WorldWideScience

Sample records for radiant energy collector

  1. Multiscale computational modeling of a radiantly driven solar thermal collector

    Science.gov (United States)

    Ponnuru, Koushik

    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.

  2. Tower-supported solar-energy collector

    Science.gov (United States)

    Selcuk, M. K.

    1977-01-01

    Multiple-collector tower system supports three receiver/concentrators that absorb solar energy reflected from surrounding field of heliostats. System overcomes disadvantages of tower-supported collectors. Booms can be lowered during heavy winds to protect arms and collectors.

  3. Flatplate Solar Energy Collector

    Science.gov (United States)

    1976-01-01

    A small truck body fabricator in Florida became producer of flatplate solar collectors after having an inexpensive literature search performed by the NASA IAC in Research Triangle Park, NC. The center provided him with 314 abstracts of which he requested 15 full length articles. His total cost, $100.00, was sufficient to launch his new venture OEM Products, Inc. Flatplate collector design incorporates new black paint developed by Dow-Corning Corporation but not yet commercially available.

  4. Thin film solar energy collector

    Science.gov (United States)

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

    1983-11-22

    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.

  5. Clouds and the Earth's Radiant Energy System (CERES)

    Data.gov (United States)

    National Aeronautics and Space Administration — The Clouds and the Earth's Radiant Energy System (CERES) is a key component of the Earth Observing System (EOS) program. The CERES instruments provide radiometric...

  6. Radiant energy required for infrared neural stimulation.

    Science.gov (United States)

    Tan, Xiaodong; Rajguru, Suhrud; Young, Hunter; Xia, Nan; Stock, Stuart R; Xiao, Xianghui; Richter, Claus-Peter

    2015-01-01

    Infrared neural stimulation (INS) has been proposed as an alternative method to electrical stimulation because of its spatial selective stimulation. Independent of the mechanism for INS, to translate the method into a device it is important to determine the energy for stimulation required at the target structure. Custom-designed, flat and angle polished fibers, were used to deliver the photons. By rotating the angle polished fibers, the orientation of the radiation beam in the cochlea could be changed. INS-evoked compound action potentials and single unit responses in the central nucleus of the inferior colliculus (ICC) were recorded. X-ray computed tomography was used to determine the orientation of the optical fiber. Maximum responses were observed when the radiation beam was directed towards the spiral ganglion neurons (SGNs), whereas little responses were seen when the beam was directed towards the basilar membrane. The radiant exposure required at the SGNs to evoke compound action potentials (CAPs) or ICC responses was on average 18.9?±?12.2 or 10.3?±?4.9?mJ/cm(2), respectively. For cochlear INS it has been debated whether the radiation directly stimulates the SGNs or evokes a photoacoustic effect. The results support the view that a direct interaction between neurons and radiation dominates the response to INS. PMID:26305106

  7. Combined solar collector and energy storage system

    Science.gov (United States)

    Jensen, R. N. (inventor)

    1980-01-01

    A combined solar energy collector, fluid chiller and energy storage system is disclosed. A movable interior insulated panel in a storage tank is positionable flush against the storage tank wall to insulate the tank for energy storage. The movable interior insulated panel is alternately positionable to form a solar collector or fluid chiller through which the fluid flows by natural circulation.

  8. Radiant Barriers Save Energy in Buildings

    Science.gov (United States)

    2014-01-01

    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.

  9. Radiant energy during infrared neural stimulation at the target structure

    OpenAIRE

    Richter, Claus-Peter; Rajguru, Suhrud; Stafford, Ryan; Stock, Stuart R.

    2013-01-01

    Infrared neural stimulation (INS) describes a method, by which an infrared laser is used to stimulate neurons. The major benefit of INS over stimulating neurons with electrical current is its spatial selectivity. To translate the technique into a clinical application it is important to know the energy required to stimulate the neural structure. With this study we provide measurements of the radiant exposure, at the target structure that is required to stimulate the auditory neurons. Flat poli...

  10. Effect of Radiant Energy on Near-Surface Water

    Science.gov (United States)

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

    2010-01-01

    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

  11. Radiant energy during infrared neural stimulation at the target structure.

    Science.gov (United States)

    Richter, Claus-Peter; Rajguru, Suhrud; Stafford, Ryan; Stock, Stuart R

    2013-03-01

    Infrared neural stimulation (INS) describes a method, by which an infrared laser is used to stimulate neurons. The major benefit of INS over stimulating neurons with electrical current is its spatial selectivity. To translate the technique into a clinical application it is important to know the energy required to stimulate the neural structure. With this study we provide measurements of the radiant exposure, at the target structure that is required to stimulate the auditory neurons. Flat polished fibers were inserted into scala tympani so that the spiral ganglion was in front of the optical fiber. Angle polished fibers were inserted along scala tympani, and rotating the beveled surface of the fiber allowed the radiation beam to be directed perpendicular to the spiral ganglion. The radiant exposure for stimulation at the modiolus for flat and angle polished fibers averaged 6.78±2.15 mJ/cm(2). With the angle polished fibers, a 90° change in the orientation of the optical beam from an orientation that resulted in an INS-evoked maximum response, resulted in a 50% drop in the response amplitude. When the orientation of the beam was changed by 180°, such that it was directed opposite to the orientation with the maxima, minimum response amplitude was observed. PMID:25075261

  12. Adaptive control of solar energy collector systems

    CERN Document Server

    Lemos, João M; Igreja, José M

    2014-01-01

    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

  13. Numerical modelling the unsteady process of closed rectangular area radiant heating in conjugate formulation with accounting energy distribution along horizontal and vertical enclosure structures

    Science.gov (United States)

    Nee, A. E.

    2014-08-01

    Mathematical modelling of unsteady convective-conductive heat exchange in premises, heated by infrared radiant heater is passed. Heat flux density from infrared radiant heater was calculated accounting energy distribution along horizontal and vertical building envelope. Comparison between zonal method and Lambert's law radiant energy distribution was done.

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

    OpenAIRE

    Qing Zhao; Pollack, Gerald H; Xavier Figueroa

    2009-01-01

    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 the...

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

    Directory of Open Access Journals (Sweden)

    Qing Zhao

    2009-03-01

    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.

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

    Science.gov (United States)

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

    2009-01-01

    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

  17. Particle Displacement in Aqueous Suspension Arising from Incident Radiant Energy.

    Science.gov (United States)

    Kimura, Kevin W; Pollack, Gerald H

    2015-09-29

    Colloidal particles in aqueous suspension generally sediment uniformly. By contrast, we found that suspensions of latex microspheres in polystyrene Petri dishes deviated sharply from the expected pattern when various objects were positioned immediately outside those dishes. When small coin-like metal discs were positioned immediately beneath the Petri dish, the microspheres sedimented to a point just above those discs. Other materials, including glass and wood, produced similar results, though less pronounced. After the microspheres had sedimented, shifting the metal to another position beneath the dish caused the microspheres to follow. Various control experiments ruled out trivial explanations. In concordance with earlier results, it appears that the infrared energy generated by the various materials draws microspheres, resulting in the unusual sedimentation patterns. The results have significant implications for the mechanism of sedimentation, particularly for the role of charge in that process. PMID:26335979

  18. Clouds and the Earth's Radiant Energy System (CERES) Visualization Single Satellite Footprint (SSF) Plot Generator

    Science.gov (United States)

    Barsi, Julia A.

    1995-01-01

    The first Clouds and the Earth's Radiant Energy System (CERES) instrument will be launched in 1997 to collect data on the Earth's radiation budget. The data retrieved from the satellite will be processed through twelve subsystems. The Single Satellite Footprint (SSF) plot generator software was written to assist scientists in the early stages of CERES data analysis, producing two-dimensional plots of the footprint radiation and cloud data generated by one of the subsystems. Until the satellite is launched, however, software developers need verification tools to check their code. This plot generator will aid programmers by geolocating algorithm result on a global map.

  19. 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)

  20. Energy flow and thermal comfort in buildings: Comparison of radiant and air-based heating & cooling systems : Revised version

    DEFF Research Database (Denmark)

    Le Dréau, Jérôme

    2014-01-01

    Heating and cooling terminals can be classified in two main categories: convective terminals (e.g air conditioning, active chilled beam, fan coil) and radiant terminals. The two terminals have different modes of heat transfer: the first one is mainly based on convection, whereas the second one is based on both radiation and convection. This thesis focuses on characterizing the heat transfer from the terminal towards the space and on the parameters influencing the effectiveness of terminals. Therefore the comfort conditions and energy consumption of four types of terminals (active chilled beam, radiant floor, wall and ceiling) have been compared for a typical office room, both numerically and experimentally. From the steady-state numerical analysis and the full-scale experiments, it has been observed that the difference between the two types of terminals is mainly due to changes in the ventilation losses (or gains). At low air-change rates (below 0.5 ACH), radiant and air-based terminals have similar energy needs. For higher air change rate, the energy consumption of radiant terminals is lower than that of air-based terminals due to the higher air temperature. At 2 ACH, the energy savings of a radiant wall can be estimated to around 10% compared to the active chilled beam (in terms of delivered energy). The asymmetry between air and radiant temperature, the air temperature gradient and the possible short-circuit between inlet and outlet all play a role equally important in decreasing the cooling need of the radiant wall compared to the active chilled beam. These conclusions are valid for multi-storey and/or highly insulated buildings (R > 5 m2.K/W). In case of single-storey building with a low level of insulation, the effectiveness of radiant terminals is lower due to the larger back losses, and an air-based terminal might be more energy-efficient than a radiant terminal (in terms of delivered energy). Regarding comfort, a similar global level has been observed for the radiant and air-based terminals in both numerical and experimental investigations. But the different terminals did not achieve the same uniformity in space. The active chilled beam theoretically achieves the most uniform comfort conditions (when disregarding the risk of draught), followed by the radiant ceiling. The least uniform conditions were obtained with the cooled floor due to large differences between the sitting and standing positions. Besides this comparative study of different terminals, the relation between cooling system and internal convective flow has also been investigated experimentally. The comparison with existing models pointed out the specificity of existing correlations and the limitation of their range of application. Because of differences in the air jet trajectory, existing correlations tend to overestimate the convective flow, especially at the ceiling. Two approaches have thus been tested to better account for the air flow pattern in the definition of convective heat transfer coefficients (CHTC). In a first method, local values of air velocity have been used to evaluate convection at the ceiling. An alternative approach consists of including a modified Archimedes number in the definition of CHTC. Both methods improved the modelling of CHTC with an error around ± 15-17%.

  1. 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

  2. Energy, economic and environmental analysis of metal oxides nanofluid for flat-plate solar collector

    International Nuclear Information System (INIS)

    Highlights: • By using nanofluid, smaller and compact solar collector can be produced. • The average value of 220 MJ embodied energy can be saved. • The payback period of using nanofluid solar collector is around 2.4 years. • Around 170 kg less CO2 emissions in average for nanofluid solar collector. • Environmental damage cost is lower with the nanofluid based solar collector. - Abstract: For a solar thermal system, increasing the heat transfer area can increase the output temperature of the system. However, this approach leads to a bigger and bulkier collector. It will then increase the cost and energy needed to manufacture the solar collector. This study is carried out to estimate the potential to design a smaller solar collector that can produce the same desired output temperature. This is possible by using nanofluid as working fluid. By using numerical methods and data from literatures, efficiency, size reduction, cost and embodied energy savings are calculated for various nanofluids. From the study, it was estimated that 10,239 kg, 8625 kg, 8857 kg and 8618 kg total weight for 1000 units of solar collectors can be saved for CuO, SiO2, TiO2 and Al2O3 nanofluid respectively. The average value of 220 MJ embodied energy can be saved for each collector, 2.4 years payback period can be achieved and around 170 kg less CO2 emissions in average can be offset for the nanofluid based solar collector compared to a conventional solar collector. Finally, the environmental damage cost can also be reduced with the nanofluid based solar collector

  3. Low temperature desalination using solar collectors augmented by thermal energy storage

    International Nuclear Information System (INIS)

    Highlights: ? A new low temperature desalination process using solar collectors was investigated. ? A thermal energy storage tank (TES) was included for continuous process operation. ? Solar collector area and TES volumes were optimized by theoretical simulations. ? Economic analysis for the entire process was compared with and without TES tank. ? Energy and emission payback periods for the solar collector system were reported. -- Abstract: A low temperature desalination process capable of producing 100 L/d freshwater was designed to utilize solar energy harvested from flat plate solar collectors. Since solar insolation is intermittent, a thermal energy storage system was incorporated to run the desalination process round the clock. The requirements for solar collector area as well as thermal energy storage volume were estimated based on the variations in solar insolation. Results from this theoretical study confirm that thermal energy storage is a useful component of the system for conserving thermal energy to meet the energy demand when direct solar energy resource is not available. Thermodynamic advantages of the low temperature desalination using thermal energy storage, as well as energy and environmental emissions payback period of the system powered by flat plate solar collectors are presented. It has been determined that a solar collector area of 18 m2 with a thermal energy storage volume of 3 m3 is adequate to produce 100 L/d of freshwater round the clock considering fluctuations in the weather conditions. An economic analysis on the desalination system with thermal energy storage is also presented.

  4. Application of glass technology to novel solar energy collectors

    Energy Technology Data Exchange (ETDEWEB)

    Reed, K A

    1979-01-01

    Various compound parabolic concentrator (CPC) configurations are discussed, and the application of glass technology to CPC designs is discussed. CPC designs with flat absorbers, cylindrical absorbers, evacuated receivers, and evacuated tube receivers are considered. Also a floodlamp collector concept and a fluorescent tube collector concept are discussed. (WHK)

  5. Improvements in Clouds and the Earth's Radiant Energy System (CERES) Products Based on Instrument Calibrations

    Science.gov (United States)

    Smith, N. M.; Priestley, K.; Loeb, N. G.; Thomas, S.; Shankar, M.; Walikainen, D.

    2014-12-01

    The Clouds and the Earth's Radiant Energy System (CERES) mission is instrumental in providing highly accurate radiance measurements that are critical for monitoring the Earth's radiation budget. Two identical CERES instruments are deployed aboard NASA's Earth Observing System (EOS) satellites Terra and Aqua. Each CERES instrument consists of scanning thermistor bolometer sensors that measure broadband radiances in the shortwave (0.3 to 5 micron), total (0.3 to RAP) scan mode. Cross-track scanning, the primary mode of CERES operation, allows for the geographical mapping of the radiation fields while RAP scanning enables the acquisition of data over a more extensive combination of viewing configurations, needed for developing vastly improved angular distribution models used in radiance to flux conversion. To evaluate, achieve and maintain radiometric stability, a rigorous and comprehensive radiometric calibration and validation protocol is implemented. Calibrations and validation studies have indicated spectral changes in the reflected solar spectral regions of the shortwave and total sensors. Spectral darkening is detected in the shortwave channel optics, which is more prominent while the instrument operates in RAP mode. In the absence of a climatological explanation for this darkening, this likely occurs during part of the RAP scan cycle when the scan plane is aligned with the direction of motion, making the optics more susceptible to increased UV exposure and molecular contamination. Additionally, systematic daytime-nighttime longwave top-of-atmosphere (TOA) flux inconsistency was also detected during validation, which highlights the changes in the shortwave region of the total sensor. This paper briefly describes the strategy to correct for the sensor response changes and presents the improvements in CERES Edition 4 data products, which incorporates these sensor response changes in the computation of radiances.

  6. A theoretical study on area compensation for non-directly-south-facing solar collectors

    International Nuclear Information System (INIS)

    Solar energy integrated with the building is an important approach for the synchronous development of solar energy and architecture. The energy gain of the solar collector integrated with the pitched roof has been greatly influenced by the roof azimuth and tilted angle. Investment cost of the collectors is mainly decided by the size of the collector area. Accordingly, it is significant for solar building design to economically determinate the area compensation of the solar collector at different azimuth and tilted angles. Take Kunming and Beijing as examples, area compensation for the flat-plate tube-fin solar collector used in southern regions and the evacuated tube collector with cylindrical absorbers used in northern regions in China have been theoretically calculated. The results to some extent show that the daily horizontal solar radiation, ambient temperature, the azimuth and tilted angle of the collector integrated into the roof have an influence on the area compensation. The azimuth angle and tilted angle of the roof are the main factors that influence the A/A , which is defined as the collector area ratio of the non-south-facing collectors to the south-facing ones with the optimal tilted angle. Comparative studies found that the range of A/A for the evacuated tube collector used in the northern regions is close to that for the flat-plate tube-fin solar collector used in the southern regions. When the pitched roof tilted angle ? element of [25 deg., 45 deg.] and the azimuth angle vertical bar ? vertical bar ? 30 deg., the collectors can intercept a lot of solar radiant-energy. Considering the economic situations of the ordinary consumers in China, the optimal area compensation A/A ? 1.30 is recommended in this paper

  7. Energy analysis and improvement potential of finned double-pass solar collector

    International Nuclear Information System (INIS)

    Highlights: • The developed steady state model predicting the thermal performance of double-pass solar collectors is presented. • The main objective of this paper is to analyze the energy and exergy of finned double-pass solar collector. • A new mathematical model, solution procedure, and test results are presented. • The thermal performances and improvement potential of the double-pass solar collectors are discussed. - Abstract: Steady state energy balance equations for the finned double-pass solar collector have been developed. These equations were solved using the matrix inversion method. The predicted results were in agreement with the results obtained from the experiments. The predictions and experiments were observed at the mass flow rate ranging between 0.03 kg/s and 0.1 kg/s, and solar radiation ranging between 400 W/m2 and 800 W/m2. The effects of mass flow rates and solar radiation levels on energy efficiency, exergy efficiency and the improvement potential have been observed. The optimum energy efficiency is approximately 77%, which was observed at the mass flow rate of 0.09 kg/s. The optical efficiency of the finned double-pass solar collector is approximately 70–80%. The exergy efficiency is approximately 15–28% and improvement potential of 740–1070 W for a solar radiation of 425–790 W/m2

  8. Cloud Effects on Meridional Atmospheric Energy Budget Estimated from Clouds and the Earth's Radiant Energy System (CERES) Data

    Science.gov (United States)

    Kato, Seiji; Rose, Fred G.; Rutan, David A.; Charlock, Thomas P.

    2008-01-01

    The zonal mean atmospheric cloud radiative effect, defined as the difference of the top-of-atmosphere (TOA) and surface cloud radiative effects, is estimated from three years of Clouds and the Earth's Radiant Energy System (CERES) data. The zonal mean shortwave effect is small, though it tends to be positive (warming). This indicates that clouds increase shortwave absorption in the atmosphere, especially in midlatitudes. The zonal mean atmospheric cloud radiative effect is, however, dominated by the longwave effect. The zonal mean longwave effect is positive in the tropics and decreases with latitude to negative values (cooling) in polar regions. The meridional gradient of cloud effect between midlatitude and polar regions exists even when uncertainties in the cloud effect on the surface enthalpy flux and in the modeled irradiances are taken into account. This indicates that clouds increase the rate of generation of mean zonal available potential energy. Because the atmospheric cooling effect in polar regions is predominately caused by low level clouds, which tend to be stationary, we postulate that the meridional and vertical gradients of cloud effect increase the rate of meridional energy transport by dynamics in the atmosphere from midlatitude to polar region, especially in fall and winter. Clouds then warm the surface in polar regions except in the Arctic in summer. Clouds, therefore, contribute in increasing the rate of meridional energy transport from midlatitude to polar regions through the atmosphere.

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

    Science.gov (United States)

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

    2008-01-01

    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".

  10. Radiant Heating and Cooling Systems. Part one

    DEFF Research Database (Denmark)

    Kim, Kwan Woo; Olesen, Bjarne W.

    2015-01-01

    The use of radiant heating systems has several thousand years of history.1,2 The early stage of radiant system application was for heating purposes, where hot air from flue gas (cooking, fires) was circulated under floors or in walls. After the introduction of plastic piping water-based radiant heating and cooling with pipes embedded in room surfaces (floor, wall, and ceiling), the application increased significantly worldwide. Earlier application of radiant heating systems was mainly for residential buildings because of its comfort and free use of floor space without any obstruction from installations. For similar reasons, as well as possible peak load reduction and energy savings, radiant systems are being widely applied in commercial and industrial buildings.

  11. A review of collector and energy storage technology for intermediate temperature applications

    Science.gov (United States)

    Wyman, C.; Castle, J.; Kreith, F.

    1980-01-01

    The technology and thermal performance of intermediate temperature solar collectors is summarized and the status of thermal and thermo-chemical storage methods is reviewed. It is concluded that collector technology is commercially available to achieve delivery temperatures up to 350 F at averaged yearly efficiencies better than 30 per cent in good solar climates and that linear parabolic, single-axis tracking troughs are the best types of collectors currently available for intermediate temperature applications. On the other hand, energy storage options commercially available today are generally limited to sensible heat systems, which are bulky and expensive for long-term storage. More research is necessary to develop new storage concepts such as intermediate temperature chemical heat pumps based on reversible reactions, suitable for intermediate temperature solar systems with significant storage capability.

  12. Using Lunar Observations to Validate In-Flight Calibrations of Clouds and Earth Radiant Energy System Instruments

    Science.gov (United States)

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

    2014-01-01

    The validation of in-orbit instrument performance requires stability in both instrument and calibration source. This paper describes a method of validation using lunar observations scanning near full moon by the Clouds and Earth Radiant Energy System (CERES) instruments. Unlike internal calibrations, the Moon offers an external source whose signal variance is predictable and non-degrading. From 2006 to present, in-orbit observations have become standardized and compiled for the Flight Models-1 and -2 aboard the Terra satellite, for Flight Models-3 and -4 aboard the Aqua satellite, and beginning 2012, for Flight Model-5 aboard Suomi-NPP. Instrument performance parameters which can be gleaned are detector gain, pointing accuracy and static detector point response function validation. Lunar observations are used to examine the stability of all three detectors on each of these instruments from 2006 to present. This validation method has yielded results showing trends per CERES data channel of 1.2% per decade or less.

  13. Pulsed depressed collector

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Mark A

    2015-11-03

    A high power RF device has an electron beam cavity, a modulator, and a circuit for feed-forward energy recovery from a multi-stage depressed collector to the modulator. The electron beam cavity include a cathode, an anode, and the multi-stage depressed collector, and the modulator is configured to provide pulses to the cathode. Voltages of the electrode stages of the multi-stage depressed collector are allowed to float as determined by fixed impedances seen by the electrode stages. The energy recovery circuit includes a storage capacitor that dynamically biases potentials of the electrode stages of the multi-stage depressed collector and provides recovered energy from the electrode stages of the multi-stage depressed collector to the modulator. The circuit may also include a step-down transformer, where the electrode stages of the multi-stage depressed collector are electrically connected to separate taps on the step-down transformer.

  14. A full-scale experimental set-up for assessing the energy performance of radiant wall and active chilled beam for cooling buildings

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per

    2015-01-01

    Full-scale experiments under both steady-state and dynamic conditions have been performed to compare the energy performance of a radiant wall and an active chilled beam. From these experiments, it has been observed that the radiant wall is a more secure and efficient way of removing heat from the test room than the active chilled beam. The energy saving, which can be estimated to around 10%, is due to increased ventilation losses. The asymmetry between air and radiant temperature, the air temperature gradient and the possible short-circuit between inlet and outlet play an equally important role in decreasing the cooling need of the radiant wall compared to the active chilled beam. It has also been observed that the type and repartition of heat load have an influence on the cooling demand. Regarding the comfort level, both terminals met the general requirements, except at high solar heat gains: overheating has been observed due to the absence of solar shading and the limited cooling capacity of the terminals. No local discomfort has been observed although some segments of the thermal manikin were slightly colder.

  15. Method for decreasing radial temperature gradients of crystal growth melts utilizing radiant energy absorptive materials and crystal growth chambers comprising such materials

    International Nuclear Information System (INIS)

    A method for reducing the radial temperature gradient of a radiant energy emitting heated body is described. The method comprises insulating such heated body with a refractory insulating material containing an efficient absorber of the radiant energy emitted by said heated body. Specifically, materials containing trivalent dysprosium are disclosed as suitable thermal insulation for use where the heated body is at a temperature in the 18000 C.-25000 C. range. Also described is a crystal growth chamber for pulling unicrystalline compositions from a melt utilizing the Czochralski technique. The chamber is characterized by the placement of a refractory insulating material containing an efficient absorber of near infrared radiation around a crucible which contains the melt. Dysprosium is specifically disclosed as an efficient absorber of the near infrared radiation which is emitted by melt and crucible at the elevated temperatures employed for boule formation utilizing the Czochralski technique

  16. Economic analysis of flat plate collectors of solar energy

    International Nuclear Information System (INIS)

    Although solar energy potential in Turkey is far more than its total annual energy consumption, because of technical, economic and efficiency problems it cannot be harnessed to its fullest extent. Solar energy collecting systems have an initial cost two to five times higher than alternatives using electricity, LPG, fuel or other solid energy sources. However, their annual repair and maintenance costs are much lower than alternatives due to high energy prices. Solar systems with inflated annual costs have a minimum present value of US$867.19. Solar energy systems can be recommended for the countries that want a dependable and environmentally sound energy source. However, investment in R and D activities is necessary to reduce total cost of the system through improved efficiency and better production technology. (author)

  17. Testing solar collectors as an energy source for a heat pump

    Energy Technology Data Exchange (ETDEWEB)

    Georgiev, A. [Department of Mechanics, Technical University of Sofia, branch Plovdiv, P.O. Box 7, 4023 Plovdiv (Bulgaria)

    2008-04-15

    The article presents the experimental study of a heat pump possessing solar collectors as an energy source. A method to test the combined work of collectors delivering heat to the evaporator of a heat pump was devised. The layout of the test facility is shown and the system construction with the measurement equipment is described. The planning experiment to test the installation was chosen. The medium fluid condenser temperature anti t{sub c}, the fluid condenser mass flow rate m{sub c} and the medium fluid evaporator temperature anti t{sub ev} were chosen as experiment factors to determine both objective functions - the coefficient of performance (COP) of the heat pump and the efficiency of the system {eta}{sub s}. The reverberation of both objective functions is shown. (author)

  18. Solar collectors in Greece

    International Nuclear Information System (INIS)

    The use of regenerative energies began in greece in 1974. Solar energy for hot water preparation has evolved best mainly for favourable climatic conditions. More than 50% of Europe's collector capacity is produced and used in Greece. Solar energy, collectors, heat pump, alternative energies are terms used by greece people in day-to-day life. The author discusses the significance of the greece solar market and its economic aspects. (orig.)

  19. 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

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

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per

    2011-01-01

    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 of...

  1. 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

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

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per

    2011-01-01

    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.

  3. Partial conversion of current collectors into nickel copper oxide electrode materials for high-performance energy storage devices.

    Science.gov (United States)

    Zhang, Liuyang; Gong, Hao

    2015-07-22

    A novel substrate sacrifice process is proposed and developed for converting part of a current collector into supercapacitor active materials, which provides a new route in achieving high energy density of supercapacitor device. Part of a copper foam current collector is successfully converted into highly porous nickel copper oxide electrode for light- and high-performance supercapacitors. Remarkably, this strategy circumvents the problem associated with poor contact interface between electrode and current collector. Meanwhile, the overall weight of the supercapacitor could be minimized. The charge transfer kinetics is improved while the advantage of the excellent mechanical properties of metal current collector is not traded off. By virtue of this unique current collector self-involved architecture, the material derived from the current collector manifests large areal capacitance of 3.13 F cm(-2) at a current density of 1 A g(-1). The capacitance can retain 2.97 F cm(-2) at a much higher density (4 A g(-1)). Only a small decay of 6.5% appears at 4 A g(-1) after 1600 cycles. The strategy reported here sheds light on new strategies in making additional use of the metal current collector. Furthermore, asymmetric supercapacitor using both solid-state gel electrolyte and liquid counterpart are obtained and analyzed. The liquid asymmetric supercapacitor can deliver a high energy density up to 0.5 mWh cm(-2) (53 Wh kg(-1)) at a power density of 13 mW cm(-2) (1.4 kW kg(-1)). PMID:26098672

  4. Dust collector

    International Nuclear Information System (INIS)

    The present invention is directed to a dust collector. Dust collector (100) has a housing (102) separated by partition into inlet chamber and clean air chamber. A clean air drum rotatably supports columns of horizontally extending, filter elements. A low pressure, high volume pulse apparatus is operable through blowpipe to sequentially provide a low pressure reverse pulse to a column of filter elements thereby separating any dust cake from them and allowing it to fall into conical portion for removal from collector by air lock. The motor which rotates blowpipe also disengageably rotates clean air drum and attached filter elements to align a column of filter elements with door assembly for maintenance

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

    Directory of Open Access Journals (Sweden)

    Zhiyong Yang

    2011-03-01

    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.

  6. Radiant Floor Cooling Systems

    DEFF Research Database (Denmark)

    Olesen, Bjarne W.

    2008-01-01

    In many countries, hydronic radiant floor systems are widely used for heating all types of buildings such as residential, churches, gymnasiums, hospitals, hangars, storage buildings, industrial buildings, and smaller offices. However, few systems are used for cooling.This article describes a floor cooling system that includes such considerations as thermal comfort of the occupants, which design parameters will influence the cooling capacity and how the system should be controlled. Examples of ap...

  7. Performance evaluation and collector sizing for solar energy operated/assisted absorption machines under local climatic conditions

    International Nuclear Information System (INIS)

    This paper presents the theoretical performance of solar energy operated/assisted continuous absorption air conditioning machines while operating under local climatic conditions. The two most commonly used pairs of working fluids i.e. LiBr-H/sub 2/O and NH/sub 3/ -H /sub 2/O have been employed in the study the thermodynamic analysis of the two absorption machines has been reported while operating in air conditioning mode and deriving input heat for the vapor generator from a flat plate solar collector. The COP, the relative solution circulation ratio and the energy transfer at various points in the system are also reported for both LiBr-H/sub 2/O and NH/sub 3/-H/sub 2/O absorption machines. The monthly average daily solar energy collected to drive the absorption machines and utilizability of solar energy while operating the hot water solar collector at the temperature of generation have been discussed. The collector aperture area required per TR (ton of refrigeration has been estimated for both the absorption machines. Monthly average daily collector efficiencies are also reported for the three summer months. Finally, the operating cost of VCS, gas operated VAS and solar energy operated VAS have been reported and conclusions have been made. (author)

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

    Directory of Open Access Journals (Sweden)

    Giovanni Angrisani

    2014-10-01

    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.

  9. Thin-film black-and-white coatings for solar energy collectors

    Energy Technology Data Exchange (ETDEWEB)

    Li, V.V.; Faiziev, Sh.A.; Gaziev, U.Kh.; Trukhov, V.S.

    1977-01-01

    The development of selective coatings based on alternating layers of SiO/sub 2/ and Mo and also CeO/sub 2/ and Mo for solar energy collectors is discussed. The spectral characteristics of the developed coatings SiO/sub 2/-Mo-SiO/sub 2/, CeO/sub 2/-Mo-CeO/sub 2/ in the solar portion of the spectrum are presented. The coatings have good optical characteristics: integral absorptivity of 0.86 to 0.9 and integral emissivity of 0.06 to 0.1. The coatings were applied to the surface of stainless steel, molybdenum foil, and glass covered with a nontransparent aluminum layer.

  10. Super-radiant plasmon mode is more efficient for SERS than the sub-radiant mode in highly packed 2D gold nanocube arrays

    Science.gov (United States)

    Mahmoud, Mahmoud A.

    2015-08-01

    The field coupling in highly packed plasmonic nanoparticle arrays is not localized due to the energy transport via the sub-radiant plasmon modes, which is formed in addition to the regular super-radiant plasmon mode. Unlike the sub-radiant mode, the plasmon field of the super-radiant mode cannot extend over long distances since it decays radiatively with a shorter lifetime. The coupling of the plasmon fields of gold nanocubes (AuNCs) when organized into highly packed 2D arrays was examined experimentally. Multiple plasmon resonance optical peaks are observed for the AuNC arrays and are compared to those calculated using the discrete dipole approximation. The calculated electromagnetic plasmon fields of the arrays displayed high field intensity for the nanocubes located in the center of the arrays for the lower energy super-radiant mode, while the higher energy sub-radiant plasmon mode displayed high field intensity at the edges of the arrays. The Raman signal enhancement by the super-radiant plasmon mode was found to be one hundred fold greater than that by sub-radiant plasmon mode because the super-radiant mode has higher scattering and stronger plasmon field intensity relative to the sub-radiant mode.

  11. Satellite Collectors of Solar Energy for Earth and Colonized Planet Habitats

    Science.gov (United States)

    Kusiolek, Richard

    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,

  12. 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

  13. Solar collector. Sonnenkollektor

    Energy Technology Data Exchange (ETDEWEB)

    Cost, K.

    1984-01-05

    Because of the relatively low energy density of the solar radiation reaching the earth's surface, special solar collectors which are cheap to manufacture, transport and erect have to be designed. These requirements are not fulfilled to a sufficient extent in the previously known solar collectors. In the invention, two plastic foils lying above one another are connected by line welds, so that chambers lying on top of one another are formed, where the heat medium (water) can flow down from the top chamber to the next one etc. The plastic foils are spot welded at many places inside the chambers, so that the chambers will not swell up into a ball under the pressure of water, but will retain their flat shape. This design permits the exclusive use of thin plastic foil for manufacturing the solar collectors, and thus produces very low costs for manufacture, transport and erection. The main application consists of heating water. (orig.).

  14. 3X compound parabolic concentrating (CPC) solar energy collector. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Ballheim, R.W.

    1980-04-25

    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.

  15. Heat yield and characteristics of solar collectors

    International Nuclear Information System (INIS)

    The test results of the summer 1980 test on solar collectors are summarised. Apart from the 16 collectors tested under contract, two were investigated as a reference serving flat collectors, e.g. for the area of International Energy Agency (IEA), two were evacuated cylindrical collectors. The report allows the comparison of heat power outputs of the different products on the basis of the measured optical and thermal data values. (A.N.K.)

  16. 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)

    Latta, A.F.

    1976-03-26

    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)

  17. Thermal model of attic systems with radiant barriers

    Energy Technology Data Exchange (ETDEWEB)

    Wilkes, K.E.

    1991-07-01

    This report summarizes the first phase of a project to model the thermal performance of radiant barriers. The objective of this phase of the project was to develop a refined model for the thermal performance of residential house attics, with and without radiant barriers, and to verify the model by comparing its predictions against selected existing experimental thermal performance data. Models for the thermal performance of attics with and without radiant barriers have been developed and implemented on an IBM PC/AT computer. The validity of the models has been tested by comparing their predictions with ceiling heat fluxes measured in a number of laboratory and field experiments on attics with and without radiant barriers. Cumulative heat flows predicted by the models were usually within about 5 to 10 percent of measured values. In future phases of the project, the models for attic/radiant barrier performance will be coupled with a whole-house model and further comparisons with experimental data will be made. Following this, the models will be utilized to provide an initial assessment of the energy savings potential of radiant barriers in various configurations and under various climatic conditions. 38 refs., 14 figs., 22 tabs.

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

    Science.gov (United States)

    Nichols, L. D.

    1976-01-01

    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.

  19. Solar collector array

    Energy Technology Data Exchange (ETDEWEB)

    Hall, John Champlin; Martins, Guy Lawrence

    2015-09-06

    A method and apparatus for efficient manufacture, assembly and production of solar energy. In one aspect, the apparatus may include a number of modular solar receiver assemblies that may be separately manufactured, assembled and individually inserted into a solar collector array housing shaped to receive a plurality of solar receivers. The housing may include optical elements for focusing light onto the individual receivers, and a circuit for electrically connecting the solar receivers.

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

    Science.gov (United States)

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

    2013-07-01

    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.

  1. Radiant Heating and Cooling Systems. Part one

    DEFF Research Database (Denmark)

    Kim, Kwan Woo; Olesen, Bjarne W.

    2015-01-01

    The use of radiant heating systems has several thousand years of history.1,2 The early stage of radiant system application was for heating purposes, where hot air from flue gas (cooking, fires) was circulated under floors or in walls. After the introduction of plastic piping water-based radiant heating and cooling with pipes embedded in room surfaces (floor, wall, and ceiling), the application increased significantly worldwide. Earlier application of radiant heating systems was mainly for reside...

  2. Air/liquid collectors

    DEFF Research Database (Denmark)

    Jensen, Søren Østergaard; Olesen, Ole; Kristiansen, Finn Harken

    1997-01-01

    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 preheati...

  3. Comparison of Thermal Comfort by Radiant Heating and Convective Heating

    Directory of Open Access Journals (Sweden)

    Shigeru Imai

    2015-01-01

    Full Text Available Currently, convective heating with a heat-pump system, which has high energy efficiency, is popular for room heating. However, it is possible that energy savings using convective heating can be further improved using heat pumps that service both occupied and unoccupied spaces. Moreover, convective heating increases vertical temperature gradients in a room; thus, it is hard to say whether occupants are being provided with sufficient thermal comfort. The purpose of this study is to compare the thermal comfort provided by both radiant and convective heating systems. In this study, a small office room was modeled, and then temperature and airflow distributions in the room were calculated by Computational Fluid Dynamics (CFD simulations using ESP-r (Environmental research simulation software. Furthermore, distributions of Standard Effective Temperatures (SET* were calculated using the air temperature distributions obtained from the CFD simulations, which allows us to compare the thermal comfort provided by convective heating with that provided by radiant heating. The results show that radiant heating can provide satisfactory thermal comfort, even when the room air temperature is low. However, thermal comfort also depends on the temperature of blowing air, and blowing air must reach occupied regions; thus, only radiant heating cannot circulate sufficient air. In contrast, convective heating increases vertical temperature gradients in a room. Therefore, rather than using only radiant or convective heating, it may be more effective to combine them efficiently.

  4. A search for space energy alternatives

    Science.gov (United States)

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

    1978-01-01

    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.

  5. Heat yield and characteristics of solar collectors

    International Nuclear Information System (INIS)

    The results of the EIR collector test series of the summers 1978 and 1979 are presented. In total, there are 37 different collectors available on the Swiss market. The results are compared with those from the IEA (International Energy Agency) of presuggested reference collectors. Test methods are described and also the construction of the test bench. Also, briefly described is a development method for the calculation of gross heat yield from solar collectors. Then the characteristics of the reference collectors in connection with the test periods are considered, and their role in the calculation of results of single collector test series explained. A description of the spectral photometer is given. (A.N.K.)

  6. Radiant floor cooling coupled with dehumidification systems in residential buildings: A simulation-based analysis

    International Nuclear Information System (INIS)

    Highlights: • The floor radiant cooling in a typical apartment is analyzed. • Dehumidification devices, fan-coil and mechanical ventilation are compared. • The results are analyzed in terms of both thermal comfort and energy consumption. • The energy consumption of the dehumidifiers is higher than that of other systems. • The mechanical ventilation decreases the moisture level better than other systems. - Abstract: The development of radiant cooling has stimulated an interest in new systems based on coupling ventilation with radiant cooling. However, radiant cooling systems may cause condensation to form on an active surface under warm and humid conditions during the cooling season. This phenomenon occurs when surface temperature falls below dew point. To prevent condensation, air humidity needs to be reduced with a dehumidification device or a mechanical ventilation system. There are two main options to achieve this. The first is to use dehumidification devices that reduce humidity, but are not coupled with ventilation, i.e. devices that handle room air and leave air change to infiltrations. The second is to combine a mechanical ventilation system with dehumidifying finned coils. This study analyzes the floor radiant cooling of a typical residential apartment within a multi-storey building in three Italian climate zones by means of a detailed simulation tool. Five systems were compared in terms of both indoor thermal comfort and energy consumption: radiant cooling without dehumidification; radiant cooling with a soft dehumidification device; radiant cooling with a dehumidification device which also supplies sensible cooling; radiant cooling coupled with fan coils; and radiant cooling with a mechanical ventilation system which dehumidifies and cools

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

    CERN Document Server

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

    2012-01-01

    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.

  8. Solar thermal collector

    OpenAIRE

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

    2011-01-01

    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

  9. Energy flow and thermal comfort in buildings : Comparison of radiant and air-based heating & cooling systems

    DEFF Research Database (Denmark)

    Le Dreau, Jerome

    2014-01-01

    Varme- og køleanlæg kan inddeles i to hovedkategorier: konvektive systemer (fx. aircondition, aktiv kølebaffel, fan-coils) og stråle køling/varme systemer. De to systemer har forskellige former for varmeoverførsel; den første er hovedsageligt baseret på konvektion, mens den anden er baseret på både stråling og konvektion. Strålevarmesystemer har den fordel at kunne gøre brug af lav kilder (dvs. opvarmning ved lave temperature og køling ved høje temperaturer) og dermed reducere bygningers primære energiforbrug. Der er imidlertid en mangel på viden om varmeoverførsel fra terminalen mod rummet og på de parametre, der påvirker anlæggenes ydelse. Derfor er der foretaget en sammenligning af komfortbetingelserne og energiforbruget for fire typer anlæg (aktiv kølebaflen, strålende gulv, væg og loft) for et typisk kontorlokale, både numerisk og eksperimentelt. Fra den stationære numerisk analyse og fuldskalaforsøgene er det observeret, at forskellen mellem de to typer anlæg primært skyldes ændringer ventilationstab. Ved lave ventilationstilskud (under 0,5 ACH), har stråle- og luftbaserede systemer samme energibehov. Ved højere ventilationstilskud er strålevarmesystemers energiforbrug lavere end de luftbaserede systemers på grund af den højere lufttemperatur. Ved 2 ACH kan en strålevægs energibesparelser vurderes til ca. 10 % sammenlignet med den aktive kølebaflen (med hensyn til leveret energi). Asymmetrien mellem luft og strålingstemperatur, lufttemperaturgradienten og den mulige kortslutning mellem indløb og udløb spiller en lige så vigtig rolle ved reduceringen af strålevæggens kølebehov sammenlignet med den aktive kølebaflen. Jo højere et luftskifte og jo højere, jo større er de opnåede besparelser med en strålekølesystem. Derfor har strålekølesystemet et stort potentiale for energibesparelser i bygninger med et højt ventilationskifte (fx butikker, togstation, industriel opbevaring ). Blandt strålesystemer er der kun observeret små forskelle i den påtænkte geometri. Kun hvis beboerne antages at sidde ned, kan den store vinkelforhold med gulvet føre til en reduktion af energibehovet for gulvkølesystemer. Disse konklusioner gælder for fler-etagers eller højisolerede bygninger (R > 5 m2.K/W). Når det drejer sig om en enetagers bygning med et lavt isoleringsniveau, er strålesystemers effektivitet lavere på grund af de større klimaskærmstab, og et luftbaseret system kan være mere energieffektivt end et stråleanlæg (med hensyn til leveret energi). Et tilsvarende globalt komfort niveau er blevet observeret for stråle- og luftbaserede systemer i både numeriske og eksperimentelle undersøgelser, men de forskellige anlæg opnåede ikke den samme ensartethed i rummet. Den aktive kølebaflen opnår teoretisk de mest ensartede komfortbetingelser (når der ses bort fra risikoen for træk) efterfulgt af kølelofter. De mindst ensartede betingelser blev opnået med det afkølede gulv, på grund af store forskelle mellem siddende og stående stilling. Lokale komfortbetingelser (strålingstemperaturasymetrien, lufttemperaturgradient, risiko for træk) er også blevet evalueret både teoretisk og numerisk, og der er ikke observeret ubehag ved normal kølekapacitet. Udover denne sammenlignende undersøgelse af forskellige anlæg, er sammenhængen mellem kølesystemer og interne konvektionsstrømme også blevet undersøgt eksperimentelt. Sammenligningen med eksisterende modeller påpegede specificiteten af eksisterende sammenhænge og begrænsningen i deres anvendelsesområder. På grund af forskelle i indblæsning stråle, har eksisterende korrelationer en tendens til at overvurdere konvektionsstrømningen, især ved loftet. To fremgangsmåder er således blevet testet for bedre at kunne forklare strømingsformer i definitionen af konvektion koefficienter. Ved den første fremgangsmåde blev lokale værdier af lufthastigheden anvendt til at evaluere konvektion ved loftet. En alternativ fremgangsmåde består i at inkludere et modificeret Archimedes tal i definitionen af ko

  10. Predictive control of intermittently operated radiant floor heating systems

    Energy Technology Data Exchange (ETDEWEB)

    Cho, S.H. [Korea Inst. of Energy Research, Taejon (Korea); Zaheer-Uddin, M. [Concordia Univ., Centre for Building Studies, Montreal (Canada)

    2003-05-01

    A predictive control strategy as a means of improving the energy efficiency of intermittently heated radiant floor heating systems is explored. Both computer simulations and experiments are conducted to assess and compare the energy performance of the predictive control strategy with an existing conventional control strategy. The results show that use of the predictive control strategy could save between 10% and 12% energy during the cold winter months. The energy savings are somewhat higher during mild weather conditions. (Author)

  11. 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

  12. Hybrid Photovoltaic-Thermal Collectors: A Review

    Science.gov (United States)

    Ramos, Figueiredo; Cardoso, António; Alcaso, Adérito

    Solar energy can be converted directly into electric and thermal energy through photovoltaic cells and thermal collectors, respectively. However this conversion, in particular the photovoltaic, has a reduced efficiency. A solution proposed to increase this efficiency is with the hybrid solar structure, which consists in the junction of the photovoltaic panel and the thermal collector in a single module. The interest on these solar systems led the International Energy Agency to create a "Task" on this subject. This paper presents a review of the research in this area, presenting the definitions of the related collectors and results of their characteristics, as well as some ideas for future studies.

  13. Collector Failures on 350 MHz, 1.2 MW CW Klystrons at the Low Energy Demonstration Accelerator (LEDA)

    CERN Document Server

    Rees, D; Bradley, J

    2000-01-01

    We are currently operating the front end of the accelerator production of tritium (APT) accelerator, a 7 MeV radio frequency quadrapole (RFQ) using three, 1.2 MW CW klystrons. These klystrons are required and designed to dissipate the full beam power in the collector. The klystrons have less than 1500 operational hours. One collector has failed and all collectors are damaged. This paper will discuss the damage and the difficulties in diagnosing the cause. The collector did not critically fail. Tube operation was still possible and the klystron operated up to 70% of full beam power with excellent vacuum. The indication that finally led us to the collector failure was variable emission. This information will be discussed. A hydrophonic system was implemented to diagnose collector heating. The collectors are designed to allow for mixed-phase cooling and with the hydrophonic test equipment we are able to observe: normal, single-phase cooling, mixed-phase cooling, and a hard boil. These data will be presented. The...

  14. A collector testbench for electron coolers

    International Nuclear Information System (INIS)

    A new collector design for electron coolers was elaborated in the Karlsruhe electron cooling group at LEAR (CERN). For testing the performance of the collector a linear set-up was built with an electron beam of energies up to 20 keV and currents up to 1.25 A. In the present stage maximum collector perveance of 37 ?AV-3/2 can be obtained. Loss rates are well in the 10-5 region for collector perveances of ?25 ?AV-3/2. The collector was investigated in detail and a new type of computerized control and monitor system was tested based on a Macintosh Plus personal computer with a special interface for CAMAC and VME. (orig.)

  15. Movable air solar collector and its efficiency

    International Nuclear Information System (INIS)

    Implementing the guidelines of the Latvian National Programme for Energy in the field of alternative energy, intensive research shall be carried on regarding the use of solar energy, as it can be successfully used not only for the purposes of water heating and production of electrical energy, but also for air warming. The amount of heat necessary for the drying of rough forage and grain drying by active aeration in June, July and August can be obtained using solar radiation. The Latvian Guidelines for the Energy Development 2006-2016 state that the solar radiance in Latvia is of quite low intensity. The total amount of solar energy is 1109 kWh m-2 per year. The period of usage of the solar thermal energy is beginning from the last decade of April, when the intensity of radiation is 120 kWh m-2, until the first decade of September. Within this period (approximately 1800 hours), it is possible to use the solar thermal energy by placing solar collectors. The usage of solar collectors for in drying of agricultural production is topical from the viewpoint of decreasing the consumption of energy used for the drying, as electrical energy and fossil energy resources become more expensive and tend to run out. In the processes that concern drying of agricultural production, efficiently enough solar radiation energy can be used. Due to this reason researching continues and expands in the field of usage of solar energy for the processes of drying and heating. The efficiency factor of the existing solar collectors is not high, but they are of simple design and cheep for production and exploitation. By improving the design of the solar collectors and choosing modern materials that absorb the solar radiation energy, it is possible the decrease the efficiency factor of solar collectors and decrease the production costs. In the scientific laboratory of grain drying and storage of Latvia University of Agriculture, a pilot device movable folding solar collector pilot device suitable for Latvia has been developed and constructed. Within the article, the movable folding solar collector is described, which has been constructed as a solar collector of module types for being able to move and unfold it in the place of work. The solar collector serves as an experimental prototype, as well as simultaneously as a ground for comparative researches in solar absorbent air. The solar collector serves as an experimental prototype and simultaneously also as a carrying surface for comparative researches in solar absorbent air. In the researches, the roof coverings available in Latvia and their suitability for construction of solar collectors will be compared. (author)

  16. Phase 1 of the First Solar Small Power System Experiment (experimental System No. 1). Volume 1: Technical Studies for Solar Point-focusing, Distributed Collector System, with Energy Conversion at the Collector, Category C

    Science.gov (United States)

    Clark, T. B. (editor)

    1979-01-01

    The technical and economic feasibility of a solar electric power plant for a small community is evaluated and specific system designs for development and demonstration are selected. All systems investigated are defined as point focusing, distributed receiver concepts, with energy conversion at the collector. The preferred system is comprised of multiple parabolic dish concentrators employing Stirling cycle engines for power conversion. The engine, AC generator, cavity receiver, and integral sodium pool boiler/heat transport system are combined in a single package and mounted at the focus of each concentrator. The output of each concentrator is collected by a conventional electrical distribution system which permits grid-connected or stand-alone operation, depending on the storage system selected.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-09-01

    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.

  18. Short-Term Solar Collector Power Forecasting

    OpenAIRE

    Bacher, Peder; Madsen, Henrik; Perers, Bengt

    2011-01-01

    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...

  19. Radiant zone heated particulate filter

    Science.gov (United States)

    Gonze, Eugene V [Pinckney, MI

    2011-12-27

    A system includes a particulate matter (PM) filter including an upstream end for receiving exhaust gas and a downstream end. A radiant zoned heater includes N zones, where N is an integer greater than one, wherein each of the N zones includes M sub-zones, where M is an integer greater than or equal to one. A control module selectively activates at least a selected one of the N zones to initiate regeneration in downstream portions of the PM filter from the one of the N zones, restricts exhaust gas flow in a portion of the PM filter that corresponds to the selected one of the N zones, and deactivates non-selected ones of the N zones.

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

    DEFF Research Database (Denmark)

    Krajcik, Michal; Tomasi, Roberta; Simone, Angela; Olesen, Bjarne W.

    2012-01-01

    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 a...

  1. Optimal nonimaging integrated evacuated solar collector

    Science.gov (United States)

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

    1993-11-01

    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.

  2. 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)

  3. 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 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)

  4. Transpired solar collectors for ventilation air heating

    OpenAIRE

    Hall, R; WANG X.; Ogden, R; Elghali, L.

    2011-01-01

    Transpired solar collectors (TSCs) improve the environmental performance of buildings by preheating incoming ventilation air using solar energy, substituting the need to use fossil fuels. TSCs have been used successfully in the USA and Canada over the past 20 years and have been shown to achieve economic payback of between 2 and 10 years. The economic performance is achieved through a combination of high thermal efficiency and the low cost of the solar collector, which is in the form of a sin...

  5. Solar energy system design: A simple method for sizing the collector field and thermal storage

    Science.gov (United States)

    Peters, R. R.

    1981-07-01

    The Zero Marginal Cost (ZMC) technique to enable quick, accurate designs of parabolic trough solar energy systems was developed. The ZMC technique is discussed and it is shown that systems designed with this technique compare quite favorably with those designed using expensive computer codes.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stetiu, C.

    1998-01-01

    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.

  7. Performances and yield assessment of glazed photovoltaic-thermal collectors

    OpenAIRE

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

    2012-01-01

    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...

  8. Radiant vessel auxiliary cooling system

    International Nuclear Information System (INIS)

    This patent describes an improved radiant vessel passive cooling system for liquid-metal poor-type modular nuclear reactors having a reactor vessel and a surrounding containment vessel spaced apart from the reactor vessel to form a first interstitial region containing an inert gas, the improvement comprising: a shell spaced apart from and surrounding the containment vessel to form a second interstitial region comprising a circulatory air passage. The circulatory air passage has an air inlet at a first position and an air outlet at a second position which is vertically higher than the first position. The second interstitial region lies between the shell and the containment vessel; and surface area extension means in the shell is longitudinally disposed from the shell into the second interstitial region towards the containment vessel to receive thermal radiation from the containment vessel. The surface area extension means is spaced apart from the external surface of the containment vessel where heat radiated form the containment vessel is received at the surface extension means for convection, conduction and radiation to air in the circulatory passage

  9. City sewer collectors biocorrosion

    Science.gov (United States)

    Ksia&¸zdot; ek, Mariusz

    2014-12-01

    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.

  10. Target, purging magnet and electron collector design for scanned high-energy photon beams

    International Nuclear Information System (INIS)

    A new method for producing very narrow and intense 50 MV bremsstrahlung beams with a half-width as low as 35 mm at a distance of 1 m from the target is presented. Such a beam is well suited for intensity modulation using scanned photon beams. An algorithm has been developed to minimize the width of the bremsstrahlung beam generated in a multilayer target by varying the individual layer thicknesses and atomic numbers under given constraints on the total target thickness and the mean energy of the transmitted electrons. Under such constraints the narrowest possible bremsstrahlung beam is obtained with a target composed of layers of monotonically increasing atomic number starting with the lowest possible value at the entrance side where the electrons impinge. It is also shown that the narrowest photon beam profile is associated with the highest possible forward photon yield. To be able to use the optimized target clinically it is desirable to be able to collect and stop all the electrons that are transmitted through the target. The electrons are most efficiently collected if they are kept close together, i.e. by minimizing the multiple scatter of the electrons and consequently the half-width of the generated bremsstrahlung beam. This is achieved by a thin low-atomic-number target. A dedicated electron stopper has been developed and integrated with the purging magnet. When the electron stopper is combined with a purging magnet, a primary photon collimator and a multileaf collimator, almost all of the transmitted electrons and their associated bremsstrahlung contamination can effectively be collected. The narrow photon beams from thin low-atomic-number targets have the additional advantage of producing the hardest and most penetrative photon spectrum possible, which is ideal for treating large deep-seated tumours. (author)

  11. 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)

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

    2010-06-01

    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.

  12. Simulation Application for Optimization of Solar Collector Array

    Directory of Open Access Journals (Sweden)

    Igor Shesho*,

    2014-01-01

    Full Text Available Solar systems offer a comparatively low output density , so increasing the output always means a corresponding increase in the size of the collector area. Thus collector arrays are occasionally constructed (i.e. with different azimuth angles and/or slopes, which be imposed by the location and structure available to mount the collector. In this paper is developed simulation application for optimization for the solar collector array position and number of collectors in regard of maximum annual energy gain and thermal efficiency. It is analyzed solar collector array which has parallel and serial connected solar collectors with different tilt, orientation and thermal characteristics. Measurements are performed for determine the thermal performance of the system. Using the programming language INSEL it is developed simulation program for the analyzed system where optimization is done through parametric runs in the simulation program. Accent is given on the SE orientated collectors regarding their tilt and number, comparing two solutions-scenarios and the current system set situation of the in means of efficiency and total annual energy gain. The first scenario envisages a change of angle from 35 to 25 solar panels on the SE orientation, while the second scenario envisages retaining the existing angle of 35 and adding additional solar collector. Scenario 1 accounts for more than 13% energy gain on annual basis while Scenario 2 has 2% bigger thermal efficiency.

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

    DEFF Research Database (Denmark)

    Bava, Federico; Furbo, Simon; Perers, Bengt

    2015-01-01

    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 behavio...

  14. Stellate solar collector

    Energy Technology Data Exchange (ETDEWEB)

    Womack, R. R.

    1981-02-03

    A solar collector device of the type adapted for heating water and the like is disclosed. An elongated, opaque collector is provided with a plurality of radially extending vanes so as to define a hollow interior of stellate cross-section. Water is sprayed through a feeding conduit which extends through the hollow interior. As the sprayed water accumulates upon the interior vane surfaces, the collector wheel is rotated according to the weight of the deposited water. As the vane tips are rotated downwardly, the water is heated by conductive contact with the interior vane surfaces and by convection and radiation within the hollow interior. The heated water is then discharged downwardly through apertures in the vane tips into a collector pan. The invention is distinguished from the prior art in its introduction of the water upon the interior surfaces of collector vanes within a paddle wheel of stellate configuration, rather than upon the exterior surfaces of the vanes. The stellate configuration provides an increased area of exposure to the radiation of the sun within a compact unit and provides heating of the water by conduction, convection and radiation.

  15. Tracking system for solar collectors

    Science.gov (United States)

    Butler, B.

    1980-10-01

    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.

  16. 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

  17. Short-Term Solar Collector Power Forecasting

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Perers, Bengt

    2011-01-01

    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 sy...

  18. Data collection and performance reporting specifications for solar energy projects: A report of Task VI: The performance of solar heating, cooling, and hot water systems using evacuated collectors

    Energy Technology Data Exchange (ETDEWEB)

    Chandrashekar, M.; Vanoll, K.H.

    1986-06-01

    This report details the data collection and performance reporting specifications for solar energy projects that were developed by the International Energy Agency Task on the Performance of Solar Heating, Cooling and Hot Water Systems Using Evacuated Collectors. It was developed so that the Task Participants could exchange and present information about individual installations, their operating characteristics and performance results in an accurate and consistent manner. One of the main objectives of the effort was to ensure accurate collection and reporting of data, facilitating analysis and exchange of information among the participants. This document is based on the 1980 International Energy Agency document on reporting format which has been considerably revised. Specific requirements concerning the preparation of diagrams, figures, plots and textural material have evolved permitting more detailed comparisons and exchanges of information among installations. Format requirements include both simulated and measured data.

  19. Mathematical modelling of unglazed solar collectors under extreme operating conditions

    DEFF Research Database (Denmark)

    Bunea, M.; Perers, Bengt

    2015-01-01

    Combined heat pumps and solar collectors got a renewed interest on the heating system market worldwide. Connected to the heat pump evaporator, unglazed solar collectors can considerably increase their efficiency, but they also raise the coefficient of performance of the heat pump with higher average temperature levels at the evaporator. Simulation of these systems requires a collector model that can take into account operation at very low temperatures (below freezing) and under various weather conditions, particularly operation without solar irradiation.A solar collector mathematical model is developed and evaluated considering, the condensation/frost effect and rain heat gains or losses. Also wind speed and long wave irradiation on both sides of the collector are treated. Results show important heat gains for unglazed solar collectors without solar irradiation. Up to 50% of additional heat gain was found due to the condensation phenomenon and up to 40% due to frost under no solar irradiation. This work also points out the influence of the operating conditions on the collector's characteristics.Based on experiments carried out at a test facility, every heat flux on the absorber was separately evaluated so that this model can represent a valuable tool in optimising the design or the thermal efficiency of the collector. It also enables the prediction of the total energy yield for solar thermal collectors under extreme operating conditions.

  20. Optimum solar collector fluid flow rates

    DEFF Research Database (Denmark)

    Furbo, Simon; Shah, Louise Jivan

    1996-01-01

    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 ...

  1. 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)

    Theiss, Eric

    2013-10-15

    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.

  2. Fog collectors and collection techniques

    Science.gov (United States)

    Höhler, I.; Suau, C.

    2010-07-01

    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.

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

    DEFF Research Database (Denmark)

    Krajcik, Michal; Tomasi, Roberta

    2012-01-01

    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.

  4. New performance testing stand for the characterization of innovative collectors and optical components; Neuer Leistungsteststand zur Charakterisierung innovativer Kollektoren und optischer Komponenten

    Energy Technology Data Exchange (ETDEWEB)

    Fahr, Sven; Schaefer, Arim; Mehnert, Stefan; Kramer, Korbinian; Hess, Stefan; Thoma, Christoph; Richter, Jens; Stryi-Hipp, Gerhard [Fraunhofer Institut fuer Solare Energiesysteme, Freiburg (Germany); Luginsland, Frank [PSE AG, Freiburg (Germany)

    2010-07-01

    The variety of collector designs is on the increase. It is expected that technologies such as concentrating collectors, solar air collectors, heat pipe collectors and facade integrated collectors increase their market shares. In order to meet the various requirements for the measurement of this collector design, the Fraunhofer Institute for Solar Energy Systems (Freiburg, Federal Republic of Germany) and PSE-AG (Freiburg, Federal Republic of Germany) developed a new modular outdoor test stand was developed for performance testing. This test stand meets the highest requirements on tracking accuracy and flexibility. If necessary, mobile test equipment for testing of air temperature collectors and medium temperature collectors can be integrated easily.

  5. The CERN antiproton collector

    International Nuclear Information System (INIS)

    The Antiproton Collector is a new ring of much larger acceptance than the present accumulator. It is designed to receive 108 antiprotons per PS cycle. In order to be compatible with the Antiproton Accumulator, the momentum spread and the emittances are reduced from 6% to 0.2% and from 200 ? mm mrad to 25 ? mm mrad respectively. In addition to the ring itself, the new target area and the modifications to the stochastic systems of the Antiproton Accumulator are described. (orig.)

  6. Unglazed selective absorber solar air collector: Heat exchange analysis

    Science.gov (United States)

    Njomo, D.

    Unglazed solar air collectors show promise for applications such as ventilation air heating or crop drying. In this paper a mathematical model is developed to analyze the heat exchanges in an unglazed non-porous selective absorber air heater. It is shown that at quasi-steady state the energy balance equations of the components of the collector cascade into a single first order differential equation. The solution of this differential equation is written down as an explicit expression of the local temperature of the fluid flowing in the collector in terms of the time dependent solar intensity. The effect of various parameters such as the inlet fluid temperature, the mass flow rate, and the depth of the air channel on the thermal performances of the unglazed selective absorber collector are also studied. These performances are comparable to those of a conventional two glass covers air collector for low wind speeds.

  7. Heat collector for the dryer section of a papermaking machine

    Energy Technology Data Exchange (ETDEWEB)

    Urbas, J.C.

    1989-04-11

    In a papermaking machine comprising a drying section wherein a hood covers a series of dryer drums supported by the frame, the dryer drums convey an endless felt supporting a continuous sheet of pulp to be dried. At least one heat collector is provided for collecting high quality heat generated and concentrated in the immediate vicinity of the dryer drums. The heat collector defines an enclosure having bases, sides and ends wherein one of the bases is consituted by a plurality of the dryer drums. The heat collector also contains an exhaust system to separately evacuate the high quality heat collected within the heat collector from the low quality heat collected by the hood covering the dryer drums. The heat collector is preferably constituted of fabric material. The heat separately evacuated therefrom is recycled elsewhere in the plant to supply or release additional energy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Runsheng; Gao, Wenfeng; Yu, Yamei; Chen, Hua [Education Ministry Key Laboratory of Advanced Technology and Preparation for Renewable Energy Materials, Yunnan Normal University, Kunming 650092 (China)

    2009-09-15

    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 30 in China, T-type collectors should be installed with a tilt-angle about 10 less than the site latitude, whereas for H-type collectors without DFR, the reasonable tilt-angle should be about 20 less than the site latitude. Effects of some parameters on the annual collectible radiation on the collectors are also presented. (author)

  9. 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.

  10. Evacuated tubular or classical flat plate solar collectors?

    Directory of Open Access Journals (Sweden)

    Zbyslaw Pluta

    2011-01-01

    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.

  11. Modelling of Microclimate in collectors

    DEFF Research Database (Denmark)

    Holck, Ole

    1996-01-01

    Abstract It is important to avoid condensation in solar collectors, most of all because wetness of the absorber can damage the selective surface and cause corrosion on the absorber plate. During night time the cover of collectors will cool below ambient temperature due to thermal radiation to the cold sky. In climates where the air during night time becomes saturated with humidity (the relative humidity is 100%), condensation will form on the outside and inside of the collector glazing. If too m...

  12. Super radiant free electron laser in the Raman regime

    International Nuclear Information System (INIS)

    Time dependent free electron laser equations are used to analyze the super radiant emission. The space charge term is expressed in a closed form in terms of the synchrotron phase. The relevant variables are linearized so that the final equations are solved by Laplace transform which yields a steady state solution and a super radiant solution. The space charge term leads to a cosine square modulation of the super radiant intensity along the electron beam. (author). 13 refs

  13. Use of local convective and radiant cooling at warm environment

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Krejcirikova, Barbora; Kaczmarczyk, Jan; Duszyk, Marcin; Sakoi, Tomonori

    2012-01-01

    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...

  14. Parameters effect analysis of a photovoltaic thermal collector: Case study for climatic conditions of Monastir, Tunisia

    International Nuclear Information System (INIS)

    Highlights: • A photovoltaic thermal solar collector has been proposed and modeled. • The effects of meteorological, design and optical parameters have been evaluated. • A comparative economic analysis between different collectors has been conducted. - Abstract: PV/T solar collector is an energy system designed to provide both thermal and electrical energies at the same time. In this paper, the dynamic simulation of a photovoltaic thermal collector is presented. The effect of different parameters, such as meteorological, design and optical parameters are investigated. Furthermore, evaluation and comparative economic analyses among different designs of PV/T sheet-tube collectors, conventional thermal solar collector and PV module is conducted under Monastir (Tunisia) climatic conditions. Numerical results show that the thermal and electrical efficiencies significantly depend on the studied parameters. It is also found that, in terms of economy, the uncovered PV/T collector yield the best performance among others

  15. High-performance solar collector

    Science.gov (United States)

    Beekley, D. C.; Mather, G. R., Jr.

    1979-01-01

    Evacuated all-glass concentric tube collector using air or liquid transfer mediums is very efficient at high temperatures. Collector can directly drive existing heating systems that are presently driven by fossil fuel with relative ease of conversion and less expense than installation of complete solar heating systems.

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

    DEFF Research Database (Denmark)

    Bava, Federico; Furbo, Simon

    2015-01-01

    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.

  17. Colored solar collectors - Annual report 2006

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-12-15

    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)

  18. PERFORMANCE EVALUATION OF SOLAR COLLECTORS USING A SOLAR SIMULATOR

    Directory of Open Access Journals (Sweden)

    M. Norhafana

    2015-11-01

    Full Text Available Solar water heating systems is one of the applications of solar energy. One of the components of a solar water heating system is a solar collector that consists of an absorber. The performance of the solar water heating system depends on the absorber in the solar collector. In countries with unsuitable weather conditions, the indoor testing of solar collectors with the use of a solar simulator is preferred. Thus, this study is conducted to use a multilayered absorber in the solar collector of a solar water heating system as well as to evaluate the performance of the solar collector in terms of useful heat of the multilayered absorber using the multidirectional ability of a solar simulator at several values of solar radiation. It is operated at three variables of solar radiation of 400 W/m2, 550 W/m2 and 700 W/m2 and using three different positions of angles at 0º, 45º and 90º. The results show that the multilayer absorber in the solar collector is only able to best adapt at 45° of solar simulator with different values of radiation intensity. At this angle the maximum values of useful heat and temperature difference are achieved. KEYWORDS: solar water heating system; solar collector; multilayered absorber; solar simulator; solar radiation 

  19. Short-Term Solar Collector Power Forecasting

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik

    2011-01-01

    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.

  20. A Self-Biasing Pulsed Depressed Collector

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-29

    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)

  1. Biobriefcase aerosol collector

    Science.gov (United States)

    Bell, Perry M. (Tracy, CA); Christian, Allen T. (Madison, WI); Bailey, Christopher G. (Pleasanton, CA); Willis, Ladona (Manteca, CA); Masquelier, Donald A. (Tracy, CA); Nasarabadi, Shanavaz L. (Livermore, CA)

    2009-09-22

    A system for sampling air and collecting particles entrained in the air that potentially include bioagents. The system comprises providing a receiving surface, directing a liquid to the receiving surface and producing a liquid surface. Collecting samples of the air and directing the samples of air so that the samples of air with particles entrained in the air impact the liquid surface. The particles potentially including bioagents become captured in the liquid. The air with particles entrained in the air impacts the liquid surface with sufficient velocity to entrain the particles into the liquid but cause minor turbulence. The liquid surface has a surface tension and the collector samples the air and directs the air to the liquid surface so that the air with particles entrained in the air impacts the liquid surface with sufficient velocity to entrain the particles into the liquid, but cause minor turbulence on the surface resulting in insignificant evaporation of the liquid.

  2. Advanced evacuated tube collectors

    Science.gov (United States)

    Schertz, W. W.; Hull, J. R.; Winston, R.; Ogallagher, J.

    1985-04-01

    The essence of the design concept for these new collectors is the integration of moderate levels of nonimaging concentration inside the evacuated tube itself. This permanently protects the reflection surfaces and allows the use of highly reflecting front surface mirrors with reflectances greater than 95%. Previous fabrication and long term testing of a proof-of-concept prototype has established the technical success of the concept. Present work is directed toward the development of a manufacturable unit that will be suitable for the widest possible range of applications. Design alternatives include scaling up the original prototype's tube diameter from 5 cm to 10 cm, using an internal shaped metal concentrating reflector, using a variety of profile shapes to minimize so-called gap losses and accommodate both single ended and double-ended flow geometries, and allowing the use of heat pipes for the absorber tube.

  3. Inflatable solar collector

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, J.; Sylla, L.

    1984-02-21

    A solar collector comprises an upper transparent flexible cover and a lower reflectively metallized sheet, the upper cover and the lower sheet both being flexible and the space between them being inflated under gas pressure. The joint between the upper and lower members is closed by longitudinal stringers that are carried by upright side walls that protect the lower sheet against deformation by the force of the wind. Tubes carrying the liquid to be heated are disposed within the inflated enclosure, the sun's rays being concentrated on them by the reflective coating on the lower sheet; and these tubes are appropriately moved so as to follow the focal point of the lower reflector as the reflector and the sun move relative to each other during the day.

  4. LHCb Tag Collector

    Science.gov (United States)

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

    2011-12-01

    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.

  5. Solar collector wall with active curtain system; Lasikatteinen massiivienen aurinkokeraeaejaeseinae

    Energy Technology Data Exchange (ETDEWEB)

    Ojanen, T.; Heimonen, I. [VTT Building Technology, Espoo (Finland). Building Physics, Building Services and Fire Technology

    1998-12-01

    Integration of solar collector into the building envelope structure brings many advantages. The disadvantage of a passive solar collector wall is that its thermal performance can not be controlled, which may cause temporary overheating and low thermal efficiency of the collector. The thermal performance of the collector wall can be improved by using controllable, active collector systems. In this paper a solar collector wall with a controllable curtain between the transparent and absorption layers is investigated. The curtain is made of several low-emissivity foil layers, which ensures low radiation heat transfer through the curtain. The curtain decreases the heat losses out from the collector wall and it improves the U-value of the wall. The curtain is used when the solar radiation intensity to the wall is not high enough or when the wall needs protection against overheating during warm weather conditions. The materials and building components used in the collector wall, except those of the curtain, are ordinary in buildings. The transparent layer can be made by using normal glazing technology and the thermal storage layer can be made out of brick or similar material. The solar energy gains through the glazing can be utilised better than in passive systems, because the curtain provides the wall with high thermal resistance outside the solar radiation periods. The thermal performance of the collector wall was studied experimentally using a Hot-Box apparatus equipped with a solar lamp. Numerical simulations were carried out to study the yearly performance of the collector wall under real climate conditions. The objectives were to determine the thermal performance of the collector wall and to study how to optimise the use of solar radiation in this system. When the curtain with high thermal resistance is used actively, the temperature level of the thermal storage layer in the wall is relatively high also during dark periods and the heat losses out from the storage layer remain low after the solar radiation period. Thus a significant proportion of the solar radiation energy received at the absorption surface can be transferred into the room space. The delay between the solar radiation peak and the heat flow into the room can be optimised by selecting suitable materials and dimensions for the storage layer of the wall. During cold period, when there is high solar radiation to a south facing wall in successive days, the temperature of a one brick thick storage layer remains above the room air temperature throughout the day, and the collector wall operates continually as a heat radiator. (orig.) 14 refs. RAKET Research Programme

  6. A RADIANT AIR-CONDITIONING SYSTEM USING SOLAR-DRIVEN

    Directory of Open Access Journals (Sweden)

    S. A. ABDALLA

    2006-12-01

    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.

  7. Thermal Evaluation of a Solarus PV-T collector

    OpenAIRE

    Haddi, Jihad

    2013-01-01

    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 ...

  8. AEROSOL PARTICLE COLLECTOR DESIGN STUDY

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Richard Dimenna, R

    2007-09-27

    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.

  9. Accelerated Testing of Solar Collector Durability

    DEFF Research Database (Denmark)

    Svendsen, Sv Aa Højgaard

    1996-01-01

    A climatic simulator has been build to test the reliability and durability of solar collectors. In the climatic simulator the collector is expåosed to extreme climatic conditions and temperature variations in an accelerated way and during this process the function of the collector is tested and the microclimate in the collector box is measured.

  10. Phase-Change Thermal Energy Storage

    Science.gov (United States)

    1989-11-01

    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.

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

    OpenAIRE

    Scartezzini, Jean-Louis; Joly, Martin; Antonetti, Yann; Python, Martin; Gonzalez, Marina; Gascou, Thomas; Hessler, Aïcha; Schueler, Andreas

    2013-01-01

    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...

  12. Design package for concentrating solar collector panels

    Energy Technology Data Exchange (ETDEWEB)

    1978-08-01

    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.

  13. Design package for concentrating solar collector panels

    Science.gov (United States)

    1978-01-01

    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 collector is a water/glycol/working fluid type, with a dipped galvanized steel housing, transparent acrylic Fresnel lens cover, copper absorber tube, and fiber glass insulation. It weights 98 pounds. A collector assembly includes four collector units within a tracking mount array.

  14. Improved Collectors for High Power Gyrotrons

    Energy Technology Data Exchange (ETDEWEB)

    R. Lawrence Ives, Amarjit Singh, Michael Read, Philipp Borchard, Jeff Neilson

    2009-05-20

    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.

  15. Shape Control of Solar Collectors Using Shape Memory Alloy Actuators

    Science.gov (United States)

    Lobitz, D. W.; Grossman, J. W.; Allen, J. J.; Rice, T. M.; Liang, C.; Davidson, F. M.

    1996-01-01

    Solar collectors that are focused on a central receiver are designed with a mechanism for defocusing the collector or disabling it by turning it out of the path of the sun's rays. This is required to avoid damaging the receiver during periods of inoperability. In either of these two cases a fail-safe operation is very desirable where during power outages the collector passively goes to its defocused or deactivated state. This paper is principally concerned with focusing and defocusing the collector in a fail-safe manner using shape memory alloy actuators. Shape memory alloys are well suited to this application in that once calibrated the actuators can be operated in an on/off mode using a minimal amount of electric power. Also, in contrast to other smart materials that were investigated for this application, shape memory alloys are capable of providing enough stroke at the appropriate force levels to focus the collector. Design and analysis details presented, along with comparisons to test data taken from an actual prototype, demonstrate that the collector can be repeatedly focused and defocused within accuracies required by typical solar energy systems. In this paper the design, analysis and testing of a solar collector which is deformed into its desired shape by shape memory alloy actuators is presented. Computations indicate collector shapes much closer to spherical and with smaller focal lengths can be achieved by moving the actuators inward to a radius of approximately 6 inches. This would require actuators with considerably more stroke and some alternate SMA actuators are currently under consideration. Whatever SMA actuator is finally chosen for this application, repeatability and fatigue tests will be required to investigate the long term performance of the actuator.

  16. Assessment of musculoskeletal load in refuse collectors

    Directory of Open Access Journals (Sweden)

    Zbigniew W. Jó?wiak

    2013-08-01

    Full Text Available Background: The aim of this work was to assess the load on the musculoskeletal system and its effects in the collectors of solid refuse. The rationale behind this study was to formulate proposals how to reduce excessive musculoskeletal load in this group of workers. Material and Methods: The study group comprised 15 refuse collectors aged 25 to 50 years. Data about the workplace characteristics and subjective complaints of workers were collected by the free interview and questionnaire. During the survey the photorecording of the workpostures, the distance and velocity by GPS recorders, measurements of forces necessary to move containers, energy expenditure (lung ventilation method, workload estimation using the Firstbeat system and REBA method and stadiometry were done. Results: The distance walked daily by the collectors operating in terms of 2 to 3 in urban areas was about 15 km, and in rural areas about 18 km. The most frequent musculoskeletal complaints concerned the feet (60% subjects, knees, wrists and shoulders (over 40% subjects. After work-shift all examined workers had vertebral column shorter by 10 to 14 mm (11.4 mm mean. Conclusions: The results of our study show that the refuse collectors are subjected to a very high physical load because of the work organization and the way it is performed. To avoid adverse health effects and overload it is necessary to undertake ergonomic interventions, involving training of workers to improve the way of their job performance, active and passive leisure, technical control of the equipment and refuse containers, as well as the renegotiation of contracts with clients, especially those concerning non-standard containers. Med Pr 2013;64(4:507–519

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

    Directory of Open Access Journals (Sweden)

    Lívia Bodonská

    2006-09-01

    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

  18. 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)

  19. Combined solar collector and storage systems

    International Nuclear Information System (INIS)

    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

  20. Thermophotovoltaics for Combined Heat and Power Using Low NOx Gas Fired Radiant Tube Burners

    Science.gov (United States)

    Fraas, Lewis; Avery, James; Malfa, Enrico; Wuenning, Joachim G.; Kovacik, Gary; Astle, Chris

    2003-01-01

    Three new developments have now occurred, making economical TPV systems possible. The first development is the diffused junction GaSb cell that responds out to 1.8 microns producing over 1 W/cm2 electric, given a blackbody IR emitter temperature of 1250 C. This high power density along with a simple diffused junction cell makes an array cost of 0.50 per Watt possible. The second development is new IR emitters and filters that put 75% of the radiant energy in the cell convertible band. The third development is a set of commercially available ceramic radiant tube burners that operate at up to 1250 C. Herein, we present near term and longer term spectral control designs leading to a 1.5 kW TPV generator / furnace incorporating these new features. This TPV generator / furnace is designed to replace the residential furnace for combined heat and power for the home.

  1. Suspended radiant cooling system with thermally activated concrete ceiling; Kuehldeckensystem mit Aktivierung der Speichermasse der Betondecke

    Energy Technology Data Exchange (ETDEWEB)

    Nuessle, Fritz [ZENT-FRENGER Gesellschaft fuer Gebaeudetechnik mbH, Heppenheim (Germany); Pfafferott, Jens [Fraunhofer-Institut fuer Solare Energiesysteme, Freiburg (Germany)

    2011-02-15

    Office buildings are heated and cooled by thermoactive building systems for many years. These energy efficient heating and cooling concepts provide excellent thermal comfort. The first systems were installed as suspended cooling ceilings which are applied all-over Europe and go along with a high user satisfaction. Another widely adopted construction principle is the concrete conditioning. Monitoring campaigns in energy efficient office buildings show clearly that radiant systems can be successfully operated for both cooling and heating. Although both the radiant ceiling and the concrete core conditioning use the same long-wave radiative heat transfer the operation is different due to the thermal storage effect. Architects and HVAC planners have to decide for one of these solutions based on the pros and cons for each system. This article presents a hybrid form which can be used for new buildings and refurbishment projects. Laboratory measurements in a thermally heavy test chamber prove the thermal performance of a double-sided suspended radiant panel in interaction with the concrete ceiling. (Copyright copyright 2011 Ernst and Sohn Verlag fuer Architektur und technische Wissenschaften GmbH and Co. KG, Berlin)

  2. Radiant heat testing of the H1224A shipping/storage container

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-05-01

    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.

  3. Development and investment of solar collectors for conversion of solar radiation into heat and/or electricity

    International Nuclear Information System (INIS)

    This article describes work on two projects of the National Energy Efficiency Program NEEP 709300036 and NEEP 271003 titled The Model of Solar Collector for Middle Temperature Conversion of Solar Radiation on Heat, and Development and Investigation on Hybrid Solar Collector for Heat and Electricity Generation, respectively. This first project deals with solar collector that transfer solar radiation in heat in area of middle temperature conversion (at temperature above 100 deg C). During entire year it can realize significant saving of electric energy used for preparation of warm water and in central and district heating. During work on the second project, two hybrid solar collectors, their installation, mathematical model, software, and experimental set-up were designed and realized. The first collector had the photovoltaic panel located above the absorber and the second collector had the panel located on the absorber. For both collectors, the results show that efficiency of fossil fuel replacement is 85%

  4. 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.

  5. Installation package for concentrating solar collector panels

    Science.gov (United States)

    1978-01-01

    The concentrating solar collector panels comprise a complete package array consisting of collector panels using modified Fresnel prismatic lenses for a 10 to 1 concentrating ratio, supporting framework, fluid manifolding and tracking drive system, and unassembled components for field erection.

  6. 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 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)

  7. 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

  8. A solar collector design procedure for crop drying

    Scientific Electronic Library Online (English)

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

    2005-06-01

    Full Text Available 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.

  9. Automated Verification of Practical Garbage Collectors

    OpenAIRE

    Hawblitzel, Chris; Petrank, Erez

    2010-01-01

    Garbage collectors are notoriously hard to verify, due to their low-level interaction with the underlying system and the general difficulty in reasoning about reachability in graphs. Several papers have presented verified collectors, but either the proofs were hand-written or the collectors were too simplistic to use on practical applications. In this work, we present two mechanically verified garbage collectors, both practical enough to use for real-world C# benchmarks. The...

  10. The radiant component of steam heat conductivity at high pressures and temperatures

    Science.gov (United States)

    Panchenko, S. V.; Dli, M. I.; Borisov, V. V.

    2015-07-01

    The problem of energy transfer by heat conduction and radiation is brought to a differential equation containing temperature derivatives at the boundaries and based on the selectively gray approximation of absorbing medium. A method for analytically solving the linearized problem radiant-conductive heat transfer in a flat layer of selectively absorbing medium is proposed, using which an unsymmetrical temperature profile more accurately approximating the experimental results can be obtained. The adequacy of the solution method is demonstrated by comparing the calculation results with the experimental and the results obtained using numerical methods. The effect the intermolecular interactions have on the optical properties of highly compressed media is analyzed. A dependence for determining the integral intensity of steam bands at pressures of up to 100 MPa is obtained. Quite satisfactory agreement is obtained between the calculated values of absorption intensities at increased pressures, including those for steam. The radiant component values obtained from steam heat conductivity measurements carried out in a wide range of temperatures taking into account the absorption selectivity and deviation of heat conductivity coefficients with absorption and for a transparent gas model are presented. The study results can be used for estimating the radiant component in heat conductivity measurements of absorbing fluids.

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

    DEFF Research Database (Denmark)

    Le Dréau, J.; Heiselberg, P.

    2014-01-01

    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.

  12. Performance of cylindrical plastic solar collectors for air heating

    International Nuclear Information System (INIS)

    Highlights: • The study including the combined convective and radiative heat transfer analysis. • The solar collector is manufactured from LDPE films acting as a black absorber. • Comparisons between the experimental data and the theoretical methods have been made. • The thermal efficiency increases with decreasing the major axes of elliptic shape. • The Nusselt number between the absorber and the heated air is determined. - Abstract: A theoretical and experimental study including the combined convective and radiative heat transfer analysis of a flexible cylindrical type solar air-heater for agriculture crops dehydration as well as heating processes is presented. The solar collector is manufactured from LDPE films acting as a black absorber with a back insulation and double transparent covers sealed together along its edges. The collector is to be blown with a flow of pressurized air. The experiments are carried out with solar collectors of circular shapes having 0.5 m diameter and solar collectors of elliptic shapes having 0.55 m and 0.65 m major axis. Energy balance of the cover, absorber and air yield three simultaneous quadratic algebraic equations in the three unknowns namely, cover, absorber and outlet air temperatures. A computer program is written for calculating the outlet temperature using the Newton–Raphson method and the collector thermal efficiency in terms of its diameter, length, mass flow rate, inlet temperature and solar insolation. Moreover the Nusselt number between the absorber and the heated air is determined experimentally in relation with the Reynolds number. Comparisons between the experimental data and the theoretical methods for the collector efficiency demonstrate a good agreement. In addition of this, the present experimental results of Nusselt number are correlated and compared with a correlation of another authors

  13. Experimental investigation of tri-functional photovoltaic/thermal solar collector

    International Nuclear Information System (INIS)

    Highlights: • A design of tri-functional photovoltaic/thermal solar collector is proposed. • The performance of tri-functional PV/T collector is investigated and compared. • The tri-functional PV/T collector is flexible to different working modes and variable seasons. - Abstract: Photovoltaic/thermal (PV/T) solar collectors can provide electric power and thermal energy simultaneously. Either PV/T water collectors or PV/T air collectors can be left unused in some seasons because of the freezing problem of water and seasonal demand of hot air. In this paper, a novel design of tri-functional PV/T solar collector was proposed. The collector can work in PV/water-heating mode or PV/air-heating mode according to the seasonal requirements. Experiments were conducted in different working modes under variable conditions to evaluate the performance of collector. The results show that the daily thermal efficiency achieved 46.0% with the electrical efficiency of 10.2% in PV/air-heating mode. The temperature increase of air reached 20 °C with the flow rate of 0.033 kg/s on a sunny day. The instantaneously thermal efficiency at zero reduced temperature were 37.4% and 44.3% as the air flow rate was 0.026 kg/s and 0.032 kg/s respectively. In PV/water-heating mode, the thermal efficiency of the collector was 56.6% at zero reduced temperature, and the daily thermal efficiency of the system was around 36.0%. Compared with solar collectors presented by other authors, the tri-functional PV/T collector is able to operate efficiently in various conditions

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

    OpenAIRE

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

    2011-01-01

    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...

  15. Entropy generation in a solar collector filled with a radiative participating gas

    International Nuclear Information System (INIS)

    Heat losses in solar energy collectors are associated with thermodynamic irreversibility, which causes entropy generation. These losses can be reduced through EGM (entropy generation minimization) techniques. Using computational fluid dynamics, entropy generation associated with viscous dissipation, heat conduction and convection, and thermal radiation is studied for a solar collector filled with a radiative participating gas. The EGM methodology shows that gas filled solar collectors have an optimum optical thickness and an optimum tilt angle where the heat losses are minimized. These optimum conditions for gas filled collectors cannot accurately be determined using conventional performance parameters. Solar collectors filled with radiative participating gases are also found to be suitable for the tropics. - Highlights: • Thermal losses in solar collectors are assessed using the 2nd law analysis method. • Near-wall zones are identified as critical regions in solar collectors. • Radiative entropy generation is found to be important in gas-filled solar collectors. • Optimum optical thickness and tilt are determined for gas-filled collectors

  16. Simulations of geometry effects and loss mechanisms affecting the photon collection in photovoltaic fluorescent collectors

    Directory of Open Access Journals (Sweden)

    Rau U.

    2012-06-01

    Full Text Available Monte-Carlo simulations analyze the photon collection in photovoltaic systems with fluorescent collectors. We compare two collector geometries: the classical setup with solar cells mounted at each collector side and solar cells covering the collector back surface. For small ratios of collector length and thickness, the collection probability of photons is equally high in systems with solar cells mounted on the sides or at the bottom of the collector. We apply a photonic band stop filter acting as an energy selective filter which prevents photons emitted by the dye from leaving the collector. We find that the application of such a filter allows covering only 1% of the collector side or bottom area with solar cells. Furthermore, we compare ideal systems in their radiative limits to systems with included loss mechanisms in the dye, at the mirror, or the photonic filter. Examining loss mechanisms in photovoltaic systems with fluorescent collectors enables us to estimate quality limitations of the used materials and components.

  17. DT results of TFTR's alpha collector

    International Nuclear Information System (INIS)

    An escaping alpha collector probe has been developed for TFTR's DT phase to complement the results of the lost alpha scintillator detectors which have been operating on TFTR since 1988. Measurements of the energy distribution of escaping alphas have been made by measuring the range of alphas implanted into nickel foils located within the alpha collector. Exposed samples have been analyzed for 4 DT plasma discharges at plasma currents of 1.0 and 1.8 MA. The results at 1.0 MA are in good agreement with predictions for first orbit alpha loss at 3.5 MeV. The 1.8 MA results, however, indicate a large anomalous loss of partially thermalized alphas at an energy ?30% below the birth energy and at a total fluence nearly an order of magnitude above expected first orbit loss. This anomalous loss is not observed with the lost alpha scintillator detectors in DT plasmas but does resemble the anomalous delayed loss seen in DD plasmas. Several potential explanations for this loss process are examined. None of the candidate explanations proposed thus far are fully consistent with the anomalous loss observations

  18. Validation of the uncertainty budget for soft X-ray radiant power measurement using a cryogenic radiometer

    CERN Document Server

    Rabus, H; Scholze, F; Thornagel, R; Ulm, G

    2002-01-01

    The cryogenic radiometer SYRES, a thermal detector based on the electrical substitution principle, has been used as the primary detector standard for radiant power measurement in the ultraviolet, vacuum ultraviolet and soft X-ray spectral ranges. In order to investigate the possibility of radiant energy being deposited in its absorber cavity without being transformed into heat when detecting soft X-rays, SYRES has been directly compared with the electron storage ring BESSY 1, a primary radiometric source standard of calculable spectral radiant power. To this end, the integral radiant power emitted by the storage ring,into a solid angle defined by a high-precision aperture was measured with SYRES. The experiments were conducted at two nominal energies of the circulating electrons, 800 MeV and 340 MeV, to study the influence of the different spectral distributions of the synchrotron radiation. For the original graphite-coated cavity absorber, significant discrepancies were found which could be traced back to th...

  19. Radiant{trademark} Liquid Radioisotope Intravascular Radiation Therapy System

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-01-16

    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.

  20. Use of local convective and radiant cooling at warm environment

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Krejcirikova, Barbora

    2012-01-01

    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.

  1. Design Support System for Parabolic Trough Solar Collector

    Directory of Open Access Journals (Sweden)

    Abraham D. Woldeyohannes

    2012-01-01

    Full Text Available 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 are available in the market, they are either expensive or limited to certain types of solar collectors. This study presents an in-house design simulation software for parabolic trough collector. The simulation software was coded in Microsoft Visual Studio.Net 2010. Through its Graphical User Interface (GUI, the software allows the user to give input parameters, explore built in standards and review outputs. The output parameters include geometric design parameters, heat losses coefficient and efficiencies. The output parameters are important in the initial stage of designing parabolic trough collectors to reduce design time and effort. The results of the simulation software are validated with published experimental and analytical results.

  2. 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

  3. IEA/SPS 500 kW distributed collector system

    Science.gov (United States)

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

    1980-05-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Ajay Vardhan

    2013-10-01

    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.

  5. Automated Verification of Practical Garbage Collectors

    CERN Document Server

    Hawblitzel, Chris

    2010-01-01

    Garbage collectors are notoriously hard to verify, due to their low-level interaction with the underlying system and the general difficulty in reasoning about reachability in graphs. Several papers have presented verified collectors, but either the proofs were hand-written or the collectors were too simplistic to use on practical applications. In this work, we present two mechanically verified garbage collectors, both practical enough to use for real-world C# benchmarks. The collectors and their associated allocators consist of x86 assembly language instructions and macro instructions, annotated with preconditions, postconditions, invariants, and assertions. We used the Boogie verification generator and the Z3 automated theorem prover to verify this assembly language code mechanically. We provide measurements comparing the performance of the verified collector with that of the standard Bartok collectors on off-the-shelf C# benchmarks, demonstrating their competitiveness.

  6. Inverse Marx modulators for self-biasing klystron depressed collectors

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Mark A; /SLAC

    2014-07-31

    A novel pulsed depressed collector biasing scheme is proposed. This topology feeds forward energy recovered during one RF pulse for use on the following RF pulse. The presented ''inverse'' Marx charges biasing capacitors in series, and discharges them in parallel. Simulations are shown along with experimental demonstration on a 62kW klystron.

  7. Engineering of solar photocatalytic collectors

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, S.M.; Galvez, J.B.; Rubio, M.I.M.; Ibanez, P.F.; Padilla, D.A. [Plataforma Solar de Almeria (CIEMAT) (Spain); Pereira, M.C.; Mendes, J.F. [Instituto Nacional de Engenharia e Tecnologica Industrial, Lisbon (Portugal); Correia de Oliveira, J. [Aosol Energias Renovaveis Lda, Porto Alto (Portugal)

    2004-11-01

    This paper briefly describes the different collectors used in solar photocatalysis for wastewater treatment and, based on prior experience, the main advantages and disadvantages of each. As the tubular-shape reactor configuration is the most appropriate for handling and pumping water, the compound parabolic collector (CPC) is proposed as an interesting combination of parabolic concentrators and flat static systems and constitutes a good option for solar photochemical applications. The design of compound parabolic concentrators for solar photocatalytic applications is described in detail and 25-50 mm is proposed as the optimum photoreactor diameter, based on the optical characteristics and optimum concentration of the two photocatalytic systems (TiO{sub 2} and photo-Fenton) that can be used with sunlight for wastewater treatment. It has been demonstrated that since aluminium is the only metal that is highly reflective in the ultraviolet spectrum of solar radiation, aluminium-based mirrors are the best option. But, especially when exposed to outdoor conditions, aluminium must be protected and, therefore, at the present time, anodised and electropolished aluminium surfaces are considered the most suitable solutions. As the photochemical reactor contain the working fluid, including the catalyst, it must transmit UV sunlight efficiently and be able to work under enough pressure to handle the high volumes resulting from the large number of collectors in an industrial treatment plant, only low-iron glass is proposed as feasible for constructing the photoreactor (collector absorbers). Finally, ray-tracing algorithm simulations are presented as a design tool for the optical configuration of a particular reactor, drawing conclusions for its improvement and assisting in final engineering decision-making. (Author)

  8. Dual axis solar collector assembly

    Energy Technology Data Exchange (ETDEWEB)

    Eiden, G.E.

    1991-02-19

    This patent describes a solar collector. It comprises: an elongate main boom having a longitudinal axis; a solar collector frame first mounting means for pivotally mounting the solar collector frame to the main boom for pivotal motion about first pivotal axis substantially parallel to the longitudinal axis of the main boom; and first motor means, separate from the first mounting means a generally horizontal countertop mounted on the frame means adapted for a placement and retention of an ostomy bag thereon during cleaning of the ostomy bag. The countertop having a sink formed therein for draining liquid and waste materials from the ostomy bag and from the countertop; a mirror mounted upright on the frame means; a light source mounted to the frame means for illuminating the countertop, a user and the mirror; and a drainage conduit, having a first end connected to the sink, the drainage conduit being adapted for carrying the waste materials and the liquid from the sink to the disposal location.

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

    Directory of Open Access Journals (Sweden)

    Lal Kundan

    2013-04-01

    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

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    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 bui...

  11. A method for rating and sizing solar collectors in residential heating systems

    Energy Technology Data Exchange (ETDEWEB)

    Hollands, K.G.F.; Chinneck, J.W.; Chandrashekar, M

    1977-01-01

    A collector figure-of-merit is developed which evaluates the year-round performance of a flat plate solar collector used in residential heating systems at a particular location. Using this concept, a simplified method of collector sizing is developed. An economic figure-of-merit is also postulated. In order to evaluate the relevant parameters, computer simulations were carried out for eight major Canadian cities for both air and liquid-based systems, for five sets of collector specifications, for three proportions of heating done by solar energy solar fraction, and for three fractions of the total heating load due to domestic hot water. Results of the study show that the solar fraction is the most important variable in determining a collector's yearly performance. An index is developed denoting the difficulty of heating by solar methods in a given location. 9 refs., 5 figs., 56 tabs.

  12. The implementation of the regulations on solar collectors in buildings

    OpenAIRE

    Abreu, Isabel; Oliveira, Rui

    2008-01-01

    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...

  13. Calculation of the top loss coefficient of a flat-plate collector

    Science.gov (United States)

    Agarwal, V. K.; Larson, D. C.

    1981-01-01

    The useful energy gain of a flat plate collector depends strongly on energy losses due to convective and radiative heat transfer processes from the top surface of the collector. Klein's (1975) empirical equations are given, discussed, and compared at different plate temperatures for calculations of a simpler equation for a top loss coefficient. Results show Klein's approach as satisfactory, although discrepancies arose when testing for the coefficient's dependence on collector tilt. In addition, the new equation proved simpler to manipulate, and provided an enhanced accuracy in the calculations over a wide range of different parameters.

  14. Load and Season Adapted Solar Collectors

    OpenAIRE

    Nordlander, Svante; Rönnelid, Mats; Karlsson, Björn

    2000-01-01

    In Sweden solar irradiation and space heating loads are unevenly distributed over the year. Domestic hot water loads may be nearly constant. Test results on solar collector performance are often reported as yearly output of a certain collector at fixed temperatures, e g 25, 50 and 75 C. These data are not suitable for dimensioning of solar systems, because the actual performance of the collector depends heavily on solar fraction and load distribution over the year.At higher latitudes it is di...

  15. Electrostatic collector’s field investigations with the help of electronic probe

    Directory of Open Access Journals (Sweden)

    ?. V. Derenovsky

    1966-12-01

    Full Text Available In this article the possibility of practical use of probe beam method is considered. I t ’s shown how to find out space charge field distribution in microwave tubes collectors using results of probe beam measurements of investigated space of the collectors cross-sections. Such investigations are necessary in special collector system design for microwave tubes of high efficiency.

  16. Performance and cost benefits analysis of double-pass solar collector with and without fins

    International Nuclear Information System (INIS)

    Highlights: • The thermal performances and cost analysis of the double-pass solar collector with and without fins absorber were discussed. • The theoretical and experimental study on the double-pass solar air collector with and without fins absorber was conducted. • The ratio of AC/AEG or the cost benefit ratio was presented. • The double-pass solar collector with fins absorber is more cost-effective compared to without fins absorber. - Abstract: The performance and cost benefit analysis of double-pass solar collector with and without fins have been conducted. The theoretical model using steady state analysis has been developed and compared with the experimental results. The performance curves of the double-pass solar collector with and without fins, which included the effects of mass flow rate and solar intensity on the thermal efficiency of the solar collector, were obtained. Results indicated that the thermal efficiency is proportional to the solar intensity at a specific mass flow rate. The thermal efficiency increased by 9% at a solar intensity of 425–790 W/m2 and mass flow rate of 0.09 kg/s. The theoretical and experimental analysis showed a similar trend as well as close agreement. Moreover, a cost-effectiveness model has been developed examine the cost benefit ratio of double-pass solar collector with and without fins. Evaluation of the annual cost (AC) and the annual energy gain (AEG) of the collector were also performed. The results show that the double-pass solar collector with fins is more cost-effective compared to the double-pass solar collector without fins for mass flow rate of 0.01–0.07 kg/s. Also, simulations were obtained for the double-pass solar collector with fins at Nusselt number of 5.42–36.21. The energy efficiency of collector increases with the increase of Nusselt number. The results show that by increasing the Nusselt number simultaneously would drop the outlet temperature at any solar intensity. Increase in Nusselt number causes an increase in energy efficiency. On the other hand, the exergy efficiency has been obtained, which the fluctuation of exergy efficiency was based on the Nusselt number, collector length and solar intensity level

  17. THE COLLECTOR - A FREUDIAN INTERPRETATION

    OpenAIRE

    Korošec, Valerija

    2013-01-01

    The purpose of this diploma seminar is to give an in-depth Freudian reading of the novel The Collector by John Fowles and apply basic Freudian psychoanalytic concepts to it, with the intent to analyse the main characters, the relations between them and the meaning of dreams and symbols which appear in the novel. The analysis has shown that the actions of the main character can be explained with Freud's theory of Self and other psychoanalytic concepts: the main character has been marked with t...

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

    DEFF Research Database (Denmark)

    Li, Rongling; Yoshidomi, Togo

    2015-01-01

    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.

  19. ADVANCED HYBRID PARTICULATE COLLECTOR; FINAL

    International Nuclear Information System (INIS)

    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

  20. 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 greenhouse utilization planning

  1. Low cost vee-trough evacuated tube collector module

    Science.gov (United States)

    Selcuk, M. K.

    1979-01-01

    A low cost solar collector capable of operating at 150-200 C is described. An evacuated tube receiver is combined with asymmetric vee-trough concentrators. Peak efficiencies of about 40% at 120 C and 30% at 180 C are expected. Predicted future collector cost is $70/sq m which yields an energy cost of $4.20/GJ at 120 C. During the development of the vee trough/evacuated tube collector both mathematical models to predict thermal and optical performance were developed and tests run to verify theory. The asymmetric vee trough concentrator increases the solar flux intensity for an average value of 2 for year-round performance. Optimized collector module has reflector angles of 55 deg/85 deg. The aperture plane is tilted to the latitude. The reflector is made of electropolished aluminum. The supporting frame is formed by bending sheet metal. Evacuated tube receivers are Pyrex, 15 cm diam and 2.4 m long. The module has 12 tubes on right and left sides altogether. Attainable operation at temperatures on the order of 150-200 C are suitable for absorption refrigeration and power generation via Rankine engines.

  2. Performances of Low Temperature Radiant Heating Systems

    OpenAIRE

    Boji?, Milorad; Cvetkovic, Dragan; Skerli?, Jasmina; Nikoli?, Danijela; Boyer, Harry

    2012-01-01

    Low temperature heating panel systems offer distinctive advantages in terms of thermal comfort and energy consumption, allowing work with low exergy sources. The purpose of this paper is to compare floor, wall, ceiling, and floor-ceiling panel heating systems in terms of energy, exergy and CO2 emissions. Simulation results for each of the analyzed panel system are given by its energy (the consumption of gas for heating, electricity for pumps and primary energy) and exergy co...

  3. Electrochemical Properties of Current Collector in the All-vanadium Redox Flow Battery

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Gan-Jin; Oh, Yong-Hwan; Ryu, Cheol-Hwi [Hoseo University, Asan (Korea, Republic of); Choi, Ho-Sang [Kyungil University, Gyeongsan, (Korea, Republic of)

    2014-04-15

    Two commercial carbon plates were evaluated as a current collector (bipolar plate) in the all vanadium redox-flow battery (V-RFB). The performance properties of V-RFB were test in the current density of 60 mA/cm{sup 2}. The electromotive forces (OCV at SOC 100%) of V-RFB using A and B current collector were 1.47 V and 1.54 V. The cell resistance of V-RFB using A current collector was 4.44-5.00 ?·cm{sup 2} and 3.28-3.75 ?·cm{sup 2} for charge and discharge, respectively. The cell resistance of V-RFB using B current collector was 4.19-4.42?·cm{sup 2} and 4.71-5.49?·cm{sup 2} for charge and discharge, respectively. The performance of V-RFB using each current collector was evaluated. The performance of V-RFB using A current collector was 93.1%, 76.8% and 71.4% for average current efficiency, average voltage efficiency and average energy efficiency, respectively. The performance of V-RFB using B current collector was 96.4%, 73.6% and 71.0% for average current efficiency, average voltage efficiency and average energy efficiency, respectively.

  4. Theoretical and experimental investigations of Chinese evacuated tubular solar collectors

    DEFF Research Database (Denmark)

    Qin, Lin; Furbo, Simon

    1999-01-01

    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.

  5. Optimization of dish solar collectors

    Science.gov (United States)

    Jaffe, L. D.

    1983-01-01

    Methods for optimizing parabolic dish solar collectors and the consequent effects of various optical, thermal, mechanical, and cost variables are examined. The most important performance optimization is adjusting the receiver aperture to maximize collector efficiency. Other parameters that can be adjusted to optimize efficiency include focal length, and, if a heat engine is used, the receiver temperature. The efficiency maxima associated with focal length and receiver temperature are relatively broad; it may, accordingly, be desirable to design somewhat away from the maxima. Performance optimization is sensitive to the slope and specularity errors of the concentrator. Other optical and thermal variables affecting optimization are the reflectance and blocking factor of the concentrator, the absorptance and losses of the receiver, and, if a heat engine is used, the shape of the engine efficiency versus temperature curve. Performance may sometimes be improved by use of an additional optical element (a secondary concentrator) or a receiver window if the errors of the primary concentrator are large or the receiver temperature is high. Previously announced in STAR as N83-19224

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

    DEFF Research Database (Denmark)

    Chen, Ziqian; Perers, Bengt; Furbo, Simon; Fan, Jianhua

    2013-01-01

    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 f...

  7. Evaluation of Test Method for Solar Collector Efficiency

    OpenAIRE

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

    2006-01-01

    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...

  8. Evaluation of Test Method for Solar Collector Efficiency

    DEFF Research Database (Denmark)

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

    2006-01-01

    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 approxima...

  9. The Antiproton Collector and Antiproton Accumulator

    CERN Multimedia

    1987-01-01

    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).

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Raffles Senjaya

    2008-05-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-01

    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)

  13. Theoretical and experimental investigation of plate screen mesh heat pipe solar collector

    International Nuclear Information System (INIS)

    Highlights: • Experimental and computer simulation are performed for wicked heat pipe solar collectors. • Outdoor tests are conducted to compare its performance at different period of the year. • Modest improvement of the collector is achievement by adding fins to the condenser region. • Mesh number of heat pipe porous structure is an important factor in collector design. • Water slightly outperform methanol for such design and operating conditions. - Abstract: Heat pipes are efficient heat transfer devices for solar hot water heating systems. However, the effective downward transfer of solar energy in an integrated heat pipe system provides increased design and implementation options. There is a lack of literature about flat plate wicked assisted heat pipe solar collector, especially with the presence of finned water-cooled condenser wicked heat pipes for solar energy applications. In this paper the consequence of incorporating fins arrays into the condenser region of screen mesh heat pipe solar collector is investigated. An experimental and a transient theoretical model are conducted to compare the performances of solar heating system at different period of the year. A good agreement is shown between the model and the experiment. Two working fluids are investigated (water and methanol) and results reveal that water slightly outperforms methanol with a collector instantaneous efficiency of nearly 60%. That modest improvement is achieved by adding fins to the condenser region of the heat pipes. Results show that the collector efficiency increase as the number of fins increases (upon certain number) and reveal that the mesh number is an important factor which affect the overall collector efficiency. An optimal heat pipe mesh number of 100 meshes/in. with two layers appears to be favorable in such collectors for their design and operating conditions

  14. Collector and source sheaths of a finite ion temperature plasma

    International Nuclear Information System (INIS)

    The region between a Maxwellian plasma source and an absorbing surface is described theoretically with a static, kinetic plasma--sheath model and modeled numerically with a dynamic, electrostatic particle simulation. In the kinetic theory, Poisson's equation and Vlasov equations govern the non-Maxwellian velocity distribution of the ions and electrons. The results in this paper for collector potential and plasma transport agree with the bounded model of Emmert et al. [Phys. Fluids 23, 803 (1980)]. However, this approach differs from those using traditional Bohm sheath analysis by ±0.25 (in units of electron temperature) for potential drop through the collector sheath of a hydrogen plasma. In both the theory and simulation, the plasma source injects equal fluxes of ions and electrons with half-Maxwellian velocities and various mass and temperature ratios and is assumed to have a zero electric field. The potential change within a spatially distributed, full Maxwellian source region is represented with the source sheath potential drop that depends primarily on temperature ratio. This source sheath evolves over a few Debye lengths from the source to neutralize the injected plasma. The plasma flows to an electrically floating collector where the more familiar electron-repelling collector sheath appears. The collector potential ?C and source sheath potential drop ?P (in units of electron temperature) are evaluated as a function of mass and temperature ratio. The velocity moments of density, drift velocity, temperature, kinetic energy flux, and heat flux are also derived as a function of ?C and ?P. Comparisons with electrostatic particle simulations are shown for the ion/electron mass ratios of 40 and 100 and temperature ratios of 0.1, 1, and 10

  15. 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.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-01-15

    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)

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

    Science.gov (United States)

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

    2001-12-01

    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.

  18. Mathematical modelling and sensitivity analysis of sun tracking parabolic trough solar collectors

    Energy Technology Data Exchange (ETDEWEB)

    Colak, L. [Baskent Univ., Baskent (Turkey). Dept. of Mechanical Engineering; Durmaz, A. [Gazi Univ., Ankara (Turkey). Dept. of Mechanical Engineering

    2009-06-15

    Since solar heating systems are expensive, they must be accurately sized for widespread commercialization. This paper presented a new design for parabolic trough collectors, which are known for high thermal efficiency, low cost, long life and marketability. It also presented a newly derived mathematical model for the solar beam and heat transfer mechanisms on the absorber tube of the parabolic trough solar collector. The model was verified using experimental data obtained from literature. Some simulations were performed for sensitivity analysis of the parameters that affects the design. These sensitivity analysis showed that the increase in solar radiation and reflector aperture increases the collector efficiency because of the increase in the energy collected, but the increase in absorber pipe diameter and the wind velocity decreases the collector efficiency due to the increase in heat losses. The increase in working fluid mass flow rate had almost no effect on the values larger than 0.5 kg/s. However, the collector performance increased for small angle of incidence values, indicating that a sun tracking mechanism should be used for parabolic trough type solar collectors. It was concluded that the increase in absorbtivity of absorber tube, the increase in transmissivity of glass cover and the increase in the reflectivity of the parabolic reflected surface, increases the collector efficiency due to the increase in optical efficiency. 7 refs., 3 tabs., 10 figs.

  19. Performance Evaluation of a Nanofluid-Based Direct Absorption Solar Collector with Parabolic Trough Concentrator

    Directory of Open Access Journals (Sweden)

    Guoying Xu

    2015-12-01

    Full Text Available Application of solar collectors for hot water supply, space heating, and cooling plays a significant role in reducing building energy consumption. For conventional solar collectors, solar radiation is absorbed by spectral selective coating on the collectors’ tube/plate wall. The poor durability of the coating can lead to an increased manufacturing cost and unreliability for a solar collector operated at a higher temperature. Therefore, a novel nanofluid-based direct absorption solar collector (NDASC employing uncoated collector tubes has been proposed, and its operating characteristics for medium-temperature solar collection were theoretically and experimentally studied in this paper. CuO/oil nanofluid was prepared and used as working fluid of the NDASC. The heat-transfer mechanism of the NDASC with parabolic trough concentrator was theoretically evaluated and compared with a conventional indirect absorption solar collector (IASC. The theoretical analysis results suggested that the fluid’s temperature distribution in the NDASC was much more uniform than that in the IASC, and an enhanced collection efficiency could be achieved for the NDASC operated within a preferred working temperature range. To demonstrate the feasibility of the proposed NDASC, experimental performances of an NDASC and an IASC with the same parabolic trough concentrator were furthermore evaluated and comparatively discussed.

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

    Directory of Open Access Journals (Sweden)

    Madhukeshwara. N, E. S. Prakash

    2012-01-01

    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.

  1. Radiants, orbits, spectra, and deceleration of selected 2011 Draconids.

    Czech Academy of Sciences Publication Activity Database

    Borovi?ka, Ji?í; Koten, Pavel; Shrbený, Lukáš; Štork, Rostislav; Hornoch, Kamil

    Howe : International Meteor Organization, 2013 - (Gyssens, M.), s. 65-69 ISBN 978-2-87355-024-4. [International Meteor Conference. La Palma, Canary Islands , (ES), 20.09.2012-23.09.2012] R&D Projects: GA ?R(CZ) GAP209/11/1382; GA ?R GA205/09/1302; GA ?R GPP209/11/P651 Institutional support: RVO:67985815 Keywords : Draconid meteors * radiant * orbit Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  2. 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.

  3. 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 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.

  4. Owens--Illinois liquid solar collector materials assessment

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, R. L.

    1978-03-01

    The Marshall Space Flight Center (MSFC) was requested by the Energy Research and Development Agency (ERDA) to assess the general suitability of the design and materials and to investigate certain failure modes of the Owens-Illinois (O-I) Sunpak solar energy collector system. The primary problem was the violent fracture of collector tubes, with attendant scattering of glass fragments, under boilout conditions. The data and information generated during the materials analysis segment of this effort are presented. These data were obtained during pressure testing of the individual tubes, performance testing of a complete array of tubes on the MSFC solar simulator apparatus, and in other investigations as noted. The information herein represents only the data directly associated with materials analysis and is not a comprehensive presentation of all the data compiled during the MSFC test program.

  5. Investigation of Hydraulic and Thermal Performance of Solar Collectors used for Solar Cooling

    OpenAIRE

    Badar, Abdul Waheed

    2012-01-01

    Solar cooling is an emerging technology and in a process of development to be competitive with the conventional systems generally based on electricity driven vapor compression cooling machines. Efficient performance of the solar collectors consistently over a time span of 20-25 years is the key towards achieving the required primary energy savings and cost benefits. The present research work investigates various thermal and hydraulic aspects of the solar collectors used for a solar cooling ap...

  6. An oriented-design simplified model for the efficiency of a flat plate solar air collector

    OpenAIRE

    Luna, David; Jannot, Yves; Nadeau, Jean-Pierre

    2010-01-01

    Abstract In systems design, suitably adapted physical models are required. Different modelling approaches for a solar air collector were studied in this paper. First, a classical model was produced, based on a linearization of the conservation of energy equations. Its resolution used traditional matrix methods. In order to improve the possibilities for use in design, the behaviour of the collector was next expressed in terms of efficiency. Lastly, simplified models constructed from...

  7. 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.

  8. Single-stage depressed collectors for gyrotrons

    International Nuclear Information System (INIS)

    Two 140 GHz gyrotrons with a single-step depressed collector have been operated. The different position of the isolating collector gap in the stray magnetic field causes the electron motion in the retarding region to be in one case adiabatic and in the other case nonadiabatic. The kind of motion within the retarding field influences strongly the behavior of the gyrotron with a depressed collector. In the case of nonadiabatic motion a significant amount of transverse momentum is given to the electrons reflected at the collector potential. This causes the reflected electrons to be trapped between the magnetic mirror and the collector. The electrons escape from the trap by diffusion across the magnetic field to the body of the tube thus contributing to the body current. Despite the high body current there is no observable influence of the collector voltage on the RF output power. In the case of adiabatic motion the reflected electrons do not gain a sufficient amount of transverse momentum to be trapped by the magnetic mirror. They pass the cavity toward the gun and they are trapped between the negative gun potential and the collector. The interaction with the RF field by electrons traveling through the cavity enhances the diffusion in the velocity space thus enabling the trapped electrons to overcome the potential barrier and escape toward the collector. Therefore the body current stays at low values since in this case the reflected electrons do not contribute to it. However, at higher collector voltages a reduction of RF power occurred and some noise in the electron beam was observed. The main motivation for the development of gyrotrons in the frequency range above 100 GHz with power levels in excess of several hundreds kW per tube, is the application in magnetic fusion devices for plasma heating and for electron current drive

  9. Experimental Comparison of Two Configurations of Hybrid Photovoltaic Thermal Collectors

    International Nuclear Information System (INIS)

    The combination of a thermal collector and a photovoltaic module in a single system allows for increased efficiency of the total conversion of solar energy. A synergistic effect can be obtained in a structure combining these two devices in a judicious manner to those of thermal and photovoltaic system installed separately. Production of total energy from hybrid collector depends on the input (that is to say, the. energy of solar radiation, air temperature and wind speed) and output which is the electric production and the temperature of the system. Thin production also depends on the mode of heal extraction. In this paper, an experimental Study of two configurations of hybrid collectors is described. The configuration that the absorber is made by galvanized steel and in the second, the absorber is a copper serpentine. The advantages of the first configuration are mainly due to low cost and simplicity but the second configuration has the advantage of promoting the heat transfer between cells and fluid. (authors)

  10. Solar systems with highly efficient collectors

    Science.gov (United States)

    Vitt, B.

    1985-11-01

    Seasonal performance data of solar thermal systems are reported. For southern and middle European climatic conditions, systems with constant operating temperature, two types of a domestic hot water system, as well as a space heating system were evaluated. The results are related to the thermo-optical properties of the collectors. A heat pipe evacuated tubular collector was examined. The impact of the optimization of the selective absorber coating on performance was studied. It is concluded that optimized evacuated tube collectors can be used to generate heat at temperatures 200 C.

  11. Next Generation Solar Collectors for CSP

    Energy Technology Data Exchange (ETDEWEB)

    Molnar, Attila [3M Company, St. Paul, MN (United States); Charles, Ruth [3M Company, St. Paul, MN (United States)

    2014-07-31

    The intent of “Next Generation Solar Collectors for CSP” program was to develop key technology elements for collectors in Phase 1 (Budget Period 1), design these elements in Phase 2 (Budget Period 2) and to deploy and test the final collector in Phase 3 (Budget Period 3). 3M and DOE mutually agreed to terminate the program at the end of Budget Period 1, primarily due to timeline issues. However, significant advancements were achieved in developing a next generation reflective material and panel that has the potential to significantly improve the efficiency of CSP systems.

  12. Radiant Heating and Cooling Systems. Part two

    DEFF Research Database (Denmark)

    Kim, Kwan Woo; Olesen, Bjarne W.

    2015-01-01

    Control of the heating and cooling system needs to be able to maintain the indoor temperatures within the comfort range under the varying internal loads and external climates. To maintain a stable thermal environment, the control system needs to maintain the balance between the heat gain/loss of the building and the supplied energy from the system. Several studies in the literature deal with control.(1-4)

  13. 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)

    1979-01-01

    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.

  14. Evaluation of a tracking flat-plate solar collector in Brazil

    International Nuclear Information System (INIS)

    The continuing research for an alternative power source due to the perceived scarcity of fuel fossils has, in recent years, given solar energy a remarkable edge. Nevertheless, the Earth's daily and seasonal movement affects the intensity of the incident solar radiation. Devices can track the sun in order to ensure optimum positions with regard to incident solar radiation, maximizing the absorbed solar energy, and the useful energy gain. In this paper, a mathematical model is developed to estimate the solar radiation absorbed, the useful energy gain, and the efficiency of a flat-plate solar collector in Brazil. The results for a sun tracking flat-plate solar collector were compared to fixed devices. The full tracking system with rotation about two axes presented higher absorbed energy, when compared to the rotation about a single axe and to a fixed collector. Also, it was shown that the tilt angle for a fixed solar collector does not cause significant variations in the useful energy gain or in the absorbed solar radiation, for the same azimuth angle. - Highlights: • A model was developed for solar radiation based on experimental data for KT. • Useful energy gain and efficiency of a flat-plate solar collector were evaluated for a one-year period. • Several sun tracking systems were compared to fixed devices. • Tilt angle for a fixed device does not significantly affect the useful energy gain

  15. 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.

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

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Krejcirikova, Barbora; Kaczmarczyk, Jan; Duszyk, Marcin; Sakoi, Tomonori

    2013-01-01

    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 towa...

  17. Solar collector and process for its manufacture and erection. Sonnenkollekter und Verfahren zur Herstellung und Montage

    Energy Technology Data Exchange (ETDEWEB)

    Cost, K.

    1983-12-22

    The purpose of the invention is to provide an effective solar collector to obtain heat energy, as regards the amount of material, manufacturing costs, sale, erection and operation. According to the invention, this problem is solved by the collector consisting of foils, which are supplied unmachined, and by a flat basin being formed by these foils and by the side wall of the basin being formed by an earth wall, a wall of boards, a string or wire, a brick wall or other wall, and it being lined at least on the inside by the foil edge bent upwards. Several different foils above one another from the collector. Water is filled into this basin, on which a transparent foil floats, in particular a bubble foil. Details of the step by step erection of such a water basin collector are given together with notes on the material used.

  18. Potential of size reduction of flat-plate solar collectors when applying MWCNT nanofluid

    International Nuclear Information System (INIS)

    Flat-plate solar collector is the most popular type of collector for hot water system to replace gas or electric heater. Solar thermal energy source is clean and infinite to replace fossil fuel source that is declining and harmful to the environment. However, current solar technology is still expensive, low in efficiency and takes up a lot of space. One effective way to increase the efficiency is by applying high conductivity fluid as nanofluid. This paper analyzes the potential of size reduction of solar collector when MWCNT nanofluid is used as absorbing medium. The analysis is based on different mass flow rate, nanoparticles mass fraction, and presence of surfactant in the fluid. For the same output temperature, it can be observed that the collector's size can be reduced up to 37% of its original size when applying MWCNT nanofluid as the working fluid and thus can reduce the overall cost of the system.

  19. Grid Collector: Facilitating Efficient Selective Access from DataGrids

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Kesheng; Gu, Junmin; Lauret, Jerome; Poskanzer, Arthur M.; Shoshani, Arie; Sim, Alexander; Zhang, Wei-Ming

    2005-05-17

    The Grid Collector is a system that facilitates the effective analysis and spontaneous exploration of scientific data. It combines an efficient indexing technology with a Grid file management technology to speed up common analysis jobs on high-energy physics data and to enable some previously impractical analysis jobs. To analyze a set of high-energy collision events, one typically specifies the files containing the events of interest, reads all the events in the files, and filters out unwanted ones. Since most analysis jobs filter out significant number of events, a considerable amount of time is wasted by reading the unwanted events. The Grid Collector removes this inefficiency by allowing users to specify more precisely what events are of interest and to read only the selected events. This speeds up most analysis jobs. In existing analysis frameworks, the responsibility of bringing files from tertiary storages or remote sites to local disks falls on the users. This forces most of analysis jobs to be performed at centralized computer facilities where commonly used files are kept on large shared file systems. The Grid Collector automates file management tasks and eliminates the labor-intensive manual file transfers. This makes it much easier to perform analyses that require data files on tertiary storages and remote sites. It also makes more computer resources available for analysis jobs since they are no longer bound to the centralized facilities.

  20. Hybrid solar collector using nonimaging optics and photovoltaic components

    Science.gov (United States)

    Winston, Roland; Yablonovitch, Eli; Jiang, Lun; Widyolar, Bennett K.; Abdelhamid, Mahmoud; Scranton, Gregg; Cygan, David; Kozlov, Alexandr

    2015-08-01

    The project team of University of California at Merced (UC-M), Gas Technology Institute, and Dr. Eli Yablonovitch of University of California at Berkeley developed a novel hybrid concentrated solar photovoltaic thermal (PV/T) collector using nonimaging optics and world record single-junction Gallium arsenide (GaAs) PV components integrated with particle laden gas as thermal transfer and storage media, to simultaneously generate electricity and high temperature dispatchable heat. The collector transforms a parabolic trough, commonly used in CSP plants, into an integrated spectrum-splitting device. This places a spectrum-sensitive topping element on a secondary reflector that is registered to the thermal collection loop. The secondary reflector transmits higher energy photons for PV topping while diverting the remaining lower energy photons to the thermal media, achieving temperatures of around 400°C even under partial utilization of the solar spectrum. The collector uses the spectral selectivity property of Gallium arsenide (GaAs) cells to maximize the exergy output of the system, resulting in an estimated exergy efficiency of 48%. The thermal media is composed of fine particles of high melting point material in an inert gas that increases heat transfer and effectively stores excess heat in hot particles for later on-demand use.

  1. Performance studies of tubular flat plate collectors

    International Nuclear Information System (INIS)

    Computations have been performed for flat plate efficiency factor, heat removal factor, heat gained by fluid for different materials used for the tubes and fins of flat plate tubular solar collectors. 3 refs, 17 figs, 4 tabs

  2. Performance of a solar-thermal collector

    Science.gov (United States)

    Higa, W. H.

    1975-01-01

    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.

  3. Potential collector surface materials for divertors

    Energy Technology Data Exchange (ETDEWEB)

    Prebble, H.E.; Forty, C.B.A.; Butterworth, G.J. (AEA Fusion, Culham Lab., Abingdon (United Kingdom))

    1992-09-01

    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, V[sub 2]C and beryllium as unsuitable and BeO, SiC, TiC and TiB[sub 2] as exhibiting combinations of favourable and unfavourable properties. (orig.).

  4. 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 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

  5. Technical and economical assessment of integrated collector storage solar water heaters

    International Nuclear Information System (INIS)

    Solar water heating implementation has as effect greenhouse gas emission reduction. Romanian solar collector market and solar technologies implementation are not yet developed because the market is dominated by high cost equipment. Due to this, the author deduces that the use of simpler technologies, with lower technical performances, but inferior capital cost, will induce higher solar energy penetration into the market. One of the cheapest solutions for solar water heating is Integrated Collector Storage Solar Water Heaters technology. The author purpose an analytical method for technical and economical solar collector's performance assessment. Technical performances of the solar collectors will be compared for different types of ICSSWH's. Systems calculation will be done analytically. The starting point of the estimation is the heat balance on solar collector's boundary. Using heat transfer equation, energy fluxes and equipment efficiencies during collection and store time can be calculated. Technical performances for market existing solar collectors will be reminded. The paper conclusions are valuable for solar hot water design. (author)

  6. The material investigations of solar collector

    International Nuclear Information System (INIS)

    The prices of energy resources used for grain drying are increasing year by year. In order to reduce grain drying costs, in the Research Laboratory of Grain Drying and Storing of the faculty of Engineering, the Latvia University of Agriculture research into methods of energy - saving grain drying is in progress. In 2005 in the research laboratory equipment for experimental research into the materials of solar collectors was built for research purposes. The construction of the equipment allows simultaneous comparative studies of two materials. Experimental data is metered and recorded in the electronic equipment REG. Cell polycarbonate PC (bronze) (henceforth referred to as polycarbonate) with absorbers steel-tinplate and black coloured wood was researched in relation to the polyvinylchloride film (henceforth referred to as a film). The researches were made with different air velocities. For theoretical investigation of the air heating power in solar system we use mathematical model which solution we can use for estimation of different materials (absorbents) and its heat source

  7. New tool for standardized collector performance calculations

    DEFF Research Database (Denmark)

    Perers, Bengt; Kovacs, Peter; Olsson, Marcus; Persson, Martin; Pettersson, Ulrik

    2011-01-01

    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 tha...

  8. 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.

  9. Local Reasoning about a Copying Garbage Collector

    DEFF Research Database (Denmark)

    Torp-Smith, Noah; Birkedal, Lars; Reynolds, John C.

    2008-01-01

    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 vari...

  10. Optimize pulse jet dust collector performance

    Energy Technology Data Exchange (ETDEWEB)

    Klimczak, W.J.; Applewhite, G.

    1997-08-01

    If you have a pulse jet collector or are planning on installing one, you of course want to get the best performance possible. By the application of sound engineering in the operation, maintenance, and modification of existing pulse collectors, superior performance can be achieved. This article provides guidance on installing such a unit and operating it to get the most from it -- higher efficiency, lower power consumption, and a much longer filter element life.

  11. Solar collector design with respect to moisture problems

    DEFF Research Database (Denmark)

    Holck, Ole; Svendsen, Svend; Brunold, Stefan; Frei, Ueli; Köhl, Michael; Heck, Markus; Oversloot, Henk

    2003-01-01

    Humidity inside the collectors is one factor that can be minimised to keep the most favourable microclimatic condition for the internal materials of the collector. This microclimate inside the collector is an important factor in determining the service lifetime of an absorber coating. During the design of the collector, the location and size of ventilation holes, properties of the insulation materials and dimension of the solar collector box are parameters that have to be taken into account for ...

  12. Simulation Application for Optimization of Solar Collector Array

    OpenAIRE

    Igor Shesho*,; Done Tashevsk

    2014-01-01

    Solar systems offer a comparatively low output density , so increasing the output always means a corresponding increase in the size of the collector area. Thus collector arrays are occasionally constructed (i.e. with different azimuth angles and/or slopes, which be imposed by the location and structure available to mount the collector. In this paper is developed simulation application for optimization for the solar collector array position and number of collectors in regard of...

  13. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  15. Phase-change thermal energy storage: Final subcontract report

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    The research and development described in this document was conducted within the US Department of Energy's Solar Thermal Technology Program. 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{degree}C in low-temperature troughs to over 1500{degree}C in dish and central receiver systems. 12 refs., 119 figs., 4 tabs.

  16. 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)

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

    1994-02-01

    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.

  17. Collector and source sheaths of a finite ion temperature plasma

    International Nuclear Information System (INIS)

    The region between a Maxwellian plasma source and an absorbing surface is modeled with an electrostatic particle simulation and with a kinetic plasma-sheath model. In the kinetic model, Poisson's equation and Vlasov equations govern the velocity distribution of the ions and electrons. Our numerical and theoretical results for collector potential and plasma transport agree with the bounded model of Emmert et al., but differ somewhat from those using traditional Bohm sheath analysis. The plasma source injects equal fluxes of half-Maxwellian ions and electrons with specified mass and temperature ratios and is assumed to have a zero electric field. Representing the potential change within a distributed full-Maxwellian source region, the source potential drop depends primarily on temperature ratio and evolves a few Debye lengths from the source to neutralize the injected plasma. The plasma flows to an electrically floating collector where the more familiar electron-repelling collector sheath appears. Profiles of potential, density, drift velocity, temperature, kinetic energy flux, and heat flux are shown from simulation; all compare very well with theory. 24 refs., 7 figs., 1 tab

  18. Heat transfer in a low latitude flat-plate solar collector

    Directory of Open Access Journals (Sweden)

    Oko C.O.C.

    2012-01-01

    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.

  19. Performance evaluation for solar collectors in Taiwan

    International Nuclear Information System (INIS)

    In this paper, the global irradiation observed in Taiwan from 1990 to 1999 was used to estimate the optimal tilt angle for solar collectors. The observed data are resolved into diffusion and beam components, and transformed into instantaneous time frames using mathematical models. The energy gain on installing a single-axis tracked panel as compared to a traditional fixed panel is originally analyzed theoretically. In addition to the observation data, both types of radiation will be taken into account for comparison, i.e. both extraterrestrial radiation and global radiation predicted using empirical models. The results show that the yearly optimal angles for six selected stations are about 0.95 and 0.88 times their latitudes for extraterrestrial and predicted radiation, respectively. All of the observed irradiations are less than the predicted values for all times and stations, consequently resulting in a flatter tilt angle, with a few exceptions in summer. Since Taipei has the lowest clearness index, its yearly optimal angle calculated from observed data shows the greatest discrepancy when compared to its latitude. By employing a tracked panel, the yearly gains calculated from the observed data lie between 14.3% and 25.3%, which is significantly less than those from the extraterrestrial and predicted radiations

  20. An experimental study about effect of far infrared radiant ceramics on efficient methane fermentation

    International Nuclear Information System (INIS)

    Methane fermentation, well known as one of the methods for organic wastes treatment, has been used as an energy production process in order to produce a gaseous fuel. But methane fermentation has some problems to be solved about gas production rate and volatile solids reduction efficiency. Simple methods to improve these problems are needed. In this study, we focused on far infrared radiant ceramics as a stimulating substance to activate methanogenic bacteria. Firstly, through the experiment of one batch fermentation, it was confirmed that the ceramics in the fermenter caused increase of total gas production. Next, even through the experiment of continuous fermentation, same stimulating effect was confirmed. It was considered that this effect was caused not only by a function of bio-contactor of the ceramics but also by far infrared radiation from ceramics. (author)

  1. Luz Pozo Garza: Memoria radiante de una mujer solar

    Directory of Open Access Journals (Sweden)

    Blanco, Carmen

    2006-08-01

    Full Text Available The poetry of Luz Poz Garza is a Platonic flashing beauty cosmos ruled by clarity, depth and harmony symbolized in the name that gave birth to it: that of a “solar woman”, fully self-assured in her life and in her work, gathered in the “heart of light” of her poetry. Memoria solar, the title of her complete poetry work, contains the radiant memory of the solar woman, a curved by plenitude cosmos that shelters a first microcosmos (that of her youth poetry, red fruit such as orange o meat apple, and a second microcosmos (that of her maturity poetry of white or blue flower of total mystic lucidity, such as solar camellia, rose o lotus.La poesía de Luz Pozo Garza es un cosmos fulgurante de belleza platónica regida por la claridad, la profundidad y la armonía simbolizadas en el nombre que lo dio a luz, el de una “mujer solar” plenamente autoafirmada en su vida y en su obra, unidas en el “corazón de Luz” de su poesía. Memoria solar, el título de su obra poética completa contiene su memoria radiante de mujer solar, un cosmos curvo de plenitud que guarda un microcosmos primero, el de su poesía de juventud, de fruto rojo, cual naranja o manzana de la carne, y un microcosmos segundo, el de su poesía de madurez, de flor blanca o azul de la total lucidez mística, cual camelia, rosa o loto solares.

  2. Testing and thermal modeling of radiant panels systems as commissioning tool

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

    Winston, R.; Ogallagher, J. J.

    1992-05-01

    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.

  4. 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.

  5. Investigations of air solar collector efficiency

    International Nuclear Information System (INIS)

    In 2005 in the research laboratory equipment for experimental research into the materials of solar air collectors was built for research purposes. The construction of the equipment allows simultaneous comparative studies of materials and types. The experimental data are metered and recorded in the electronic equipment REG. Covered material polystyrol with absorbers steel-tinplate and black colored wood was researched in relation to others and location at different places of absorber. The ambient air worming degree at a stationary and sun following air collector with an equal coating surface and absorbers is compared. The air heating degree ?T in the solar collector is dependent on solar radiation I, air velocity v, type and place of absorbers. In the experimental equipment, with dimensions 10 x 50 x 100 cm , the air got hot to ?T = 6 °C in stationary positions with steel-thin plate and sun following position it rose to ?T = 10 °C at the velocity v = 0.55 m/s. On the supposition that the heating degree of air in the collector is linear dependent on sun radiation, expressions of this relation with different absorber materials of the sun following collector are found. (author)

  6. Modeling of a solar collectors absorber

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  7. 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.)

  8. 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)

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

    1996-12-31

    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.

  9. 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

  10. Analysis of wind flow around a parabolic collector (2) heat transfer from receiver tube

    Energy Technology Data Exchange (ETDEWEB)

    Naeeni, N.; Yaghoubi, M. [Engineering School, Shiraz University, Shiraz (Iran)

    2007-07-15

    Parabolic collectors of commercial solar thermal power plants are subject to variable convection heat transfer from the receiver tube. In the present study heat transfer from a receiver tube of the parabolic trough collector of the 250kW solar power plants in Shiraz, Iran, is studied taking into account the effects of variation of collector angel of attack, wind velocity and its distribution with respect to height from the ground. The governing equations for the two-dimensional steady state wind flow include continuity, momentum and energy equations and RNG-based k-{epsilon} model for turbulence scheme. Finite volume discretization method is used to solve the governing equations with wall function boundary condition and the SIMPLE approach is employed to iterate for the pressure correction and convergence of the velocity field. The momentum equation contains buoyancy force when the buoyancy effect is high and force convection effect is low. Computation is carried out for various wind velocities and different collector orientations with respect to wind direction. For solution of the energy equation, temperature of the receiver tube is taken as 350K and ambient temperature is assumed to be 300K. Various recirculation and temperature fields were observed around the receiver tube for different flow conditions. Effect of collector orientation on the average Nu number for the receiver tube was found negligible when the wind speed is low (Re=<4.5x10{sup 5} based on the collector aperture). But when the wind velocity is high (Re>4.5x10{sup 5}), the collector effect on the variation of Nu around the glass cover of the absorber tube is considerable. (author)

  11. 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

  12. Gas-filled, flat plate solar collectors

    OpenAIRE

    Vestlund, Johan

    2012-01-01

    This work treats the thermal and mechanical performances of gas-filled, flat plate solar collectors in order to achieve a better performance than that of air filled collectors. The gases examined are argon, krypton and xenon which all have lower thermal conductivity than air. The absorber is formed as a tray connected to the glass. The pressure of the gas inside is near to the ambient and since the gas volume will vary as the temperature changes, there are potential risks for fatigue in the m...

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

    Energy Technology Data Exchange (ETDEWEB)

    Ghaddar, N. [American Univ. of Beirut, Dept. of Mechanical Engineering, Beirut (Lebanon)]. E-mail: farah@aub.edu.lb; Ghali, K. [Beirut Arab Univ., Beirut (Lebanon)]. E-mail: amro@aub.edu.lb; Salam, M. [American Univ. of Beirut, Dept. of Mechanical Engineering, Beirut (Lebanon)

    2005-07-01

    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 stove position in the room with respect to the window and to the person, while maintaining the same level of comfort. (author)

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

    DEFF Research Database (Denmark)

    Perers, Bengt; Kovacs, Peter; Pettersson, Ulrik; Björkman, Johan; Martinsson, Carina; Eriksson, Jörgen

    2011-01-01

    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 dire...

  15. Behavior of a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne

    2015-01-01

    A mathematical model simulating the emptying behavior of a pressurized solar collector loop with solar collectors with a good emptying behavior is developed and validated with measured data. The calculated results are in good agreement with the measured results. The developed simulation model is therefore suitable to determine the behavior of a solar collector loop during stagnation. A volume ratio R, which is the ratio of the volume of the vapour in the upper pipes of the solar collector loop during stagnation and the fluid content of solar collectors, is introduced to determine the mass of the collector fluid pushed into the expansion vessel during stagnation, Min. A correlation function for the mass Min and the volume ratio R for solar collector loops is obtained. The function can be used to determine a suitable size of expansion vessels for solar collector loops.

  16. 21 CFR 874.4800 - Bone particle collector.

    Science.gov (United States)

    2010-04-01

    ...Surgical Devices § 874.4800 Bone particle collector. (a) Identification. A bone particle collector is a filtering device intended to be inserted...otologic surgery to collect bone particles for future use. (b)...

  17. Radiant-and-plasma technology for coal processing

    Directory of Open Access Journals (Sweden)

    Vladimir Messerle

    2012-12-01

    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.

  18. Aerodynamic thermal simulation system. Part 1: Radiant array (instruction manual)

    Science.gov (United States)

    Kitchar, A. F.; Steuffen, R. L.

    1973-01-01

    An aerodynamic thermal simulation system (ATSS) is presented. The construction of the system, the maintenance, set up, and operations are reported. System description of the radiant array is given along with the array subsystems modular heating unit, adjustable stanchion frame, cooling water system, and the gaseous nitrogen cooling system. The array configuration procedure outlines the set up and the start up. Maintenance procedures involve both lamp maintenance and reflector maintenance along with weather protection. Drawing codes are included. Descriptions of the 36 zone ATSS controls are also given. Each zone is an independent closed loop temperature control circuit. Procedures are presented for starting and stopping the system. The DATA-TRAK programmer and its operation, instruction manuals for the temperature controller and the power regulator and discriptions of peripheral equipment are discussed.

  19. EWSN BASED RELIABLE TRANSMISSION USING MOBILE DATA COLLECTOR NODE

    OpenAIRE

    R. A. Deshmukh; P. K. Deshmukh; Suruchi Nannaware

    2013-01-01

    The most important goal in event driven wireless sensor network is to transmit the event information to users as soon as possible. In typical WSN there are number of sensor nodes which detect the event and transmit data packet towards static sink, but the node which are one hop from the sink at this location there lot of chances of both network or congestion, this leads to reduce the energy and data loss (Packet drop).In our EWSN model we use mobile data collector that will collect the even...

  20. Energy savings in dust collector plants of bag house filter type. Phase 1 - Literature study; Energieffektivisering av anlaeggningar foer stoftrening med slangfilter. Etapp 1-Litteraturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Lars; Wikman, Karin; Berg, Magnus [AaF-Energi and Miljoe AB, Stockholm (Sweden)

    2004-01-01

    The largest energy demands in connection with the operation of bag house filters are the electric energy consumption for the fans, securing the flow of flue gas through the filter, and the electric energy consumption when producing the pressurized air (compressors or high pressure fans). Considering the significantly increased fan work when having a non-optimised cleaning of the filters, it seems justified to investigate the possibilities to minimise the unnecessary pressure drop. There is also a saving potential in the filter cleaning process, which otherwise may cost an unacceptable amount of pressurized air or other energy. The main purpose of this work is to develop methods to optimize the operation of bag house filters, which is started up with this report containing a follow-up of what has been done in Denmark and a confirmation of the technology status. In the next step, a case study where two-three plants are examined more in detail is suggested followed by a potential study to estimate the total energy saving potential in Sweden. Dust precipitation with bag house filters is basically a rather simple technique, which has existed in flue gas cleaning for about 50 years. From the literature study it can be established that there has been no revolutionary development in the field, but there are some work being done mainly to introduce new filter material but also to optimise the use of bag house filters with new computer based control systems. The largest potential of energy saving prevails if the filter from the beginning is overloaded, which usually is the case. The reason for overload may be a too large volume flow in relation to the filter area, that the dust has penetrated and blocked the filter, a defective filter cleaning process or that wrong filter material has been chosen. In Denmark a study has been made with the purpose to investigate the possibilities to optimise the energy consumption for bag house filters. For the three plants studied, an average energy saving of 50% was noted by exchange of filter material and improvement of the cleaning process. Other plants in Denmark have been rebuilt during the latest years but for these plants no reports have been found concerning how efficient the measures have been regarding energy demand for the filters. Today the suppliers of bag house filters have refined the control systems for the on-line cleaning of the filters. The systems differs in advance but are usually based on minimising the pressure drop on the flue gas side by keeping the dust layer thickness on the filter constant on the smallest possible level considering the flue gas dust emission. Very often this is combined with minimising the energy consumption of the cleaning process. Also the consumption of chemicals (for example limestone, active coal) are minimised by these control systems, which mainly in larger plants may be prior to minimising the electric energy consumption.

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

    Directory of Open Access Journals (Sweden)

    Atsushi Akisawa

    2012-04-01

    Full Text Available 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-crystalline silicon PVT collectors while electricity generation of multi crystalline silicon PVT is 1.2 times as much as that of amorphous silicon PVT. The maximum of heat gain from the PVT systems were obtained in March in summer. It was found that PVT collectors of unit area annually produced 1.1 × 103 kWh/m2 .year of heat and 55–83 kWh/m2.year of electricity, respectively. The results show that annual average solar factor of hot water supply is 0.45 for unit collector area. Economical evaluation based on energy costs in Thailand was conducted, which estimated the payback time would be 7 and 14 years for a-Si PVT and mc-Si PV, respectively.

  2. Experimental investigation and analysis on a concentrating solar collector using linear Fresnel lens

    International Nuclear Information System (INIS)

    A concentrating solar collector based on linear Fresnel lens is investigated experimentally in this paper. This solar collector is expected to acquire a higher thermal efficiency at a relatively high temperature level than the commonly used flat-plate or evacuated tube solar collectors. Experimental results show that the thermal efficiency is about 50% when the conversion temperature (water) is 90 deg. C. The test shows that the indication of lost energy is 0.578 W/m2 K, which is much smaller than that of commonly used evacuated tube solar collector without concentrating. In order to make analysis, a mathematical model for evacuated tube absorber heated by linear Fresnel lens has been built. The validation shows that the model agrees with the experimental data well. The analysis indicates that Fresnel lens collector with evacuated tube absorber has good efficiency (50%) in clear day even when the conversion temperature approaches 200 deg. C. The influence of ambient conditions and the percent of different types of energy loss, etc., are also analyzed.

  3. Simulación numérica de hornos de combustión equipados con quemadores radiantes / Simulação numérica de fornos de combustão equipados com queimadores radiantes

    Scientific Electronic Library Online (English)

    Andrés, Arrieta-Burgos; Francisco, Cadavid-Sierra; Andrés, Amell-Arrieta.

    2011-01-01

    Full Text Available As simulações de fornos de combustão equipados com queimadores radiantes habitualmente são realizadas assumindo uma combustão desenvolvida nos vasos queimadores. Este suposto minimiza o custo computacional ocasionado ao simular centenas de queimadores; entretanto, implica simular um forno onde não é [...] modelado desenvolvimento das reações de combustão e não se considera a interação da geometria dos queimadores nos perfis de fluxo e temperatura no interior da câmara de combustão. Este trabalho procura s us tentar a simpli ficação anter ior medindo o impacto ante uma metodologia que permite aproximar o funcionamento do forno, operando com centenas de queimadores e modelando a combustão. Os resultados obtidos mostram que as simulações diferem nas temperaturas de parede, potência que chega a carga e eficiência da câmara de combustão em: 1 K,0,07 MW e 0,3%. Abstract in spanish Las simulaciones de hornos de combustión equipados con quemadores radiantes habitualmente se realizan asumiendo una combustión desarrollada en las copas de los quemadores. Este supuesto minimiza el costo computacional ocasionado al simular cientos de quemadores; sin embargo, implica simular un horno [...] donde no se modela el desarrollo de las reacciones de combustión y no se considera la interacción de la geometría de los quemadores en los perfiles de flujo y temperatura en el interior de la cámara de combustión. Este trabajo procura sustentar la simplificación anterior midiendo el impacto frente a una metodología que permite aproximar el funcionamiento del horno, operando con cientos de quemadores y modelando la combustión. Los resultados obtenidos muestran que las simulaciones difieren en las temperaturas de pared, potencia que llega a la carga y eficiencia de la cámara de combustión en: 1 K, 0,07 MW y 0,3%. Abstract in english Simulations of combustion furnaces equipped with radiant burners are usually done assuming the presence of fully developed burning gases in the burners' outlet. This assumption minimizes the computational cost of simulating hundreds of burners. However, it involves simulating a furnace where the dev [...] elopment of combustion reactions is not taken into account, and the interaction of the geometry of the burners with the flow and temperature profiles inside the firebox is not considered. This work seeks to support the above simplification by comparing its impact to a methodology that gets closer to the actual operation of a furnace with hundreds of burners and makes it possible to model the combustion process. Results show that the simulations differ in wall temperatures, the power that reaches the load and the efficiency of firebox in: 1 K, 0.07 MW, and 0.3%.

  4. Advanced Hybrid Particulate Collector Project Management Plan

    Energy Technology Data Exchange (ETDEWEB)

    Miller, S.J.

    1995-11-01

    As the consumption of energy increases, its impact on ambient air quality has become a significant concern. Recent studies indicate that fine particles from coal combustion cause health problems as well as atmospheric visibility impairment. These problems are further compounded by the concentration of hazardous trace elements such as mercury, cadmium, selenium, and arsenic in fine particles. Therefore, a current need exists to develop superior, but economical, methods to control emissions of fine particles. Since most of the toxic metals present in coal will be in particulate form, a high level of fine- particle collection appears to be the best method of overall air toxics control. However, over 50% of mercury and a portion of selenium emissions are in vapor form and cannot be collected in particulate control devices. Therefore, this project will focus on developing technology not only to provide ultrahigh collection efficiency of particulate air toxic emissions, but also to capture vapor- phase trace metals such as mercury and selenium. Currently, the primary state-of-the-art technologies for particulate control are fabric filters (baghouses) and electrostatic precipitators (ESPs). However, they both have limitations that prevent them from achieving ultrahigh collection of fine particulate matter and vapor-phase trace metals. The objective of this project is to develop a highly reliable advanced hybrid particulate collector (AHPC) that can provide > 99.99 % particulate collection efficiency for all particle sizes between 0.01 and 50 14m, is applicable for use with all U.S. coals, and is cost-0443competitive with existing technologies. Phase I of the project is organized into three tasks: Task I - Project Management, Reporting, and Subcontract Consulting Task 2 - Modeling, Design, and Construction of 200-acfm AHPC Model Task 3 - Experimental Testing and Subcontract Consulting

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

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Krejcirikova, Barbora

    2013-01-01

    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.

  6. Behavior of a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne; Furbo, Simon; Perers, Bengt; Fan, Jianhua

    2015-01-01

    A mathematical model simulating the emptying behavior of a pressurized solar collector loop with solar collectors with a good emptying behavior is developed and validated with measured data. The calculated results are in good agreement with the measured results. The developed simulation model is therefore suitable to determine the behavior of a solar collector loop during stagnation. A volume ratio R, which is the ratio of the volume of the vapour in the upper pipes of the solar collector loop d...

  7. Solar Heating Systems with Evacuated Tubular Solar Collector

    DEFF Research Database (Denmark)

    Qin, Lin; Furbo, Simon

    1998-01-01

    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...

  8. A Series of Supramolecular Complexes for Solar Energy Conversion via Water Reduction to Produce Hydrogen: An Excited State Kinetic Analysis of Ru(II,Rh(III,Ru(II Photoinitiated Electron Collectors

    Directory of Open Access Journals (Sweden)

    Shamindri M. Arachchige

    2011-12-01

    Full Text Available Mixed-metal supramolecular complexes have been designed that photochemically absorb solar light, undergo photoinitiated electron collection and reduce water to produce hydrogen fuel using low energy visible light. This manuscript describes these systems with an analysis of the photophysics of a series of six supramolecular complexes, [{(TL2Ru(dpp}2RhX2](PF65 with TL = bpy, phen or Ph2phen with X = Cl or Br. The process of light conversion to a fuel requires a system to perform a number of complicated steps including the absorption of light, the generation of charge separation on a molecular level, the reduction by one and then two electrons and the interaction with the water substrate to produce hydrogen. The manuscript explores the rate of intramolecular electron transfer, rate of quenching of the supramolecules by the DMA electron donor, rate of reduction of the complex by DMA from the 3MLCT excited state, as well as overall rate of reduction of the complex via visible light excitation. Probing a series of complexes in detail exploring the variation of rates of important reactions as a function of sub-unit modification provides insight into the role of each process in the overall efficiency of water reduction to produce hydrogen. The kinetic analysis shows that the complexes display different rates of excited state reactions that vary with TL and halide. The role of the MLCT excited state is elucidated by this kinetic study which shows that the 3MLCT state and not the 3MMCT is likely that key contributor to the photoreduction of these complexes. The kinetic analysis of the excited state dynamics and reactions of the complexes are important as this class of supramolecules behaves as photoinitiated electron collectors and photocatalysts for the reduction of water to hydrogen.

  9. Super-radiant mode in InAs—monolayer-based Bragg structures

    Science.gov (United States)

    Pozina, G.; Kaliteevski, M. A.; Nikitina, E. V.; Denisov, D. V.; Polyakov, N. K.; Pirogov, E. V.; Goray, L. I.; Gubaydullin, A. R.; Ivanov, K. A.; Kaliteevskaya, N. A.; Egorov, A. Yu.; Clark, S. J.

    2015-10-01

    We report direct experimental evidence of the collective super-radiant mode in Bragg structure containing 60 InAs monolayer-based quantum wells (QWs) periodically arranged in GaAs matrix. Time-resolved photoluminescence measurements reveal an appearance of the additional super-radiant mode, originated from coherent collective interaction of QWs. This mode demonstrates a super-linear dependence of the intensity and radiative decay rate on the excitation power. The super-radiant mode is not manifested in the case if only a small number of QWs is excited.

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

    Science.gov (United States)

    Caudle, J. M.

    1978-01-01

    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.

  11. Evaluation of Various Retrofitting Concepts of Building Envelope for Offices Equipped with Large Radiant Ceiling Panels by Dynamic Simulations

    Directory of Open Access Journals (Sweden)

    Sabina Jordan

    2015-09-01

    Full Text Available In order to achieve significant savings in energy and an improved level of thermal comfort in retrofitted existing buildings, specific retrofitting concepts that combine new technologies and design need to be developed and implemented. Large radiant surfaces systems are now among the most promising future technologies to be used both in retrofitted and in new low-energy buildings. These kinds of systems have been the topic of several studies dealing with thermal comfort and energy utilization, but some specific issues concerning their possible use in various concepts for retrofitting are still poorly understood. In the present paper, some results of dynamic simulations, with the transient system simulation tool (TRNSYS model, of the retrofitted offices equipped with radiant ceiling panels are presented and thoroughly analysed. Based on a precise comparison of the results of these simulations with actual measurements in the offices, certain input data for the model were added, so that the model was consequently validated. The model was then applied to the evaluation of various concepts of building envelopes for office retrofitting. By means of dynamic simulations of indoor environment it was possible to determine the benefits and limitations of individual retrofitting concepts. Some specific parameters, which are relevant to these concepts, were also identified.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1978-10-01

    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.

  13. 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)

    Safrani

    2012-12-01

    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%.

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

    DEFF Research Database (Denmark)

    Taherian, H.; Kolaei, Alireza Rezania; Sadeghi, S.; Ganji, D. D.

    2011-01-01

    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.

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

    International Nuclear Information System (INIS)

    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.

  16. Model to predict design parameters and performance curves of vacuum glass heat pipe solar collectors

    International Nuclear Information System (INIS)

    Glass heat pipe solar collectors are becoming very popular for heating/sanitary water production. The use of a double glass system, with vacuum in between (Dewar scheme), allows to minimize heat dispersion to the environment, and to reach potentially temperature levels in competition with much more expensive parabolic trough concentrating solar collectors (stagnation temperatures in excess of 200 °C are reported). It opens their use to solar energy conversion (i.e. low-temperature ORC technology). However, in the technical literature there is not much information on the design criteria of these collectors, and of models for evaluating absorbed solar radiation and thermo-fluid-dynamics performance. Starting from the collector’s location weather data and tilt angle, a model to evaluate the absorbed solar radiation is developed. It is based on (I) calculation of the actual angle between solar radiation and the absorbing cylindrical pipe surface; and (II) calculation of the actual absorbed radiation by the heat pipe surface, also including the mutual shading between the different heat pipes, allowing the estimate of the performance in design conditions. Sensitivity to the main design variables is examined. The model includes heat transfer (radiation, forced/natural convection, phase transition) in the different sections of the heat pipe

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

    CERN Document Server

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

    2001-01-01

    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...

  18. Theoretical study on a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne; Furbo, Simon; Perers, Bengt

    2010-01-01

    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 coll...

  19. Performance of evacuated solar collectors with Compound Parabolic Concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Rabl, A.

    1978-01-01

    Compound Parabolic Concentrators (CPC) achieve the highest possible concentration for a given acceptance angle, permitting geometric concentration ratios up to about 2 in fixed solar collectors and up to about 10 in collectors with day-to-day tilt adjustments. Design, construction and test results are reported for several CPC collectors with evacuated receivers supplied by Corning Glass, by General Electric and by Owens-Illinois. Efficiencies of 45 percent at ..delta..T = 150/sup 0/K above ambient have been reached with a fixed collector. This collector accepts more than half of the diffuse radiation in addition to all of the direct beam, for at least seven hours per day.

  20. Oil in cracked collectors. Petrolul in colestoare fisurate

    Energy Technology Data Exchange (ETDEWEB)

    Parvu, G.

    1978-01-01

    The book contains 7 sections, which are subdivided into smaller subdivisions: lithology and petrography of rocks, which make up fissured collectors; a study of the cracked nature (macro- and microcracking); 3 oil in fissured collectors; a classification of fissured collectors; the characteristics of various methods for logging used in studying fissured collectors; the use of information obtained as a result of geophysical studies in wells to determine the geophysical and petrographic and petrophysical parameters of rocks; the influence of the cracking of the rocks on the parameters which are recorded by geophysical studies in wells and the problem of exploiting oil deposits in fissured collectors.

  1. Efficiencies of flat plate solar collectors at different flow rates

    DEFF Research Database (Denmark)

    Chen, Ziqian; Furbo, Simon; Perers, Bengt; Fan, Jianhua; Andersen, Elsa

    2012-01-01

    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 ...

  2. THEORETICAL STUDY ON A SOLAR COLLECTOR LOOP DURING STAGNATION

    OpenAIRE

    Chen, Ziqian; Dragsted, Janne; Furbo, Simon; Perers, Bengt

    2011-01-01

    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 c...

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  4. 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 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.

  5. 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

  6. A prototype photovoltaic/thermal system integrated with transpired collector

    Energy Technology Data Exchange (ETDEWEB)

    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

    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)

  7. 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 collector and stratified tank dynamic models.

  8. Photosynthetic utilization of radiant energy by CAM Dendrobium flowers

    International Nuclear Information System (INIS)

    14CO2 fixation was observed in orchid Dendrobium flowers; its rate decreased with the flower development. Chlorophyll (Chl) fluorescence in different developmental stages of flowers was compared to other green plant parts (leaf, inflorescence stalk, and fruit capsule). The photochemical efficiency of photosystem 2 (PS2) (Fv/Fm) of a leaf was 14-21 % higher than that of a mature flower perianth (sepal, petal, and labellum) which had a much lower total Chl content and Chl a/b ratio. A higher quantum yield of PS2 (?PS2) than in the mature flowers was observed in all green parts. Flower sepals had higher Chl content, Chl a/b ratio, and Fv/Fm values than the petal and labellum. During flower development the Chl content, Chl a/b ratio, Fv/Fm, and qN decreased while ?PS2 and qP remained constant. An exposure of developing flowers to irradiances above 50 µmol m-2 s-1 resulted in a very drastic drop of ?PS2 and qP, and a coherent increase of qN as compared to other green plant organs. A low saturation irradiance (PFD of 100 µmol m-2 s-1) and the increase in qN in the flower indicate that irradiation stress may occur since there is no further protection when the flower is exposed to irradiances above 100 µmol m-2 s-1. A low Chl/carotenoid ratio in mature flower perianth as a consequence of Chl content reduction in the course of flower development suggests a relief of irradiation stress via this mean. (author)

  9. Effect of Radiant Energy on Near-Surface Water

    OpenAIRE

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

    2009-01-01

    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, ...

  10. Evaluation of heat loss coefficients in solar flat plate collectors

    Directory of Open Access Journals (Sweden)

    Y. Rajasekhar

    2009-07-01

    Full Text Available Flat Plate Collectors (FPC is widely used for domestic hot-water, space heating/drying, for applications requiring temperatures less than 100oC. The absorber plate of the FPC transfers solar energy to liquid flowing inside the tubes. The flow takes place by thermosyphon effect or by forcing water through the tubes. However, some of the energy absorbed by the plate is lost to the atmosphere as temperature of the plate is higher than the ambient temperature. The efficiency of FPC is dependent on the temperature of the plate which in turn is dependent on the nature of flow of fluid inside the tube, the emissivity of the plate and glass cover, wind loss coefficient, inclination of the FPC with respect to horizontal. The objective of the present work was to evaluate theoretically and experimentally the heat loss coefficient from flat plate collector. An experimental system was designed and fabricated to conduct experiments at different heat flux conditions. The effect of other significant parameters was evaluated by conducting the experiment.

  11. Increasing the Efficiency of a Thermionic Engine Using a Negative Electron Affinity Collector

    CERN Document Server

    Smith, Joshua Ryan

    2014-01-01

    Most attention to improving vacuum thermionic energy conversion device (TEC) technology has been on improving electron emission with little attention to collector optimization. A model was developed to characterize the output characteristics of a TEC where the collector features negative electron affinity (NEA). According to the model, there are certain conditions for which the space charge limitation can be reduced or eliminated. The model is applied to devices comprised of materials reported in the literature, and predictions of output power and efficiency are made, targeting the sub-1000K hot-side regime. By slightly lowering the collector barrier height, an output power of around $1kW$, at $\\geq 20%$ efficiency for a reasonably sized device ($\\sim 0.1m^{2}$ emission area) can be achieved.

  12. Effects of nanometric hydrophobic layer on performances of solar photovoltaic collectors

    Directory of Open Access Journals (Sweden)

    Andrei BUTUZA

    2014-11-01

    Full Text Available The study refers to the experimental investigation of solar photovoltaic collectors' behaviour when the glazed surface is treated with a nanometric layer of hydrophobic solution. The experiment was carried out on two photovoltaic collectors, of which one was considered as reference and the other one was coated with a commercial hydrophobic solution. It was studied the evolution of the following electrical parameters: current, voltage, power, efficiency and daily energy production. The voltage was almost unaffected, but for all the others parameters, important drop were recorded. The preliminary conclusion of the study is that the use of hydrophobic solutions, for the treatment of glazed surfaces of solar collectors is not recommended. This hypothesis needs supplementary investigations and measurements in the context of reduced available information concerning the optical properties of hydrophobic solutions.

  13. Metal glass vacuum tube solar collectors are approaching lower-medium temperature heat application.

    Science.gov (United States)

    Jiang, Xinian

    2010-04-26

    Solar thermal collectors are widely used worldwide mainly for hot water preparation at a low temperature (less than 80 degrees C). Applications including many industrial processes and central air conditioning with absorption chillers, instead require lower-medium temperature heat (between 90 degrees C and 150 degrees C) to be driven when using solar thermal energy. The metal absorber glass vacuum tube collectors (MGVT) are developed for this type of applications. Current state-of-art and possible future technology development of MGVT are presented. PMID:20607893

  14. The sun-tracking control of solar collectors using high-performance step motors

    Science.gov (United States)

    Hughes, R. O.

    1977-01-01

    Sun-tracking solar energy-focusing devices involving a central receiver, thermionic conversion, or a distributed solar thermal collector system are described. The Perkins solar collector uses a fixed focal point about which an 18 m-diameter parabolic dish moves on tracks. The elevation axis also moves on a circular track. A microprocessor manipulates sun sensor information and sun ephemeris data to ensure correct placement. Stepper motors are digital devices which provide direct interface with digital electronics and a wide dynamic range, and could easily be associated with the microprocessors. Design philosophy, performance criteria, wind load analysis, and control system requirements are also discussed.

  15. Theoretical study on a solar collector loop during stagnation

    DEFF Research Database (Denmark)

    Chen, Ziqian; Dragsted, Janne

    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.

  16. Thermal Comfort in Simulated Office Environment with Four Convective and Radiant Cooling Systems

    DEFF Research Database (Denmark)

    Bolashikov, Zhecho Dimitrov; Mustakallio, Panu; Kolencíková, Sona; Kostov, Kalin; Melikov, Arsen Krikor; Kosonen, Risto

    2013-01-01

    Experiments with 24 human subjects in a simulated office with four cooling systems were performed. The systems were: chilled beam (CB), chilled beam with integrated radiant panel (CBR), chilled ceiling with overhead mixing ventilation (CCMV) and four desk partition mounted radiant cooling panels with overhead mixing ventilation (MVRC). Whole body thermal sensation (TS) and whole body TS acceptability under the four systems in a simulated office room for one hour exposure were collected. The simu...

  17. Experimental evaluation of heat transfer coefficients between radiant ceiling and room

    DEFF Research Database (Denmark)

    Causone, Francesco; Corgnati, Stefano P.; Filippi, Marco; Olesen, Bjarne W.

    2009-01-01

    The heat transfer coefficients between radiant surfaces and room are influenced by several parameters: surfaces temperature distributions, internal gains, air movements. The aim of this paper is to evaluate the heat transfer coefficients between radiant ceiling and room in typical conditions of occupancy of an office or residential building. Internal gains were therefore simulated using heated cylinders and heat losses using cooled surfaces. Evaluations were developed by means of experimental te...

  18. Evaluation of Test Method for Solar Collector Efficiency

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan

    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.

  19. Accommodating lithium into 3D current collectors with a submicron skeleton towards long-life lithium metal anodes

    Science.gov (United States)

    Yang, Chun-Peng; Yin, Ya-Xia; Zhang, Shuai-Feng; Li, Nian-Wu; Guo, Yu-Guo

    2015-08-01

    Lithium metal is one of the most attractive anode materials for electrochemical energy storage. However, the growth of Li dendrites during electrochemical deposition, which leads to a low Coulombic efficiency and safety concerns, has long hindered the application of rechargeable Li-metal batteries. Here we show that a 3D current collector with a submicron skeleton and high electroactive surface area can significantly improve the electrochemical deposition behaviour of Li. Li anode is accommodated in the 3D structure without uncontrollable Li dendrites. With the growth of Li dendrites being effectively suppressed, the Li anode in the 3D current collector can run for 600 h without short circuit and exhibits low voltage hysteresis. The exceptional electrochemical performance of the Li-metal anode in the 3D current collector highlights the importance of rational design of current collectors and reveals a new avenue for developing Li anodes with a long lifespan.

  20. Solar Air Collectors for Space Heating and Ventilation Applications—Performance and Case Studies under Romanian Climatic Conditions

    Directory of Open Access Journals (Sweden)

    Sanda Budea

    2014-06-01

    Full Text Available Solar air collectors have various applications: on the one hand, they can be used for air heating in cold seasons; on the other hand they can be used in summer to evacuate the warm and polluted air from residential, offices, industrial, and commercial buildings. The paper presents experimental results of a solar collector air, under the climatic conditions of the Southeastern Europe. The relationships between the direct solar irradiation, the resulting heat flow, the air velocity at the outlet, the air flow rate, the nominal regime of the collector and the efficiency of conversion of solar energy into thermal energy are all highlighted. Thus, it was shown that after a maximum 50 min, solar air collectors, with baffles and double air passage can reach over 50% efficiency for solar irradiation of 900–1000 W/m2. The article also presents a mathematical model and the results of a computational program that allows sizing solar collectors for the transfer of air, with the purpose of improving the natural ventilation of buildings. The article is completed with case studies, sizing the area to be covered with solar collectors, to ensure ventilation of a house with two floors or for an office building. In addition, the ACH (air change per hour coefficient was calculated and compared.

  1. Design and construction of a regenerative radiant tube burner

    International Nuclear Information System (INIS)

    The technological development of the gas industry in Colombia, aiming at efficient and safe use of the natural gas, requires the assimilation and adaptation of new generation, technologies for this purpose in this article results are presented on the design, construction and characterization of a prototype of a burner of regenerative radiant robe with a thermal power of 9,94 kW and a factor of air 1,05. This system takes advantage of the high exit temperature of the combustion smokes, after they go trough a metallic robe where they transfer the heat by radiation, to heat a ceramic channel that has the capacity to absorbing a part of the heat of the smokes and then transferring them to a current of cold air. The benefits of air heating are a saving in fuel, compared with other processes that don't incorporate the recovery of heat from the combustion gases. In this work it was possible to probe a methodology for the design of this type of burners and to reach maximum temperatures of heating of combustion air of 377,9 centigrade degrees, using a material available in the national market, whose regenerative properties should be studied in depth

  2. Flightweight radiantly and actively cooled panel: Thermal and structural performance

    Science.gov (United States)

    Shore, C. P.; Nowak, R. J.; Kelly, H. N.

    1982-01-01

    A 2- by 4-ft flightweight panel was subjected to thermal/structural tests representative of design flight conditions for a Mach 6.7 transport and to off-design conditions simulating flight maneuvers and cooling system failures. The panel utilized Rene 41 heat shields backed by a thin layer of insulation to radiate away most of the 12 Btu/ft2-sec incident heating. A solution of ethylene glycol in water circulating through tubes in an aluminum-honeycomb-sandwich panel absorbed the remainder of the incident heating (0.8 Btu/sq ft-sec). The panel successfully withstood (1) 46.7 hr of radiant heating which included 53 thermal cycles and 5000 cycles of uniaxial inplane loading of + or - 1200 lfb/in; (2) simulated 2g-maneuver heating conditions and simulated cooling system failures without excessive temperatures on the structural panel; and (3) the extensive thermal/structural tests and the aerothermal tests reported in NASA TP-1595 without significant damage to the structural panel, coolant leaks, or hot-gas ingress to the structural panel.

  3. Augmented control strategies for radiant floor heating systems

    Energy Technology Data Exchange (ETDEWEB)

    Zaheer-uddin, M.; Zhang, Z.L. [Concordia Univ., Center for Building Studies, Montreal, PQ (Canada); Cho, S.H. [Korea Inst. of Energy Research, Taejon (Korea)

    2002-07-01

    A dynamic model of radiant floor heating (RFH) system useful for control analysis is developed. The overall model consists of a boiler, distribution system, an embedded tube floor slab and building enclosure. The overall model is described by non-linear differential equations which were solved using finite numerical methods. Two control strategies for improving the temperature regulation in RFH systems are proposed. These are: a multistage on-off control and an augmented constant gain control (ACGC). Simulation results show that the multistage control maintains zone air temperature close to the setpoint better than the existing on-off control scheme does. Likewise, ACGC gives good zone temperature control compared to the classical proportional control. The ACGC is shown to be robust to changes in weather conditions and internal heat gains. The advantage of the control strategies proposed is that they eliminate the use of outdoor temperature sensors required in some existing control schemes. Being simple and robust, the proposed control schemes are good candidate controls for RFH systems. (Author)

  4. Heat transfers in porous media. Conduction, convection, radiant transfer; Transferts de chaleur dans les milieux poreux. Conduction, convection, rayonnement

    Energy Technology Data Exchange (ETDEWEB)

    Bories, S.; Mojtabi, A.; Prat, M.; Quintard, M. [Institut de Mecanique des Fluides de Toulouse, 31 (France)

    2008-10-15

    Multiple physico-chemical and transport phenomena take place in porous media. The study of these phenomena requires the knowledge of fluid storage, transfer and mechanical properties of these media. Like all polyphasic heterogenous systems, these properties depend on the morphology of the matrix and of the phenomena interacting in the different phases. This makes the heat transfers in porous media a particularly huge field of researches. This article makes a synthesis of these researches. Content: 1 - classification and characterization of porous media; 2 - modeling of transfer phenomena; 3 - heat transfer by conduction: concept of equivalent thermal conductivity (ETC), modeling of conduction heat transfer, ETC determination; 4 - heat transfer by convection: modeling of convection heat transfer, natural convection (in confined media, along surfaces or impermeable bodies immersed in a saturated porous medium), forced and mixed convection; 5 - radiant heat transfer: energy status equation, approximate solutions of the radiant transfer equation, use of the approximate solutions: case of fibrous insulating materials; 6 - conclusion. (J.S.)

  5. Mobile Information Collectors' Trajectory Data Warehouse Design

    OpenAIRE

    Wided Oueslati; Jalel Akaichi

    2010-01-01

    To analyze complex phenomena which involve moving objects, Trajectory Data Warehouse (TDW) seems to be an answer for many recent decision problems related to various professions (physicians, commercial representatives, transporters, ecologists ...) concerned with mobility. This work aims to make trajectories as a first class concept in the trajectory data conceptual model and to design a TDW, in which data resulting from mobile information collectors' trajectory are gathered...

  6. Collapse Dolines, Deflector Faults and Collector Channels

    OpenAIRE

    Šušterši?,F.

    2003-01-01

    In some Slovenian caves collector channels gather sinking underground streams and redirect them for potentially long distances parallel to certain faults. They formed due to permanent collapse of cave roofs at the points where they break through the faults, which function as a kind of screen and are termed deflector faults. The fault trends are marked by collapse within the caves, and by active collapse dolines at the surface.

  7. A hybrid air conditioner driven by a hybrid solar collector

    Science.gov (United States)

    Al-Alili, Ali

    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.

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

    DEFF Research Database (Denmark)

    Behrendt, Benjamin; Raimondo, Daniela

    2011-01-01

    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.

  9. Integral collector storage system with heat exchange apparatus

    Science.gov (United States)

    Rhodes, Richard O.

    2004-04-20

    The present invention relates to an integral solar energy collector storage systems. Generally, an integral collector storage system includes a tank system, a plurality of heat exchange tubes with at least some of the heat exchange tubes arranged within the tank system, a first glazing layer positioned over the tank system and a base plate positioned under the tank system. In one aspect of the invention, the tank system, the first glazing layer an the base plate each include protrusions and a clip is provided to hold the layers together. In another aspect of the invention, the first glazing layer and the base plate are ribbed to provide structural support. This arrangement is particularly useful when these components are formed from plastic. In yet another aspect of the invention, the tank system has a plurality of interconnected tank chambers formed from tubes. In this aspect, a supply header pipe and a fluid return header pipe are provided at a first end of the tank system. The heat exchange tubes have inlets coupled to the supply header pipe and outlets coupled to the return header pipe. With this arrangement, the heat exchange tubes may be inserted into the tank chambers from the first end of the tank system.

  10. Hybrid photovoltaic–thermal solar collectors dynamic modeling

    International Nuclear Information System (INIS)

    Highlights: ? A hybrid photovoltaic/thermal dynamic model is presented. ? The model, once calibrated, can predict the power output for any set of climate data. ? The physical electrical model includes explicitly thermal and irradiance dependences. ? The results agree with those obtained through steady-state characterization. ? The model approaches the junction cell temperature through the system energy balance. -- Abstract: A hybrid photovoltaic/thermal transient model has been developed and validated experimentally. The methodology extends the quasi-dynamic thermal model stated in the EN 12975 in order to involve the electrical performance and consider the dynamic behavior minimizing constraints when characterizing the collector. A backward moving average filtering procedure has been applied to improve the model response for variable working conditions. Concerning the electrical part, the model includes the thermal and radiation dependences in its variables. The results revealed that the characteristic parameters included in the model agree reasonably well with the experimental values obtained from the standard steady-state and IV characteristic curve measurements. After a calibration process, the model is a suitable tool to predict the thermal and electrical performance of a hybrid solar collector, for a specific weather data set.

  11. Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Stynes, J. K.; Ihas, B.

    2012-04-01

    The National Renewable Energy Laboratory (NREL) has developed an optical measurement tool for parabolic solar collectors that measures the combined errors due to absorber misalignment and reflector slope error. The combined absorber alignment and reflector slope errors are measured using a digital camera to photograph the reflected image of the absorber in the collector. Previous work using the image of the reflection of the absorber finds the reflector slope errors from the reflection of the absorber and an independent measurement of the absorber location. The accuracy of the reflector slope error measurement is thus dependent on the accuracy of the absorber location measurement. By measuring the combined reflector-absorber errors, the uncertainty in the absorber location measurement is eliminated. The related performance merit, the intercept factor, depends on the combined effects of the absorber alignment and reflector slope errors. Measuring the combined effect provides a simpler measurement and a more accurate input to the intercept factor estimate. The minimal equipment and setup required for this measurement technique make it ideal for field measurements.

  12. Particle deposition onto Janus and patchy spherical collectors.

    Science.gov (United States)

    Chatterjee, Reeshav; Mitra, Sushanta K; Bhattacharjee, Subir

    2011-07-19

    An Eulerian model (convection-diffusion-migration equation) is presented to study colloid deposition behavior on Janus and patchy spherical collectors using Happel cell geometry. The model aims to capture the effect of the collector surface charge heterogeneity on the particle deposition rate. Two separate cases of surface charge distribution are presented. In the first case, the surface heterogeneity is modeled as half the collector favoring deposition and the other half hindering it (Janus collectors). For the second case, the surface heterogeneity is modeled as alternate stripes of attractive and repulsive regions on the collector (patchy collectors). The model also considers fluid flow approaching the collector at different angles in addition to the standard gravity assisted and gravity hindered flow conditions to analyze the effect of the collector orientation on the deposition. It was observed that particles tend to deposit at the edges of the favorable stripes and the extent of this preferential accumulation varies along the tangential position of the collector due to the nonuniform nature of the collector. The predicted deposition behavior is compared to the patchwise heterogeneity model. The study brings to fore how recent developments in synthesis of chemically heterogeneous particles and beads can be used for improved particle capture in porous media and for designing filter beds with enhanced life. PMID:21675730

  13. Lightweight, low-cost solar energy collector

    Science.gov (United States)

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

    2006-01-01

    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.

  14. Inspection of radiant heating floor applying non-destructive testing techniques: GPR AND IRT / Inspección de suelos radiantes mediante técnicas no destructivas: GPR Y IRT

    Scientific Electronic Library Online (English)

    Susana, Lagüela-López; Mercedes, Solla-Carracelas; Lucía, Díaz-Vilariño; Julia, Armesto-González.

    2015-04-01

    Full Text Available La inspección de suelos radiantes requiere el uso de técnicas no destructivas, tratando de minimizar el impacto de la inspección, así como el tiempo y el coste, además de maximizar la información adquirida de cara al mejor diagnóstico posible. Con este objetivo, la aplicación de termografía infrarro [...] ja (IRT) y georradar (GPR) se propone para la inspección de suelos radiantes con cobertura de diferentes materiales, para evaluar las capacidades y la información adquirible con cada técnica. Los resultados muestran que cada técnica proporciona diferentes tipos de información: estado de las tuberías (IRT), geometría y configuración (GPR); concluyendo que la inspección óptima está formada por la combinación de ambas técnicas. Abstract in english The inspection of radiant heating floors requires the use of non-destructive techniques, trying to minimize inspection impact, time and cost, and maximize the information acquired so that the best possible diagnosis is given. With this goal, we propose the application of infrared thermography (IRT) [...] and ground penetrating radar (GPR) for the inspection of radiant heating floors with different floor coatings, in order to evaluate the capabilities and information acquirable with each technique. Specifically, two common floor coatings have been inspected: ceramic tiles and parquet flooring. Results show that each technique provides different information: condition of the pipelines (IRT), geometry and configuration (GPR), concluding that the optimal inspection is constituted by the combination of the two techniques.

  15. The knitted metal fiber burner: A new generation of surface combustion material for radiant heat and low NO{sub x} applications

    Energy Technology Data Exchange (ETDEWEB)

    Marrecau, W.L. [Bekaert Fiber Technologies, Marietta, GA (United States); Missoum, A. [Acotech, Marietta, GA (United States); Vansteenkiste, P.V. [Acotech SA, Zwevegem (Belgium)

    1998-10-01

    The demand for efficient, clean energy has encouraged wider use of natural gas and a renewed interest in surface combustion. The sintered metal fiber burner is a permeable surface medium for surface combustion of premixed gas and air. Its potential of handling radiant modes of up to 5,000 kW/ m{sup 2} (1.6 million Btu/h{center_dot}ft{sup 2}) allows for a powerful radiant flux with efficiencies up to 60% in a very compact and durable design. It has found ready acceptance in applications such as drying, curing, baking, grilling, and other processes where direct radiant heat is an immediate benefit. Now, a new generation of metal fiber burners has been developed: the knitted metal fiber burner. This new type of burner combines the excellent combustion performance of the sintered mat with the advantages of a textile. It is flexible, easy to mount, and offers total thermal expansion control. It handles a span of firing intensities from 100 kW/m{sup 2} (32,000 Btu/h{center_dot}ft{sup 2}) in radiant mode up to 5,000 kW/m{sup 2} (1.6 million Btu/h{center_dot}ft{sup 2}) in blue flame mode. This span of outputs is achieved with very low NO{sub x} (less than 20 ppm at 0% O{sub 2}) and CO (less than 30 ppm at 3,500 kW/m{sup 2} [1.2 millions Btu/h{center_dot}ft{sup 2}] combustion intensity at 0% O{sub 2}) emissions. The easy and compact burner design allows for immediate applications in fire tube boilers, steam generators, water heaters, hot air generation, and process heaters.

  16. Use of local convective and radiant cooling at warm environment: effect on thermal comfort and perceived air quality

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Duszyk, Marcin; Krejcirikova, Barbora; Sakoi, Tomonori; Kaczmarczyk, Jan

    2012-01-01

    The effect of four local cooling devices (convective, radiant and combined) on thermal comfort and perceived air quality 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 com...

  17. REVIEW OF PERFORMANCE AND ANALYSIS ISI FLAT PLATE COLLECTOR WITH MODIFIED FLAT PLATE COLLECTOR

    Directory of Open Access Journals (Sweden)

    MR.Y.Y.NANDURKAR

    2012-03-01

    Full Text Available The market of solar water heater of natural circulation type (thermo-siphon is fast growing in India. Initial cost of the solar water heater system at present is high because of store type design. It is necessary to make the product more popular by reducing the cost. This is possible by reducing area of liquid flat plate collector by increasing tube diameter and reducing riser length. Hence it is essential to make solar water heater in affordable range of the general public class. Present work is based on review of comparative performance and analysis of ISI flat plate collector with modified flat plat collector. The paper will be helpful for those who are working in the area of solar water heating system and their use in domestic areas.

  18. An Experimental and Analytical Study of a Radiative Cooling System with Unglazed Flat Plate Collectors

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham; Taherian, Hessam

    2012-01-01

    On an average about 40% of world energy is used in residential buildings and the largest energy consumption is allocated to the cooling and air-conditioning systems. So every attempt to economize energy consumption is very valuable. In this research a nocturnal radiative cooling system with flat plate solar collectors in a humid area, Babol, Iran, is assessed both experimentally and numerically. Different methods available in the literature are reviewed and by using a widely accepted model, the ...

  19. Experimental Verification and Analysis of Solar Parabolic Collector for Water Distillation

    OpenAIRE

    Mr. Mohd. Rizwan; Mr. Md. Abdul Raheem Junaidi; Mr. Mohammed Suleman; Mr. Mohd. Aamer Hussain

    2014-01-01

    The paper is concerned with an experimental study of parabolic trough collector with its sun tracking system designed and manufactured to facilitate rapid diffusion and widespread use of solar energy. The paper focuses on use of alternative source of energy (through suns radiation) which is easy to install, operate and maintain. Also, to improve the performance of solar concentrator, different geometries were evaluated with respect to their optical and energy conve...

  20. Numerical simulation of concentrating solar collector P2CC with a small concentrating ratio

    Directory of Open Access Journals (Sweden)

    Stefanovi? Velimir P.

    2012-01-01

    Full Text Available Solar energy may be practically utilized directly through transformation into heat, electrical or chemical energy. A physical and mathematical model is presented, as well as a numerical procedure for predicting thermal performances of the P2CC solar concentrator. The demonstrated prototype has the reception angle of 110° at concentration ratio CR = 1.38, with the significant reception of diffuse radiation. The solar collector P2CC is designed for the area of middle temperature conversion of solar radiation into heat. The working fluid is water with laminar flow through a copper pipe surrounded by an evacuated glass layer. Based on the physical model, a mathematical model is introduced, which consists of energy balance equations for four collector components. In this paper, water temperatures in flow directions are numerically predicted, as well as temperatures of relevant P2CC collector components for various values of input temperatures and mass flow rates of the working fluid, and also for various values of direct sunlight radiation and for different collector lengths. The device which is used to transform solar energy to heat is referred to as solar collector. This paper gives numerical estimated changes of temperature in the direction of fluid flow for different flow rates, different solar radiation intensity and different inlet fluid temperatures. The increase in fluid flow reduces output temperature, while the increase in solar radiation intensity and inlet water temperature increases output temperature of water. Furthermore, the dependence on fluid output temperature is determined, along with the current efficiency by the number of nodes in the numerical calculation.

  1. Study on solar collector utilizing electro-hydrodynamical effect; Denki ryutai rikigaku koka wo riyosuru taiyo shunetsuki no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M.; Aoki, H.; Wako, Y. [Hachinohe Institute of Technology, Aomori (Japan)

    1997-11-25

    This paper proposes a cone type electro-hydrodynamical (EHD) heat collector, describes its structure and principle, and mentions possibility of improving the heat collecting efficiency. The paper proposes a heat collector with a shape close to a cone. Trees are of cone form so that their every leaf, branch and truck can capture solar energy efficiently. Imitating this fact existing in the natural world, a cone-shaped heat collector was fabricated on a trial basis to discuss its heat collecting efficiency. Furthermore, black round stones are placed in the inner cone of the cone- shaped heat collector of double-glass structure. A low boiling point medium is placed between the inner and outer cones to cause corona discharge in vapor generated by absorbing the solar heat, and generate corona wind for an attempt to accelerate heat transfer into a heat exchanger. Thus, development was made on a cone-shaped high-efficiency heat collector utilizing electro-hydrodynamical (EHD) effect, and elucidation was given on dynamic phenomena of an electro-thermal fluid. Heat transfer in the EHD heat collector has a possibility of being accelerated by generation of ionic wind. In addition, it is thought that there would be an optimum value in applied voltage to increase electric charge supply as a result of corona discharge. 1 ref., 2 figs.

  2. SOFAS market inquiry 1998. Solar collectors and photovoltaic modules in the year 1998

    International Nuclear Information System (INIS)

    Beginning 1984, the Swiss Professional Association of Solar Energy Firms (SOFAS) collects data on solar collector and photovoltaic module sales in Switzerland. The data enter the 'Swiss statistics of renewable energy sources' in the annual report of the action programme 'Energy 2000' as well as the 'General energy statistics' of the Swiss government. In this way, the total energy output of solar heating systems (for domestic hot water preparation, space heating, swimming pool heating, and hay drying) as well as that of photovoltaic systems is available since 1993 in Switzerland. For years, the installed collector and module area is growing continuously. Especially for photovoltaics the subsidy programme of the government has a clear impact on the market tabs., figs

  3. SOME PROBLEMS OF HEAT TRANSFER IN SOLAR HEAT COLLECTORS

    Directory of Open Access Journals (Sweden)

    Wies?aw Gogó?

    1979-01-01

    Full Text Available Fundamental problems of heat transfer in most commonly used solar heat collectors have been presented. A short survey of different types of collectors and possibilities of their application have been given. For consideration of heat transfer problems two representative types of collectors have been chosen: a flat-plate collector and a parabolic focusing collector with a cylindrical absorber of circular cross section. Various forms of thermal balances have been presented and the analysis of complex heat transfer processes by radiation, convection and conduction has been carried out. The influence of heat transfer phenomena on thermal power and collectors efficiency has been studied with particular emphasis given on thermal processes joined with geometrical ontics and properties of materials in use.

  4. Survey of active solar thermal collectors, industry and markets in Canada : final report

    International Nuclear Information System (INIS)

    A survey of the solar thermal industry in Canada was presented. The aim of the survey was to determine the size of the Canadian solar thermal industry and market. Data were used to derive thermal energy output as well as avoided greenhouse gas (GHG) emissions from solar thermal systems. The questionnaire was distributed to 268 representatives. Results revealed annual sales of 24.2, 26.4 and 37.5 MWTH in 2002, 2003, and 2004 respectively, which represented over 50 per cent growth in the operating base during the 3 year survey period. Sales of all collector types grew substantially during the 3 year period, and survey respondents anticipated 20 per cent growth in both 2005 and 2006. Approximately 10 per cent of all sales were exported during 2002-2004. Unglazed liquid collectors constituted the majority of collector types sold in Canada, almost all of which were sold into the residential sector for swimming pool heating. The majority of air collectors were sold into the industrial/commercial and institutional (I/CI) sectors for use in space heating. Sales of liquid glazed and evacuated tube collectors were split between the residential and I/CI sectors. Residential sales were primarily for domestic water heating. In 2004, 23 per cent of sales in the residential sector were for combination domestic hot water and space heating applications, an indication of strong growth. Results of the survey indicated that the solar thermal market in Quebec differed from other regions, with more than double the annual per capita revenue of any other region as a result of greater market penetration of unglazed air collectors. Calculations of the GHG emissions avoided due to active solar thermal systems were made based on historical estimates of solar thermal installations. A model was developed to calculate an operating base by collector type from 1979 to the present. The model showed that many of the systems installed during the 1980s were decommissioned during the 1990s, and that the operating base of solar thermal systems in Canada only began to increase again in recent years. The estimated GHG emissions avoided from all active solar systems operating in Canada during 2004 were 23, 200 tonnes of CO2 equivalent. It was anticipated that the expected avoidance of CO2 emissions from solar collectors sold and installed in Canada during 2004 will total 122,600 tonnes over their 20-30 year life. 8 refs., 8 tabs., 12 figs

  5. La garantía de calidad del tratamiento radiante: enfoques médicos

    Directory of Open Access Journals (Sweden)

    José Alert Silva

    2002-10-01

    Full Text Available La radioterapia constituye una de las armas terapéuticas básicas en la atención de los tumores malignos: entre un 50 y 60 % son susceptibles de ser irradiados en el curso de su evolución, ya sea con intención curativa como paliativa. Los objetivos de todo tratamiento radiante son el llevar una dosis adecuada y lo más homogénea posible al volumen tumoral, preservar los tejidos sanos y una exposición mínima al personal de salud expuesto. Para poder garantizar estos objetivos es preciso aplicar un control o garantía de calidad, que comprende aspectos médicos y físicos, estrechamente imbricados. Entre los aspectos médicos se encuentran: a aquellos que comprenden los programas o políticas de tratamiento, donde se definen las técnicas propuestas, irradiación externa, braquiterapia, dosis, áreas o volúmenes o irradiar teniendo en cuenta estadios, localizaciones, etc., y donde se precisan acciones definidas según los pasos a seguir (evaluación multidisciplinaria, decisión terapéutica, planeación del tratamiento, verificación y ejecución del mismo, acciones que tienen en cuenta los pasos médicos, pero también aspectos físicos del mismo, como la dosimetría, los dispositivos de inmovilización, bloqueos, etc.; b aquellos que comprenden elementos técnicos y físicos, como controles en equipos de simulación, irradiación, etc., y la correcta aplicación diaria del tratamiento indicado y planificado y c revisiones periódicas de los programas de tratamiento, seguimiento de los casos y resultados obtenidos. De lo anterior se infiere la necesidad de tener y aplicar un programa de control de calidad del tratamiento radiante, que garantiza un tratamiento de calidad óptima.Radiotherapy is one of the basic therapeutical tools in the management of malignant tumors: 50-60% is susceptible to radiation in the course of their evolution, either for curative or palliative purposes. The objectives of radiotherapy are to apply the most homogenous adequate dose to the tumor volume, to preserve the healthy tissues and to have minimum exposure of the health care staff. To assure these objectives, it is necessary to apply a quality control or assurance that covers closely related medical and physical aspects. Among the medical aspects there are: a those comprising the therapeutical programs or policies which define the proposed techniques, the external radiation, brachytherapy, dose, areas or volumes to be irradiated, taking into account tumor staging, locations, etc. and specify certain actions according to the steps to be followed (multidisciplinary evaluation, therapeutical decision, treatment planning, implementation and verification of therapy, actions that cover not only medical steps but also physical aspects such as dosimetry, inmmobilization devices, blockage, etc; bthose comprising technical and physical elements such as check-ins in simulation equipment, radiation equipment, and the daily correct application of the prescribed and planned treatment, and csystematic reviews of treatment programs, follow-up of cases and obtained results. It may be inferred from the above-mentioned that it is required to have and apply a quality control program for radiotherapy that assures an optimum quality treatment.

  6. La garantía de calidad del tratamiento radiante: enfoques médicos

    Scientific Electronic Library Online (English)

    José, Alert Silva.

    2002-10-01

    Full Text Available La radioterapia constituye una de las armas terapéuticas básicas en la atención de los tumores malignos: entre un 50 y 60 % son susceptibles de ser irradiados en el curso de su evolución, ya sea con intención curativa como paliativa. Los objetivos de todo tratamiento radiante son el llevar una dosis [...] adecuada y lo más homogénea posible al volumen tumoral, preservar los tejidos sanos y una exposición mínima al personal de salud expuesto. Para poder garantizar estos objetivos es preciso aplicar un control o garantía de calidad, que comprende aspectos médicos y físicos, estrechamente imbricados. Entre los aspectos médicos se encuentran: a) aquellos que comprenden los programas o políticas de tratamiento, donde se definen las técnicas propuestas, irradiación externa, braquiterapia, dosis, áreas o volúmenes o irradiar teniendo en cuenta estadios, localizaciones, etc., y donde se precisan acciones definidas según los pasos a seguir (evaluación multidisciplinaria, decisión terapéutica, planeación del tratamiento, verificación y ejecución del mismo), acciones que tienen en cuenta los pasos médicos, pero también aspectos físicos del mismo, como la dosimetría, los dispositivos de inmovilización, bloqueos, etc.; b) aquellos que comprenden elementos técnicos y físicos, como controles en equipos de simulación, irradiación, etc., y la correcta aplicación diaria del tratamiento indicado y planificado y c) revisiones periódicas de los programas de tratamiento, seguimiento de los casos y resultados obtenidos. De lo anterior se infiere la necesidad de tener y aplicar un programa de control de calidad del tratamiento radiante, que garantiza un tratamiento de calidad óptima. Abstract in english Radiotherapy is one of the basic therapeutical tools in the management of malignant tumors: 50-60% is susceptible to radiation in the course of their evolution, either for curative or palliative purposes. The objectives of radiotherapy are to apply the most homogenous adequate dose to the tumor volu [...] me, to preserve the healthy tissues and to have minimum exposure of the health care staff. To assure these objectives, it is necessary to apply a quality control or assurance that covers closely related medical and physical aspects. Among the medical aspects there are: a) those comprising the therapeutical programs or policies which define the proposed techniques, the external radiation, brachytherapy, dose, areas or volumes to be irradiated, taking into account tumor staging, locations, etc. and specify certain actions according to the steps to be followed (multidisciplinary evaluation, therapeutical decision, treatment planning, implementation and verification of therapy), actions that cover not only medical steps but also physical aspects such as dosimetry, inmmobilization devices, blockage, etc; b)those comprising technical and physical elements such as check-ins in simulation equipment, radiation equipment, and the daily correct application of the prescribed and planned treatment, and c)systematic reviews of treatment programs, follow-up of cases and obtained results. It may be inferred from the above-mentioned that it is required to have and apply a quality control program for radiotherapy that assures an optimum quality treatment.

  7. General Relativistic Radiant Shock Waves in the Post-Quasistatic Approximation

    CERN Document Server

    Rueda, J A; H, Jorge A Rueda

    2006-01-01

    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 strength of the shock increases the speed of the fluid to relativistic values and for some critical ones is larger than light speed. In addition, we find that energy conditions are very sensible to the anisotropy, specially the strong one. As a special feature of the model, we find that the contribution of the matter ...

  8. A Long Term Test of Differently Designed Evacuated Tubular Collectors

    DEFF Research Database (Denmark)

    Fan, Jianhua; Dragsted, Janne; Furbo, Simon

    2008-01-01

    During three years seven differently designed evacuated tubular collectors (ETCs) utilizing solar radiation from all directions have been investigated experimentally. The evacuated tubular solar collectors investigated include one SLL all-glass ETC from Tshinghua Solar Co. Ltd, four heat pipe ETCs and one direct flow ETC from Sunda Technolgoy Co. Ltd and one all-glass ETC with heat pipe from Exoheat AB. The collectors have been investigated side-by-side in an outdoor test facility for a long per...

  9. Mathematical modelling of unglazed solar collectors under extreme operating conditions

    DEFF Research Database (Denmark)

    Bunea, M.; Perers, Bengt; Eicher, S.; Hildbrand, C.; Bony, J.; Citherlet, S.

    2015-01-01

    Combined heat pumps and solar collectors got a renewed interest on the heating system market worldwide. Connected to the heat pump evaporator, unglazed solar collectors can considerably increase their efficiency, but they also raise the coefficient of performance of the heat pump with higher average temperature levels at the evaporator. Simulation of these systems requires a collector model that can take into account operation at very low temperatures (below freezing) and under various weather c...

  10. A tool for standardized collector performance calculations including PVT

    DEFF Research Database (Denmark)

    Perers, Bengt; Kovacs, Peter; Olsson, Marcus; Persson, Martin; Pettersson, Ulrik

    2012-01-01

    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 a...

  11. The flotation of auriferous pyrite with a mixture of collectors

    OpenAIRE

    Makanza, A.T.; Vermaak, M.K.G.; Davidtz, J.C.

    2008-01-01

    Dithiocarbonates (xanthates) have been the most widely used collectors in sulphide mineral flotation. More recently, research has resulted in the use of trithiocarbonate (TTC) collectors. The present study focuses on the effect of mixtures of C12 trithiocarbonate (C12 TTC) and sodium iso-butyl xanthate (SIBX) in the flotation of auriferous pyrite and the associated gold and uranium from cyanidation tailings. Improved gold and uranium flotation responses were observed with collector mixtures t...

  12. Initial Subdivision of Genesis Early Science Polished Aluminum Collector

    Science.gov (United States)

    Allton, J. H.; Stansbery, E. K.; McNamara, K. M.; Meshik, A.; See, T. H.; Bastien, R.

    2005-01-01

    A large surface, about 245 square centimeters, of highly polished aluminum 6061 T6 alloy was attached to the science canister thermal panel for the purpose of collecting solar wind noble gases. The analysis of this collector will be part of the Genesis Early Science results. The pre-launch configuration of the collector is shown. The collector sustained some damage during the recovery impact in Utah, September 8, 2004.

  13. FLOW DISTRIBUTION IN A SOLAR COLLECTOR PANEL WITH HORIZONTAL FINS

    DEFF Research Database (Denmark)

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

    2005-01-01

    The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontal fins. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics (CFD) calculations. Further, experimental investigations of a 12.5 m² solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evalua...

  14. Biased charge collector analysis for intense ion beam measurements

    International Nuclear Information System (INIS)

    An analysis of a biased charge collector for measuring intense ion beam parameters is presented. The propagating ion beam is assumed to be current and space charge neutralized by a thermalized, background electron population. Space-charge effects inside the charge collector are included and it is shown that in addition to the ion current density, information on the electron temperature can also be obtained from the I-V characteristics of the collector. Finally, the design requirements for the construction of a biased charge collector are summarized

  15. EFFICIENCY AND LIFETIME OF SOLAR COLLECTORS FOR SOLAR HEATING PLANTS

    DEFF Research Database (Denmark)

    2009-01-01

    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 effi...

  16. Evaluating performance from spiral polyethylene tubes as solar collectors for heating swimming pools

    Energy Technology Data Exchange (ETDEWEB)

    Stefanelli, Anderson Thiago Pontes; Marchi Neto, Ismael de; Scalon, Vicente Luiz; Padilha, Alcides [UNESP, Universidade Estadual Paulista Julio de Mesquita Filho, Bauru, SP (Brazil). Dept. de Engenharia Mecanica], e-mails: scalon@feb.unesp.br, padilha@feb.unesp.br

    2010-07-01

    The solar energy is very common in the daily of citizens from different regions in world. Environmental questions and the consequent Development of renewable energy techniques were a decisive factor for expanding this market. Currently, the solar energy is present in many different devices: as direct conversion through photovoltaic panels as in solar domestic for hot water systems(SDHWS). Another common use is in the heating system for swimming pools, that could be utilized for therapeutic or comfort reasons. The main aspect that increments this use is the economy for operation of these systems. On the other hand, these systems need a high initial investment. Reducing this cost without reduction in collector efficiency using new materials and / or alternative projects is important target for new researches. Thus, this paper aims to analyze the efficiency of one of these alternative models for heating swimming pools. The conceptual device evaluated is a low cost model. It could be made from polyethylene tubes forming spiral heat exchangers. Analysis of the system is based on a dynamic model using differential equations system including solar collector and swimming pool. Experimental radiation and other environmental conditions in the region of Bauru-SP are used for analyse the dynamic behavior of the system. The simulations are based on analysis of three main parameters: number of collectors, the pump drive time and wall thickness of the collector of polyethylene. Based on these numerical tests one can conclude that this new model of solar collector for swimming pool has a better cost benefit ratio when superficial area is equal to 80% of pool area, pump operation is alternating with four minutes turned on and 28 turned off and the polyethylene wall thickness is 1.5 mm (author)

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

    DEFF Research Database (Denmark)

    Simone, Angela; Olesen, Bjarne W.

    2009-01-01

    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.

  18. A novel solar trigeneration system based on concentrating photovoltaic/thermal collectors. Part 1: Design and simulation model

    International Nuclear Information System (INIS)

    This paper analyzes the thermodynamic performance of high-temperature PhotoVoltaic/Thermal (PVT) solar collectors. The collector is based on a combination of a parabolic dish concentrating solar thermal collector and a high efficiency solar photovoltaic collector. The PVT system under investigation allows one to produce simultaneously electrical energy and high-temperature thermal energy by solar irradiation. The main aim of this study is the design and the analysis of a concentrating PVT which is able to operate at reasonable electric and thermal efficiency up to 180 °C. In fact, the PVT is designed to be integrated in a Solar Heating and Cooling system and it must drive a two-effect absorption chiller. This capability is quite new since conventional PVT collectors usually operate below 45 °C. Among the possible high-temperature PVT systems, this paper is focused on a system consisting in a dish concentrator and in a triple-junction PV layer. In particular, the prototype consists in a parabolic dish concentrator and a planar receiver. The system is equipped with a double axis tracking system. The bottom surface of the receiver is equipped with triple-junction silicon cells whereas the top surface is insulated. In order to analyze the performance of the Concentrating PVT (CPVT) collector a detailed mathematical model was implemented. This model is based on zero-dimensional energy balances on the control volumes of the system. The simulation model allows one to calculate in detail the temperatures of the main components of the system (PV layer, concentrator, fluid inlet and outlet and metallic substrate) and the main energy flows (electrical energy, useful thermal energy, radiative losses, convective losses). The input parameters of the model include all the weather conditions (temperature, insolation, wind velocity, etc.) and the geometrical/material parameters of the systems (lengths, thermal resistances, thicknesses, etc.). Results showed that both electrical and thermal efficiencies are very good in a wide range of operating conditions. The study also includes a comprehensive sensitivity analysis in which the main design variables were varied in order to evaluate the related variations of both electrical and thermal efficiencies. - Highlights: ? A new prototype of concentrating photovoltaic thermal solar collector has been designed. ? A zero-dimensional simulation model of the collector is developed. ? The collector is equipped with triple-junction cells. ? Both thermal and electrical efficiencies are very high for the majority of the operating conditions

  19. Angular Distribution of Elastically Scattered Electrons Determined and Its Effect on Collector Performance Computed

    Science.gov (United States)

    Krainsky, Isay L.; Vaden, Karl R.

    2005-01-01

    It has been demonstrated that the suppression of secondary electron emission significantly improves the performance of electron beam collectors (ref. 1). However, a complete analysis of the effects of secondary electron emission with respect to collector performance has not been possible because of the lack of quantitative data on angular distributions of secondary electrons. Secondary electrons are emitted with energies ranging from near zero to the energy of the incident primary. For our purposes, we define elastically scattered electrons as secondary electrons within 20 percent of the incident energy. Elastically scattered electrons are of great concern because their energy allows them to follow trajectories that can carry them almost anywhere within the vacuum envelope. If these secondaries leave the collector and reenter the slow wave circuit, they can produce undesired signal distortion and oscillation.This apparatus, which was built by Krainsky (ref. 2), was used at the NASA Lewis Research Center to obtain detailed measurements of the angular distributions of elastically scattered secondaries. Data were obtained for three surfaces of significant interest to collector applications: highly polished copper, copper roughened by ion sputtering, and isotropic graphite. Lewis researchers discovered that elastically scattered electrons have a complex angular distribution that is strongly dependent on the atomic number and surface morphology of the target material, as well as the energy and angle of incidence of the primary beam. At low energies, secondary emission from polished copper in the chosen energy range is primarily directed back to the source of primary electrons (backscattering). Forward scattering increases with primary energy until, at high energies, forward scattering dominates the angular distribution. Although back-scattered secondaries dominate the distributions of the textured copper surface, the yield is substantially lower. From the standpoint of secondary emission, isotropic graphite is the most attractive material because it exhibits low yield and little back scattering.

  20. Performance of industrial mist collectors over time.

    Science.gov (United States)

    Boundy, M; Leith, D; Hands, D; Gressel, M; Burroughs, G E

    2000-12-01

    Effective, economical control of metalworking fluid mists at the source is important, because exposure to these mists may cause adverse health effects. This study investigated performance changes over time for industrial collectors that removed metalworking fluid mist in the laboratory and in a transmission plant. Aerosizers were used to measure the efficiency of each stage in several multistage collectors as a function of mist droplet diameter, for up to one year of continuous operation. Metal-mesh, first-stage filters operated at low pressure drops and were effective at removing droplets larger than 3 to 5 microns in diameter. Some second-stage filters worked better than others. Both "65 percent" and "95 percent" cartridge filters failed after only a few weeks; their efficiencies decreased substantially over that time. Pocket filters and cylindrical cartridges used as second-stage filters also decreased in efficiency for submicron droplets. Whereas filters for solid particles load continuously to form a dust cake that increases efficiency, mist filters form no cake and load only to the point where collection equals drainage. As a mist filter loads, the interstitial gas velocity increases, so that efficiency decreases for small droplets that collect by diffusion. Although a third-stage 95 percent DOP filter showed important decreases in efficiency over time for submicron droplets, third-stage HEPA filters operated with efficiencies that consistently approaches 100 percent for droplets of all sizes, even after one year of operation. These results suggest that the performance of second-stage filters can be improved if they can be made to drain collected liquid more effectively. For high efficiency, mist collectors should use a HEPA filter as a final stage. PMID:11141605

  1. Towards harmonization of forest deposition collectors - case study of comparing collector designs

    Directory of Open Access Journals (Sweden)

    Zlindra D

    2011-11-01

    Full Text Available In recent years the harmonization of methods in the frame of the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests operating under the UNECE Convention on Long-range Transboundary Air Pollution (CLRTAP has been intensified. Among the C-actions of the FutMon project (LIFE07 ENV/D/000218; 2009-2010 the C1-Dep-22(SI action was established with the goal to harmonize and develop the deposition monitoring procedures and sampling methods. The sampling equipment, spatial design of sampling plots and sampling frequency throughout Europe vary considerably. Therefore a step-by-step approach was made where the harmonized sampling equipment was developed and tested first. The selected collectors were installed at one observation plot of each participating country where measurements of throughfall and bulk deposition were run in parallel with the national collectors for a period of one year. To evaluate the agreement between methods, different statistical analyses were used including Altman-Bland plots, model II regression, and repeated measures ANOVA. Preliminary results from the “Intensive forest ecosystem monitoring plot” plot Brdo in NW Slovenia show a good agreement between national and harmonized bulk (both funnel-type collectors, while comparison of throughfall measurements indicates systematic bias between harmonized (funnel-type and national (gutter-type collectors.

  2. Mobile Information Collectors' Trajectory Data Warehouse Design

    CERN Document Server

    oueslati, wided

    2010-01-01

    To analyze complex phenomena which involve moving objects, Trajectory Data Warehouse (TDW) seems to be an answer for many recent decision problems related to various professions (physicians, commercial representatives, transporters, ecologists ...) concerned with mobility. This work aims to make trajectories as a first class concept in the trajectory data conceptual model and to design a TDW, in which data resulting from mobile information collectors' trajectory are gathered. These data will be analyzed, according to trajectory characteristics, for decision making purposes, such as new products commercialization, new commerce implementation, etc.

  3. Mobile Information Collectors Trajectory Data Warehouse Design

    Directory of Open Access Journals (Sweden)

    Wided Oueslati

    2010-09-01

    Full Text Available To analyze complex phenomena which involve moving objects, Trajectory Data Warehouse (TDW seemsto be an answer for many recent decision problems related to various professions (physicians,commercial representatives, transporters, ecologists … concerned with mobility. This work aims to maketrajectories as a first class concept in the trajectory data conceptual model and to design a TDW, inwhich data resulting from mobile information collectors’ trajectory are gathered. These data will beanalyzed, according to trajectory characteristics, for decision making purposes, such as new productscommercialization, new commerce implementation, etc.

  4. Uji Coba Awal Parabolic Trough Solar Collector

    OpenAIRE

    Ghalya Pikra; Agus Salim; Andri Joko Purwanto; Zaidan Eddy

    2011-01-01

    This paper discusses initial trials of parabolic trough solar collector (PTSC) in Bandung. PTSC model consists of concentrator, absorber and tracking system. Concentrator designs are made with 2m aperture width, 6m length and 0.75m focal distance. The design is equipped with an automatic tracking system which is driven using 12V and 24Watt DC motor with 0.0125rpm rotational speed. Absorber/receiver is designed with evacuated tube type, with 1 inch core diameter and tube made of AISI304 and co...

  5. CMS DT Upgrade The Sector Collector Relocation

    CERN Document Server

    Navarro Tobar, Alvaro

    2015-01-01

    The Sector Collector relocation is the first stage of the upgrade program for the Drift Tubes subdetector of the CMS experiment. It was accomplished during Long Shutdown 2013-2014, and consisted in the relocation of the second-level trigger and readout electronics from the experimental to the service cavern, relieving the environmental constraints and improving accessibility for maintenance and upgrade. Extending the electrical links would degrade reliability, so the information is converted to optical with a custom system capable of dealing with the DC-unbalanced data. Initially, present electronics are used, so optical-to-copper conversion has also been installed.

  6. 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)

    Vandevelde, R.

    1983-01-01

    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.

  7. Fast time-resolved aerosol collector: proof of concept

    Directory of Open Access Journals (Sweden)

    X.-Y. Yu

    2010-10-01

    Full Text Available Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC" microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4–17 ms in this setup, and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.

  8. Fast time-resolved aerosol collector: proof of concept

    Directory of Open Access Journals (Sweden)

    X.-Y. Yu

    2010-06-01

    Full Text Available Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC" microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4–17 ms in this setup, and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.

  9. Energetic Performances Study of an Integrated Collector Storage Solar Water Heater

    OpenAIRE

    O. Helal; B. Chaouachi; S. Gabsi; C. Bouden

    2010-01-01

    Problem statement: Although that the interest attributed to the solar energy remains relatively limited, we attend today to the conception of several installations using the sun as energy source among which we quote the solar water heater. Approach: A study of energetic performances was taken on an integrated collector/storage solar water heater made in the National School of Engineers of Gabes. This water heater is equipped with a concentration system containing a reflector composed of three...

  10. Numerical simulation of concentrating solar collector P2CC with a small concentrating ratio

    OpenAIRE

    Stefanovi? Velimir P.; Pavlovi? Saša R.; Ili? Marko N.; Apostolovi? Nenad S.; Kuštrimovi? Dragan D.

    2012-01-01

    Solar energy may be practically utilized directly through transformation into heat, electrical or chemical energy. A physical and mathematical model is presented, as well as a numerical procedure for predicting thermal performances of the P2CC solar concentrator. The demonstrated prototype has the reception angle of 110° at concentration ratio CR = 1.38, with the significant reception of diffuse radiation. The solar collector P2CC is designed for the area of middle temperature conversio...

  11. Feasibility & design of PV-T polymer solar collector for real estate households in Addis Ababa

    OpenAIRE

    Hagos, Seyfe

    2011-01-01

    A combined application of PV and polymer thermal solar collector (PVT) of solar energy for residential electricity and thermal demand can be harnessed sustainably with effective means at a time where long sun duration and most consistent solar irradiation throughout the year is available, in place like Addis Ababa, Ethiopia.Due to frequent power shedding though out the country which Addis Ababa is part of problem, because of the energy demand in the country is increasing and a source of elect...

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

    Directory of Open Access Journals (Sweden)

    Elena Axinte

    2010-01-01

    Full Text Available 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 adopted for the interface with the building itself. The necessity of considering the maximum wind speeds actions along other dynamic effects of its turbulence is the result of a many years experience, specially if one must also think in terms of efficiency and costs both for construction and exploitation. The pattern of the wind flow field suffers intricate alterations in the proximity of these collectors placed in the vicinity of the building surface and, in these situations, it is common to test the models at a reduced scale in wind tunnels with atmospheric boundary layers. The experimental study presented in this paper was undertaken in the Laboratory of Aerodynamics of the Faculty of Construction and Building Services in Ia?i and it reveals the results and the conclusions drawn from the analysis of the wind flow over a row of collectors differently arranged in order to evaluate the wind pressure coefficients used in design.

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

    DEFF Research Database (Denmark)

    Corgnati, S. P.; Perino, M.

    2009-01-01

    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

  14. Development of a low-cost black-liquid solar collector, Phase II. Second semi-annual report, March 1, 1980-August 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Landstrom, D.K.; Talbert, S.G.; McGinniss, V.D.

    1980-09-30

    Battelle's Columbus Laboratories (BCL) is continuing its research effort to develop an efficient, low-temperature, low-cost, flat-plate black-liquid solar collector. The research efforts during this second 6-month period of Phase II have been directed toward (1) evaluating the long-term durability of various plastic materials and solar collector designs, (2) obtaining sufficient outdoor performance data to design a full-scale demonstration of a black-liquid solar collector for a commercial application, (3) working closely with a company willing to commercialize black liquid plastic collectors, and (4) incorporating improved black liquids with the identified plastic collector designs. Besides conducting indoor weathering tests of various plastic materials, two outdoor automated test facilities have been operated. One unit has been in use since February 1980 at Battelle in Columbus, Ohio, and the other unit began operation in May 1980 at Ramada Energy Systems, Inc., a collector manufacturing company near Phoenix, Arizona. Since Ramada Energy Systems has been working with extruded polycarbonate panels, Battelle has been working to date with extruded acrylic panel designs. Other potential plastics for solar collectors are being evaluated by exposure testing.

  15. Contactless two-stage line focus collectors

    Energy Technology Data Exchange (ETDEWEB)

    Benitez, P.; Minano, J.C. [Instituto de Energia Solar, ETSI Telecomunication, Madrid (Spain)

    1999-03-01

    Two new two-mirror solar collectors for tubular receiver, the Snail concentrator and the Helmet concentrator, are presented. The main feature of these concentrators is that they have a sizeable gap between the secondary mirror and the absorber, and they still achieve concentrations close to the thermodynamic limit with high collection efficiencies. This characteristic makes them unique and, on the contrary to the present two-stage designs, avoids the location of the secondary inside the evacuated tube. One of the differences between the Snail and the Helmet concentrators is that the last is symmetric (as the conventional parabolic trough) but the first is not. For an acceptance angle of {alpha} = {+-}73 deg. and a collection efficiency of 96.8% (i.e. 3.2% of the rays incident on the primary mirror within the acceptance angle are rejected), the Snail concentrator and the Helmet concentrator achieve an average flux concentration of 91.1% and 72.8% of the thermodynamic limit, respectively. Moreover, both concentrators have also high rim angles of the primary mirror: {+-}86.2 deg. (Helmet) and 98.8 deg. (Snail). This is of interest for a good mechanical stability of the collector. (authors)

  16. Electron storage ring BESSY as a radiometric source of calculable spectral radiant power between 0.5 and 1000 nm

    International Nuclear Information System (INIS)

    The spectral radiant power of the electron storage ring BESSY was measured absolutely in the infrared and visible, and its angular distribution in the infrared, visible, and soft-x-ray ranges. The results prove BESSY to be a standard of calculable spectral radiant power, at least for wavelengths from 0.5 to 1000 nm

  17. Inspection of radiant heating floor applying non-destructive testing techniques: GPR and IRT

    Directory of Open Access Journals (Sweden)

    Susana Lagüela-López

    2015-01-01

    Full Text Available La inspección de suelos radiantes requiere el uso de técnicas no destructivas, tratando de minimizar el impacto de la inspección, así como el tiempo y el coste, además de maximizar la información adquirida de cara al mejor diagnóstico posible. Con este objetivo, la aplicación de termografía infrarroja (IRT y georradar (GPR se propone para la inspección de suelos radiantes con cobertura de diferentes materiales, para evaluar las capacidades y la información adquirible con cada técnica. Los resultados muestran que cada técnica proporciona diferentes tipos de información: estado de las tuberías (IRT, geometría y configuración (GPR; concluyendo que la inspección óptima está formada por la combinación de ambas técnicas.

  18. Effects of pollen of pinus thunbergii induced by different radiant factors

    International Nuclear Information System (INIS)

    The effects of pollens and pollen tubes of Pinus thunbergii induced respectively by N+ beam, ?-ray and ultraviolet ray were measured, and the differences of the effects caused by the different radiant factors were distinguished. The results showed that there was obvious difference in the damages of the pollen germination and the pollen tube growth led by the radiant factors. The curve of dose effects from ?-ray irradiation was similarly S type, and that from ultraviolet ray treatment approximately L type. The effects from ion implantation expressed the two characteristics, the curve of the saddle type and the top inflation of pollen tube. (authors)

  19. Current collectors for rechargeable Li-Air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Veith, Gabriel M [ORNL; Dudney, Nancy J [ORNL

    2011-01-01

    Here we report the negative influence of porous nickel foam for use as current collectors in rechargeable Li-air batteries. Uncoated nickel foam promotes the decomposition of LiPF6-organic carbonate electrolytes under normal charging conditions reported for rechargeable Li-air cells. We have identified Ni free porous carbon supports as more appropriate cathode current collectors.

  20. Diagnostics of defeats of venous collectors of brain

    International Nuclear Information System (INIS)

    Comparative data of transcranial ultrasonic dopplerography (170 patients) and radionuclidous antroscintigraphy (124), received during diagnostics of defects of venous collectors of brain are analyzed. Five variants of defeats of venous collectors (cross, sigmoid, internal of jugular of jugular vein), but also unpaired sine (direct, confluent) are described. Received results permit to reveal interrelation of infringements of venous outflow and increase of intracranial pressure

  1. A solar air collector with integrated latent heat thermal storage

    Science.gov (United States)

    Charvat, Pavel; Ostry, Milan; Mauder, Tomas; Klimes, Lubomir

    2012-04-01

    Simulations of the behaviour of a solar air collector with integrated latent heat thermal storage were performed. The model of the collector was created with the use of coupling between TRNSYS 17 and MATLAB. Latent heat storage (Phase Change Material - PCM) was integrated with the solar absorber. The model of the latent heat storage absorber was created in MATLAB and the model of the solar air collector itself was created in TRNSYS with the use of TYPE 56. The model of the latent heat storage absorber allows specification of the PCM properties as well as other parameters. The simulated air collector was the front and back pass collector with the absorber in the middle of the air cavity. Two variants were considered for comparison; the light-weight absorber made of sheet metal and the heat-storage absorber with the PCM. Simulations were performed for the climatic conditions of the Czech Republic (using TMY weather data).

  2. A solar air collector with integrated latent heat thermal storage

    Directory of Open Access Journals (Sweden)

    Klimes Lubomir

    2012-04-01

    Full Text Available Simulations of the behaviour of a solar air collector with integrated latent heat thermal storage were performed. The model of the collector was created with the use of coupling between TRNSYS 17 and MATLAB. Latent heat storage (Phase Change Material - PCM was integrated with the solar absorber. The model of the latent heat storage absorber was created in MATLAB and the model of the solar air collector itself was created in TRNSYS with the use of TYPE 56. The model of the latent heat storage absorber allows specification of the PCM properties as well as other parameters. The simulated air collector was the front and back pass collector with the absorber in the middle of the air cavity. Two variants were considered for comparison; the light-weight absorber made of sheet metal and the heat-storage absorber with the PCM. Simulations were performed for the climatic conditions of the Czech Republic (using TMY weather data.

  3. Effect of microemulsified collector on froth flotation of coal

    Scientific Electronic Library Online (English)

    L., Li; X., Lu; J., Qiu; D., Liu.

    2013-11-01

    Full Text Available The performance of microemulsified diesel and conventional diesel collectors in coal flotation was compared by flotation indicators, including combustible recovery, ash content of the clean coal, and the flotation index. An efficient separation with lower dosage was obtained using the microemulsifie [...] d diesel collector. Under optimum separation conditions, the microemulsion consumption was 100 g/t less compared with diesel. The saving in diesel consumption using the microemulsion reached about 70%, disregarding the consumption of the surfactant and cosurfactant. Frothing tests showed that the frother dosage was decreased by using the microemulsion collector, because of the surfactant and cosurfactant added during preparation. The microemulsified diesel collector is superior to the conventional diesel collector in terms of diesel consumption and separation efficiency, but the selectivity requires further improvement.

  4. Cost-effective solar collectors using heat pipes

    Science.gov (United States)

    Ernst, D. M.

    Evacuated tubular solar collectors were selected as the only economical non-concentrating approach capable of efficient operation of chillers. The General Electric TC family of collectors was chosen because of their high level of performance and compatibility with heat pipe integration. Three heat pipe fluid-vessel combinations were identified and are continuing to be life tested at design and stagnation conditions for time periods exceeding 33,000 hours. Testing was carried out at the lower end of the environmental temperature range by freeze/thaw testing several types of water heat pipes. Two heat pipe collectors were tested using trimethylborate/1010 steel and copper/water heat pipes. Both collectors should improve performance as compared to the standard General Electric TC-100. A cost analysis showed that in volume production the heat pipes could be made for $1.50 each (1978 dollars) and would be cost effective for the performance achieved in collector testing.

  5. Experimental characterization of a radiant porous burner for low temperatures using natural gas; Caracterizacao experimental de um queimador poroso radiante a gas natural para baixas temperaturas

    Energy Technology Data Exchange (ETDEWEB)

    Catapan, Rafael C.; Hissanaga, Newton Junior; Pereira, Fernando M.; Oliveira Junior, Amir A.M. de [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica; Serfaty, Ricardo [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Freire, Luiz G.M. [PETROBRAS - RedeGasEnergia, RJ (Brazil)

    2004-07-01

    This article describes the experimental characterization of a radiant porous burner for temperatures between 500 deg C and 900 deg C. These low temperature radiant burners can be used in many practical applications as drying of paper and wood, plastic coating, food cooking and ambient heating. Two different configurations of silicon carbide porous ceramic foams were tested: one with a radian reflecting region (RRR) at the outlet and another without this region. Both configurations were able to sustain the reaction with equivalent ratio under 0,35. The configuration with a reflecting region was able to sustain flames with a minimum power of 60 kW/m{sup 2} and the other configuration with 100 W/m{sup 2}.The configuration with the RRR reached minimum superficial temperatures about 100 deg C lower than the other one. These results show that the reflecting region increases the heat recirculation inside the porous burner. The radiant efficiency varied from 20% to 35% for both burners. (author)

  6. Potency of Solar Energy Applications in Indonesia

    Directory of Open Access Journals (Sweden)

    Noer Abyor Handayani

    2012-07-01

    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.

  7. The impact of aging and mechanical destruction on the performance of the flat plate solar collector in Tafila city climate in Jordan

    Directory of Open Access Journals (Sweden)

    Sameh AlSaqoor

    2014-04-01

    Full Text Available This paper investigates the effect of aging and mechanical destruction on the performance of the flat plate solar collector. Two identical flat plate solar collectors (FPSC are tested simultaneously under same working conditions to compare the performance of heat energy absorbed. One solar plate is painted black color and the second one is painted light grey color. The black one represents the new collector after working for short time of period while the second one (light grey collector represents the collector after years of working. The two FPSC are used to heat water of mass flow rate 0.015 kg/s. The Maximum temperature of water was achieved using the black collector. The temperature of water output from the collectors for black and light grey absorber was 900C and 44 0C respectively with absorbing 470 W/m2 , whereas the output temperature for broken glazing black and light grey painted was achieved 650C and 340C respectively by absorbing 410 W/m2 . Average efficiency of FPSC for black and light grey absorber are found 55% and 12% respectively, while for broken glazing black and light grey absorber about 35% and 8% respectively.

  8. Solar Pilot Plant, Phase I. Preliminary design report. Volume III. Collector subsystem. CDRL item 2

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-05-01

    The Honeywell collector subsystem features a low-profile, multifaceted heliostat designed to provide high reflectivity and accurate angular and spatial positioning of the redirected solar energy under all conditions of wind load and mirror attitude within the design operational envelope. The heliostats are arranged in a circular field around a cavity receiver on a tower halfway south of the field center. A calibration array mounted on the receiver tower provides capability to measure individual heliostat beam location and energy periodically. This information and weather data from the collector field are transmitted to a computerized control subsystem that addresses the individual heliostat to correct pointing errors and determine when the mirrors need cleaning. This volume contains a detailed subsystem design description, a presentation of the design process, and the results of the SRE heliostat test program.

  9. Coaxial tubular solar collector constructed from polymeric materials: an experimental and transient simulation study

    International Nuclear Information System (INIS)

    An experimental study and a simulation model describing a coaxial tubular solar collector fabricated from polymeric materials, consisting of an inner black tube as a solar energy absorber in intimate contact with an outer transparent tube as an insulator, having the potential to provide low grade thermal energy at reasonable costs is reported. The simulation model describes the transient performance of the coaxial tubular polymeric solar collector utilizing non-linear equations solved by a difference splitting technique. The simulation model was first validated utilizing the experimental data and was then used to determine the optimal design parameters, viz. the inner, black absorber, and outer, transparent insulator, tube thicknesses. In addition, the effect of an annular air filled gap between the coaxial tubes on system performance was also studied. The results of the experimental and simulations studies are reported together with the optimal design specifications

  10. Energetic Performances Study of an Integrated Collector Storage Solar Water Heater

    Directory of Open Access Journals (Sweden)

    O. Helal

    2010-01-01

    Full Text Available Problem statement: Although that the interest attributed to the solar energy remains relatively limited, we attend today to the conception of several installations using the sun as energy source among which we quote the solar water heater. Approach: A study of energetic performances was taken on an integrated collector/storage solar water heater made in the National School of Engineers of Gabes. This water heater is equipped with a concentration system containing a reflector composed of three parabolic branches favorating a better absorption of solar radiance. Results: The comparison between this system and two other systems of solar water heater, composed of a storage ball with asymmetrical CPC and symmetrical CPC, showed important energetic performances despite the simplicity and the little cost of the collector. Conclusion: Several improvements are necessary to increase the direct flow whilst decrease the thermal losses and therefore make the system simpler to be installed on the building roof.

  11. Parabolic Trough Solar Collector Initial Trials

    Directory of Open Access Journals (Sweden)

    Ghalya Pikra

    2011-12-01

    Full Text Available This paper discusses initial trials of parabolic trough solar collector (PTSC in Bandung. PTSC model consists of concentrator, absorber and tracking system. Concentrator designs are made with 2m aperture width, 6m length and 0.75m focal distance. The design is equipped with an automatic tracking system which is driven using 12V and 24Watt DC motor with 0.0125rpm rotational speed. Absorber/receiver is designed with evacuated tube type, with 1 inch core diameter and tube made of AISI304 and coated with black oxide, the outer tube is borosilicate glass with a 70 mm diameter and 1.5 m length. Working fluid stored in single type of thermal storage tank, a single phase with 37.7 liter volume. PTSC model testing carried out for 2 hours and 10 minutes produces heat output and input of 11.5 kW and 0.64 kW respectively. 

  12. Analysis of WWER 1000 collector cracking mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Matocha, K.; Wozniak, J. [Vitkovice J.S.C., Ostrava (Switzerland)

    1997-12-31

    The presentation reviews the large experimental program, started in 1993 in Vitkovice, where the main aim was: (1) a detailed study of strain and thermal ageing, dissolved oxygen content and temperature on subcritical crack growth in 10NiMo8.5 (10GN2MFA) steel, (2) a detailed study of the effect of high temperature water and tube expansion technology on fracture behaviour of ligaments between holes for heat exchange tubes, and (3) a detailed study of the effect of drilling, tube expansion technology and heat treatment on residual stresses on the surface of holes for heat exchange tubes. The aim of all these investigations was to find a dominant damage mechanism responsible for collector cracking to be able to judge the efficiency of implemented modifications and suggested countermeasures and to answer a very important question whether proper operation conditions (mainly water chemistry) make the operation of steam generators made in Vitcovice safe throughout the planned lifetime. 10 refs.

  13. Alignment method for solar collector arrays

    Science.gov (United States)

    Driver, Jr., Richard B

    2012-10-23

    The present invention is directed to an improved method for establishing camera fixture location for aligning mirrors on a solar collector array (SCA) comprising multiple mirror modules. The method aligns the mirrors on a module by comparing the location of the receiver image in photographs with the predicted theoretical receiver image location. To accurately align an entire SCA, a common reference is used for all of the individual module images within the SCA. The improved method can use relative pixel location information in digital photographs along with alignment fixture inclinometer data to calculate relative locations of the fixture between modules. The absolute locations are determined by minimizing alignment asymmetry for the SCA. The method inherently aligns all of the mirrors in an SCA to the receiver, even with receiver position and module-to-module alignment errors.

  14. Genesis: Removing Contamination from Sample Collectors

    Science.gov (United States)

    Lauer, H. V.; McNamara, K. M.; Westphal, Andrew; Butterworth, A. L.; Burnett, D. S.; Jurewicz, A.; Woolum, D.; Allton, J. H.

    2005-01-01

    The Genesis mission returned to Earth on September 8, 2004, experiencing a non-nominal reentry. The parachutes which were supposed to slow and stabilize the capsule throughout the return failed to deploy, causing the capsule to impact the desert floor at a speed of nearly 200 MPH. Both the science canister and the major components of the SRC were returned before nightfall on September 8 to the prestaged cleanroom at UTTR , avoiding prolonged exposure or pending weather changes which might further contaminate the samples. The majority of the contaminants introduced as a result of the anomalous landing were in the form of particulates, including UTTR dust and soil, carbon-carbon heat shield material, and shattered collector dust (primarily silicon and germanium). Additional information is included in the original extended abstract.

  15. CFCC radiant burner assessment. Final report, April 1, 1992--July 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Schweizer, S.; Sullivan, J.

    1994-11-01

    The objective of this work was to identify methods of improving the performance of gas-fired radiant burners through the use of Continuous Fiber Ceramic Composites (CFCCs). Methods have been identified to improve the price and performance characteristics of the porous surface burner. Results are described.

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

    DEFF Research Database (Denmark)

    Mustakallio, Panu; Bolashikov, Zhecho Dimitrov

    2013-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    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.)

  18. Comparison of Different Formulations for Cranberry Phenolic Retention during Radiant Zone Drying

    Science.gov (United States)

    Novel dehydration methods to efficiently produce high quality small fruit powders for ingredients and nutritional supplements are in demand. Radiant zone drying (RZD) has recently received attention as a potential cost-effective alternative to freeze-drying or spray-drying. It is essential to unders...

  19. Exergetic and Thermoeconomic Analyses of Solar Air Heating Processes Using a Parabolic Trough Collector

    OpenAIRE

    Miguel Ángel Hernández-Román; Alejandro Manzano-Ramírez; Jorge Pineda-Piñón; Jorge Ortega-Moody

    2014-01-01

    This paper presents a theoretical and practical analysis of the application of the thermoeconomic method. A furnace for heating air is evaluated using the methodology. The furnace works with solar energy, received from a parabolic trough collector and with electricity supplied by an electric power utility. The methodology evaluates the process by the first and second law of thermodynamics as the first step then the cost analysis is applied for getting the thermoeconomic cost. For this study, ...

  20. The relation of collector and storage tank size in solar heating systems

    International Nuclear Information System (INIS)

    Highlights: ? A storage tank is used in many solar water heating systems for the storage of hot water. ? Using larger storage tanks decrease the efficiency and increases the cost of the system. ? The optimum tank size for the collector area is very important for economic solar heating systems. ? The optimum sizes of the collectors and the storage tank are determined. - Abstract: The most popular method to benefit from the solar energy is to use solar water heating systems since it is one of the cheapest way to benefit from the solar energy. The investment cost of a solar water heating system is very low, and the maintenance costs are nearly zero. Using the solar energy for solar water heating (SWH) technology has been greatly improved during the past century. A storage tank is used in many solar water heating systems for the conservation of heat energy or hot water for use when some need it. In addition, domestic hot water consumption is strongly variable in many buildings. It depends on the geographical situation, also on the country customs, and of course on the type of building usage. Above all, it depends on the inhabitants’ specific lifestyle. For that reason, to provide the hot water for consumption at the desirable temperature whenever inhabitants require it, there must be a good relevance between the collectors and storage tank. In this paper, the optimum sizes of the collectors and the storage tank are determined to design more economic and efficient solar water heating systems. A program has been developed and validated with the experimental study and environmental data. The environmental data were obtained through a whole year of operation for Erzurum, Turkey.

  1. Of solar collectors, wind power, and car sharing : Comparing and understanding successful cases of grassroots innovations

    OpenAIRE

    Ornetzeder, Michael; Rohracher, Harald

    2013-01-01

    Grassroots activities so far have not been sufficiently appreciated as sources of innovation. Transition processes towards more sustainable socio-technical energy, transport or production systems, however, are hardly imaginable without a broader participation of engaged citizens. This paper presents and compares three cases of successful grassroots innovations for sustainability. In particular we compare the development of wind technology in Denmark, the solar collector do-it-yourself movemen...

  2. A Study on the Improvement of Thermal Efficiency and Durability of All-Glass Solar Vacuum Collector Tubes

    International Nuclear Information System (INIS)

    Nature has been giving us energy from the beginning of the world. But human hardly use it. Solar energy is a kind of energy from the nature. This study has been carried out to study the use of solar energy as it is harnessed in the form of thermal energy. Solar energy is one of the most promising energy resources on earth and in space, because it is clean and inexhaustible. Heat for comfort in buildings can be provided from solar energy by systems that are similar in many respects to the water heater systems. To utilize the solar energy, we can not only solve the problem of energy shortage, but also can protect the environment and benefit the human beings. We must think about how to absorb the solar energy more efficiently, how to store more energy, and other problems such as additional electrical-heating system. This study deals with the collection of solar energy and its storage in all-glass solar vacuum tubes for different types of header design, flow passage and heat transfer devices. In order to elicit the most efficient combination of header design, flow passage, heat transfer hardware and operating conditions, we have studied four different types of solar collectors utilizing vacuum tubes. We selected the evacuated solar collector with metal cap and the all-glass evacuated solar collector. These collectors are more efficient than flat-plate collectors in both direct and diffuse solar radiation. The all-glass evacuated collector have been widely utilized due to their high efficiency, low heat losses, long lifetime and low costs. The evacuated solar collector in the present study uses a single vacuum solar collector either with a heat pipe (SEIDO 5) or with a 'dual pipe' flow passage (SEIDO 2). The one with heat pipe is designed such that the condensing section of heat pipe is inserted into a pipe header where the water from the storage tank is constantly circulated. Solar energy is transferred in the form of heat as it is ultimately saved in the storage tank. Similar principle is applied in the 'dual pipe' type where cold water enters the inner pipe and flows along the outer pipe raising its temperature thanks to the irradiation of solar energy. Different from these in its design and heat collection mechanism, all glass solar vacuum collector is utilized more efficiently and more conveniently in harnessing the solar energy. The 'U-pipe' type is one of those methods, which became quite popular recently with the usage of all glass solar vacuum tubes. Water is heated as it flows through the U-shaped copper pipe placed inside the vacuum tube. A rolled copper sheet tightly inserted along the inner surface of inner tube enhances heat transfer between the heated collector surface and the water contained in the U-shaped copper pipe. This study has been carried out a series of tests under the same conditions to elicit the most suitable model, which deems to enhance heat transfer and improve its durability in utilizing solar vacuum

  3. Thermal analysis and performance optimization of a solar water heater flat plate collector: Application to Tetouan (Morocco)

    International Nuclear Information System (INIS)

    The development of sustainable energy services like the supply of heating water may face a trade-off with a comfortable quality of life, especially in the winter season where suitable strategies to deliver an effective service are required. This paper investigates the heat transfer process as well as the thermal behavior of a flat plate collector evaluating different cover configurations. This investigation is performed according to a two-folded approach. Firstly, a complete model is formulated and implemented taking into account various modes of heat transfer in the collector. The goal is to investigate the impact of the number and types of covers on the top heat loss and the related thermal performance in order to support decision makers about the most cost-effective design. The proposed model can also be used to investigate the effect of the different parameters which may affect the performance of the collector. Secondly, a two objective constrained optimization model has been formulated and implemented to evaluate the optimality of different design approaches. The goal is to support decision makers in the definition of the optimal water flow and of the optimal collector flat area in order to give a good compromise between the collector efficiency and the output water temperature. The overall methodology has been tested on environmental data (temperature and irradiation) which are characteristic of Tetouan (Morocco). (author)

  4. Evaluation of heat transfer enhancement in air-heating collectors

    Energy Technology Data Exchange (ETDEWEB)

    Mattox, D. L.

    1979-06-01

    The present research effort was initiated for the purpose of increasing the thermal efficiency of air heating solar collectors through identification and development of optimum design and operation criteria for solar absorber-to-air heat exchangers. Initially this effort took the form of a solar collector systems analysis to evaluate the impact of various techniques for enhancing the heat transfer between the absorber and air stream on overall thermal performance of the entire solar collector. This systems analysis resulted in the selection of solar collector designs providing ducted cooling air on the absorber shaded side as a base line. A transient heat transfer analysis of a complete solar air heating collector was used to demonstrate that an optimum absorber-to-air heat exchanger design could be provided with several interrupted fin configurations. Additional analyses were performed to establish that the maximum solar collector thermal performance to required pumping power was realized for a Reynolds number range of 1000 to 2000. This Reynolds number range was used to establish a theoretical design limit curve for maximum thermal performance versus required pumping power for all interrupted fin designs as published in the open literature. Heat and momentum transfer empirical relationships were defined for scaling the state-of-the-art high conductance fin designs identified from a compact configuration to the less compact designs needed for solar collectors.

  5. An Experimental and Analytical Study of a Radiative Cooling System with Unglazed Flat Plate Collectors

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham; Taherian, Hessam

    2012-01-01

    On an average about 40% of world energy is used in residential buildings and the largest energy consumption is allocated to the cooling and air-conditioning systems. So every attempt to economize energy consumption is very valuable. In this research a nocturnal radiative cooling system with flat plate solar collectors in a humid area, Babol, Iran, is assessed both experimentally and numerically. Different methods available in the literature are reviewed and by using a widely accepted model, the sky temperature is determined. The mathematical model for a flat plate solar collector is used as a guideline to derive the governing equations of a night sky radiator. Then, a cooling loop, including a storage tank, pump, connecting pipes, and a radiator has been studied experimentally. The water is circulated through the unglazed flat-plate radiator having 4 m2 of collector area at night to be cooled by convection and radiation to sky. The experiments were carried out at various mass flow rates and in different weather conditions and the results have been compared to those of the theoretical model. The results indicate that water temperature decreases 7–8?C and the average net cooling will be ranged from 23 to 52W/m2, as the mass flow rate increases from 0.01 to 0.05 kg/s.

  6. Nanofluid optical property characterization: towards efficient direct absorption solar collectors

    Directory of Open Access Journals (Sweden)

    Otanicar Todd

    2011-01-01

    Full Text Available 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 absorption of the solar spectrum must be established. Accordingly, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (0.25 to 2.5 ?m. A simple addition of the base fluid and nanoparticle extinction coefficients is applied as an approximation of the effective nanofluid extinction coefficient. Comparisons with measured extinction coefficients reveal that the approximation works well with water-based nanofluids containing graphite nanoparticles but less well with metallic nanoparticles and/or oil-based fluids. For the materials used in this study, over 95% of incoming sunlight can be absorbed (in a nanofluid thickness ?10 cm with extremely low nanoparticle volume fractions - less than 1 × 10-5, or 10 parts per million. Thus, nanofluids could be used to absorb sunlight with a negligible amount of viscosity and/or density (read: pumping power increase.

  7. A Process Heat Application Using Parabolic Trough Collector

    Science.gov (United States)

    Y?lmaz, ?brahim Halil; Söylemez, Mehmet Sait; Hayta, Hakan; Yumruta?, Recep

    A pilot study has been performed based on a heat process application that is designed, installed and tested at Gaziantep University to establish the technical and economic feasibility of high temperature solar-assisted cooking process. The system has been designed to be satisfying the process conditions integrated with parabolic trough solar collector (PTSC). It is primarily consists of the PTSC array, auxiliary heater, plate type heat exchanger, cooking system and water heating tanks. In the operation of the process heat application, the energy required to cook wheat (used as cooking material) has been supplied from solar energy which is transferred to heat transfer fluid (HTF) by heat exchanging units and finally discharged to water in order to produce bulgur. The performance parameters of the sub-systems and the process compatibility have been accomplished depending on the system operation. In addition that the system performance of the high temperature solar heat process has been presented and the recommendations on its improvement have been evaluated by performing an experimental study. As a result that the use of solar energy in process heat application has been projected and its contribution to economics view with respect to conventional cooking systems has been conducted.

  8. The UPM high temperature solar collector current status

    International Nuclear Information System (INIS)

    The high temperature solar energy research at Universiti Putra Malaysia (UPM) is an attempt to study the merits of the fixed aperture optics collector for the equatorial region using the concept of the fixed mirror distributed focus (FMDF). The general objective is to look for an alternative source of clean energy and a practical method of converting this energy to usable form for the projected industrialisation program of the country. The FMDF uses a stationary hemisphere bowl to capture the solar irradiance. The UPM bowl has a rim angle of 120 0 with radius of curvature of 27.9 m. This corresponds to an aperture diameter of 48 m and submerges 5.1 m in the ground. The bowl will later be tiled with 2446 square meters of mirror to form a spherical shape. And therefore will be able to collect about 1 MW of solar irradiance at the conical focus formed along the direction of the radius (high concentrated region) which then can be harnessed by different means. In this paper, we will report the current status and future works of the project, under construction at the site. We anticipate that the project will be completed and operated by the year 2000. (Author)

  9. An improved dynamic test method for solar collectors

    DEFF Research Database (Denmark)

    Kong, Weiqiang; Wang, Zhifeng; Fan, Jianhua; Bacher, Peder; Perers, Bengt; Chen, Ziqian; Furbo, Simon

    2012-01-01

    A comprehensive improvement of the mathematical model for the so called transfer function method is presented in this study. This improved transfer function method can estimate the traditional solar collector parameters such as zero loss coefficient and heat loss coefficient. Two new collector parameters t and mfCf are obtained. t is a time scale parameter which can indicate the heat transfer ability of the solar collector. mfCf can be used to calculate the fluid volume content in the solar coll...

  10. Exergy analysis of a flat plate solar collector

    Scientific Electronic Library Online (English)

    Sunil, Chamoli.

    Full Text Available In this study, exergetic performance analysis of flat plate solar collector has been carried out analytically. A comprehensive mathematical modelling of thermal performance is simulated using MATLAB simulink and optimal geometrical and thermody-namic parameters are predicted pertaining to optimum pe [...] rformance of the system. The optimization procedure was applied to a typical collector and the optimum design points were extracted. The optimum values of collector inlet temperature, mass flow rate, absorber plate area, and fluid outlet temperature for maximum exergy inflow from the system have been obtained.

  11. Hydrologic engineering considerations for Ranney Collector Well Intake Systems

    International Nuclear Information System (INIS)

    The basic hydrologic aspects affecting the location, design, and operation of Ranney Collector Well intake structures are presented. Siting and design considerations are discussed and the types of problems that require site-specific design considerations are outlined. The fundamental concepts of hydrology related to collector well design, such as surface water flow regime and the more complex groundwater hydraulics, are briefly discussed. Emphasis is placed on the application of the results of field pumping tests to the estimation of aquifer properties, groundwater flow, and infiltration rates and the utilization of these parameters as input to Ranney Collector Well system design

  12. An improved dynamic test method for solar collectors

    DEFF Research Database (Denmark)

    Kong, Weiqiang; Wang, Zhifeng

    2012-01-01

    A comprehensive improvement of the mathematical model for the so called transfer function method is presented in this study. This improved transfer function method can estimate the traditional solar collector parameters such as zero loss coefficient and heat loss coefficient. Two new collector parameters t and mfCf are obtained. t is a time scale parameter which can indicate the heat transfer ability of the solar collector. mfCf can be used to calculate the fluid volume content in the solar collector or to validate the regression process by comparing it to the physical fluid volume content if known. Experiments were carried out under dynamic test conditions and then test data were processed using multi-linear regression method to get collector parameters with statistic analysis. A comparison of the collector parameters obtained from the improved transfer function (ITF) method and the quasi-dynamic test (QDT) method is carried out. The results show that the improved transfer function method can accurately obtain reasonable collector parameters. The influence of different averaging time intervals is investigated. Based on the investigation it is recommended to use on line calculation if applicable for the second-order differential term with 6–9min as the best averaging time interval. The measured and predicted collector power output of the solar collector are compared during a test of 13days continuously both for the ITF method and the QDT method. The maximum and averaging error is 53.87W/m2 and 5.22W/m2 respectively of the ITF method while 64.13W/m2 and 6.22W/m2 of the QDT method. Scatter and relative error distribution of the measured power output versus the predicted power output is also plotted for the two methods. No matter in either error analysis or scatter distribution, the ITF method is more accurate than the QDT method in predicting the power output of a solar collector.In conclusion, all the results show that the improved transfer function method can accurately and robustly estimate solar collector parameters and predict solar collector thermal performance under dynamic test conditions.

  13. Fuzzy Approximate Model for Distributed Thermal Solar Collectors Control

    KAUST Repository

    Elmetennani, Shahrazed

    2014-07-01

    This paper deals with the problem of controlling concentrated solar collectors where the objective consists of making the outlet temperature of the collector tracking a desired reference. The performance of the novel approximate model based on fuzzy theory, which has been introduced by the authors in [1], is evaluated comparing to other methods in the literature. The proposed approximation is a low order state representation derived from the physical distributed model. It reproduces the temperature transfer dynamics through the collectors accurately and allows the simplification of the control design. Simulation results show interesting performance of the proposed controller.

  14. A solar air collector with integrated latent heat thermal storage

    OpenAIRE

    Klimes Lubomir; Mauder Tomas; Ostry Milan; Charvat Pavel

    2012-01-01

    Simulations of the behaviour of a solar air collector with integrated latent heat thermal storage were performed. The model of the collector was created with the use of coupling between TRNSYS 17 and MATLAB. Latent heat storage (Phase Change Material - PCM) was integrated with the solar absorber. The model of the latent heat storage absorber was created in MATLAB and the model of the solar air collector itself was created in TRNSYS with the use of TYPE 56. The model of the latent heat storage...

  15. Thermal efficiency of low cost solar collectors - CSBC; Eficiencia termica de coletores solares de baixo custo - CSBC

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Renato C.; Shiota, Robson T.; Mello, Samuel F.; Assis Junior, Valdir; Bartoli, Julio R. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Quimica. Dept. de Tecnologia de Polimeros

    2006-07-01

    The thermal performance of a low cost flat panel solar collector was measured. This Low Cost Solar Collector is a novel concept for water heating using only thermoplastics materials, used on building: ceiling and tubes made of unplasticized PVC, but without transparent cover. The top side of the UPVC panel was black painted to be the solar radiation absorber surface. Prototypes were installed on two charity houses around Campinas and at the FEQ campus, being used without any trouble for one year. The thermal efficiency analysis followed ABNT NBR 10184 standard at the Green-Solar Laboratory, Brazilian Centre for Development of Solar Thermal Energy, PUC-Minas. It was measured a thermal efficiency of 67%, compared to the 75% usually found on conventional solar collectors made of copper tubes and with glass cover. (author)

  16. A Study on the Development of Nonglass Solar Vacuum Tube Collector

    International Nuclear Information System (INIS)

    Nature has been providing us energy from the beginning of the world. However human has hardly used it wisely. Solar energy is a kind of renewable energy from the nature. This study has been carried out to study the use of solar energy as it is harnessed in the form of thermal energy. Solar energy is one of the most promising energy resources such as hydrogen, biomass, wind and geothermal energy, because it is clean and inexhaustible. Space heating in buildings can be provided from solar energy by systems that are similar in many respects to water heater systems. By tapping into solar energy, we can not only solve the problem of energy shortage, but also can protect the environment and benefit the human beings. There are currently two types of evacuated tube; a single glass tube and a double glass tube. The former consists of a single glass tube which contains a flat or curved aluminium plate attached to a copper heat pipe or water flow pipe. The latter consists of rows of parallel transparent glass tubes, each of which contains an absorber tube. Evacuated tube collectors introduced above, however, pose some problems as they break rather easily under mechanical stresses. This paper introduces some preliminary results in design and fabrication of a non-glass solar vacuum tube collector in which the thermosyphon(heat pipe)made of copper is used as a heat transfer device. A series of tests have been performed to assess the ability of a non-glass solar vacuum tube collector. The series of experiments are as follows: 1)Vacuum level inside a vacuum tube. 2)Effects of the air remaining inside a vacuum tube on the temperature on the absorber plate. 3)Comparison of a non-glass vacuum solar collector with a single glass evacuated tube(SEIDO 5). Different vacuum levels inside non-glass vacuum tubes were applied to check any leakage or unexpected physical or chemical developments with time. The vacuum level changed from 10-2torr to 5torr in 5 days due to air infiltration from the ambient and gas emissions from the materials they were made of. The effect of vacuum levels inside a vacuum tube on the absorber plate were investigated in different conditions. Due to less heat losses to the ambient, the non-glass vacuum tube at vacuum level 10-2 torr kept more heat at higher temperatures compared to the non-glass vacuum tube collectors whose vacuum levels were at 5 torr. However, the temperature was not linearly proportional to the vacuum level. Two types of solar collectors were used to investigate the ability of non-glass solar vacuum tube: one single glass evacuated tube and one non-glass vacuum tubes(10-2torr). The efficiency of a non-glass vacuum tube with 10-2torr was different from that of a single glass evacuated tube in which vacuum level is 10-4?10-5torr due to the transmittance of ZnO. Unlike glass evacuated tubes, non-glass solar vacuum tubes generally require some measures to prevent air infiltration through invisible pores of the tube wall and gas emission from the materials. If the problems related with vacuum inside a tube are solved, the non-glass vacuum collector will work more efficiently

  17. Experimental Verification and Analysis of Solar Parabolic Collector for Water Distillation

    Directory of Open Access Journals (Sweden)

    Mr. Mohd. Rizwan

    2014-01-01

    Full Text Available The paper is concerned with an experimental study of parabolic trough collector with its sun tracking system designed and manufactured to facilitate rapid diffusion and widespread use of solar energy. The paper focuses on use of alternative source of energy (through suns radiation which is easy to install, operate and maintain. Also, to improve the performance of solar concentrator, different geometries were evaluated with respect to their optical and energy conversion efficiency. To assure good performance and long technical lifetime of a concentrating system, the solar reflectance of the reflectors must be high and long term stable. During the research carried out, focus had been shifted from evaluation of the performance of concentrating solar collector to analysis of the optical properties of reflector and absorbing materials. The shift of focus was motivated by the need to assess long term system performance and possibilities of optimizing the optical efficiency or reducing costs by using new types of reflector materials and absorbing materials. The Solar Parabolic Trough Collector (SPTC was fabricated in local workshops and the sun tracking system was assembled using electric and electronic components in the market, while the mechanical components making up the driving system were procured from the local market. The objective of the research is to obtain distilled water by heating it to a higher temperature by solar parabolic trough collector. Solar distillation is used to produce potable water or to produce water for lead acid batteries or in chemical laboratories as in this case. The level of dissolved solids in solar distilled water is less than 3 ppm and bacteria free. The requirements for this specific design are a target for distilling water regularly with low maintenance.

  18. Photovoltaic/thermal solar collectors and their potential in Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Bosanac, M.; Katic, I.; Badran, J. [Danish Technological Inst., Solar EnergyCentre (Denmark); Soerensen, B. [Novator Advanced Technology Consulting, Gilleleje (Denmark); Soerensen, H. [Esbensen Consulting Engineers Ltd., Copenhagen (Denmark)

    2001-06-01

    Within the project, the most promising design of PV/T components have been identified: 1) A water-heating collector with the PV cells acting as absorber in a direct thermal contact with water piping and 2) An air-heating hybrid PV/T wall where warm air produced by cooling of PV panels are utilised for space and water heating. For the above PV/T components, detailed mathematical models have been set and the detailed computer programs have been developed. The mathematical models have been verified by experimental results both for water-heating and air-heating components. After the theoretical-model verificaton, a multi-parametric analysis has been carried out in order to identify optimal design of the PV/T components. The effect of the influencing parameters on system performance (i.e. efficiency curve) for two basic types of collectors (selective and non-selective absorber) has been analysed. The analysis of energy yields shows that maximum energy yield can be obtained under the following conditions: The absorber absorptance should be as high as possible. The coefficient of emittance of 0.1 produces the best performance for fluid inlet temperatures 30, 50 and 70 deg. C. However, for inlet fluid temperature of 10 deg. C, the best results are achieved with coefficient of emittance of 0.95. A multi-parameter analysis has been carried out using two reference constructions of the PV/T-Wall. The first reference assumes a small light transparency for the solar spectrum and the second reference assumes a light transparency of 80%. Our first strategy was to determine the airflow rate, which leads to maximum annual yield. For the first reference, this rate was found to be 50 m{sup 3}/h/m{sup 2} and for the second it was found to be 40 m{sup 3}/h/m{sup 2}. After determination of optimum airflow rates for both systems, another study was performed in order to determine the combination design of parameters, which will lead to best energy yields. Investigation showed that the light transparency of PV wall and the incident angle modifier are most critical parameters of the system (au)

  19. Solar collector loop with large expansion vessel and evaporation in collector at high temperatures for securing solar collector fluid and plant; Solfangerkreds med stor ekspansionsbeholder og fordampning i solfanger ved faretruende hoeje temperaturer til sikring af solfangervaeske og anlaeg

    Energy Technology Data Exchange (ETDEWEB)

    Dragsted, J.; Furbo, S.; Perers, B.; Ziqian Chen

    2010-05-15

    Experimental and theoretical investigations of a solar collector loop have been carried out with Batec Solvarme's BA30 solar collector with a large expansions vessel, propylene glycol/water mixture without additives as solar collector fluid and with a circulation pump which stops at high temperatures. Pressure and temperature conditions are determined during sunny periods and stagnation in the solar collector. The investigated solar collector loop secures the solar heating system and solar collector fluid from dangerously high temperatures. In connection with the investigations an excel sheet has been constructed for determining the volume of the expansion vessel based on information of the design of the solar collector loop and the maximum allowable temperature of the solar collector fluid. (author)

  20. CFD study on a local radiant heating system and the resulting indoor climate

    Energy Technology Data Exchange (ETDEWEB)

    Limpens-Neilen, D.; Schoffelen, M.; Schellen, H. [Eindhoven Univ. of Technology, Eindhoven, (Netherlands)

    2005-07-01

    Energy costs for heating large rooms are generally high, particularly in situations where only a small zone of heating is needed within a large space or building. This paper discussed the application of a radiant bench heating system in the church of Rocca Pietore in Italy. Previously, air in the church was heated rapidly using a hot air heating system, which introduced abrupt variations in temperature and in the relative humidity of the indoor air. The variations caused damage to the building and interior furnishings such as wooden sculptures and paintings. To address these problems, a local bench heating system was designed. A Computational Fluid Dynamics (CFD) model of the bench heating, as well as the verification of the CFD results with help of measurements were presented. The influence of the local heating systems on the entire church and in the bench-heated areas was demonstrated. Three heating elements were combined into the bench heating system. The prototypes of the heating elements consisted of 2 types of electrical heat sources: heating foil and heating resistance cables. The heating element applied under the seat of the pews was a semi-circular element with a load of 155 W . A heating element was also applied beneath the kneeler pads, as well as at the back of each pew. Non-stationary time and place dependent air flows in the church made it difficult to study the effect of the heating system in real circumstances. A stationary controlled environment was used in order to investigate how the system should be modeled in CFD and to perform measurements for the verification of the CFD model. The room boundaries were controlled at a temperature of 6 degrees C. A measurement set-up was built around 3 church benches which were equipped with the prototype system. The CFD program Fluent 6.1.22 was used. A multi-grid CFD model was built. Equations for flow, turbulence, energy and radiation were solved. The discretization schemes used were: Standard, SIMPLE, and the first order upwind scheme for momentum, turbulence kinetic energy, turbulence dissipation rate and energy. A comparison between the CFD results and the measurements indicated that there is a reasonable agreement when the RNG k-epsilon model was used. It was anticipated that the CFD model of the 3 benches will eventually be merged with the CFD model of the whole church. The CFD models will be further improved by using different viscous models, radiation models and discretization schemes. In addition, grid dependency will be checked. 8 refs., 3 tabs., 14 figs.

  1. LOW MASS FLOW RATE IN FLAT-PLATE LIQUID HEATING SOLAR COLLECTORS

    Directory of Open Access Journals (Sweden)

    Wies?aw Gogó?

    1993-01-01

    Full Text Available Heat transfer problems in flat-plate liquid heating solar collector have been analysed. Some improved collector efficiency criteria have been used. Low mass flow rate (LMFR of working fluid has been shown as an advantageous operating range for solar collector. The serpentine-flow absorber of the particular type has been proposed as an improved construction for LMFR-collector.

  2. Solar thermal electric power systems with line-focus collectors. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Duff, W.S.; Karaki, S.; Shaner, W.W.; Wilbur, P.J.; Somers, E.V.; Grimble, R.E.; Wilson, H.S.; Watt, A.D.

    1978-12-01

    Electric power generation by conventional Rankine cycle heat engines with heat supplied by line-focus solar collectors was investigated. The objectives of the study were: (1) determine which of four types of line-focus solar collectors coupled with turbine-generators of conventional design has the potential to produce low-cost electric power with thermal energy in 100 to 300/sup 0/C range; (2) develop performance and cost relationships for organic Rankine cycle engines for power generation capacities from 3 MW/sub e/ to 300 MW/sub e/; (3) develop conceptual storage units for organic fluid systems. Evaluation procedures and study results and conclusion are presented and discussed in detail. (WHK)

  3. Potential for using parabolic trough collectors to supplement power cycle boilers

    Science.gov (United States)

    Schimmel, W. P., Jr.; Lukens, L. L.

    1981-11-01

    The advantage of such a system is that solar energy is used to heat the water in a steam Rankine cycle device up to the superheat regime, thus displacing the fossil fuel usually required. The temperature associated with this portion of the power cycle is typically on the order of 320 C or less, which makes it compatible with current parabolic trough collector systems. A system model which lends itself to optimization studies was constructed and exercised over a range of the multiparameter space involved. The collector field, storage, supplementary fossil boiler and superheater, and turbine/generator traded off to obtain a series of economically optimal systems for various years and solar fractions.

  4. Study of a new solar adsorption refrigerator powered by a parabolic trough collector

    International Nuclear Information System (INIS)

    This paper presents the study of solar adsorption cooling machine, where the reactor is heated by a parabolic trough collector (PTC) and is coupled with a heat pipe (HP). This reactor contains a porous medium constituted of activated carbon, reacting by adsorption with ammonia. We have developed a model, based on the equilibrium equations of the refrigerant, adsorption isotherms, heat and mass transfer within the adsorbent bed and energy balance in the hybrid system components. From real climatic data, the model computes the performances of the machine. In comparison with other systems powered by flat plate or evacuated tube collectors, the predicted results, have illustrated the ability of the proposed system to achieve a high performance due to high efficiency of PTC, and high flux density of heat pipe

  5. A compact E × B filter: A multi-collector cycloidal focusing mass spectrometer

    Science.gov (United States)

    Blase, Ryan C.; Miller, Greg; Westlake, Joseph; Brockwell, Tim; Ostrom, Nathaniel; Ostrom, Peggy H.; Waite, J. Hunter

    2015-10-01

    A compact E × B mass spectrometer is presented. The mass spectrometer presented is termed a "perfect focus" mass spectrometer as the resolution of the device is independent of both the initial direction and energy of the ions (spatial and energy independent). The mass spectrometer is small in size (˜10.7 in.3) and weight (˜2 kg), making it an attractive candidate for portability when using small, permanent magnets. A multi-collector Faraday cup design allows for the detection of multiple ion beams in discrete collectors simultaneously; providing the opportunity for isotope ratio monitoring. The mass resolution of the device is around 400 through narrow collector slits and the sensitivity of the device follows expected theoretical calculations of the ion current produced in the electron impact ion source. Example mass spectra obtained from the cycloidal focusing mass spectrometer are presented as well as information on mass discrimination based on instrumental parameters and isotope ratio monitoring of certain ion signals in separate Faraday cups.

  6. Visible and infrared absorption spectra of covering materials for solar collectors

    International Nuclear Information System (INIS)

    Use of solar energy increases every year. In Latvia, solar energy is used mainly by solar collectors. The main part of the solar collector is the absorber, but not less important is the covering material which protects the absorber from the cooling impact of the wind. This cover must be transparent for solar radiation, but opaque for thermal radiation of the absorber, which is at greater wavelengths. Therefore it is important to measure absorption spectra of possible covering materials at visible and infrared wavelength ranges. Absorption spectra have been measured for several materials: glass, polythene, Plexiglas, and cells Plexiglas. Absorption spectra for all these materials are measured in three ranges: ultraviolet-visible (UV-VIS): 250-1000 nm; near infrared (NIR): 700-110 nm; infrared (IR): 1200-8000 nm. UV-VIS spectra with the 'Ocean Optics' device HR-4000 have been measured, but NIR and IR - with 'Bruker' Furje spectrometer EQUINOX 55. Evaluation of absorption spectra showed that the most suitable material (from the considered) for covering of solar collectors is Plexiglas

  7. Experimental study on optical properties of the collector

    Energy Technology Data Exchange (ETDEWEB)

    Wang Juan [School of Science, Xi' an Jiaotong Univ., Xi' an (China); Zhao Liang; Li Huashan [State Key Lab. of Multiphase Flow in Power Engineering, Xi' an Jiaotong Univ., Xi' an (China)

    2008-07-01

    Solar collector is one of the most important parts of solar chimney power plant. It plays an important role in improving the efficiency and saving the cost of the whole system. In this paper, several transparent materials which could be used as the collector were chosen to study the optical properties. The materials include polymethyl methacrylate (PMMA), polycarbonate (PC), perspex (PS) and ordinary glass. Firstly, an experiment device was designed with the collector angles varying from 15 to 60 . Secondly, different thickness of glass and different slope angles of the collector of these materials mentioned above on transmittance was compared. The effect of pollutions caused by the natural environment such as dust, rain and aging on these materials was considered in the experiment. Based on the experimental results, a conclusion was made that PMMA has the highest transmittance among the four materials without considering other factors. (orig.)

  8. Glycol/water evacuated-tube solar collector

    Science.gov (United States)

    1980-01-01

    Report describes performance of 8 tube and 10 tube commercially produced solar collectors. Tests include thermal efficiency, time constant for temperature drop after solar flux is cut, change in efficiency with Sun angle, and temperature rise if circulation is stopped.

  9. Electron beam simulation from gun to collector: Towards a complete solution

    Energy Technology Data Exchange (ETDEWEB)

    Mertzig, R., E-mail: robert.mertzig@cern.ch; Shornikov, A., E-mail: robert.mertzig@cern.ch; Wenander, F. [CERN, Geneva 23, CH-1211 (Switzerland); Beebe, E.; Pikin, A. [Brookhaven National Lab, Upton, NY 11973 (United States)

    2015-01-09

    An electron-beam simulation technique for high-resolution complete EBIS/T modelling is presented. The technique was benchmarked on the high compression HEC{sup 2} test-stand with an electron beam current, current density and energy of 10 A, 10 kA/cm{sup 2} and 49.2 keV, and on the immersed electron beam at REXEBIS for electron beam characteristics of 0.4 A, 200 A/cm{sup 2} and 4.5 keV. In both Brillouin-like and immersed beams the electron-beam radius varies from several millimeters at the gun, through some hundreds of micrometers in the ionization region to a few centimeters at the collector over a total length of several meters. We report on our approach for finding optimal meshing parameters, based on the local beam properties such as magnetic field-strength, electron energy and beam radius. This approach combined with dividing the problem domain into sub-domains, and subsequent splicing of the local solutions allowed us to simulate the beam propagation in EBISes from the gun to the collector using a conventional PC in about 24–36 h. Brillouin-like electron beams propagated through the complete EBIS were used to analyze the beam behavior within the collector region. We checked whether elastically reflected paraxial electrons from a Brillouin-like beam will escape from the collector region and add to the loss current. We have also studied the power deposition profiles as function of applied potentials using two electrode geometries for a Brillouin-like beam including the effects of backscattered electrons.

  10. Electron beam simulation from gun to collector: Towards a complete solution

    International Nuclear Information System (INIS)

    An electron-beam simulation technique for high-resolution complete EBIS/T modelling is presented. The technique was benchmarked on the high compression HEC2 test-stand with an electron beam current, current density and energy of 10 A, 10 kA/cm2 and 49.2 keV, and on the immersed electron beam at REXEBIS for electron beam characteristics of 0.4 A, 200 A/cm2 and 4.5 keV. In both Brillouin-like and immersed beams the electron-beam radius varies from several millimeters at the gun, through some hundreds of micrometers in the ionization region to a few centimeters at the collector over a total length of several meters. We report on our approach for finding optimal meshing parameters, based on the local beam properties such as magnetic field-strength, electron energy and beam radius. This approach combined with dividing the problem domain into sub-domains, and subsequent splicing of the local solutions allowed us to simulate the beam propagation in EBISes from the gun to the collector using a conventional PC in about 24–36 h. Brillouin-like electron beams propagated through the complete EBIS were used to analyze the beam behavior within the collector region. We checked whether elastically reflected paraxial electrons from a Brillouin-like beam will escape from the collector region and add to the loss current. We have also studied the power deposition profiles as function of applied potentials using two electrode geometries for a Brillouin-like beam including the effects of backscattered electrons

  11. Performance of solar collectors under low temperature conditions

    DEFF Research Database (Denmark)

    Bunea, Mircea; Eicher, Sara; Hildbrand, Catherine; Bony, Jacques; Perers, Bengt; Citherlet, Stéphane

    2012-01-01

    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 unglaze...

  12. Proceedings of the solar thermal concentrating collector technology symposium

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, B.P.; Kreith, F. (eds.)

    1978-08-01

    The purpose of the symposium was to review the current status of the concentrating collector technology, to disseminate the information gained from experience in operating solar systems, and to highlight the significant areas of technology development that must be vigorously pursued to foster early commercialization of concentrating solar collectors. Separate abstracts were prepared for thirteen invited papers and working group summaries. Two papers were previously abstracted for EDB.

  13. Opensource Software for MLR-Modelling of Solar Collectors

    DEFF Research Database (Denmark)

    Bacher, Peder; Perers, Bengt

    2011-01-01

    A first research version is now in operation of a software package for multiple linear regression (MLR) modeling and analysis of solar collectors according to ideas originating all the way from Walletun et. al. (1986), Perers, (1987 and 1993). The tool has been implemented in the free and open source program R http://www.r-project.org/. Applications of the software package includes: visual validation, resampling and conversion of data, collector performance testing analysis according to the Euro...

  14. Discovery of lithium in copper current collectors used in batteries

    International Nuclear Information System (INIS)

    Aging studies of Li-ion batteries have been concentrated on degradation of cathode, anode and electrolyte materials with very limited attention to degradation in current collectors. Our data shows the presence of lithium beyond the active material and in the copper current collector (CCC). The lithium impurity in the CCC will lead to degradation in its thermal and electrical behavior and thus cannot be ignored for overall efforts in understanding the aging mechanisms predicting the life and performance of the batteries.

  15. Characteristics of collector formation during the rift developmental stage

    Energy Technology Data Exchange (ETDEWEB)

    Demidovich, L.A.

    1977-01-01

    An explanation is given for characteristics of the formation of collector properties in terrigenous and carbonate rock of the Devonian in the rift stage of the Pripyat downwarp development. An interconnection was noted between the paleostructural factor, lithogenesis, and the physical parameters of rocks. A forecast is made of collectors and for future oil and gas operations on the basis of an analysis of these data.

  16. Opensource Software for MLR-Modelling of Solar Collectors

    DEFF Research Database (Denmark)

    Bacher, Peder; Perers, Bengt

    2011-01-01

    A first research version is now in operation of a software package for multiple linear regression (MLR) modeling and analysis of solar collectors according to ideas originating all the way from Walletun et. al. (1986), Perers, (1987 and 1993). The tool has been implemented in the free and open source program R http://www.r-project.org/. Applications of the software package includes: visual validation, resampling and conversion of data, collector performance testing analysis according to the European Standard EN 12975 (Fischer et al., 2004), statistical validation of results, and the determination of collector incidence angle modifiers without the need of a mathematical function (Perers, 1997). The paper gives a demonstration with examples of the applications, based on measurements obtained at a test site at DTU in Denmark (Fan et al., 2009). The tested collector is a single glazed large area flat plate collector with selective absorber and teflon anti convection layer. The package is intended to enable fast and reliable validation of data, and provide a united implementation for MLR testing of solar collectors. This will furthermore make it simple to replicate the calculations by a third party in order to validate the results. Finally more advanced methods can be implemented and easily shared as extensions to the package, for example methods for statistical estimation of the incidence angle modifier with non-linear functions for collectors with more complicated optics. The overall advantage of this kind of tool and analysis is that it is almost the inverse of simulation. Therefore the model and parameters will be very well validated for application in later use for system simulation, even if the test is no real system test. Also for annual collector performance calculations with a new Excel tool connected to EN 12975 (Kovacs, 2011) this built in validation gives an extra quality assurance.

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

    Directory of Open Access Journals (Sweden)

    Venkatesh Reddy

    2013-08-01

    Full Text Available 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 long technical lifetime of a concentrating system, the solar reflectance of the reflectors must be high and long term stable. Therefore, different types of reflector materials and absorbing materials were analyzed in this work; also the optical properties and degradation of the reflecting surfaces were assessed. During the research, focus has shifted from evaluation of the performance of concentrating solar collector to analysis of the optical properties of reflector and absorbing materials. The shift of focus was motivated by the need to assess long term system performance and possibilities of optimizing the optical efficiency or reducing costs by using new types of reflector materials and absorbing materials. For the design of the SPTC frame, a finite element model had been developed and used to check the capability of the structure to absorb torsion and bending forces, under dead and wind loads. The SPTC was fabricated in local workshops and the sun tracking system was assembled using electric and electronic components in the market, while the mechanical components making up the driving system were procured from the second hand market. The fabricated SPTC and its tracking system were tested outdoors in the campus under dry and wet weather. The experimental results obtained have shown that the obtained characteristic curve of the tested Aluminium collector is considerably lower than that of a mirror collector which can be attributed to the higher thermal losses for the lack of the evacuated glass envelope around the absorbing tube, the end losses of the collector and the inaccuracy in tracking the sun. However, the mirror collector efficiency is about 8% higher than that of Aluminium under dry weather condition, which is fairly acceptable, considering that it was the first attempt to manufacture such mirror collector locally. Thus, the overall aim of the INTERNATIONAL JOURNAL OF RESEARCH IN AERONAUTICAL AND MECHANICAL ENGINEERING Vol.1 Issue.4,August 2013. Pgs: 36-55 Pradeep Kumar K V, Srinath T, Venkatesh Reddy 38work presented in this research was to investigate the possibilities to increase the efficiency of the solar energy systems, and thereby reducing the cost of the electricity or heat that was produced. Attention was also given to the long term durability and robustness of the system. The basic hypothesis was that the use of durable, light weight, low cost reflectors for increasing the concentrator efficiency.

  18. Design approaches for solar industrial process-heat systems: nontracking and line-focus collector technologies

    Energy Technology Data Exchange (ETDEWEB)

    Kutscher, C.F.; Davenport, R.L.; Dougherty, D.A.; Gee, R.C.; Masterson, P.M.; May, E.K.

    1982-08-01

    The design methodology for solar industrial process heat systems is described, and an overview is given of the use of solar energy in industry. A way to determine whether solar energy makes sense for a particular application is described. The basic system configurations used to supply hot water or steam are discussed, and computer-generated graphs are supplied that allow the user to select a collector type. Detailed energy calculations are provided, including the effects of thermal losses and storage. The selection of subsystem components is described, and control systems, installation and start-up details, economics, and safety and environmental issues are explained. (LEW)

  19. REVIEW OF PERFORMANCE AND ANALYSIS ISI FLAT PLATE COLLECTOR WITH MODIFIED FLAT PLATE COLLECTOR

    OpenAIRE

    MR.Y.Y.NANDURKAR; R. S. Shelke

    2012-01-01

    The market of solar water heater of natural circulation type (thermo-siphon) is fast growing in India. Initial cost of the solar water heater system at present is high because of store type design. It is necessary to make the product more popular by reducing the cost. This is possible by reducing area of liquid flat plate collector by increasing tube diameter and reducing riser length. Hence it is essential to make solar water heater in affordable range of the general public class. Present w...

  20. Dual curvature acoustically damped concentrating collector. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, G.A.; Rausch, R.A.

    1980-05-01

    A development program was conducted to investigate the design and performance parameters of a novel, dual curvature, concentrating solar collector. The reflector of the solar collector is achieved with a stretched-film reflective surface that approximates a hyperbolic paraboloid and is capable of line-focusing at concentration ratios ranging from 10 to 20X. A prototype collector was designed based on analytical and experimental component trade-off activities as well as economic analyses of solar thermal heating and cooling systems incorporating this type of collector. A prototype collector incorporating six 0.66 x 1.22 m (2 x 4 ft) was fabricated and subjected to a limited thermal efficiency test program. A peak efficiency of 36% at 121/sup 0/C (250/sup 0/F) was achieved based upon the gross aperture area. Commercialization activities were conducted, including estimated production costs of $134.44/m/sup 2/ ($12.49/ft/sup 2/) for the collector assembly (including a local suntracker and controls) and $24.33/m/sup 2/ ($2.26/ft/sup 2/) for the reflector subassembly.

  1. FLOW DISTRIBUTION IN A SOLAR COLLECTOR PANEL WITH HORIZONTAL FINS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan

    2005-01-01

    The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontal fins. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics (CFD) calculations. Further, experimental investigations of a 12.5 m² solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the backside of the absorber tubes. The measured temperatures are compared to the temperatures determined by the CFD model and there is a good similarity between the measured and calculated results. Calculations with the CFD model elucidate the flow and temperature distribution in the collector. The influences of operating conditions such as flow rate, temperature of inlet flow and collector tilt angle are shown. Based on the investigations preliminary recommendations for theoperation of the investigated collector are given. For instance, minimum flow rate in order to avoid boiling in the horizontal strips is recommended.

  2. On the growth of the crops and leaf tissue as affected by increase in UV-B radiant quantities

    International Nuclear Information System (INIS)

    On the assumption of the increase in UV-B radiant quantities in natural light by the ozone layer depletion, the effect of UV radiation on the growth, dry matter production and leaf tissue of crops were investigated. Results obtained are as follows. 1) The growth of dwarf bean, rice plant and cucumber became very inhibited, when UV-B radiant quantities in natural light increased. 2) Especially the effect of the increase of UV-B radiant quantities caused large failure in the growth of the leaf, and the amount of dry matter production lowered. 3) As an effect of UV-B on the tissue of dwarf bean leaf, death of epidermal cell and morphological abnormality of palisade tissue cell were observed. 4) From the result of this study, it was considered that crop production received a very important effect, when UV-B radiant quantities in the natural light increased 20% further than the present

  3. Theoretical and experimental analysis and optimization of semi-transparent solar thermal facade collectors

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, Christoph

    2012-11-01

    This thesis presents a physical model of transparent facade components. It provides a scientific method applicable for a broad range of transparent components as well as the implementation and validation of the method as a new simulation component and the integration into a major simulation environment which is used for many building projects. Absorptance and transmittance values are calculated using angle-dependent polarization-dependent spectral input data. Detailed radiation processing takes into account 236 patches of the unity sphere to calculate the solar transmission and absorption. A one-dimensional thermal model is used to calculate the useful energy gain of the collector and the heat transfer to the interior in every time step. A new coupling method to the building in the TRNSYS environment provides unprecedented accuracy in the simulation of transparent facade components not only for the detailed model, but also for black-box models as presented by (Kuhn et al. 2011) with an implementation in ESP-r. The new TRNSYS implementation of the black-box model even offers higher accuracy than the original ESP-r implementation regarding the treatment of diffuse irradiance. This thesis also presents the measurement methods to characterize each layer of a transparent facade component as well as the processing of the measurement data. It presents validations of the model against validated software, against efficiency measurements of a flat-plate collector, against calorimetric measurements of a glazing unit with integrated blinds and finally, against calorimeter measurements of a transparent collector. Apart from shorter development times and reduced development costs for innovative transparent facade components, the combination of measurements and simulations offers a unique possibility to optimize components. The accuracy of the simulation of the energy flux to the interior and of the collector gain is assessed using Monte Carlo simulations. The requirements on transparent facade components are discussed with a focus on their architectural function and on technical requirements. They provide the boundary conditions for the development of new components. The first prototype of a new transparent solar thermal facade collector is used to validate a new TRNSYS Type which is then assessed in whole-year simulations. The results show that already this prototype leads to primary energy savings even if compared to an opaque wall. This successful integration of visual transparency, energy efficiency and supplied renewable energy makes further optimization of component designs even more interesting. With the new model, the optimum configuration for each site can be calculated. Up to now, transparent facade collectors could not be simulated in any simulation environment. One could try to include the passive gains by solar transmission and secondary heat gains. One can also try to approximate the active collector gains. However, in reality, the passive gains are strongly coupled to the active gains. It was therefore not possible to plan complex building projects - a serious market barrier for innovative products like (ROBIN SUN 2011). This thesis now provides a scientific method for predicting the energy impact of transparent facade components and their indoor surface temperature. It delivers a basis for economic calculations and comparisons between different facade solutions in the area between aesthetic ambitions, ecological responsibility, economic rationale and human comfort.

  4. Experimental study including subjective evaluations of mixing and displacement ventilation combined with radiant floor heating/cooling system

    DEFF Research Database (Denmark)

    Krajcik, Michal; Tomasi, Roberta; Simone, Angela; Olesen, Bjarne W.

    2013-01-01

    Sixteen subjects evaluated the indoor environment in four experiments with different combinations of ventilation systems and radiant heating/cooling systems. In the first two tests, the simulated residential room was equipped either by a mixing ventilation system supplying warm air for space heating or by a combination of radiant floor heating and mixing ventilation system. The vertical air temperature distribution was more uniform for floor heating. The discomfort due to cold feet/lower legs wa...

  5. Radiant Ceiling Panels Combined with Localized Methods for Improved Thermal Comfort of Both Patient and Medical Staff in Patient Room

    DEFF Research Database (Denmark)

    Mori, Sakura; Barova, Mariya; Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Tanabe, Shin-ichi

    2012-01-01

    The objectives were to identify whether ceiling installed radiant heating panels can provide thermal comfort to the occupants in a patient room, and to determine a method for optimal thermal environment to both patient and medical staff simultaneously. The experiments were performed in a climate chamber resembling a single-bed patient room under convective air conditioning alone or combined with the ceiling installed radiant heating panels. Two thermal manikins simulated a patient lying in the b...

  6. AN INVESTIGATION ON PHOTODIODE SWITCHING TIMES FOR PULSED HIGH RADIANT POWERS

    Directory of Open Access Journals (Sweden)

    Erdem ÖZÜTÜRK

    2004-02-01

    Full Text Available In many applications the light impinging on photodiode surface is pulsed. The change in parameter values in the equivalent circuit of photodiode is important if the amplitude of light pulses are large. In this situation, the change of parameter values with the amplitude of light pulse is nonlinear. Because of this, the nonlinear model of photodiode has been used in this search. By the reasons of photoconductive operation mode is a fast operation, the photoconductive circuit has been examined. In this study, according to the nonlinear behavior of photodiode at pulsed high radiant powers the changes of switching times have been investigated by using SPICE program and the changing of switching times with increasing radiant power has been showed.

  7. Numerical evaluation of the thermal performances of roof-mounted radiant barriers

    CERN Document Server

    Miranville, Frédéric; Lucas, Franck; Johan, Seriacaroupin

    2014-01-01

    This paper deals with the thermal performances of roof-mounted radiant barriers. Using dynamic simulations of a mathematical model of a whole test cell including a radiant barrier installed between the roof top and the ceiling, the thermal performance of the roof is calculated. The mean method is more particularly used to assess the thermal resistance of the building component and lead to a value which is compared to the one obtained for a mass insulation product such as polyurethane foam. On a further stage, the thermal mathematical model is replaced by a thermo-aeraulic model which is used to evaluate the thermal resistance of the roof as a function of the airflow rate. The results shows a better performance of the roof in this new configuration, which is widely used in practice. Finally, the mathematical relation between the thermal resistance and the airflow rate is proposed.

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

    Directory of Open Access Journals (Sweden)

    Recep Kulcu

    2008-05-01

    Full Text Available 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 radiation data were estimated using an empirical model in the related literature. Our results showed that high tilt angles during the autumn (September to November and winter (December to February and low tilt angles during the summer (March to August enabled the solar collector surface to absorb the maximum amount of solar radiation. Monthly optimum tilt angles were estimated devising a sinusoidal function of latitude and day of the year, and their validation resulted in a high R2 value of 98.8%, with root mean square error (RMSE of 2.06o.

  9. Electrocatalysis of Lithium Polysulfides: Current Collectors as Electrodes in Li/S Battery Configuration

    Science.gov (United States)

    Babu, Ganguli; Ababtain, Khalid; Ng, K. Y. Simon; Arava, Leela Mohana Reddy

    2015-03-01

    Lithium Sulfur (Li/S) chemistries are amongst the most promising next-generation battery technologies due to their high theoretical energy density. However, the detrimental effects of their intermediate byproducts, polysulfides (PS), have to be resolved to realize these theoretical performance limits. Confined approaches on using porous carbons to entrap PS have yielded limited success. In this study, we deviate from the prevalent approach by introducing catalysis concept in Li/S battery configuration. Engineered current collectors were found to be catalytically active towards PS, thereby eliminating the need for carbon matrix and their processing obligatory binders, additives and solvents. We reveal substantial enhancement in electrochemical performance and corroborate our findings using a detailed experimental parametric study involving variation of several kinetic parameters such as surface area, temperature, current rate and concentration of PS. The resultant novel battery configuration delivered a discharge capacity of 700 mAh g-1 with the two dimensional (2D) planar Ni current collectors and an enhancement in the capacity up to 900 mAh g-1 has been realized using the engineered three dimensional (3D) current collectors. The battery capacity has been tested for stability over 100 cycles of charge-discharge.

  10. Experimental analysis on a novel solar collector system achieved by supercritical CO2 natural convection

    International Nuclear Information System (INIS)

    Highlights: • Supercritical CO2 flow is proposed for natural circulation solar water heater system. • Experimental system established and consists of supercritical fluid high pressure side and water side. • Stable supercritical CO2 natural convective flow is well induced and water heating process achieved. • Seasonal solar collector system efficiency above 60% achieved and optimization discussed. - Abstract: Solar collector has become a hot topic both in scientific research and engineering applications. Among the various applications, the hot water supply demand accounts for a large part of social energy consumption and has become one promising field. The present study deals with a novel solar thermal conversion and water heater system achieved by supercritical CO2 natural circulation. Experimental systems are established and tested in Zhejiang Province (around N 30.0°, E 120.6°) of southeast China. The current system is designed to operate in the supercritical region, thus the system can be compactly made and achieve smooth high rate natural convective flow. During the tests, supercritical CO2 pipe flow with Reynolds number higher than 6700 is found. The CO2 fluid temperature in the heat exchanger can be as high as 80 °C and a stable supply of hot water above 45 °C is achieved. In the seasonal tests, relative high collector efficiency generally above 60.0% is obtained. Thermal and performance analysis is carried out with the experiment data. Comparisons between the present system and previous solar water heaters are also made in this paper

  11. Numerical simulation of solar parabolic trough collector performance in the Algeria Saharan region

    International Nuclear Information System (INIS)

    Highlights: • The parabolic trough collector performance is examined. • The finite difference method is proposed and validated. • Two fluids are considered water and TherminolVP-1™. - Abstract: In order to determine the optical and thermal performance of a solar parabolic trough collector under the climate conditions of Algerian Sahara, a computer program based on one dimensional implicit finite difference method with energy balance approach has been developed. The absorber pipe, glass envelope and fluid were divided into several segments and the partial derivation in the differential equations was replaced by the backward finite difference terms in each segment. Two fluids were considered, liquid water and TherminolVP-1™ synthetic oil. Furthermore, the intensity of the direct solar radiation was estimated by monthly average values of the atmospheric Linke turbidity factor for different tracking systems. According to the simulation findings, the one axis polar East–West and horizontal East–West tracking systems were most desirable for a parabolic trough collector throughout the whole year. In addition, it is found that the thermal efficiency was about 69.73–72.24%, which decreases with the high synthetic oil fluid temperatures and increases in the lower water temperature by 2%

  12. Enhanced Cyclability of Li/Polysulfide Batteries by a Polymer-Modified Carbon Paper Current Collector.

    Science.gov (United States)

    Cui, Yi; Fu, Yongzhu

    2015-09-16

    Lithium-sulfur (Li-S) batteries are considered to be the next-generation rechargeable systems due to their high energy densities and low cost. However, significant capacity decay over cycling is a major impediment for their practical applications. Polysulfides Li2Sx (3 polymers can tune the structure and property of sulfur electrodes, hold polysulfides, and improve cycle life. Herein, we examine a polyvinylpyrrolidone-modified carbon paper (CP-PVP) current collector in Li/polysulfide cells. PVP is soluble in the electrolyte solvent, but shows strong affinity with lithium polysulfides. The retention of polysulfides in the CP-PVP current collector is improved by ?50%, which is measured by a linear sweep voltammetry method. Without LiNO3 additive in the electrolyte, the CP-PVP current collector with 50 ?g of PVP can significantly improve cycling stability with a capacity retention of >90% over 50 cycles at C/10 rate. With LiNO3 additive in the electrolyte, the cell shows a reversible capacity of >1000 mAh g(-1) and a capacity retention of >80% over 100 cycles at C/5 rate. PMID:26305234

  13. High Performance Carbon Nanotube Yarn Supercapacitors with a Surface-Oxidized Copper Current Collector.

    Science.gov (United States)

    Zhang, Daohong; Wu, Yunlong; Li, Ting; Huang, Yin; Zhang, Aiqing; Miao, Menghe

    2015-11-25

    Threadlike linear supercapacitors have demonstrated high potential for constructing fabrics to power electronic textiles (eTextiles). To improve the cyclic electrochemical performance and to produce power fabrics large enough for practical applications, a current collector has been introduced into the linear supercapcitors to transport charges produced by active materials along the length of the supercapacitor with high efficiency. Here, we first screened six candidate metal filaments (Pt, Au, Ag, AuAg, PtCu, and Cu) as current collectors for carbon nanotube (CNT) yarn-based linear supercapacitors. Although all of the metal filaments significantly improved the electrochemical performance of the linear supercapacitor, two supercapacitors constructed from Cu and PtCu filaments, respectively, demonstrate far better electrochemical performance than the other four supercapacitors. Further investigation shows that the surfaces of the two Cu-containing filaments are oxidized by the surrounding polymer electrolyte in the electrode. While the unoxidized core of the Cu-containing filaments remains highly conductive and functions as a current collector, the resulting CuO on the surface is an electrochemically active material. The linear supercapacitor architecture incorporating dual active materials CNT + Cu extends the potential window from 1.0 to 1.4 V, leading to significant improvement to the energy density and power density. PMID:26523943

  14. Fabricación y caracterización de espumas de alúmina para aplicación en quemadores porosos radiantes / Fabrication and characterization of alumina foams for application in radiant porous burners

    Scientific Electronic Library Online (English)

    A.M., Herrera; O., Álvarez; J., Escobar; V., Moreno; A.A.M., Oliveira Jr.; D., Hotza.

    Full Text Available En los quemadores radiantes, la fuente de calor requiere un medio poroso en donde se lleva a cabo la reacción de combustión, que hace más eficiente la transferencia de calor. En este trabajo se realizó un estudio de la reología de la suspensión de alúmina fina, cuyos parámetros de viscosidad y tixot [...] ropía fueron la base para la selección de la formulación más adecuada para la fabricación de espumas cerámicas por el método de réplica. Las espumas poliméricas precursoras presentaron mayor porosidad y permeabilidad, en respuesta a la presencia de paredes finas y 99% de celdas abiertas. La mayor resistencia mecánica a la compresión la obtuvo la formulación con mayor carga de sólidos, bajo las mismas condiciones de prueba. Abstract in english In radiant porous burners, the heat source requires a solid porous matrix where the combustion reaction takes place, in which the heat transfer is performed more efficiently. This work is based on a study of the alumina suspension rheology, where parameters as viscosity and tixotropy were the guide [...] to select the appropriate formulation for the ceramic foam fabrication by the replica method. The precursor polymeric foams presented higher porosity and permeability, due to their thin walls and 99% open cells. The highest mechanical strength under compression was obtained for the formulation with the highest solid fraction, under the same test conditions.

  15. Radiant Floor Cooling Combined with Mixing Ventilation in a Residential Room

    DEFF Research Database (Denmark)

    Krajcik, Michal; Simone, Angela; Tomasi, Roberta; Olesen, Bjarne W.

    2013-01-01

    Mixing air ventilation system is one of the main ventilation concepts applied in residential buildings. The effect of combining the mixing ventilation system with the radiant floor heating has been well established, whereas the validation of using the floor for cooling in summer is still in progress. An experimental laboratory study in a simulated residential room with a seated occupant simulated by a thermal manikin was performed in order to evaluate thermal comfort and ventilation effectivenes...

  16. Comparison of radiant and convective cooling of office room: effect of workstation layout

    DEFF Research Database (Denmark)

    Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Rezgals, Lauris; Lipczynska, Aleksandra; Mustakallio, Panu; Kosonen, Risto; Aho, Ilari

    2014-01-01

    The impact of heat source location (room layout) on the thermal environment generated in a double office room with four cooling ventilation systems - overhead ventilation, chilled ceiling with overhead ventilation, active chilled beam and active chilled beam with radiant panels was measured and compared. The room was furnished with two workstations, two laptops and two thermal manikins resembling occupants. Two heat load levels, design (65 W/m2) and usual (39 W/m2), were generated by adding heat...

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

    DEFF Research Database (Denmark)

    Le Dréau, J.; Heiselberg, P.

    2014-01-01

    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...

  18. Study of thermosiphon and radiant panel passive heating systems for metal buildings

    Energy Technology Data Exchange (ETDEWEB)

    Biehl, F.A.; Schnurr, N.M.; Wray, W.O.

    1983-01-01

    A study of passive-heating systems appropriate for use on metal buildings is being conducted at Los Alamos National Laboratory for the Naval Civil Engineering Laboratory, Port Hueneme, California. The systems selected for study were chosen on the basis of their appropriateness for retrofit applications, although they are also suitable for new construction: simple radiant panels that communicate directly with the building interior and a backflow thermosiphon that provides heat indirectly.

  19. Free of pollution gas - an utopia or attainable goal? Gas radiant burner with a small capacity

    International Nuclear Information System (INIS)

    The firm Viessmann has developed a gas radiant burner for boiler capacities up to 100 kN combusting gas with extremely low pollutant emissions. This is possible since from the reaction zone a considerable part of the combustion heat is delivered through radiation by means of a glowing special steel structure. The theoretical fundamentals are explained by means of considerations regarding the equilibrium and a reaction kinetic numerical model. (orig.)

  20. Optimum pulse duration and radiant exposure for vascular laser therapy of dark port-wine skin: a theoretical study

    International Nuclear Information System (INIS)

    Laser therapy for cutaneous hypervascular malformations such as port-wine stain birthmarks is currently not feasible for dark-skinned individuals. We study the effects of pulse duration, radiant exposure, and cryogen spray cooling (CSC) on the thermal response of skin, using a Monte Carlo based optical-thermal model. Thermal injury to the epidermis decreases with increasing pulse duration during irradiation at a constant radiant exposure; however, maintaining vascular injury requires that the radiant exposure also increase. At short pulse durations, only a minimal increase in radiant exposure is necessary for a therapeutic effect to be achieved because thermal diffusion from the vessels is minimal. However, at longer pulse durations the radiant exposure must be greatly increased. There exists an optimum pulse duration at which minimal damage to the epidermis and significant injury within the targeted vasculature occur. For example, the model predicts optimum pulse durations of approximately 1.5, 6, and 20 ms for vessel diameters of 40, 80, and 120 ?m, respectively. Optimization of laser pulse duration and radiant exposure in combination with CSC may offer a means to treat cutaneous lesions in dark-skinned individuals

  1. Investigations for effect of Al2O3–H2O nanofluid flow rate on the efficiency of direct absorption solar collector

    Directory of Open Access Journals (Sweden)

    Hemant Kumar Gupta

    2015-03-01

    Full Text Available The efficiency of conventional tube? in plate type solar collectors is limited due to higher heat losses for surface based solar energy absorption and indirect transfer of heat from hot absorber surface to working fluid having poor heat transfer properties flowing through tubes. In this paper, a prototype direct absorption solar collector having gross area 1.4 m2 working on volumetric absorption principle is developed to investigate the effect of using Al2O3–H2O nanofluid as heat transfer fluid at different flow rates. Experimentation was carried using distilled water and 0.005% volume fractions of 20 nm size Al2O3 nanoparticles at three flow rates of 1.5, 2 and 2.5 lpm. ASHRAE standard 93-86 was followed for calculation of instantaneous efficiency of solar collector. Use of nanofluid improves the optical and thermo physical properties that result into an increase in the efficiency of the collector in all cases of using nanofluids in place of water. Collector efficiency enhancement of 8.1% and 4.2% has been observed for 1.5 and 2 lpm flow rate of nanofluid respectively. Optimum flow rate of 2.5 and 2 lpm towards maximum collector efficiency have also been observed for water and nanofluid respectively.

  2. Protocol of measurement techniques - Project colored solar collectors

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-08-15

    This illustrated annual report for the Swiss Federal Office of Energy (SFOE) takes a look at work done at the Swiss Federal Institute of Technology in Lausanne, Switzerland, on multi-layer, thin-film interference coatings for solar collector glazing. The correct combinations of refractive indices and film thickness are discussed. The authors state that corresponding multi-layered thin film stacks will have to be realised experimentally in a controlled and reproducible way. New thin film materials are to be tailored to exhibit optimised optical and ageing properties. The development of these coatings is to be based on various measurement techniques, such as spectro-photometry, measurements of total power throughput by means of a solar simulator, spectroscopic ellipsometry, scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The paper provides many examples of typical data and explains which film properties can be inferred from each method and thus describes both the function and purpose of the different measurement techniques.

  3. ATS-F radiant cooler contamination test in a hydrazine thruster exhaust

    Science.gov (United States)

    Chirivella, J. E.

    1973-01-01

    A test was conducted under simulated space conditions to determine the potential thermal degradation of the ATS-F radiant cooler from any contaminants generated by a 0.44-N(0.1-lbf) hydrazine thruster. The radiant cooler, a 0.44-N(0.1-lbf)hydrazine engine, and an aluminum plate simulating the satellite interface were assembled to simulate their flight configuration. The cooler was provided with platinum sensors for measuring temperature, and its surfaces were instrumented with six quartz crystal microbalance units (QCM) to measure contaminant mass deposits. The complete assembly was tested in the molecular sink vacuum facility (Molsink) at the Jet Propulsion Laboratory. This was the first time that a radiant cooler and a hydrazine engine were tested together in a very-high-vacuum space simulator, and this test was the first successful measurement of detectable deposits from hydrazine rocket engine plumes in a high vacuum. The engine was subjected to an accelerated duty cycle of 1 pulse/min, and after 2-hr of operation, the QCMs began to shift in frequency. The tests continued for several days and, although there was considerable activity in the QCMs, the cooler never experienced thermal degradation.

  4. Indoor Air Quality Assessment in a Radiantly Cooled Tropical Building: a Case Study

    Directory of Open Access Journals (Sweden)

    Qi Jie KWONG

    2015-10-01

    Full Text Available Background: Many studies have been conducted to assess the indoor air quality (IAQ of buildings throughout the world because it is closely related to comfort, safety and work productivity of occupants. However, there is still lack of available literature about IAQ in tropical buildings that apply radiant cooling systems in conditioning the indoor air.Methods: This paper reports the results obtained from an IAQ audit that was conducted in a new radiantly cooled building in Malaysia, by focusing on the IAQ and thermal comfort parameters.Results: It was identified that the measured concentration levels for the five indoor air contaminants (CO, CO2, TVOC, formaldehyde and respirable particulates were within the threshold limit values (TLVs specified in the IAQ guidelines. Besides, no significant difference was found between the contaminant levels in each floor of the studied building, and a majority of the respondents did not encounter any form of physical discomfort. There is a risk of condensation problem, judging from the measured RH level.Conclusion: An increase of airflow rate and more dehumidification work in the studied building can be made to improve IAQ and prevention of condensation problem. Nevertheless, these schemes should be implemented carefully to avoid occupants’ discomfort. Relocation of workstations was suggested, especially for the lower floors, which had higher occupancy levels. Keywords: Indoor air quality (IAQ, Radiant cooling systems, IAQ audit, Indoor air contaminants, Condensation 

  5. Evaluation of flat-plate collector efficiency under controlled conditions in a solar simulator

    Science.gov (United States)

    Johnson, S. M.; Simon, F. F.

    1976-01-01

    The measured thermal efficiencies of 35 collectors tested with a solar simulator, along with the correlation equations used to generalize the data, are presented in this report. The single correlation used is shown to apply to all the different types of collectors tested, including one with black paint and one cover, one with a selective surface coating and two covers, and an evacuated-tube collector. The test and correlation technique is also modified by using a shield so that collectors larger than the simulator test area can also be tested. This technique was verified experimentally for a shielded collector for which the collector shielded area was 31% of the solar simulator radiation area. A table lists all the collectors tested, the collector areas, and the experimental constants used to correlate the data for each collector.

  6. A Comparison of the Thermodynamic Efficiency of Vacuum Tube and Flat Plate Solar Collector Systems

    Directory of Open Access Journals (Sweden)

    Juozas Bielskus

    2013-12-01

    Full Text Available The article presents simulation based exergy analysis used for comparing solar thermal systems applied for preparing domestic hot water. The simulation of flat and vacuum tube solar collector systems was performed in TRNSYS simulation environment. A period of one year under Lithuanian climate conditions was chosen. Simulation was performed on 6 min time step resolution by calculating energy and exergy flows and creating balance calculation. Assessment results at system and element levels have been presented as monthly variation in efficiency. The conducted analysis has revealed that the systems designed to cover equal heat energy demand operates in different exergetic efficiencies.Article in Lithuanian

  7. PERFORMANCE OF EVACUATED TUBE SOLAR COLLECTOR USING WATER-BASED TITANIUM OXIDE NANOFLUID

    Directory of Open Access Journals (Sweden)

    M. Mahendran

    2012-12-01

    Full Text Available Experiments are undertaken to determine the efficiency of an evacuated tube solar collector using water-based Titanium Oxide (TiO2 nanofluid at the Pekan Campus (3?32’ N, 103?25’ E, Faculty of Mechanical Engineering, University Malaysia Pahang, for the conversion of solar thermal energy. Malaysia lies in the equatorial zone with an average daily solar insolation of more than 900 W/m², which can reach a maximum of 1200 W/m² for most of the year. Traditionally water is pumped through the collector at an optimum flow rate, for the extraction of solar thermal energy. If the outlet temperature of the water is high, further circulation of the water through the collector is useless. This is due to the low thermal conductivity of water of 0.6 W/m.K compared to metals which is many orders higher. Hence it is necessary to reduce the surface temperature either by pumping water at a higher flow rate or by enhancing the fluid’s properties by the dispersion of nanoparticles. Pumping water at higher flow rates is not advantageous as the overall efficiency of the system is lowered. Liquids in which nanosized particles of metal or their oxides are dispersed in a base liquid such as water are known as 'Nanofluids'. This results in higher values of thermal conductivity compared to the base liquid. The thermal conductivity increases with the concentration and temperature of the nanofluid. The increase in thermal conductivity with temperature is advantageous for application in collectors as the solar insolation varies throughout the day, with a minimum in the morning reaching a maximum at 2.00p.m and reducing thereafter. The efficiency of the collector estimated using a TiO2 nanofluid of 0.3% concentration is about 0.73, compared to water which is about 0.58. The efficiency is enhanced by 16.7% maximum with 30–50nm sized TiO2 nanoparticles dispersed in the water, compared to the system working solely with water. The flow rate is fixed at 2.7 liters per minute for both liquids.

  8. Energy efficient heating and ventilation of large halls

    CERN Document Server

    Hojer, Ondrej; Kabele, Karel; Kotrbaty, Miroslav; Sommer, Klaus; Petras, Dusan

    2011-01-01

    This guidebook is focused on modern methods for design, control and operation of energy efficient heating systems in large spaces and industrial halls. The book deals with thermal comfort, light and dark gas radiant heaters, panel radiant heating, floor heating and industrial air heating systems. Various heating systems are illustrated with case studies. Design principles, methods and modeling tools are presented for various systems.

  9. Development and evaluation of a ceiling ventilation system enhanced by solar photovoltaic thermal collectors and phase change materials

    International Nuclear Information System (INIS)

    Highlights: • A novel ceiling ventilation system enhanced by PVT and PCMs was proposed. • PCM was used to increase the local thermal mass and to serve as a storage unit. • The proposed system can enhance indoor thermal comfort in winter and summer. - Abstract: This paper presents the development and performance evaluation of a novel ceiling ventilation system integrated with solar photovoltaic thermal (PVT) collectors and phase change materials (PCMs). The PVT collectors are used to generate electricity and provide low grade heating and cooling energy for buildings by using winter daytime solar radiation and summer night-time sky radiative cooling, respectively. The PCM is integrated into the building ceiling as a part of the ceiling insulation and at the same time, as a centralized thermal energy storage to temporally store low grade energy collected from the PVT collectors. The performance of the proposed system was numerically evaluated based on a Solar Decathlon house using TRNSYS. The results showed that, in winter conditions, the proposed PVT–PCM integrated ventilation system can significantly improve the indoor thermal comfort of passive buildings without using air-conditioning systems with a maximum air temperature rise of 23.1 °C from the PVT collectors. Compared with the system using PCM but without using PVT collectors, the coefficient of thermal comfort enhancement in the kitchen, dining room and living room of the case building studied using the proposed system improved from almost zero to 0.9823 while the coefficient of thermal comfort enhancement in the study room improved from 0.0060 to 0.9921. In summer conditions, the proposed system can also enhance indoor thermal comfort through night-time sky radiative cooling

  10. Research and Development of a Low Cost Solar Collector

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Asif; Philip, Lee; Thouppuarachchi, Chirath

    2012-08-01

    This is a Final Technical Report on the Research and Development completed towards the development of a Low Cost Solar Collector conducted under the DOE cost-sharing award EE-0003591. The objective of this project was to develop a new class of solar concentrators with geometries and manufacturability that could significantly reduce the fully installed cost of the solar collector field for concentrated solar thermal power plants. The goal of the project was to achieve an aggressive cost target of $170/m2, a reduction of up to 50% in the total installed cost of a solar collector field as measured against the current industry benchmark of a conventional parabolic trough. The project plan, and the detailed activities conducted under the scope of the DOE Award project addressed all major drivers that affect solar collector costs. In addition to costs, the study also focused on evaluating technical performance of new collector architectures and compared them to the performance of the industry benchmark parabolic trough. The most notable accomplishment of this DOE award was the delivery of a full-scale integrated design, manufacturing and field installation solution for a new class of solar collector architecture which has been classified as the Bi-Planar Fresnel Collector (BPFC) and may be considered as a viable alternative to the conventional parabolic trough, as well as the conventional Fresnel collectors. This was in part accomplished through the design and development, all the way through fabrication and test validation of a new class of Linear Planar Fresnel Collector architecture. This architecture offers a number of key differentiating features which include a planar light-weight frame geometry with small mass-manufacturable elements utilizing flat mirror sections. The designs shows significant promise in reducing the material costs, fabrication costs, shipping costs, and on-site field installation costs compared to the benchmark parabolic trough, as well as the conventional Fresnel collector. The noteworthy design features of the BPFC architecture include the use of relatively cheaper flat mirrors and a design which allows the mirror support beam sections to act as load-bearing structural elements resulting in more than a 36% reduction in the overall structural weight compared to an optimized parabolic trough. Also, it was shown that the utilization of small mass-produced elements significantly lowers mass-production and logistics costs that can more quickly deliver economies of scale, even for smaller installations while also reducing shipping and installation costs. Moreover, unlike the traditional Fresnel trough the BPFC architecture does not require complex articulating drive mechanisms but instead utilizes a standard parabolic trough hydraulic drive mechanism. In addition to the development of the Bi-Planar Fresnel Collector, an optimized conventional space-frame type parabolic trough was also designed, built, analyzed and field-tested during the first phase of this award. The design of the conventional space-frame parabolic collector was refined with extensive FEA and CFD analysis to reduce material costs and re-designed for simpler fabrication and more accurate lower-cost field assembly. This optimized parabolic trough represented an improvement over the state-of-the art of the traditional parabolic trough architecture and also served as a more rigorous and less subjective benchmark that was used for comparison of new candidate design architectures. The results of the expanded 1st phase of the DOE award project showed that both the Optimized Parabolic Trough and the new Bi-Planar Fresnel Collector design concepts failed to meet the primary objectives for the project of achieving a 50% cost reduction from the industry reference total installed cost of $350/m2. Results showed that the BPFC came in at projected total installed cost of $237/m2 representing a 32% savings compared to the industry benchmark conventional parabolic trough. And the cost reduction obtained by the Optimized Parabolic Trough compared to the

  11. Atmospheric Ionic Deposition in Tropical Sites of Central Sulawesi Determined by Ion Exchange Resin Collectors and Bulk Water Collector.

    Science.gov (United States)

    Köhler, S; Jungkunst, H F; Gutzler, C; Herrera, R; Gerold, G

    2012-09-01

    In the light of global change, the necessity to monitor atmospheric depositions that have relevant effects on ecosystems is ever increasing particularly for tropical sites. For this study, atmospheric ionic depositions were measured on tropical Central Sulawesi at remote sites with both a conventional bulk water collector system (BWS collector) and with a passive ion exchange resin collector system (IER collector). The principle of IER collector to fix all ionic depositions, i.e. anions and cations, has certain advantages referring to (1) post-deposition transformation processes, (2) low ionic concentrations and (3) low rainfall and associated particulate inputs, e.g. dust or sand. The ionic concentrations to be measured for BWS collectors may easily fall below detection limits under low deposition conditions which are common for tropical sites of low land use intensity. Additionally, BWS collections are not as independent from the amount of rain fallen as are IER collections. For this study, the significant differences between both collectors found for nearly all measured elements were partly correlated to the rainfall pattern, i.e. for calcium, magnesium, potassium and sodium. However, the significant differences were, in most cases, not highly relevant. More relevant differences between the systems were found for aluminium and nitrate (434-484 %). Almost five times higher values for nitrate clarified the advantage of the IER system particularly for low deposition rate which is one particularity of atmospheric ionic deposition in tropical sites of extensive land use. The monthly resolution of the IER data offers new insights into the temporal distribution of annual ionic depositions. Here, it did not follow the tropical rain pattern of a drier season within generally wet conditions. PMID:22865942

  12. Integrated collector storage solar water heater: Temperature stratification

    International Nuclear Information System (INIS)

    An analysis of the temperature stratification inside an Integrated Collector Storage Solar Water Heater (ICS-SWH) was carried out. The system takes the form of a rectangular-shaped box incorporating the solar collector and storage tank into a single unit and was optimised for simulation in Scottish weather conditions. A 3-month experimental study on the ICS-SWH was undertaken in order to provide empirical data for comparison with the computed results. Using a previously developed macro model; a number of improvements were made. The initial macro model was able to generate corresponding water bulk temperature in the collector with a given hourly incident solar radiation, ambient temperature and inlet water temperature and therefore able to predict ICS-SWH performance. The new model was able to compute the bulk water temperature variation in different SWH collectors for a given aspect ratio and the water temperature along the height of the collector (temperature stratification). Computed longitudinal temperature stratification results obtained were found to be in close agreement with the experimental data.

  13. Optimization of solar air collector using genetic algorithm and artificial bee colony algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Sencan Sahin, Arzu [Sueleyman Demirel University, Technology Faculty, Isparta (Turkey)

    2012-11-15

    Thermal performance of solar air collector depends on many parameters as inlet air temperature, air velocity, collector slope and properties related to collector. In this study, the effect of the different parameters which affect the performance of the solar air collector are investigated. In order to maximize the thermal performance of a solar air collector genetic algorithm (GA) and artificial bee colony algorithm (ABC) have been used. The results obtained indicate that GA and ABC algorithms can be applied successfully for the optimization of the thermal performance of solar air collector. (orig.)

  14. Optimization of solar air collector using genetic algorithm and artificial bee colony algorithm

    Science.gov (United States)

    ?encan ?ahin, Arzu

    2012-11-01

    Thermal performance of solar air collector depends on many parameters as inlet air temperature, air velocity, collector slope and properties related to collector. In this study, the effect of the different parameters which affect the performance of the solar air collector are investigated. In order to maximize the thermal performance of a solar air collector genetic algorithm (GA) and artificial bee colony algorithm (ABC) have been used. The results obtained indicate that GA and ABC algorithms can be applied successfully for the optimization of the thermal performance of solar air collector.

  15. Analysis by real-time holographic interferometry of heat transfer at the surface of cold solar collectors

    Science.gov (United States)

    Guerry, J.; Hot, J. P.; Durou, C.

    1980-05-01

    The rate of convective heat transfer at the surface of a solar collector is measured by means of a real-time holographic interferometry system as part of a study of the suitability of cold solar collectors. Holograms were recorded in rapid sequence on photographic plates and continuously on magnetic by the use of a video system for both surfaces of a flat rectangular collector which was heated and cooled to temperatures 20 C above and 10 C below ambient and tilted at various angles of inclination. A zone of laminar flow with a heat transfer coefficient decreasing from 5 to 3.5 W/K per min with distance from the edge of the vertical plate is found, followed by a transition into a turbulent regime in which the heat transfer coefficients remain nearly constant at 3 W/K per min. As the plate is tilted, the heat transfer coefficient on the upper face is observed to exceed that of the lower face, accompanied by greater turbulence on the upper face. Results thus indicate that a 1-sq m collector inclined at 45 deg and maintained at 2 C in a still 12-C atmosphere will collect 70 W of ambient energy by free convection, in addition to the 200 W recoverable from diffuse solar radiation.

  16. Design and dynamic simulation of a novel solar trigeneration system based on hybrid photovoltaic/thermal collectors (PVT)

    International Nuclear Information System (INIS)

    Highlights: ? Sheet and tube photovoltaic/thermal (PVT) solar collector are investigated. ? PVT is integrated in a novel solar trigeneration system. ? The trigeneration system is dynamically investigated for a mediterranean climate. ? PVT performance is excellent during the summer. ? During the winter PVT thermal energy significantly decreases. - Abstract: In this paper, a Solar Heating and Cooling (SHC) system including photovoltaic/thermal (PVT) collectors is considered, implementing a novel polygeneration system producing electricity, space heating and cooling and domestic hot water. In particular, PVT collectors operating up to 80 °C are considered. A case study for a university building located in Naples (Italy) is developed and discussed. The system is mainly composed by: PVT collectors, a single-stage LiBr–H2O absorption chiller, storage tanks and auxiliary heaters. The system also includes additional balance-of-plant devices: heat exchangers, pumps, controllers, cooling tower, etc. The PVT produces electricity which is utilized in part by the building lights and equipments and in part by the system parasitic loads; the rest is eventually sold to the grid. Simultaneously, the PVT system provides the heat required to drive the absorption chiller. The system performance is analyzed from both energetic and economic points of view by means of a zero-dimensional transient simulation model, developed with TRNSYS. The economic results show that the system under investigation can be profitable, provided that an appropriate funding policy is available. In addition, the overall energetic and economic results are comparable to those reported in literature for similar systems.

  17. Optical and thermal evaluations of a medium temperature parabolic trough solar collector used in a cooling installation

    International Nuclear Information System (INIS)

    Highlights: • Medium temperature parabolic trough solar collector for cooling. • Optical evaluations using photogrammetric technique. • Parabolic reflector surface deformation and slope errors identifications. • Intercept factor determination. • Thermal performance of the parabolic trough medium temperature evaluations. - Abstract: Concentrated solar power technology constitute an interesting option to meet a part of future energy demand, especially when considering the high levels of solar radiation and clearness index that are available particularly in Tunisia. In this work, we study a medium temperature parabolic trough solar collector used to drive a cooling installation located at the Center of Researches and Energy Technologies (CRTEn, Bordj-Cedria, Tunisia). Optical evaluations of the collectors using photogrammetric techniques were performed. The analysis and readjustments of the optical results were conducted using a Matlab code. Therefore, slope errors ranged from ?3 to +27 milliradian and the height deviations from the ideal shapes of the parabolic trough collector were 2.5 mm in average with a maximum of 7.5 mm. The intercept factor was determined using both the method of the total optical errors and the camera target method leading respectively to 0.62 and 0.7. Thus, the values of the overall optical efficiency were 0.48 and 0.514. Conversely, a thermal performance testing of the parabolic trough collector was conducted leading to the thermal efficiency and the heat losses evaluations. The instantaneous thermal efficiency reached a maximum of 0.43 but it did not exceed the value of 0.30 when the reflector becomes dirty by dust deposition. This study was also an opportunity for suggesting some recommendations for the enhancement of the PTC performances

  18. Dimensioning, construction and commissioning of a coffee beans drying system with use of solar collectors

    International Nuclear Information System (INIS)

    A system of low-cost solar drying of coffee beans is dimensioned, built and commissioned by using solar collectors based on recycled aluminum cans. The information is collected from literature about the drying of coffee, types of drying and the various types of solar dryers.The coffee beans drying system is conceptualized and sized based on a solar collector constructed of aluminum cans as solar radiation absorbing material. The grain drying system is then built in coffee benefit CoopeTarrazu to all provided by the company and help materials and labor facilities. A guide to implementation of solar drying technology with general information is tailored to implement, select, build and maintain a solar grain dryer in Central America. The launch of the drying system was made by checking the proper functioning of the system and measurement instruments variables selected to calculate the efficiency of the system. The drying system is tested with a load of 45 kg of coffee bean, using a flow of air through natural convection to operate the system with the exclusive use of renewable energy. The grain is drying from a humidity of 50% (b.n), up to a humidity between 11% and 13% (b.n), which is the range generally used for the safe storage of grain. Facts of solar radiation, temperature, air velocity, relative humidity and grain humidity were taken to determine the behavior of the sized system. The maximum thermal efficiency achieved by the solar collector is determined constructed of 18%, with an air flow of 0.013 kg/s and a solar radiation 1138 W/m2. The average drying efficiency during experimentation was 17.8%, which is among the range of efficiencies for the type of drying equipment. Best thermal efficiencies were obtained from the solar collector built that the commercial solar collector compared. Controlling the flow of air into the equipment is recommended in order to improve the thermal efficiency and drying equipment, using blowers, fans or induced draft chimney. (author)

  19. Low cost bare-plate solar air collector

    Science.gov (United States)

    Maag, W. L.; Wenzler, C. J.; Rom, F. E.; Vanarsdale, D. R.

    1980-09-01

    A low cost, bare plate solar collector for preheating ambient air was developed. This type of solar heating system would be applicable for preheating ventilation air for public buildings or other commercial and industrial ventilation requirements. Two prototype collectors were designed, fabricated and installed into an instrumented test system. Tests were conducted for a period of five months. Results of the tests showed consistent operating efficiencies of 60 percent or greater with air preheat temperature uses up to 20 degrees for one of the prototypes. The economic analyses indicated that this type of solar system was economically viable. For the materials of construction and the type of fabrication and installation perceived, costs for the bare plate solar collector are attainable. Applications for preheating ventilation air for schools were evaluated and judged to be economically viable.

  20. Application of activated charcoal radon collectors in high humidity environments.

    Science.gov (United States)

    Iimoto, Takeshi; Tokonami, Shinji; Morishita, Yasuaki; Kosako, Toshiso

    2005-01-01

    Most commercially based activated charcoal radon collectors were designed for use in indoor environments. However, at present, they are often used for research in radon surveys in unique environments, such as in the bathrooms, underground areas, mines, caves and tunnels. In these environments, the relative humidity would be around 100%, and a change in the sensitivity of cpm(Bq m(-3))(-1)(radon) would occur. For this study, the reduction in the sensitivity of activated charcoal radon collector due to environmental humidity was investigated, and the data correction was discussed. Here, ST-100 (Pico-Rad) was selected as an example of a familiar activated charcoal radon collector. According to our performance test, the humidity of 90% (20 degrees C) resulted in a 15% reduction of the sensitivity for 24 h collection. The ST-100 user should discuss the necessity of data correction by comparing the change of sensitivity with other levels of estimation errors. PMID:15465180

  1. Transient response of a concentric evacuated tubular solar collector

    Science.gov (United States)

    Al-Khalil, Kamel M.; Jakubowski, Gerald S.; Springman, Richard A.

    The transient and the steady state performances of an evacuated coaxial tubular solar collector were investigated. A purely implicit central finite differencing numerical technique was used to determine the time-varying temperature distributions in the collector components as well as the fluid exit temperature. Experimental indoor transient tests were conducted in which step inputs of insolation were used. Close agreeement between the experimental and the theoretical results was obtained. The computer model was found to be useful to carry out a complete parametric study. The latter showed that the fluid flow rate had the largest effect on the performance of the collector tube. Lower flow rates resulted in lower efficiencies and longer response times.

  2. Four Interstellar Dust Candidates from the Stardust Interstellar Dust Collector

    Science.gov (United States)

    Westphal, A. J.; Allen, C.; Bajt, S.; Bechtel, H. A.; Borg, J.; Brenker, F.; Bridges, J.; Brownlee, D. E.; Burchell, M.; Burghammer, M.; Butterworth, A. L.; Cloetens, P.; Davis, A. M.; Floss, C.; Flynn, G. J.; Fougeray, P.; Frank, D.; Gainsforth, Z.; Grun, E.; Heck, P. R.; Jillier, J. K.; Hoppe, P.; Howard, L.; Hudson, B.; Huss, G. R.

    2011-01-01

    In January 2006, the Stardust sample return capsule returned to Earth bearing the first solid samples from a primitive solar system body, Comet 81P/Wild2, and a collector dedicated to the capture and return of contemporary interstellar dust. Both collectors were approx. 0.1 sq m in area and were composed of aerogel tiles (85% of the collecting area) and aluminum foils. The Stardust Interstellar Dust Collector (SIDC) was exposed to the interstellar dust stream for a total exposure factor of 20 sq m/day. The Stardust Interstellar Preliminary Examination (ISPE) is a consortium-based project to characterize the collection using nondestructive techniques. The goals and restrictions of the ISPE are described . A summary of analytical techniques is described.

  3. Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response

    Energy Technology Data Exchange (ETDEWEB)

    Troussel, Ph.; Villette, B.; Oudot, G.; Tassin, V. [CEA/DAM/DIF, Bruyères le Châtel, 91297 Arpajon (France); Emprin, B. [CEA/DAM/DIF, Bruyères le Châtel, 91297 Arpajon (France); Laboratoire Charles Fabry, Institut d’Optique, CNRS, University Paris-Sud, 2, Avenue Augustin Fresnel, RD128, 91127 Palaiseau Cedex (France); Bridou, F.; Delmotte, F. [Laboratoire Charles Fabry, Institut d’Optique, CNRS, University Paris-Sud, 2, Avenue Augustin Fresnel, RD128, 91127 Palaiseau Cedex (France); Krumrey, M. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany)

    2014-01-15

    CEA implemented an absolutely calibrated broadband soft X-ray spectrometer called DMX on the Omega laser facility at the Laboratory for Laser Energetics (LLE) in 1999 to measure radiant power and spectral distribution of the radiation of the Au plasma. The DMX spectrometer is composed of 20 channels covering the spectral range from 50 eV to 20 keV. The channels for energies below 1.5 keV combine a mirror and a filter with a coaxial photo-emissive detector. For the channels above 5 keV the photoemissive detector is replaced by a conductive detector. The intermediate energy channels (1.5 keV < photon energy < 5 keV) use only a filter and a coaxial detector. A further improvement of DMX consists in flat-response X-ray channels for a precise absolute measurement of the photon flux in the photon energy range from 0.1 keV to 6 keV. Such channels are equipped with a filter, a Multilayer Mirror (MLM), and a coaxial detector. We present as an example the development of channel for the gold M emission lines in the photon energy range from 2 keV to 4 keV which has been successfully used on the OMEGA laser facility. The results of the radiant power measurements with the new MLM channel and with the usual channel composed of a thin titanium filter and a coaxial detector (without mirror) are compared. All elements of the channel have been calibrated in the laboratory of the Physikalisch-Technische Bundesanstalt, Germany's National Metrology Institute, at the synchrotron radiation facility BESSY II in Berlin using dedicated well established and validated methods.

  4. Liquid metal current collectors for high-speed rotating machinery

    International Nuclear Information System (INIS)

    Recent interest in superconducting motors and generators has created a renewed interest in homopolar machinery. Homopolar machine designs have always been limited by the need for compact, high-current, low-voltage, sliding electrical curent collectors. Conventional graphite-based solid brushes are inadequate for use in homopolar machines. Liquid metals, under certain conditions of relative sliding velocities, electrical currents, and magnetic fields are known to be capable of performing well in homopolar machines. An effort to explore the capabilities and limits of a tongue-and-groove style current collector, utilizing sodium-potassium eutectic alloy (NaK) as the working fluid in high sliding speed operation is reported here. A double current collector generator model with a 14.5-cm maximum rotor diameter, 20,000 rpm rotational capability, and electrical current carrying ability was constructed and operated successfully at a peripheral velocity of 125 m/s. The limiting factor in these experiments was a high-speed fluid-flow instability resulting in the ejection of the working fluid from the operating portions of the collectors. The effects of collector size and geometry, working fluid (NaK or water), and cover gas pressure are reported. Hydrodynamic frictional torque-speed curves are given for the two fluids and for several geometries. Electrical resistances as a function of peripheral velocity at 60 amperes are reported, and the phenomenology of the high-speed fluid-flow instabilities is discussed. The possibility of long-term high-speed operation of current collectors of the tongue-and-groove type, along with experimental and theoretical hydrodynamic friction losses at high peripheral velocities, is considered

  5. Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response

    Science.gov (United States)

    Troussel, Ph.; Villette, B.; Emprin, B.; Oudot, G.; Tassin, V.; Bridou, F.; Delmotte, F.; Krumrey, M.

    2014-01-01

    CEA implemented an absolutely calibrated broadband soft X-ray spectrometer called DMX on the Omega laser facility at the Laboratory for Laser Energetics (LLE) in 1999 to measure radiant power and spectral distribution of the radiation of the Au plasma. The DMX spectrometer is composed of 20 channels covering the spectral range from 50 eV to 20 keV. The channels for energies below 1.5 keV combine a mirror and a filter with a coaxial photo-emissive detector. For the channels above 5 keV the photoemissive detector is replaced by a conductive detector. The intermediate energy channels (1.5 keV Bundesanstalt, Germany's National Metrology Institute, at the synchrotron radiation facility BESSY II in Berlin using dedicated well established and validated methods.

  6. Tracking local control of a parabolic trough collector

    International Nuclear Information System (INIS)

    In the local control, the sun position related to the trough collector is measured by two photo-resistors. The provided electronic signal is then compared with reference levels in order to get a set of B logical signals which form a byte. This byte and the commands issued by a programmable controller are connected to the inputs of o P.R.O.M. memory which is programmed with the logical equations of the control system. The memory output lines give the control command of the parabolic trough collector motor. (Author)

  7. A note on critical ?ow section in collector channels

    Indian Academy of Sciences (India)

    Subhasish Dey

    2001-10-01

    Generalized solution for the location of critical ?ow section in collector channels is presented. Based on the concept of the singularity, the dynamic equation of spatially varied ?ow (SVF) is solved using the ?ow resistance equations of von Karman (for rough regime) and Jain (for transitional and smooth regimes). The advantage of using Jain’s equations is that they provide the explicit forms of the Colebrook-White and Nikuradse equations. Computational steps for the determination of critical ?ow section in a collector channel, being dependent on channel geometry, roughness, longitudinal bed slope and in?ow discharge, are given for different channel shapes.

  8. Theoretical flow investigations of an all glass evacuated tubular collector

    DEFF Research Database (Denmark)

    Shah, Louise Jivan; Furbo, Simon

    2007-01-01

    Heat transfer and flow structures inside all glass evacuated tubular collectors for different operating conditions are investigated by means of computational fluid dynamics. The investigations are based on a collector design with horizontal tubes connected to a vertical 14 manifold channel. Three different tube lengths varying from 0.59 in to 1.47 in have been modelled with five different inlet mass flow rates varying from 0.05 kg/min to 10 kg/min with a constant inlet temperature of 333 K. Unde...

  9. Studies of impurity recycling by the collector probe technique

    International Nuclear Information System (INIS)

    In order to study recycling effects of the nonintrinsic impurity Li discharges with and without LiD-pellet injection were investigated. The observed maximum impurity level of Li in the SOL plasma of discharges without injection reaches less than 10% of that observed in discharges with injection. The measurements offer the possibility to distinguish between influxes from the wall and those which reach the collector probe via the core plasma. The time evolution, orientation and radial dependence of the impurity fluxes are characteristic features of their origin. The consideration of all these features facilitates a better understanding of collector probe measurements in the SOL-plasma. (orig.)

  10. Concentrating solar collector system for the evaporation of low-level radioactive waste water

    International Nuclear Information System (INIS)

    The Los Alamos National Laboratory has recently been awarded a grant under the Solar Federal Buildings Program to design, construct, and operate a high-temperature solar energy system for the processing of low-level radioactive waste water. Conceptual design studies have been completed, and detailed design work is under way for a solar system to produce process heat to evaporate 38,000 gal (143,830 L) of waste water per month. The system will use approximately 11,000 ft2 (1022 m2) of concentrating parabolic trough collectors operating at about 5000F (2620C). Construction of the system is anticipated to begin in 1981. Performance optimization of collector array size and configuration, storage medium and capacity, system operation, and control schemes are done using the active solar system simulator in the DOE-2 building energy analysis computer program. Results of this optimization are reported. This project represents a unique application of solar energy to an increasingly significant problem area in the energy field

  11. 22.5% efficient silicon heterojunction solar cell with molybdenum oxide hole collector

    Science.gov (United States)

    Geissbühler, Jonas; Werner, Jérémie; Martin de Nicolas, Silvia; Barraud, Loris; Hessler-Wyser, Aïcha; Despeisse, Matthieu; Nicolay, Sylvain; Tomasi, Andrea; Niesen, Bjoern; De Wolf, Stefaan; Ballif, Christophe

    2015-08-01

    Substituting the doped amorphous silicon films at the front of silicon heterojunction solar cells with wide-bandgap transition metal oxides can mitigate parasitic light absorption losses. This was recently proven by replacing p-type amorphous silicon with molybdenum oxide films. In this article, we evidence that annealing above 130 °C—often needed for the curing of printed metal contacts—detrimentally impacts hole collection of such devices. We circumvent this issue by using electrodeposited copper front metallization and demonstrate a silicon heterojunction solar cell with molybdenum oxide hole collector, featuring a fill factor value higher than 80% and certified energy conversion efficiency of 22.5%.

  12. PERFORMANCE OF EVACUATED TUBE SOLAR COLLECTOR USING WATER-BASED TITANIUM OXIDE NANOFLUID

    OpenAIRE

    M. Mahendran; Lee, G. C.; Sharma, K V; A. Shahrani; R. A. Bakar

    2012-01-01

    Experiments are undertaken to determine the efficiency of an evacuated tube solar collector using water-based Titanium Oxide (TiO2) nanofluid at the Pekan Campus (3?32’ N, 103?25’ E), Faculty of Mechanical Engineering, University Malaysia Pahang, for the conversion of solar thermal energy. Malaysia lies in the equatorial zone with an average daily solar insolation of more than 900 W/m², which can reach a maximum of 1200 W/m² for most of the year. Traditionally water is pumped through the coll...

  13. A total cost perspective on use of polymeric materials in solar collectors – Importance of environmental performance on suitability

    International Nuclear Information System (INIS)

    Highlights: • A polymeric solar collector system was compared with two traditional ones. • It was found the best in terms of climatic performance per solar heat collected. • The differences in climatic cost between the systems compared however are small. • The low climatic cost makes solar heating better compared to natural gas heating. • Use of Ecoindicator 99 for environmental cost makes solar heating even better. - Abstract: To assess the suitability of solar collector systems in which polymeric materials are used versus those in which more traditional materials are used, a case study was undertaken. In this case study a solar heating system with polymeric solar collectors was compared with two equivalent but more traditional solar heating systems: one with flat plate solar collectors and one with evacuated tube solar collectors. To make the comparison, a total cost accounting approach was adopted. The life cycle assessment (LCA) results clearly indicated that the polymeric solar collector system is the best as regards climatic and environmental performance when they are expressed in terms of the IPPC 100 a indicator and the Ecoindicator 99, H/A indicator, respectively. In terms of climatic and environmental costs per amount of solar heat collected, the differences between the three kinds of collector systems were small when compared with existing energy prices. With the present tax rates, it seems unlikely that the differences in environmental and climatic costs will have any significant influence on which system is the most favoured, from a total cost point of view. In the choice between a renewable heat source and a heat source based on the use of a fossil fuel, the conclusion was that for climatic performance to be an important economic factor, the tax or trade rate of carbon dioxide emissions must be increased significantly, given the initial EU carbon dioxide emission trade rate. The rate would need to be at least of the same order of magnitude as the general carbon dioxide emission tax rate used in Sweden. If environmental costs took into account not only the greenhouse effect but also other mechanisms for damaging the environment as, for example, the environmental impact factor Ecoindicator 99 does, the viability of solar heating versus that of a natural gas heating system would be much higher

  14. An energy recovery system for a quasi-optical gyrotron

    International Nuclear Information System (INIS)

    Design of a depressed collector system for a quasi-optical gyrotron, which had a severe constraint on the maximum allowable radius of the collector region is outlined. The needs for unwinding of spent beam and for energy sorting could be accommodated by precise control of the magnetic field profile, especially in the collector region. Techniques used for defining and obtaining such profiles; and for dovetailing the profile with the collector geometry are discussed. Results on profiles and electron trajectories are presented, which demonstrate the feasibility of the design. From primary electron trajectories a collector efficiency of up to 68% has been calculated for a three collector design. 3 refs., 3 figs

  15. Topical radiant heating in wound healing: an experimental study in a donor site wound model*.

    Science.gov (United States)

    Khan, Aadil A; Banwell, Paul E; Bakker, Martijn C; Gillespie, Patrick G; McGrouther, Douglas A; Roberts, Anthony H N

    2004-12-01

    The importance of temperature in the wound-healing process is rapidly being recognised as a novel way in which to manipulate the wound-healing environment. In this study, we aimed to investigate the direct effect of topical radiant heating (TRH), using a novel bandaging system (Warm-Up, Arizant Health care Inc., Eden Prairie MN, USA; Augustine Medical, USA), on wound healing at a physiological and cellular level. Experimental bandages were positioned over split-thickness skin graft donor site wounds of 12 patients undergoing graft harvesting from the anterior thigh. The experimental group (n=6) underwent intermittent heating for 5 hours (three 1-hour heating cycles at 38 degrees C, separated by two 1-hour rest periods), whilst the control group (n=6) received no radiant heating. Physiological blood-flow recordings both in the control group and the topical radiant heat cohort were undertaken using Laser Doppler Imaging (LDI). Skin biopsies were obtained at identical time points, and immunohistochemical analysis was undertaken using antibodies against neutrophils (NP57), lymphocytes (CD3) and macrophages (CD68). We found that TRH significantly increased local dermal blood flow (P<0.001) by up to 100% in both injured and intact skin. Furthermore, this increase in flow was associated with a significant (P<0.05) increase in CD3 immunoreactivity on day 1 postoperatively. This study demonstrates that TRH increases local blood flow and lymphocyte (CD3) extravasation, and we postulate that these changes may enhance local innate immunity within the healing wound environment. PMID:16722872

  16. A review of the criteria for people exposure to radiant heat flux from fires

    International Nuclear Information System (INIS)

    The NFPA 59A Standard and the Federal Regulation, 49 CFR Part 193, stipulate a level of 5 kW/m2 as the criterion for determining the hazard distance to people exposure from a LNG fire. Another regulation (24CFR, Section 51.204) while stipulating a lower exposure limit of 1.42 kW/m2 provides administrative relief from the regulation if mitigation measures are provided. Several countries in Europe and the Far East have adopted both a specified heat flux value (generally, 5 kW/m2) as well as modified dose criteria for human exposure hazard calculation in risk assessments. In some cases, the regulations in Europe require the use of lower values for children and physically challenged persons. This paper reviews the available literature on the phenomenon of skin burn caused by radiant heat exposure. The associated thermal and spectral properties of human skin are reviewed. The basis for regulatory setting, of 5 kW/m2 and other exposure criteria (as a part of hazard and risk calculations) for evaluating distances to hazards from the exposure of people to radiant heat effects of large fires, is evaluated. An example calculation is provided to show the extent of reduction in the hazard distance to specified radiant heat flux from a fire when the spectral reflection and absorption properties of skin are considered with and without the inclusion of the mitigating effects of clothing. The results indicate that hazard distances calculated including the reflective and band absorptive properties (in IR wavelength) of skin results in a reduction of between 30 and 50% in the hazard distances obtained with current methodology, which ignores these effects. Unfortunately, there are no test results, from full-scale human-exposure-to-IR radiation, with which these predictions can be compared

  17. EVALUATION OF EVACUATED TUBULAR SOLAR COLLECTORS FOR LARGE SDHW SYSTEMS AND COMBINED SPACE HEATING SYSTEMS

    DEFF Research Database (Denmark)

    Qin, Lin; Furbo, Simon

    1999-01-01

    In the present study, detailed investigations on evacuated tubular solar collectors for large solarheating systems have been carried out. Four types of evacuated tubular solar collectors were used in theinvestigation. Based on laboratory tests, simulation models for the collectors were determined. Based on thesemodels, the thermal performance of large solar domestic hot water (DHW) systems and combined domestichot water and space heating systems with the four evacuated tubular collectors was det...

  18. Thermal and Electrical Performance Evaluation of PV/T Collectors in UAE

    OpenAIRE

    Kaya (Çev.), Mustafa

    2013-01-01

    Photovoltaic Thermal/Hybrid collectors are an emerging technology that combines PV and solar thermal collectors by producing heat and electricity simultaneously. In this paper, thermal and electrical performance of PV/T collectors are analyzed and presented for the climate of RAK, UAE. Thermal performance evaluation is done following the collector output model presented in European standard EN 12975-2 and electrical performance evaluation is done by analyzing the effect of water circulation o...

  19. Hybrid PV-thermal collector development: Concepts, experiences, results and research needs

    OpenAIRE

    Fortuin, S.; Hermann, M; Stryi-Hipp, G.; Nitz, P.; Platzer, W.

    2014-01-01

    This paper highlights research on aspects underlying PVT collector development, from which possible design concepts and development paths are determined. Test results from several performance improvements to PVT collector prototypes are presented, culminating in a thermal performance in open circuit mode which is similar to that of a good solar thermal collector. This collector prototype incorporates the required "fail-safe" stagnation protection feature. Remaining material and construction r...

  20. The Effect of the Volume Flow rate on the Efficiency of a Solar Collector

    DEFF Research Database (Denmark)

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

    2006-01-01

    The flow distribution inside a collector panel with an area of 12.5 m² and with 16 parallel connected horizontal fins and the effect of the flow nonuniformity on the risk of boiling and on the collector efficiency have been theoretically and experimentally investigated for different volume flow rates. Theoretically, a simplified model of the solar collector panel is built by means of the CFD (Computational Fluid Dynamics) code Fluent, where the geometry of the collector panel except the casing i...

  1. Experimental Validation and Model Verification for a Novel Geometry ICPC Solar Collector

    DEFF Research Database (Denmark)

    Perers, Bengt; Duff, William S.; Daosukho, Jirachote

    2012-01-01

    A novel geometry ICPC solar collector was developed at the University of Chicago and Colorado State University. A ray tracing model has been designed to investigate the optical performance of both the horizontal and vertical fin versions of this collector. Solar radiation is modeled as discrete uniform rays. Rays falling on the collector are followed as they are attenuated by various components of the collector until they are absorbed by the fin or escape. The extent to which each absorbed ray i...

  2. VALIDATION OF SIMULATION MODELS FOR DIFFERENTLY DESIGNED HEAT-PIPE EVACUATED TUBULAR COLLECTORS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Dragsted, Janne; Furbo, Simon

    2007-01-01

    Differently designed heat-pipe evacuated tubular collectors have been investigated theoretically and experimentally. The theoretical work has included development of two TRNSYS [1] simulation models for heat-pipe evacuated tubular collectors utilizing solar radiation from all directions. One model is developed for heat-pipe evacuated tubular collectors with flat fins and one model is developed for heat-pipe evacuated tubular collectors with curved fins. The models are characterized by detailed c...

  3. Microwave-enhanced electroanalytical processes: generator-collector voltammetry at paired gold electrode junctions.

    OpenAIRE

    Rassaei, L.; French, RW; Compton, RG; Marken, F.

    2009-01-01

    Generator-collector electrode systems allow redox processes and reaction intermediates from multi-step electrode reactions to be monitored. Analytically, collector electrode current responses are insightful and highly sensitive due to (i) the absence of capacitive current components and (ii) an enhanced current response due to 'feedback' between generator and collector electrode. Here, a symmetric gold-gold junction grown by controlled electro-deposition is employed for generator-collector vo...

  4. Concept design and formation of a lithium bromide–water cooling system powered by supercritical CO2 solar collector

    International Nuclear Information System (INIS)

    Highlights: • Supercritical CO2 solar collector is proposed for double effect lithium bromide–water absorption cooling system. • Coupled system concept designs are made to provide sustainable cooling capacity. • Experimental system established and tested for supercritical fluid high pressure cycle side. • Seasonal solar power lithium bromide–water cooling system COP is identified up to 1.08. - Abstract: In this study, concept design and tests for the combination of a supercritical CO2 solar collector powered LiBr–H2O refrigeration system has been investigated. The system is basically consisted of one supercritical CO2 solar collector system and one double effect lithium bromide–water absorption refrigeration cycle. The assessment of the overall performance is based on the theoretical analysis of the refrigeration cycle and experiments on a supercritical solar collector system in Shaoxing City, Zhejiang Province of China. Energy balance and seasonal efficiency analysis are developed in this study. The maximum daily averaged COP (Coefficient of Performance) of the proposed system is estimated up to 1.08, while the averaged COP ranges from 0.53 to 0.91 for different months. The obtained results indicate considerable improvement to conventional solar-assisted cooling systems. In addition, it is also found that this system performs better than traditional systems even when the solar radiation is not at high level, which is due to the stability and high efficiency of supercritical circulation collector cycle proposed. The system feasibility and possible future directions of the proposed system are also discussed in detail in this study. It is hoped that the current results can be of help to related system designs

  5. Perceived air quality, thermal comfort, and SBS symptoms at low air temperature and increased radiant temperature

    DEFF Research Database (Denmark)

    Toftum, Jørn; Reimann, Gregers Peter; Foldbjerg, P.; Clausen, Geo; Fanger, Povl Ole

    2002-01-01

    This study investigated if low air temperature, which is known to improve the perception of air quality, also can reduce the intensity of some SBS symptoms. In a low-polluting office, human subjects were exposed to air at two temperatures 23 deg.C and 18 deg.C both with and without a pollution source present at the low temperature. To maintain overall thermal neutrality, the low air temperature was partly compensated for by individually controlled radiant heating, and partly by allowing subjects...

  6. Three dimensional modelling and numerical analysis of super-radiant harmonic emission in FEL (optical klystron)

    International Nuclear Information System (INIS)

    A full 3-D Analysis of super-radiant (bunched electron) free electron harmonic radiation is presented. A generalized form of the FEL pendulum equation was derived and numerically solved. Both spectral and phasor formulation were developed to treat the radiation in the time domain. In space the radiation field is expanded in terms of either a set of free space discrete modes or plane waves. The numerical solutions reveal some new distinctly 3-D effects to which we provide a physical explanation. 12 refs., 9 figs., 5 tabs

  7. Efficiency of solar collectors at varying wind velocities; Solfangeres effektivitet ved forskellige vindhastigheder

    Energy Technology Data Exchange (ETDEWEB)

    Froesig Jensen, F.

    1995-01-01

    The aim was to investigate the efficiency of solar collectors at various velocities of wind passing over their surfaces. Solar collectors with the trade names Agena, Arcon and Aidt were studied. It was found that there was a significant relation between the efficiency of the collectors and the wind speed. Wind correction factors were established, based on measurements taken and relevant theories. (AB)

  8. Design and installation package for the Sunmat Flat Plate Solar Collector

    Energy Technology Data Exchange (ETDEWEB)

    1978-03-01

    The information used in evaluating the design of the Sunmat Liquid Flat Plat Plate Solar Collector developed by Calmac Manufacturing Company is presented. Included in this package are the Subsystem Performance Specification, Installation, Operation and Maintenance Manuals, collector sizing guides, and detailed drawings of the single-glazed collector.

  9. FLOW DISTRIBUTION IN A SOLAR COLLECTOR PANEL WITH HORIZONTAL ABSORBER STRIPS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Shah, Louise Jivan

    2007-01-01

    The objective of this work is to theoretically and experimentally investigate the flow and temperature distribution in a solar collector panel with an absorber consisting of horizontal strips. Fluid flow and heat transfer in the collector panel are studied by means of computational fluid dynamics (CFD) calculations. Further, experimental investigations of a 12.5 m² solar collector panel with 16 parallel connected horizontal fins are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the backside of the absorber tubes. The measured temperatures are compared to the temperatures determined by the CFD model and there is a good similarity between the measured and calculated results. Calculations with the CFD model elucidate the flow and temperature distribution in the collector. The influences of different operating conditions such as flow rate, properties of solar collector fluid, solar collector fluid inlet temperature and collector tilt angle are shown. The flow distribution through the absorber fins is uniform if high flow rates are used. By decreased flow rate and decreased content of glycol in the glycol/water mixture used as solar collector fluid, and by increased collector tilt and inlet temperature, the flow distribution gets worse resulting in a decreased collector efficiency and an increased risk of boiling in the upper part of the collector panel. Keywords: Solar collector; Flow distribution; Computational Fluid Dynamics (CFD); Buoyancy effects

  10. A comparative analysis of configurations of linear Fresnel collectors for concentrating solar power

    International Nuclear Information System (INIS)

    Linear Fresnel collector arrays present some relevant advantages in the domain of concentrating solar power because of their simplicity, robustness and low capital cost. However, they also present important drawbacks and limitations, notably their average concentration ratio, which seems to limit significantly the performance of these systems. First, the paper addresses the problem of characterizing the mirror field configuration assuming hourly data of a typical year, in reference to a configuration similar to that of Fresdemo. For a proper comparative study, it is necessary to define a comparison criterion. In that sense, a new variable is defined, the useful energy efficiency, which only accounts for the radiation that impinges on the receiver with intensities above a reference value. As a second step, a comparative study between central linear Fresnel reflectors and compact linear Fresnel reflectors is carried out. This analysis shows that compact linear Fresnel reflectors minimize blocking and shading losses compared to a central configuration. However this minimization is not enough to overcome other negative effects of the compact Fresnel collectors, as the greater dispersion of the rays reaching the receiver, caused by the fact that mirrors must be located farther from the receiver, which yields to lower efficiencies. - Highlights: • An optical optimization of linear Fresnel collectors has been done. • The useful energy efficiency accounts for incident radiation and its concentration. • A comparative study between central Fresnel and compact Fresnel is carried out. • Compact Fresnel minimizes blocking/shading losses compared to central Fresnel. • This minimization does not overcome the greater dispersion of the rays in the receiver

  11. Evaluation of Single-Pass Photovoltaic-Thermal Air Collector with Rectangle Tunnel Absorber

    Directory of Open Access Journals (Sweden)

    Goh L. Jin

    2010-01-01

    Full Text Available Problem statement: Photovoltaic solar cell generate electric by receiving sun light or solar irradiance. But solar cell received heat from solar irradiance as well and this will reduced the efficiency of the solar cell. The heat trap at the solar photovoltaic panel become waste energy. Approach: The solution for this was by adding a cooling system to the photovoltaic panel. The purpose of this study was to cool the solar cell in order to increase its electrical efficiency and also to produce heat energy in the form of hot air. Hot air can be used for drying applications. A single pass PVT with rectangle tunnel absorber has been developed. The rectangle tunnel acted as an absorber and was located at the back side of a standard photovoltaic panel. The dimension of the photovoltaic panel was 120×53 cm. The size of the rectangle tunnel was 27 units of tunnel bar with the size of 1.2×2.5×120 cm (width×tall×length and 12 units with 1.2×2.5×105.3 cm (width×tall×length. The rectangle tunnel was connected in parallel. The PVT collector has been tested using a solar simulator. Results: Electrical efficiency increased when the solar cell was cool by air flow. Solar photovoltaic thermal collector with rectangle tunnel absorber has better electrical and thermal efficiency compared to solar collector without rectangle tunnel absorber. Photovoltaic, thermal and combined photovoltaic thermal efficiency of 10.02, 54.70 and 64.72% at solar irradiance of 817.4 W m-2, mass flow rate of 0.0287 kg sec-1 at ambiant temperature of 25°C respectively has been obtained. Conclusion: The hybrid photovoltaic and thermal with rectangle tunnel as heat absorber shows higher performance compared to conventional PV/T system.

  12. Certification and verification for calmac flat plate solar collector

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-27

    This document contains information used in the certification and verification of the Calmac Flat Plate Collector. Contained are such items as test procedures and results, information on materials used, Installation, Operation, and Maintenance Manuals, and other information pertaining to the verification and certification.

  13. EUV near normal incidence collector development at SAGEM

    Science.gov (United States)

    Mercier Ythier, R.; Bozec, X.; Geyl, R.; Rinchet, A.; Hecquet, Christophe; Ravet-Krill, Marie-Françoise; Delmotte, Franck; Sassolas, Benoît; Flaminio, Raffaele; Mackowski, Jean-Marie; Michel, Christophe; Montorio, Jean-Luc; Morgado, Nazario; Pinard, Laurent; Roméo, Elodie

    2008-03-01

    Through its participation to European programs, SAGEM has worked on the design and manufacturing of normal incidence collectors for EUV sources. By opposition to grazing incidence, normal incidence collectors are expected to collect more light with a simpler and cheaper design. Designs are presented for the two current types of existing sources: Discharge Produced Plasma (DPP) and Laser Produced Plasma (LPP). Collection efficiency is calculated in both cases. It is shown that these collectors can achieve about 10 % efficiency for DPP sources and 40 % for LPP sources. SAGEM works on the collectors manufacturability are also presented, including polishing, coating and cooling. The feasibility of polishing has been demonstrated with a roughness better than 2 angstroms obtained on several materials (glass, silicon, Silicon Carbide, metals...). SAGEM is currently working with the Institut d'Optique and the Laboratoire des Materiaux Avancés on the design and the process of EUV coatings for large mirrors. Lastly, SAGEM has studied the design and feasibility of an efficient thermal control, based on a liquid cooling through slim channels machined close to the optical surface.

  14. Upper airway inflammation and respiratory symptoms in domestic waste collectors

    OpenAIRE

    Wouters, I.; Hilhorst, S; Kleppe, P; Doekes, G; Douwes, J.; Peretz, C; Heederik, D

    2002-01-01

    Objectives: To compare respiratory symptoms and upper airway inflammation in domestic waste collectors and controls, and to find the association between measures of upper airway inflammation on the one hand and exposure concentrations of organic dust or respiratory symptoms on the other hand.

  15. Liquid metal current collector applications and material compatibility

    International Nuclear Information System (INIS)

    The objective of this paper has been to summarize briefly the material considerations involved in the development of liquid metal current collectors for homopolar machinery applications. A significant amount of data in this regard has been obtained over the last several years by individual researchers for NaK exposure conditions. However, NaK material compatibility data over the entire time and temperature range of interest is highly desirable. At DTNSRDC, a 300 kW superconducting homopolar motor and generator are under test, both utilizing free surface tongue-and-groove current collectors with NaK as the working fluid. In addition to demonstrating the feasibility of other aspects of machine design, the intention is to use these machines as vehicles for testing of the several liquid metal current collector concepts which are considered worthwhile candidates for incorporation in future full-scale machines. It is likely that the optimal collector approach for a large low speed motor may be quite different from that for a smaller high speed generator, possibly involving the use of different liquid metals

  16. Seismic measurement in Ostrava´s collector Centrum.

    Czech Academy of Sciences Publication Activity Database

    Stolárik, Martin

    Ostrava : Ústav geoniky AV ?R, 2006 - (Blaheta, R.; Kolcun, A.), s. 45-48 ISBN 80-86407-11-X. [Ph.D. Workshop 2006 /1./. Ostrava (CZ), 08.11.2006-08.11.2006] Institutional research plan: CEZ:AV0Z30860518 Keywords : collector * accelerometer Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  17. Evaluation of solar collectors for heat pump applications. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Skartvedt, Gary; Pedreyra, Donald; McMordle, Dr., Robert; Kidd, James; Anderson, Jerome; Jones, Richard

    1980-08-01

    The study was initiated to evaluate the potential utility of very low cost (possibly unglazed and uninsulated) solar collectors to serve as both heat collection and rejection devices for a liquid source heat pump. The approach consisted of exercising a detailed analytical simulation of the complete heat pump/solar collector/storage system against heating and cooling loads derived for typical single-family residences in eight US cities. The performance of each system was measured against that of a conventional air-to-air heat pump operating against the same loads. In addition to evaluation of solar collector options, the study included consideration of water tanks and buried pipe grids to provide thermal storage. As a supplement to the analytical tasks, the study included an experimental determination of night sky temperature and convective heat transfer coefficients for surfaces with dimensions typical of solar collectors. The experiments were conducted in situ by placing the test apparatus on the roofs of houses in the Denver, Colorado, area. (MHR)

  18. Evacuated-tube solar collector--performance evaluation

    Science.gov (United States)

    1980-01-01

    Report gives thermal performance test procedures and results for commercially produced, water-filled, 8-tube collectors. Tests include efficiency, time constant for temperature drop after solar flux is cut, change in efficiency as function of sun angle, and test to see if tubes break when filled with hot water.

  19. Evaluation of an evacuated-tube liquid solar collector

    Science.gov (United States)

    1981-01-01

    Indoor and outdoor thermal performances of collectors are compared in report. Tests conducted on indoor solar simulator with data from both diffuse and specular reflectors are presented graphically and in tables. Comparisons with previous data for prototype show effects of improved mainfold.

  20. Modified Evacuated-Tube Collector Tested in Solar Simulator

    Science.gov (United States)

    1982-01-01

    According to report, particular commercial evacuated-tube solar collector performs slightly more efficiently with larger manifold. Tests were performed with Marshall Space Flight Center solar simulator. Report describes test conditions and procedures, provides analysis of results, and presents tables and graphs of data, both measured and calculated.