (ETDEWEB)

A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the US Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in a manner that has not been done before. The AHPC concept consists of a combination of fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two collection methods, both in the particulate collection step and in the transfer of dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emission with conventional ESPs, and it solves the problem of reentrainment and collection of dust in conventional baghouses. The AHPC is currently being tested at the 2.7-MW scale at the Big Stone power station.

Stanley Miller; Rich Gebert; William Swanson

1999-11-01

123

Application of radiant cooling as a passive cooling option in hot humid climate  

Energy Technology Data Exchange (ETDEWEB)

In hot and humid region, air-conditioning is increasingly used to attain thermal comfort. Air-conditioning is highly energy intensive and it is desirable to develop alternative low-energy means to achieve comfort. In a previous experimental investigation using a room equipped with radiant cooling panel, it was found that cooling water kept to 25{sup o}C could be used to attain thermal comfort under some situations, while water at such temperature would not cause condensation of moisture from air on the panel. This paper reports results of a series of whole-year simulations using TRNSYS computer code on applications of radiant cooling to a room model that represents the actual experimental room. Admitting the inability of radiant cooling to accept latent load, chilled water at 10{sup o}C was supplied to cooling coil to precool ventilation air while water cooled by cooling tower was used for radiant cooling in daytime application. For night-time, cooling water from cooling tower supplied for radiant cooling was found to be sufficient to achieve thermal comfort. Such applications are considered to be more amenable to residential houses. (author)

Vangtook, Prapapong; Chirarattananon, Surapong [Energy Field of Study, School of Environment, Resources and Development, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120 (Thailand)

2007-02-15

124

Optimal nonimaging integrated evacuated solar collector  

Science.gov (United States)

A non imaging integrated evacuated solar collector for solar thermal energy collection is discussed which has the lower portion of the tubular glass vacuum enveloped shaped and inside surface mirrored to optimally concentrate sunlight onto an absorber tube in the vacuum. This design uses vacuum to eliminate heat loss from the absorber surface by conduction and convection of air, soda lime glass for the vacuum envelope material to lower cost, optimal non imaging concentration integrated with the glass vacuum envelope to lower cost and improve solar energy collection, and a selective absorber for the absorbing surface which has high absorptance and low emittance to lower heat loss by radiation and improve energy collection efficiency. This leads to a very low heat loss collector with high optical collection efficiency, which can operate at temperatures up to the order of 250 degree(s)C with good efficiency while being lower in cost than current evacuated solar collectors. Cost estimates are presented which indicate a cost for this solar collector system which can be competitive with the cost of fossil fuel heat energy sources when the collector system is produced in sufficient volume. Non imaging concentration, which reduces cost while improving performance, and which allows efficient solar energy collection without tracking the sun, is a key element in this solar collector design.

Garrison, John D.; Duff, W. S.; O'Gallagher, Joseph J.; Winston, Roland

1993-11-01

125

Evaluación energética de un colector solar de placa plana de doble cubierta / Energy assessment of a double cover flat-plate solar collector  

Scientific Electronic Library Online (English)

Full Text Available En este artículo se establece la incidencia de la relación de aspecto (razón entre la longitud y ancho de un colector de área constante) sobre la eficiencia térmica de un colector solar de placa plana que utiliza doble cubierta transparente para el calentamiento de aire. Este estudio se realiza desd [...] e dos enfoques: el primero utiliza un modelo físico-matemático a partir de los balances de energía del colector, y el segundo utiliza un prototipo con su respectiva instrumentación para calcular su rendimiento de manera experimental. El colector está compuesto por una estructura en madera, una doble cubierta de vidrio transparente, una placa absorbedora de radiación solar y un ventilador para extraer el aire calentado. Para calcular el rendimiento se registraron de manera automática datos de temperatura, radiación solar y flujo másico de aire; durante aproximadamente 6 horas por varios días y bajo distintas condiciones climáticas de la ciudad de Montería, Córdoba (Colombia). En general se encontró, para un área constante del colector, que la eficiencia térmica de este aumenta cuando la relación de aspecto aumenta y que el modelo teórico se ajusta de manera aceptable con los resultados experimentales. Abstract in english This study establishes the effect of the aspect ratio (ratio between length and width of a constant collector area) on the thermal efficiency of a flat-plate solar collector that uses a double cover for air heating. The analysis has two approaches: first, using a physical-mathematical model that dev [...] elop a steady state analysis from a collector energy balance and the second, using an instrumented prototype to calculate its performance in experimental way. The collector configuration consists in a wood structure, a double glass cover, an absorber plate of solar radiation and blower to extract the heated air. To calculate the performance temperature data, solar radiation and mass flow of air were automatically recorded for about 6 hours for several days and under different weather conditions in the city of Montería, Cordoba. In general it was found, for a constant collector area, where the thermal efficiency increases when the aspect ratio increases and that the theoretical model fits in an acceptable way with the experimental results.

Adrián Enrique, Ávila Gómez; Jorge Mario, Mendoza Fandiño; Julio Fernando, Beltrán Sarmiento.

2010-06-01

126

New tool for standardized collector performance calculations  

DEFF Research Database (Denmark)

A new tool for standardized calculation of solar collector performance has been developed in cooperation between SP Technical Research Institute Sweden, DTU Denmark and SERC Dalarna University. The tool is designed to calculate the annual performance for a number of representative cities in Europe on the basis of parameters from collector tests performed according to EN12975, without any intermediate conversions. The main target group for this tool is test institutes and certification bodies that intend to use it for conversion of collector model parameters derived from performance tests, into a more user friendly quantity: the annual energy output. The energy output calculated by the tool can be expressed either per square meter or per collector module.

Perers, Bengt; Kovacs, Peter

2011-01-01

127

Intermittent tracking of flat plate collectors  

International Nuclear Information System (INIS)

A theoretical analysis of different intervals of intermittent two-axis tracking of the sun, on the amount of annual energy received by flat-plate collectors, has been carried out. The analysis was done for Ipoh, a city near the university at a latitude of 40 34 North in Malaysia. For the analysis, a computer program was developed to calculate the solar insulation according to the interval settings, considering ASHRAE Standard Sky assumption. Both direct and diffused components of solar radiation have been considered. The tracking system was targeted for flat plate collectors where the degree of tracking accuracy would be much lower Hence, the tracking mechanism will be much simpler and lower in costs. Results showed that by a 3-hour intermittent tracking, a flat-plate collector could get as much as 35% more annual energy than a fixed one. The 3-hour interval tracking greatly simplifies the gear mechanism from the motor to the solar collector. (Author)

128

An investigation on the performance characteristics of solar flat plate collector with different selective surface coatings  

OpenAIRE

In the present work, investigations are made to study performance characteristics of solar flat plate collector with different selective surface coatings. Flat plate collector is one of the important solar energy trapping device which uses air or water as working fluid. Of the many solar collector concepts presently being developed, the relative simple flat plate solar collector has found the widest application so far. Its characteristics are known, and compared with other collector types, it...

Madhukeshwara N, E. S. Prakash

2012-01-01

129

Thermal Performance Evaluation of Attic Radiant Barrier Systems Using the Large Scale Climate Simulator (LSCS)  

Energy Technology Data Exchange (ETDEWEB)

Application of radiant barriers and low-emittance surface coatings in residential building attics can significantly reduce conditioning loads from heat flow through attic floors. The roofing industry has been developing and using various radiant barrier systems and low-emittance surface coatings to increase energy efficiency in buildings; however, minimal data are available that quantifies the effectiveness of these technologies. This study evaluates performance of various attic radiant barrier systems under simulated summer daytime conditions and nighttime or low solar gain daytime winter conditions using the large scale climate simulator (LSCS). The four attic configurations that were evaluated are 1) no radiant barrier (control), 2) perforated low-e foil laminated oriented strand board (OSB) deck, 3) low-e foil stapled on rafters, and 4) liquid applied low-emittance coating on roof deck and rafters. All test attics used nominal RUS 13 h-ft2- F/Btu (RSI 2.29 m2-K/W) fiberglass batt insulation on attic floor. Results indicate that the three systems with radiant barriers had heat flows through the attic floor during summer daytime condition that were 33%, 50%, and 19% lower than the control, respectively.

Shrestha, Som S [ORNL; Miller, William A [ORNL; Desjarlais, Andre Omer [ORNL

2013-01-01

130

“ANALYSIS ON PERFORMANCE OF RADIANT HEAT EXCHANGER OF THERMIC FLUID HEATER BY CHANGING THE SUITABLE GRADE OF MATERIAL”  

Directory of Open Access Journals (Sweden)

Full Text Available To make the radiant heat exchanger of higher performance and efficiency at low manufacturing and maintenance cost in which maximum utilization of heat energy of flue gases is possible and also which is less expensive and easily accommodate by any process industries for their usual operation. Also to improve working condition and decrease the operating cost by changing the grade of material of tubes for required mechanical and thermal property for which the radiant heat exchanger is to be designed.

Patel Ronak I.

2014-09-01

131

Performances and yield assessment of glazed photovoltaic-thermal collectors  

OpenAIRE

Photovoltaic-Thermal (PV-T) hybrid collectors are multi-energy components that convert solar energy into both electricity and heat. In this paper, the performances of a PV-T collector are investigated. The objective is not only the evaluation of the PV-T collector itself, but the evaluation of this component operating in a real energy system. For this purpose, experimental prototypes of PV-T collector were built, tested in an indoor sun simulator and finally installed and monitored at the EDF...

Dupeyrat, P.; Fortuin, S.; Kwiatkowski, G.; Baranzini, M.; Schumann, M.

2012-01-01

132

Subjective evaluation of different ventilation concepts combined with radiant heating and cooling  

DEFF Research Database (Denmark)

Sixteen subjects evaluated the indoor environment in four experiments with different combinations of ventilation and radiant heating/cooling systems. Two test setups simulated a room in a low energy building with a single occupant during winter. The room was equipped either by a ventilation system supplying warm air space heating or by a combination of radiant floor heating and mixing ventilation system. Next two test setups simulated an office room with two occupants during summer, ventilated and cooled by a single displacement ventilation system or by a radiant floor cooling combined with displacement ventilation. Vertical air temperature distribution was more uniform for floor heating than for warm air heating, but there was no significant difference in thermal perception between the two mixing ventilation systems. For the summer conditions the subjects voted warmer than predicted by the PMV and about one third preferred more air movement. No significant difference in thermal perception between the two displacement ventilation systems was found.

Krajcik, Michal; Tomasi, Roberta

2012-01-01

133

Toward an Earth Clouds, Aerosols and Radiation Explore (EarthCARE) thermal flux determination: Evaluation using Clouds and the Earth's Radiant Energy System (CERES) true along-track data  

Science.gov (United States)

The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission developed by the European Space Agency and the Japan Aerospace Exploration Agency addresses the need to improve the understanding of the interactions between cloud, aerosol, and radiation processes. The broadband radiometer (BBR) instrument on board the EarthCARE spacecraft provides measurements of broadband reflected solar and emitted thermal radiances at the top of atmosphere (TOA) over the along-track satellite path at three fixed viewing zenith angles. The multiangular information provided by the BBR, combined with the spectral information from the EarthCARE's multispectral imager (MSI) can be exploited to construct accurate thermal radiance-to-flux conversion algorithms on the basis of radiative transfer modeling. In this study, the methodology to derive longwave (LW) fluxes from BBR and MSI data is described, and the performance of the LW BBR angular models is compared with the Clouds and the Earth's Radiant Energy System (CERES) Terra flux retrievals in order to evaluate the reliability of the BBR synthetic models when applied to satellite-based radiances. For this purpose, the BBR methodology proposed in this work is adapted to the CERES and the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument specifications, and new LW angular models for CERES are developed. According to plane-parallel simulations, the BBR LW flux uncertainty caused by flux inversion could be reduced up to 0.4 W m-2. The intercomparison between CERES BBR-like adapted and CERES original angular models is performed over a BBR-like database of CERES true along track, and the averaged instantaneous retrievals agree to within 2 W m-2.

Domenech, C.; Wehr, T.; Fischer, J.

2011-03-01

134

Modified solar collector flow factor  

Energy Technology Data Exchange (ETDEWEB)

The mean fluid temperature in a solar collector is often approximated by the average of the inlet and outlet temperatures. When this is done a simpler expression for the collector flow factor can be derived, the use of which permits the formal proof that collector efficiency will decrease with any maldistribution of fluid flow in the risers of the collector.

Okeefe, M.J.; Francey, J.L.A.

1985-01-01

135

SOLAR NANTENNA ELECTROMAGNETIC COLLECTORS  

Energy Technology Data Exchange (ETDEWEB)

This research explores a new efficient approach for producing electricity from the abundant energy of the sun. A nanoantenna electromagnetic collector (NEC) has been designed, prototyped, and tested. Proof of concept has been validated. The device targets mid-infrared wavelengths where conventional photovoltaic (PV) solar cells do not respond but is abundant in solar energy. The initial concept of designing NEC antennas was based on scaling of radio frequency antenna theory. This approach has proven unsuccessful by many due to not fully understanding and accounting for the optical behavior of materials in the THz region. Also until recent years the nanofabrication methods were not available to fabricate the optical antenna elements. We have addressed and overcome both technology barriers. Several factors were critical in successful implementation of NEC including: 1) frequency-dependent modeling of antenna elements, 2) selection of materials with proper THz properties and 3) novel manufacturing methods that enable economical large-scale manufacturing. The work represents an important step toward the ultimate realization of a low-cost device that will collect as well as convert this radiation into electricity, which will lead to a wide spectrum, high conversion efficiency, and low cost solution to complement conventional PVs.

Steven D. Novack; Dale K. Kotter; Dennis Slafer; Patrick Pinhero

2008-08-01

136

City sewer collectors biocorrosion  

Science.gov (United States)

This paper presents the biocorrosion of city sewer collectors impregnated with special polymer sulphur binders, polymerized sulphur, which is applied as the industrial waste material. The city sewer collectors are settled with a colony of soil bacteria which have corrosive effects on its structure. Chemoautotrophic nitrifying bacteria utilize the residues of halites (carbamide) which migrate in the city sewer collectors, due to the damaged dampproofing of the roadway and produce nitrogen salts. Chemoorganotrophic bacteria utilize the traces of organic substrates and produce a number of organic acids (formic, acetic, propionic, citric, oxalic and other). The activity of microorganisms so enables the origination of primary and secondary salts which affect physical properties of concretes in city sewer collectors unfavourably.

Ksia¸?ek, Mariusz

2014-12-01

137

Electrostatic radioactive particle collector  

International Nuclear Information System (INIS)

The facility includes an electrostatic field source whose outlets are connected to a collector electrode and a repulsive electrode and which is accommodated in an insulating casing in a manner such that the electrodes remain uncovered, partly at least. The electrostatic field source can be a capacitor or a formed electret; alternatively, voltage can be brought from an external source. The detector itself can serve as the collector electrode. The electrostatic collector is placed where the volume concentration of radioactive particles is to be measured. The radioactivity collected can be measured over a chosen period of collection by transferring the collector electrode to the detector, or continuously by collecting the radioactive particles directly onto the detector window or onto a thin electrode covering the window. (M.D.). 2 figs

138

Measurement of radiant properties of ceramic foam  

International Nuclear Information System (INIS)

An experimental facility is described for the measurement of the normal spectral and total emissivity and transmissivity of semi-transparent materials in the temperature range of 600 C to 1200 C. The set-up was used for the measurement of radiation properties of highly porous ceramic foam which is used in low NOx radiant burners. Emissivity and transmissivity data were measured and are presented for coated and uncoated ceramic foam of different thicknesses. (orig.)

139

Absolute radiant power measurement of the X-ray free-electron laser at SACLA  

International Nuclear Information System (INIS)

The Japanese hard X-ray free-electron laser (XFEL), SACLA (SPring-8 Angstrom Compact free-electron LAser), reached laser amplification at 10 keV photon energy in June 2011. SACLA can provide XFELs with its wavelength of shorter than 0.1 nm. Since the radiant power is a fundamental parameter of the XFEL beam which strongly influences nonlinear effects, its measurement in absolute terms is of significant importance. In the present study, the absolute radiant power of the XFEL was measured using a cryogenic radiometer at the BL3 in SACLA. The radiant power as a function of a silicon attenuator thickness was also measured to estimate the contribution of the higher harmonics. The radiant power in the range between 8 ?W and 1005 ?W was measured in the photon energies of 4.4 keV, 5.8 keV, 9.6 keV, 13.6 keV and 16.8 keV. The contribution of the higher harmonics is negligible except for the photon energy of 4.4 keV. The third harmonics component in the photon energy of 4.4 keV is about 1 %.

140

Theoretical Analysis of Solar Thermal Collector with a Flat Plate Bottom Booster Reflector  

Directory of Open Access Journals (Sweden)

Full Text Available

A theoretical analysis of a solar thermal collector with a flat plate bottom reflector is presented. The bottom reflector extends from the lower edge of the collector. The variations of daily solar radiation absorbed on the collector with inclinations from horizontal for both the collector and reflector throughout the year were predicted, and the optimum inclinations of the collector and reflector which maximize the daily solar radiation absorbed on the collector were determined for each month at 30oN latitude. The effects of the size of the collector and reflector on the daily solar radiation absorbed on the collector were also investigated. The optimum collector inclination is lower in summer and higher in winter, while the optimum reflector inclination is higher in summer and lower in winter. The average daily solar radiation absorbed on the collector throughout the year can be increased about 20%, 27% and 33% by using a bottom reflector if the ratio of reflector length to collector length is 0.5, 1.0 and 2.0, respectively, when the collector’s length is equal to its width.

 Key words: Solar energy; Solar thermal collector; Bottom reflector; Collector-reflector; Optimum inclination

Hiroshi Tanaka

2011-12-01

141

Asphalt solar collectors: A literature review  

International Nuclear Information System (INIS)

Highlights: ? Solar energy can be harnessed by asphalt pavements. ? Research on asphalt thermal behavior and asphalt solar collectors is reviewed. ? Asphalt temperature is very sensitive to the variation of absortivity. ? Asphalt solar collector efficiency depends on flow rate and geometrical parameters. -- Abstract: Asphalt pavements subject to solar radiation can reach high temperatures causing not only environmental problems such as the heat island effect on cities but also structural damage due to rutting or hardening as a result of thermal cycles. Asphalt solar collectors are doubly effective active systems: as they solve the previously mentioned problems and, moreover, they can harness energy to be used in different applications. The main findings of the existing research on asphalt solar collectors are gathered together in this review paper. Firstly, the main heat transfer mechanisms involved in the solar energy collection process are identified and the most important parameters and variables are presented. After analyzing the theoretical foundations of the heat transfer process, this review focuses on the types of studies carried out so far on asphalt’s thermal behavior, different methodologies employed by other authors to study asphalt solar collectors and influence of the variables involved in thermal energy harvesting.

142

ADVANCED HYBRID PARTICULATE COLLECTOR  

Energy Technology Data Exchange (ETDEWEB)

A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the US Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in an entirely novel manner. The AHPC concept combines fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two methods, both in the particulate collection step and in transfer of dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emissions with conventional ESPs, and solves the problem of reentrainment and recollection of dust in conventional baghouses. Phase I of the development effort consisted of design, construction, and testing of a 5.7-m{sup 3}/min (200-acfm) working AHPC model. Results from both 8-hour parametric tests and 100-hour proof-of-concept tests with two different coals demonstrated excellent operability and greater than 99.99% fine-particle collection efficiency.

Stanley J. Miller; Grant L. Schelkoph; Grant E. Dunham

2000-12-01

143

High-performance vacuum tubes for more energy efficiency. Building-integrated CPC vacuum tube collectors unite several functions.; Hochleistungs-Vakuumroehren fuer mehr Energieeffizienz. Gebaeudeintegrierte CPC-Vakuumroehren-Kollektoren vereinen mehrere Funktionen  

Energy Technology Data Exchange (ETDEWEB)

The performance of solar collectors primarily contributes to increased efficiency and reduced operating costs of solar thermal systems. With the use of building-integrated CPC vacuum tube collectors an extremely high energy yield is achieved on a smaller collector gross area. As a building-integrated system solution the CPC facade provide panels in addition to its use as spandrel panels within the glazed buildings not only an architectural design element, but unite as a multifunctional component for several functions. [German] Die Leistungsfaehigkeit der Solarkollektoren traegt primaer zur Effizienzsteigerung und Reduzierung der Betriebskosten einer Solarthermieanlagen bei. Mit dem Einsatz gebaeudeintegrierter CPC-Vakuumroehrenkollektoren wird auf einer kleineren Kollektorbruttoflaeche ein extrem hoher Energieertrag erreicht. Als gebaeudeintegrierte Systemloesung bieten die CPC-Fassadenkollektoren neben dem Einsatz als Bruestungselemente auch innerhalb der verglasten Gebaeuden nicht nur ein architektonisches Gestaltungselement, sondern vereinen als multifunktionaler Bestandteil noch mehrere Funktionen.

Theiss, Eric

2013-10-15

144

A Concentrated Solar Power Unit Collector’s Efficiency under varied wind speeds  

OpenAIRE

Concentrated Solar Power (CSP) harnesses the sun?s solar energy to produce electricity. This report provides a technical analysis of the potential for CSP to provide low cost renewable electricity in Bhopal (M.P.) and outlines the impact of varied wind speeds on its collector?s efficiency. Yields of CSP Plants depend strongly on site-specific meteorological conditions. Meteorological parameters that can influence the performance of CSP plant are Direct Norm...

Ajay Vardhan,; Tiwar, A. C.; Arvind Kausha; Sunil Hotchandani,

2013-01-01

145

Solar Heating Systems with Evacuated Tubular Solar Collector  

DEFF Research Database (Denmark)

Recently different designed evacuated tubular solar collectors were introduced on the market by different Chinese companies. In the present study, investigations on the performance of four different Chinese evacuated tubular collectors and of solar heating systems using these collectors were carried out, employing both laboratory test and theoretical calculations. The collectors were tested in a small solar domestic hot water (SDHW) system in a laboratory test facility under realistic conditions. The yearly thermal performance of solar heating systems with these evacuated tubular collectors, as well as with normal flat-plate collectors was calculated under Danish weather conditions. It is found that, for small SDHW systems with a combi tank design, an increase of 25% -55% net utilized solar energy can be achieved by using these evacuated tubular collectorsinstead of normal flat-plate collectors. For solar heating plants, the yearly energy output from these evacuated tubular collectors is about 40%-90% higher than the output from typical flat-plate collectors at an operation temperature of about 50°C.

Qin, Lin; Furbo, Simon

1998-01-01

146

A tool for standardized collector performance calculations including PVT  

DEFF Research Database (Denmark)

A tool for standardized calculation of solar collector performance has been developed in cooperation between SP Technical Research Institute of Sweden, DTU Denmark and SERC Dalarna University. The tool is designed to calculate the annual performance of solar collectors at representative locations in Europe. The collector parameters used as input in the tool are compiled from tests according to EN12975, without any intermediate conversions. The main target group for this tool is test institutes and certification bodies that are intended to use it for conversion of collector model parameters (derived from performance tests) into a more user friendly quantity: the annual energy output. The energy output presented in the tool is expressed as kWh per collector module. A simplified treatment of performance for PVT collectors is added based on the assumption that the thermal part of the PVT collector can be tested and modeled as a thermal collector, when the PV electric part is active with an MPP tracker in operation. The thermal collector parameters from this operation mode are used for the PVT calculations.

Perers, Bengt; Kovacs, Peter

2012-01-01

147

Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth's Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part II; Validation  

Science.gov (United States)

Top-of-atmosphere (TOA) radiative fluxes from the Clouds and the Earth s Radiant Energy System (CERES) are estimated from empirical angular distribution models (ADMs) that convert instantaneous radiance measurements to TOA fluxes. This paper evaluates the accuracy of CERES TOA fluxes obtained from a new set of ADMs developed for the CERES instrument onboard the Tropical Rainfall Measuring Mission (TRMM). The uncertainty in regional monthly mean reflected shortwave (SW) and emitted longwave (LW) TOA fluxes is less than 0.5 W/sq m, based on comparisons with TOA fluxes evaluated by direct integration of the measured radiances. When stratified by viewing geometry, TOA fluxes from different angles are consistent to within 2% in the SW and 0.7% (or 2 W/sq m) in the LW. In contrast, TOA fluxes based on ADMs from the Earth Radiation Budget Experiment (ERBE) applied to the same CERES radiance measurements show a 10% relative increase with viewing zenith angle in the SW and a 3.5% (9 W/sq m) decrease with viewing zenith angle in the LW. Based on multiangle CERES radiance measurements, 18 regional instantaneous TOA flux errors from the new CERES ADMs are estimated to be 10 W/sq m in the SW and, 3.5 W/sq m in the LW. The errors show little or no dependence on cloud phase, cloud optical depth, and cloud infrared emissivity. An analysis of cloud radiative forcing (CRF) sensitivity to differences between ERBE and CERES TRMM ADMs, scene identification, and directional models of albedo as a function of solar zenith angle shows that ADM and clear-sky scene identification differences can lead to an 8 W/sq m root-mean-square (rms) difference in 18 daily mean SW CRF and a 4 W/sq m rms difference in LW CRF. In contrast, monthly mean SW and LW CRF differences reach 3 W/sq m. CRF is found to be relatively insensitive to differences between the ERBE and CERES TRMM directional models.

Loeb, N. G.; Loukachine, K.; Wielicki, B. A.; Young, D. F.

2003-01-01

148

TELBE - the super-radiant THz facility at ELBE  

Energy Technology Data Exchange (ETDEWEB)

It has been shown recently that relativistic electron bunches can be utilized for the generation of super-radiant coherent THz radiation by one single pass through an undulator, bending magnet, or CDR/CTR screens. However, the high THz fields have all been achieved at large accelerators that allow for high electron beam energies. A crucially important research topic for the next years at the HZDR is therefore to investigate whether an equally fine control over highly charged electron bunch form can be routinely achieved in a low electron beam energy accelerator like ELBE. If successful this development would allow the generation of high field THz fields by linear accelerators at considerably reduced cost. Given stable operation can be provided, TELBE, could also become a world-wide unique research facility for high field THz science. The current status and an outlook on future developments are presented.

Green, Bertram; Kovalev, Sergei; Hauser, Jens; Kuntzsch, Michael; Schneider, Harald; Winnerl, Stephan; Seidel, Wolfgang; Zvyagin, Sergei; Lehnert, Ulf; Helm, Manfred; Michel, Peter; Gensch, Michael [Helmholtz-Zentrum Dresden-Rossendorf (Germany); Al-Shemmary, Alaa; Radu, Ilie; Stojanovic, Nikola; Cavalleri, Andrea [Deutsches Elektronen-Synchrotron (Germany); Wall, Simon [FHI Berlin (Germany); Eng, Lukas M. [Technische Universitaet Dresden (Germany); Heberle, Joachim [FU Berlin (Germany)

2013-07-01

149

TELBE - the super-radiant THz facility at ELBE  

International Nuclear Information System (INIS)

It has been shown recently that relativistic electron bunches can be utilized for the generation of super-radiant coherent THz radiation by one single pass through an undulator, bending magnet, or CDR/CTR screens. However, the high THz fields have all been achieved at large accelerators that allow for high electron beam energies. A crucially important research topic for the next years at the HZDR is therefore to investigate whether an equally fine control over highly charged electron bunch form can be routinely achieved in a low electron beam energy accelerator like ELBE. If successful this development would allow the generation of high field THz fields by linear accelerators at considerably reduced cost. Given stable operation can be provided, TELBE, could also become a world-wide unique research facility for high field THz science. The current status and an outlook on future developments are presented.

150

Tracking system for solar collectors  

Science.gov (United States)

A tracking system is provided for pivotally mounted spaced-apart solar collectors. A pair of cables is connected to spaced-apart portions of each collector, and a driver displaces the cables, thereby causing the collectors to pivot about their mounting, so as to assume the desired orientation. The collectors may be of the cylindrical type as well as the flat-plate type. Rigid spar-like linkages may be substituted for the cables. Releasable attachments of the cables to the collectors is also described, as is a fine tuning mechanism for precisely aligning each individual collector.

Butler, Barry L. (Golden, CO)

1984-01-01

151

COMPARISON OF PROPORTIONAL AND ON/OFF SOLAR COLLECTOR LOOP CONTROL STRATEGIES USING A DYNAMIC COLLECTOR MODEL  

Energy Technology Data Exchange (ETDEWEB)

Common control strategies used to regulate the flow of liquid through flat-plate solar collectors are discussed and evaluated using a dynamic collector model. Performance of all strategies is compared using different set points, flow rates, insolation levels and patterns (clear and cloudy days), and ambient temperature conditions. The unique characteristic of the dynamic collector model is that it includes effects of collector capacitance. In general, capacitance has a minimal effect on long term collector performance; however, short term temperature response and the energy =storage capability of collector capacitance are shown to play significant roles in comparing on/off and proportional controllers. Inclusion of these effects has produced considerably more realistic simulations than any generated by steady-state models. Simulations indicate relative advantages and disadvantages of both types of controllers, conditions under which each performs better, and the importance of pump cycling and controller set points on total energy collection. Results show that the turn-on set point is not always a critical factor in energy collection since collectors store energy while they warm up and during cycling; and, that proportional flow controllers provide improved energy collection only during periods of interrupted or very low insolation when the maximum possible energy collection is rela= tively low. Although proportional controllers initiate flow ·at lower insolation levels than on/off controllers, proportional controllers produce lower flow rates and higher average collector temperatures resulting in slightly lower instantaneous collection efficiencies.

Schiller, Steven R.; Warren, Mashuri L.; Auslander, David M.

1979-12-01

152

Effects of different collector’s area on the coupling of a thermosiphon collector and a single zone  

International Nuclear Information System (INIS)

Graphical abstract: - Highlights: • We simulate a thermosiphon collector associated to a single zone using TRNSYS. • We examine the temperature of water in collector, in tank and in single zone. • We study the temporal evolution of the temperature and the energy for 11 h operation in January and 2880 h operation in winter. • The system gives good results in all operating states. • The use of solar energy in the residential building is interesting. - Abstract: The novelty of this paper is the coupling between a thermosiphon collector and a single zone with the following details; a thermosiphon system (TYPE 45) which uses the solar energy as an unlimited renewable energy to produce the heat by using an internal coupling of a flat plate collector and a storage tank in a closed loop realized in TRNSYS. Consequently, the user simply utilizes TYPE 45 as thermosiphon ready to be run, and a single zone (TYPE 19) is a complex type which is designed for residential buildings that can be specified by the user in order to obtain an acceptable heating within a house. The user specified the characteristics of the internal space, external weather conditions, walls, windows, and doors. To facilitate this description, the parameters and inputs for this component are organized in separate table according to a logical structure. According to us, the choice of this model of thermosiphon coupled with a single zone can have multiple interesting engineering applications, in particular ameliorating the mode of the heating in residential buildings. Two flat plate collectors of aperture area of 6 and 8 m2 are modeled. The solar fraction of the entire system is used as the optimization parameter. The temperature of the water in the storage tank, the collector’s temperature, the temperature inside and outside the house, the solar fraction for different collector areas and the total energy were also measured in 11 h operation in January and 2880 h operation in winter. The average solar fraction obtained was 85% and the system could cover all the hot water needs of a house of six people. The maximum auxiliary energy was needed during 11 h operation in January and 4 months in winter. The results show that by utilizing solar energy, the designed system could provide 40–70% of the hot water demands in winter

153

Performance evaluation of radiant baseboards (skirtings) for room heating – An analytical and experimental approach  

International Nuclear Information System (INIS)

The aim of this study was to investigate the thermal performance of the hydronic radiant baseboards currently used for space heating in built environments. The presently available equations for determination of heat outputs from these room heaters are valid for a certain height at a specific temperature range. This limitation needed to be addressed as radiant baseboards may be both energy and cost efficient option for space heating in the future. The main goal of this study was therefore to design an equation valid for all baseboard heights (100–200 mm) and excess temperatures (9–60 °C) usually used in built environments. The proposed equation was created by curve fitting using the standard method of least squares together with data from previous laboratory measurements. It was shown that the predictions by the proposed equation were in close agreement with reported experimental data. Besides, it was also revealed that the mean heat transfer coefficient of the investigated radiant baseboards was about 50% higher than the mean heat transfer coefficient of five conventional panel radiators of different types. The proposed equation can easily be used or programed in energy simulation codes. Hopefully this will help engineers to quantify more accurately the energy consumption for space heating in buildings served by radiant baseboards. -- Highlights: • Thermal performance of radiant baseboards (RBs) used for space heating was analyzed. • The proposed heat output equation can be used with confidence for RBs heaters. • The heat transfer ability of RBs was 50% higher than that of panel radiators. • The heat emission from RBs increased by roughly 2.1% per centimeter of height. • The RBs of maximum height should be used for water supply temperatures below 45 °C

154

Vented Cavity Radiant Barrier Assembly And Method  

Science.gov (United States)

A vented cavity radiant barrier assembly (2) includes a barrier (12), typically a PV module, having inner and outer surfaces (18, 22). A support assembly (14) is secured to the barrier and extends inwardly from the inner surface of the barrier to a building surface (14) creating a vented cavity (24) between the building surface and the barrier inner surface. A low emissivity element (20) is mounted at or between the building surface and the barrier inner surface. At least part of the cavity exit (30) is higher than the cavity entrance (28) to promote cooling air flow through the cavity.

Dinwoodie, Thomas L. (Piedmont, CA); Jackaway, Adam D. (Berkeley, CA)

2000-05-16

155

Spatial distribution and temporal variability of solar radiant over southern Thailand  

Energy Technology Data Exchange (ETDEWEB)

The potential for solar energy in Thailand has been estimated at over 50,000 MW for power generation. However, existing power plants in the country produce only 32 MW. Most the the systems have been installed in rural areas, islands and other off-grid sites. The availability and variability of global solar radiant intensity and its spatial distribution are key parameters for designing and testing outdoor solar energy systems. These parameters must be well understood in order to evaluate system efficiency at specific locations. Therefore, this study examined the spatial distribution and temporal variability of solar radiant over southern Thailand using the Surfer computer program. The incident of solar radiation on a horizontal plane was estimated at 14 synoptic stations using the Angstrom's correlation which was obtained from meteorological data. Rainfall quantity at 3 main meteorological stations was used to correlate the hours of sunshine and to predict them in meteorological stations where sunshine recorders were absent but where rainfall data were present. The 3 stations were at the Surat Thani, Phuket and Hat Yai airports. Angstrom's correlation coefficients were obtained using the correlation between the hours of sunshine and day length. The solar radiant was obtained once the extraterrestrial solar radiation was known. The study showed that the solar radiant over southern Thailand varies between 12.51 to 24.54 MJ per m{sup 2} per day. It was concluded that the temporal variation of solar radiant over southern Thailand is highly influenced by the North-East and South-West monsoons. 16 refs., 1 tab., 17 figs.

Waewsak, J.; Chancham, C. [Thaksin Univ., Phatthalung (Thailand). Dept. of Physics, Renewable Energy System Research and Demonstration Center, Solar and Wind Energy Research Lab

2009-07-01

156

Optimum solar collector fluid flow rates  

DEFF Research Database (Denmark)

Experiments showed that by means of a standard electronically controlled pump, type UPE 2000 from Grundfos it is possible to control the flow rate in a solar collector loop in such a way that the flow rate is strongly influenced by the temperature of the solar collector fluid passing the pump. The flow rate is increasing for increasing temperature.The flow rate at the high temperature level is typically 70 % greater than the flow rate at the low temperature level.Further, the energy consumption for the electronically controlled pump in a solar heating system will be somewhat smaller than the energy consumption of a normal ciculation pump in the solar heating system.Calculations showed that the highest thermal performances for small SDHW systems based on mantle tanks with constant volume flow rates in the solar collector loops are achieved if the flow rate is situated in the interval from 0.2 to 0.3 l/min. per m^2 solar collector for combi tank systems and in the interval from 0.3 to 0.4 l/min. per m^2 solar collector for preheating systems. Further, calculations showed that by means of an advanced control strategy for the flow rate - for instance if the flow rate is directly proportional to the temperature difference between the solar collector and the bottom of the mantle - an increase of about 1% of the thermal performance is possible.Finally, calculations showed that the highest thermal performance for large SDHW systems with constant volume flow rates in the solar collector loops are achieved if the flow rates in the solar collector loops are between 0.15 and 0.2 l/min. per m^2 solar collector. Also for large systems an increase of about 1% is possible by means of an advanced control strategy for the flow rate.Most likely, better control strategies than the investigated control strategies can be found. However, it is unlikely that significant thermal increases can be achieved by means of advanced control strategies.

Furbo, Simon; Shah, Louise Jivan

1996-01-01

157

Phase-Change Thermal Energy Storage  

Science.gov (United States)

The goal of this program is to advance the engineering and scientific understanding of solar thermal technology and to establish the technology base from which private industry can develop solar thermal power production options for introduction into the competitive energy market. Solar thermal technology concentrates the solar flux using tracking mirrors or lenses onto a receiver where the solar energy is absorbed as heat and converted into electricity or incorporated into products as process heat. The two primary solar thermal technologies, central receivers and distributed receivers, employ various point and line-focus optics to concentrate sunlight. Current central receiver systems use fields of heliostats (two-axes tracking mirrors) to focus the sun's radiant energy onto a single, tower-mounted receiver. Point focus concentrators up to 17 meters in diameter track the sun in two axes and use parabolic dish mirrors or Fresnel lenses to focus radiant energy onto a receiver. Troughs and bowls are line-focus tracking reflectors that concentrate sunlight onto receiver tubes along their focal lines. Concentrating collector modules can be used alone or in a multimodule system. The concentrated radiant energy absorbed by the solar thermal receiver is transported to the conversion process by a circulating working fluid. Receiver temperatures range from 100 C in low-temperature troughs to over 1500 C in dish and central receiver systems.

1989-11-01

158

Yearly average performance of the principal solar collector types  

Energy Technology Data Exchange (ETDEWEB)

The results of hour-by-hour simulations for 26 meteorological stations are used to derive universal correlations for the yearly total energy that can be delivered by the principal solar collector types: flat plate, evacuated tubes, CPC, single- and dual-axis tracking collectors, and central receiver. The correlations are first- and second-order polynomials in yearly average insolation, latitude, and threshold (= heat loss/optical efficiency). With these correlations, the yearly collectible energy can be found by multiplying the coordinates of a single graph by the collector parameters, which reproduces the results of hour-by-hour simulations with an accuracy (rms error) of 2% for flat plates and 2% to 4% for concentrators. This method can be applied to collectors that operate year-around in such a way that no collected energy is discarded, including photovoltaic systems, solar-augmented industrial process heat systems, and solar thermal power systems. The method is also recommended for rating collectors of different type or manufacturer by yearly average performance, evaluating the effects of collector degradation, the benefits of collector cleaning, and the gains from collector improvements (due to enhanced optical efficiency or decreased heat loss per absorber surface). For most of these applications, the method is accurate enough to replace a system simulation.

Rabl, A.

1981-01-01

159

A RADIANT AIR-CONDITIONING SYSTEM USING SOLAR-DRIVEN  

Directory of Open Access Journals (Sweden)

Full Text Available Every air-conditioning system needs some fresh air to provide adequate ventilation air required to remove moisture, gases like ammonia and hydrogen sulphide, disease organisms, and heat from occupied spaces. However, natural ventilation is difficult to control because urban areas outside air is often polluted and cannot be supplied to inner spaces before being filtered. Besides the high electrical demand of refrigerant compression units used by most air-conditioning systems, and fans used to transport the cool air through the thermal distribution system draw a significant amount of electrical energy in comparison with electrical energy used by the building thermal conditioning systems. Part of this electricity heats the cooled air; thereby add to the internal thermal cooling peak load. In addition, refrigerant compression has both direct and indirect negative effects on the environment on both local and global scales. In seeking for innovative air-conditioning systems that maintain and improve indoor air quality under potentially more demanding performance criteria without increasing environmental impact, this paper presents radiant air-conditioning system which uses a solar-driven liquid desiccant evaporative cooler. The paper describes the proposed solar-driven liquid desiccant evaporative cooling system and the method used for investigating its performance in providing cold water for a radiant air-conditioning system in Khartoum (Central Sudan. The results of the investigation show that the system can operate in humid as well as dry climates and that employing such a system reduces air-conditioning peak electrical demands as compared to vapour compression systems.

S. A. ABDALLA

2006-12-01

160

Coupon Collector Experiment  

Science.gov (United States)

This resource consists of a Java applet and expository text. The applet is a simulation of the coupon collector problem, which consists of sampling from the first m positive integers, with replacement, until k distinct values are obtained. The parameters m and k can be varied. The random variable of interest is the size of the sample.

Kyle Siegrist

161

Yearly average performance of the principal solar collector types  

Energy Technology Data Exchange (ETDEWEB)

The results of hour-by-hour computer calculations for 26 U.S. meteorological stations are used to derive universal correlations for the yearly total energy that can be delivered by various solar collector types: flat plates, evacuated tubes, CPC, collectors that track about one axis, collectors that track about two axes, and central receivers. The correlations, polynomials of first and second order in yearly average insolation, latitude, and threshold, are used to find the yearly collectible energy by reading a single graph and multiplying the coordinates by the collector parameters. The method is shown to reproduce the results of the computer calculations with an accuracy of 2% for flat plates and 2-4% for concentrators. The method can be applied to photovoltaic systems, solar-augmented industrial process heat systems, or solar thermal power systems it can also be used to rate collectors on the basis of yearly average performance or to evaluate the effects of collector degradation, the benefits of collector cleaning, and the gains from collector improvements.

Rabl, A.

1981-01-01

162

Optical, Energetic and Exergetic Analyses of Parabolic Trough Collectors  

Science.gov (United States)

Parabolic trough collectors generate thermal energy from solar energy. Especially, they are very convenient for applications in high temperature solar power systems. To determine the design parameters, parabolic trough collectors must be analysed with optical analysis. In addition, thermodynamics (energy and exergy) analysis in the development of an energy efficient system must be achieved. Solar radiation passes through Earth's atmosphere until it reaches on Earth's surface and is focused from the parabolic trough collector to the tube receiver with a transparent insulated envelope. All of them constitute a complex mechanism. We investigate the geometry of parabolic trough reflector and characteristics of solar radiation to the reflecting surface through Earth's atmosphere, and calculate the collecting total energy in the receiver. The parabolic trough collector, of which design parameters are given, is analysed in regard to the energy and exergy analysis considering the meteorological specification in May, June, July and August in Isparta/Turkey, and the results are presented.

Murat, Öztürk; Nalan Çiçek, Bezir; Nuri, Özek

2007-07-01

163

Fog collectors and collection techniques  

Science.gov (United States)

The earth sciences taught that due to the occurrence of water in three phases: gas, liquid and solid, solar energy keeps the hydrological cycle going, shaping the earth surface while regulating the climate and thus allowing smart technologies to interfere in the natural process by rerouting water and employing its yield for natural and human environments’ subsistence. This is the case of traditional fog collectors implemented by several researchers along the Atacama Desert since late ’50s such as vertical tensile mesh or macro-diamonds structures. Nevertheless, these basic prototypes require to be upgraded, mainly through new shapes, fabrics and frameworks’ types by following the principles of lightness, transformability, portability and polyvalence. The vertical canvas of conventional fog collectors contain too much stressed at each joints and as result it became vulnerable. Our study constitutes a research by design of two fog-trap devices along the Atacama Desert. Different climatic factors influence the efficiency of fog harvesting. In order to increase yield of collected fog water, we need to establish suitable placements that contain high rates of fog’s accumulation. As important as the location is also the building reliability of these collectors that will be installed. Their frames and skins have to be adjustable to the wind direction and resistant against strong winds and rust. Its fabric need to be more hydrophobic, elastic and with light colours to ease dripping/drainage and avoid ultra-violet deterioration. In addition, meshes should be well-tensed and frames well-embraced too. In doing so we have conceived two fog collectors: DropNet© (Höhler) and FogHive© (Suau). These designs explore climatic design parameters combined with the agile structural principles of Tensegrity and Geodesic widely developed by Bucky Fuller and Frei Otto. The research methods mainly consisted of literature review; fieldwork; comparative analysis of existing fog collection’s techniques and climatic design simulations. DropNet© is a lightweight fog collector kit -a standing-alone web- resistant against very strong winds. It is constructed with an elastic mesh according to the required tension. Apart from this, it is ease to be transported, assemble and relocated due to its tent-like construction. As a flexible construction it can be installed on flatten or uneven grounds. FogHive© is a modular space-frame, fully wrapped with a light waxy mesh, that can collect water fog and also performs like a shading/cooling device and a soil humidifier for greenery and potential inhabitation. Its body consists of a deployable polygonal structure with an adjustable polyvalent membrane which performs as water repellent skin (facing prevailing winds) and shading device facing Equator. In addition, a domestic wind turbine is installed within the structural frame to provide autonomous electrification. Both models have great applicability to provide drinking water in remote place and also irrigating water to repair or re-establish flora. Water collector, filtering (purification) and irrigation network are designed with appropriate materials and techniques.

Höhler, I.; Suau, C.

2010-07-01

164

Optimal design of orientation of PV/T collector with reflectors  

International Nuclear Information System (INIS)

Hybrid conversion of solar radiation implies simultaneous solar radiation conversion into thermal and electrical energy in the PV/Thermal collector. In order to get more thermal and electrical energy, flat solar radiation reflectors have been mounted on PV/T collector. To obtain higher solar radiation intensity on PV/T collector, position of reflectors has been changed and optimal position of reflectors has been determined by both experimental measurements and numerical calculation so as to obtain maximal concentration of solar radiation intensity. The calculated values have been found to be in good agreement with the measured ones, both yielding the optimal position of the flat reflector to be the lowest (5o) in December and the highest (38o) in June. In this paper, the thermal and electrical efficiency of PV/T collector without reflectors and with reflectors in optimal position have been calculated. Using these results, the total efficiency and energy-saving efficiency of PV/T collector have been determined. Energy-saving efficiency for PV/T collector without reflectors is 60.1%, which is above the conventional solar thermal collector, whereas the energy-saving efficiency for PV/T collector with reflectors in optimal position is 46.7%, which is almost equal to the values for conventional solar thermal collector. Though the energy-saving efficiency of PV/T collector decreases slightly with the solar radiation intensity concentration factor, i.e.ation intensity concentration factor, i.e. the thermal and electrical efficiency of PV/T collector with reflectors are lower than those of PV/T collector without reflectors, the total thermal and electrical energy generated by PV/T collector with reflectors in optimal position are significantly higher than total thermal and electrical energy generated by PV/T collector without reflectors.

165

Performance of a two-phase unglazed solar evaporator-collector  

Energy Technology Data Exchange (ETDEWEB)

In this study, the performance of a two-phase unglazed solar evaporator-collector in a heat pump solar cooling, water heating and drying system is investigated. This type of collector can be locally made and relatively much cheaper than the conventional collector. Refrigerant R-134a is used as the working fluid due to the better thermodynamic and environmental performance. A transient two-dimensional mathematical model of the evaporator-collector has been developed to predict temperature distribution and useful energy gain. A series of experiments were performed under the meteorological conditions of Singapore. Both experimental and analytical results show the fact that the two-phase unglazed solar evaporator-collector, instead of losing energy to the ambient, gained a significant amount due to low operating temperature of the collector. As a result, the collector efficiency attains a value greater than 1, when conventional collector equation is used. With this evaporator-collector, the system can be operated even in the absence of solar radiation. Experiments with a header type parallel tube evaporator-collector and serpentine collector indicate a better performance of serpentine one. This analysis shows that the two-phase unglazed solar evaporator-collector has good potential for application in the tropics. (orig.)

Hawlader, M.N.A.; Ye, Shaochun [Dept. of Mechanical Engineering, National Univ. of Singapore (Singapore)

2008-07-01

166

Optimal tilt-angles of all-glass evacuated tube solar collectors  

International Nuclear Information System (INIS)

In this paper, a detailed mathematical procedure is developed to estimate daily collectible radiation on single tube of all-glass evacuated tube solar collectors based on solar geometry, knowledge of two-dimensional radiation transfer. Results shows that the annual collectible radiation on a tube is affected by many factors such as collector type, central distance between tubes, size of solar tubes, tilt and azimuth angles, use of diffuse flat reflector (DFR, in short); For collectors with identical parameters, T-type collectors (collectors with solar tubes tilt-arranged) annually collect slightly more radiation than H-type collectors (those with solar tubes horizontally arranged) do. The use of DFR can significantly improve the energy collection of collectors. Unlike the flat-plate collectors, all-glass evacuated tube solar collectors should be generally mounted with a tilt-angle less than the site latitude in order to maximize the annual energy collection. For most areas with the site latitude larger than 30o in China, T-type collectors should be installed with a tilt-angle about 10o less than the site latitude, whereas for H-type collectors without DFR, the reasonable tilt-angle should be about 20o less than the site latitude. Effects of some parameters on the annual collectible radiation on the collectors are also presented.

167

The radiant of the Leonids meteor storm in 2001  

CERN Document Server

We have measured the radiant of the Leonids meteor storm in November 2001 by using new observational and analysis techniques. The radiant was measured as the intersections of lines which were detected and extrapolated from images obtained at a single observing site (Akeno Observatory, Japan). The images were obtained by two sets of telephoto lenses equipped with cooled CCD cameras. The measured radiant, (R.A., Dec.)=(154$^\\circ$.35, 21$^\\circ$.55) (J2000), is found to be in reasonable agreement with the theoretical prediction by McNaught and Asher (2001), which verifies their dust trail theory.

Torii, K; Yanagisawa, T; Ohnishi, K; Torii, Ken'ichi; Kohama, Mitsuhiro; Yanagisawa, Toshifumi; Ohnishi, Kouji

2002-01-01

168

The weighted words collector  

CERN Document Server

Motivated by applications in bioinformatics, we consider the word collector problem, i.e. the expected number of calls to a random weighted generator of words of length $n$ before the full collection is obtained. The originality of this instance of the non-uniform coupon collector lies in the, potentially large, multiplicity of the words/coupons of a given probability/composition. We obtain a general theorem that gives an asymptotic equivalent for the expected waiting time of a general version of the Coupon Collector. This theorem is especially well-suited for classes of coupons featuring high multiplicities. Its application to a given language essentially necessitates some knowledge on the number of words of a given composition/probability. We illustrate the application of our theorem, in a step-by-step fashion, on three exemplary languages, revealing asymptotic regimes in $\\Theta(\\mu(n)\\cdot n)$ and $\\Theta(\\mu(n)\\cdot \\log n)$, where $\\mu(n)$ is the sum of weights over words of length $n$.

Boisberranger, Jérémie Du; Ponty, Yann

2012-01-01

169

Electron beam collector for a microwave power tube  

Science.gov (United States)

This invention relates to a cylindrical, electron beam collector that efficiently couples the microwave energy out of a high power microwave source while stopping the attendant electron beam. The interior end walls of the collector are a pair of facing parabolic mirrors and the microwave energy from an input horn is radiated between the two mirrors and reassembled at the entrance to the output waveguide where the transmitted mode is reconstructed. The mode transmission through the collector of the present invention has an efficiency of at least 94%.

Dandl, Raphael A. (Oak Ridge, TN)

1980-01-01

170

Evacuated tubular or classical flat plate solar collectors?  

Directory of Open Access Journals (Sweden)

Full Text Available Evacuated tubular solar collectors are increasingly used all over the world due to their low coefficients of heat losses to the environment. They are presented as a device collecting much larger quantities of solar energy than is usually possible to obtain from typical flat collector. They have, however, unfavorable radiation transmissivity characteristics of transparent shield of absorber. It causes that the profits of energy gain at the operating conditions of typical solar system in our country only slightly dependent on the nature of the solar collectors applied. This article is an attempt to explain this phenomenon through theoretical considerations.

Zbyslaw Pluta

2011-01-01

171

Experimental investigation of comfort sensation and performance of radiant heating panel compared with conventional oil heater  

Energy Technology Data Exchange (ETDEWEB)

Portable heaters are normally small units designed to heat rooms and offices. These may include electric radiators, electric fan heaters, electric natural convection heaters such as oil heaters, portable gas heaters and kerosene heaters. The most common portable type of electrical heater is the oil-filled convector heater which involves transferring heat to the room occupants primarily by natural convection. For low temperature electric resistance wall segment heaters, also known as radiant panels, most of the heat is transferred directly to the room occupants by radiation. This paper presented an experimental investigation to evaluate the ability of radiant heater panels to produce thermal comfort for space occupants and the energy consumption in comparison with conventional oil convective heaters at different outside temperatures. The thermal comfort of individuals was analyzed in order to determine and characterize indoor thermal environments generated by each heating systems. The paper discussed the experimental methods, including experimental facilities, subjects features and experimental procedures. It was concluded that at 0 degrees Celsius and 10 degrees Celsius ambient temperature, two radiant panel heaters with a total capacity of 580 watts provided more comfort than an oil heater with 670 watt capacity. The energy savings was about 13.4 per cent. In addition, at 10 degrees Celsius, one heater with a capacity of 290 watts provided more comfort than an oil heater with 670 watts capacity. The energy savings was about 56.7 per cent. 11 refs., 3 tabs., 4 figs.

Ali, A.H.H.; Morsy, M.G.; Taha, I.S.; Hamza, M. [Assiut Univ., Assiut (Egypt). Dept. of Mechanical Engineering

2007-07-01

172

A solar collector design procedure for crop drying  

OpenAIRE

A design procedure was proposed for sizing solar-assisted crop-drying systems and assessing the combination of solar collector area and auxiliary energy needs that meets the requirements of the load. Two empirical correlations were compared for use with high thermal inertia solar collectors that are cheap and appropriate for rural areas. A case study as performed in the city of Campinas in southeastern Brazil. Grain drying with partial air heating by solar energy can provide an annual savings...

Santos, B. M.; Queiroz, M. R.; Borges, T. P. F.

2005-01-01

173

Evacuated tubular or classical flat plate solar collectors?  

OpenAIRE

Evacuated tubular solar collectors are increasingly used all over the world due to their low coefficients of heat losses to the environment. They are presented as a device collecting much larger quantities of solar energy than is usually possible to obtain from typical flat collector. They have, however, unfavorable radiation transmissivity characteristics of transparent shield of absorber. It causes that the profits of energy gain at the operating conditions of typical solar system in our co...

Zbyslaw Pluta

2011-01-01

174

21 CFR 880.5130 - Infant radiant warmer.  

Science.gov (United States)

... The infant radiant warmer is a device consisting of an infrared heating element intended to be placed over an infant to...heat. The device may also contain a temperature monitoring sensor, a heat output control mechanism, and an alarm...

2010-04-01

175

Energy-Efficient Sol-Gel Process for Production of Nanocomposite Absorber Coatings for Tubular Solar Thermal Collectors  

OpenAIRE

The energy efficiency of production processes for components of solar energy systems is an important issue. Other factors which are important for the production of products such as black selective solar coatings include production speed, cycle time and homogeneity of the coating, as well as the minimization of the quantity of the needed chemical precursors. In this paper a new energy efficient production process is presented for production of optically selective coatings for solar thermal abs...

Scartezzini, Jean-louis; Joly, Martin; Antonetti, Yann; Python, Martin; Gonzalez, Marina; Gascou, Thomas; Hessler, Ai?cha; Schueler, Andreas

2013-01-01

176

Error analysis of thermocouple measurements in the Radiant Heat Facility  

International Nuclear Information System (INIS)

The measurement most frequently made in the Radiant Heat Facility is temperature, and the transducer which is used almost exclusively is the thermocouple. Other methods, such as resistance thermometers and thermistors, are used but very rarely. Since a majority of the information gathered at Radiant Heat is from thermocouples, a reasonable measure of the quality of the measurements made at the facility is the accuracy of the thermocouple temperature data

177

Semen quality in welders exposed to radiant heat.  

OpenAIRE

Several studies suggest that welding is detrimental to the male reproductive system. Welding fume and radiant heat are of interest as possible causal factors. This study investigates semen quality and sex hormone concentrations among 17 manual metal arc alloyed steel welders with a moderate exposure to radiant heat (globe temperature ranging from 31.1 degrees to 44.8 degrees C), but without substantial exposure to welding fume toxicants. During exposure to heat the skin temperature in the gro...

Raymond, L. W.

1992-01-01

178

Radiant heat transfer of optically thick spherical shells through a layer of hot almost transparent plasma  

International Nuclear Information System (INIS)

A model of radiant heat exchange in a multilayer system comprising optically thick spherical shells with intermediate layers of high-temperature (hot) plasma is developed for effective solution of spherically-symmetric one-dimensional problems of radiation gasodynamics with simultaneous existence of optically thin and optically thick layers of substance. Radiation transport in optically thick layers in the suggested model is described in the known approximation of radiant thermal conductivity, but in this case integral boundary conditions including radiation effects of the given layer by volumetric radiation of optically thin plasma and weak radiation of the neighbouring optically thick layer (and self-radiation) are derived for equations of thermal conductivity. The effect of substance local heating by surface radiation of surrounding optically thick layers at the expense of partial absorption of this radiation by plasma is investigated in hot plasma. The equations of the model comply with the laws of energy conservation and they correspond to Kirchhoff law

179

Electron beam collector with a low back flow  

International Nuclear Information System (INIS)

Generation of a DC electron beam in the future Fermilab electron cooler [1] employs an electrostatic acceleration and a beam energy recovery, so that electrons are decelerated from the nominal energy of 4.3 MeV they have in the cooling section to few keV in the collector. Stable performance of this scheme requires a current loss (delta)I below 10 (micro)A at the beam current up to the nominal value of I = 0.5 A. One of sources of the loss is a back flow of secondary electrons from the beam collector. The paper discusses principles and performance of a collector with the low current loss. Electric and magnetic fields in the collectors used in existing electron coolers are axially symmetrical. For practically interesting parameters, such collectors can not provide (delta)I/I-4 because of the reversibility of trajectories in the collectors: a secondary electron with the kinetic energy equal to the energy of the primary one can come out of the collector following the trajectory of the ''parent'' electron. The back flow can be dramatically decreased if the reversibility is broken by a transverse magnetic field in the collector cavity. In our case, the field was formed by a system of permanent magnets. Several versions of the system were tested at a low-energy test bench. The first of them is optimized for operation without a longitudinal magnetic field. The transverse field is formed by two groups of 6 Nd-Fe-B square permanent magnets, mounted on both sides opermanent magnets, mounted on both sides of the collector and magnetized along the X-axis. Because the directions of magnetization in groups are opposite, the magnetic field in the vicinity of the Z-axis has a quadrupole configuration with the gradient of 10-15 G/cm. The field focuses electrons in X direction and defocuses in Y, so that the beam is absorbed on collector walls mainly along a narrow band near the plane X=0. The transverse field in this region, with the magnitude of 50-70 G, effectively confines secondary electrons. The only exception is electrons entering the collector with small Y offsets, which fly through the collector and hit its bottom. Because the transverse field strength near the bottom is low, the produced secondary electrons have a high probability of escaping from the collector. Measurements of the collector efficiency at various beam positions at the collector entrance, made with a low-current, small size beam, show a narrow band of the beam positions with high relative current losses (up to 1 · 10-3) near Y axis. At higher currents, when the beam size is comparable with the entrance opening, the beam cannot be shifted from the high-loss region, and the total efficiency is determined by the beam part overlapped with the band. The best relative current loss in the symmetric configuration is 1.5 · 10-5 at the beam current up to 0.5 A. To eliminate the effect, the magnets on one side of the collector were shifted along Z with respect to the second group. Arising asymmetry of the magnetic field results in a displacement of the high-loss band from the center and in decreasing of the relative losses down to (delta)I/I= 3 · 10-6 at the beam current of up to I=0.6A [2]. When the collector was used in a 1.2 MeV beam recirculation experiment at the collector voltage of Uc=4 kV, the maximum beam current of 0.9 A and (delta)I/I= (5-20) · 10-6 were demonstrated [3

180

A high performance porous flat-plate solar collector  

Science.gov (United States)

A solar collector employing a porous matrix as a solar absorber and heat exchanger is presented and its application in solar air heaters is discussed. The collector is composed of a metallic matrix with a porous surface which acts as a large set of cavity radiators; cold air flows through the matrix plate and exchanges heat with the thermally stratified layers of the matrix. A steady-state thermal analysis of the collector is used to determine collector temperature distributions for the cases of an opaque surface matrix with total absorption of solar energy at the surface, and a diathermanous matrix with successive solar energy absorption at each depth. The theoretical performance of the porous flat plate collector is shown to exceed greatly that of a solid flat plate collector using air as the working medium for any given set of operational conditions. An experimental collector constructed using commercially available, low cost steel wool as the matrix has been found to have thermal efficiencies from 73 to 86%.

Lansing, F. L.; Clarke, V.; Reynolds, R.

1979-01-01

181

Radiant heat testing of the H1224A shipping/storage container  

Energy Technology Data Exchange (ETDEWEB)

H1224A weapons containers have been used for years by the Departments of Energy and Defense to transport and store W78 warhead midsections. Although designed to protect the midsections only from low-energy impacts, a recent transportation risk assessment effort has identified a need to evaluate the container`s ability to protect weapons in more severe accident environments. Four radiant heat tests were performed: two each on an H1224A container (with a Mk12a Mod 6c mass mock-up midsection inside) and two on a low-cost simulated H1224A container (with a hollow Mk12 aeroshell midsections inside). For each unit tested, temperatures were recorded at numerous points throughout the container and midsection during a 4-hour 121{degrees}C (250{degrees}F) and 30-minute 1010{degrees}C (1850{degrees}F) radiant environment. Measured peak temperatures experienced by the inner walls of the midsections as a result of exposure to the high-temperature radiant environment ranged from 650{degrees} C to 980{degrees} C (1200{degrees} F to 1800{degrees}F) for the H1224A container and 770 {degrees} to 990 {degrees}C (1420{degrees} F to 1810{degrees}F) for the simulated container. The majority of both containers were completely destroyed during the high-temperature test. Temperature profiles will be used to benchmark analytical models and predict warhead midsection temperatures over a wide range of the thermal accident conditions.

Harding, D.C.; Bobbe, J.G.; Stenberg, D.R.; Arviso, M.

1994-05-01

182

Simulation of a solar collector array consisting of two types of solar collectors, with and without convection barrier  

DEFF Research Database (Denmark)

The installed area of solar collectors in solar heating fields is rapidly increasing in Denmark. In this scenario even relatively small performance improvements may lead to a large increase in the overall energy production. Both collectors with and without polymer foil, functioning as convection barrier, can be found on the Danish market. Depending on the temperature level at which the two types of collectors operate, one can perform better than the other. This project aimed to study the behavior of a 14 solar collector row made of these two different kinds of collectors, in order to optimize the composition of the row. Actual solar collectors available on the Danish market (models HT-SA and HT-A 35-10 manufactured by ARCON Solar A/S) were used for this analysis. To perform the study, a simulation model in TRNSYS was developed based on the Danish solar collector field in Braedstrup. A parametric analysis was carried out by modifying the composition of the row, in order to find both the energy and economy optimum.

Bava, Federico; Furbo, Simon

2015-01-01

183

ADVANCED HYBRID PARTICULATE COLLECTOR  

Energy Technology Data Exchange (ETDEWEB)

A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the U.S. Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in an entirely novel manner. The AHPC concept combines fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two methods, both in the particulate collection step and in transfer of dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emissions with conventional ESPs, and solves the problem of reentrainment and re-collection of dust in conventional baghouses. Phase I of the development effort consisted of design, construction, and testing of a 5.7-m{sup 3}/min (200-acfm) working AHPC model. Results from both 8-hr parametric tests and 100-hr proof-of-concept tests with two different coals demonstrated excellent operability and greater than 99.99% fine-particle collection efficiency. Since all of the developmental goals of Phase I were met, the approach was scaled up in Phase II to a size of 255 m{sup 3}/min (9000 acfm) (equivalent in size to 2.5 MW) and was installed on a slipstream at the Big Stone Power Plant. For Phase II, the AHPC at Big Stone Power Plant was operated continuously from late July 1999 until mid-December 1999. The Phase II results were highly successful in that ultrahigh particle collection efficiency was achieved, pressure drop was well controlled, and system operability was excellent. For Phase III, the AHPC was modified into a more compact configuration, and components were installed that were closer to what would be used in a full-scale commercial design. The modified AHPC was operated from April to July 2000. While operational results were acceptable during this time, inspection of bags in the summer of 2000 revealed some membrane damage to the fabric that appeared to be caused by electrical effects. Subsequently, extensive theoretical, bench-scale, and pilot-scale investigations were completed to find an approach to prevent bag damage without compromising AHPC performance. Results showed that the best bag protection and AHPC performance were achieved by using a perforated plate installed between the discharge electrodes and bags. This perforated-plate design was then installed in the 2.5-MW AHPC at Big Stone Power Plant in Big Stone City, South Dakota, and the AHPC was operated from March to June 2001. Results showed that the perforated-plate design solved the bag damage problem and offered even better AHPC performance than the previous design. All of the AHPC performance goals were met, including ultrahigh collection efficiency, high air-to-cloth ratio, reasonable pressure drop, and long bag-cleaning interval.

Ye Zhuang; Stanley J. Miller; Michelle R. Olderbak; Rich Gebert

2001-12-01

184

Super-radiant scattering of dispersive fields  

International Nuclear Information System (INIS)

Motivated by analogue models of classical and quantum field theory in curved spacetimes and their recent experimental realizations, we consider wave scattering processes of dispersive fields exhibiting two extra scattering channels. In particular, we investigate how standard super-radiant scattering processes are affected by subluminal or superluminal modifications of the dispersion relation. We analyse simple (1+1)-dimensional toy models based on fourth-order corrections to the standard second-order wave equation and show that low-frequency waves impinging on generic scattering potentials can be amplified during the process. In specific cases, by assuming a simple step potential, we determine quantitatively the deviations in the amplification spectrum that arise due to dispersion, and demonstrate that the amplification can be further enhanced due to the presence of extra scattering channels. We also consider dispersive scattering processes in which the medium where the scattering takes place is moving with respect to the observer and show that super-radiance can also be manifest in such situations. (paper)

185

Colored solar collectors - Annual report 2006  

Energy Technology Data Exchange (ETDEWEB)

The architectural integration of thermal solar collectors into buildings is often limited by their black color, and the visibility of tubes and corrugations of the absorber sheets. A certain freedom in color choice would be desirable, but the colored appearance should not cause an excessive degradation of the collector efficiency. Multilayered thin film interference filters on the collector glazing can produce a colored reflection, hiding the corrugated metal sheet, while transmitting the non-reflected radiation entirely to the absorber. These interference filters are designed and optimized by numerical simulation, and are manufactured by sol-gel dip-coating or magnetron sputtering. The novel colored glazed solar collectors will be ideally suited for architectural integration into buildings, e.g. as solar active glass facades. Due to the tunability of the refractive index, nanostructured materials such as SiO{sub 2}:TiO{sub 2} composites and porous SiO{sub 2} are very useful for application in multilayer interference stacks. Novel quaternary Mg-F-Si-O films exhibit a surprisingly low refractive index and are therefore promising candidates for highly transparent coatings on solar collector glazing. The nanostructure of these thin films is studied by transmission electron microscopy, while the optical constants are measured precisely by ellipsometry. For a convincing demonstration, sufficiently large samples of high quality are imperatively needed. The fabrication of nanocomposite SiO{sub 2}:TiO{sub 2} films has been demonstrated by sol-gel dip-coating of A4-sized glass panes. The produced coatings exhibit a colored reflection in combination with a high solar transmittance, a homogenous appearance, and are free of visible defects. Film hardening by UV exposure will result in speeding up the sol-gel process and saving energy, thereby reducing costs significantly. The infrastructure for UV-curing has been established. A UV C radiation source can now be attached to the dip-coater, which is placed in a UV-screened laminar flow chapel. An industrial partner for the prototype fabrication of colored collector glazing has been found. For a first attempt of industrial scale production, adapted multilayer designs have been proposed. First tests on the industrial magnetron sputtering equipment have shown encouraging results, but some adaptations are still needed. Possible ways of implementation of the novel colored solar collectors/solar facades are investigated and discussed with facade manufacturers and architects. (authors)

Schueler, A.; Chambrier, E. De; Roecker, Ch.; Scartezzini, J.-L.

2007-12-15

186

A detailed thermal model of a parabolic trough collector receiver  

International Nuclear Information System (INIS)

Parabolic trough collectors are made by bending a sheet of reflective material into a parabolic shape. A metal black pipe, covered with a glass tube to reduce heat losses, is placed along the focal line of the collector. The concentrated radiation reaching the receiver tube heats the fluid that circulates through it, thus transforming the solar radiation into useful heat. It is sufficient to use a single axis tracking of the sun and thus long collector modules are produced. In this paper a detailed thermal model of a parabolic trough collector is presented. The thermal analysis of the collector receiver takes into consideration all modes of heat transfer; convection into the receiver pipe, in the annulus between the receiver and the glass cover, and from the glass cover to ambient air; conduction through the metal receiver pipe and glass cover walls; and radiation from the metal receiver pipe and glass cover surfaces to the glass cover and the sky respectively. The model is written in the Engineering Equation Solver (EES) and is validated with known performance of existing collectors and subsequently is used to perform an analysis of the collector we are going to install at Archimedes Solar Energy Laboratory at the Cyprus University of Technology.

187

Sensitivity analysis of the thermal performance of radiant and convective terminals for cooling buildings  

DEFF Research Database (Denmark)

Heating and cooling terminals can be classified in two main categories: convective terminals (e.g. active chilled beam, air conditioning) and radiant terminals. The mode of heat transfer of the two emitters is different: the first one is mainly based on convection, whereas the second one is based on both radiation and convection. In order to characterise the advantages and drawbacks of the different terminals, steady-state simulations of a typical office room have been performed using four types of terminals (active chilled beam, radiant floor, wall and ceiling). A sensitivity analysis has been conducted to determine the parameters influencing their thermal performance the most. The air change rate, the outdoor temperature and the air temperature stratification have the largest effect on the cooling need (maintaining a constant operative temperature). For air change rates higher than 0.5 ACH, differences between terminals can be observed. Due to their higher dependency on the air change rate and outdoor temperature, convective terminals are generally less energy effective than radiant terminals. The global comfort level achieved by the different systems is always within the recommended range, but differences have been observed in the uniformity of comfort.

Le Dreau, Jerome; Heiselberg, Per

2014-01-01

188

Short-Term Solar Collector Power Forecasting  

DEFF Research Database (Denmark)

This paper describes a new approach to online forecasting of power output from solar thermal collectors. The method is suited for online forecasting in many applications and in this paper it is applied to predict hourly values of power from a standard single glazed large area flat plate collector. The method is applied for horizons of up to 42 hours. Solar heating systems naturally come with a hot water tank, which can be utilized for energy storage also for other energy sources. Thereby such systems can become an important part of energy systems with a large share of uncontrollable energy sources, such as wind power. In such a scenario online forecasting is a vital tool for optimal control and utilization of solar heating systems. The method is a two-step scheme, where first a non-linear model is applied to transform the solar power into a stationary process, which then is forecasted with robust time-adaptive linear models. The approach is similar to the one by Bacher et al. (2009), but contains additional effects due to differences between solar thermal collectors and photovoltaics. Numerical weather predictions provided by Danish Meteorological Institute are used as input. The applied models adapt over time enabling tracking of changes in the system and in the surrounding conditions, such as decreasing performance due to wear and dirt, and seasonal changes such as leaves on trees. This furthermore facilitates remote monitoring and check of the system.

Bacher, Peder; Madsen, Henrik

2011-01-01

189

A Self-Biasing Pulsed Depressed Collector  

International Nuclear Information System (INIS)

Depressed collectors have been utilized successfully for many years to improve the electrical efficiency of vacuum electron devices. Increasingly, pulsed, high-peak power accelerator applications are placing a premium on electrical efficiency. As RF systems are responsible for a large percentage of the overall energy usage at accelerator laboratories, methods to improve upon the state-of-the-art in pulsed high-power sources are desired. This paper presents a technique for self-biasing the stages in a multistage depressed collector. With this technique, the energy lost during the rise and fall times of the pulse can be recovered, separate power supplies are not needed, and existing modulators can be retrofitted. Calculations show that significant cost savings can be realized with the implementation of this device in high-power systems. In this paper, the technique is described along with experimental demonstration. (auth)

190

A Self-Biasing Pulsed Depressed Collector  

Energy Technology Data Exchange (ETDEWEB)

Depressed collectors have been utilized successfully for many years to improve the electrical efficiency of vacuum electron devices. Increasingly, pulsed, high-peak power accelerator applications are placing a premium on electrical efficiency. As RF systems are responsible for a large percentage of the overall energy usage at accelerator laboratories, methods to improve upon the state-of-the-art in pulsed high-power sources are desired. This paper presents a technique for self-biasing the stages in a multistage depressed collector. With this technique, the energy lost during the rise and fall times of the pulse can be recovered, separate power supplies are not needed, and existing modulators can be retrofitted. Calculations show that significant cost savings can be realized with the implementation of this device in high-power systems. In this paper, the technique is described along with experimental demonstration. (auth)

Kemp, Mark A.; Jensen, Aaron; Neilson, Jeff; /SLAC

2014-05-29

191

Design Support System for Parabolic Trough Solar Collector  

OpenAIRE

Parabolic Trough Collector (PTC) is special kind of heat exchanger that is able to transfer solar radiation energy to fluid medium that flow through it. Designing a PTC for a specific working condition requires determination of several parameters and referring to a number of design standards and handbooks. Hence, a design support system is required to determine the necessary parameters and simulate different working conditions. Although, a number of design support systems for solar collectors...

Woldeyohannes, Abraham D.; Cheng, Hoe K.; Woldemichael, Dereje E.; Lim Chye Ing

2012-01-01

192

Thermal Evaluation of a Solarus PV-T collector  

OpenAIRE

Low concentrator PV-T hybrid systems produce both electricity and thermal energy; this fact increases the overall efficiency of the system and reduces the cost of solar electricity. These systems use concentrators which are optical devices that concentrate sunlight on to solar cells and reduce expensive solar cell area. This thesis work deals with the thermal evaluation of a PV-T collector from Solarus.Firstly the thermal efficiency of the low concentrator collector was characterized for the ...

Haddi, Jihad

2013-01-01

193

Thermal Efficiency of Double Pass Solar Collector with Longitudinal Fins Absorbers  

OpenAIRE

Problem statement: One of the most important components of a solar energy system is the solar collector. The performances of double-pass solar collector with longitudinal fins absorbers are analyzed. Approach: The study involves a theoretical study to investigate the effect of mass flow rate, number and height of fins on efficiency, which involves steady-state energy balance equations on the longitudinal fins absorber of solar collectors. The theoretical solution procedure...

Ahmad Fudholi; Kamaruzzaman Sopian; Ruslan, Mohd H.; Othman, Mohd Y.; Muhammad Yahya

2011-01-01

194

Economical judge possibility uses solar collectors to warm service water and heating  

OpenAIRE

The sun-heated water has been used from before fossil fuels started to determine the direction of our power consumption. This article is focused on the assessing of the use of solar energy as one of inexhaustible resources that has multiple uses, including hot water service systems. Heating is rendered through solar collectors that permit to transform solar energy to warm water. We divide solar collectors into various groups but in principle they are medium temperature collectors and low temp...

Lívia Bodonská

2006-01-01

195

Radiant{trademark} Liquid Radioisotope Intravascular Radiation Therapy System  

Energy Technology Data Exchange (ETDEWEB)

RADIANT{trademark} is manufactured by United States Surgical Corporation, Vascular Therapies Division, (formerly Progressive Angioplasty Systems). The system comprises a liquid {beta}-radiation source, a shielded isolation/transfer device (ISAT), modified over-the-wire or rapid exchange delivery balloons, and accessory kits. The liquid {beta}-source is Rhenium-188 in the form of sodium perrhenate (NaReO{sub 4}), Rhenium-188 is primarily a {beta}-emitter with a physical half-life of 17.0 hours. The maximum energy of the {beta}-particles is 2.1 MeV. The source is produced daily in the nuclear pharmacy hot lab by eluting a Tungsten-188/Rhenium-188 generator manufactured by Oak Ridge National Laboratory (ORNL). Using anion exchange columns and Millipore filters the effluent is concentrated to approximately 100 mCi/ml, calibrated, and loaded into the (ISAT) which is subsequently transported to the cardiac catheterization laboratory. The delivery catheters are modified Champion{trademark} over-the-wire, and TNT{trademark} rapid exchange stent delivery balloons. These balloons have thickened polyethylene walls to augment puncture resistance; dual radio-opaque markers and specially configured connectors.

Eigler, N.; Whiting, J.; Chernomorsky, A.; Jackson, J.; Knapp, F.F., Jr.; Litvack, F.

1998-01-16

196

Use of local convective and radiant cooling at warm environment  

DEFF Research Database (Denmark)

The effect of four local cooling devices (convective, radiant and combined) on SBS symptoms reported by 24 subjects at 28 ?C and 50% RH was studied. The devices studied were: (1) desk cooling fan, (2) personalized ventilation providing clean air, (3) two radiant panels and (4) two radiant panels with one panel equipped with small fans. A reference condition without cooling was tested as well. The response of the subjects to the exposed conditions was collected by computerized questionnaires. The cooling devices significantly (p<0,05) improved subjects’ thermal comfort compared to without cooling. The acceptability of the thermal environment was similar for all cooling devices. The acceptability of air movement and PAQ increased when the local cooling methods were used. The best results were achieved with personalized ventilation and cooling fan. The minimal improvement in PAQ was reported when the radiant panel was used alone. The use of the local cooling devices led to increase of eye irritation. The reported SBS symptoms increased during the exposure time in all studied conditions, i.e. with and without cooling devices. The lowest prevalence of symptoms was with personalized ventilation and with radiant panel with attached fans, which also helped people to feel less fatigue. The SBS symptoms increased the most when the cooling fan, generating movement of polluted room air, was used.

Melikov, Arsen Krikor; Krejcirikova, Barbora

2012-01-01

197

Examination of operational dynamics of radiant ceiling panel  

Science.gov (United States)

Radiant ceiling panels can be used in large-volume halls, e.g. vehicle repair shops and markets, to heat the entire or specific zones of the enclosed space. The system with radiant panels may be of small water capacity when just one or several units are installed over selected zones to provide additional heating. Depending on dimensions of radiant ceiling panel, its mounting mode and the temperature of its feeding medium, various thermal conditions are created under such panel. Thermal effects are also affected by the mode of thermal or cooling power control and dynamics of such control for an individual radiant panel or a set of panels. The dynamics of attainable radiant ceiling panel capacity was investigated and used as the grounds to determine general requirements for time-domain automatic control programs and those for operation of the controllers. The results presented from the examinations carried out for water radiators are not intended to delineate the requirements for all automatic control loops for water radiators; they are aimed at attracting attention to issues to be considered when preparing the algorithm of automatic control in particular situations.

Dudkiewicz, Edyta; Jadwiszczak, Piotr; Je?owiecki, Janusz

2011-06-01

198

Studies of collectors, 9  

International Nuclear Information System (INIS)

Chelating surfactants bearing hydroxyaminocarbonyl and amino groups (RnAHx) and cotelomer-type surfactants bearing hydroxyaminocarbonyl and pyridyl groups (Ls-VP-Q-Hx) were prepared and applied as flotation collectors for a trace amount of uranium. The uranium in an aqueous solution of pH 4 - 8 and in seawater was floated more effectively by ion flotation using RnAHx or by foam fractionation using Ls-VP-Q-Hx, compared with alkylhydroxamic acid (RnHx) and telomers bearing hydroxyaminocarbonyl groups (Lo-Hx). The effective flotation was concluded to be due to the chelate effects between the two groups on the complex formation and to the HLB of the resulting complex. Furthermore, the uranium recoveries were examined by using a hydroxamic acid polymer (62Hx), a N-methylhydroxamic acid telomer (Ls5.6MHx), and its cotelomer (Ls3.2VP4.5MHx). (author)

199

LHCb Tag Collector  

International Nuclear Information System (INIS)

The LHCb physics software consists of hundreds of packages, each of which is developed by one or more physicists. When the developers have some code changes that they would like released, they commit them to the version control system, and enter the revision number into a database. These changes have to be integrated into a new release of each of the physics analysis applications. Tests are then performed by a nightly build system, which rebuilds various configurations of the whole software stack and executes a suite of run-time functionality tests. A Tag Collector system has been developed using solid standard technologies to cover both the use cases of developers and integration managers. A simple Web interface, based on an AJAX-like technology, is available. Integration with SVN and Nightly Build System, is possible via a Python API. Data are stored in a relational database with the help of an ORM (Object-Relational Mapping) library.

200

LHCb Tag Collector  

Science.gov (United States)

The LHCb physics software consists of hundreds of packages, each of which is developed by one or more physicists. When the developers have some code changes that they would like released, they commit them to the version control system, and enter the revision number into a database. These changes have to be integrated into a new release of each of the physics analysis applications. Tests are then performed by a nightly build system, which rebuilds various configurations of the whole software stack and executes a suite of run-time functionality tests. A Tag Collector system has been developed using solid standard technologies to cover both the use cases of developers and integration managers. A simple Web interface, based on an AJAX-like technology, is available. Integration with SVN and Nightly Build System, is possible via a Python API. Data are stored in a relational database with the help of an ORM (Object-Relational Mapping) library.

Fuente Fernández, Paloma; Clemencic, Marco; Cousin, Nicolas; LHCb Collaboration

2011-12-01

201

Thermal Performance of an Annealed Pyrolytic Graphite Solar Collector  

Science.gov (United States)

A solar collector having the combined properties of high solar absorptance, low infrared emittance, and high thermal conductivity is needed for applications where solar energy is to be absorbed and transported for use in minisatellites. Such a solar collector may be used with a low temperature differential heat engine to provide power or with a thermal bus for thermal switching applications. One concept being considered for the solar collector is an Al2O3 cermet coating applied to a thermal conductivity enhanced polished aluminum substrate. The cermet coating provides high solar absorptance and the polished aluminum provides low infrared emittance. Annealed pyrolytic graphite embedded in the aluminum substrate provides enhanced thermal conductivity. The as-measured thermal performance of an annealed pyrolytic graphite thermal conductivity enhanced polished aluminum solar collector, coated with a cermet coating, will be presented.

Jaworske, Donald A.; Hornacek, Jennifer

2002-01-01

202

AEROSOL PARTICLE COLLECTOR DESIGN STUDY  

Energy Technology Data Exchange (ETDEWEB)

A computational evaluation of a particle collector design was performed to evaluate the behavior of aerosol particles in a fast flowing gas stream. The objective of the work was to improve the collection efficiency of the device while maintaining a minimum specified air throughput, nominal collector size, and minimal power requirements. The impact of a range of parameters was considered subject to constraints on gas flow rate, overall collector dimensions, and power limitations. Potential improvements were identified, some of which have already been implemented. Other more complex changes were identified and are described here for further consideration. In addition, fruitful areas for further study are proposed.

Lee, S; Richard Dimenna, R

2007-09-27

203

Convective and radiative heat transfer in MHD radiant boilers  

Science.gov (United States)

A combined convection-gas radiation, two-zone flow model is formulated for study of the heat transfer characteristics of MHD radiant boilers. The radiative contributions of carbon dioxide, water vapor, potassium atoms, and slag particles are included in the formulation, and are determined by solving the radiation transport equation using the P1 approximation. The scattering and absorption cross sections of slag particles are calculated from Mie theory. The model is used to analyze the scale-up of heat transfer in radiant boilers with refractory thickness, wall emissivity, and boiler size under conditions of a gas composition and slag particle spectrum typical of coal-fired MHD combustion. A design procedure is suggested for sizing radiant boilers so as to achieve the required heat extraction rate and to provide a flow residence time that is adequate for decomposition of NO(x) to acceptable levels.

Im, K. H.; Ahluwalia, R. K.

1981-10-01

204

Convective and radiative heat transfer in MHD radiant boilers  

International Nuclear Information System (INIS)

A combined convection-gas radiation, two-zone flow model is formulated for study of the heat transfer characteristics of MHD radiant boilers. The radiative contributions of carbon dioxide, water vapor, potassium atoms, and slag particles are included in the formulation, and are determined by solving the radiation transport equation using the P1 approximation. The scattering and absorption cross section of slag particles are calculated from Mie theory. The model is used to analyze the scale-up of heat transfer in radiant boilers with refractory thickness, wall emissivity, and boiler size, under conditions of a gas composition and slag particle spectrum typical of coal-fired MHD combustion. A design procedure is suggested for sizing radiant boilers so as to achieve required heat extraction rate and to provide a flow residence time that is adequate for decomposition of NO/sub x/ to acceptable levels

205

Design package for concentrating solar collector panels  

Energy Technology Data Exchange (ETDEWEB)

Information used to evaluate the design of the Northrup concentrating collector is presented. Included are the system performance specifications, the applications manual, and the detailed design drawings of the collector. The Northrup concentrating solar collector is a water/glycol/working fluid type, dipped galvanized steel housing, transparent acrylic Fresnel lens cover, copper absorber tube, fiber glass insulation and weighs 98 pounds. The gross collector area is about 29.4/sup 2/ per collector. A collector assembly includes four collector units within a tracking mount array.

1978-08-01

206

Economical judge possibility uses solar collectors to warm service water and heating  

Directory of Open Access Journals (Sweden)

Full Text Available The sun-heated water has been used from before fossil fuels started to determine the direction of our power consumption. This article is focused on the assessing of the use of solar energy as one of inexhaustible resources that has multiple uses, including hot water service systems. Heating is rendered through solar collectors that permit to transform solar energy to warm water. We divide solar collectors into various groups but in principle they are medium temperature collectors and low temperature collectors. The work is directed also on the solar collector market. In our case the market is just at its initial stage as this technology is little known and costs of collectors are rather high, compared to our conditions, on average, they may grow up to 100,000 Slovac crowns per a family house. Because it is the only investment and the costs of operation are minimum throughout the entire collectors lifetime, from the economic point of view, it is a rather advantageous investment. Solar collectors are used in heating and also in hot service water systems in family houses, where they permit to lower costs for the consumption of many kinds of energies. In the hot service water system, solar collectors permit to lower the consumption by almost 70 %. This way of using the solar energy is very prospective and in future it will be used in various sectors

Lívia Bodonská

2006-09-01

207

Economical judge possibility uses solar collectors to warm service water and heating  

International Nuclear Information System (INIS)

The sun-heated water has been used from before fossil fuels started to determine the direction of our power consumption. This article is focused on the assessing of the use of solar energy as one of inexhaustible resources that has multiple uses, including hot water service systems. Heating is rendered through solar collectors that permit to transform solar energy to warm water. We divide solar collectors into various groups but in principle they are medium temperature collectors and low temperature collectors. The work is directed also on the solar collector market. In our case the market is just at its initial stage as this technology is little known and costs of collectors are rather high, compared to our conditions, on average, they may grow up to 100,000 Slovac crowns per a family house. Because it is the only investment and the costs of operation are minimum throughout the entire collectors lifetime, from the economic point of view, it is a rather advantageous investment. Solar collectors are used in heating and also in hot service water systems in family houses, where they permit to lower costs for the consumption of many kinds of energies. In the hot service water system, solar collectors permit to lower the consumption by almost 70 %. This way of using the solar energy is very prospective and in future it will be used in various sectors. (authors)

208

New concepts for solar collectors in 2030  

Energy Technology Data Exchange (ETDEWEB)

In 2030, solar energy is expected to cover the full energy demand of newly built houses. In addition, increasing standards for quality of living require that newly built houses offer increased comfort, while still being affordable. Current collector technology will not be able to meet all these requirements; hence, new collector concepts are required. This paper develops new concepts for the capture, conversion, and storage of solar energy with a focus on future integration in newly built houses. Industrial design engineering was used in the concept development, including an analysis of the field as well as a series of workshops. Out of several concepts, two were selected and elaborated. The first concept (aimed at 2015) is based on a passive house, and is able to fully provide the domestic energy use of both the user and the building itself. The second concept (aimed at 2030) integrates energy production, energy storage, building insulation, and an indoor climate system in durable, modular construction elements; the total energy production of this concept exceeds the total domestic energy use. This paper illustrates the concept development process and its results.

Bakker, M.; Van Helden, W. [ECN Efficiency and Infrastructure, Petten (Netherlands); Nijs, J.; Reinders, A. [University of Twente, Faculty of CTW, Department of Design, Production and Management, Enschede (Netherlands)

2009-01-15

209

Impact of different internal convection control strategies in a non-evacuated CPC collector performance  

OpenAIRE

Over the last decade the technological advances observed in solar collector materials, namely better spectrally selective absorber coatings and ultra clear glass covers, contribute to performance improvements and translate into higher operational temperature ranges with higher efficiency values. While the use of Evacuated Tube Collectors (ETCs) is becoming widespread in the thermal conversion of solar energy, non-evacuated solar collectors still hold advantages at manufacturing, reliability a...

Horta, Pedro; Henriques, J. C. C.; Pereira, M. Collares

2012-01-01

210

Theoretical analysis to investigate thermal performance of co-axial heat pipe solar collector  

Energy Technology Data Exchange (ETDEWEB)

The thermal performance of co-axial heat pipe solar collector which consist of a collector 15 co-axial heat pipes surrounded by a transparent envelope and which heat a fluid flowing through the condenser tubes have been predicted using heat transfer analytical methods. The analysis considers conductive and convective losses and energy transferred to a fluid flowing through the collector condenser tubes. The thermal performances of co-axial heat pipe solar collector is developed and are used to determine the collector efficiency, which is defined as the ratio of heat taken from the water flowing in the condenser tube and the solar radiation striking the collector absorber. The theoretical water outlet temperature and efficiency are compared with experimental results and it shows good agreement between them. The main advantage of this collector is that inclination of collector does not have influence on performance of co-axial heat pipe solar collector therefore it can be positioned at any angle from horizontal to vertical. In high building where the roof area is not enough the co-axial heat pipe solar collectors can be installed on the roof as well as wall of the building. The other advantage is each heat pipe can be topologically disconnected from the manifold. (orig.)

Azad, E. [Iranian Research Organization for Science and Technology (IROST), Advanced Materials and Renewable Energy Department, Tehran (Iran, Islamic Republic of)

2011-12-15

211

A system for the comparison of tools for the simulation of water-based radiant heating and cooling systems  

OpenAIRE

Low temperature heating and high temperature cooling systems such as thermally activated building systems (TABS) offer the chance to use low exergy sources, which can be very beneficial financially as well as ecologically when using renewable energy sources. The above has led to a considerable increase of water based radiant systems in modern buildings and a need for reliable simulation tools to predict the indoor environment and energy performance. This paper de...

Behrendt, Benjamin; Raimondo, Daniela; Zhang, Ye; Schwarz, Stephanie; Christensen, Jørgen Erik; Olesen, Bjarne W.

2012-01-01

212

Numerical Modelling of Non-similar Mixed Convection Heat and Species Transfer along an Inclined Solar Energy Collector Surface with Cross Diffusion Effects  

OpenAIRE

An analysis is performed to study thermo-diffusion and diffusion-thermo effects on mixed convection heat and mass transfer boundary layer flow along an inclined (solar collector) plate. The resulting governing equations are transformed and then solved numerically using the local nonsimilarity method and Runge-Kutta shooting quadrature. A parametric study illustrating the influence of thermal buoyancy parameter (ζ), Prandtl number (Pr), Schmidt...

Osman Anwar Bég; Ahmed Bakier; Ramachandra Prasad; Swapan Kumar Ghosh

2011-01-01

213

Improved Collectors for High Power Gyrotrons  

International Nuclear Information System (INIS)

High power gyrotrons are used for electron cyclotron heating, current drive and parasitic mode suppression in tokamaks for fusion energy research. These devices are crucial for successful operation of many research programs around the world, including the ITER program currently being constructed in France. Recent gyrotron failures resulted from cyclic fatigue of the copper material used to fabricated the collectors. The techniques used to collect the spent beam power is common in many gyrotrons produced around the world. There is serious concern that these tubes may also be at risk from cyclic fatigue. This program addresses the cause of the collector failure. The Phase I program successfully demonstrated feasibility of a mode of operation that eliminates the cyclic operation that caused the failure. It also demonstrated that new material can provide increased lifetime under cyclic operation that could increase the lifetime by more than on order of magnitude. The Phase II program will complete that research and develop a collector that eliminates the fatigue failures. Such a design would find application around the world.

214

Combined solar collector and storage systems  

Energy Technology Data Exchange (ETDEWEB)

The article discusses reasons why fossil-fuelled water heating systems are included in new houses but solar systems are not. The technology and market potential for evacuated tube systems and integral collector storage systems (ICSS) are explained. The challenge for the designers of ICSSWH has been how to reduce heat loss without compromising solar energy collection. A new concept for enhanced energy storage is described in detail and input/output data are given for two versions of ICSSWH units. A table compares the costs of ICSSWH in houses compared with other (i.e. fossil fuel) water heating systems.

Norton, B.; Smyth, M.; Eames, P.; Lo, S.N.G. [University of Ulster, Newtownabbey (United Kingdom). Centre for Sustainable Technologies

2000-07-01

215

Numerical 3-D heat flux simulations on flat plate solar collectors  

Energy Technology Data Exchange (ETDEWEB)

A transient 3-D mathematical model for solar flat plate collectors has been developed. The model is based on setting mass and energy balances on finite volumes. The model allows the comparison of different configurations: parallel tubes collectors (PTC), serpentine tube collectors (STC), two parallel plate collectors (TPPC), and other non-usual possibilities like the use of absorbent fluids with semitransparent or transparent plates. Transparent honeycomb insulation between plate and cover can also be modelled. The effect of temperature on the thermal properties of the materials has also been considered. The model has been validated experimentally with a commercial PTC. The model is a useful tool to improve the design of plate solar collectors and to compare different configurations. In order to show the capabilities of the model, the performance of a PTC collector with non-uniformity flow is analysed and compared with experimental data from literature with good agreement. (author)

Villar, N. Molero; Lopez, J.M. Cejudo; Munoz, F. Dominguez; Garcia, E. Rodriguez; Andres, A. Carrillo [Grupo de Energetica, Escuela Tecnica Superior de Ingenieros Industriales, UMA, Plaza El Ejido s/n, 29013 Malaga (Spain)

2009-07-15

216

Reactivities of some thiol collectors and their interactions with Ag (+1) ion by molecular modeling  

Science.gov (United States)

The most commonly used collectors for sulfide minerals in the mining industry are the thiol collectors for the recovery of these minerals from their associated gangues by froth flotation. For this reason, a great deal of attention has been paid to understand the attachment mechanism of thiol collectors to metal sulfide surfaces. The density functional theory (DFT) calculations at the B3LYP/3-21G* and B3LYP/6-31++G** levels were employed to propose the flotation responses of these thiol collectors, namely, diethyl dithiocarbamate, ethyl dithiocarbamate, ethyl dithiocarbonate, ethyl trithiocarbonate and ethyl dithiophosphate ions, and to study the interaction energies of these collectors with Ag (+1) ion in connection to acanthite (Ag 2S) mineral. The calculated interaction energies, ? E, were interpreted in terms of the highest occupied molecular orbital (HOMO) energies of the isolated collector ions. The results show that the HOMOs are strongly localized to the sulfur atoms and the HOMO energies can be used as a reactivity descriptor for the flotation ability of the thiol collectors. Using the HOMO and ? E energies, the reactivity order of the collectors is found to be (C 2H 5) 2NCS 2- > C 2H 5NHCS 2- > C 2H 5OCS 2- > C 2H 5SCS 2- > (C 2H 5O)(OH)PS 2-. The theoretically obtained results are in good agreement with the experimental data reported.

Yekeler, Hulya; Yekeler, Meftuni

2004-09-01

217

Field evaluation of performance of radiant heating/cooling ceiling panel system  

DEFF Research Database (Denmark)

As in many other countries in the world, Japan has witnessed an increased focus on low-energy buildings.For testing different engineering solutions for energy-efficient buildings, a low-energy building was builtat the University of Tokyo as an experimental pilot project. In this building, a radiant heating/coolingceiling panel system is used. However, no standard exists for the in situ performance evaluation of radiantheating/cooling ceiling systems; furthermore, no published database is available for comparison. Thus,this study aims to not only clarify the system performance but also to share our experience and our resultsfor them to serve as a reference for other similar projects. Here, the system performance in relation toits heating/cooling capacity and thermal comfort has been evaluated. The heat transfer coefficient fromwater to room was 3.7 W/(m2K) and 4.8 W/(m2K) for heating and cooling cases, respectively. The upwardheat flux from the panels was found to be as large as 30–40% of the water heating/cooling capacity; thiswould translate into heat loss in certain operating modes. Several proposals for reducing the upwardheat flux were discussed. The measurements also showed that a category B thermal environment wasobtained using the radiant ceiling heating/cooling system.© 2014 Elsevier B.V. All rights reserved.

Li, Rongling; Yoshidomi, Togo

2015-01-01

218

Clouds and the Earth's Radiant Energy System (CERES) algorithm theoretical basis document. volume 4; Determination of surface and atmosphere fluxes and temporally and spatially averaged products (subsystems 5-12); Determination of surface and atmosphere fluxes and temporally and spatially averaged products  

Science.gov (United States)

The theoretical bases for the Release 1 algorithms that will be used to process satellite data for investigation of the Clouds and the Earth's Radiant Energy System (CERES) are described. The architecture for software implementation of the methodologies is outlined. Volume 4 details the advanced CERES techniques for computing surface and atmospheric radiative fluxes (using the coincident CERES cloud property and top-of-the-atmosphere (TOA) flux products) and for averaging the cloud properties and TOA, atmospheric, and surface radiative fluxes over various temporal and spatial scales. CERES attempts to match the observed TOA fluxes with radiative transfer calculations that use as input the CERES cloud products and NOAA National Meteorological Center analyses of temperature and humidity. Slight adjustments in the cloud products are made to obtain agreement of the calculated and observed TOA fluxes. The computed products include shortwave and longwave fluxes from the surface to the TOA. The CERES instantaneous products are averaged on a 1.25-deg latitude-longitude grid, then interpolated to produce global, synoptic maps to TOA fluxes and cloud properties by using 3-hourly, normalized radiances from geostationary meteorological satellites. Surface and atmospheric fluxes are computed by using these interpolated quantities. Clear-sky and total fluxes and cloud properties are then averaged over various scales.

Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator); Baum, Bryan A.; Charlock, Thomas P.; Green, Richard N.; Lee, Robert B., III; Minnis, Patrick; Smith, G. Louis; Coakley, J. A.; Randall, David R.

1995-01-01

219

Process heat generation in industrial buildings using solar concentration collectors  

International Nuclear Information System (INIS)

One of the most promising and important applications of solar energy is in the area of process heat generation for industry. While the greater part of the effort in solar research has traditionally been spent on developing devices for domestic use, it has long been recognized that the industrial user has a far greater potential. Apart from the quantities of energy involved, the industrial user is a convenient one and particularly geared for solar energy utilization. The main limitation of the industrial user with regard to solar energy utilization is his need for steam - rather than hot water at temperatures below 100 degrees C. The common flat-plate collectors are inadequate for generating steam and other types of collectors, usually more expensive, have to be employed. This paper describes a study aimed at incorporating a solar collector of a particular design in the roof structure of an industrial building, thereby bringing down the cost. The particular feature of the collector, based on the SRTA Stationary Reflector/Tracking Absorber concept, is a stationary spherical mirror which focuses the solar rays on a small, cylinder-shaped tracking absorber. Industrial roofs are usually constructed of modular elements, mounted on a support structure. It has been suggested to combine the spherical mirror of the collector in the modular roof element, thus obtaining a roof which can serve at the same time as a solar collector. The advantages to doing this are many: The added antages to doing this are many: The added cost of the solar system is reduced since the roof itself provides the structure of its mirrors; the mirrors reduce the insulation requirements of the roof; optimum utilization of the roof area for solar energy collection can be achieved; the mirror surface can be renewed and refurbished in-situ, and there is no need to replace the entire mirror when its reflectivity decreases in time. (author)

220

Performance analysis of photovoltaic thermal (PVT) water collectors  

International Nuclear Information System (INIS)

Highlights: • Performances analysis of PVT collector based on energy efficiencies. • New absorber designs of PVT collectors were presented. • Comparison present study with other absorber collector designs was presented. • High efficiencies were obtained for spiral flow absorber. - Abstract: The electrical and thermal performances of photovoltaic thermal (PVT) water collectors were determined under 500–800 W/m2 solar radiation levels. At each solar radiation level, mass flow rates ranging from 0.011 kg/s to 0.041 kg/s were introduced. The PVT collectors were tested with respect to PV efficiency, thermal efficiency, and a combination of both (PVT efficiency). The results show that the spiral flow absorber exhibited the highest performance at a solar radiation level of 800 W/m2 and mass flow rate of 0.041 kg/s. This absorber produced a PVT efficiency of 68.4%, a PV efficiency of 13.8%, and a thermal efficiency of 54.6%. It also produced a primary-energy saving efficiency ranging from 79% to 91% at a mass flow rate of 0.011–0.041 kg/s

221

A solar collector design procedure for crop drying  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english A design procedure was proposed for sizing solar-assisted crop-drying systems and assessing the combination of solar collector area and auxiliary energy needs that meets the requirements of the load. Two empirical correlations were compared for use with high thermal inertia solar collectors that are [...] cheap and appropriate for rural areas. A case study as performed in the city of Campinas in southeastern Brazil. Grain drying with partial air heating by solar energy can provide an annual savings of 30% in fuel consumption for 1.80m² collector area during the drying of 1.2t of corn at 50ºC at a daily air rate of 1526.8 m³/day.

B. M., Santos; M. R., Queiroz; T. P. F., Borges.

2005-06-01

222

A Didactic Experiment and Model of a Flat-Plate Solar Collector  

Science.gov (United States)

We report on an experiment performed with a home-made flat-plate solar collector, carried out together with high-school students. To explain the experimental results, we propose a model that describes the heating process of the solar collector. The model accounts quantitatively for the experimental data. We suggest that solar-energy topics should…

Gallitto, Aurelio Agliolo; Fiordilino, Emilio

2011-01-01

223

A Generalized Coupon Collector Problem  

OpenAIRE

This paper provides analysis to a generalized version of the coupon collector problem, in which the collector gets $d$ distinct coupons each run and she chooses the one that she has the least so far. On the asymptotic case when the number of coupons $n$ goes to infinity, we show that on average $\\frac{n\\log n}{d} + \\frac{n}{d}(m-1)\\log\\log{n}+O(mn)$ runs are needed to collect $m$ sets of coupons. An efficient exact algorithm is also developed for any finite case to compute t...

Xu, Weiyu; Tang, Ao Kevin

2010-01-01

224

A Generalized Coupon Collector Problem  

CERN Document Server

This paper provides analysis to a generalized version of the coupon collector problem, in which the collector gets $d$ distinct coupons each run and she chooses the one that she has the least so far. On the asymptotic case when the number of coupons $n$ goes to infinity, we show that on average $\\frac{n\\log n}{d} + \\frac{n}{d}(m-1)\\log\\log{n}+O(mn)$ runs are needed to collect $m$ sets of coupons. An efficient exact algorithm is also developed for any finite case to compute the average needed runs exactly. Numerical examples are provided to verify our theoretical predictions.

Xu, Weiyu

2010-01-01

225

Large-scale solar thermal collector concepts  

Science.gov (United States)

Thermal collector could be used ultimately to power steamplant to produce electricity. Collector would consist of two major subsystems: (1) series of segmented tracking mirrors with two axes of rotation and (2) absorber mounted on centrally located tower.

Brantley, L. W., Jr.

1975-01-01

226

Advanced Tubular Evacuated Solar Collector Workshop, summary  

Science.gov (United States)

A summary of a workshop on advanced tubular evacuated solar collectors is presented. Workshop topics include stationary concentrating collectors, extrusion of glass tubes, selective surface coatings, reflectors, heat pipe absorbers, getters and outgassing, tube assembly and design and installation.

227

Dynamics and control of a solar collector system for near Earth object deflection  

International Nuclear Information System (INIS)

A solar collector system is a possible method using solar energy to deflect Earth-threatening near-Earth objects. We investigate the dynamics and control of a solar collector system including a main collector (MC) and secondary collector (SC). The MC is used to collect the sunlight to its focal point, where the SC is placed and directs the collected light to an asteroid. Both the relative position and attitude of the two collectors should be accurately controlled to achieve the desired optical path. First, the dynamical equation of the relative motion of the two collectors in the vicinity of the asteroid is modeled. Secondly, the nonlinear sliding-mode method is employed to design a control law to achieve the desired configuration of the two collectors. Finally, the deflection capability of this solar collector system is compared with those of the gravitational tractor and solar sail gravitational tractor. The results show that the solar collector is much more efficient with respect to deflection capability.

228

Cooling load calculation by the radiant time series method - effect of solar radiation models  

Energy Technology Data Exchange (ETDEWEB)

In this work was analyzed numerically the effect of three different models for solar radiation on the cooling load calculated by the radiant time series' method. The solar radiation models implemented were clear sky, isotropic sky and anisotropic sky. The radiant time series' method (RTS) was proposed by ASHRAE (2001) for replacing the classical methods of cooling load calculation, such as TETD/TA. The method is based on computing the effect of space thermal energy storage on the instantaneous cooling load. The computing is carried out by splitting the heat gain components in convective and radiant parts. Following the radiant part is transformed using time series, which coefficients are a function of the construction type and heat gain (solar or non-solar). The transformed result is added to the convective part, giving the instantaneous cooling load. The method was applied for investigate the influence for an example room. The location used was - 23 degree S and 51 degree W and the day was 21 of January, a typical summer day in the southern hemisphere. The room was composed of two vertical walls with windows exposed to outdoors with azimuth angles equals to west and east directions. The output of the different models of solar radiation for the two walls in terms of direct and diffuse components as well heat gains were investigated. It was verified that the clear sky exhibited the less conservative (higher values) for the direct component of solar radiation, with the opposite trend for the diffuse component. For the heat gain, the clear sky gives the higher values, three times higher for the peek hours than the other models. Both isotropic and anisotropic models predicted similar magnitude for the heat gain. The same behavior was also verified for the cooling load. The effect of room thermal inertia was decreasing the cooling load during the peak hours. On the other hand the higher thermal inertia values are the greater for the non peak hours. The effect of using walls with different thermal diffusivities attenuates and shifts the peaks of cooling load to later hours. Finally, for windows with glasses of different colors, thickness and films influences significantly the fenestration cooling loads. (author)

Costa, Alexandre M.S. [Universidade Estadual de Maringa (UEM), PR (Brazil)], E-mail: amscosta@uem.br

2010-07-01

229

Effect of collector components on the collection efficiency of tubular evacuated collectors with diffuse reflectors  

Science.gov (United States)

A calorimetric experimental technique and Monte-Carlo ray tracing theory have been used to assess the efficiencies of evacuated tubular collector arrays with diffuse reflectors, for various collector tube separations and collector-reflector distances. Efficiencies are also compared for collector tubes with and without antireflection layers on the glass envelopes, and for varying sunlight incidence in two different collector tube separations. All of the experimentally observed trends are predicted by ray tracing. Collector efficiency is found to strongly depend on collector tube separation.

Chow, S. P.; Harding, G. L.; Window, B.; Cathro, K. J.

1984-01-01

230

Analysis of radiant heat transfer in a BWR fuel assembly  

International Nuclear Information System (INIS)

A computer code 'CIDER' was developed which analyzes radiant heat transfer in a BWR fuel rod bundle under loss of coolant conditions. In the code, (1) a channel box and fuel rods are considered to be gray bodies, (2) reflection and absorption of radiation beams in the atmosphere is neglected, (3) a fuel rod is approximated by a regular polygonal rod, and (4) radiant heat flux is calculated considering circumferential temperature distribution on each fuel rod surface, which is determined from radial and circumferential heat conduction calculations in a fuel rod. It was found that the conventional model with uniform cladding temperature overestimated heat flux about 30% in a typical situation, or correspondingly underestimated the temperature rises. (Auth.)

231

Asymmetric Laser Radiant Cooling in Storage Rings  

CERN Document Server

Laser pulses with small spatial and temporal dimensions can interact with a fraction of the electron bunches circulating in Compton storage rings. We studied synchrotron dynamics of such bunches when laser photons scatter off from the electrons with energy higher than the synchronous energy. In this case of ‘asymmetric cooling', as shown theoretically, the stationary energy spread is much smaller than under conditions of regular scattering; the oscillations are damped faster. Coherent oscillations of large amplitude may be damped in one synchrotron period, which makes this method feasible for injection the bunches into a ring in the longitudinal phase space. The theoretical results are validated with simulations.

Bulyak, E V; Zimmermann, F

2011-01-01

232

Solid propellant combustion response to oscillatory radiant heat flux  

Science.gov (United States)

A progress report is given on a research project to use the microwave Doppler velocimeter technique to measure the combustion response to an oscillating thermal radiation source (CO2 laser). The test technique and supporting analyses are described, and the results are presented for an initial test series on the nonmetallized, composite propellant, Naval Weapons Center formulation A-13. It is concluded that in-depth transmission of radiant heat flux is not a factor at the CO2 laser wave length.

Strand, L. D.; Weil, M. T.; Cohen, N. S.

1989-01-01

233

Experimental Study on the Optical Performance of Evacuated Solar Collectors  

International Nuclear Information System (INIS)

This work has been carried out to find the ideal operating conditions for solar vacuum tube collectors which are widely used at present. Various types of solar collectors including a flat plate one were experimentally tested and examined to determine their thermal efficiencies and operating characteristics. Generally, solar vacuum tubes can be classified into two groups according to their design features. Of these, one is characterized by the insertion of a metallic device(such as a finned heat pipe) in an evacuated glass tube for the collection and transportation of solar energy. The other utilizes double glass tubes where the smaller one is contained inside the bigger one and soldered to each other after the small gap between them is evacuated. Both of these solar collectors are designed to minimize convection heat losses by removing the air which is in direct contact with the absorber surface. The performance of the former type can be readily analyzed by applying the relevant correlations developed for flat plate solar collectors. This has been demonstrated in the present study for the case of a solar collector where a heat pipe is inserted in an evacuated tube

234

IEA/SPS 500 kW distributed collector system  

Science.gov (United States)

Engineering studies for an International Energy Agency project for the design and construction of a 500 kW solar thermal electric power generation system of the distributed collector system (DCS) type are reviewed. The DCS system design consists of a mixed field of parabolic trough type solar collectors which are used to heat a thermal heat transfer oil. Heated oil is delivered to a thermocline storage tank from which heat is extracted and delivered to a boiler by a second heat transfer loop using the same heat transfer oil. Steam is generated in the boiler, expanded through a steam turbine, and recirculated through a condenser system cooled by a wet cooling tower.

Neumann, T. W.; Hartman, C. D.

1980-05-01

235

Air/liquid collectors : September 1997  

DEFF Research Database (Denmark)

This report determine efficiency equations for combined air/liquid solar collectors by measurements on to different air/liquid collectors. Equations which contain all relevant informations on the solar collectors. A simulation program (Kviksol) has been modified in order to be able to handle this kind of collectors. The modified simulation program has been used for the determination of the surplus in performance which solar heating systems with this type of solar collectors for combined preheating of ventilation air and domestic hot water will have. The simulation program and the efficiency equation will allow the manufactures to optimize this kind of systems.

Jensen, SØren Østergaard; Olesen, Ole

1997-01-01

236

Radiant smiles everywhere - before the Chernobyl accident  

International Nuclear Information System (INIS)

The business reports presented by the Federal German electric utilities for 1985 are almost all simply brillant. Electricity consumption has been going up, some of the utilities even can boast about rates kept constant over the year. But before the printed business reports could be presented to the meetings of shareholders, a nasty cloud threw a dark shadow over all the brilliant results. The Chernobyl accident made some of the hymns over the nuclear electricity increases and nuclear power in general sound rather queer. Could we do without this energy source. Substituting nuclear power would yearly require: 28 million t of oil, or 41 million t of hard coal, or 142 million t of browncoal, or 38 thousand million cubic metres of natural gas. Extrapolating current conditions and assuming best achievements, renewable energy sources might be able to meet 6 p.c. of the primary energy demands by the year 2000. (orig./HP)

237

A Concentrated Solar Power Unit Collector’s Efficiency under varied wind speeds  

Directory of Open Access Journals (Sweden)

Full Text Available Concentrated Solar Power (CSP harnesses the sun?s solar energy to produce electricity. This report provides a technical analysis of the potential for CSP to provide low cost renewable electricity in Bhopal (M.P. and outlines the impact of varied wind speeds on its collector?s efficiency. Yields of CSP Plants depend strongly on site-specific meteorological conditions. Meteorological parameters that can influence the performance of CSP plant are Direct Normal Irradiance (DNI, wind, ambient air temperature and humidity. The concentrated solar thermal power system constructed for this system follows that of conventional design of a parabolic concentrator with the receiver placed along the line between the centre of the concentrator and the sun. The concentrator receives approximately 1124.82W/m2 of solar insolation (dependent upon time of year, which is concentrated and reflected to the receiver. By concentrating the incoming radiation, the operating temperature of the system is increased significantly, and subsequently increases the efficiency of the conversion from sunlight to electricity. For the current system, with a concentration ratio of 495, the concentrator is theoretically capable of producing temperature upwards to 712 degrees centigrade. It was found that the collector (concentrator + receiver yields an efficiency of 95.6 percent. This study investigates the potential for our intervention to accelerate the deployment of small-scale concentrated solar power (CSP in various parts of Bhopal (M.P.

Ajay Vardhan

2013-10-01

238

Desiccant cooling using unglazed transpired solar collectors  

Science.gov (United States)

The use of unglazed solar collectors for desiccant regeneration in a solid desiccant cooling cycle was investigated because these collectors are lower in cost than conventional glazed flat-plate collectors. Using computer models, the performance of a desiccant cooling ventilation cycle integrated with either unglazed transpired collectors or conventional glazed flat-plate collectors was obtained. We found that the thermal performance of the unglazed system was lower than the thermal performance of the glazed system because the unglazed system could not take advantage of the heat of adsorption released during the dehumidification process. For a 3-ton cooling system, although the area required for the unglazed collector was 69 percent more than that required for the glazed collector, the cost of the unglazed collector array was 44 percent less than the cost of the glazed collector array. The simple payback period of the unglazed system was half of the payback period of the glazed collector when compared to an equivalent gas-fired system. Although the use of unglazed transpired collectors makes economic sense, some practical considerations may limit their use in desiccant regeneration.

Pesaran, A. A.; Wipke, K.

1992-05-01

239

Growth and solar energy conversion of Azolla sp., cultivated under four solar irradiance flux density; Crescimento e conversao da energia solar de Azolla sp. cultivada em quatro densidades do fluxo radiante  

Energy Technology Data Exchange (ETDEWEB)

Growth and solar energy conversion were studied in three Azolla species grown under four levels (30, 50, 70 and 100%) of solar radiation incidence under outdoor conditions. Under full sunlight, the specie A. microphylla showed higher crop growth rate, relative growth rate, net assimilation rate and efficiency of solar energy conversion than the other ones. (author). 8 figs., 23 refs.

Carvalho, E.F. de [Acre Univ., Rio Branco, AC (Brazil); Lopes, N.F. [Vicosa Univ., MG (Brazil). Dept. de Biologia Vegetal

1994-02-01

240

Glass heat pipe evacuated tube solar collector  

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.

McConnell, Robert D. (Lakewood, CO); Vansant, James H. (Tracy, CA)

1984-01-01

241

Performance Evaluation of a Nanofluid (CuO-H2O Based Low Flux Solar Collector  

Directory of Open Access Journals (Sweden)

Full Text Available As the fossil fuels are depleting continuously, we know that solar energy harvesting is a significant potential area for new research dimensions. Sun provides us about 1.9 x 108TWh/yr on the land, of which 1.3 x 105 TWh]/yr energy is used. In order to make much use of solar energy on the earth, solar energy harvesting into more usable form (e.g. heat or electricity by using solar energy collectors is important aspect. A solar collector [1] is a device which transfers the collected solar energy to a fluid passing in contact with it. The performance of collector does not only depends upon how effective the absorber is, but also on how effective are the heat transfer and thermal properties (e.g. thermal conductivity, heat capacity of the fluid which is being used. The absorption properties of the fluids generally used in solar collectors are very poor which in turn limits the efficiency of the solar collector. So, there is a need to use energy efficient heat transfer fluids for high efficiency and performance. A relatively new attempt has been made to increase the performance of the solar collector by using nanofluids. Recently developed a new class of working fluids called Nanofluids, found to be possessing better thermal properties over the hosting fluids, can be a good option in the solar collector [5]. In our research work the CuO-water based nanofluid has been tested in the solar collector and their performance is investigated. It has been found that efficiency if the solar collector is increased by 4-6% compared to water

Lal Kundan

2013-04-01

242

Thermal stability of premature infants during routine care under radiant warmers.  

Science.gov (United States)

The body temperatures of infants weighing less than 1500 g under radiant warmers during routine care were documented in the first week of life. Ten infants (median gestational age 28 weeks, median birthweight 913 g) were studied. During 30 nursing interventions (mean 9.2 minutes) mean oesophageal and foot temperature changed 0 degrees C and -0.11 degrees C, respectively. A radiant warmer may limit heat loss during interventions because of easy access and rapid radiant warmer responsiveness. PMID:8777664

Seguin, J. H.; Vieth, R.

1996-01-01

243

Dynamic Modeling and Validation of Radiant Ceiling Systems Coupled to its Environment  

OpenAIRE

This paper presents the results of a study performed in order to develop a dynamic model of radiant ceiling panels in heating or cooling modes coupled to its environment (fenestration, walls, internal loads and ventilation system). The model considers the radiant panels as a dynamic-state finned heat exchanger connected to a detailed lumped dynamic model of the building (R-C network). The behavior of the radiant ceiling system and the interactions with its environment has been experimentally ...

Fonseca, Ne?stor; Cuevas, Cristian; Lemort, Vincent

2010-01-01

244

Combination of solar collectors and ground-source heat pump for small buildings  

OpenAIRE

The combination of solar heat and ground-source heat pumps in dwellings gives opportunities for optimising the use of renewable energy sources and minimize the share of bought energy. Solar collectors in the system may give advantages for the operational conditions both for the solar collectors and for the heat pump. The aim of this project was to analyse different variables such as energy demand, building types, climate, geological conditions, system design and control. The study has been ca...

Kjellsson, Elisabeth; Hellstro?m, Go?ran; Perers, Bengt

2005-01-01

245

Development of a simulation tool to evaluate the performance of radiant cooling ceilings  

Energy Technology Data Exchange (ETDEWEB)

Considerable electrical energy used to cool nonresidential buildings equipped with All-Air Systems is drawn by the fans that transport the cool air through the thermal distribution system. Hydropic Cooling Systems have the potential to reduce the amount of air transported through the building by separating the tasks of ventilation and thermal conditioning. Due to the physical properties of water, Hydropic Cooling Systems can transport a given amount of thermal energy using less than 5% of the otherwise necessary fan energy. They are suited to the dry climates that are typical of California and been used for more than 30 years in hospital rooms. However, energy savings and peak-load characteristics have not yet been analyzed. Adequate guidelines for their design and control systems has prevented lack of their widespread application to other building types. Evaluation of theoretical performance of Hydropic Systems could be made by computer models. Energy analysis programs such as DOE-2 do not yet have the capacity to simulate Hydropic Cooling Systems. Scope of this project is developing a model that can accurately simulate the dynamic performance of Hydropic Radiant Cooling Systems. The model can calculate loads, heat extraction rates, room air temperature and room surface temperature distributions, and can be used to evaluate issues such as thermal comfort, controls, system sizing, system configuration and dynamic response. The model was created with the LBL Simulation Problem Analysis and Research Kernel (SPARK), which provides a methodology for describing and solving the dynamic, non-linear equations that correspond to complex physical systems. Potential for Hydropic Radiant Cooling Systems applications can be determined by running this model for a variety of construction types in different California climates.

Stetiu, C.; Feustel, H.E.; Winkelmann, F.C.

1995-06-01

246

Modeling Heat Flow In a Calorimeter Equipped With a Textured Solar Collector  

Science.gov (United States)

Heat engines are being considered for generating electric power for minisatellite applications, particularly for those missions in high radiation threat orbits. To achieve this objective, solar energy must be collected and transported to the hot side of the heat engine. A solar collector is needed having the combined properties of high solar absorptance, low infrared emittance, and high thermal conductivity. To test candidate solar collector concepts, a simple calorimeter was designed, manufactured, and installed in a bench top vacuum chamber to measure heat flow. In addition, a finite element analysis model of the collector/calorimeter combination was made to model this heat flow. The model was tuned based on observations from the as-manufactured collector/calorimeter combination. In addition, the model was exercised to examine other collector concepts, properties, and scale up issues.

Jaworske, Donald A.; Allen, Bradley J.

2001-01-01

247

Mathematical Modelling and Experimental Investigation of Collector Efficiency of a Thermosyphonic Solar Water Heating System  

Directory of Open Access Journals (Sweden)

Full Text Available The collector efficiency of a thermosyphonic solar water heating system was investigated theoretically and experimentally. Mathematical models were developed and used to predict the system performance. The solar collector with water pipes spreading across its width was also developed, tested and the theoretical results obtained agreed well with the experimental results. The collector efficiency is high especially around mid-day when the solar collector receives the highest energy. The results also reveal the dependency of the system performance on intensity of solar radiation and mass flow rate. Increase in both solar radiation and mass flow rate increases the collector efficiency. Maximum efficiencies of 72.8 and 70.4% were obtained from theoretical and experimental analyses, respectively, at optimum mass flow rate of 0.098 kg/s.

Bukola Olalekan Bolaji

2011-10-01

248

The implementation of the regulations on solar collectors in buildings  

OpenAIRE

The use of solar energy constitutes a great concern of national and international bodies, as a result of a strategic policy towards green energy consumption. The Portuguese regulations on building thermal behaviour and energy efficiency, recently enacted by the Portuguese Government, in line with the European Union Directive 2002/91/CE, have introduced the obligatory use of solar collector technology for hot water production applied to new building projects and to some important retrofit work...

Abreu, Isabel; Oliveira, Rui

2008-01-01

249

The implementation of regulations on solar collectors in buildings  

OpenAIRE

In the beginning of this decade, the Portuguese Program E4 – Energy Efficiency and Endogenous Energies have proposed an ambitious goal of 1 million m2 of solar collector area in Portugal until 2010. To cope with this, it was implemented in 2001 by Portuguese Government the National Program Solar Hot Water for Portugal (IP-AQSpP). The Portuguese new Thermal Regulations (RCCTE) opens to all constructions partners a new opportunity for implementing more strongly renewable energy technologies i...

Abreu, Maria Isabel; Oliveira, Rui

2008-01-01

250

Investigations on efficiencies of HT solar collectors for different flow rates and collector tilts  

DEFF Research Database (Denmark)

Two HT solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one solar collector is equipped with an ETFE foil between the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates and tilt. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rates are obtained. The calculated efficiencies are in good agreement with the measured efficiencies.

Chen, Ziqian; Perers, Bengt

2013-01-01

251

Terrestrial photovoltaic collector technology trends  

Science.gov (United States)

Following the path of space PV collector development in its early stages, terrestrial PV technologies based upon single-crystal silicon have matured rapidly. Currently, terrestrial PV cells with efficiencies approaching space cell efficiencies are being fabricated into modules at a fraction of the space PV module cost. New materials, including CuInSe2 and amorphous silicon, are being developed for lowering the cost, and multijunction materials for achieving higher efficiency. Large grid-interactive, tracking flat-plate power systems and concentrator PV systems totaling about 10 MW, are already in operation. Collector technology development both flat-plate and concentrator, will continue under an extensive government and private industry partnership.

Shimada, K.; Costogue, E.

1984-01-01

252

Photovoltaic thermal collectors. Almost commercial; PV-Thermische collectoren. Bijna marktrijp  

Energy Technology Data Exchange (ETDEWEB)

The title collector can produce heat and electricity. Research on such collectors is one of the main research themes at the unit Renewable Energy in the Built Environment (DEGO) of the Energy research centre of the Netherlands (ECN) in Petten, Netherlands. Market introduction is expected in the year 2004. [Dutch] Met een PV-Thermische collector wordt zonlicht omgezet in warmte en elektriciteit. Het onderzoek aan deze collectoren is een van de zwaartepunten van het onderzoek bij ECN-DEGO. De marktintroductie wordt verwacht in 2004.

Zondag, H.A.; Van Helden, W.G.J. [ECN Duurzame Energie in de Gebouwde Omgeving DEGO, Petten (Netherlands)

2002-12-01

253

Analysis of super-radiant Smith-Purcell emission  

International Nuclear Information System (INIS)

Smith-Purcell emission is studied for a system with no incident field or electromagnetic feedback mechanism other than what is provided by the grating itself. A model is developed that analyzes the interaction between the electron beam and the grating electromagnetic modes. The system of equations is solved numerically, demonstrating linear emitted power versus current at low current levels and super-radiant power emission at higher currents. These results are compared to the previously published experimental data, and the model is used to gain some understanding of the physical mechanisms at work

254

Radiant science, dark politics: a memoir of the nuclear age  

International Nuclear Information System (INIS)

The reviewer describes Radiant Science, Dark Politics: A Memoir of the Nuclear Age in contrast to a memoir by James R. Killian, Jr., a contemporary of Kamen. Kamen, co-discoverer of carbon-14 and a valued member of the Berkeley Radiation Laboratory, was fired in 1944 and blackballed as a security risk. Rehabilitated by the end of the war, his continued fight against political injustice through the McCarthy era colors the book and, for the reviewer, makes it self-serving. Kamen's later scientific work reflected his desire to work alone rather than in collaboration

255

The Siblings of the Coupon Collector  

OpenAIRE

The following variant of the collector's problem has attracted considerable attention relatively recently (see, e.g., N. Pintacuda 1980, D. Foata H. Guo-Niu and B. Lass 2001, D. Foata and D. Zeilberger 2003, I. Adler, S. Oren and S. Ross 2003, and S. Ross 2010): There is one main collector who collects coupons. Assume there are $N$ different types of coupons with, in general, unequal occurring probabilities. When the main collector gets a "double", she gives it to her older ...

Doumas, Aristides V.; Papanicolaou, Vassilis G.

2014-01-01

256

Design, Fabrication and Experimental Testing of Solar Parabolic Trough Collectors with Automated Tracking Mechanism  

OpenAIRE

This paper was concerned with an experimental study of parabolic trough collector’s with its sun tracking system designed and manufactured. To facilitate rapid diffusion and widespread use of solar energy, the systems should also be easy to install, operate and maintain. In order to improve the performance of solar concentrator, different geometries and different types of reflectors were evaluated with respect to their optical and energy conversion efficiency. To assure good performance and...

Venkatesh Reddy; Srinath T; Pradeep Kumar K V

2013-01-01

257

Development and preliminary evaluation of double roof prototypes incorporating RBS (radiant barrier system)  

Energy Technology Data Exchange (ETDEWEB)

Double-skin roof is known as a very effective way to reduce both the conduction and convection heat transfers from roof to the ceiling of building, on the other hand, RBS (radiant barrier system) is very effective in blocking the radiation heat transfer between roof and ceiling. In this study, prototypical double roofs inspired by the concepts of both double-skin structure and RBS technique was specifically designed to cut down the solar heat gain from roof. The effect of energy saving was experimentally measured. A double roof structure, formed by a roof plate and an aluminum foil-PP (polypropylene) board-RC slab, can achieve good performance of heat barrier and is highly recommended. (author)

Pei-Chi Chang [National Yunlin Univ. of Science and Technology, Taiwan (China). Graduate School of Engineering Science and Technology; Che-Ming Chiang [National Cheng-Kung Univ., Taiwan (China). Dept. of Architecture; Chi-Ming Lai [National Chung-Hsing Univ., Taiwan (China). Graduate Inst. of Rural Planning

2008-07-01

258

Nanofluid optical property characterization: towards efficient direct absorption solar collectors  

OpenAIRE

Abstract Suspensions of nanoparticles (i.e., particles with diameters < 100 nm) in liquids, termed nanofluids, show remarkable thermal and optical property changes from the base liquid at low particle loadings. Recent studies also indicate that selected nanofluids may improve the efficiency of direct absorption solar thermal collectors. To determine the effectiveness of nanofluids in solar applications, their ability to convert light energy to thermal energy must be known. That is, their a...

Otanicar Todd; Taylor Robert; Phelan Patrick; Adrian Ronald; Prasher Ravi

2011-01-01

259

Density function of radiant flux about perimeters of rectangular cross sections of channels in power plants  

International Nuclear Information System (INIS)

This article examines the density function of radiant flux on the sides of rectangular cross sections of channels in power plants filled with gaseous, hot, selectively radiating and absorbing combustion products of organic fueld. Relations are proposed for evaluating the radiant flux density function under these conditions

260

Hybrid photovoltaic/thermal (PV/T) collector coupled with a compound parabolic concentrator (CPC)  

Energy Technology Data Exchange (ETDEWEB)

Hybrid Photovoltaic/Thermal (PV/T) conversion is a relatively new and promising technology for the production of both electrical and thermal energy simultaneously. A number of theoretical and experimental studies have been reported in the past on PV/T systems with air and liquid as heat transfer fluid. Studies on PV/T collectors are being made at Indian Institute of Technology in collaboration with All India Council of Technical Education (AICTE), New Delhi. Earlier, present authors have carried out detailed simulation studies on PV/T air heating collectors and have shown that hybrid PV/T systems have great potential in terms of their system efficiencies. It is further envisaged that the efficiency of a hybrid PV/T collector can be enhanced by its effective coupling with a compound parabolic concentrator (CPC). In the present investigation a theoretical analysis has been presented to study the performance of a hybrid PV/T collector coupled with a CPC. In the design, several CPC troughs are combined in a single collector panel. The absorber of the hybrid PV/T collector under investigation consists of an array of solar cells for generation of electricity, while collector fluid circulating past the absorber provides useful thermal energy as in a conventional flat plate collector. In the analysis, it is assumed that solar cell efficiency can be represented by a linear decreasing function of its temperature. Energy balance equations have been developed for various components of the system. Based on the developed analysis both thermal and electrical performance of the system as a function of system design parameters are presented and discussed. Results have been presented to compare the performance of hybrid PV/T collector coupled with and without CPC.

Garg, H.P.; Adhikari, R.S.

1998-07-01

261

Numerical Analysis of a Radiant Heat Flux Calibration System  

Science.gov (United States)

A radiant heat flux gage calibration system exists in the Flight Loads Laboratory at NASA's Dryden Flight Research Center. This calibration system must be well understood if the heat flux gages calibrated in it are to provide useful data during radiant heating ground tests or flight tests of high speed aerospace vehicles. A part of the calibration system characterization process is to develop a numerical model of the flat plate heater element and heat flux gage, which will help identify errors due to convection, heater element erosion, and other factors. A 2-dimensional mathematical model of the gage-plate system has been developed to simulate the combined problem involving convection, radiation and mass loss by chemical reaction. A fourth order finite difference scheme is used to solve the steady state governing equations and determine the temperature distribution in the gage and plate, incident heat flux on the gage face, and flat plate erosion. Initial gage heat flux predictions from the model are found to be within 17% of experimental results.

Jiang, Shanjuan; Horn, Thomas J.; Dhir, V. K.

1998-01-01

262

Flow processes in a radiant tube burner: Combusting flow  

International Nuclear Information System (INIS)

Highlights: ? 3D combusting flow in an industrial radiant tube burner is modelled using the ANSYS-CFX CFD code. ? Results are validated against data from an industrial furnace (NO emissions within 7%). ? The flame is long and narrow with slight asymmetry. Mixing near the fuel injector is very effective. ? The recuperator section is reasonably effective, but design improvements are proposed. ? The design is vulnerable to eccentricities due to manufacturing or assembly tolerances. -- Abstract: This paper describes a study of the combustion process in an industrial radiant tube burner (RTB), used in heat treating furnaces, as part of an attempt to improve burner performance. A detailed three-dimensional Computational Fluid Dynamics model has been used, validated with experimental test furnace temperature and flue gas composition measurements. Simulations using the Eddy Dissipation combustion model with peak temperature limitation and the Discrete Transfer radiation model showed good agreement with temperature measurements in the inner and outer walls of the burner, as well as with flue gas composition measured at the exhaust (including NO). Other combustion and radiation models were also tested but gave inferior results in various aspects. The effects of certain RTB design features are analysed, and an analysis of the heat transfer processes within the burner is presented.

263

Temperature dependent capacity contribution of thermally treated anode current collectors in lithium ion batteries  

Science.gov (United States)

Metal current collectors, offering a good connection between the active materials and the external circuit, is an important component in a rechargeable lithium ion battery. Some necessary thermal treatment in the battery fabrication and assembly procedure results in current collectors with some non-negligible reversible energy capacities; however, these energy capacities were negligible in the previous references. In this research, for the first time, we investigated the influence of the thermal treatment of current collectors (such as copper foil and stainless steel disk) on energy capacities. Our results indicate that different current collector materials have different thermal treatment effects on their electrochemical performance. The non-negligible capacity contribution is closely related to the treatment temperature.

Kim, Tae Kwon; Li, Xifei; Wang, Chunlei

2013-01-01

264

Active solar collectors and their applications  

Energy Technology Data Exchange (ETDEWEB)

This book presents a clear, systematic overview of active solar thermal technologies, covering all the standard topics on solar energy and more. The author draws on a unified framework for all collector types based on elegant methods originally developed only for flat plates, such as the heat transfer factors of Hottel, Whillier and Bliss, the utilizability method and the f-chart. A spectrum of analytical tools is presented, from simple and approximate to complex and accurate. For example, the chapter on system analysis develops both shorthand methods and computer simulation. The book covers topics on the frontiers of research, including a comparison of the single-pass and multipass alternatives for the flow rate.

Rabl, A.

1985-01-01

265

Solar Thermal Power Plants with Parabolic-Trough Collectors  

Science.gov (United States)

Parabolic-trough collectors (PTC) are solar concentrating devices suitable to work in the 150°C- 400°C temperature range. Power plants based on this type of solar collectors are a very efficient way to produce electricity with solar energy. At present, there are eight commercial solar plants (called SEGS-II, III,.. IX) producing electricity with parabolic-trough collectors and their total output power is 340 MW. Though all SEGS plants currently in operation use thermal oil as a heat transfer fluid between the solar field and the power block, direct steam generation (DSG) in the receiver tubes is a promising option to reduce the cost of electricity produced with parabolic- trough power plants. Most of technical uncertainties associated to the DSG technology were studied and solved in the DISS project and it is expected that this new technology will be commercially available in a short term. In Spain, the Royal Decree No. 436/204 (March 12th , 2004) has defined a premium of 0,18€/kWh for the electricity produced by solar thermal power plants, thus promoting the installation of solar thermal power plants up to a limit of 200 MW. Due to the current legal and financial framework defined in Spain, several projects to install commercial solar power plants with parabolic-trough collectors are currently underway.

Zarza, E.; Valenzuela, L.; León, J.

2004-12-01

266

Greenhouse heating with a fresh water floating collector solar pond  

International Nuclear Information System (INIS)

The fresh water floating collector solar pond was investigated both experimentally and theoretically in a previous work, and it is now matched, by simulation, with the heat load requirements of a greenhouse. Results of the simulation indicate that such a pond is a potential energy source for greenhouse heating. This is especially true when the material properties are such that solar absorption and storage are enhanced. This paper reports that to demonstrate this point, three sets of collectors constructed with materials of different physical (radiation) properties were tested. One set is constructed of common materials which are readily available and are normally used as covers for greenhouses. The second set made of improved materials which are also available but have a smaller long-wave transmittance. The last set made of ideal material which additionally possesses selective radiation absorption properties. Collectors made of ideal materials make a superior solar pond; thus, manufacturing films with improved properties should become a worthwhile challenge for the agricultural polyethylene-films industry. Preliminary economic studies indicate that even with the low oil (<$20/Bbl) prices which exist between 1986-1989, the fresh water floating collectors solar pond provides an economically attractive alternative to the conventional oil-burning heating system. This is especially true in mild climate areas and when the large initial investment is justified by long-term gial investment is justified by long-term greenhouse utilization planning

267

Testing and thermal modeling of radiant panels systems as commissioning tool  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the results of a study performed to develop a thermal modeling of radiant panels systems to be used in situ, as diagnosis tool in commissioning processes to determine the main operating conditions of the system in cooling or heating mode. The model considers the radiant panels as a finned heat exchanger in dry regime. By using as inputs the ceiling and room dimensions, the radiant ceiling material properties and the measurements of air and water mass flow rates and temperatures, the model is able to calculate the radiant ceiling capacity, ceiling surface average temperature, water exhaust temperature and resultant temperature as a comfort indicator. The modeling proposed considers combined convection, perforation effect and a detailed radiative heat exchange method for radiant ceiling systems. An example of each system considered in this study is shown, illustrating the validation of the model. A sensitive analysis of the model is performed.

Fonseca Diaz, Nestor, E-mail: njfonseca@doct.ulg.ac.b [University of Liege Belgium, Thermodynamics Laboratory, Campus du Sart Tilman, Bat: B49, P33, B-4000 Liege (Belgium); Universidad Tecnologica de Pereira, Facultad de Ingenieria Mecanica, AA 97 Pereira (Colombia); Cuevas, Cristian [Universidad de Concepcion, Facultad de Ingenieria, Departamento de Ingenieria Mecanica, Casilla 160c Concepcion (Chile)

2010-12-15

268

Indoor test and long-term weathering effects on the thermal performance of the solar energy system (liquid) solar collector. [Marshall Space Flight Center solar test facility and solar simulator  

Science.gov (United States)

The procedures used and the results obtained during the evaluation test program on a liquid solar collector are presented. The narrow flat plate collector with reflective concentrating mirrors uses water as the working fluid. The double-covered collector weighs 137 pounds and has overall dimensions of about 35" by 77" by 6.75". The test program was conducted to obtain the following information: thermal performance data under simulated conditions, structural behavior under static load, and the effects of long term exposure to natural weathering.

1979-01-01

269

Onions and corn drying with solar collectors. Measurements at practical installations  

Energy Technology Data Exchange (ETDEWEB)

The use of air collectors to dry agricultural products is rising. Some projects throughout the world are mentioned. A description of a complete drying system is given. Two projects in the Netherlands are discussed. One project concerns an air collector on the roof of an agricultural industry which dries onions. The other project is an uncovered air collector on the roof of a corn-drying industry. Both systems operate satisfactory. It is concluded that for drying agricultural products a solar energy system can be an attractive alternative for a conventional air heater. 6 figs.

Van der Leun, C.J.; Blok, K.

1988-02-01

270

Thin-film flat-plate solar collectors for low-cost manufacture and installation  

Energy Technology Data Exchange (ETDEWEB)

A flat-plate solar energy collector design using thin-film plastics in both the absorber and glazing is described. The design approach proceeded in two steps. First, cost constraints on solar collectors were determined using reasonable economic projections. Second, engineering was applied only to those ideas which had hope of falling within those cost boundaries. The use of thin-film plastics appeared most attractive according to these criteria. The nature of the marketing and distribution network can be expected to have a strong impact on the final installed cost of the collector; the proposed design has characteristics which could make possible a reduced price markup.

Andrews, J.W.; Wilhelm, W.G.

1980-03-01

271

Theoretical and experimental investigations of Chinese evacuated tubular solar collectors  

DEFF Research Database (Denmark)

Four different marketed Chinese evacuated tubular solar collectors have been investigated both theoretically and experimentally. The advantages of the investigated solar collectors compared to normal flat plate collectors were elucidated.

Qin, Lin; Furbo, Simon

1999-01-01

272

21 CFR 876.5250 - Urine collector and accessories.  

Science.gov (United States)

...2010-04-01 false Urine collector and accessories. 876.5250 Section 876.5250... § 876.5250 Urine collector and accessories. (a) Identification. A urine collector and accessories is a device intended to collect...

2010-04-01

273

An improved thermal and electrical model for a solar photovoltaic thermal (PV/T) air collector  

International Nuclear Information System (INIS)

In this paper, an attempt is made to investigate the thermal and electrical performance of a solar photovoltaic thermal (PV/T) air collector. A detailed thermal and electrical model is developed to calculate the thermal and electrical parameters of a typical PV/T air collector. The thermal and electrical parameters of a PV/T air collector include solar cell temperature, back surface temperature, outlet air temperature, open-circuit voltage, short-circuit current, maximum power point voltage, maximum power point current, etc. Some corrections are done on heat loss coefficients in order to improve the thermal model of a PV/T air collector. A better electrical model is used to increase the calculations precision of PV/T air collector electrical parameters. Unlike the conventional electrical models used in the previous literature, the electrical model presented in this paper can estimate the electrical parameters of a PV/T air collector such as open-circuit voltage, short-circuit current, maximum power point voltage, and maximum power point current. Further, an analytical expression for the overall energy efficiency of a PV/T air collector is derived in terms of thermal, electrical, design and climatic parameters. A computer simulation program is developed in order to calculate the thermal and electrical parameters of a PV/T air collector. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Finally noted in the previous literature. Finally, parametric studies have been carried out. Since some corrections have been down on thermal and electrical models, it is observed that the thermal and electrical simulation results obtained in this paper is more precise than the one given by the previous literature. It is also found that the thermal efficiency, electrical efficiency and overall energy efficiency of PV/T air collector is about 17.18%, 10.01% and 45%, respectively, for a sample climatic, operating and design parameters.

274

Finite-elements modeling of radiant heat transfers between mobile surfaces; Modelisation par elements finis de transferts radiatifs entre surfaces mobiles  

Energy Technology Data Exchange (ETDEWEB)

In the numerical modeling of thermal industrial problems, radiant heat transfers remain difficult to take into account and require important computer memory and long computing time. These difficulties are enhanced when radiant heat transfers are coupled with finite-elements diffusive heat transfers because finite-elements architecture is complex and requires a lot of memory. In the case of radiant heat transfers along mobile boundaries, the methods must be optimized. The model described in this paper concerns the radiant heat transfers between diffuse grey surfaces. These transfers are coupled with conduction transfers in the limits of the diffusive opaque domain. 2-D and 3-D geometries are analyzed and two configurations of mobile boundaries are considered. In the first configuration, the boundary follows the deformation of the mesh, while in the second, the boundary moves along the fixed mesh. Matter displacement is taken into account in the term of transport of the energy equation, and an appropriate variation of the thermophysical properties of the transition elements between the opaque and transparent media is used. After a description of the introduction of radiative limit conditions in a finite-elements thermal model, the original methods used to optimize calculation time are explained. Two examples of application illustrate the approach used. The first concerns the modeling of radiant heat transfers between fuel rods during a reactor cooling accident, and the second concerns the study of heat transfers inside the air-gap of an electric motor. The method of identification of the mobile surface on the fixed mesh is described. (J.S.) 12 refs.

Daurelle, J.V.; Cadene, V.; Occelli, R. [Universite de Provence, 13 - Marseille (France)

1996-12-31

275

Evaluation of Test Method for Solar Collector Efficiency  

OpenAIRE

The test method of the standard EN12975-2 (European Committee for Standardization, 2004) is used by European test laboratories to determine the efficiency of solar collectors. In the test methods the mean solar collector fluid temperature in the solar collector, Tm is determined by the approximated equation where Tin is the inlet temperature to the collector and Tout is the outlet temperature from the collector. The specific heat of the solar collector fluid is in the test method as an approx...

Fan, Jianhua; Shah, Louise Jivan; Furbo, Simon

2012-01-01

276

Coloured solar collectors. Phase II : from laboratory samples to collector prototypes. Final report  

Energy Technology Data Exchange (ETDEWEB)

This illustrated final report for the Swiss Federal Office of Energy (SFOE) deals with the second phase of a project concerning the architectural integration of glazed solar collectors into the facades of buildings for heat production. The factors that limit the integration of photovoltaic panels in facades are discussed. The authors state that, for a convincing demonstration, sufficiently large samples and high quality levels are needed. The sol-gel deposition of the multi-layered coatings on A4-sized glass panes demonstrated in the laboratory by EPFL-LESO are discussed. The coatings produced exhibit a coloured reflection in combination with a high solar transmittance, a homogenous appearance, and are free of visible defects. Film hardening by UV exposure is discussed: This should result in the speeding up of the sol-gel process and thus save energy, thereby significantly reducing costs. Collaboration with industry is discussed in which full-scale glass panes are to be coated with novel multiple layers. The novel glazing is to be integrated into first prototype collectors. The manufacturing and test processes for the prototypes manufactured are discussed in detail.

Schueler, A.; Roecker, Ch.; Chambrier, E. de; Munari Probst, M.

2007-07-01

277

Comparação dos métodos de Atenuação de Energia Radiante e Titulométrico para a determinação de Etanol no sangue - DOI: 10.4025/actascihealthsci.v25i2.2165 A comparison of Radiative Energy Attenuation and Titrimetric methods for the analysis of ethanol in blood - DOI: 10.4025/actascihealthsci.v25i2.2165  

Directory of Open Access Journals (Sweden)

Full Text Available A determinação de álcool no sangue foi avaliada através da comparação de duas técnicas analíticas, o método de atenuação de energia radiante (AER e o método titulométrico (TIT. A sensibilidade do AER foi de 0,4g/L e por TIT de 0,1g/L. A curva padrão de etanol foi linear até 2,5g/L e 4,0g/L para os métodos AER e TIT, respectivamente. O coeficiente de variação intra-série foi de 1,5% a 3,9% e de 0,6% a 3,2%, sendo que o coeficiente de variação inter-série foi de 2,5% a 12,8% e de 0% a 3,3% para os métodos AER e TIT, respectivamente. Os testes de recuperação apresentaram os seguintes resultados, 105% para o método AER e 88% para o método TIT. Em 70 amostras estudadas, o coeficiente de correlação (r foi de 0,9681 e o resultado do teste-t de Student foi de -1,294, demonstrando que os métodos se correlacionam bem.The alcohol determination in the blood was evaluated through the comparison of two analytical techniques, the method of radiative energy attenuation (REA and the chemical titration method (TIT. The sensibility of REA was 0.4g/L and of TIT was 0.1g/L. The curve standard of etanol was linear up to 2.5g/L and 4.0g/L for methods REA and TIT, respectively. The coefficient of variation was 1.5% to 3.9% and 0.6% to 3.2% in the same day, and day-to-day coefficient of variation was 2.5% to 12.8% and 0% to 3.3% for methods REA and TIT, respectively. The tests of recovery presented the following results, 105% for REA and 88% for TIT. In 70 studied samples, the coefficient of correlation (r was 0,9681 and the result of the test-t of Student was -1,294.

Miguel Machinski Junior

2003-04-01

278

Evaluation of the potential of optical switching materials for overheating protection of thermal solar collectors - Final report  

Energy Technology Data Exchange (ETDEWEB)

Providing renewable energy for domestic hot water production and space heating, thermal solar collectors are more and more widespread, and users' expectations with respect to performance and service lifetime are rising continuously. The durability of solar collector materials is a critical point as the collector lifetime should be at least 25 years. Overheating and the resulting stagnation of the collector is a common problem with solar thermal systems. During stagnation high temperatures lead to water evaporation, glycol degradation, and stresses in the collector with increasing pressure. Special precautions are necessary to release this pressure; only mechanical solutions exist nowadays. Additionally, the occurring elevated temperatures lead to degradation of the materials that compose collectors: seals, insulation materials, and also the selective coating which is the most important part of the collector. A promising way to achieve active cooling of collectors without any mechanical device for pressure release or collector emptying is to produce a selective coating which is able to switch its optical properties at a critical temperature Tc. An optical switch allows changing the selective coating efficiency; the goal is to obtain a coating with a poor selectivity above Tc (decreasing of absorptance, increasing of emittance). Obtaining self-cooling collectors will allow increasing collector surfaces on facades and roofs in order to get high efficiency and hot water production during winter without inconvenient overheating during summer. Optical switching of materials can be obtained by many ways. Inorganic and organic thermochromic compounds, and organic thermotropic coatings are the main types of switching coatings that have been studied at EPFL-LESO-PB. Aging studies of organic thermochromic paints fabricated at EPFL suggest that the durability of organic compounds might not be sufficient for glazed metallic collectors. First samples of inorganic coatings showing thermochromic switching behaviour have been produced at EPFL. These coatings switch from a semiconducting to a metallic state at critical temperatures around 65 {sup o}C, as indicated by a resistivity change of typically three orders of magnitude. (author)

Huot, G.; Roecker, Ch.; Schueler, A.

2008-01-15

279

Reactivities of some thiol collectors and their interactions with Ag (+1) ion by molecular modeling  

Energy Technology Data Exchange (ETDEWEB)

The most commonly used collectors for sulfide minerals in the mining industry are the thiol collectors for the recovery of these minerals from their associated gangues by froth flotation. For this reason, a great deal of attention has been paid to understand the attachment mechanism of thiol collectors to metal sulfide surfaces. The density functional theory (DFT) calculations at the B3LYP/3-21G* and B3LYP/6-31++G** levels were employed to propose the flotation responses of these thiol collectors, namely, diethyl dithiocarbamate, ethyl dithiocarbamate, ethyl dithiocarbonate, ethyl trithiocarbonate and ethyl dithiophosphate ions, and to study the interaction energies of these collectors with Ag (+1) ion in connection to acanthite (Ag{sub 2}S) mineral. The calculated interaction energies, {delta}E, were interpreted in terms of the highest occupied molecular orbital (HOMO) energies of the isolated collector ions. The results show that the HOMOs are strongly localized to the sulfur atoms and the HOMO energies can be used as a reactivity descriptor for the flotation ability of the thiol collectors. Using the HOMO and {delta}E energies, the reactivity order of the collectors is found to be (C{sub 2}H{sub 5}){sub 2}NCS{sub 2}{sup -} > C{sub 2}H{sub 5}NHCS{sub 2}{sup -} > C{sub 2}H{sub 5}OCS{sub 2}{sup -} > C{sub 2}H{sub 5}SCS{sub 2}{sup -} > (C{sub 2}H{sub 5}O)(OH)PS{sub 2}{sup -}. The theoretically obtained results are in good agreement with the experimental data reported.

Yekeler, Hulya; Yekeler, Meftuni

2004-09-15

280

Comparative Study on Solar Collector’s Configuration for an Ejector-Refrigeration Cycle  

Directory of Open Access Journals (Sweden)

Full Text Available Solar collector’s configuration plays important role on solar-powered refrigeration systems to work as heat source for generator. Three types of solar collector consisting of flat plate, evacuated tube, and compound parabolic solar collectors are compared to investigate their performances. The performances consist of the behavior of heat which can be absorbed by the collectors, heat loss from the collectors and outlet temperature of working fluid at several slopes of the solar collectors. The new accurate analysis method of heat transfer is conducted to predict the performance of the solar collectors. The analysis is based on several assumptions, i.e. sky condition at Bandung is clear and not raining from 08.00 until 17.00 and thermal resistance at cover and absorber plate is negligible. The numerical calculation results confirm that performance of the evacuated tubes solar collector at the same operating conditions is higher than the others. For the case of an evacuated-tubes solar collector system with aperture area of 3.5 m2, the maximum heat which can be absorbed is 3992 W for the highest solar intensity of 970 W/m2 at 12.00 and horizontal position of the solar collector. At this condition, the highest outlet temperature of water is 347.15 K with mass flow rate 0.02 kg/s and inlet temperature 298 K.

Raffles Senjaya

2008-05-01

281

The Antiproton Collector and Antiproton Accumulator  

CERN Multimedia

The Antiproton Collector (AC) and Antiproton Accumulator (AA). The addition of a collector to the Antiproton Accumulator in 1987 paved the way for a ten-fold increase in antiproton production at CERN. In 1998 these machines were dismantled and replaced with the Antiproton Decellerator (AD).

1987-01-01

282

Modular test system for solar collectors  

Science.gov (United States)

Portable, recirculating-water-flow, and temperature-control device is used with solar simulator and actual sunlight to test and evaluate several solar-collector panel coatings, panel designs, and scaled-down collector subsystems. System can be pressurized to prevent boiling and allows operation above 100 degrees Centigrade.

Dolan, F. J.

1977-01-01

283

A ferromagnetic collector for magnetic separation  

International Nuclear Information System (INIS)

A ferromagnetic collector for high gradient magnetic separation formed from steels having a chromium content of at least 17% by weight and a carbon content not exceeding 0.03% by weight. Such steels are resistant to attack by acid and are therefore suitable as magnetic collectors in filters employed in acidic environments. (author)

284

Design and beam transport simulations of a multistage collector for the Israeli EA-FEM  

Science.gov (United States)

A four stage asymmetric type depressed collector has been designed for the Israeli mm-wave FEM that is driven by a 1.4 MeV, 1.5 A electron beam. After leaving the interaction section the spent beam has an energy spread of 120 keV and 75 ? mm mrad normalized beam emittance. Simulations of the beam transport system from the undulator exit through the decelerator tube into the collector have been carried out using EGUN and GPT codes. The latter has also been employed to study trajectories of the primary and scattered particles within the collector, optimizing the asymmetrical collector geometry and the electrode potentials at the presence of a deflecting magnetic field. The estimated overall system and collector efficiencies reach 50% and 70%, respectively, with a beam recovery of 99.6%. The design is aimed to attain millisecond long pulse operation and subsequently 1 kW average power. Simulation results are implemented in a mechanical design that leads to a simple, cost efficient assembly eliminating ceramic insulator rings between collector stages and the associated brazing in the manufacturing process. Instead, each copper plate is supported by insulating posts and freely displaceable within the vacuum chamber. We report on the simulation results of the beam transport and recovery systems and on the mechanical aspects of the multistage collector design.

Tecimer, M.; Canter, M.; Efimov, S.; Gover, A.; Sokolowski, J.

2001-12-01

285

Design and beam transport simulations of a multistage collector for the Israeli EA-FEM  

Energy Technology Data Exchange (ETDEWEB)

A four stage asymmetric type depressed collector has been designed for the Israeli mm-wave FEM that is driven by a 1.4 MeV, 1.5 A electron beam. After leaving the interaction section the spent beam has an energy spread of 120 keV and 75 {pi} mm mrad normalized beam emittance. Simulations of the beam transport system from the undulator exit through the decelerator tube into the collector have been carried out using EGUN and GPT codes. The latter has also been employed to study trajectories of the primary and scattered particles within the collector, optimizing the asymmetrical collector geometry and the electrode potentials at the presence of a deflecting magnetic field. The estimated overall system and collector efficiencies reach 50% and 70%, respectively, with a beam recovery of 99.6%. The design is aimed to attain millisecond long pulse operation and subsequently 1 kW average power. Simulation results are implemented in a mechanical design that leads to a simple, cost efficient assembly eliminating ceramic insulator rings between collector stages and the associated brazing in the manufacturing process. Instead, each copper plate is supported by insulating posts and freely displaceable within the vacuum chamber. We report on the simulation results of the beam transport and recovery systems and on the mechanical aspects of the multistage collector design.

Tecimer, M. E-mail: tecimer@post.tau.ac.il; Canter, M.; Efimov, S.; Gover, A.; Sokolowski, J

2001-12-21

286

Performance of solar collectors under low temperature conditions : Measurements and simulations results  

DEFF Research Database (Denmark)

The performance of four solar thermal collectors (flat plate, evacuated tube, unglazed with rear insulation and unglazed without rear insulation) was experimentally measured and simulated for temperatures below ambient. The influence of several parameters (e.g. collector inlet temperature, air temperature, condensation) is investigated under different operating conditions (day and night). Under some conditions condensation might occur and heat gains could represent up to 55% of the total unglazed collector energy by night. Two TRNSYS collector models including condensation heat gains are also evaluated and results compared to experimental measurements. A mathematical model is also under development to include, in addition to the condensation phenomena, the frost, the rain and the long-wave radiation gains/losses on the rear of the solar collector. While the potential gain from rain was estimated to be around 2%, frost heat gains were measured to be up to 40% per day, under specific conditions. Overall, results have shown that unglazed collectors are more efficient than flat plate or evacuated tube collectors at low operation temperatures or for night conditions, making them more suitable for heat pump applications.

Bunea, Mircea; Eicher, Sara

287

An investigation on the performance characteristics of solar flat plate collector with different selective surface coatings  

Directory of Open Access Journals (Sweden)

Full Text Available In the present work, investigations are made to study performance characteristics of solar flat plate collector with different selective surface coatings. Flat plate collector is one of the important solar energy trapping device which uses air or water as working fluid. Of the many solar collector concepts presently being developed, the relative simple flat plate solar collector has found the widest application so far. Its characteristics are known, and compared with other collector types, it is the easiest and least expensive to fabricate, install, and maintain. Moreover, it is capable of using both the diffuse and the direct beam solar radiation. For residential and commercial use, flat plate collectors can produce heat at sufficiently high temperatures to heat swimming pools, domestic hot water, and buildings; they also can operate a cooling unit, particularly if the incident sunlight is increased by the use of reflector. Temperatures up to 70 oC are easily attained by flat plate collectors. With very careful engineering using special surfaces, reflectors to increase the incident radiation and heat resistant materials, higher operating temperatures are feasible.

Madhukeshwara. N, E. S. Prakash

2012-01-01

288

An investigation on the performance characteristics of solar flat plate collector with different selective surface coatings  

Energy Technology Data Exchange (ETDEWEB)

In the present work, investigations are made to study performance characteristics of solar flat plate collector with different selective surface coatings. Flat plate collector is one of the important solar energy trapping device which uses air or water as working fluid. Of the many solar collector concepts presently being developed, the relative simple flat plate solar collector has found the widest application so far. Its characteristics are known, and compared with other collector types, it is the easiest and least expensive to fabricate, install, and maintain. Moreover, it is capable of using both the diffuse and the direct beam solar radiation. For residential and commercial use, flat plate collectors can produce heat at sufficiently high temperatures to heat swimming pools, domestic hot water, and buildings; they also can operate a cooling unit, particularly if the incident sunlight is increased by the use of reflector. Temperatures up to 70 C are easily attained by flat plate collectors. With very careful engineering using special surfaces, reflectors to increase the incident radiation and heat resistant materials, higher operating temperatures are feasible.

Madhukeshwara, N. [Department of Mechanical Engineering, B.I.E.T, Davanagere, Karnataka (India); Prakash, E.S. [Department of Studies in Mechanical Engineering, U.B.D.T.C.E, Davanagere, Karnataka (India)

2012-07-01

289

Solar Thermal Systems Performances versus Flat Plate Solar Collectors Connected in Series  

Directory of Open Access Journals (Sweden)

Full Text Available This paper shows the modeling of a solar collective heating system in order to predict the system performances. Two systems are proposed: 1 the first, Solar Direct Hot Water, which is composed of flat plate collectors and thermal storage tank, 2 the second, a Solar Indirect Hot Water in which we added an external heat exchanger of constant effectiveness to the first system. The mass flow rate by a collector is fixed to 0.04 Kg?s–1 and the total number of collectors is adjusted to 60. For the first system, the maximum average water temperature within the tank in a typical day in summer and annual performances are calculated by varying the number of collectors connected in series. For the second, this paper shows the detailed analysis of water temperature within the storage and annual performances by varying the mass flow rate on the cold side of the heat exchanger and the number of collectors in series on the hot side. It is shown that the stratification within the storage is strongly influenced by mass flow rate and the connections between collectors. It is also demonstrated that the number of collectors that can be connected in series is limited. The optimization of the mass flow rate on cold side of the heat exchanger is seen to be an important factor for the energy saving.

Khaled Zelzouli

2012-12-01

290

A finite-volume model of a parabolic trough photovoltaic/thermal collector: Energetic and exergetic analyses  

International Nuclear Information System (INIS)

This paper presents a detailed finite-volume model of a concentrating photovoltaic/thermal (PVT) solar collector. The PVT solar collector consists in a parabolic trough concentrator and a linear triangular receiver. The bottom surfaces of the triangular receiver are equipped with triple-junction cells whereas the top surface is covered by an absorbing surface. The cooling fluid (water) flows inside a channel along the longitudinal direction of the PVT collector. The system was discretized along its axis and, for each slice of the discretized computational domain, mass and energy balances were considered. The model allows one to evaluate both thermodynamic and electrical parameters along the axis of the PVT collector. Then, for each slice of the computational domain, exergy balances were also considered in order to evaluate the corresponding exergy destruction rate and exergetic efficiency. Therefore, the model also calculates the magnitude of the irreversibilities inside the collector and it allows one to detect where these irreversibilities occur. A sensitivity analysis is also performed with the scope to evaluate the effect of the variation of the main design/environmental parameters on the energetic and exergetic performance of the PVT collector. -- Highlights: ? The paper investigates an innovative concentrating photovoltaic thermal solar collector. ? The collector is equipped with triple-junction photovoltaic layers. ? A local exergetic analysis is performed in order to detect sources of irreversibilities. ? Irreversibilities are mainly due to the heat transfer between sun and PVT collector.

291

In situ built-up air collector with glass cover  

DEFF Research Database (Denmark)

In the first part of the project background information was gathered describing different jointing methods and materials that can be used for glass joints. In the light hereof indoor tests with different methods of jointing between glass were carried out. From this information a test box was built with a cover of glass where the horizontal joints were made by means of different methods and materials. As a general principle a water-damming border at the horizontal glass joints was avoided. The test box was built as a solar collector with 14 different horizontal joints between the glasses. The box was placed outdoors on a 45° tilted angled south-facing plate so that the joints were exposed to real weather conditions. At regular intervals the joints were inspected. After about 3-5 months 2 possibly suitable joints were selected to form part of two prototypes,one of which is a newly developed jointing profile. The prototypes were built in the test area of Department of Buildings and Energy. One of the prototypes has the airflow behind the absorber, which is an aluminium plate painted black, whereas the other has the airflow in front of the absorber. Here the black top side of the insulation acts as an absorber. Efficiency and aair pressure drop were measured. The efficiency of the two air solar collectors was almost similar and at the same level as other corresponding air solar collectors. The air pressure drop was somewhat larger in the case of the solar collector where the air flows behind the absorber. This is due to the narrower air gap behind the absorber. Condensation has been observed in both the solar collectors, this has not been investigated more explicitly,

Kristiansen, Finn Harken; Engelmark, Jesper

1998-01-01

292

Nocturnal radiation from a solar collector  

Science.gov (United States)

As the sky temperature during the night is relatively low compared to the ambient temperature, the temperature of the absorber plate in a solar collector can be lower than the ambient temperature due to nocturnal radiation. Measurements have been made for Lennox Solar Collectors installed in a solar heating and cooling project, a same collector in Rapid City and a simple home-made collector in the laboratory. The home-made collector consists of a brass-copper plate sprayed with flat-black paint, covered with glass sheets and boxed with two inch thick styrofoam insulation. A cooling as much as 10 C in winter has been observed. It is expected to be appreciably more in summer. This suggests a potential utilization of nocturnal radiation for air conditioning. Theoretical analysis is presented.

Wang, H. F.; Chiang, C. W.

1980-11-01

293

Camera system with array of radiant energy detectors  

International Nuclear Information System (INIS)

A gamma camera has an array of photodetectors arranged to produce a current pulse in response to a flash light produced by a scintillator in response to an incident gamma ray photon. Said current pulse is passed to an integrator which produces a voltage which rises from an initial reference level, to a peak level, said peak level being representative of the charge in the current pulse. The output of the integrator is reset by a circuit to the initial reference level a predetermined time after the production of the current pulse, thereby enabling each integrator to respond to the next current pulse produced by succeeding gamma ray photons. (author)

294

Thermodynamic limits for efficiency of radiant energy conversion  

International Nuclear Information System (INIS)

Thermodynamic limits determining possible values of equilibrium radiation conversion to work in radiation exchange of a converter with a high-temperature source with low-temperature one and also in the absence of converter heat exchange with medium are considered. In the last case, maximal efficiency is determined by a relation of radiation exchange aperture, but not only by a relation of temperatures of power sources

295

Some aspects of radiant energy damage to the retina  

International Nuclear Information System (INIS)

The retinae of anaesthetised Dutch rabbits were exposed to white light of various intensities (67-235 mW/cm2 measured at 2,5 cms from the end plate of the light guide) for a period of one h. After this period the animals were killed and tissue taken for investigation by light and electron microscopy. The higher intensities produced marked disruption of the visual cell outer and inner segments as well es a variety of morphological changes in the pigment epithelium. The highest intensity produced severe disruption of the visual cells and pigment epithelium in addition to a general disruption of the other retinal layers. Accompanying the retinal damage there was an inflammatory response in the choroid of the experimental eyes and surprisingly, at some intensities, a similar inflammatory response in the choroid of the control eye. (orig.)

296

Methods to Reduce the Risk to Wind Action of the Fixing Systems of Sollar Collectors  

OpenAIRE

The interest in the non-conventional energy resources, a consequence of the severe restrictions imposed towards pollution of any kind, arises again the interest in using solar collectors. Implanting them on the terraces of new or existent home residencies, or any kind of other buildings, means to solve a sum of engineering problems, among them being also the stages of safely designing the plane panels for collectors and the sustaining skeleton, made in steel as well as the fixing systems adop...

Elena Axinte; Elena-Carmen Teleman; Victoria-Elena Ro?ca; Georgeta Vasie?

2010-01-01

297

Modeling Spatio-Temporal Dynamics of Optimum Tilt Angles for Solar Collectors in Turkey  

OpenAIRE

Quantifying spatial and temporal variations in optimal tilt angle of a solar collector relative to a horizontal position assists in maximizing its performance for energy collection depending on changes in time and space. In this study, optimal tilt angles were quantified for solar collectors based on the monthly global and diffuse solar radiation on a horizontal surface across Turkey. The dataset of monthly average daily global solar radiation was obtained from 158 places, and monthly diffuse...

Recep Kulcu; Fatih Evrendilek; Can Ertekin

2008-01-01

298

Field Experiments of PV-Thermal Collectors for Residential Application in Bangkok  

OpenAIRE

This study presents experimental results on Photovoltaic-thermal (PVT) solar systems, the commercial photovoltaic (PV) panels used as solar absorbers in PVT collectors, which are amorphous and multi-crystalline silicon. Testing was done with outdoor experiments in the climate of Bangkok corresponding to energy consumption behavior of medium size Thai families. The experimental results show that the thermal recovery of amorphous silicon PVT collector is almost the same as that of multi-crystal...

Atsushi Akisawa; Yuki Ueda; Pongpith Tuenpusa; Thipjak Nualboonrueng

2012-01-01

299

Experimental and theoretical development of a thermal design tool for radiant domestic stoves. Paper no. IGEC-1-003  

International Nuclear Information System (INIS)

A steady-state space radiant heat model and a stove combustion model are developed to simulate the heat exchanges between various surfaces in the room and the stove and stack surfaces, assuming stiochiometric combustion inside the stove and the exhaust gases flow out through the stack by natural convection. The space heat model calculates the fuel consumption, the stove, stack temperatures, and the mass flow rate of exhaust gases, and provides an opportunity to study energy efficiency of stove, while satisfying the constraints of thermal comfort. Fanger (1982) model and a radiation exchange model between various surfaces of the space, the thermal building energy balance, and stove combustion process is applied to determine the mean radiant temperature (MRT) and the extent of thermal comfort as determined by predicted mean vote (PMV). The overall model is validated by performing experiments in a room placed inside controlled outdoor environment. The room is heated using a common domestic stove for rural areas of Lebanon. The measured MRT, the average room temperature, the wall surfaces temperatures agreed within ±7% of values predicted by the numerical model. A parametric study using the developed models reveals that the values of MRT and PMV depend strongly on the position of the radiant stove heater and stack with respect to the cold window and the occupant location. It is shown that it is possible to save up to 15% in fuel consumption of the stove by changing the sonsumption of the stove by changing the stove position in the room with respect to the window and to the person, while maintaining the same level of comfort. (author)

300

Comparative study of solar cooling systems with building-integrated solar collectors for use in sub-tropical regions like Hong Kong  

International Nuclear Information System (INIS)

Highlights: ? Performance of building-integrated solar collectors analyzed. ? Comparisons made with solar collectors installed on roof. ? Use of building-integrated solar collectors increased the total primary consumption. ? Reduction in the building load could not compensate drop in solar collector output. ? Building-integrated solar collectors only used when roof space insufficient. -- Abstract: The performance of solar cooling systems with building-integrated (BI) solar collectors was simulated and the results compared with those having the solar collectors installed conventionally on the roof based on the weather data in Hong Kong. Two types of solar collectors and the corresponding cooling systems, namely the flat-plate collectors for absorption refrigeration and the PV panels for DC-driven vapour compression refrigeration, were used in the analysis. It was found that in both cases, the adoption of BI solar collectors resulted in a lower solar fraction (SF) and consequently a higher primary energy consumption even though the zone loads were reduced. The reduction in SF was more pronounced in the peak load season when the solar radiation was nearly parallel to the solar collector surfaces during the daytimes, especially for those facing the south direction. Indeed, there were no outputs from the BI flat-plate collectors facing the south direction between May and July. The more severe deterioration in the system performance with the BI flat-plate type collectors made them technically infeasible in terms of the energy-saving potential. It was concluded that the use of BI solar collectors in solar cooling systems should be restricted only to situations where the availability of the roof was limited or insufficient when applied in sub-tropical regions like Hong Kong.

301

Diboride and zirconium carbide oxidation under radiant heating  

International Nuclear Information System (INIS)

Peculiarities of oxide layers formation on carbide and zirconium diboride at thermal (below 1200 deg C) and radiant (below 3000 deg C) heating are comparatively studied. The X-ray phase and petrographic analyses are used to establish that two oxide phases ZrO2 of cubic and monoclinic structure are formed on the ZrC surface below 1400 deg C, over 1400 deg C only monoclinic ZrO2 is formed, which is characterized by high adhesion with the base at a temperature of 2700 deg C. Monoclinic modification ZrO2 as well as B2O3 is the main oxide phase during oxidation of ZrB2. The scale, which is most stable and strictly coalesced with the base is formed on the surface of ZrB2 specimens at a temperature over 2800 deg C

302

Radiant-and-plasma technology for coal processing  

Directory of Open Access Journals (Sweden)

Full Text Available Radiant-and-plasma technology for coal processing is presented in the article. Thermodynamic computation and experiments on plasma processing of bituminous coal preliminary electron-beam activated were fulfilled in comparison with plasma processing of the coal. Positive influence of the preliminary electron-beam activation of coal on synthesis gas yield was found. Experiments were carried out in the plasma gasifier of 100 kW power. As a result of the measurements of material and heat balance of the process gave the following integral indicators: weight-average temperature of 2200-2300 K, and carbon gasification degree of 82,4-83,2%. Synthesis gas yield at thermochemical preparation of raw coal dust for burning was 24,5% and in the case of electron-beam activation of coal synthesis gas yield reached 36,4%, which is 48% higher.

Vladimir Messerle

2012-12-01

303

New Radiant Areas of the Perseid Meteor Shower  

Science.gov (United States)

More than 100 Perseid meteors were recorded by using TV techniqes at four stations on August 11/12 and 12/13, 1993. The lenses of MINOLTA f = 135mm F2 (at two sites), CANNON f = 85mm F1.2, and NIKON f = 85mm F1.4 were used. A PC with a frame memory board was utilized in order to sample the video with a spatial resolution of 512 times 512 pixels and with 8 bit tone levels. (i.e.256 gray levels). The positional traceability was within plus or minus 1 pixel at the worst. Orbits of meteors were determined with an accuracy within 60 seconds of arc with regard to the reference stars. New radiant areas of the Perseid meteor shower observed in 1993 will be reported in this paper.

Yoshida, T.; Suzuki, S.; Suzuki, K.; Akebo, T.

304

Research on a Radiant Source for Infrared Image Calibration  

Energy Technology Data Exchange (ETDEWEB)

The theory, concepts and applications of blackbody cavities were introduced in this paper. Characteristics of a new kind blackbody cavity with large aperture which can be used as standard radiant source in infrared imaging system were discussed. The bottom of blackbody cavities was grooved with homocentric cycles in order to increase its intrinsic emissivity. The effective emissivity {epsilon}a(r) of the bottom of the cavity were analyzed and calculated by combing the integrated equation method and the Monte Carlo method. For large number of Monte Carlo simulation, rejection Sample method was used to simulate the Monte Carlo probability model constructed in order to reduce the calculating time. The cavity characteristics have been further proved via testing the consistency and stability of the temperature field. The characteristics of this kind of heat pipe blackbody cavities with large aperture have been authenticated.

Zhang, H [School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin, 150001 (China); Dai, J M [School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin, 150001 (China); Sun, X G [School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin, 150001 (China)

2006-10-15

305

Numerical modelling of a parabolic trough solar collector  

OpenAIRE

Concentrated Solar Power (CSP) technologies are gaining increasing interest in electricity generation due to the good potential for scaling up renewable energy at the utility level. Parabolic trough solar collector (PTC) is economically the most proven and advanced of the various CSP technologies. The modelling of these devices is a key aspect in the improvement of their design and performances which can represent a considerable increase of the overall efficiency of solar power plants. In the...

Hachicha, Ahmed Amine

2013-01-01

306

Numerical Modelling of Non-similar Mixed Convection Heat and Species Transfer along an Inclined Solar Energy Collector Surface with Cross Diffusion Effects  

Directory of Open Access Journals (Sweden)

Full Text Available An analysis is performed to study thermo-diffusion and diffusion-thermo effects on mixed convection heat and mass transfer boundary layer flow along an inclined (solar collector plate. The resulting governing equations are transformed and then solved numerically using the local nonsimilarity method and Runge-Kutta shooting quadrature. A parametric study illustrating the influence of thermal buoyancy parameter (ζ, Prandtl number (Pr, Schmidt number (Sc, Soret number (Sr, Dufour number (Du and concentration-to- thermal-buoyancy ratio parameter, N, on the fluid velocity, temperature and concentration profiles as well as on local skin-friction, Nusselt and Sherwood numbers is conducted. For positive inclination angle of the plate (γ = 70 degrees, flow velocity (f' is strongly increased i.e. accelerated, with thermal buoyancy force parameter (&950, in particular closer to the plate surface; further into the boundary layer, ζ has a much reduced effect. Conversely temperature (θ and concentration (ψ is decreased with increasing thermal buoyancy parameter, ζ. For negative plate inclination, the flow is accelerated whereas for positive inclination it is decelerated i.e. velocity is reduced. Conversely with negative plate inclination both the temperature and concentration in the boundary layer is reduced with the opposite apparent for positive inclination. Increasing Prandtl number strongly reduces temperature in the regime whereas an increase in Schmidt number boosts temperatures with temperature overshoots near the plate surface for Sc = 3 and 5 (i.e. for Sc > 1. Concentration is reduced continuously throughout the boundary layer, however, with increasing Schmidt number. A positive increase in concentration-to-thermal-buoyancy ratio parameter, N, significantly accelerates the flow in the domain, whereas negative N causes a deceleration. A velocity overshoot is also identified for N = 20, at intermediate distance from the plate surface. Negative N (thermal and concentration buoyancy forces oppose each other induces a slight increase in both fluid temperature and concentration, with the reverse observed for positive N (thermal and concentration buoyancy forces assisting each other. Increasing Dufour number respectively causes a rise in temperature and a decrease in concentration, whereas an increase in Soret number cools the fluid i.e. reduces temperature and enhances concentration values. In the absence of Soret and Dufour effects, positive N causes a monotonic increase in local Nusselt number, NuxRex-1/2 with ζ Cos γ, for N = -1 the local Nusselt number remains constant for all values of parameter, ζ Cos γ. Local Sherwood number, ShxRex-1/2 is boosted considerably with higher Schmidt numbers and also with positive N values. The computations in the absence of Soret and Dufour effects correlate accurately with the earlier study by Chen et al. (1980.

Osman Anwar Bég

2011-09-01

307

Human response to local convective and radiant cooling in a warm environment.  

DEFF Research Database (Denmark)

The response of 24 human subjects to local convective cooling, radiant cooling, and combined radiant and convective cooling was studied at 28°C and 50% relative humidity. The local cooling devices used were (1) a tabletop cooling fan, (2) personalized ventilation providing a stream of clean air, (3) radiant panels below and above the desk in front of the desk occupant, and (4) the same two radiant panels but with small fans blowing room air toward the upper panel to be cooled and redirected toward the person. A reference condition without cooling was also tested. The cooling devices significantly (p<0.05) improved subjects’ thermal comfort compared to the condition without cooling. The acceptability of the thermal environment was similar for all cooling devices. The acceptability of air movement and perceived air quality increased when local cooling methods were used. The best results were achieved with personalized ventilation or the tabletop fan. Only minimal improvement in perceived air quality was reported when the radiant panel was used alone, indicating that in a warm environment, local convective cooling is superior to local radiant cooling as a means of improving perceived air quality. The intensity of the reported sick building syndrome symptoms increased during the exposure time, with or without cooling devices in operation. Air movement had very little effect on sick building syndrome symptoms, but they increased when the pollution level was high. The lowest prevalence of symptoms was reported with personalized ventilation and with the radiant panel with attached fans, which also caused subjects to report less fatigue. Sick building syndrome symptoms increased most when the tabletop fan, generating movement of polluted room air, was in operation. The temperature of the inhaled air rather than any local cooling of the head was associated with sick building syndrome symptoms, although this needs further study. The most preferred cooling method was personalized ventilation for six subjects, fan for eight subjects, and radiant panel (or radiant panel + fans) for nine subjects.

Melikov, Arsen Krikor; Krejcirikova, Barbora

2013-01-01

308

Thermal Efficiency of Double Pass Solar Collector with Longitudinal Fins Absorbers  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: One of the most important components of a solar energy system is the solar collector. The performances of double-pass solar collector with longitudinal fins absorbers are analyzed. Approach: The study involves a theoretical study to investigate the effect of mass flow rate, number and height of fins on efficiency, which involves steady-state energy balance equations on the longitudinal fins absorber of solar collectors. The theoretical solution procedure of the energy equations uses a matrix inversion method and making some algebraic rearrangements. Results: The collector efficiency increases as the number and height of fins increases. For a mass flow rate 0.02- 0.1kg/s, the double-pass solar collectors are efficiency about 36-73% in upper fins (type I, 37-75% in lower fins (type II and 46-74% in upper and lower fins (type III. Conclusion: The efficiency of the collector is strongly dependent on the flow rate, efficiency increase is about 35%.

Ahmad Fudholi

2011-01-01

309

Energy detection method and apparatus  

International Nuclear Information System (INIS)

A method is described of detecting neutrinos comprising the steps of irradiating a material with the neutrinos to cause coherent stimulated emission of radiant energy fields in the material in response to the material being irradiated by the neutrinos, and detecting the coherent radiant energy fields

310

Mobile Collector for Field Trips  

Directory of Open Access Journals (Sweden)

Full Text Available Current e-Learning is based on learning management systems that provide certain standard services - course authoring and delivery, tutoring, administration and collaboration facilities. Rapid development of mobile technologies opens a new area of m-Learning to enhance the current educational opportunities. Field trips are a relevant part of the curriculum, but for various reasons it is often difficult to organize them. The aim of the RAFT project is development of a system that would enable virtual field trips. One mobile learning application prototype created in this project, called Mobile Collector, enables data gathering and annotation in the field, together with real time collaboration. The application supports learner-centred education in real world context.

Lucia Terrenghi

2004-04-01

311

The CERN antiproton collector ring  

International Nuclear Information System (INIS)

This paper reports on the improvement of the CERN antiproton source that relies on a new large acceptance ring, the antiproton collector, which acts as a buffer between the production target and the accumulator. The lattice is made of strong focusing FODO cells; long zero dispersion straight sections result from the bending magnets distribution around the ring; chromatic properties and large amplitude oscillations are controlled by sextupole fields. The antiprotons are subjected to rf debunching followed by stochastic cooling of the longitudinal and transverse phase spaces. At the end of the process, the beam emittances are compatible with the accumulation of requirements. The machine acceptance, the beam momentum spread after debunching and the phase space compression after stochastic cooling are reported and discussed

312

Performance Evaluation of a Nanofluid (CuO-H2O) Based Low Flux Solar Collector  

OpenAIRE

As the fossil fuels are depleting continuously, we know that solar energy harvesting is a significant potential area for new research dimensions. Sun provides us about 1.9 x 108 TWh/yr on the land, of which 1.3 x 105 TWh]/yr energy is used. In order to make much use of solar energy on the earth, solar energy harvesting into more usable form (e.g. heat or electricity) by using solar energy collectors is important aspect. A solar collector [1] is a device whi...

Lal Kundan, Prashant Sharma

2013-01-01

313

Theoretical and experimental study of sheet and tubes hybrid PVT collector  

International Nuclear Information System (INIS)

Highlights: • A new design of hybrid collectors was modeled and simulated. • Sheet and tubes absorber is user to form the absorber. • The used absorber satisfying simplicity and cost constraints. • A comparison with other existing configurations is performed. • Experimental validation of the mathematical model is detailed. - Abstract: Electrical performance of the hybrid photovoltaic thermal (PVT) collector may improved at increased intensity of solar radiation if the system is set to extract heat from solar cells, which is cooled at the same time. The objective of this work is to study theoretically and experimentally a new configuration of the PVT system which extracts heat from the photovoltaic module. This configuration is tube and sheet integrated into a prototype and tested at the unit of applied research in renewable energy Ghardaïa in the south of Algeria. The advantages of this hybrid collector are better heat absorption and lower production cost compared to other configurations of hybrids collectors

314

A mobile apparatus for solar collector testing  

Science.gov (United States)

The design, construction, and operation of a mobile apparatus for solar collector testing (MASCOT) is described. The MASCOT is a self-contained test unit costing about $10,000 whose only external requirement for operation is electrical power and which is capable of testing two water-cooled flat-plate solar collectors simultaneously. The MASCOT is small enough and light enough to be transported to any geographical site for outdoor tests at the location of collector usage. It has been used in both indoor solar simulator tests and outdoor tests.

Hotchkiss, G. B.; Simon, F. F.; Burmeister, L. C.

1979-01-01

315

EFFICIENCY AND LIFETIME OF SOLAR COLLECTORS FOR SOLAR HEATING PLANTS  

DEFF Research Database (Denmark)

The 12.5 m² flat plate solar collector HT, today marketed by Arcon Solvarme A/S, has been used in solar heating plants in Scandinavia since 1983. The collector is designed to operate in a temperature interval between 40°C and 90°C. The efficiency of the collector has been strongly improved since it was introduced on the market. The paper will present the increase of the efficiency of the collector due to technical improvements since 1983. Further, measurements from the spring of 2009 of the efficiency of two HT collectors, which have been in operation in the solar heating plant Ottrupgaard, Skørping, Denmark since 1994 with a constant high flow rate and in the solar heating plant Marstal, Denmark since 1996 with a variable flow rate, will be presented. The efficiencies will be compared to the efficiencies of the collectors when they were first installed in the solar heating plants. The measurements are supplied with inspections of the collectors inclusive investigations of possible corrosion of the copper pipes of the absorbers of the collectors. It is shown that from 2002 to 2007 the thermal performance of solar collector has been increased by 29%, 39%, 55% and 80% for a mean solar collector fluid temperature of 40?C, 60°C, 80°C and 100°C respectively due to improvement of the collector design. The test of the two collectors shows that due to aging the Ottrupgård collector has a yearly thermal performance which is 4% lower than for the collector tested in 1991 for a solar collector fluid temperature of 45°C, while the Marstal collector has a yearly thermal performance which is 1% lower than the collector tested in 1991. With an increase of the solar collector fluid temperature to 60°C, the yearly thermal performance of the Ottrupgård collector and the Marstal collector is respectively 11% and 10% lower than the collector tested in 1991.

316

Parametric sensitivity studies on the performance of a flat plate solar collector in transient behavior  

International Nuclear Information System (INIS)

Highlights: • Parametric studies of a flat plate solar collector is developed. • The model predicts the temperature profile of all the components of the collector and of the working fluid. • A simulation program was constructed to study the effect parameters. • The optimal performance and design of solar collector system was carried out. - Abstract: In this paper, a numerical investigation of flat plate solar collectors is developed to determine the optimal performance and design parameters of these solar to thermal energy conversion systems. The collector is used to supply hot water. It consists of three main components, namely a transparent cover, an absorber and a transfer fluid. A transient simulation method has been developed to characterize the dynamic behavior. The model was established regarding the energy balance analysis. A set of equations representing the model was simultaneously solved. The results are used to investigate the effect of various parameters on the performance of the collector such as outlet water temperature and overall heat loss coefficient. The overall methodology has been developed on environmental data which are characteristic of the city of Gabes in Tunisia

317

Performance analysis of a hybrid photovoltaic/thermal (PV/T) collector with integrated CPC troughs  

Energy Technology Data Exchange (ETDEWEB)

In the present investigation a theoretical analysis has been presented for the modelling of thermal and electrical processes of a hybrid PV/T air heating collector coupled with a compound parabolic concentrator (CPC). In this design, several CPC troughs are combined in a single PV/T collector panel. The absorber of the hybrid PV/T collector under investigation consists of an array of solar cells for generation of electricity, while collector fluid circulating past the absorber provides useful thermal energy as in a conventional flat plate collector. In the analysis, it is assumed that solar cell efficiency can be represented by a linear decreasing function of its temperature. Energy balance equations have been developed for the various components of the system. Based on the developed analysis, both thermal and electrical performance of the system as a function of system design parameters are presented and discussed. Results have been presented to compare the performance of hybrid PV/T collector coupled with and without CPC. (Author)

Garg, H.P.; Adhikari, R.S. [Indian Inst. of Technology, Centre for Energy Studies, New Delhi (India)

1999-07-01

318

New generation of hybrid solar PV/T collectors  

Energy Technology Data Exchange (ETDEWEB)

This final report for the Swiss Federal Office of Energy (SFOE) presents the results of a study made on the suitability of commercially available panels using amorphous silicon (a-Si) technology for use in hybrid photovoltaic-thermal collectors. A previously made feasibility study is quoted that showed that the competitiveness of hybrid collectors depends on the technical requirements placed on the integrated photovoltaic modules. The detail results of tests made on unencapsulated samples of a-Si modules based on various different substrates are presented. These include assessment of absorption factors on the basis of spectrometric and calorimetric measurements, testing of the thermal stability of the a-Si cells and emissivity measurements made on the top-cover materials used in the panels. The report is concluded with recommendations for the development of new encapsulation materials with low emissivity and improved durability at high temperatures.

NONE

2000-07-01

319

Lightweight diaphragm mirror module system for solar collectors  

Science.gov (United States)

A mirror module system is provided for accurately focusing solar radiation on a point or a line as defined by an array of solar collectors. Each mirror module includes a flexible membrane stretched over a frame in a manner similar to that of a drum or a trampoline and further includes a silvered glass or plastic mirror for forming an optical reflecting surface. The configuration of the optical reflecting surface is variably adjustable to provide for the accurate focusing of the solar energy on a given collector array, e.g., a point or a linear array arrangement. The flexible mirror-membrane combination is lightweight to facilitate installation and reduce system cost yet structurally strong enough to provide for the precise focusing of the incident solar radiation in a semi-rigid reflector system in which unwanted reflector displacement is minimized.

Butler, Barry L. (Golden, CO)

1985-01-01

320

Longevity characteristics of flat solar water-heating collectors in hot-water-supply systems. Part 1. Procedure for calculating collector thermal output  

International Nuclear Information System (INIS)

A procedure for calculating longevity indices (daily and monthly variations and, hence, annual thermal output) of flat solar water-heating collectors, amount of conditional fuel saved per year by using solar energy, and cost of solar fuel and thermal energy generated in hot-water-supply systems is described. (authors)

321

Role of collector alternating charged patches on transport of Cryptosporidium parvum oocyst in a patchwise charged heterogeneous micromodel  

Energy Technology Data Exchange (ETDEWEB)

The role of collector surface charge heterogeneity on transport of Cryptosporidium parvum oocyst and carboxylate microsphere in 2-dimensional micromodels was studied. The cylindrical silica collectors within the micromodels were coated with 0, 10, 20, 50 and 100% Fe2O3 patches. The experimental values of average single collector removal efficiencies (?) of the Fe2O3 patches and on the entire collectors were determined. In the presence of significant (>3500 kT) Derjaguin–Landau–Verwey–Overbeek (DLVO) energy barrier between the microspheres and the silica collectors at pH 5.8 and 8.1, the values of ? determined for Fe2O3 patches were significantly less (p < 0.05, t-test) than that obtained for collectors coated entirely with Fe2O3. However, ? on Fe2O3 patches for microspheres at pH 4.4 and for oocysts at pH 5.8 and 8.1, where the DLVO energy barrier was relatively small (ca. 200-360 kT), were significantly greater (p < 0.05, t-test) than that on the collectors coated entirely with Fe2O3. The dependence of ? determined for Fe2O3 patches on the DLVO energy barrier indicated the importance of periodic favorable and unfavorable electrostatic interactions between colloids and collectors with alternating Fe2O3 and silica patches. Differences between experimentally determined ? and that predicted by a patchwise geochemical heterogeneous model was observed, but can be explained by the model’s lack of consideration for the spatial distribution of charge heterogeneity on the collector surface and colloid migration on patchwise heterogeneous collectors.

Liu, Yuanyuan; Zhang, Changyong; Hu, Dehong; Kuhlenschmidt, Mark S.; Kuhlenschmidt, Theresa B.; Mylon, Steven E.; Kong, Rong; Bhargava, Rohit; Nguyen, Thanh H.

2013-02-04

322

Solar hybrid cooling system for high-tech offices in subtropical climate - Radiant cooling by absorption refrigeration and desiccant dehumidification  

Energy Technology Data Exchange (ETDEWEB)

Highlights: {yields} A solar hybrid cooling system is proposed for high-tech offices in subtropical climate. {yields} An integration of radiant cooling, absorption refrigeration and desiccant dehumidification. {yields} Year-round cooling and energy performances were evaluated through dynamic simulation. {yields} Its annual primary energy consumption was lower than conventional system up to 36.5%. {yields} The passive chilled beams were more energy-efficient than the active chilled beams. - Abstract: A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual primary energy consumption of the solar hybrid cooling system was lower than that of the conventional vapour compression refrigeration system up to 36.5%. Between the two options of chilled ceilings, the passive chilled beams were more energy-efficient to work with the solar hybrid cooling system in the hot and humid climate. Harnessing solar energy for driving air-conditioning would help in reducing the carbon emission, hence alleviating the climate change.

Fong, K.F., E-mail: bssquare@cityu.edu.hk [Building Energy and Environmental Technology Research Unit, School of Energy and Environment and Division of Building Science and Technology, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong (China); Chow, T.T.; Lee, C.K.; Lin, Z.; Chan, L.S. [Building Energy and Environmental Technology Research Unit, School of Energy and Environment and Division of Building Science and Technology, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong (China)

2011-08-15

323

Solar hybrid cooling system for high-tech offices in subtropical climate - Radiant cooling by absorption refrigeration and desiccant dehumidification  

International Nuclear Information System (INIS)

Highlights: ? A solar hybrid cooling system is proposed for high-tech offices in subtropical climate. ? An integration of radiant cooling, absorption refrigeration and desiccant dehumidification. ? Year-round cooling and energy performances were evaluated through dynamic simulation. ? Its annual primary energy consumption was lower than conventional system up to 36.5%. ? The passive chilled beams were more energy-efficient than the active chilled beams. - Abstract: A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal d with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual primary energy consumption of the solar hybrid cooling system was lower than that of the conventional vapour compression refrigeration system up to 36.5%. Between the two options of chilled ceilings, the passive chilled beams were more energy-efficient to work with the solar hybrid cooling system in the hot and humid climate. Harnessing solar energy for driving air-conditioning would help in reducing the carbon emission, hence alleviating the climate change.

324

CISBAT 2007 - Solar collectors (heat and electricity)  

International Nuclear Information System (INIS)

This is the third part of the proceedings of the 2007 CISBAT conference on Renewables in a changing climate, held in Lausanne, Switzerland. On the subject of Building and urban integration of renewables the following oral contributions are summarised: 'Facade integration of solar thermal collectors: present and future', 'Long term experiences with a versatile PV in roof system', 'Development of a design and performance prediction tool for the ground source heat pump and underground thermal storage system', 'Hygrothermal performance of earth-to-air heat exchanger: long-term data evaluation and short-term simulation' as well as 'The real cost of heating your home: a comparative assessment of home energy systems with external costs'. Poster-sessions on the subject include 'Central solar heating plants with seasonal heat storage', 'Analysis of forced convection for evaporative air flow and heat transfer in PV cooling channels', 'Renewable energy technology in Mali: constraints and options for a sustainable development', 'Effect of duct width in ducted photovoltaic facades', 'Design and actual measurement of a ground source heat pump system using steel foundation piles as ground heat exchangers', 'Development of an integrated water-water heat pump unit for low energy house and its application', 'PV effect in multilayer cells and blending of fullerene/poly (3-hexylthiophene) and phthalocyanine having NIR charge transfer absorption band', 'CdTe photovoltaic systems - an alteand', 'CdTe photovoltaic systems - an alternative energetic', 'Integration of renewable energy sources in a town, examples in Grenoble', 'A prospective analysis method for the conception of solar integration solutions in buildings' and 'Energy and aesthetic improvements for building integration of cost effective solar energy systems'. Further groups of presentations at the conference are reported on in separate database records. An index of authors completes the proceedings

325

Maximization od solar energy per square meter by means of PVT (Photovoltaic thermal hybrid solar collectors). Sustainable heating system for Rijksgebouwendienst Zoetermeer, Netherlands; Maximalisering zonne-energie per vierkante meter met PVT. Duurzaam verwarmingssysteem Rijksgebouwendienst Zoetermeer  

Energy Technology Data Exchange (ETDEWEB)

An office building of the Dutch Government Buildings Agency (RGD) in Zoetermeer, Netherlands, is monitored to determine the feasibility of PVT (Photovoltaic thermal hybrid solar collectors) panels. The PVT system is connected to the hot tap water system. The aim is to be able to calculate reliable yields and to test the applicability for the Netherlands [Dutch] Een kantoorgebouw van de Rijksgebouwendienst in Zoetermeer is gemonitord om de haalbaarheid van PVT-panelen (fotovoltaische thermische hybride zonnecollectoren) te bepalen. Het PVT-systeem is aangesloten op het warmtapwaterysteem. Het doel is betrouwbare opbrengsten te kunnen berekenen en de toepasbaarheid voor Nederland te testen.

Van Helden, W. [Renewable Heat, Schagen (Netherlands); Roossien, B. [EnergyGO, Den Helder (Netherlands); Mimpen, J. [Rijksgebouwendienst, Zoetermeer (Netherlands)

2013-02-15

326

Flight performance of radiant coolers onboard FengYun-2 satellites  

Science.gov (United States)

The IR detectors of optical instruments onboard FengYun-2 (FY-2) meteorological satellites are cooled by passive radiant coolers (RC). The operation principles, characteristics and flight performance of the radiant coolers installed on four FengYun-2 satellites (FY-2C/D/E/F) are presented. The orbiting data from the four satellites (FY-2C/D/E/F) are tabulated and compared. It is concluded that the radiant coolers (FY-2E/F) can operate stably at 93 K in the sunshine and have a long service lifetime. The major technologies of FY-2 radiant coolers are mainly discussed in terms of thin-walled structure design and optical coating of the sun shield. The problem of contamination control in orbit is solved.

Zhang, Yulin; Zhou, Xiyan

2014-11-01

327

Experimental study on the globe thermometer behaviour in conditions of asymmetry of the radiant temperature  

International Nuclear Information System (INIS)

Heating and cooling systems based on the use of hot or cold floors or ceilings meet increasing favour. In such systems, moreover, radiant temperature gains a far greater importance than in traditional systems; and therefore the importance of measurement and control techniques grow; but at the same time, in presence of these systems, unavoidably the radiant field tends to become asymmetrical. In this work a theoretical study and an experimental check on the most common radiant temperature measurement tool, the globe thermometer, when used in conditions of asymmetrical radiant temperature, are described. The results point out the necessity of a more complete definition of the features of the globe thermometers designed to operate in non-symmetric radiative fields, especially with reference to covering material and thickness, to temperature sensor position and to radiative properties of the inner surface.

328

Automatic drawing and cad actualiztion in processing data of radiant sampling in physics prospect  

International Nuclear Information System (INIS)

In this paper discussed a method of processing radiant sampling data with computer. By this method can get explain the curve of radiant sampling data, and we can combine mineral masses and analyses and calculate them, then record the result on Notebook. There are many merites of this method: easy to learn, simple to use, high efficient. It adapts to all sorts of mines. (authors)

329

Automatic drawing and CAD actualization in processing data of radiant sampling in physics prospect  

International Nuclear Information System (INIS)

In this paper discussed a method of processing radiant sampling data with computer. By this method can get expain the curve of radiant sampling data, and we can combine mineral masses and analyse and calculate them, then record the result on Notebook. There are many merites of this method: easy to learn, simple to use, high efficient. It adapts to all sorts of mines. (authors)

330

Potential collector surface materials for divertors  

International Nuclear Information System (INIS)

Twelve refractory materials have been investigated to assess their suitability for use as collector target materials for divertors. The steady state limiting heat flux to avoid melting of the collector material has been calculated as a function of thickness using a simple one-dimensional thermal-hydraulics model. Similarly, the limiting heat flux to avoid melting following a plasma disruption has been calculated as a function of collector surface temperature just prior to the disruption event. Finally, the resistance of each collector material to thermal shock was estimated. The calculations indicate diamond, graphite and tungsten as favourable materials, BN, A1N, TiN, V2C and beryllium as unsuitable and BeO, SiC, TiC and TiB2 as exhibiting combinations of favourable and unfavourable properties. (orig.)

331

Tilt assembly for tracking solar collector assembly  

Science.gov (United States)

A tilt assembly is used with a solar collector assembly of the type comprising a frame, supporting a solar collector, for movement about a tilt axis by pivoting a drive element between first and second orientations. The tilt assembly comprises a drive element coupler connected to the drive element and a driver, the driver comprising a drive frame, a drive arm and a drive arm driver. The drive arm is mounted to the drive frame for pivotal movement about a drive arm axis. Movement on the drive arm mimics movement of the drive element. Drive element couplers can extend in opposite directions from the outer portion of the drive arm, whereby the assembly can be used between adjacent solar collector assemblies in a row of solar collector assemblies.

Almy, Charles; Peurach, John; Sandler, Reuben

2012-01-24

332

Performance of a solar-thermal collector  

Science.gov (United States)

Possible means of achieving the technology required for field application of solar thermal power systems are discussed. Simplifications in construction techniques as well as in measurement techniques for parabolic trough collectors are described. Actual measurement data is also given.

Higa, W. H.

1975-01-01

333

Collectors instead of coke; Kollektoren statt Koks  

Energy Technology Data Exchange (ETDEWEB)

At Gelsenkirchen, the former coking capital of Germany, Vaillant recently commissioned a new solar collector factory, which is one of the biggest in Europe and also has the highest degree of automation. (orig.)

Augsten, Eva

2009-01-02

334

Analysis of directional radiative behavior and heating efficiency for a gas-fired radiant burner  

International Nuclear Information System (INIS)

For the purpose of energy conservation and uniform heating of object surface, a gas-fired porous radiant burner with a bundle of reflecting tubes is developed. A physical model is developed to simulate the directional radiative behavior of this heating device, in which the Monte Carlo method based on the concept of radiation distribution factor is used to compute the directional radiative behavior. The effects of relating parameters on the directional behavior of radiative heating and the heating efficiency are analyzed. With the increase of the length-to-radius ratio of tube, the radiation heating efficiency decreases, but the radiation energy incident on the object surface is more collimated. The radiation heating efficiency increases with the specular reflectivity. With the increase in length of tube segment with specular reflective surface, the radiation heating efficiency increases, but the extent of concentration and collimation of radiative energy decreases. For real design of the heating device, some trade-offs are needed to balance the radiation heating efficiency and the uniformity of radiative heating of object surface

335

Validation of a dynamic model for unglazed collectors including condensation. Application for standardized testing and simulation in TRNSYS and IDA  

DEFF Research Database (Denmark)

An improved unglazed collector model has been validated for use in TRNSYS and IDA and also for future extension of the EN12975 collector test standard. The basic model is the same as used in the EN12975 test standard in the quasi dynamic performance test method (QDT). In this case with the addition of a condensation term that can handle the operation of unglazed collectors below the dew point of the air. This is very desirable for simulation of recharging of ground source energy systems and direct operation of unglazed collectors together with a heat pump. The basic idea is to have a direct connection between collector testing and system simulation by using the same dynamic model and parameters during testing and simulation. The model together with the parameters will be validated in each test in this way. This work describes the method applied to an unglazed collector operating partly below the dew point under real dynamic weather conditions, for a long period during the autumn 2010. The validation results also show that the model can handle operation of such a collector during the night. This is a common mode of operation for this collector type in a real system.

Perers, Bengt; Kovacs, Peter

2011-01-01

336

Foldable Frame Supporting Electromagnetic Radiation Collectors  

DEFF Research Database (Denmark)

The present invention relates to flexible frames supporting electromagnetic radiation collectors, such as antennas, antenna reflectors, deflectors or solar collectors, for celestial or terrestrial applications, which can be folded to be stored and/or transported. The method for stowing deforms the flexible frame into a stressed configuration. Once released from the stressed configuration the flexible frame restores its initial configuration without any external intervention.

Kristensen, Anders Schmidt VBN,

337

Local Reasoning about a Copying Garbage Collector  

DEFF Research Database (Denmark)

We present a programming language, model, and logic appropriate for implementing and reasoning about a memory management system. We state semantically what is meant by correctness of a copying garbage collector, and employ a variant of the novel separation logics to formally specify partial correctness of Cheney’s copying garbage collector in our program logic. Finally, we prove that our implementation of Cheney’s algorithm meets its specification using the logic we have given and auxiliary variables. Udgivelsesdato: 2008

Torp-Smith, Noah; Birkedal, Lars

2008-01-01

338

Heat transfer in a low latitude flat-plate solar collector  

Directory of Open Access Journals (Sweden)

Full Text Available Study of rate of heat transfer in a flat-plate solar collector is the main subject of this paper. Measurements of collector and working fluid temperatures were carried out for one year covering the harmattan and rainy seasons in Port Harcourt, Nigeria, which is situated at the latitude of 4.858oN and longitude of 8.372oE. Energy balance equations for heat exchanger were employed to develop a mathematical model which relates the working fluid temperature with the vital collector geometric and physical design parameters. The exit fluid temperature was used to compute the rate of heat transfer to the working fluid and the efficiency of the transfer. The optimum fluid temperatures obtained for the harmattan, rainy and yearly (or combined seasons were: 317.4, 314.9 and 316.2 [K], respectively. The corresponding insolation utilized were: 83.23, 76.61 and 79.92 [W/m2], respectively, with the corresponding mean collector efficiency of 0.190, 0.205 and 0.197 [-], respectively. The working fluid flowrate, the collector length and the range of time that gave rise to maximum results were: 0.0093 [kg/s], 2.0 [m] and 12PM - 13.00PM, respectively. There was good agreement between the computed and the measured working fluid temperatures. The results obtained are useful for the optimal design of the solar collector and its operations.

Oko C.O.C.

2012-01-01

339

Low and medium temperature solar thermal collector based in innovative materials and improved heat exchange performance  

International Nuclear Information System (INIS)

Highlights: • We designed, built and tested 2 different prototypes of thermal collector. • We included polymeric materials and suppressed pipes for freeform optimization. • Efficiency of the collector achieved values as high as commercial ones. • We provided a low cost and high volume production product. - Abstract: A low and medium temperature solar thermal collector for economical supply of heat between 40 and 90 °C has been developed. It is based on solar concentrating systems, heat transfer optimization and substitution of metallic materials by plastic ones. The basic concept is the integration of a flat absorber strip inside semicircular reflector channels in contact with heated water without pressurization. This collector is intended to be more efficient and cheaper than what actual commercial collectors usually are so that the access to a clean and renewable energy would be more quickly redeemable and its use more effective during its life cycle, expanding its common application range. The substitution of traditional materials by surface treated Aluminum with TiNOx for the absorber and chromed thermoformed ABS for the reflector simplifies the production and assembly process. The definitive prototype has an aperture area of 0.225 m2. It was tested in Zaragoza (Spain) and the accumulated efficiency was between 41% and 57%, and the instantaneous efficiency reached 98% depending on the weather conditions. As all trials were made in parallel with a commercial collector, in several cases the performance was over the commercial one

340

High-performance carbon-based supercapacitors using Al current-collector with conformal carbon coating  

International Nuclear Information System (INIS)

Al current-collector with porous surface is coated with a conformal carbon (C) layer via a chemical vapor deposition process in CH4 at 600 deg. C. X-ray photoelectron spectroscopy analysis indicates that the coating process leads to the replacement of native aluminum oxide with a composite coating consisting of an Al4C3 interfacial layer and a C top layer. Activated C-based supercapacitors employing the resulting C-coated Al current-collectors have exhibited remarkably enhanced high-rate performance, and the enhancement can be attributed to two accounts. Firstly, the current-collector/active-layer interface resistance is reduced due to removal of the insulating oxide layer and improved adhesion of the active-layer on the current-collector. Secondly, the presence of the conducting C layer shortens the effective current conduction distance from the solid-electrolyte interface to the current-collector, leading to reduced charge-transfer resistance within the active-layer. Combining the C-coated Al current-collector with a C fiber active-layer that contains a large mesoporous pore volume (0.4 cm3 g-1) has resulted in high-performance supercapacitors that exhibit, for instance, a cell specific energy of 18 Wh Kg-1 at 25 deg. C or 7 Wh Kg-1 at -10 deg. C under a cell specific power of 25 KW Kg-1.

341

A system for the comparison of tools for the simulation of water-based radiant heating and cooling systems  

DEFF Research Database (Denmark)

Low temperature heating and high temperature cooling systems such as thermally activated building systems (TABS) offer the chance to use low exergy sources, which can be very beneficial financially as well as ecologically when using renewable energy sources. The above has led to a considerable increase of water based radiant systems in modern buildings and a need for reliable simulation tools to predict the indoor environment and energy performance. This paper describes the comparison of the building simulation tools IDA ICE, IES , EnergyPlus and TRNSYS. The simulation tools are compared to each other using the same room and boundary conditions. The results show significant differences in predicted room temperatures, heating and cooling degree hours as well as thermal comfort in winter and summer.

Behrendt, Benjamin; Raimondo, Daniela

2011-01-01

342

General Relativistic Radiant Shock Waves in the Post-Quasistatic Approximation  

International Nuclear Information System (INIS)

An evolution of radiant shock wave front is considered in the framework of a recently presented method to study self-gravitating relativistic spheres, whose rationale becomes intelligible and finds full justification within the context of a suitable definition of the post-quasistatic approximation. The spherical matter configuration is divided into two regions by the shock and each side of the interface having a different equation of state and anisotropic phase. In order to simulate dissipation effects due to the transfer of photons and/or neutrinos within the matter configuration, we introduce the flux factor, the variable Eddington factor and a closure relation between them. As we expected the strong of the shock increases the speed of the fluid to relativistic ones and for some critical values is larger than light speed. In addition, we find that energy conditions are very sensible to the anisotropy, specially the strong energy condition. As a special feature of the model, we find that the contribution of the matter and radiation to the radial pressure are the same order of magnitude as in the mant as in the core, moreover, in the core radiation pressure is larger than matter pressure

343

ADVANCED HYBRID PARTICULATE COLLECTOR - PHASE III  

Energy Technology Data Exchange (ETDEWEB)

A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the U.S. Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in a unique configuration. The AHPC concept consists of a combination of fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two collection methods, both in the particulate collection step and in the transfer of dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emission with conventional ESPs, and it solves the problem of reentrainment and re-collection of dust in conventional baghouses. In Phase II, a 2.5-MW-scale AHPC was designed, constructed, installed, and tested at the Big Stone power station. For Phase III, further testing of an improved version of the 2.5-MW-scale AHPC at the Big Stone power station is being conducted to facilitate commercialization of the AHPC technology.

Stanley J. Miller; Ye Zhuang; Michael E. Collings; Michelle R. Olderbak

2000-10-01

344

Participation in multilateral effort to develop high performance integrated CPC evacuated collectors  

Science.gov (United States)

The University of Chicago Solar Energy Group has had a continuing program and commitment to develop an advanced evacuated solar collector integrating nonimaging concentration into its design. During the period from 1985-1987, some of our efforts were directed toward designing and prototyping a manufacturable version of an Integrated Compound Parabolic Concentrator (ICPC) evacuated collector tube as part of an international cooperative effort involving six organizations in four different countries. This 'multilateral' project made considerable progress towards a commercially practical collector. One of two basic designs considered employed a heat pipe and an internal metal reflector CPC. We fabricated and tested two large diameter (125 mm) borosilicate glass collector tubes to explore this concept. The other design also used a large diameter (125 mm) glass tube but with a specially configured internal shaped mirror CPC coupled to a U-tube absorber. Performance projections in a variety of systems applications using the computer design tools developed by the International Energy Agency (IEA) task on evacuated collectors were used to optimize the optical and thermal design. The long-term goal of this work continues to be the development of a high efficiency, low cost solar collector to supply solar thermal energy at temperatures up to 250 C. Some experience and perspectives based on our work are presented and reviewed. Despite substantial progress, the stability of research support and the market for commercial solar thermal collectors were such that the project could not be continued. A cooperative path involving university, government, and industrial collaboration remains the most attractive near term option for developing a commercial ICPC.

Winston, R.; Ogallagher, J. J.

1992-05-01

345

Experimental investigation and thermodynamic performance analysis of a solar dryer using an evacuated-tube air collector  

International Nuclear Information System (INIS)

Highlights: ? We evaluate an evacuated-tube solar air collector and use it to develop a novel dryer. ? Apple, carrot and apricot thin-layer drying experiments are conducted. ? Best overall fitting among several available thin-layer drying models is pursued. ? Thermodynamic analysis yields optimal collector area, energy utilization/exergy loss. ? The proposed dryer has a capacity for drying larger quantities of products. -- Abstract: The present work presents a thermodynamic performance analysis of a solar dryer with an evacuated-tube collector. Drying experiments for apples, carrots and apricots were conducted, after a preliminary stage of the investigation which included measurements for the determination of the collector efficiency. These results showed that the warm outlet air of the collector attains temperature levels suitable for drying of agricultural products without the need of preheating. Thus, the present collector was used as the heat source for a drying chamber in the frame of the development of a novel, convective, indirect solar dryer; given the fact that in the literature there are only a few studies about this type of collectors in conjunction with solar drying applications. Thin-layer drying models were fitted to the experimental drying curves, including the recent model of Diamante et al. which showed good correlation coefficients for all the tested products. Drying parameters such as moisture ratio and drying rates were calculated. Furthermore, an energetic/exergetic analysis of the dryer was also conducted and performance coefficients such as pick-up and exergy efficiencies, energy utilization ratio, exergy losses were determined for several configurations such as single and double-trays and several drying air velocities. On the other hand, an optimal collector surface area study was conducted, based on laws for minimum entropy generation. Design parameters such as optimum collector area were determined based on the minimum entropy generation number. The mass flow number, along with the maximum collector and fluid exit temperatures were studied in relation to the minimum entropy generation. The energy/exergy analysis proposed, provides a useful tool for the evaluation of this type of collectors regarding their effectiveness as part of a solar drying system. Moreover, the results of the present study showed that the proposed solar dryer has a capacity for drying larger quantities of the products than those considered (in the frame of the experimental study) given the high efficiency of the collector. In general, the proposed system provides an interesting option for the penetration of this type of collectors in large-scale applications in the agricultural and industrial sector.

346

Modelling and analysis of a heating system for industrial application, using flat-plate solar-collectors with single and double cover glasses  

International Nuclear Information System (INIS)

A calculational methodology for dimensioning a flat-plate solar-collector arrangement, which fulfils the energy requirement of a heat transfer system in one of the steps of the uranium recovery process, from the uranium-phosphorus ore at Itataia, Ceara, in Brazil. The PROSOL-1 and PROSOL-2 computer codes for determining the total area required by collector arrangement-with single and double cover glasses, respectively- taking into account the system design and meteorological conditions of the regions, were used. These codes optimize the series/parallel arranges of collectors in the whole complex and, determine the water flow in each system and the average efficiency of the collector arrangement. The technical and economical feasibility for both collector arrangement with single and double cover glasses, were verified. It was concluded that, the last one is more advantageous, allowing a reduction of 30% in the total collector area. (M.C.K.)

347

Análisis de los parámetros para el diseño y optimización de un tubo radiante / Analysis of the relevant parameters for the design and optimization of a radiant tube  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish La necesidad de apropiar tendencias tecnológicas de última generación en equipos de combustión con aplicaciones en el sector productivo nacional, despierta el interés por estudiar los parámetros de diseño, optimización y caracterización de nuevos sistemas térmicos. En este artículo se presenta un mé [...] todo para el análisis de procesos de calentamiento con tubo radiante. El modelo se ha desarrollado planteando algunas hipótesis que ayudan a la caracterización de los parámetros mas influyentes involucrados en su funcionamiento y tiene como objetivos servir de guía en la etapa de diseño en aplicaciones industriales y ser una herramienta adecuada para la selección de un sistema de combustión con tubo radiante. Abstract in english The need for adopting the latest technological tendencies in combustion appliances, which have potential applications in the national industry, gives rise to an interest in studying the parameters of design, optimization and characterization of new thermal systems. A method for the analysis of heat [...] transfer processes involving radiant tubes is presented in this article. Some hypotheses used in the development of the model considered helpful for the characterization of the most influencing parameters involved in the model are presented. The model attempts to serve as a guide during the design phase in in¬dustrial applications, and to be an adequate tool for the selection of a combustion system with radiant tube.

Andrés, Amell Arrieta; Henry, Copete López; Juan Pablo, Gómez.

2006-09-01

348

Two new designs of parabolic solar collectors  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, two new compound parabolic trough and dish solar collectors are presented with their working principles. First, the curves of mirrors are defined and the mathematical formulation as one analytical method is used to trace the sun rays and recognize the focus point. As a result of the ray tracing, the distribution of heat flux around the inner wall can be reached. Next, the heat fluxes are calculated versus several absorption coefficients. These heat flux distributions around absorber tube are functions of angle in polar coordinate system. Considering, the achieved heat flux distribution are used as a thermal boundary condition. After that, Finite Volume Methods (FVM are applied for simulation of absorber tube. The validation of solving method is done by comparing with Dudley's results at Sandia National Research Laboratory. Also, in order to have a good comparison between LS-2 and two new designed collectors, some of their parameters are considered equal with together. These parameters are consist of: the aperture area, the measures of tube geometry, the thermal properties of absorber tube, the working fluid, the solar radiation intensity and the mass flow rate of LS-2 collector are applied for simulation of the new presented collectors. After the validation of the used numerical models, this method is applied to simulation of the new designed models. Finally, the outlet results of new designed collector are compared with LS-2 classic collector. Obviously, the obtained results from the comparison show the improving of the new designed parabolic collectors efficiency. In the best case-study, the improving of efficiency are about 10% and 20% for linear and convoluted models respectively.

Karimi Sadaghiyani Omid

2014-01-01

349

Bioinspired plate-based fog collectors.  

Science.gov (United States)

In a recent work, we explored the feeding mechanism of a shorebird to transport liquid drops by repeatedly opening and closing its beak. In this work, we apply the corresponding results to develop a new artificial fog collector. The collector includes two nonparallel plates. It has three advantages in comparison with existing artificial collectors: (i) easy fabrication, (ii) simple design to scale up, and (iii) active transport of condensed water drops. Two collectors have been built. A small one with dimensions of 4.2 × 2.1 × 0.05 cm(3) (length × width × thickness) was first built and tested to examine (i) the time evolution of condensed drop sizes and (ii) the collection processes and efficiencies on the glass, SiO2, and SU-8 plates. Under similar experimental conditions, the amount of water collected per unit area on the small collector is about 9.0, 4.7, and 3.7 times, respectively, as much as the ones reported for beetles, grasses, and metal wires, and the total amount of water collected is around 33, 18, and 15 times. On the basis of the understanding gained from the tests on the small collector, a large collector with dimensions of 26 × 10 × 0.2 cm(3) was further built and tested, which was capable of collecting 15.8 mL of water during a period of 36 min. The amount of water collected, when it is scaled from 36 to 120 min, is about 878, 479, or 405 times more than what was collected by individual beetles, grasses, or metal wires. PMID:25192549

Heng, Xin; Luo, Cheng

2014-09-24

350

Comparison of different methods of estimating the mean radiant temperature in outdoor thermal comfort studies.  

Science.gov (United States)

Correlations between outdoor thermal indices and the calculated or measured mean radiant temperature T(mrt) are in general of high importance because of the combined effect on human energy balance in outdoor spaces. The most accurate way to determine T(mrt) is by means of integral radiation measurements, i.e. measuring the short- and long-wave radiation from six directions using pyranometers and pyrgeometers, an expensive and not always an easily available procedure. Some studies use globe thermometers combined with air temperature and wind speed sensors. An alternative way to determine T(mrt) is based on output from the RayMan model from measured data of incoming global radiation and morphological features of the monitoring site in particular sky view factor (SVF) data. The purpose of this paper is to compare different methods to assess the mean radiant temperature T(mrt) in terms of differences to a reference condition (T(mrt) calculated from field measurements) and to resulting outdoor comfort levels expressed as PET and UTCI values. The T(mrt) obtained from field measurements is a combination of air temperature, wind speed and globe temperature data according to the forced ventilation formula of ISO 7726 for data collected in Glasgow, UK. Four different methods were used in the RayMan model for T(mrt) calculations: input data consisting exclusively of data measured at urban sites; urban data excluding solar radiation, estimated SVF data and solar radiation data measured at a rural site; urban data excluding solar radiation with SVF data for each site; urban data excluding solar radiation and including solar radiation at the rural site taking no account of SVF information. Results show that all methods overestimate T(mrt) when compared to ISO calculations. Correlations were found to be significant for the first method and lower for the other three. Results in terms of comfort (PET, UTCI) suggest that reasonable estimates could be made based on global radiation data measured at the urban site or as a surrogate of missing SR data or globe temperature data recorded at the urban area on global radiation data measured at a rural location. PMID:24375056

Krüger, E L; Minella, F O; Matzarakis, A

2014-10-01

351

Simulation of solar lithium bromide-water absorption cooling system with parabolic trough collector  

International Nuclear Information System (INIS)

Ahwaz is one of the sweltering cities in Iran where an enormous amount of energy is being consumed to cool residential places in a year. The aim of this research is to simulate a solar single effect lithium bromide-water absorption cooling system in Ahwaz. The solar energy is absorbed by a horizontal N-S parabolic trough collector and stored in an insulated thermal storage tank. The system has been designed to supply the cooling load of a typical house where the cooling load peak is about 17.5 kW (5 tons of refrigeration), which occurs in July. A thermodynamic model has been used to simulate the absorption cycle. The working fluid is water, which is pumped directly to the collector. The results showed that the collector mass flow rate has a negligible effect on the minimum required collector area, but it has a significant effect on the optimum capacity of the storage tank. The minimum required collector area was about 57.6 m2, which could supply the cooling loads for the sunshine hours of the design day for July. The operation of the system has also been considered after sunset by saving solar energy

352

Comparative performance of two types of evacuated tube solar collectors in a residential heating and cooling system. The progress report  

Energy Technology Data Exchange (ETDEWEB)

Two types of evacuated tube solar collectors have been operated in space heating, cooling and domestic hot water heating systems in Colorado State University Solar House I. An experimental collector from Corning Glass Works supplied heat to the system from January 1977 through February 1978, and an experimental collector from Philips Research Laboratory, Aachen, which is currently in use, has been operating since August 1978. A flat absorber plate inside a single-walled glass tube is used in the Corning design, whereas heat is conducted through a single glass wall to an external heat exchanger plate in the Philips collector. In comparison with conventional flat-plate collectors, both types show reduced heat losses and improved efficiency. For space heating and hot water supply in winter, the solar delivery efficiency of the Corning collector ranged from 49% to 60% of the incident solar energy. The portion of the space heating and domestic hot water load carried by solar energy through fall and winter ranged from 50% to 74%, with a four-month contribution of 61% of the total requirements. Data on the Philips collector are currently being analyzed.

Conway, T.M.; Duff, W.S.; Lof, G.O.G.; Pratt, R.G.

1979-01-01

353

Designing, Construction and Analysis of Speed Control System of the Fan with PV Feeding Source in an Air Solar Collector  

Directory of Open Access Journals (Sweden)

Full Text Available Solar energy is one of the renewable energy sources which can be received more by designing more accurate systems. In this article a flat solar collector with the area of 2×1m2 and thickness of 0.5mm, made of steel iron in the form of venetian blinds (in order to increase exposure to air has been used. The surface of absorber plate was black and for insulation of the body of the collector glass wool has been used with 5 cm thickness. One of the essential problems of air solar collectors is that the temperature of the exiting air temperature from the collector is variable during the day and their efficiency is low in the last hours of the day and also when the weather suddenly gets cloudy .In this study, to keep constant the exiting air from the collector consistent in the desired limits, a control system is designed and constructed by applying photovoltaic cells, a microcontroller (AVR and temperature sensors (LM35. Three temperature sensors were installed in the exit of the collector .The experiment results showed that by automatic change of the fan's speed in the designed system, the exiting temperature of the collector was obtained in the desired limits which is an outstanding advantage for various applications.

Amir Hematian

2011-12-01

354

Efficiencies of flat plate solar collectors at different flow rates  

DEFF Research Database (Denmark)

Two flat plate solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one collector is equipped with an ETFE foil between the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rate are obtained. The calculated efficiencies are in good agreement with the measured efficiencies.

Chen, Ziqian; Furbo, Simon

2012-01-01

355

Integrated main rail, feed rail, and current collector  

Energy Technology Data Exchange (ETDEWEB)

A separator plate is described for a fuel cell comprising an anode current collector, a cathode current collector and a main plate, the main plate disposed between the anode current collector and the cathode current collector. The anode current collector forms a flattened peripheral wet seal structure and manifold wet seal structure on the anode side of the separator plate and the cathode current collector forms a flattened peripheral wet seal structure and manifold wet seal structure on the cathode side of the separator plate. In this manner, the number of components required to manufacture and assemble a fuel cell stack is reduced. 9 figs.

Petri, R.J.; Meek, J.; Bachta, R.P.; Marianowski, L.G.

1994-11-08

356

Integrated main rail, feed rail, and current collector  

Energy Technology Data Exchange (ETDEWEB)

A separator plate for a fuel cell comprising an anode current collector, a cathode current collector and a main plate, the main plate disposed between the anode current collector and the cathode current collector. The anode current collector forms a flattened peripheral wet seal structure and manifold wet seal structure on the anode side of the separator plate and the cathode current collector forms a flattened peripheral wet seal structure and manifold wet seal structure on the cathode side of the separator plate. In this manner, the number of components required to manufacture and assemble a fuel cell stack is reduced.

Petri, Randy J. (Crete, IL); Meek, John (Downers Grove, IL); Bachta, Robert P. (Chicago, IL); Marianowski, Leonard G. (Mount Prospect, IL)

1994-01-01

357

Thermodynamic model to study a solar collector for its application to Stirling engines  

International Nuclear Information System (INIS)

Highlights: • A thermodynamic model is presented to study a solar collector for its application to Stirling engines. • The parabolic collector is analyzed based on optical and thermal. • Effects of changing some conditions and parameters are studied. - Abstract: Energy production through clean and green sources has been paid attention over the last decades owing to high energy consumption and environmental emission. Solar energy is one of the most useful energy sources. Due to high investment cost of centralized generation of electricity and considerable loss in the network, it is necessary to look forward to decentralized electricity generation technologies. Stirling engines have high efficiency and are able to be coupled with solar energy which cannot be applied in internal combustion engines. Solar Stirling engines can be commercialized and used to generate decentralized electricity in small to medium levels. One of the most important steps to set up an efficient solar Stirling engine is choosing and designing the collector. In this study, a solar parabolic collector with 3500 W of power for its application to Stirling engines was designed and analyzed (It is the thermal inlet power for a Stirling engine). We studied the parabolic collector based on optical and thermal analysis. In this case, solar energy is focused by a concentrating mirror and transferred to a pipe containing fluid. MATLAB software was used for obtaining the parameters of the collector, with respect to the geographic, temporal, and environmental conditions, fluid inlet temperature and some other considerations. After obtaining the results of the design, we studied the effects of changing some conditions and parameters such as annular space pressure, type of the gas, wind velocity, environment temperature and absorber pipe coating

358

Modeling of a solar collectors absorber  

Energy Technology Data Exchange (ETDEWEB)

The heat flow in the absorber of a solar collector occupies a definite space in which heat is spread by conduction. If the temperature is known at any time and any point of this space, the process can be mathematically studied. This paper provided a mathematical description for the heat conduction proceeding on the plane surface of a solar collector's absorber divided into three parts, for which the Laplace equation was formed with boundary conditions. The purpose of the paper was to mathematically describe the heat conduction process initiating in the plane part of a collector's absorber, then passing to a tube and from the tube to the liquid flowing through it. The process was considered stationary, independent of time, and, therefore the temperature field was obtained in spatial coordinates. Specifically, the paper discussed the equations for the temperature field in the collector absorber, including the temperature field in the plate between tubes; the temperature field in the tube's coating; and the temperature field in the liquid. It was concluded that the proposed mathematical description could assist in finding the optimal sizes for the absorber, which, taken for the whole collector, would provide its maximum efficiency. 2 refs.

Shipkovs, P.; Vanags, M.; Kashkarova, G.; Lebedeva, K.; Shipkovs, J. [Inst. of Physical Energetics, Riga (Latvia); Barkans, V. [Latvian Maritime Academy, Riga (Latvia); Jirgens, M. [Latvian Ministry of Environment, Riga (Latvia)

2008-07-01

359

A calibrated integrating sphere setup to determine the infrared spectral radiant flux of high-intensity discharge lamps  

Science.gov (United States)

A setup that aims to determine the infrared radiation fraction of the energy balance of high intensity discharge (HID) lamps has been designed, constructed and calibrated. It consists of a high-resolution integrating sphere that can cover a wide spectral range. New in this work is that the integrating sphere measurements can be used in the infrared part of the spectrum up to 10 µm and that we have calibrated the absolute intensity in that range. No calibration standards for spectral radiant flux are readily available in the infrared. Therefore, we have used a resistive heated platinum ribbon as absolute intensity reference. As a first test case, this new setup was used to determine the energy balance of a Philips CDM-T 70W/830 lamp, which is a type of metal halide HID lamp.

Rijke, A. J.; Nijdam, S.; Haverlag, M.; Janssen, J. F. J.; van der Mullen, J. J. A. M.; Kroesen, G. M. W.

2011-06-01

360

A calibrated integrating sphere setup to determine the infrared spectral radiant flux of high-intensity discharge lamps  

International Nuclear Information System (INIS)

A setup that aims to determine the infrared radiation fraction of the energy balance of high intensity discharge (HID) lamps has been designed, constructed and calibrated. It consists of a high-resolution integrating sphere that can cover a wide spectral range. New in this work is that the integrating sphere measurements can be used in the infrared part of the spectrum up to 10 ?m and that we have calibrated the absolute intensity in that range. No calibration standards for spectral radiant flux are readily available in the infrared. Therefore, we have used a resistive heated platinum ribbon as absolute intensity reference. As a first test case, this new setup was used to determine the energy balance of a Philips CDM-T 70W/830 lamp, which is a type of metal halide HID lamp.

361

Validation of a dynamic model for unglazed collectors including condensation. Application for standardized testing and simulation in TRNSYS and IDA  

OpenAIRE

An improved unglazed collector model has been validated for use in TRNSYS and IDA and also for future extension of the EN12975 collector test standard. The basic model is the same as used in the EN12975 test standard in the quasi dynamic performance test method (QDT). In this case with the addition of a condensation term that can handle the operation of unglazed collectors below the dew point of the air. This is very desirable for simulation of recharging of ground source energy systems and d...

Perers, Bengt; Kovacs, Peter; Pettersson, Ulrik; Bjo?rkman, Johan; Martinsson, Carina; Eriksson, Jo?rgen

2012-01-01

362

Thermal and optical study of parabolic trough collectors of Shiraz solar power plant  

Energy Technology Data Exchange (ETDEWEB)

The construction of the first 250 KW solar power plant in Shiraz, Iran was discussed. The power plant is comprised of a steam and oil cycle which includes 48 parabolic trough collectors (PTCs). Solar thermal power plants based on PTCs are currently the most successful solar technologies for electricity generation. These power plants are basically composed of a solar collector field and a power block. The solar collector field is designed to collect heat from the sun which it is continuously tracking. The reflecting surface concentrates direct solar radiation in the optical focal line of the collector where the heat collecting element (HCE) is located. The HCE absorbs the reflected energy and transmits it to the heat transfer fluid which is pumped to the conventional power block where electricity is generated. There is potential to significantly increase the performance and reduce the cost of PTC solar thermal electric technologies. However, it is necessary to characterize the optical performance and determine the optical losses of PTCs in order to improve the optical efficiency of these systems and to ensure the desired power quality. In this study, thermocouple sensors were used to record the collector oil inlet and outlet temperature along with the ambient temperature in the PTCs. In addition to measuring the wind speed, the solar beam radiation intensity was measured along with the oil's mass flow rate. All parameters were measured as a function of time. Based on these measurements, the intercept factor value and collector's incidence angle was determined and compared with other large size constructed commercial parabolic collectors. The maximum beam radiation during the experimental period was 735 2mW. The useful heat gain and the collector's instantaneous efficiency as a whole was evaluated on an hourly basis. All these parameters were strongly influenced by the incident beam radiation and found to follow each other. The optical and thermal efficiency of the collector was about 69 and 64 per cent respectively, which was less than the other installed parabolic collectors. It was concluded that improvements could be made by better tracking and by cleaning the mirror and glass tube cover. 17 refs., 3 tabs., 7 figs.

Mokhtari, A.; Yaghoubi, M.; Vadiee, A.; Hessami, R. [Shiraz Univ, Shiraz (Iran, Islamic Republic of); Kanan, P. [Renewable Energy Organization of Iran, Tehran (Iran, Islamic Republic of)

2007-07-01

363

CISBAT 2007 - Solar collectors (heat and electricity)  

Energy Technology Data Exchange (ETDEWEB)

This is the third part of the proceedings of the 2007 CISBAT conference on Renewables in a changing climate, held in Lausanne, Switzerland. On the subject of Building and urban integration of renewables the following oral contributions are summarised: 'Facade integration of solar thermal collectors: present and future', 'Long term experiences with a versatile PV in roof system', 'Development of a design and performance prediction tool for the ground source heat pump and underground thermal storage system', 'Hygrothermal performance of earth-to-air heat exchanger: long-term data evaluation and short-term simulation' as well as 'The real cost of heating your home: a comparative assessment of home energy systems with external costs'. Poster-sessions on the subject include 'Central solar heating plants with seasonal heat storage', 'Analysis of forced convection for evaporative air flow and heat transfer in PV cooling channels', 'Renewable energy technology in Mali: constraints and options for a sustainable development', 'Effect of duct width in ducted photovoltaic facades', 'Design and actual measurement of a ground source heat pump system using steel foundation piles as ground heat exchangers', 'Development of an integrated water-water heat pump unit for low energy house and its application', 'PV effect in multilayer cells and blending of fullerene/poly (3-hexylthiophene) and phthalocyanine having NIR charge transfer absorption band', 'CdTe photovoltaic systems - an alternative energetic', 'Integration of renewable energy sources in a town, examples in Grenoble', 'A prospective analysis method for the conception of solar integration solutions in buildings' and 'Energy and aesthetic improvements for building integration of cost effective solar energy systems'. Further groups of presentations at the conference are reported on in separate database records. An index of authors completes the proceedings.

NONE

2007-07-01

364

An experimental study of thermal comfort at different combinations of air and mean radiant temperature  

DEFF Research Database (Denmark)

It is often discussed if a person prefers a low air temperature (ta) and a high mean radiant temperature (tr), vice-versa or it does not matter as long as the operative temperature is acceptable. One of the hypotheses is that it does not matter for thermal comfort but for perceived air quality, a lower air temperature is preferred. This paper presents an experimental study with 30 human subjects exposed to three different combinations of air- and mean radiant temperature with an operative temperature around 23 °C. The subjects gave subjective evaluations of thermal comfort and perceived air quality during the experiments. The PMV-index gave a good estimation of thermal sensation vote (TSV) when the air and mean radiant temperature were the same. In the environment with different air- and mean radiant temperatures, a thermal comfort evaluation shows an error up to 1 scale unit on the 7-point thermal sensation scale. The study could not confirm any preference regarding air and mean radiant temperature.

Simone, Angela; Olesen, Bjarne W.

2009-01-01

365

[Effect of ambient atmosphere on laser micro-plasma radiant intensity].  

Science.gov (United States)

The plasma radiant intensity was investigated by a laser micro-plasma spectral analysis system. The system consists of an YJG-II laser micro-spectral analyzer and a CCD data acquisition and processing system. National standard soil samples were studied in the experiment under different ambient atmosphere with argon, helium and the mixture of argon and helium by using the analysis lines, Ca II 393.367 nm and Ca II 396.847 nm. The results of this research suggest that both the time of plasma illumination and the radiant intensity of plasma in an atmosphere of helium-argon mixture were better than that in pure helium or argon gas. The plasma radiant intensity was obviously enhanced when the proportion of helium and argon was 66.7% and 33.3%, respectively. Under these conditions, the influence of the height of auxiliary electrode on laser micro-plasma radiant intensity was also investigated. The maximum laser micro-plasma radiant intensity was reached when the height of auxiliary electrode was 3 mm. PMID:20038018

Guo, Qing-Lin; Han, Mei-Ying; Zhang, Lei; Zhang, Qiu-Lin; Zhang, Jin-Ping; Chen, Jin-Zhong

2009-10-01

366

Heat transfer characteristics of a linear solar collector.  

Science.gov (United States)

The heat transfer characteristics of a linear solar energy collector are calculated as functions of dimensions, spectral quality of the selective absorber surface, optical flux concentration of the optical configuration, and thermal parameters and flow rate of the heat transfer medium. Carnot efficiency, exit temperature, and an upper limit to the amount of heat extracted are determined for systems in which liquid sodium serves as the heat transfer medium. The performance is evaluated for selective absorber surfaces representing the state of the art as well as for surfaces requiring a more mature thin-film technology. PMID:20125288

Seraphin, B O

1973-02-01

367

Domestic oven heated by a concentrating solar collector  

OpenAIRE

A project to power a domestic oven by solar energy was developed. The focal axis of a cylindrical parabolic reflector usually reaches temperatures of up to 250ºC. A heat transfer fluid carries this heat to the heat exchanger in the oven. Current domestic ovens are generally electric and can reach 250ºC with a power of 2-3 kW. The installation is composed of pumps, valves, thermally insulated pipes, exchanger, etc. These elements transfer the heat collected by the solar collector to the o...

Lloveras Macia?, Joaqui?n

2014-01-01

368

Potency of Solar Energy Applications in Indonesia  

Directory of Open Access Journals (Sweden)

Full Text Available Currently, 80% of conventional energy is used to fulfill general public's needs andindustries. The depletion of oil and gas reserves and rapid growth in conventional energyconsumption have continuously forced us to discover renewable energy sources, like solar, wind,biomass, and hydropower, to support economic development in the future. Solar energy travels at aspeed of 186,000 miles per second. Only a small part of the radiant energy that the sun emits intospace ever reaches the Earth, but that is more than enough to supply all our energy demand.Indonesia is a tropical country and located in the equator line, so it has an abundant potential ofsolar energy. Most of Indonesian area get enough intensity of solar radiation with the average dailyradiation around 4 kWh/m2. Basically, the solar systems use solar collectors and concentrators forcollecting, storing, and using solar radiation to be applied for the benefit of domestics, commercials,and industrials. Common applications for solar thermal energy used in industry are the SWHs, solardryers, space heating, cooling systems and water desalination.

Dessy Ariyanti

2012-07-01

369

SELECTIVE ABSORBER COATED FOILS FOR SOLAR COLLECTORS  

Energy Technology Data Exchange (ETDEWEB)

Solar absorber metal foils are discussed in terms of materials and basic processing science. Also included is the use of finished heavy sheet stock for direct fabrication of solar collector panels. Both the adhesives and bonding methods for foils and sheet are surveyed. Developmental and representative commercial foils are used as illustrative examples. As a result it was found that foils can compete economically with batch plating but are limited by adhesive temperature stability. Also absorber foils are very versatile and direct collector fabrication from heavy foils appears very promising.

Lampert, Carl M.

1980-04-01

370

Design of gas filled solar collectors  

OpenAIRE

With a suitable gas filling used between cover glass and absorber in a flat plate solar collector, it is possible achieving better thermal performance at the same time as the distance betweenabsorber and glass can be reduced. Though, even if there is no vacuum inside the box, there will be potential risks for exhaustion due to stresses depending on the gas volume varies as the temperature varies. This study found out that it is possible build such a collector with less material in the absorbe...

Vestlund, Johan; Dalenba?ck, Jan-olof; Ro?nnelid, Mats

2010-01-01

371

Qualification test and analysis report: solar collectors  

Energy Technology Data Exchange (ETDEWEB)

Test results show that the Owens-Illinois Sunpak/sup TM/ Model SEC 601 air-cooled collector meets the national standards and codes as defined in the Subsystem Performance Specification and Verification Plan of NASA/MSFC Contract NAS8-32259, dated October 28, 1976. The architectural and engineering firm of Smith, Hinchman and Grylls, Detroit, Michigan, acted in the capacity of the independent certification agency. The program calls for the development, fabrication, qualification and delivery of an air-liquid solar collector for solar heating, combined heating and cooling, and/or hot water systems.

1978-12-01

372

Indoor thermal performance evaluation of Daystar solar collector  

Science.gov (United States)

The test procedures used and results obtained from a test program to obtain thermal performance data on a Daystar Model 21B, S/N 02210, Unit 2, liquid solar collector under simulated conditions are described. The test article is a flat plate solar collector using liquid as a heat transfer medium. The absorber plate is copper and coated with black paint. Between the tempered low iron glass and absorber plate is a polycarbonate trap used to suppress convective heat loss. The collector incorporates a convector heat dump panel to limit temperature excursions during stagnation. The following tests were conducted: (1) collector thermal efficiency; (2) collector time constant; (3) collector incident angle modifier; (4) collector heat loss coefficient; and (5) collector stagnation.

Shih, K., Sr.

1977-01-01

373

Development of a low-temperature, low-cost, black liquid solar collector. Final report, September 12, 1977-October 31, 1978  

Energy Technology Data Exchange (ETDEWEB)

Battelle's Columbus Laboratories (BCL) has developed an efficient, low-cost, low-temperature, nonconcentrating, liquid-heating solar collector suitable for use as a thermal energy source for heat pumps or other heating applications. The collector incorporates a black liquid heat transfer medium permitting solar radiation to be absorbed directly by the liquid. Based on detailed measurements of the spectral absorption properties on many black liquids, and on the results of computer analysis of collector performance, it has been shown that the black liquid collector concept has the potential of significantly improved performance compared with an unglazed (i.e., swimming pool type) black-absorber collector of comparable cost.On the other hand, it has the potential of significant cost savings compared with the single-glazed collector of comparable performance. Experimental data obtained on two black liquid collectors constructed during this project closely match the predicted curves obtained from a theoretical computer analysis. Results of the systems analysis studies have shown that the black liquid collector, when used as a heat source for a solar-assisted heat pump, has comparable performance to that of a single-glazed conventional collector but at considerably lower cost. Another important result is that currently available heat pump systems are not ideally matched or compatible with a solar-assisted system. A solar-assisted system will require design of heat pumps which can take advantage of the higher system coefficient of performance (COP) possible with a heat source at elevated temperatures.

Landstrom, D K; Talbert, S G; Stickford, Jr, G H; Fischer, R D; Hess, R E

1978-10-01

374

Theoretical variations of the thermal performance of different solar collectors and solar combi systems as function of the varying yearly weather conditions in Denmark  

DEFF Research Database (Denmark)

The thermal performances of solar collectors and solar combi systems with different solar fractions are studied under the influence of the Danish Design Reference Year, DRY data file, and measured weather data from a solar radiation measurement station situated at the Technical University of Denmark in Kgs. Lyngby. The data from DRY data file are used for any location in Denmark. The thermal performances of the solar heating systems are calculated by means of validated computer models. The measured yearly solar radiation varies by approximately 23% in the period from 1990 until 2002, and the investigations show that it is not possible to predict the yearly solar radiation on a tilted surface based on the yearly global radiation. The annual thermal performance of solar combi systems cannot with reasonable approximation be fitted to a linear function of the annual total radiation on the solar collector or the annual global radiation. Solar combi systems with high efficient solar collectors are more influenced by weather variations from one year to another than systems with low efficient solar collectors. The annual thermal performance of solar collectors cannot be predicted from the global radiation, but both the annual thermal performance and the annual utilized solar energy can with a reasonable approximation be fitted to a linear function of the yearly solar radiation on the collector for both flat plate and evacuated tubular solar collectors. Also evacuated tubular solar collectors utilize less sunny years with large parts of diffuse radiation relatively better than flat plate collectors.

Andersen, Elsa; Furbo, Simon

2009-01-01

375

Agronomical and biological results of solar energy heating by the combination of the sunstock system with an outside captor on a muskmelon crop grown in polyethylene greenhouses  

Directory of Open Access Journals (Sweden)

Full Text Available Six cultivars of muskmelon (Early Dew, "68-02", "Early Chaca", "Jivaro", "Super Sprint" and "Cantor" transplanted at two differents dates were cultivated under two PE greenhouses heated by solar energy recovery and compared to a control greenhouse. The greenhouses were covered with a double shield of normal PE of 100 microns. The first greenhouse was considered as the control. The second one was equipped with a sunstock solar energy collector distribution system, consisting in a covering of 37 % of the ground surface by flat black PVC tubes, used during the day as a solar energy captor for heating the water of a basin and during the night as a radiant mulch for heating the greenhouse by emission of radiation warmth. The third greenhouse was equipped also with the same sunstock System, but connected with a supplementary outdoor collector by means of flat PE tubes corresponding to about 28 % covering of the greenhouse, and resulting in a more important energy stock, available for heating during the night. Minimum air temperature was raised by about 1, 5 and 2, 5°C respectively in the second and the third greenhouse, while the minimum soil temperature was raised with about 1 and 2°C respectively. Evolution of the maximum temperatures was more irregular and was depending also from the incident energy. Plant growth under the solar heated greenhouse was more accelerated, and resulted in an earlier fruitset, an earlier production and a higher total yield.

Vandevelde, R.

1983-01-01

376

KARAKTERISTIK PENGERINGAN CHIPS MANGGA MENGGUNAKAN KOLEKTOR SURYA KACA GANDA [Characteristics of Mango Chips Drying Using a Double Plated Solar Collector  

Directory of Open Access Journals (Sweden)

Full Text Available The objectives of this research were to study the characteristics of mango chips drying using a double plated solar collector. The materials used were sliced mangoes with the thickness of 3, 6, and 8 mm. The equipments used for this research were double plated solar collector, thermocouple, digital balance, thermometer, vacuum oven, and desiccators. The research parameters included the rate of heat energy absorbed by the double plated solar collector, the heat energy losses, the efficiency of the double plated solar collector and the moisture content of the chips. The results of this study suggested that the use of double plated solar collector could increase the temperature and the amount of heat energy, thus speed up the drying process of the mango chips. The energy needed to evaporate the moisture content in mango decreased in proportion to the increase in drying time. The difference in mango chips’ thickness resulted in different decrease rate in water content until it reached a constant state. The efficiency of the double plated solar collector was 77.82%.

Safrani

2012-12-01

377

Lightweight, low-cost solar energy collector  

Science.gov (United States)

A lightweight solar concentrator of the reflecting parabolic or trough type is realized via a thin reflecting film, an inflatable structural housing and tensioned fibers. The reflector element itself is a thin, flexible, specularly-reflecting sheet or film. The film is maintained in the parabolic trough shape by means of a plurality of identical tensioned fibers arranged to be parallel to the longitudinal axis of the parabola. Fiber ends are terminated in two identical spaced anchorplates, each containing a plurality of holes which lie on the desired parabolic contour. In a preferred embodiment, these fibers are arrayed in pairs with one fiber contacting the front side of the reflecting film and the other contacting the back side of the reflecting film. The reflective surface is thereby slidably captured between arrays of fibers which control the shape and position of the reflective film. Gas pressure in the inflatable housing generates fiber tension to achieve a truer parabolic shape.

Hochberg, Eric B. (Inventor); Costen, Michael K. (Inventor)

2006-01-01

378

Some new aspects of the coupon-collector's problem  

OpenAIRE

We extend the classical coupon collector's problem to one in which two collectors are simultaneously and independently seeking collections of $d$ coupons. We find, in finite terms, the probability that the two collectors finish at the same trial, and we find, using the methods of Gessel-Viennot, the probability that the game has the following ``ballot-like'' character: the two collectors are tied with each other for some initial number of steps, and after that the player who...

Myers, Amy N.; Wilf, Herbert S.

2003-01-01

379

Thermal Performance of a Solarus CPC-Thermal Collector  

OpenAIRE

The  aim  of  this  master  thesis  is  an  investigation  of  the  thermal  performance  of  a  thermal compound parabolic concentrating (CPC) collector from Solarus. The collector consists of two troughs with absorbers which are coated with different types of paint with  unknown  properties.  The  lower  and  upper  trough  of  the  collector  have  been  tested individually. In  order  to  accomplish  the  performance  of  the  two  collectors,  a  th...

S?umic?, Mersiha

2014-01-01

380

Circumferentially-segmented collector usable with a TWT  

Science.gov (United States)

A TWT collector has axially-positioned collector stages in which at least one of the stages includes a plurality of annularly-arranged stage segments. The collector enhances electron beam velocity sorting by facilitating a combination of (a) selecting axial electric field distributions with application of selected voltages to the axially-positioned collector stages and (b) selecting radial electric field distributions with application of selected voltages to the annularly-arranged stage segments.

Brown, II, Richard A. (Inventor)

2001-01-01

381

Experimental and numerical analysis of air and radiant cooling systems in offices  

DEFF Research Database (Denmark)

This paper analyses office cooling systems based on all air mixing ventilation systems alone or coupled with radiant ceiling panels. This last solution may be effectively applied to retrofit all air systems that are no longer able to maintain a suitable thermal comfort in the indoor environment, for example in offices with high thermal loads. This study was performed by means of CFD simulations previously validated through an experimental campaign performed in a full scale test room, simulating a typical two-desk office equipped with an all air mixing ventilation system. The numerical studies were then extended to the coupled mixing ventilation and cold radiant ceiling panels. In particular, attention was drawn on the evaluation of the main supply jet properties (throw and penetration length) and on the draft risk caused by the cold air drop into the occupied zone. The study shows that such a problem can be effectively reduced applying cold radiant ceiling panels. Udgivelsesdato: April

Corgnati, S. P.; Perino, M.

2009-01-01

382

Modeling of hydronic radiant cooling of a thermally homeostatic building using a parametric cooling tower  

International Nuclear Information System (INIS)

Highlights: • Investigated cooling of thermally homeostatic buildings in 7 U.S. cities by modeling. • Natural energy is harnessed by cooling tower to extract heat for building cooling. • Systematically studied possibility and conditions of using cooling tower in buildings. • Diurnal ambient temperature amplitude is taken into account in cooling tower cooling. • Homeostatic building cooling is possible in locations with large ambient T amplitude. - Abstract: A case is made that while it is important to mitigate dissipative losses associated with heat dissipation and mechanical/electrical resistance for engineering efficiency gain, the “architect” of energy efficiency is the conception of best heat extraction frameworks—which determine the realm of possible efficiency. This precept is applied to building energy efficiency here. Following a proposed process assumption-based design method, which was used for determining the required thermal qualities of building thermal autonomy, this paper continues this line of investigation and applies heat extraction approach investigating the extent of building partial homeostasis and the possibility of full homeostasis by using cooling tower in one summer in seven selected U.S. cities. Cooling tower heat extraction is applied parametrically to hydronically activated radiant-surfaces model-buildings. Instead of sizing equipment as a function of design peak hourly temperature as it is done in heat balance design-approach of selecting HVAC equipment, it is shown that the conditions of using cooling tower depend on both “design-peak” daily-mean temperature and the distribution of diurnal range in hourly temperature (i.e., diurnal temperature amplitude). Our study indicates that homeostatic building with natural cooling (by cooling tower alone) is possible only in locations of special meso-scale climatic condition such as Sacramento, CA. In other locations the use of cooling tower alone can only achieve homeostasis partially

383

Shroud boundary condition characterization experiments at the Radiant Heat Facility.  

Energy Technology Data Exchange (ETDEWEB)

A series of experiments was performed to better characterize the boundary conditions from an inconel heat source ('shroud') painted with Pyromark black paint. Quantifying uncertainties in this type of experimental setup is crucial to providing information for comparisons with code predictions. The characterization of this boundary condition has applications in many scenarios related to fire simulation experiments performed at Sandia National Laboratories Radiant Heat Facility (RHF). Four phases of experiments were performed. Phase 1 results showed that a nominal 1000 C shroud temperature is repeatable to about 2 C. Repeatability of temperatures at individual points on the shroud show that temperatures do not vary more than 10 C from experiment to experiment. This variation results in a 6% difference in heat flux to a target 4 inches away. IR camera images showed the shroud was not at a uniform temperature, although the control temperature was constant to about {+-}2 C during a test. These images showed that a circular shaped, flat shroud with its edges supported by an insulated plate has a temperature distribution with higher temperatures at the edges and lower temperatures in the center. Differences between the center and edge temperatures were up to 75 C. Phase 3 results showed that thermocouple (TC) bias errors are affected by coupling with the surrounding environment. The magnitude of TC error depends on the environment facing the TC. Phase 4 results were used to estimate correction factors for specific applications (40 and 63-mil diameter, ungrounded junction, mineral insulated, metal-sheathed TCs facing a cold surface). Correction factors of about 3.0-4.5% are recommended for 40 mil diameter TCs and 5.5-7.0% for 63 mil diameter TCs. When mounted on the cold side of the shroud, TCs read lower than the 'true' shroud temperature, and the TC reads high when on the hot side. An alternate method uses the average of a cold side and hot side TC of the same size to estimate the true shroud temperature. Phase 2 results compared IR camera measurements with TC measurements and measured values of Pyromark emissivity. Agreement was within measured uncertainties of the Pyromark paint emissivity and IR camera temperatures.

Suo-Anttila, Jill Marie; Nakos, James Thomas; Gill, Walter

2004-10-01

384

Experimental validation of dynamic simulation of the flat plate collector in a closed thermosyphon solar water heater  

DEFF Research Database (Denmark)

This work studies the dynamic simulation of thermosyphon solar water heater collector considering the weather conditions of a city in north of Iran. The simulation was done for clear and partly cloudy days. The useful energy, the efficiency diagrams, the inlet and the outlet of collector, center of the absorber and center of the glass cover temperatures, were obtained. The simulation results were then compared with the experimental results in fall and showed a good agreement.

Taherian, H.; Kolaei, Alireza Rezania

2011-01-01

385

Optimization of the Collection Efficiency of a Hexagonal Light Collector using Quadratic and Cubic B\\'ezier Curves  

OpenAIRE

Reflective light collectors with hexagonal entrance and exit apertures are frequently used in front of the focal-plane camera of a very-high-energy gamma-ray telescope to increase the collection efficiency of atmospheric Cherenkov photons and reduce the night-sky background entering at large incident angles. The shape of a hexagonal light collector is usually based on Winston's design, which is optimized for only two-dimensional optical systems. However, it is not known whet...

Okumura, Akira

2012-01-01

386

Development, testing, and certification of life sciences engineering solar collector  

Science.gov (United States)

Results are presented for the development of an air flat plate collector for use with solar heating, combined heating and cooling, and hot water systems. The contract was for final development, testing, and certification of the collector, and for delivery of a 320 square feet collector panel.

Caudle, J. M.

1978-01-01

387

Numerical and experimental analysis of a point focus solar collector using high concentration imaging PMMA Fresnel lens  

International Nuclear Information System (INIS)

Research highlights: ? We studied a point focus Fresnel solar collector using different cavity receivers. ? The collector heat removal factors are derived to find the optimal cavity shape. ? Numerical and experimental analysis shows that the conical cavity is optimum. -- Abstract: A high concentration imaging Fresnel solar collector provided with different cavity receivers was developed and its behavior was investigated. Round copper pipes winded into different spring shapes were used as receiver by placing in the cylindrical cavity to absorb concentrated solar energy and transfer it to a heat transfer fluid (HTF). The collector efficiency factor and collector heat removal factor were derived for the cavity receivers to find out heat transfer mechanism and to propose an effective way for evaluating the performance of Fresnel solar collector and determining the optimal cavity structure. The problem of Fresnel solar collector with synthetic heat transfer oil flow was simulated and analyzed to investigate heat loss from different cavity receivers. Solar irradiation as well as convection and heat transfer in the circulating fluid and between the internal surfaces of the cavity and the environment are considered in the model. The temperature distribution over its area as well as the collector thermal efficiency at nominal flow rate was used in order to validate the simulation results. It was found that the simulated temperature distribution during operation and the atribution during operation and the average collector efficiency are in good agreement with the experimental data. Finally, the optimal shape of solar cavity receiver, as well as its thermal performance, are deeply analyzed and discussed.

388

The ``secure`` and regulatory heat of the radiant heat pipe; La chaleur ``secure`` et reglementaire du caloduc rayonnant  

Energy Technology Data Exchange (ETDEWEB)

This short note presents an innovative radiant space heating system based on the heat pipe principle (evaporation-condensation) and which combines the advantages of both systems: uncoupling of the heat source and lower radiant temperature. This system uses the gravity-assisted two-phase thermosyphon effect and is compatible with the European regulation. (J.S.)

Anon.

1998-11-01

389

Design and beam transport simulations of a multistage collector for the Israeli EA-FEM  

CERN Document Server

A four stage asymmetric type depressed collector has been designed for the Israeli mm-wave FEM that is driven by a 1.4 MeV, 1.5 A electron beam. After leaving the interaction section the spent beam has an energy spread of 120 keV and 75 pi mm mrad normalized beam emittance. Simulations of the beam transport system from the undulator exit through the decelerator tube into the collector have been carried out using EGUN and GPT codes. The latter has also been employed to study trajectories of the primary and scattered particles within the collector, optimizing the asymmetrical collector geometry and the electrode potentials at the presence of a deflecting magnetic field. The estimated overall system and collector efficiencies reach 50% and 70%, respectively, with a beam recovery of 99.6%. The design is aimed to attain millisecond long pulse operation and subsequently 1 kW average power. Simulation results are implemented in a mechanical design that leads to a simple, cost efficient assembly eliminating ceramic i...

Tecimer, M; Efimov, S; Gover, A; Sokolowski, J

2001-01-01

390

Theoretical and Experimental Analyses of Heat Transfer in a Flat-Plate Solar Collector  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, the heat transfer in a flat-plate solar collector with water tubes spreading across its width was analyzed. The performances of the system both theoretically and experimentally were evaluated and compared. The theoretical results obtained agreed well with the experimental results, except that a slight higher deviation of heat loss was obtained in the experimental analysis and low solar radiation in the morning and late afternoon affects the system. An average heat loss coefficient of 0.68 W/m2.°C was obtained in the experimental analysis, while 0.65 W/m2.°C was obtained in the theoretical analysis. The collector efficiency was high around the mid-day when the collector receives the highest energy and the useful heat rate was at its maximum. The results also reveal that the performance of the solar collector depends much on the heat rate. The collector efficiency increases as the heat rate increases until a maximum efficiency of 72.2 % was reached at optimum heat rate of 785 W.

Bukola Olalekan BOLAJI

2012-09-01

391

SOLERAS - Solar-Powered Water Desalination Project at Yanbu: Solar-collector field experimental tests  

Energy Technology Data Exchange (ETDEWEB)

The solar-collection field subsystem of the solar-powered desalination pilot project located at Yanbu in the Kingdom of Saudi Arabia has been operated successfully for two years. It has been demonstrated that during a one-year period, the solar-collector field can, on the average, provide about 2500 kWh of thermal energy a day for days with a daily insolation total greater than 4000 Wh/m/sup 2/. This is a yearlong solar-collector field average efficiency of 22.5%. In Yanbu, from October 1, 1985, until September 30, 1986, there were only 21 days (5.8%) when the daily direct-normal insolation was less than the mid-60% to 70% range with a peak output of 51 kW per solar collector. It has also been demonstrated that the Power Kinetics, Inc., square-dish solar collector has a problem due to the fixed aperture (outboard focus) that seriously hurts the performance of the solar collector during the summer months at this latitude. A location at latitudes greater than +-35/degree/ would see greatly improved daylong summer performance. 4 refs., 3 figs., 1 tab.

Zimmerman, J.C.; Al-Abbadi, N.

1987-06-01

392

Modeling and experimental validation of the solar loop for absorption solar cooling system using double-glazed collectors  

International Nuclear Information System (INIS)

Solar cooling applied to buildings is without a doubt an interesting alternative for reducing energy consumption in traditional mechanical steam compression air conditioning systems. The study of these systems should have a closely purely fundamental approach including the development of numerical models in order to predict the overall installation performance. The final objective is to estimate cooling capacity, power consumption, and overall installation performance with relation to outside factors (solar irradiation, outside temperature...). The first stage in this work consists of estimating the primary energy produced by the solar collector field. The estimation of this primary energy is crucial to ensure the evaluation of the cooling capacity and therefore the cooling distribution and thermal comfort in the building. Indeed, the absorption chiller performance is directly related to its heat source. This study presents dynamic models for double glazing solar collectors and compares the results of the simulation with experimental results taken from our test bench (two collectors). In the second part, we present an extensive collector field model (36 collectors) from our solar cooling installation at The University Institute of Technology in St Pierre, Reunion Island as well as our stratified tank storage model. A comparison of the simulation results with real scale solar experimental data taken from our installation enables validation of the double glazing solar cs validation of the double glazing solar collector and stratified tank dynamic models.

393

MERCURY CONTROL WITH ADVANCED HYBRID PARTICULATE COLLECTOR  

Energy Technology Data Exchange (ETDEWEB)

This project was awarded under U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Program Solicitation DE-PS26-00NT40769 and specifically addressed Technical Topical Area 4-Testing Novel and Less Mature Control Technologies on Actual Flue Gas at the Pilot Scale. The project team included the Energy & Environmental Research Center (EERC) as the main contractor; W.L. Gore & Associates, Inc., as a technical and financial partner; and the Big Stone Power Plant operated by Otter Tail Power Company, host for the field-testing portion of the research. Since 1995, DOE has supported development of a new concept in particulate control called the advanced hybrid particulate collector (AHPC). The AHPC has been licensed to W.L. Gore & Associates, Inc., and has been marketed as the Advanced Hybrid{trademark} filter by Gore. The Advanced Hybrid{trademark} filter combines the best features of electrostatic precipitators (ESPs) and baghouses in a unique configuration, providing major synergism between the two collection methods, both in the particulate collection step and in the transfer of dust to the hopper. The Advanced Hybrid{trademark} filter provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emissions with conventional ESPs, and it solves the problem of reentrainment and re-collection of dust in conventional baghouses. The Advanced Hybrid{trademark} filter also appears to have unique advantages for mercury control over baghouses or ESPs as an excellent gas--solid contactor. The objective of the project was to demonstrate 90% total mercury control in the Advanced Hybrid{trademark} filter at a lower cost than current mercury control estimates. The approach included bench-scale batch tests, larger-scale pilot testing with real flue gas on a coal-fired combustion system, and field demonstration at the 2.5-MW (9000-acfm) scale at a utility power plant to prove scale-up and demonstrate longer-term mercury control. An additional task was included in this project to evaluate mercury oxidation upstream of a dry scrubber by using mercury oxidants. This project demonstrated at the pilot-scale level a technology that provides a cost-effective technique to control mercury and, at the same time, greatly enhances fine particulate collection efficiency. The technology can be used to retrofit systems currently employing inefficient ESP technology as well as for new construction, thereby providing a solution for improved fine particulate control combined with effective mercury control for a large segment of the U.S. utility industry as well as other industries.

Ye Zhuang; Stanley J. Miller

2005-05-01

394

Effect of beam limiting aperture and collector potential on multi-element focused ion beams  

Energy Technology Data Exchange (ETDEWEB)

A compact microwave driven plasma based multi-element focused ion beam system has been developed. In the present work, the effect of reduced beam limiter (BL) aperture on the focused ion beam parameters, such as current and spot size, and a method of controlling beam energy independently by introducing a biased collector at focal point (FP) are investigated. It is found that the location of FP does not change due to the reduction of BL aperture. The location of FP and beam size are found to be weakly dependent on the collector potential in the range from -8 kV to -18 kV.

Paul, Samit; Chowdhury, Abhishek; Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur, Uttar Pradesh (India)

2012-02-15

395

Rapid separation of isobars with use of collector of ISOL facilities  

International Nuclear Information System (INIS)

Volatility of Rb, Sr, Y, Ba some of rare earth elements, Ra, Ac, Th, implanted in a tantalum collector with the energy of 45 keV is investigated. The collector heating for 180 s in vacuum results in separation of the implanted elements. Separation coefficients under the conditions constitute: asub(Sr/Rb)=14 (1390 K), asub(Y/Sr)=28 (1680 K), asub(La/Ba)=8 (1590 K), asub(Sm/Eu)=3 (1470 K), asub(Gd/Eu)=22 (1620 K), asub(Tm/Yb)=8 (1600K), asub(Lu/Yb)=38 (1700 K) and asub(Ac/Ra)=asub(Th/Ra)=30 (1650 K). Contributions made by diffusion and desorption to volatility of the implanted elements and prospects of usage of the technique suggested to separate isobars with an aid of collector of ISOL facilities are discussed

396

A prototype photovoltaic/thermal system integrated with transpired collector  

Energy Technology Data Exchange (ETDEWEB)

Building-integrated photovoltaic/thermal (BIPV/T) systems may be utilized to produce useful heat while simultaneously generating electricity from the same building envelope surface. A well known highly efficient collector is the open-loop unglazed transpired collector (UTC) which consists of dark porous cladding through which outdoor air is drawn and heated by absorbed solar radiation. Commercially available photovoltaic systems typically produce electricity with efficiencies up to about 18%. Thus, it is beneficial to obtain much of the normally wasted heat from the systems, possibly by combining UTC with photovoltaics. Combination of BIPV/T and UTC systems for building facades is considered in this paper - specifically, the design of a prototype facade-integrated photovoltaic/thermal system with transpired collector (BIPV/T). A full scale prototype is constructed with 70% of UTC area covered with PV modules specially designed to enhance heat recovery and compared to a UTC of the same area under outdoor sunny conditions with low wind. The orientation of the corrugations in the UTC is horizontal and the black-framed modules are attached so as to facilitate flow into the UTC plenum. While the overall combined thermal efficiency of the UTC is higher than that of the BIPV/T system, the value of the generated energy - assuming that electricity is at least four times more valuable than heat - is between 7% and 17% higher. Also, the electricity is always useful while the heat is usually utilized only in the heating season. The BIPV/T concept is applied to a full scale office building demonstration project in Montreal, Canada. The ratio of photovoltaic area coverage of the UTC may be selected based on the fresh air heating needs of the building, the value of the electricity generated and the available building surfaces. (author)

Athienitis, Andreas K.; Bambara, James; O' Neill, Brendan; Faille, Jonathan [Dept. of Building, Civil and Environmental Engineering, Concordia University, 1455 Maisonneuve W., Montreal, Quebec (Canada)

2011-01-15

397

Grid collector: An event catalog with automated file management  

International Nuclear Information System (INIS)

High Energy Nuclear Physics (HENP) experiments such as STAR at BNL and ATLAS at CERN produce large amounts of data that are stored as files on mass storage systems in computer centers. In these files, the basic unit of data is an event. Analysis is typically performed on a selected set of events. The files containing these events have to be located, copied from mass storage systems to disks before analysis, and removed when no longer needed. These file management tasks are tedious and time consuming. Typically, all events contained in the files are read into memory before a selection is made. Since the time to read the events dominate the overall execution time, reading the unwanted event needlessly increases the analysis time. The Grid Collector is a set of software modules that works together to address these two issues. It automates the file management tasks and provides ''direct'' access to the selected events for analyses. It is currently integrated with the STAR analysis framework. The users can select events based on tags, such as, ''production date between March 10 and 20, and the number of charged tracks > 100.'' The Grid Collector locates the files containing relevant events, transfers the files across the Grid if necessary, and delivers the events to the analysis code through the familiar iterators. There has been some research efforts to address the file management issues, the Grid Collector is unique in that it addresses the event access issue together with the file management issues. This makes it more useful to a large variety of users

398

Thermal performance of honeywell double covered liquid solar collector  

Science.gov (United States)

The test procedures and results obtained during an evaluation test program to determine the outdoor performance characteristics of the Honeywell liquid solar collector are presented. The program was based on the thermal evaluation of a Honeywell double covered liquid solar collection. Initial plans included the simultaneous testing of a single covered Honeywell collector. During the initial testing, the single covered collector failed due to leakage; thus, testing continued on the double covered collector only. To better define the operating characteristics of the collector, several additional data points were obtained beyond those requested.

Losey, R.

1977-01-01

399

Testing and analysis of a heat-pipe solar collector  

Science.gov (United States)

The development of an integral heat-pipe/evacuated-tube solar collector in which the inner receiver tubes form the evaporator sections of glass heat pipes is reported. This paper describes both theoretical analyses and empirical tests, comparing the performance of the glass-heat-pipe solar collector with that of a high-efficiency evacuated-tube solar collector. The comparison demonstrates that the performance of the two collectors is effectively identical. The testing and analysis indicate that the glass-wick-type glass heat pipe is an effective heat-transfer system for evacuated-tube solar collectors.

Ribot, J.; McConnell, R. D.

1983-11-01

400

Parabolic Trough Photovoltaic/Thermal Collectors: Design and Simulation Model  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a design procedure and a simulation model of a novel concentrating PVT collector. The layout of the PVT system under investigation was derived from a prototype recently presented in literature and commercially available. The prototype consisted in a parabolic trough concentrator and a linear triangular receiver. In that prototype, the bottom surfaces of the receiver are equipped with mono-crystalline silicon cells whereas the top surface is covered by an absorbing surface. The aperture area of the parabola was covered by a glass in order to improve the thermal efficiency of the system. In the modified version of the collector considered in this paper, two changes are implemented: the cover glass was eliminated and the mono-crystalline silicon cells were replaced by triple-junction cells. In order to analyze PVT performance, a detailed mathematical model was implemented. This model is based on zero-dimensional energy balances. The simulation model calculates the temperatures of the main components of the system and the main energy flows Results showed that the performance of the system is excellent even when the fluid temperature is very high (>100 °C. Conversely, both electrical and thermal efficiencies dramatically decrease when the incident beam radiation decreases.

Laura Vanoli

2012-10-01

401

Theoretical and experimental analysis and optimization of semi-transparent solar thermal façade collectors  

OpenAIRE

This thesis presents three models for transparent façade components: a detailed physical model including a sophisticated optical simulation, a simplified model for transparent façade components and a black-box model for passive façades. The models are validated by extensive measurements and used for whole-year simulations to estimate the primary energy savings of transparent solar thermal façade collectors.

Maurer, Christoph

2012-01-01

402

Integrated Design of Undepressed Collector for Low Power Gyrotron  

Science.gov (United States)

A 42 GHz, 200 kW continuous wave (CW) gyrotron, operating at TE03 mode is under development for the electron cyclotron resonance plasma heating of the Indian TOKAMAK system. The gyrotron is made up of an undepressed collector. The undepressed collector is simple to design and cost effective. In this paper, a detailed design study of the undepressed collector for the 42 GHz gyrotron is presented. The EGUN code is used to analyze the spent electron beam trajectory for the maximum spread to reduce the power loading on the collector surface. To achieve wall loading ?1 kW/cm2, a collector with a length of 800 mm and a radius of 42.5 mm is designed. The design also includes the three magnet systems around the collector for maximum and uniform beam spread. The thermal and the structural analyses are done using the ANSYS code to optimize the collector structure and dimensions with tolerance.

Kumar, Anil; Goswami, Uttam K.; Poonia, Sunita; Singh, Udaybir; Kumar, Nitin; Alaria, M. K.; Bera, A.; Khatun, Hasina; Sinha, A. K.

2011-06-01

403

Theoretical study on a solar collector loop during stagnation  

DEFF Research Database (Denmark)

A mathematical model simulating the stagnation behavior of a pressurized solar collector loop with solar collectors with a good emptying behavior is developed. Based on the pre-pressure of the expansion vessel, the system filling pressure of the solar collector loop and the design of the solar collector loop, the mass of the fluid flowing into the pressurized expansion vessel and the pressures at the top part and at the bottom part of the solar collector loop during stagnation for the solar collector loop are calculated. The theoretically calculated results are compared with experimental results. There is a good agreement between calculations and measurements. The developed simulation model is therefore suitable to determine the behavior of solar collector loops during stagnation.

Chen, Ziqian; Dragsted, Janne

2010-01-01

404

Selective spectral filtration with nanoparticles for concentrating solar collectors  

Science.gov (United States)

A spectral fluid filter for potential use in hybrid photovoltaic/thermal concentrating solar collectors has been developed, targeting maximum absorption above and transmission below a desired wavelength. In this application, the temperature-dependent bandgap of the potential solar cell is used in the optimization of the filter. Dispersing a mix of colloidal nanoparticles in a heat transfer fluid is shown to absorb 86% of sub-bandgap insolation while absorbing only 18% above bandgap insolation. Transmission above bandgap light would be directly absorbed into the photovoltaic (PV) cell while absorbed photons transfer energy directly into the heat transfer fluid ultimately reducing the number of heat transfer steps. Placement of a filter in front of the PV cell is shown to decrease losses by converting an additional 2% of the total solar energy into thermal energy since it allows recollection of light reflected off the receiver.

DeJarnette, Drew; Otanicar, Todd; Brekke, Nick; Hari, Parameswar; Roberts, Kenneth

2015-01-01

405

Thermal Conditions in a Simulated Office Environment with Convective and Radiant Cooling Systems  

DEFF Research Database (Denmark)

The thermal conditions in a two person office room were measured with four air conditioning systems: chilled beam (CB), chilled beam with radiant panel (CBR), chilled ceiling with ceiling installed mixing ventilation (CCMV) and four desk partition mounted local radiant cooling panels with mixing ventilation (MVRC). CB was based on convection cooling while the remaining three systems (CBR, CCMV and MVRC) on combined radiant and convective cooling. Measurements were performed in design (64 W/m2) and usual (38 W/m2) cooling conditions. Air temperature, operative temperature, radiant asymmetry, air velocity and turbulent intensity were measured and draft rate levels calculated in the room. Manikin-based equivalent temperature (MBET) was determined by two thermal manikins to identify the impact of the local thermal conditions generated by the studied systems on occupants’ thermal comfort. The results revealed that the differences in thermal conditions between the four systems were not significant. This result was contrary to the expectation that operative temperature would be lower in the CCMV case. The velocity levels in the occupied zone were slightly higher in both CB and CBR cases. However the highest measured values were located outside the workstations.

Mustakallio, Panu; Bolashikov, Zhecho Dimitrov

2013-01-01

406

Calculation codes for radiant heat transfers; Les codes de calcul de rayonnement thermique  

Energy Technology Data Exchange (ETDEWEB)

This document reports on 12 papers about computerized simulation and modeling of radiant heat transfers and fluid flows in various industrial and domestic situations: space heating, metal industry (furnaces, boilers..), aerospace industry (turbojet engines, combustion chambers) etc.. This workshop was organized by the ``radiation`` section of the French society of thermal engineers. (J.S.)

NONE

1996-12-31

407

Evaluation of Test Method for Solar Collector Efficiency  

DEFF Research Database (Denmark)

The test method of the standard EN12975-2 (European Committee for Standardization, 2004) is used by European test laboratories to determine the efficiency of solar collectors. In the test methods the mean solar collector fluid temperature in the solar collector, Tm is determined by the approximated equation where Tin is the inlet temperature to the collector and Tout is the outlet temperature from the collector. The specific heat of the solar collector fluid is in the test method as an approximation determined as a constant equal to the specific heat of the solar collector fluid at the temperature Tm. The power produced by the solar collector during a test period is determined by the product of the specific heat, the mass flow rate and the temperature increase of the solar collector fluid. The solar collector efficiency is in the standard determined by measurements at different temperature levels. Based on these efficiencies, an efficiency equation is determined by regression analysis. In the test method, there are no requirements on the ambient air temperature and the sky temperature. The paper will present an evaluation of the test method for a 12.5 m² flat plate solar collector panel from Arcon Solvarme A/S. The solar collector panel investigated has 16 parallel connected horizontal absorber fins. CFD (Computational Fluid Dynamics) simulations, calculations with a solar collector simulation program SOLEFF (Rasmussen and Svendsen, 1996) and thermal experiments are carried out in the investigation. The investigations elucidate: • How the mean solar collector fluid temperature Tm is underestimated by the approximated equation in the test standard and how the collector efficiency equation is influenced by the underestimation of Tm. The dependence of the volume flow rate is shown; • How the use of the approximated specific heat of the solar collector fluid is influencing the collector efficiency expression; • How the temperature levels used is influencing the collector efficiency expression; • How the measured collector efficiency is influenced by the weather conditions such as the ambient air temperature and the sky temperature. Based on the investigations, recommendations for change of the test methods and test conditions are considered. The investigations are carried out within the NEGST (New Generation of Solar Thermal Systems) project financed by EU.

Fan, Jianhua; Shah, Louise Jivan

408

Local configuration factors for radiant interchange between cylindrical surfaces in rod bundle geometry  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: We have obtained view factor values for ring elements of nuclear fuel rod bundle. The simplest, effective and accurate contour integral method is adopted for this analysis. View factor values for the interference rod case is a distinct feature of this article. Analytical expressions helps finding configuration factor values elapsing less computational time. - Abstract: The aim of this study is to obtain configuration factor expressions for the diffuse interchange of radiant energy between two parallel cylindrical rods by contour integral technique. The contour integral approach for diffuse configuration factors has been derived by . It replaces the usual area integrals by more tractable contour (i.e., line) integrals, which simplifies analytical calculation of configuration factors. The advantages of this representation are associated with the reduced order of the integrals (i.e., double reduced to single, quadruple reduced to double) which must be evaluated to calculate the angle factor. For the numerical or analytical evaluation of configuration factors, the reduction in the order of the integrals has a great practical utility. In the literature, contour integral technique has been stated to appreciably be the more precise method than the area integration method. The cases studied are for elemental ring areas of (i) two cylindrical rods/tubes, (ii) two cylindrical rods with interference from a third rod and (iii) cylindrical rod within a cylindrical enclosure. The results of present configuration factor expressions meant for the ring elements of finite length geometries have been compared with values using exact algebraic expressions available in the literature for infinite length, analytical configuration factor expressions for equal finite lengths and with numerical results available in the literature. Contour integral technique has been observed to be a simple method that yields realistic results. This study has application in the analysis of fin-tube radiators, boiler tubes, nuclear fuel rod bundle, etc.

Bopche, Santosh B., E-mail: santoshb.bopche@yahoo.co.i [Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India); Sridharan, Arunkumar, E-mail: arunsri15@gmail.co [Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India)

2011-03-15

409

Comparison and analysis on test methods of infrared radiant intensity of infrared decoy  

Science.gov (United States)

The research on infrared radiant characteristics of typical target is important for the detection and recognition of target, infrared simulation calculation and design of electro-optical countermeasures. Thus it is essential to select appropriate test method and optimal calculation method to improve the test accuracy and reliability of infrared radiant intensity. In this paper, three instruments including SR5000 spectroradiometer (CI, MigdalHaEmek, Israel), remote sensing interferometer spectrometer Tensor37 (Bruker, Germany) and Image IR8325 (InfraTec Ltd, Germany) mid-infrared thermal imager were applied to test the infrared radiant (1?m-3?m - 3?m-5?m) intensity of decoy samples. Three methods were designed based on two operational principles including direct test and indirect test. The SR5000 spectroradiometer which is able to obtain the value of radian intensity immediately is regard as direct test. The other two instruments which deduce and calculate infrared radiant intensity according to Planck's law and Lambert's cosine law with some preliminary tested parameters such as the response voltage - the distribution of infrared radiant temperature of flaming samples and calibrated data by blackbody, however, are regard as indirect test. Reasons for the diversity of experiment results were provided through analysis on the concrete measurement theory and detailed calculation methods. Moreover, some rules and suggestions were put forward to improve the test accuracy and reliability of infrared radiant intensity when different methods were adopted. It is shown from experiment results that the average mid-infrared radiant intensity obtained from SR5000 was about 903W/Sr in near-infrared band - whereas Tensor 37 and Image IR8325 was about 834W/Sr and 547 W/Sr respectively. It was proved that maximum relative of calculated results from remote sensing interferometer spectrometer Tensor37 and results measured with SR5000 spectroradiometer is below 13%, which meet the general accuracy requirements. Although rigorous reasoning applied, results gained by Image IR8325 mid-infrared thermal imager varied so much from above-mentioned two instruments and the relative error is about 25%~40%. It is analyzed that complexity of the measurement procedure and similarity hypothesis is the main reason for the errors generated.

Chen, Chunsheng; Dai, Mengyan; Liu, Haifeng; Fang, Guofeng; Xie, Changyou; Zhang, Tong

2014-11-01

410

Radiant heat loss, an unexploited path for heat stress reduction in shaded cattle.  

Science.gov (United States)

Reducing thermal radiation on shaded animals reduces heat stress independently of other means of stress relief. Radiant heat exchange was estimated as a function of climate, shade structure, and animal density. Body surface portion exposed to radiant sources in shaded environments was determined by geometrical relations to determine angles of view of radiation sources (roof underside, sky, sun-exposed ground, shaded ground) on the animal's surface. The relative representation of environment radiation sources on the body surface was determined. Animal thermal radiation balance was derived from radiant heat gained from radiation sources (including surrounding animals) and that lost from the animal surface. The animal environment was assumed to have different shade dimensions and temperatures. These were summed to the radiant heat balance of the cow. The data formed served to estimate the effect of changes in intensity of radiation sources, roof and shaded surface dimensions, and animal density on radiant heat balance (Rbal) of cattle. Roof height effect was expressed by effect of roof temperature on Rbal. Roof underside temperature (35 to 75°C) effect on Rbal was reduced by roof height. If roof height were 4m, an increase in its underside temperature from 35 to 75°C would increase mean Rbal from -63 to -2 W·m?², whereas if roof height were 10 m, Rbal would only increase from -99 to -88 W·m?². A hot ground temperature increase from 35 to 65°C reduced mean Rbal heat loss from -45 to 3 W·m?². Increasing the surface of the shaded area had only a minor effect on Rbal and on the effect of hot ground on Rbal. Increasing shade roof height reduced the effect of roof temperature on Rbal to minor levels when height was > 8m. Increasing the roof height from 4 to 10 m decreased Rbal from -32 to -94 W·m?². Increasing indirect radiation from 100 to 500 W·m?² was associated with an increase in Rbal from -135 to +23 W·m?². Their combined effects were lower Rbal with increasing roof height and a reduction in rate of decrease with increasing level of indirect radiation. Roof height as an Rbal attenuator declined with increasing indirect radiation level. The latter factor might be reduced by lowering roof surface radiation absorption and through roof heat transfer, as well as by use of shade structure elements to reduce indirect radiation in the shaded area. Radiant heat from the cow body surface may be reduced by lower cow density. Radiant heat attenuation may thus further elevate animal productivity in warm climates, with no associated operation costs. PMID:22612938

Berman, A; Horovitz, T

2012-06-01

411

Thermal and hydraulic analysis of multilayered asphalt pavements as active solar collectors  

International Nuclear Information System (INIS)

Highlights: • A new type of asphalt solar collector has been introduced in this paper. • The common pipe network has been replaced for a highly porous asphalt layer. • The use of these collectors contributes to achieve current environmental targets. • Excellent thermal efficiencies have been obtained in the laboratory tests. • Further research is needed to increase the low flow rates achieved. - Abstract: The fulfillment of current environmental aims like reducing fossil fuel consumption or greenhouse gas emissions entails the development of new technologies that enable the use of cleaner, cheaper and renewable energies. Furthermore, the need to improve energy efficiency in buildings encourages scientists and engineers to find new ways of harvesting energy for later uses. The use of asphalt pavements as active solar collectors is introduced in this article. Several authors have studied the use of roads as an energy source before. However, a new technology is presented in which a multilayered pavement with a highly porous middle layer is used instead of a solar collector with an embedded pipe network. These collectors are fully integrated within the road infrastructure and may offer low cost solar energy for water heating. The paper includes a brief comment on the state-of-the-art. Then, a broad methodology is presented in which data, materials and procedures needed to run the tests are fully described. Finally, the results of the laboratory tests are stated and discussed. The prototype used in the laboratory provided excellent thermal efficiency. However, these good results contrast with the low flow rate levels registered during the tests. Thus, although this technology seems to be very promising, new experimental tests should be performed before an effective application is possible

412

A hybrid air conditioner driven by a hybrid solar collector  

Science.gov (United States)

The objective of this thesis is to search for an efficient way of utilizing solar energy in air conditioning applications. The current solar Air Conditioners (A/C)s suffer from low Coefficient of Performance (COP) and performance degradation in hot and humid climates. By investigating the possible ways of utilizing solar energy in air conditioning applications, the bottlenecks in these approaches were identified. That resulted in proposing a novel system whose subsystem synergy led to a COP higher than unity. The proposed system was found to maintain indoor comfort at a higher COP compared to the most common solar A/Cs, especially under very hot and humid climate conditions. The novelty of the proposed A/C is to use a concentrating photovoltaic/thermal collector, which outputs thermal and electrical energy simultaneously, to drive a hybrid A/C. The performance of the hybrid A/C, which consists of a desiccant wheel, an enthalpy wheel, and a vapor compression cycle (VCC), was investigated experimentally. This work also explored the use of a new type of desiccant material, which can be regenerated with a low temperature heat source. The experimental results showed that the hybrid A/C is more effective than the standalone VCC in maintaining the indoor conditions within the comfort zone. Using the experimental data, the COP of the hybrid A/C driven by a hybrid solar collector was found to be at least double that of the current solar A/Cs. The innovative integration of its subsystems allows each subsystem to do what it can do best. That leads to lower energy consumption which helps reduce the peak electrical loads on electric utilities and reduces the consumer operating cost since less energy is purchased during the on peak periods and less solar collector area is needed. In order for the proposed A/C to become a real alternative to conventional systems, its performance and total cost were optimized using the experimentally validated model. The results showed that for an electricity price of 0.12 $/kW-hr, the hybrid solar A/C's cumulative total cost will be less than that of a standard VCC after 17.5 years of operation.

Al-Alili, Ali