Radiative cooling and broadband phenomenon in low-frequency waves

Institute of Scientific and Technical Information of China (English)

无

2000-01-01

In this paper, we analyze the effects of radiative cooling on the pure baroclinic low-frequency waves under the approximation of equatorial -plane and semi-geostrophic condition. The results show that radiative cooling does not, exclusively, provide the damping effects on the development of low-frequency waves. Under the delicate radiative-convective equilibrium, radiative effects will alter the phase speed and wave period, and bring about the broadband of phase velocity and wave period by adjusting the vertical profiles of diabatic heating. when the intensity of diabatic heating is moderate and appropriate, it is conductive to the development and sustaining of the low-frequency waves and their broadband phenomena, not the larger, the better. The radiative cooling cannot be neglected in order to reach the moderate and appropriate intensity of diabatic heating.

Passive-solar directional-radiating cooling system

Science.gov (United States)

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

1985-06-27

A radiative cooling system for use with an ice-making system having a radiating surface aimed at the sky for radiating energy at one or more wavelength bands for which the atmosphere is transparent and a cover thermally isolated from the radiating surface and transparent at least to the selected wavelength or wavelengths, the thermal isolation reducing the formation of condensation on the radiating surface and/or cover and permitting the radiation to continue when the radiating surface is below the dewpoint of the atmosphere, and a housing supporting the radiating surface, cover and heat transfer means to an ice storage reservoir.

Passive radiative cooling below ambient air temperature under direct sunlight.

Science.gov (United States)

Raman, Aaswath P; Anoma, Marc Abou; Zhu, Linxiao; Rephaeli, Eden; Fan, Shanhui

2014-11-27

Cooling is a significant end-use of energy globally and a major driver of peak electricity demand. Air conditioning, for example, accounts for nearly fifteen per cent of the primary energy used by buildings in the United States. A passive cooling strategy that cools without any electricity input could therefore have a significant impact on global energy consumption. To achieve cooling one needs to be able to reach and maintain a temperature below that of the ambient air. At night, passive cooling below ambient air temperature has been demonstrated using a technique known as radiative cooling, in which a device exposed to the sky is used to radiate heat to outer space through a transparency window in the atmosphere between 8 and 13 micrometres. Peak cooling demand, however, occurs during the daytime. Daytime radiative cooling to a temperature below ambient of a surface under direct sunlight has not been achieved because sky access during the day results in heating of the radiative cooler by the Sun. Here, we experimentally demonstrate radiative cooling to nearly 5 degrees Celsius below the ambient air temperature under direct sunlight. Using a thermal photonic approach, we introduce an integrated photonic solar reflector and thermal emitter consisting of seven layers of HfO2 and SiO2 that reflects 97 per cent of incident sunlight while emitting strongly and selectively in the atmospheric transparency window. When exposed to direct sunlight exceeding 850 watts per square metre on a rooftop, the photonic radiative cooler cools to 4.9 degrees Celsius below ambient air temperature, and has a cooling power of 40.1 watts per square metre at ambient air temperature. These results demonstrate that a tailored, photonic approach can fundamentally enable new technological possibilities for energy efficiency. Further, the cold darkness of the Universe can be used as a renewable thermodynamic resource, even during the hottest hours of the day.

Radiation detector system having heat pipe based cooling

Science.gov (United States)

Iwanczyk, Jan S.; Saveliev, Valeri D.; Barkan, Shaul

2006-10-31

A radiation detector system having a heat pipe based cooling. The radiation detector system includes a radiation detector thermally coupled to a thermo electric cooler (TEC). The TEC cools down the radiation detector, whereby heat is generated by the TEC. A heat removal device dissipates the heat generated by the TEC to surrounding environment. A heat pipe has a first end thermally coupled to the TEC to receive the heat generated by the TEC, and a second end thermally coupled to the heat removal device. The heat pipe transfers the heat generated by the TEC from the first end to the second end to be removed by the heat removal device.

Hand-held, mechanically cooled, radiation detection system for gamma-ray spectroscopy

Science.gov (United States)

Burks, Morgan Thomas; Eckels, Joel Del

2010-06-08

In one embodiment, a radiation detection system is provided including a radiation detector and a first enclosure encapsulating the radiation detector, the first enclosure including a low-emissivity infra-red (IR) reflective coating used to thermally isolate the radiation detector. Additionally, a second enclosure encapsulating the first enclosure is included, the first enclosure being suspension mounted to the second enclosure. Further, a cooler capable of cooling the radiation detector is included. Still yet, a first cooling interface positioned on the second enclosure is included for coupling the cooler and the first enclosure. Furthermore, a second cooling interface positioned on the second enclosure and capable of coupling the first enclosure to a cooler separate from the radiation detection system is included. Other embodiments are also presented.

SELF-CONVERGENCE OF RADIATIVELY COOLING CLUMPS IN THE INTERSTELLAR MEDIUM

International Nuclear Information System (INIS)

Yirak, Kristopher; Frank, Adam; Cunningham, Andrew J.

2010-01-01

Isolated regions of higher density populate the interstellar medium (ISM) on all scales-from molecular clouds, to the star-forming regions known as cores, to heterogeneous ejecta found near planetary nebulae and supernova remnants. These clumps interact with winds and shocks from nearby energetic sources. Understanding the interactions of shocked clumps is vital to our understanding of the composition, morphology, and evolution of the ISM. The evolution of shocked clumps is well understood in the limiting 'adiabatic' case where physical processes such as self-gravity, heat conduction, radiative cooling, and magnetic fields are ignored. In this paper, we address the issue of evolution and convergence when one of these processes-radiative cooling-is included. Numeric convergence studies demonstrate that the evolution of an adiabatic clump is well captured by roughly 100 cells per clump radius. The presence of radiative cooling, however, imposes limits on the problem due to the removal of thermal energy. Numerical studies which include radiative cooling typically adopt the 100-200 cells per clump radius resolution. In this paper, we present the results of a convergence study for radiatively cooling clumps undertaken over a broad range of resolutions, from 12 to 1536 cells per clump radius, employing adaptive mesh refinement (AMR) in a two-dimensional axisymmetric geometry (2.5 dimensions). We also provide a fully three-dimensional simulation, at 192 cells per clump radius, which supports our 2.5 dimensional results. We find no appreciable self-convergence at ∼100 cells per clump radius as small-scale differences owing to increasingly resolving the cooling length have global effects. We therefore conclude that self-convergence is an insufficient criterion to apply on its own when addressing the question of sufficient resolution for radiatively cooled shocked clump simulations. We suggest the adoption of alternate criteria to support a statement of sufficient

Performance limit of daytime radiative cooling in warm humid environment

Directory of Open Access Journals (Sweden)

Takahiro Suichi

2018-05-01

Full Text Available Daytime radiative cooling potentially offers efficient passive cooling, but the performance is naturally limited by the environment, such as the ambient temperature and humidity. Here, we investigate the performance limit of daytime radiative cooling under warm and humid conditions in Okayama, Japan. A cooling device, consisting of alternating layers of SiO2 and poly(methyl methacrylate on an Al mirror, is fabricated and characterized to demonstrate a high reflectance for sunlight and a selective thermal radiation in the mid-infrared region. In the temperature measurement under the sunlight irradiation, the device shows 3.4 °C cooler than a bare Al mirror, but 2.8 °C warmer than the ambient of 35 °C. The corresponding numerical analyses reveal that the atmospheric window in λ = 16 ∼ 25 μm is closed due to a high humidity, thereby limiting the net emission power of the device. Our study on the humidity influence on the cooling performance provides a general guide line of how one can achieve practical passive cooling in a warm humid environment.

Energy Savings Potential of Radiative Cooling Technologies

Energy Technology Data Exchange (ETDEWEB)

Fernandez, Nicholas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Weimin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Alvine, Kyle J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Katipamula, Srinivas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-11-30

Pacific Northwest National Laboratory (PNNL), with funding from the U.S. Department of Energy’s (DOE’s) Building Technologies Program (BTP), conducted a study to estimate, through simulation, the potential cooling energy savings that could be achieved through novel approaches to capturing free radiative cooling in buildings, particularly photonic ‘selective emittance’ materials. This report documents the results of that study.

Control of dew and frost formation on leaf by radiative cooling

International Nuclear Information System (INIS)

Matsui, T.; Eguchi, H.; Mori, K.

1981-01-01

A radiative cooling system was developed to control dew and frost formations and to examine the effect of the radiative cooling on the leaf temperature. The growth chamber was provided with a box which was constructed by using heat insulating materials to minimize the disturbances and to regulate the air current. A cooling coil (cooling surface of 300 cm was equipped at the bottom of the box and manipulated by a refrigerator of 1, 430 kcal hour -1 , and a concave mirror was attached to the ceiling of the box to facilitate the reflection of the radiation from the leaf to the cooling coil. The moisture in air was supplied by flowing the controlled air (0.2 m min -1 ) into the box. The distribution of dew point temperatures was almost uniform horizontally even under vertically slight conversion (downward velocity of 1.3 cm sec -1 ) of the air. The leaf temperature became about 1.0°C lower than the ambient air temperature under the radiative cooling. The dew and the frost were clearly observed on the leaf after the time when the leaf temperature had become lower than the dew point temperature. The dew increased in size in course of time, and the frost varied in shape and in size with the temperatures. Thus, artificial formations of the dew and the frost were made possible by the radiative cooling system developed in this experiment

Thermal computations for electronics conductive, radiative, and convective air cooling

CERN Document Server

Ellison, Gordon

2010-01-01

IntroductionPrimary mechanisms of heat flowConductionApplication example: Silicon chip resistance calculationConvectionApplication example: Chassis panel cooled by natural convectionRadiationApplication example: Chassis panel cooled only by radiation 7Illustrative example: Simple thermal network model for a heat sinked power transistorIllustrative example: Thermal network circuit for a printed circuit boardCompact component modelsIllustrative example: Pressure and thermal circuits for a forced air cooled enclosureIllustrative example: A single chip package on a printed circuit board-the proble

Scalable-manufactured randomized glass-polymer hybrid metamaterial for daytime radiative cooling

Science.gov (United States)

Zhai, Yao; Ma, Yaoguang; David, Sabrina N.; Zhao, Dongliang; Lou, Runnan; Tan, Gang; Yang, Ronggui; Yin, Xiaobo

2017-03-01

Passive radiative cooling draws heat from surfaces and radiates it into space as infrared radiation to which the atmosphere is transparent. However, the energy density mismatch between solar irradiance and the low infrared radiation flux from a near-ambient-temperature surface requires materials that strongly emit thermal energy and barely absorb sunlight. We embedded resonant polar dielectric microspheres randomly in a polymeric matrix, resulting in a metamaterial that is fully transparent to the solar spectrum while having an infrared emissivity greater than 0.93 across the atmospheric window. When backed with a silver coating, the metamaterial shows a noontime radiative cooling power of 93 watts per square meter under direct sunshine. More critically, we demonstrated high-throughput, economical roll-to-roll manufacturing of the metamaterial, which is vital for promoting radiative cooling as a viable energy technology.

Development of a single-phase thermosiphon for cold collection and storage of radiative cooling

Energy Technology Data Exchange (ETDEWEB)

Zhao, Dongliang; Martini, Christine Elizabeth; Jiang, Siyu; Ma, Yaoguang; Zhai, Yao; Tan, Gang; Yin, Xiaobo; Yang, Ronggui

2017-11-01

A single-phase thermosiphon is developed for cold collection and storage of radiative cooling. Compared to the conventional nocturnal radiative cooling systems that use an electric pump to drive the heat transfer fluid, the proposed single-phase thermosiphon uses the buoyancy force to drive heat transfer fluid. This solution does not require electricity, therefore improving the net gain of the radiative cooling system. A single-phase thermosiphon was built, which consists of a flat panel, a cold collection tank, a water return tube, and a water distribution tank. Considering that outdoor radiative cooling flux is constantly changing (i.e. uncontrollable), an indoor testing facility was developed to provide a controllable cooling flux (comparable to a radiative cooling flux of 100 W/m2) for the evaluation of thermosiphon performance. The testing apparatus is a chilled aluminum flat plate that has a controlled air gap separation relative to the flat panel surface of the thermosiphon to emulate radiative cooling. With an average of 105 W/m2 cooling flux, the 18 liters of water in the thermosiphon was cooled to an average temperature of 12.5 degrees C from an initial temperature of 22.2 degrees C in 2 h, with a cold collection efficiency of 96.8%. The results obtained have demonstrated the feasibility of using a single-phase thermosiphon for cold collection and storage of radiative cooling. Additionally, the effects of the thermosiphon operation conditions, such as tilt angle of the flat panel, initial water temperature, and cooling energy flux, on the performance have been experimentally investigated. Modular design of the single-phase thermosiphon gives flexibility for its scalability. A radiative cooling system with multiple thermosiphon modules is expected to play an important role in cooling buildings and power plant condensers.

Measurements of plasma rotation in an axially magnetized MPD arc-jet

Energy Technology Data Exchange (ETDEWEB)

Tobari, Hiroyuki; Ashino, Masashi; Yoshino, Kyohei; Sagi, Yukiko; Yoshinuma, Mikirou; Hattori, Kunihiko; Ando, Akira; Inutake, Masaaki [Department of Electrical Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi (Japan)

2001-01-24

Characteristics of an axially magnetized MPD (magneto-plasma-dynamic) arcjet plasma are investigated by spectroscopy on the HITOP (High density of Tohoku Plasma) device in Tohoku University. Plasma flow and rotational velocity and temperature of He ion and atom near the muzzle region of MPD arcjet are measured by Doppler shift and broadening of the HeI ({lambda}=578.56 nm) and HeII ({lambda}=468.58 nm) lines. From the measured radial profile of rotational velocity and temperature of He ion, the radial profiles of electrical field and space potential are calculated and it has been found that the potential profile in the core region is parabolic, which shows the plasma rotates as a rigid body. (author)

Feasibility of flow studies at NICA/MPD

Energy Technology Data Exchange (ETDEWEB)

Geraksiev, N. S., E-mail: nikolay.geraksiev@gmail.com [Plovdiv University “Paisii Hilendarski”, FPET (Bulgaria); Collaboration: MPD Collaboration

2015-12-15

In the light of recent developments in heavy ion physic, anisotropic flow measurements play a key role in a better understanding of the hot and dense barionic matter. In the presented article a short introduction to the proposed NICA/MPD project is given, as well as a brief description of the event-plane method used to estimate the elliptic flow of reconstructed and identified hadrons (p, π, Λ)

Stratocumulus Cloud Top Radiative Cooling and Cloud Base Updraft Speeds

Science.gov (United States)

Kazil, J.; Feingold, G.; Balsells, J.; Klinger, C.

2017-12-01

Cloud top radiative cooling is a primary driver of turbulence in the stratocumulus-topped marine boundary. A functional relationship between cloud top cooling and cloud base updraft speeds may therefore exist. A correlation of cloud top radiative cooling and cloud base updraft speeds has been recently identified empirically, providing a basis for satellite retrieval of cloud base updraft speeds. Such retrievals may enable analysis of aerosol-cloud interactions using satellite observations: Updraft speeds at cloud base co-determine supersaturation and therefore the activation of cloud condensation nuclei, which in turn co-determine cloud properties and precipitation formation. We use large eddy simulation and an off-line radiative transfer model to explore the relationship between cloud-top radiative cooling and cloud base updraft speeds in a marine stratocumulus cloud over the course of the diurnal cycle. We find that during daytime, at low cloud water path (CWP correlated, in agreement with the reported empirical relationship. During the night, in the absence of short-wave heating, CWP builds up (CWP > 50 g m-2) and long-wave emissions from cloud top saturate, while cloud base heating increases. In combination, cloud top cooling and cloud base updrafts become weakly anti-correlated. A functional relationship between cloud top cooling and cloud base updraft speed can hence be expected for stratocumulus clouds with a sufficiently low CWP and sub-saturated long-wave emissions, in particular during daytime. At higher CWPs, in particular at night, the relationship breaks down due to saturation of long-wave emissions from cloud top.

2-Methyl-2,4-pentanediol (MPD boosts as detergent-substitute the performance of ß-barrel hybrid catalyst for phenylacetylene polymerization

Directory of Open Access Journals (Sweden)

Julia Kinzel

2017-07-01

Full Text Available Covering hydrophobic regions with stabilization agents to solubilize purified transmembrane proteins is crucial for their application in aqueous media. The small molecule 2-methyl-2,4-pentanediol (MPD was used to stabilize the transmembrane protein Ferric hydroxamate uptake protein component A (FhuA utilized as host for the construction of a rhodium-based biohybrid catalyst. Unlike commonly used detergents such as sodium dodecyl sulfate or polyethylene polyethyleneglycol, MPD does not form micelles in solution. Molecular dynamics simulations revealed the effect and position of stabilizing MPD molecules. The advantage of the amphiphilic MPD over micelle-forming detergents is demonstrated in the polymerization of phenylacetylene, showing a ten-fold increase in yield and increased molecular weights.

Radiative cooling of relativistic electron beams

International Nuclear Information System (INIS)

Huang, Z.

1998-05-01

Modern high-energy particle accelerators and synchrotron light sources demand smaller and smaller beam emittances in order to achieve higher luminosity or better brightness. For light particles such as electrons and positrons, radiation damping is a natural and effective way to obtain low emittance beams. However, the quantum aspect of radiation introduces random noise into the damped beams, yielding equilibrium emittances which depend upon the design of a specific machine. In this dissertation, the author attempts to make a complete analysis of the process of radiation damping and quantum excitation in various accelerator systems, such as bending magnets, focusing channels and laser fields. Because radiation is formed over a finite time and emitted in quanta of discrete energies, he invokes the quantum mechanical approach whenever the quasiclassical picture of radiation is insufficient. He shows that radiation damping in a focusing system is fundamentally different from that in a bending system. Quantum excitation to the transverse dimensions is absent in a straight, continuous focusing channel, and is exponentially suppressed in a focusing-dominated ring. Thus, the transverse normalized emittances in such systems can in principle be damped to the Compton wavelength of the electron, limited only by the Heisenberg uncertainty principle. In addition, he investigates methods of rapid damping such as radiative laser cooling. He proposes a laser-electron storage ring (LESR) where the electron beam in a compact storage ring repetitively interacts with an intense laser pulse stored in an optical resonator. The laser-electron interaction gives rise to rapid cooling of electron beams and can be used to overcome the space charge effects encountered in a medium energy circular machine. Applications to the designs of low emittance damping rings and compact x-ray sources are also explored

Radiative cooling of relativistic electron beams

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhirong [Stanford Univ., CA (United States)

1998-05-01

Modern high-energy particle accelerators and synchrotron light sources demand smaller and smaller beam emittances in order to achieve higher luminosity or better brightness. For light particles such as electrons and positrons, radiation damping is a natural and effective way to obtain low emittance beams. However, the quantum aspect of radiation introduces random noise into the damped beams, yielding equilibrium emittances which depend upon the design of a specific machine. In this dissertation, the author attempts to make a complete analysis of the process of radiation damping and quantum excitation in various accelerator systems, such as bending magnets, focusing channels and laser fields. Because radiation is formed over a finite time and emitted in quanta of discrete energies, he invokes the quantum mechanical approach whenever the quasiclassical picture of radiation is insufficient. He shows that radiation damping in a focusing system is fundamentally different from that in a bending system. Quantum excitation to the transverse dimensions is absent in a straight, continuous focusing channel, and is exponentially suppressed in a focusing-dominated ring. Thus, the transverse normalized emittances in such systems can in principle be damped to the Compton wavelength of the electron, limited only by the Heisenberg uncertainty principle. In addition, he investigates methods of rapid damping such as radiative laser cooling. He proposes a laser-electron storage ring (LESR) where the electron beam in a compact storage ring repetitively interacts with an intense laser pulse stored in an optical resonator. The laser-electron interaction gives rise to rapid cooling of electron beams and can be used to overcome the space charge effects encountered in a medium energy circular machine. Applications to the designs of low emittance damping rings and compact x-ray sources are also explored.

Directional radiative cooling thermal compensation for gravitational wave interferometer mirrors

Energy Technology Data Exchange (ETDEWEB)

Justin Kamp, Carl [Department of Chemical Reaction Engineering, Chalmers University of Technology, SE-412 96 Goteborg (Sweden)], E-mail: carl.kamp@chalmers.se; Kawamura, Hinata [Yokoyama Junior High School, Sanda, Hachioji, Tokyo 193-0832 (Japan); Passaquieti, Roberto [Dipartimento di Fisica ' Enrico Fermi' and INFN Sezione di Pisa, Universita' di Pisa, Largo Bruno Pontecorvo, I-56127 Pisa (Italy); DeSalvo, Riccardo [LIGO Observatories, California Institute of Technology, Pasadena, CA 91125 (United States)

2009-08-21

The concept of utilizing directional radiative cooling to correct the problem of thermal lensing in the mirrors of the LIGO/VIRGO gravitational wave detectors has been shown and has prospects for future use. Two different designs utilizing this concept, referred to as the baffled and parabolic mirror solutions, have been proposed with different means of controlling the cooling power. The technique takes advantage of the power naturally radiated by the mirror surfaces at room temperature to prevent their heating by the powerful stored laser beams. The baffled solution has been simulated via COMSOL Multiphysics as a design tool. Finally, the parabolic mirror concept was experimentally validated with the results falling in close agreement with theoretical cooling calculations. The technique of directional radiative thermal correction can be reversed to image heat rings on the mirrors periphery to remotely and dynamically correct their radius of curvature without subjecting the mirror to relevant perturbations.

Cooling load reduction by means of night sky radiation

International Nuclear Information System (INIS)

Kamaruddin Abdullah; Armansyah, H.T.; Dyah, W.; Gunadnya, I.B.P.

2006-01-01

Nocturnal cooling can work under clear sky condition of the humid tropical climate. Such effect had been observed in a cool storage facilities for potatoes and for temporary storage of fresh vegetables installed in highland area of Candi kuning village of Bali. Test results have shown that the rate of heat dissipation to the sky could reduce storage temperature to 15 o C had been achieved when the nocturnal cooling unit was combined with modified cooling tower and 1 kW cooling effect of an auxiliary cooling unit. Under such condition the facility could maintain better quality of stored vegetables, such as broccoli, shallot, and celery as compared to those stored in room without cooling facility. The estimated average cooling rate due to night sky radiation was 47.6 W/m 2 , on September 28, 1999 and 47.2 W/m 2 with the lowest water temperature of 14 o C under ambient temperature of 16 o C

Evaporative behavior of carbon with MPD Arc Jet

Energy Technology Data Exchange (ETDEWEB)

Sukegawa, Toshio; Madarame, Haruki; Okamoto, Koji [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

1996-10-01

Using the Magneto-Plasma-Dynamic Arc Jet (MPD Arc Jet) device, the plasma-material interaction during simulated plasma disruption was experimentally investigated. To clarify the effects of the evaporation, the isotropic graphite was used as a target. The thermal conductivity of the isotropic graphite was much higher than that of the pyrolytic graphite, resulting in smaller evaporation. The light intensity distribution during the simulated disruption for the isotropic graphite was quite different from that for the pyrolytic graphite. (author)

Monolayer graphene dispersion and radiative cooling for high power LED

Science.gov (United States)

Hsiao, Tun-Jen; Eyassu, Tsehaye; Henderson, Kimberly; Kim, Taesam; Lin, Chhiu-Tsu

2013-10-01

Molecular fan, a radiative cooling by thin film, has been developed and its application for compact electronic devices has been evaluated. The enhanced surface emissivity and heat dissipation efficiency of the molecular fan coating are shown to correlate with the quantization of lattice modes in active nanomaterials. The highly quantized G and 2D bands in graphene are achieved by our dispersion technique, and then incorporated in an organic-inorganic acrylate emulsion to form a coating assembly on heat sinks (for LED and CPU). This water-based dielectric layer coating has been formulated and applied on metal core printed circuit boards. The heat dissipation efficiency and breakdown voltage are evaluated by a temperature-monitoring system and a high-voltage breakdown tester. The molecular fan coating on heat dissipation units is able to decrease the equilibrium junction temperature by 29.1 ° C, while functioning as a dielectric layer with a high breakdown voltage (>5 kV). The heat dissipation performance of the molecular fan coating applied on LED devices shows that the coated 50 W LED gives an enhanced cooling of 20% at constant light brightness. The schematics of monolayer graphene dispersion, undispersed graphene platelet, and continuous graphene sheet are illustrated and discussed to explain the mechanisms of radiative cooling, radiative/non-radiative, and non-radiative heat re-accumulation.

Monolayer graphene dispersion and radiative cooling for high power LED

International Nuclear Information System (INIS)

Hsiao, Tun-Jen; Eyassu, Tsehaye; Henderson, Kimberly; Kim, Taesam; Lin, Chhiu-Tsu

2013-01-01

Molecular fan, a radiative cooling by thin film, has been developed and its application for compact electronic devices has been evaluated. The enhanced surface emissivity and heat dissipation efficiency of the molecular fan coating are shown to correlate with the quantization of lattice modes in active nanomaterials. The highly quantized G and 2D bands in graphene are achieved by our dispersion technique, and then incorporated in an organic-inorganic acrylate emulsion to form a coating assembly on heat sinks (for LED and CPU). This water-based dielectric layer coating has been formulated and applied on metal core printed circuit boards. The heat dissipation efficiency and breakdown voltage are evaluated by a temperature-monitoring system and a high-voltage breakdown tester. The molecular fan coating on heat dissipation units is able to decrease the equilibrium junction temperature by 29.1 ° C, while functioning as a dielectric layer with a high breakdown voltage (>5 kV). The heat dissipation performance of the molecular fan coating applied on LED devices shows that the coated 50 W LED gives an enhanced cooling of 20% at constant light brightness. The schematics of monolayer graphene dispersion, undispersed graphene platelet, and continuous graphene sheet are illustrated and discussed to explain the mechanisms of radiative cooling, radiative/non-radiative, and non-radiative heat re-accumulation. (paper)

Is the relationship between parental abuse and mobile phone dependency (MPD contingent across neighborhood characteristics? A multilevel analysis of Korean Children and Youth Panel Survey.

Directory of Open Access Journals (Sweden)

Harris Hyun-Soo Kim

Full Text Available Research indicates that mobile phone dependency (MPD is associated with various behavioral and internalizing problems. While a significant amount of findings points to its negative outcomes, there is a dearth of evidence concerning the determinants of MPD. This study focuses on this critical, yet understudied, subject by analyzing the associations between abusive parenting style, neighborhood characteristics, and MPD among youths in South Korea, a country with one of the highest mobile broadband penetration rates in the world. Based on the secondary analysis of two waves of Korean Children and Youth Panel Survey (KCYPS, a government-funded multiyear study, we investigate individual- and contextual-level factors underlying MPD. Findings show that, net of a host of time-lagged controls (including baseline dependency from the previous year, abusive parenting style significantly increases adolescent MPD. After adjusting for individual level characteristics, however, no contextual-level effect is found, i.e., residing in a neighborhood with a relatively higher proportion of parental abuse is not related to greater MPD. Finally, two cross-level interaction effects are observed. First, the association between parental abuse and MPD is weaker in a neighborhood context with better educated inhabitants (more college graduates. Second, it is reinforced in demographically "aged" communities with more elderly residents.

Is the relationship between parental abuse and mobile phone dependency (MPD) contingent across neighborhood characteristics? A multilevel analysis of Korean Children and Youth Panel Survey.

Science.gov (United States)

Kim, Harris Hyun-Soo; Chun, JongSerl

2018-01-01

Research indicates that mobile phone dependency (MPD) is associated with various behavioral and internalizing problems. While a significant amount of findings points to its negative outcomes, there is a dearth of evidence concerning the determinants of MPD. This study focuses on this critical, yet understudied, subject by analyzing the associations between abusive parenting style, neighborhood characteristics, and MPD among youths in South Korea, a country with one of the highest mobile broadband penetration rates in the world. Based on the secondary analysis of two waves of Korean Children and Youth Panel Survey (KCYPS), a government-funded multiyear study, we investigate individual- and contextual-level factors underlying MPD. Findings show that, net of a host of time-lagged controls (including baseline dependency from the previous year), abusive parenting style significantly increases adolescent MPD. After adjusting for individual level characteristics, however, no contextual-level effect is found, i.e., residing in a neighborhood with a relatively higher proportion of parental abuse is not related to greater MPD. Finally, two cross-level interaction effects are observed. First, the association between parental abuse and MPD is weaker in a neighborhood context with better educated inhabitants (more college graduates). Second, it is reinforced in demographically "aged" communities with more elderly residents.

A comparison of twice-weekly MPD-PUVA and three times-weekly skin typing-PUVA regimens for the treatment of psoriasis

Energy Technology Data Exchange (ETDEWEB)

Buckley, D.A.; Rogers, S. [City of Dublin Skin and Cancer Hospital, Dublin (Ireland); Healy, E. [Royal Victoria Infirmary, Newcastle upon Tyne (United Kingdom)

1995-09-01

The most frequent PUVA treatment regimen in current use is three times weekly, using skin typing to estimate the starting dose. Recently, it was suggested that twice-weekly treatment, using the minimal phototoxic dose- (MPD) to calculate suberythmal starting doses of UVA, achieved similar clearance rates with fewer treatments and a lower cumulative UVA dose. We have carried out a trial on 83 patients, comparing twice-weekly MPD-PUVA with three times-weekly skin typing-PUVA, in order to test this hypothesis. Although clearance rates were comparable between the two regimens, there was no overall significant difference in the number of treatments or in the cumulative UVA doses at clearance. However, for patients with skin types I and II the cumulative UVA dose was significantly higher using the twice-weekly MPD regimen (70.OJ/cm{sup 2} vs. 55.8J/cm{sup 2}; P<0.05). Our results do not confirm that there is a reduction in cumulative UVA dosage with twice-weekly MPD-PUVA. (Author).

Simulation Study of Discharging PCM Ceiling Panels through Night - time Radiative Cooling

DEFF Research Database (Denmark)

Bourdakis, Eleftherios; Kazanci, Ongun Berk; Grossule, F.

2016-01-01

demand. In the present simulation study, the coupling of nighttime radiative cooling with PCM for cooling an office room was investigated. For cooling water through nighttime radiative cooling two types of solar panels were utilized, an unglazed solar collector and photovoltaic/thermal (PV/T) panels...... provided by the PV/T panels was 43 W/m2 for Copenhagen, while for Milan and Athens it was 36 W/m2 and 34 W/m2, respectively. The cooling power of the unglazed solar collector was negligible. Finally, the total electricity produced in Copenhagen for the simulated period was 371 kWh, while for Milan...... and increase use of renewable energy sources. The aim is that by 2020 all new buildings should be nearly zero-energy buildings. A solution that could contribute to this is the combination of photovoltaic panels for the production of electricity and phase change material (PCM) for the reduction of peak cooling...

Helium-hydrogen microplasma device (MPD) on postage-stamp-size plastic-quartz chips.

Science.gov (United States)

Weagant, Scott; Karanassios, Vassili

2009-10-01

A new design of a miniaturized, atmospheric-pressure, low-power (e.g., battery-operated), self-igniting, planar-geometry microplasma device (MPD) for use with liquid microsamples is described. The inexpensive MPD was a hybrid, three-substrate quartz-plastic-plastic structure and it was formed on chips with area the size of a small postage stamp. The substrates were chosen for rapid prototyping and for speedy device-geometry testing and evaluation. The approximately 700-microm (diameter) and 7-mm (long) He-H(2) (3% H(2)) microplasma was formed by applying high-voltage ac between two needle electrodes. Operating conditions were found to be critical in sustaining stable microplasma on plastic substrates. Spectral interference from the electrode materials was not observed. A small-size, electrothermal vaporization system was used for introduction of microliter volumes of liquids into the MPD. The microplasma was operated from an inexpensive power supply. And, operation from a 14.4-V battery has been demonstrated. Microplasma background emission in the spectral range between 200 and 850 nm obtained using a portable, fiber-optic spectrometer is reported. Analyte emission from microliter volumes of dilute single-element standard solutions of Cd, Cu, K, Li, Mg, Mn, Na, Pb, and Zn is documented. Element-dependent precision was between 10-25% (the average was 15%) and detection limits ranged between 1.5 and 350 ng. The system was used for the determination of Na in diluted bottled-water samples.

Radiative human body cooling by nanoporous polyethylene textile.

Science.gov (United States)

Hsu, Po-Chun; Song, Alex Y; Catrysse, Peter B; Liu, Chong; Peng, Yucan; Xie, Jin; Fan, Shanhui; Cui, Yi

2016-09-02

Thermal management through personal heating and cooling is a strategy by which to expand indoor temperature setpoint range for large energy saving. We show that nanoporous polyethylene (nanoPE) is transparent to mid-infrared human body radiation but opaque to visible light because of the pore size distribution (50 to 1000 nanometers). We processed the material to develop a textile that promotes effective radiative cooling while still having sufficient air permeability, water-wicking rate, and mechanical strength for wearability. We developed a device to simulate skin temperature that shows temperatures 2.7° and 2.0°C lower when covered with nanoPE cloth and with processed nanoPE cloth, respectively, than when covered with cotton. Our processed nanoPE is an effective and scalable textile for personal thermal management. Copyright © 2016, American Association for the Advancement of Science.

Performance analysis on utilization of sky radiation cooling energy for space cooling. Part 2; Hosha reikyaku riyo reibo system ni kansuru kenkyu. 2

Energy Technology Data Exchange (ETDEWEB)

Marushima, S; Saito, T [Tohoku University, Sendai (Japan)

1996-10-27

Studies have been made about a heat accumulation tank type cooling system making use of radiation cooling that is a kind of natural energy. The daily operating cycle of the cooling system is described below. A heat pump air conditioner performs cooling during the daytime and the exhaust heat is stored in a latent heat accumulation tank; the heat is then used for the bath and tapwater in the evening; at night radiation cooling is utilized to remove the heat remnant in the tank for the solidification of the phase change material (PCM); the solidified PCM serves as the cold heat source for the heat pump air conditioner to perform cooling. The new system decelerates urban area warming because it emits the cooler-generated waste heat not into the atmosphere but into space taking advantage of radiation cooling. Again, the cooler-generated waste heat may be utilized for energy saving and power levelling. For the examination of nighttime radiation cooling characteristics, CaCl2-5H2O and Na2HPO4-12H2O were tested as the PCM. Water was used as the heating medium. In the case of a PCM high in latent heat capacity, some work has to be done for insuring sufficient heat exchange for it by, for instance, rendering the flow rate low. The coefficient of performance of the system discussed here is three times higher than that of the air-cooled type heat pump system. 8 refs., 5 figs., 4 tabs.

Observations of Infrared Radiative Cooling in the Thermosphere on Daily to Multiyear Timescales from the TIMED/SABER Instrument

Science.gov (United States)

Mlynczak, Martin G.; Hunt, Linda A.; Marshall, B. Thomas; Martin-Torres, F. Javier; Mertens, Christopher J.; Russell, James M., III; Remsberg, Ellis E.; Lopez-Puertas, Manuel; Picard, Richard; Winick, Jeremy;

Determination of the minimal phototoxic dose and colorimetry in psoralen plus ultraviolet A radiation therapy.

Science.gov (United States)

Kraemer, Cristine Kloeckner; Menegon, Dóris Baratz; Cestari, Tania Ferreira

2005-10-01

The use of an adequate initial dose of ultraviolet A (UVA) radiation for photochemotherapy is important to prevent burns secondary to overdosage, meanwhile avoiding a reduced clinical improvement and long-term risks secondary to underdosage. The ideal initial dose of UVA can be achieved based on the phototype and the minimal phototoxic dose (MPD). The objective measurement of constitutive skin color (colorimetry) is another method commonly used to quantify the erythematous skin reaction to ultraviolet radiation exposure. The aim of this study was to determine variations in MPD and constitutional skin color (coordinate L(*)) within different phototypes in order to establish the best initial dose of UVA radiation for photochemotherapy patients. Thirty-six patients with dermatological conditions and 13 healthy volunteers were divided into five groups according to phototype. Constitutional skin color of the infra-axillary area was assessed by colorimetry. The infra-axillary area was subsequently divided into twelve 1.5 cm(2) regions to determine the MPD; readings were performed 72 h after oral administration of 8-methoxypsoralen (MOP) followed by exposure of the demarcated regions to increasing doses of UVA. The majority of the participants were women (73.5%) and their mean age was 38.8 years. The MPD ranged from 4 to 12 J/cm(2) in phototypes II and III; from 10 to 18 J/cm(2) in type IV; from 12 to 24 J/cm(2) in type V and from 18 to 32 J/cm(2) in type VI. The analysis of colorimetric values (L(*) coordinate) and MPD values allowed the definition of three distinctive groups of individuals composed by phototypes II and III (group 1), types IV and V (group 2), and phototype VI (group 3). MPD and L(*) coordinate showed variation within the same phototype and superposition between adjacent phototypes. The values of the L(*) coordinate and the MPD lead to the definition of three distinct sensitivity groups: phototypes II and III, IV and V and type VI. Also, the MPD values

BM@N and MPD experiments at NICA

Directory of Open Access Journals (Sweden)

Kekelidze Vladimir

2018-01-01

Full Text Available The project NICA (Nuclotron-based Ion Collider fAcility aims to study hot and baryon rich QCD matter in heavy ion collisions in the energy range SNN = 4 − 11 GeV. The rich heavy-ion physics program will be performed at two experiments, BM@N (Baryonic Matter at Nuclotron at beams extracted from the Nuclotron, and at MPD (Multi-Purpose Detector at the NICA collider. This program covers a variety of phenomena in strongly interacting matter of the highest baryonic density, which includes study of collective effects, production of hyperon and hypernuclei, in-medium modification of meson properties, and event-by-event fluctuations.

Radiation safety standards

International Nuclear Information System (INIS)

1975-01-01

This is a basic document with which all rules and regulations, etc., concerning protection from ionizing radiations of workers and the general population have to conform. Basic concepts, dimensions, units, and terms used in the area of radiation safety are defined. Radiation exposures are sorted out into three categories: A, to personnel; B, to individual members of the popul;tion; and C, to the general population. Critical organs, furthermore, comprise four groups, the first of them being applicable to the whole-body gonads and bone marrow. Category A maximum permissible dose (MPD) to first group critical organs is 5 rem/year; to second group, 15 rem/year; to thrid group, 3O rem/year; and to fourth group, 75 rem/year. These rate figures include doses from both external and internal radiation exposure. Quality factors needed in computing doses from various types of radiation are provided. Permissible planned exposure levels are specified and guidelines given for accidental exposures. A radiation accident is considered to have occurred if the relevant critical organ dose is 5 times the annual MPD for that organ. For individual members of the population (category B), annual somatic doses to first group critical organs shall not exceed 0,5 rem. Population exposure is controlled in terms of genetically significant dose, which shall not exceed 5 rem/30 years. (G.G.)

The absorption and emission spectrum of radiative cooling galactic fountain gas

Science.gov (United States)

Benjamin, Robert A.; Shapiro, Paul R.

1993-01-01

We have calculated the time-dependent, nonequilibrium thermal and ionization history of gas cooling radiatively from 10(exp 6) K in a one-dimensional, planar, steady-state flow model of the galactic fountain, including the effects of radiative transfer. Our previous optically thin calculations explored the effects of photoionization on such a flow and demonstrated that self-ionization was sufficient to cause the flow to match the observed galactic halo column densities of C 4, Si 4, and N 5 and UV emission from C 4 and O 3 in the constant density (isochoric) limit, which corresponded to cooling regions homogeneous on scales D less than or approximately equal to 1 kpc. Our new calculations which take full account of radiative transfer confirm the importance of self-ionization in enabling such a flow to match the data but allow a much larger range for cooling region sizes, i.e. D(sub 0) greater than or approximately equal to 15 pc. For an initial flow velocity v(sub 0) approximately equal to 100 km/s, comparable to the sound speed of a 10(exp 6) K gas, the initial density is found to be n(sub h,0) is approximately 2 x 10(exp -2) cm(exp -3), in reasonable agreement with other observation estimates, and D(sub 0) is approximately equal to 40 pc. We also compare predicted H(alpha) fluxes, UV line emission, and broadband x-ray fluxes with observed values. One dimensional numerical hydrodynamical calculations including the effects of radiative cooling are also presented.

Benchmark Linelists and Radiative Cooling Functions for LiH Isotopologues

Science.gov (United States)

Diniz, Leonardo G.; Alijah, Alexander; Mohallem, José R.

2018-04-01

Linelists and radiative cooling functions in the local thermodynamic equilibrium limit have been computed for the six most important isotopologues of lithium hydride, 7LiH, 6LiH, 7LiD, 6LiD, 7LiT, and 6LiT. The data are based on the most accurate dipole moment and potential energy curves presently available, the latter including adiabatic and leading relativistic corrections. Distance-dependent reduced vibrational masses are used to account for non-adiabatic corrections of the rovibrational energy levels. Even for 7LiH, for which linelists have been reported previously, the present linelist is more accurate. Among all isotopologues, 7LiH and 6LiH are the best coolants, as shown by the radiative cooling functions.

An intelligent approach for cooling radiator fault diagnosis based on infrared thermal image processing technique

International Nuclear Information System (INIS)

Taheri-Garavand, Amin; Ahmadi, Hojjat; Omid, Mahmoud; Mohtasebi, Seyed Saeid; Mollazade, Kaveh; Russell Smith, Alan John; Carlomagno, Giovanni Maria

2015-01-01

This research presents a new intelligent fault diagnosis and condition monitoring system for classification of different conditions of cooling radiator using infrared thermal images. The system was adopted to classify six types of cooling radiator faults; radiator tubes blockage, radiator fins blockage, loose connection between fins and tubes, radiator door failure, coolant leakage, and normal conditions. The proposed system consists of several distinct procedures including thermal image acquisition, image pre-processing, image processing, two-dimensional discrete wavelet transform (2D-DWT), feature extraction, feature selection using a genetic algorithm (GA), and finally classification by artificial neural networks (ANNs). The 2D-DWT is implemented to decompose the thermal images. Subsequently, statistical texture features are extracted from the original images and are decomposed into thermal images. The significant selected features are used to enhance the performance of the designed ANN classifier for the 6 types of cooling radiator conditions (output layer) in the next stage. For the tested system, the input layer consisted of 16 neurons based on the feature selection operation. The best performance of ANN was obtained with a 16-6-6 topology. The classification results demonstrated that this system can be employed satisfactorily as an intelligent condition monitoring and fault diagnosis for a class of cooling radiator. - Highlights: • Intelligent fault diagnosis of cooling radiator using thermal image processing. • Thermal image processing in a multiscale representation structure by 2D-DWT. • Selection features based on a hybrid system that uses both GA and ANN. • Application of ANN as classifier. • Classification accuracy of fault detection up to 93.83%

Thermal performance of a radiatively cooled system for quantum optomechanical experiments in space

International Nuclear Information System (INIS)

Pilan Zanoni, André; Burkhardt, Johannes; Johann, Ulrich; Aspelmeyer, Markus; Kaltenbaek, Rainer; Hechenblaikner, Gerald

2016-01-01

Highlights: • We improved performance and design aspects of a radiatively cooled instrument. • A heat-flow analysis showed near optimal performance of the shield design. • A simple modification to imaging optics allowed further improvements. • We studied the thermal behavior for different orbital cases. • A transfer-function analysis showed strong attenuation of thermal variations. - Abstract: Passive cooling of scientific instruments via thermal radiation to deep space offers many advantages over active cooling in terms of mission cost, lifetime and the achievable quality of vacuum and microgravity. Motivated by the mission proposal MAQRO to test the foundations of quantum physics harnessing a deep-space environment, we investigate the performance of a radiatively cooled instrument, where the environment of a test particle in a quantum superposition has to be cooled to less than 20 K. We perform a heat-transfer analysis between the instrument components and a transfer-function analysis on thermal oscillations induced by the spacecraft interior and dissipative sources. The thermal behavior of the instrument is discussed for an orbit around a Lagrangian point and for a highly elliptical Earth orbit. Finally, we investigate possible design improvements. These include a mirror-based design of the imaging system on the optical bench (OB) and an extension of the heat shields.

Astrophysically relevant radiatively cooled hypersonic bow shocks in nested wire arrays

Science.gov (United States)

Ampleford, David

2009-11-01

We have performed laboratory experiments which introduce obstructions into hypersonic plasma flows to study the formation of shocks. Astrophysical observations have demonstrated many examples of equivalent radiatively cooled bow shocks, for example the head of protostellar jets or supernova remnants passing through the interstellar medium or between discrete clumps in jets. Wire array z-pinches allow us to study quasi-planar radiatively cooled flows in the laboratory. The early stage of a wire array z-pinch implosion consists of a steady flow of the wire material towards the axis. Given a high rate of radiative cooling, these flows reach high sonic- Mach numbers, typically up to 5. The 2D nature of this configuration allows the insertion of obstacles into the flow, such as a concentric ``inner'' wire array, as has previously been studied for ICF research. Here we study the application of such a nested array to laboratory astrophysics where the inner wires act as obstructions perpendicular to the flow, and induce bow shocks. By varying the wire array material (W/Al), the significance of radiative cooling on these shocks can be controlled, and is shown to change the shock opening angle. As multiple obstructions are present, the experiments show the interaction of multiple bow shocks. It is also possible to introduce a magnetic field around the static object, increasing the opening angle of the shocks. Further experiments can be designed to control the flow density, magnetic field structure and obstruction locations. In collaboration with: S.V. Lebedev, M.E. Cuneo, C.A. Jennings, S.N. Bland, J.P. Chittenden, A. Ciardi, G.N. Hall, S.C. Bott, M. Sherlock, A. Frank, E. Blackman

Radiative cooling for storage of vegetables in the tropics

Energy Technology Data Exchange (ETDEWEB)

Kamaruddin, A; Wilujeng, T; Mahendra, M S

2000-07-01

Radiative cooling in combination with packed bed cooling tower may be applicable in establishing low cost and environmentally friendly pre-cooling and temporary storage facility in vegetable growing areas in Indonesia. To test the possibility of such a system, an experiment using a prototype storage system had been conducted in Candikuning village in Bali, Indonesia. From this test it was recorded that the attainable storage temperature was between 18 and 22{sup o}C. Under this environment tomatoes and potatoes, packed with stretch film could be stored respectively, for 16 days with weight loss of 1.7% and for 21 days with weight loss of 0.4%. After 4 days of storage, broccoli with 4 hours precooling, the recorded minimum weight loss was 4.9%. (author)

Internal Roof and Attic Thermal Radiation Control Retrofit Strategies for Cooling-Dominated Climates

Energy Technology Data Exchange (ETDEWEB)

Fallahi, A. [Fraunhofer Center for Sustainable Energy Systems, Boston, MA (United States); Duraschlag, H. [Fraunhofer Center for Sustainable Energy Systems, Boston, MA (United States); Elliott, D. [Fraunhofer Center for Sustainable Energy Systems, Boston, MA (United States); Hartsough, J. [Fraunhofer Center for Sustainable Energy Systems, Boston, MA (United States); Shukla, N. [Fraunhofer Center for Sustainable Energy Systems, Boston, MA (United States); Kosny, J. [Fraunhofer Center for Sustainable Energy Systems, Boston, MA (United States)

2013-12-01

This project evaluates the cooling energy savings and cost effectiveness of radiation control retrofit strategies for residential attics in U.S. cooling-dominated climates. Usually, in residential applications, radiation control retrofit strategies are applied below the roof deck or on top of the attic floor insulation. They offer an alternative option to the addition of conventional bulk insulation such as fiberglass or cellulose insulation. Radiation control is a potentially low-cost energy efficiency retrofit strategy that does not require significant changes to existing homes. In this project, two groups of low-cost radiation control strategies were evaluated for southern U.S. applications. One uses a radiant barrier composed of two aluminum foils combined with an enclosed reflective air space and the second uses spray-applied interior radiation control coatings (IRCC).

Internal Roof and Attic Thermal Radiation Control Retrofit Strategies for Cooling-Dominated Climates

Energy Technology Data Exchange (ETDEWEB)

Fallahi, A. [Fraunhofer Center for Sustainable Energy Systems (CSE), Boston, MA (United States); Durschlag, H. [Fraunhofer Center for Sustainable Energy Systems (CSE), Boston, MA (United States); Elliott, D. [Fraunhofer Center for Sustainable Energy Systems (CSE), Boston, MA (United States); Hartsough, J. [Fraunhofer Center for Sustainable Energy Systems (CSE), Boston, MA (United States); Shukla, N. [Fraunhofer Center for Sustainable Energy Systems (CSE), Boston, MA (United States); Kosny, J. [Fraunhofer Center for Sustainable Energy Systems (CSE), Boston, MA (United States)

2013-12-01

This project evaluates the cooling energy savings and cost effectiveness of radiation control retrofit strategies for residential attics in U.S. cooling-dominated climates. Usually, in residential applications, radiation control retrofit strategies are applied below the roof deck or on top of the attic floor insulation. They offer an alternative option to the addition of conventional bulkinsulation such as fiberglass or cellulose insulation. Radiation control is a potentially low-cost energy efficiency retrofit strategy that does not require significant changes to existing homes. In this project, two groups of low-cost radiation control strategies were evaluated for southern U.S. applications. One uses a radiant barrier composed of two aluminum foils combined with an enclosedreflective air space and the second uses spray-applied interior radiation control coatings (IRCC).

Effect of solar radiation on the performance of cross flow wet cooling tower in hot climate of Iran

Science.gov (United States)

Banooni, Salem; Chitsazan, Ali

2016-11-01

In some cities such as Ahvaz-Iran, the solar radiation is very high and the annual-mean-daily of the global solar radiation is about 17.33 MJ m2 d-1. Solar radiation as an external heat source seems to affect the thermal performance of the cooling towers. Usually, in modeling cooling tower, the effects of solar radiation are ignored. To investigate the effect of sunshade on the performance and modeling of the cooling tower, the experiments were conducted in two different states, cooling towers with and without sunshade. In this study, the Merkel's approach and finite difference technique are used to predict the thermal behavior of cross flow wet cooling tower without sunshade and the results are compared with the data obtained from the cooling towers with and without sunshade. Results showed that the sunshade is very efficient and it reduced the outlet water temperature, the approach and the water exergy of the cooling tower up to 1.2 °C, 15 and 1.1 %, respectively and increased the range and the efficiency of the cooling tower up to 29 and 37 %, respectively. Also, the sunshade decreased the error between the experimental data of the cooling tower with sunshade and the modeling results of the cooling tower without sunshade 1.85 % in average.

The Multi-Purpose Detector (MPD) of the collider experiment

Energy Technology Data Exchange (ETDEWEB)

Golovatyuk, V.; Kekelidze, V.; Kolesnikov, V.; Rogachevsky, O. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Sorin, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation); National Research Nuclear University (MEPhI), Moscow (Russian Federation)

2016-08-15

The project NICA (Nuclotron-based Ion Collider fAcility) is aimed to study dense baryonic matter in heavy-ion collisions in the energy range up to √(s{sub NN}) = 11 GeV with average luminosity of L = 10{sup 27} cm{sup -2}s{sup -1} (for {sup 197}Au{sup 79}). The experimental program at the NICA collider will be performed with the Multi-Purpose Detector (MPD). We report on the main physics objectives of the NICA heavy-ion program and present the main detector components. (orig.)

Night time cooling by ventilation or night sky radiation combined with in-room radiant cooling panels including phase change materials

DEFF Research Database (Denmark)

Bourdakis, Eleftherios; Olesen, Bjarne W.; Grossule, Fabio

Night sky radiative cooling technology using PhotoVoltaic/Thermal panels (PVT) and night time ventilation have been studied both by means of simulations and experiments to evaluate their potential and to validate the created simulation model used to describe it. An experimental setup has been...... depending on the sky clearness. This cooling power was enough to remove the stored heat and regenerate the ceiling panels. The validation simulation model results related to PCM were close to the corresponding results extracted from the experiment, while the results related to the production of cold water...... through the night sky radiative cooling differed significantly. The possibility of night time ventilation was studied through simulations for three different latitudes. It was concluded that for Danish climatic conditions night time ventilation would also be able to regenerate the panels while its...

Passive radiative cooling of a HTS coil for attitude orbit control in micro-spacecraft

Science.gov (United States)

Inamori, Takaya; Ozaki, Naoya; Saisutjarit, Phongsatorn; Ohsaki, Hiroyuki

2015-02-01

This paper proposes a novel radiative cooling system for a high temperature superconducting (HTS) coil for an attitude orbit control system in nano- and micro-spacecraft missions. These days, nano-spacecraft (1-10 kg) and micro-spacecraft (10-100 kg) provide space access to a broader range of spacecraft developers and attract interest as space development applications. In planetary and high earth orbits, most previous standard-size spacecraft used thrusters for their attitude and orbit control, which are not available for nano- and micro-spacecraft missions because of the strict power consumption, space, and weight constraints. This paper considers orbit and attitude control methods that use a superconducting coil, which interacts with on-orbit space plasmas and creates a propulsion force. Because these spacecraft cannot use an active cooling system for the superconducting coil because of their mass and power consumption constraints, this paper proposes the utilization of a passive radiative cooling system, in which the superconducting coil is thermally connected to the 3 K cosmic background radiation of deep space, insulated from the heat generation using magnetic holders, and shielded from the sun. With this proposed cooling system, the HTS coil is cooled to 60 K in interplanetary orbits. Because the system does not use refrigerators for its cooling system, the spacecraft can achieve an HTS coil with low power consumption, small mass, and low cost.

Three Canted Radiator Panels to Provide Adequate Cooling for Instruments on Slewing Spacecraft in LEO

Science.gov (United States)

Choi, Michael K.

2012-01-01

Certain free-flying spacecraft in low Earth orbit (LEO) or payloads on the International Space Station (ISS) are required to slew to point the telescopes at targets. Instrument detectors and electronics require cooling. Traditionally a planar thermal radiator is used. The temperature of such a radiator varies significantly when the spacecraft slews because its view factors to space vary significantly. Also for payloads on the ISS, solar impingement on the radiator is possible. These thermal adversities could lead to inadequate cooling for the instrument. This paper presents a novel thermal design concept that utilizes three canted radiator panels to mitigate this problem. It increases the overall radiator view factor to cold space and reduces the overall solar or albedo flux absorbed per unit area of the radiator.

Measurement of the radiative cooling rates for high-ionization species of krypton using an electron beam ion trap

International Nuclear Information System (INIS)

Radtke, R.; Biedermann, C.; Fuchs, T.; Fussmann, G.; Beiersdorfer, P.

2000-01-01

We describe a measurement of the radiative cooling rate for krypton made at the Berlin electron beam ion trap (EBIT). The EBIT was tuned to a charge-state distribution approaching the ionization balance of a plasma at a temperature of about 5 keV. To determine the cooling rate, we made use of EBIT's capabilities to sample a wide range of electron-beam energies and distinguish between different radiation channels. We have measured the x-ray emission from bremsstrahlung, radiative recombination, dielectronic recombination, and line radiation following electron-impact excitation. The dominant contribution to the cooling rate is made by the n=3-2, n=4-2,... x rays of the L-shell spectra of krypton, which produce more than 75% of the total radiation loss. A difference with theoretical calculations is noted for the measured total cooling rate. The predicted values are lower by a factor of 1.5-2, depending on the theoretical model. For our measurement of the cooling rate, we estimate an uncertainty interval of 22-30 %. (c) 2000 The American Physical Society

Evaluation of Electromagnetic Forces in an Axially-Magnetized MPD Arcjet Plasma

International Nuclear Information System (INIS)

Tobari, Hiroyuki; Yoshino, Kyohei; Hattori, Kunihiko; Ando, Akira; Inutake, Masaaki

2003-01-01

Characteristics of an axially-magnetized plasma flow has been investigated in the vicinity of a magneto-plasma-dynamic arcjet (MPDA) by use of spectroscopy, Mach probes and magnetic probes. Axial and rotational flow velocity and temperature of He ion and atom near the muzzle region of MPDA are measured by Doppler shift and broadening of the HeI (λ = 578.56 nm) and HeII (λ = 468.58 nm) lines. It has been observed that the plasma rotates with a rigid body and that ion temperature increases extraordinarily in a factor of 2-3 at several cm downstream from MPD outlet when a discharge current increases with a lower mass-flow-rate of He gas. Therefore, the ion acoustic Mach number saturates at near unity. To clarify mechanisms of ion heating and electromagnetic acceleration, spatial distribution of induced magnetic fields are measured in the vicinity of MPD outlet by magnetic probes. Spatial structure of magnetic field and plasma current density is clarified experimentally in the muzzle region of MPDA. Among three components of jxB force F, radial component Fr is dominant and axial component Fz is much smaller than Fr because of a generation of a drag force canceling an acceleration force

Evidence for Solar Cycle Influence on the Infrared Energy Budget and Radiative Cooling of the Thermosphere

Science.gov (United States)

Mlynczak, Martin G.; Martin-Torres, F. Javier; Marshall, B. Thomas; Thompson, R. Earl; Williams, Joshua; Turpin, TImothy; Kratz, D. P.; Russell, James M.; Woods, Tom; Gordley, Larry L.

2007-01-01

We present direct observational evidence for solar cycle influence on the infrared energy budget and radiative cooling of the thermosphere. By analyzing nearly five years of data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, we show that the annual mean infrared power radiated by the nitric oxide (NO) molecule at 5.3 m has decreased by a factor of 2.9. This decrease is correlated (r = 0.96) with the decrease in the annual mean F10.7 solar index. Despite the sharp decrease in radiated power (which is equivalent to a decrease in the vertical integrated radiative cooling rate), the variability of the power as given in the standard deviation of the annual means remains approximately constant. A simple relationship is shown to exist between the infrared power radiated by NO and the F10.7 index, thus providing a fundamental relationship between solar activity and the thermospheric cooling rate for use in thermospheric models. The change in NO radiated power is also consistent with changes in absorbed ultraviolet radiation over the same time period.

Cooling systems and hybrid A/C systems using an electromagnetic radiation-absorbing complex

Science.gov (United States)

Halas, Nancy J.; Nordlander, Peter; Neumann, Oara

2015-05-19

A method for powering a cooling unit. The method including applying electromagnetic (EM) radiation to a complex, where the complex absorbs the EM radiation to generate heat, transforming, using the heat generated by the complex, a fluid to vapor, and sending the vapor from the vessel to a turbine coupled to a generator by a shaft, where the vapor causes the turbine to rotate, which turns the shaft and causes the generator to generate the electric power, wherein the electric powers supplements the power needed to power the cooling unit

Quantum limits of photothermal and radiation pressure cooling of a movable mirror

International Nuclear Information System (INIS)

Pinard, M; Dantan, A

2008-01-01

We present a general quantum-mechanical theory for the cooling of a movable mirror in an optical cavity when both radiation pressure self-cooling and photothermal cooling effects are present, and show that these two mechanisms may bring the oscillator close to its quantum ground state, although in quite different regimes. Self-cooling caused by coherent exchange of excitations between the cavity mode and the mirror vibrational mode is shown to dominate in the good-cavity regime-when the mechanical resonance frequency is larger than the cavity decay rate, whereas photothermal-induced cooling can be made predominant in the bad-cavity limit. Both situations are compared, and the relevant physical quantities to be optimized in order to reach the lowest final excitation number states are extracted.

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

The Role of Cerenkov Radiation in the Pressure Balance of Cool Core Clusters of Galaxies

Energy Technology Data Exchange (ETDEWEB)

Lieu, Richard [Department of Physics, University of Alabama, Huntsville, AL 35899 (United States)

2017-03-20

Despite the substantial progress made recently in understanding the role of AGN feedback and associated non-thermal effects, the precise mechanism that prevents the core of some clusters of galaxies from collapsing catastrophically by radiative cooling remains unidentified. In this Letter, we demonstrate that the evolution of a cluster's cooling core, in terms of its density, temperature, and magnetic field strength, inevitably enables the plasma electrons there to quickly become Cerenkov loss dominated, with emission at the radio frequency of ≲350 Hz, and with a rate considerably exceeding free–free continuum and line emission. However, the same does not apply to the plasmas at the cluster's outskirts, which lacks such radiation. Owing to its low frequency, the radiation cannot escape, but because over the relevant scale size of a Cerenkov wavelength the energy of an electron in the gas cannot follow the Boltzmann distribution to the requisite precision to ensure reabsorption always occurs faster than stimulated emission, the emitting gas cools before it reheats. This leaves behind the radiation itself, trapped by the overlying reflective plasma, yet providing enough pressure to maintain quasi-hydrostatic equilibrium. The mass condensation then happens by Rayleigh–Taylor instability, at a rate determined by the outermost radius where Cerenkov radiation can occur. In this way, it is possible to estimate the rate at ≈2 M {sub ⊙} year{sup −1}, consistent with observational inference. Thus, the process appears to provide a natural solution to the longstanding problem of “cooling flow” in clusters; at least it offers another line of defense against cooling and collapse should gas heating by AGN feedback be inadequate in some clusters.

Recent developments in track reconstruction and hadron identification at MPD

Science.gov (United States)

Mudrokh, A.; Zinchenko, A.

2017-03-01

A Monte Carlo simulation of real detector effects with as many details as possible has been carried out instead of a simplified Geant point smearing approach during the study of the detector performance. Some results of realistic simulation of the MPD TPC (Time Projection Chamber) including digitization in central Au+Au collisions have been obtained. Particle identification (PID) has been tuned to account for modifications in the track reconstruction. Some results on hadron identification in the TPC and TOF (Time Of Flight) detectors with realistically simulated response have been also obtained.

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

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...

Radiative cooling test facility and performance evaluation of 4-MIL aluminized polyvinyl fluoride and white-paint surfaces

Energy Technology Data Exchange (ETDEWEB)

Kruskopf, M.S.; Berdahl, P.; Martin, M.; Sakkal, F.; Sobolewski, M.

1980-11-01

A test facility designed to measure the amount of radiative cooling a specific material or assembly of materials will produce when exposed to the sky is described. Emphasis is placed upon assemblies which are specifically designed to produce radiative cooling and which therefore offer promise for the reduction of temperatures and/or humidities in occupied spaces. The hardware and software used to operate the facility are documented and the results of the first comprehensive experiments are presented. A microcomputer-based control/data acquisition system was employed to study the performance of two prototype radiator surfaces: 4-mil aluminized polyvinyl fluoride (PVF) and white painted surfaces set below polyethylene windscreens. The cooling rates for materials tested were determined and can be approximated by an equation (given). A computer model developed to simulate the cooling process is presented. (MCW)

A model for radiative cooling of a semitransparent molten glass jet

International Nuclear Information System (INIS)

Song, M.; Ball, K.S.; Bergman, T.L.

1998-01-01

Transfer of molten glass from location to location typically involves a pouring process, during which a stream of glass is driven by gravity and cooled by combined convective and radiative heat transfer. This study of the thermal and fluid mechanics aspects of glass pouring is motivated by the glass casting of vitrified, surplus weapons-grade plutonium. Here, a mathematical model for the radiative cooling of a semitransparent molten glass jet with temperature-dependent viscosity has been developed and is implemented numerically. The axial velocity and jet diameter variations along the length of the jet, the axial bulk mean temperature distributions, and the centerline-to-surface glass temperature distributions are determined for different processing conditions. Comparisons are also made between the semitransparent predictions, which are based on a spectral discrete ordinates model, and predictions for an opaque medium

Beam test results of STS prototype modules for the future accelerator experiments FAIR/CBM and NICA/MPD projects

Science.gov (United States)

Kharlamov, Petr; Dementev, Dmitrii; Shitenkov, Mikhail

2017-10-01

High-energy heavy-ion collision experiments provide the unique possibility to create and investigate extreme states of strongly-interacted matter and address the fundamental aspects of QCD. The experimental investigation the QCD phase diagram would be a major breakthrough in our understanding of the properties of nuclear matter. The reconstruction of the charged particles created in the nuclear collisions, including the determination of their momenta, is the central detection task in high-energy heavy-ion experiments. It is taken up by the Silicon Tracking System in CBM@FAIR and by Inner Tracker in MPD@NICA currently under development. These experiments requires very fast and radiation hard detectors, a novel data read-out and analysis concept including free streaming front-end electronics. Thermal and beam tests of prototype detector modules for these tracking systems showed the stability of sensors and readout electronics operation.

Reduction of vibration forces transmitted from a radiator cooling fan to a vehicle body

Science.gov (United States)

Lim, Jonghyuk; Sim, Woojeong; Yun, Seen; Lee, Dongkon; Chung, Jintai

2018-04-01

This article presents methods for reducing transmitted vibration forces caused by mass unbalance of the radiator cooling fan during vehicle idling. To identify the effects of mass unbalance upon the vibration characteristics, vibration signals of the fan blades were experimentally measured both with and without an added mass. For analyzing the vibration forces transmitted to the vehicle body, a dynamic simulation model was established that reflected the vibration characteristics of the actual system. This process included a method described herein for calculating the equivalent stiffness and the equivalent damping of the shroud stators and rubber mountings. The dynamic simulation model was verified by comparing its results with experimental results of the radiator cooling fan. The dynamic simulation model was used to analyze the transmitted vibration forces at the rubber mountings. Also, a measure was established to evaluate the effects of varying the design parameters upon the transmitted vibration forces. We present design guidelines based on these analyses to reduce the transmitted vibration forces of the radiator cooling fan.

Probing polymer crystallization at processing-relevant cooling rates with synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Cavallo, Dario, E-mail: Dario.cavallo@unige.it [University of Genoa, Dept. of Chemistry and Industrial Chemistry, Via Dodecaneso 31, 16146 Genoa (Italy); Portale, Giuseppe [ESRF, Dubble CRG, Netherlands Organization of Scientific Research (NWO), 38043 Grenoble (France); Androsch, René [Martin-Luther-University Halle-Wittenberg, Center of Engineering Sciences, D-06099 Halle/S. (Germany)

2015-12-17

Processing of polymeric materials to produce any kind of goods, from films to complex objects, involves application of flow fields on the polymer melt, accompanied or followed by its rapid cooling. Typically, polymers solidify at cooling rates which span over a wide range, from a few to hundreds of °C/s. A novel method to probe polymer crystallization at processing-relevant cooling rates is proposed. Using a custom-built quenching device, thin polymer films are ballistically cooled from the melt at rates between approximately 10 and 200 °C/s. Thanks to highly brilliant synchrotron radiation and to state-of-the-art X-ray detectors, the crystallization process is followed in real-time, recording about 20 wide angle X-ray diffraction patterns per second while monitoring the instantaneous sample temperature. The method is applied to a series of industrially relevant polymers, such as isotactic polypropylene, its copolymers and virgin and nucleated polyamide-6. Their crystallization behaviour during rapid cooling is discussed, with particular attention to the occurrence of polymorphism, which deeply impact material’s properties.

Improved lumped models for transient combined convective and radiative cooling of multi-layer composite slabs

International Nuclear Information System (INIS)

An Chen; Su Jian

2011-01-01

Improved lumped parameter models were developed for the transient heat conduction in multi-layer composite slabs subjected to combined convective and radiative cooling. The improved lumped models were obtained through two-point Hermite approximations for integrals. Transient combined convective and radiative cooling of three-layer composite slabs was analyzed to illustrate the applicability of the proposed lumped models, with respect to different values of the Biot numbers, the radiation-conduction parameter, the dimensionless thermal contact resistances, the dimensionless thickness, and the dimensionless thermal conductivity. It was shown by comparison with numerical solution of the original distributed parameter model that the higher order lumped model (H 1,1 /H 0,0 approximation) yielded significant improvement of average temperature prediction over the classical lumped model. In addition, the higher order (H 1,1 /H 0,0 ) model was applied to analyze the transient heat conduction problem of steel-concrete-steel sandwich plates. - Highlights: → Improved lumped models for convective-radiative cooling of multi-layer slabs were developed. → Two-point Hermite approximations for integrals were employed. → Significant improvement over classical lumped model was achieved. → The model can be applied to high Biot number and high radiation-conduction parameter. → Transient heat conduction in steel-concrete-steel sandwich pipes was analyzed as an example.

Nighttime radiative cooling potential of unglazed and PV/T solar collectors: parametric and experimental analyses

DEFF Research Database (Denmark)

Pean, Thibault Quentin; Gennari, Luca; Olesen, Bjarne W.

2015-01-01

Nighttime radiative cooling technology has been studied both by means of simulations and experiments, to evaluate its potential and to validate the existing theoretical models used to describe it. Photovoltaic/thermal panels (PV/T) and unglazed solar collectors have been chosen as case studies....... The obtained values showed a good agreement with the ones found in the literature about solar panels or other kinds of heat sinks used for radiative cooling applications. The panels provided a cooling performance per night ranging between 0.2 and 0.9 kWh/m2 of panel. The COP values (defined as the ratio....... An experimental setup has been constructed and tested during summer of 2014, at the Technical University of Denmark. The cooling performance (heat loss) has been measured simultaneously for both types of panels, installed side-by-side. The experimental results have been compared with the results from a commercial...

Experimental study of discharging PCM ceiling panels through nocturnal radiative cooling

DEFF Research Database (Denmark)

Bourdakis, Eleftherios; Péan, Thibault Q.; Gennari, Luca

PhotoVoltaic/Thermal (PV/T) panels were used for cooling water through the principle of nocturnal radiative cooling. This water was utilised for discharging Phase Change Material (PCM) which was embedded in ceiling panels in a climate chamber. Three different sets of flow rates were examined...... for the solar and the PCM loops, for five days each. The highest examined water flow rate (210 l/h) in the PCM loop provided the best thermal environment in the climate chamber, namely 92% of the occupancy time was within the range of Category III of Standard EN 15251. Although the lowest examined water flow...... rate (96 l/h) in the solar loop provided the highest average cooling power, due to the significant variations in the weather conditions during the three experimental cases, made it impossible to determine to which extent the difference in the cooling power is due to the different water flow rate...

Performative building envelope design correlated to solar radiation and cooling energy consumption

Science.gov (United States)

Jacky, Thiodore; Santoni

2017-11-01

Climate change as an ongoing anthropogenic environmental challenge is predominantly caused by an amplification in the amount of greenhouse gases (GHGs), notably carbon dioxide (CO2) in building sector. Global CO2 emissions are emitted from HVAC (Heating, Ventilation, and Air Conditioning) occupation to provide thermal comfort in building. In fact, the amount of energy used for cooling or heating building is implication of building envelope design. Building envelope acts as interface layer of heat transfer between outdoor environment and the interior of a building. It appears as wall, window, roof and external shading device. This paper examines performance of various design strategy on building envelope to limit solar radiation and reduce cooling loads in tropical climate. The design strategies are considering orientation, window to wall ratio, material properties, and external shading device. This research applied simulation method using Autodesk Ecotect to investigate simultaneously between variations of wall and window ratio, shading device composition and the implication to the amount of solar radiation, cooling energy consumption. Comparative analysis on the data will determine logical variation between opening and shading device composition and cooling energy consumption. Optimizing the building envelope design is crucial strategy for reducing CO2 emissions and long-term energy reduction in building sector. Simulation technology as feedback loop will lead to better performative building envelope.

Passive cryogenic cooling of electrooptics with a heat pipe/radiator.

Science.gov (United States)

Nelson, B E; Goldstein, G A

1974-09-01

The current status of the heat pipe is discussed with particular emphasis on applications to cryogenic thermal control. The competitive nature of the passive heat pipe/radiator system is demonstrated through a comparative study with other candidate systems for a 1-yr mission. The mission involves cooling a spaceborne experiment to 100 K while it dissipates 10 W.

Development of radiative-cooling materials. Final technical report: FY 1980-1981

Energy Technology Data Exchange (ETDEWEB)

1981-01-01

Work on research and development on glazing and selective emitter materials that will enhance day and night sky radiative cooling is described. The emphasis is on glazing development with a secondary interest in the appropriate selective emitter. The testing focused on the individual material properties. (MHR)

Mock Data Challenge for the MPD/NICA Experiment on the HybriLIT Cluster

Science.gov (United States)

Gertsenberger, Konstantin; Rogachevsky, Oleg

2018-02-01

Simulation of data processing before receiving first experimental data is an important issue in high-energy physics experiments. This article presents the current Event Data Model and the Mock Data Challenge for the MPD experiment at the NICA accelerator complex which uses ongoing simulation studies to exercise in a stress-testing the distributed computing infrastructure and experiment software in the full production environment from simulated data through the physical analysis.

Readout system of TPC/MPD NICA project

Energy Technology Data Exchange (ETDEWEB)

Averyanov, A. V.; Bajajin, A. G.; Chepurnov, V. F.; Cheremukhina, G. A.; Fateev, O. V.; Korotkova, A. M.; Levchanovskiy, F. V.; Lukstins, J.; Movchan, S. A.; Razin, S. V.; Rybakov, A. A.; Vereschagin, S. V., E-mail: vereschagin@jinr.ru; Zanevsky, Yu. V.; Zaporozhets, S. A.; Zruyev, V. N. [Joint Institute for Nuclear Research (Russian Federation)

2015-12-15

The time-projection chamber (TPC) is the main tracking detector in the MPD/NICA. The information on charge-particle tracks in the TPC is registered by the MWPG with cathode pad readout. The frontend electronics (FEE) are developed with use of modern technologies such as application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), and data transfer to a concentrator via a fast optical interface. The main parameters of the FEE are as follows: total number of channels, ∼95 000; data stream from the whole TPC, 5 GB/s; low power consumption, less than 100 mW/ch; signal to noise ratio (S/N), 30; equivalent noise charge (ENC), <1000e{sup –} (C{sub in} = 10–20 pF); and zero suppression (pad signal rejection ∼90%). The article presents the status of the readout chamber construction and the data acquisition system. The results of testing FEE prototypes are presented.

Beam test results of STS prototype modules for the future accelerator experiments FAIR/CBM and NICA/MPD projects

Directory of Open Access Journals (Sweden)

Kharlamov Petr

2017-01-01

Full Text Available High-energy heavy-ion collision experiments provide the unique possibility to create and investigate extreme states of strongly-interacted matter and address the fundamental aspects of QCD. The experimental investigation the QCD phase diagram would be a major breakthrough in our understanding of the properties of nuclear matter. The reconstruction of the charged particles created in the nuclear collisions, including the determination of their momenta, is the central detection task in high-energy heavy-ion experiments. It is taken up by the Silicon Tracking System in CBM@FAIR and by Inner Tracker in MPD@NICA currently under development. These experiments requires very fast and radiation hard detectors, a novel data read-out and analysis concept including free streaming front-end electronics. Thermal and beam tests of prototype detector modules for these tracking systems showed the stability of sensors and readout electronics operation.

Successful application of MPD (managed pressure drilling) for prevention, control, and detection of borehole ballooning in tight gas reservoir in Cuervito Field, Mexico

Energy Technology Data Exchange (ETDEWEB)

Ochoa, A.; Acevedo, O.; Nieto, L. [Petrobras (United States); Lambarria, J.E. [PEMEX Exploration and Production (Mexico); Perez, H. [Weatherford (United States)

2011-07-01

The Cuervito field is an oil play located in the Burgos Basin in northeastern Mexico. In order to reach the highest yielding sands, wells in the Cuervito field are usually set up with 3 casings. However, the ballooning effect, an elastoplastic behavior of a well's walls, occurs during drilling operations, leading to loss of circulation. Two methods, based on geological and geopressure data, were found to minimize this effect: either putting in an extra casing, or using an unconventional drilling technique. As the managed pressure drilling (MPD) technique is less complex and more elegant, a pilot project was implemented using this method on a well. Results showed that MPD minimized lost time and enhanced drilling efficiency. This paper demonstrated that the use of MPD in the Cuervito field is a good solution for identifying and controlling the ballooning effect and this technique was successfully applied to the next 3 wells drilled subsequently.

On physical and numerical instabilities arising in simulations of non-stationary radiatively cooling shocks

Science.gov (United States)

Badjin, D. A.; Glazyrin, S. I.; Manukovskiy, K. V.; Blinnikov, S. I.

2016-06-01

We describe our modelling of the radiatively cooling shocks and their thin shells with various numerical tools in different physical and calculational setups. We inspect structure of the dense shell, its formation and evolution, pointing out physical and numerical factors that sustain its shape and also may lead to instabilities. We have found that under certain physical conditions, the circular shaped shells show a strong bending instability and successive fragmentation on Cartesian grids soon after their formation, while remain almost unperturbed when simulated on polar meshes. We explain this by physical Rayleigh-Taylor-like instabilities triggered by corrugation of the dense shell surfaces by numerical noise. Conditions for these instabilities follow from both the shell structure itself and from episodes of transient acceleration during re-establishing of dynamical pressure balance after sudden radiative cooling onset. They are also easily excited by physical perturbations of the ambient medium. The widely mentioned non-linear thin shell instability, in contrast, in tests with physical perturbations is shown to have only limited chances to develop in real radiative shocks, as it seems to require a special spatial arrangement of fluctuations to be excited efficiently. The described phenomena also set new requirements on further simulations of the radiatively cooling shocks in order to be physically correct and free of numerical artefacts.

Radiation-resistance of polyurethane pipes for cooling liquid in BES III

International Nuclear Information System (INIS)

Li Xunfeng; Zheng Lifang; Ji Quan; Wu Ping; Wang Li

2009-01-01

Gamma ray radiation and neutron radiation are predominant in the working conditions of BES III, and the radiation-resistance aging of polyurethane pipes is very important in this condition, as the pipes of cooling liquid for beam pipe and SCQ (superconducting quadrupole) vacuum pipe in BESIII. Polyester polyurethane pipes and polyether polyurethane pipes were irradiated by gamma ray and neutron. The radiation doses were as much as ten years' doses in BES. Pressure test, FTIR and thermal analysis were used to study the radiation-resistance of these two kinds of polyurethane pipes. The results show that the radiation-resistance and thermal stability of polyester polyurethane pipes are prior to those of polyether polyurethane pipes, and the pressure resistance of polyester polyurethane pipes is almost maintained after the irradiation by gamma ray and neutron, but the polyether polyurethane pipes can be aged and ruptured after the irradiation by neutron. (authors)

Parallel LC circuit model for multi-band absorption and preliminary design of radiative cooling.

Science.gov (United States)

Feng, Rui; Qiu, Jun; Liu, Linhua; Ding, Weiqiang; Chen, Lixue

2014-12-15

We perform a comprehensive analysis of multi-band absorption by exciting magnetic polaritons in the infrared region. According to the independent properties of the magnetic polaritons, we propose a parallel inductance and capacitance(PLC) circuit model to explain and predict the multi-band resonant absorption peaks, which is fully validated by using the multi-sized structure with identical dielectric spacing layer and the multilayer structure with the same strip width. More importantly, we present the application of the PLC circuit model to preliminarily design a radiative cooling structure realized by merging several close peaks together. This omnidirectional and polarization insensitive structure is a good candidate for radiative cooling application.

Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody

Science.gov (United States)

Zhu, Linxiao; Raman, Aaswath P.; Fan, Shanhui

2015-01-01

A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13 °C due to radiative cooling. Our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities. PMID:26392542

Solar radiation and cooling load calculation for radiant systems: Definition and evaluation of the Direct Solar Load

DEFF Research Database (Denmark)

Causone, Francesco; Corgnati, Stefano P.; Filippi, Marco

2010-01-01

The study of the influence of solar radiation on the built environment is a basic issue in building physics and currently it is extremely important because glazed envelopes are widely used in contemporary architecture. In the present study, the removal of solar heat gains by radiant cooling systems...... is investigated. Particular attention is given to the portion of solar radiation converted to cooling load, without taking part in thermal absorption phenomena due to the thermal mass of the room. This specific component of the cooling load is defined as the Direct Solar Load. A simplified procedure to correctly...... calculate the magnitude of the Direct Solar Load in cooling load calculations is proposed and it is implemented with the Heat Balance method and the Radiant Time Series method. The F ratio of the solar heat gains directly converted to cooling load, in the case of a low thermal mass radiant ceiling...

Radiation shield analysis for a manned Mars rover

International Nuclear Information System (INIS)

Morley, N.J.; ElGenk, M.S.

1991-01-01

Radiation shielding for unmanned space missions has been extensively studied; however, designs of man-rated shields are minimal. Engle et al.'s analysis of a man-rated, multilayered shield composed of two and three cycles (a cycle consists of a tungsten and a lithium hydride layer) is the basis for the work reported in this paper. The authors present the results of a recent study of shield designs for a manned Mars rover powered by a 500-kW(thermal) nuclear reactor. A train-type rover vehicle was developed, which consists of four cars and is powered by an SP-100-type nuclear reactor heat source. The maximum permissible dose rate (MPD) from all sources is given by the National Council on Radiation Protection and Measurements as 500 mSv/yr (50 rem/yr) A 3-yr Mars mission (2-yr round trip and 1-yr stay) will deliver a 1-Sv natural radiation dose without a solar particle event, 450 mSv/yr in flight, and an additional 100 mSv on the planet surface. An anomalously large solar particle event could increase the natural radiation dose for unshielded astronauts on the Martian surface to 200 mSv. This limits the MPD to crew members from the nuclear reactor to 300 mSv

Numerical simulation of heat transfer process in solar enhanced natural draft dry cooling tower with radiation model

International Nuclear Information System (INIS)

Wang, Qiuhuan; Zhu, Jialing; Lu, Xinli

2017-01-01

Graphical abstract: A 3-D numerical model integrated with a discrete ordinate (DO) solar radiation model (considering solar radiation effect in the room of solar collector) was developed to investigate the influence of solar radiation intensity and ambient pressure on the efficiency and thermal characteristics of the SENDDCT. Our study shows that introducing such a radiation model can more accurately simulate the heat transfer process in the SENDDCT. Calculation results indicate that previous simulations overestimated solar energy obtained by the solar collector and underestimated the heat loss. The cooling performance is improved when the solar radiation intensity or ambient pressure is high. Air temperature and velocity increase with the increase of solar radiation intensity. But ambient pressure has inverse effects on the changes of air temperature and velocity. Under a condition that the solar load increases but the ambient pressure decreases, the increased rate of heat transferred in the heat exchanger is not obvious. Thus the performance of the SENDDCT not only depends on the solar radiation intensity but also depends on the ambient pressure. - Highlights: • A radiation model has been introduced to accurately simulate heat transfer process. • Heat transfer rate would be overestimated if the radiation model was not introduced. • The heat transfer rate is approximately proportional to solar radiation intensity. • The higher the solar radiation or ambient pressure, the better SENDDCT performance. - Abstract: Solar enhanced natural draft dry cooling tower (SENDDCT) is more efficient than natural draft dry cooling tower by utilizing solar radiation in arid region. A three-dimensional numerical model considering solar radiation effect was developed to investigate the influence of solar radiation intensity and ambient pressure on the efficiency and thermal characteristics of SENDDCT. The numerical simulation outcomes reveal that a model with consideration of

Calculations of combined radiation and convection heat transfer in rod bundles under emergency cooling conditions

International Nuclear Information System (INIS)

Sun, K.H.; Gonzalez-Santalo, J.M.; Tien, C.L.

1976-01-01

A model has been developed to calculate the heat transfer coefficients from the fuel rods to the steam-droplet mixture typical of Boiling Water Reactors under Emergency Core Cooling System (ECCS) operation conditions during a postulated loss-of-coolant accident. The model includes the heat transfer by convection to the vapor, the radiation from the surfaces to both the water droplets and the vapor, and the effects of droplet evaporation. The combined convection and radiation heat transfer coefficient can be evaluated with respect to the characteristic droplet size. Calculations of the heat transfer coefficient based on the droplet sizes obtained from the existing literature are consistent with those determined empirically from the Full-Length-Emergency-Cooling-Heat-Transfer (FLECHT) program. The present model can also be used to assess the effects of geometrical distortions (or deviations from nominal dimensions) on the heat transfer to the cooling medium in a rod bundle

The cooling of particle beams

International Nuclear Information System (INIS)

Sessler, A.M.

1994-10-01

A review is given of the various methods which can be employed for cooling particle beams. These methods include radiation damping, stimulated radiation damping, ionization cooling, stochastic cooling, electron cooling, laser cooling, and laser cooling with beam coupling. Laser Cooling has provided beams of the lowest temperatures, namely 1 mK, but only for ions and only for the longitudinal temperature. Recent theoretical work has suggested how laser cooling, with the coupling of beam motion, can be used to reduce the ion beam temperature in all three directions. The majority of this paper is devoted to describing laser cooling and laser cooling with beam coupling

Radiation Heat Transfer Effect on Thermal Sizing of Air-Cooling Heat Exchanger of Emergency Cooldown Tank

Energy Technology Data Exchange (ETDEWEB)

Moon, Joo Hyung; Kim, Young In; Kim, Keung Koo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, Myoung Jun; Lee, Hee Joon [School of Mechanical Eng., Kookmin University, Seoul (Korea, Republic of)

2014-10-15

An attempt has begun to extend the life time of emergency cooldown tank (ECT) by Korea Atomic Energy Research Institute (KAERI) researchers. Moon et al. recently reported a basic concept upon how to keep the ECT in operation beyond 72 hours after an accident occurs without any active corrective actions for the postulated design basis accidents. When the SMART (System-integrated Modular Advanced Reac-Tor) received its Standard Design Approval (SDA) for the first time in the world, hybrid safety systems are applied. However, the passive safety systems of SMART are being enforced in response to the public concern for much safer reactors since the Fukushima accident occurred. The ECT is a major component of a passive residual heat removal system (PRHRS), which is one of the most important systems to enhance the safety of SMART. It is being developed in a SMART safety enhancement project to contain enough cooling water to remove a sensible heat and a decay heat from reactor core for 72 hours since an accident occurs. Moon et al. offered to install another heat exchanger above the ECT and to recirculate an evaporated steam into water, which enables the ECT to be in operation, theoretically, indefinitely. An investigation was made to determine how long and how many tubes were required to meet the purpose of the study. In their calculation, however, a radiation heat transfer effect was neglected. The present study is to consider the radiation heat transfer for the design of air-cooling heat exchanger. Radiation heat transfer is normally ignored in many situations, but this is not the case for the present study. Kim et al. conducted thermal sizing of scaled-down ECT heat exchanger, which will be used to validate experimentally the basic concept of the present study. Their calculation is also examined to see if a radiation heat transfer effect was taken into consideration. The thermal sizing of an air-cooling heat exchanger was conducted including radiation heat transfer

A new boundary control scheme for simultaneous achievement of H-mode and radiative cooling (SHC boundary)

International Nuclear Information System (INIS)

Ohyabu, N.

1995-05-01

We have proposed a new boundary control scheme (SHC boundary), which could allow simultaneous achievement of the H-mode type confinement improvement and radiative cooling with wide heat flux distribution. In our proposed configuration, a low m island layer sharply separates a plasma confining region from an open 'ergodic' boundary. The degree of openness in the ergodic boundary must be high enough to make the plasma pressure constant along the field line, which in turn separates low density plasma just outside the plasma confining region (the key external condition for achieving a good H-mode discharge) from very high density, cold radiative plasma near the wall (required for effective edge radiative cooling). Examples of such proposed SHC boundaries for Heliotron typed devices and tokamaks are presented. (author)

Empirical evaluation of the radiative cooling coefficient for krypton gas in the FTU plasma

International Nuclear Information System (INIS)

Fournier, K.B.; Pacella, D.; Mazzitelli, G.; Stutman, D.; Soukanovskii, V.; Goldstein, W.H.

1997-01-01

For future fusion reactors, a careful balance must be achieved between the cooling of the outer plasma via impurity radiation and the deleterious effects of inevitable core penetration by impurity ions. We have injected krypton gas into the Frascati Tokamak Upgrade (FTU) plasma. The measured visible bremsstrahlung and bolometric signals from krypton have been inverted and the resulting radial impurity density profile and power loss profile for krypton gas are extracted. Using the measured electron density and temperature profiles, the radiative cooling coefficient for krypton is derived. The level of intrinsic impurities (Mo, Cr, Mn and Fe) in the plasma during the krypton puffing is monitored with a VUV SPRED spectrometer. Models for krypton emissivity from the literature are compared to our measured results. 7 figs

Pregnant x-ray technologist: providing adequate radiation safety for the fetus

International Nuclear Information System (INIS)

Caprio, M.L. Jr.

1980-01-01

The human embryo-fetus is highly radiosensitive and must be protected from excessive exposure to ionizing radiation. The maximum permissible dose equivalent for the developing embryo-fetus is set at 0.5 rem per year - the MPD level for members of the general public. Methods by which supervisory personnel can limit the fetal dose incurred by the occupational exposure of the mother are presented. It is recommended that supervisory personnel attempt to limit occupational exposure to the current non-occupational MPD levels for all x-ray technologists, thereby, insuring that the fetal dose limits are not surpassed and providing an added safety factor for personnel by keeping exposures as low as reasonably achievable

Thermal radiation characteristics and direct evidence of tungsten cooling on the way to nanostructure formation on its surface

Energy Technology Data Exchange (ETDEWEB)

Takamura, S., E-mail: takamura@aitech.ac.jp [Faculty of Engineering, Aichi Institute of Technology, Yakusa-cho, Toyota 470-0392 (Japan); Miyamoto, T. [Faculty of Engineering, Aichi Institute of Technology, Yakusa-cho, Toyota 470-0392 (Japan); Ohno, N. [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

2013-07-15

The physical properties of tungsten with nanostructure on its surface are investigated focusing on the thermal radiation and cooling characteristics. First, direct evidence of substantial W surface cooling has been clearly shown with use of a very thin thermocouple inserted into W target, which solves an uncertainty associated with a radiation thermometer. Second, the above measurements of W surface temperature make it possible to estimate quantitatively the total emissivity from which we may evaluate the radiative power through the Stefan–Boltzmann equation, which is very important for mitigation evaluation of a serious plasma heat load to the plasma-facing component.

Thermal radiation characteristics and direct evidence of tungsten cooling on the way to nanostructure formation on its surface

International Nuclear Information System (INIS)

Takamura, S.; Miyamoto, T.; Ohno, N.

2013-01-01

The physical properties of tungsten with nanostructure on its surface are investigated focusing on the thermal radiation and cooling characteristics. First, direct evidence of substantial W surface cooling has been clearly shown with use of a very thin thermocouple inserted into W target, which solves an uncertainty associated with a radiation thermometer. Second, the above measurements of W surface temperature make it possible to estimate quantitatively the total emissivity from which we may evaluate the radiative power through the Stefan–Boltzmann equation, which is very important for mitigation evaluation of a serious plasma heat load to the plasma-facing component

Radiation cooling and gain calculation for C VI 182 A line in C/Se plasma

International Nuclear Information System (INIS)

Nam, C.H.; Valeo, E.; Suckewer, S.; Feldman, U.

1986-04-01

A model is developed which is capable of describing the evolution of gain resulting from both rapid radiative and expansion cooling of a recombining, freely expanding plasma. It is demonstrated for the particular case of a carbon/selenium plasma that the cooling rate which leads to optimal gain can be achieved by adjusting the admixture of an efficiently radiating material (selenium) in the gain medium (carbon). Comparison is made to a recent observation of gain in a recent NRL/Rochester experiment with carbon/selenium plasma for the n = 3 → 2 transition in C VI occurring at 182 A. The predicted maximum gain is approx.10 cm -1 , as compared to observation of 2 to 3 cm -1

Electromechanically cooled germanium radiation detector system

International Nuclear Information System (INIS)

Lavietes, Anthony D.; Joseph Mauger, G.; Anderson, Eric H.

1999-01-01

We have successfully developed and fielded an electromechanically cooled germanium radiation detector (EMC-HPGe) at Lawrence Livermore National Laboratory (LLNL). This detector system was designed to provide optimum energy resolution, long lifetime, and extremely reliable operation for unattended and portable applications. For most analytical applications, high purity germanium (HPGe) detectors are the standard detectors of choice, providing an unsurpassed combination of high energy resolution performance and exceptional detection efficiency. Logistical difficulties associated with providing the required liquid nitrogen (LN) for cooling is the primary reason that these systems are found mainly in laboratories. The EMC-HPGe detector system described in this paper successfully provides HPGe detector performance in a portable instrument that allows for isotopic analysis in the field. It incorporates a unique active vibration control system that allows the use of a Sunpower Stirling cycle cryocooler unit without significant spectral degradation from microphonics. All standard isotopic analysis codes, including MGA and MGA++, GAMANL, GRPANL and MGAU, typically used with HPGe detectors can be used with this system with excellent results. Several national and international Safeguards organisations including the International Atomic Energy Agency (IAEA) and U.S. Department of Energy (DOE) have expressed interest in this system. The detector was combined with custom software and demonstrated as a rapid Field Radiometric Identification System (FRIS) for the U.S. Customs Service . The European Communities' Safeguards Directorate (EURATOM) is field-testing the first Safeguards prototype in their applications. The EMC-HPGe detector system design, recent applications, and results will be highlighted

Thermoregulated Nitric Cryosystem for Cooling Gas-Filled Detectors of Ionizing Radiation

Directory of Open Access Journals (Sweden)

Zharkov I.P.

2015-09-01

Full Text Available Cryosystem for cooling and filling of gas-filled detectors of ionizing radiation with compressed inert gas on the basis of wide-nitrogen cryostat, which provides detetector temperature control in a range of 173 — 293 K and its stabilization with accuracy of ± 1°. The work was carried out within the Ukraine — NATO Program of Collaboration, Grant SfP #984655.

Improved lumped models for transient combined convective and radiative cooling of a two-layer spherical fuel element

International Nuclear Information System (INIS)

Silva, Alice Cunha da; Su, Jian

2013-01-01

The High Temperature Gas cooled Reactor (HTGR) is a fourth generation thermal nuclear reactor, graphite-moderated and helium cooled. The HTGRs have important characteristics making essential the study of these reactors, as well as its fuel element. Examples of these are: high thermal efficiency,low operating costs and construction, passive safety attributes that allow implication of the respective plants. The Pebble Bed Modular Reactor (PBMR) is a HTGR with spherical fuel elements that named the reactor. This fuel element is composed by a particulate region with spherical inclusions, the fuel UO2 particles, dispersed in a graphite matrix and a convective heat transfer by Helium happens on the outer surface of the fuel element. In this work, the transient heat conduction in a spherical fuel element of a pebble-bed high temperature reactor was studied in a transient situation of combined convective and radiative cooling. Improved lumped parameter model was developed for the transient heat conduction in the two-layer composite sphere subjected to combined convective and radiative cooling. The improved lumped model was obtained through two-point Hermite approximations for integrals. Transient combined convective and radiative cooling of the two-layer spherical fuel element was analyzed to illustrate the applicability of the proposed lumped model, with respect to die rent values of the Biot number, the radiation-conduction parameter, the dimensionless thermal contact resistance, the dimensionless inner diameter and coating thickness, and the dimensionless thermal conductivity. It was shown by comparison with numerical solution of the original distributed parameter model that the improved lumped model, with H2,1/H1,1/H0,0 approximation yielded significant improvement of average temperature prediction over the classical lumped model. (author)

Comparative growth analysis of cool- and warm-season grasses in a cool-temperate environment

International Nuclear Information System (INIS)

Belesky, D.P.; Fedders, J.M.

1995-01-01

Using both cool-season (C3) and warm-season (C4) species is a viable means of optimizing herbage productivity over varying climatic conditions in temperate environments. Despite well-documented differences in water, N, and radiation use, no consistent evidence demonstrates productivity differences among C3 and C4 perennial grass species under identical management. A field study was conducted to determine relative growth rates (RGR), nitrogen productivity (NP), and mean radiation productivity (RP) (dry matter production as a function of incident radiation) of cool- and warm-season grasses managed identically. Results were used to identify management practices thd could lead to optimal productivity in combinations or mixtures of cool- and warm-season grasses. Dry matter yields of warm-season grasses equaled or surpassed those of cool-season grasses, despite a 40% shorter growth interval. Certain cool- and warm-season grasses appear to be suitable for use in mixtures, based on distribution of herbage production; however, actual compatibility may be altered by defoliation management. Relative growth rates varied among years and were about 40% lower for canopies clipped to a 10-cm residue height each time 20-cm of growth accumulated compared with other treatments. The RGR of warm-season grasses was twice that of cool-season grasses Nitrogen productivity (g DM g-1 N d -1) and mean radiation productivity (g DM MJ-1) for warm-season grasses was also more than twice that of cool-season grasses. Radiation productivity of cool-season grasses was dependent on N, while this was not always the case for warm-season grasses. The superior production capability of certain warm-season compared with cool-season grasses in a cool-temperate environment can be sustained under a range of defoliation treatments and demonstrates suitability for use in frequently defoliated situations

Investigation of thermal and hydrodynamic processes in the oil transformer radiator cooling system

OpenAIRE

Ільїн, Сергій Віталійович

2013-01-01

Despite the large number of publications in the field of transformer, heat transfer and hydrodynamic processes that take place in the radiator cooling systems, lack of attention. However, for a comprehensive analysis of the entire oil circuit in the transformer, it is necessary to take into account the work of the radiator, as it was on the efficiency of removal of heat in it will depend on the oil temperature at the inlet of the transformer. To achieve these objectives, this paper describes ...

EFFECT OF A RADIATION COOLING AND HEATING FUNCTION ON STANDING LONGITUDINAL OSCILLATIONS IN CORONAL LOOPS

Energy Technology Data Exchange (ETDEWEB)

Kumar, S.; Nakariakov, V. M.; Moon, Y.-J., E-mail: sanjaykumar@khu.ac.kr [School of Space Research, Kyung Hee University, Yongin, 446-701, Gyeonggi (Korea, Republic of)

2016-06-10

Standing long-period (with periods longer than several minutes) oscillations in large, hot (with a temperature higher than 3 MK) coronal loops have been observed as the quasi-periodic modulation of the EUV and microwave intensity emission and the Doppler shift of coronal emission lines, and they have been interpreted as standing slow magnetoacoustic (longitudinal) oscillations. Quasi-periodic pulsations of shorter periods, detected in thermal and non-thermal emissions in solar flares could be produced by a similar mechanism. We present theoretical modeling of the standing slow magnetoacoustic mode, showing that this mode of oscillation is highly sensitive to peculiarities of the radiative cooling and heating function. We generalized the theoretical model of standing slow magnetoacoustic oscillations in a hot plasma, including the effects of the radiative losses and accounting for plasma heating. The heating mechanism is not specified and taken empirically to compensate the cooling by radiation and thermal conduction. It is shown that the evolution of the oscillations is described by a generalized Burgers equation. The numerical solution of an initial value problem for the evolutionary equation demonstrates that different dependences of the radiative cooling and plasma heating on the temperature lead to different regimes of the oscillations, including growing, quasi-stationary, and rapidly decaying. Our findings provide a theoretical foundation for probing the coronal heating function and may explain the observations of decayless long-period, quasi-periodic pulsations in flares. The hydrodynamic approach employed in this study should be considered with caution in the modeling of non-thermal emission associated with flares, because it misses potentially important non-hydrodynamic effects.

Radiative losses and electron cooling rates for carbon and oxygen plasma impurities

International Nuclear Information System (INIS)

Marchand, R.; Bonnin, X.

1992-01-01

Radiative losses and electron cooling rates are calculated for carbon and oxygen ions under conditions relevant to fusion plasmas. Both rates are calculated with the most recent recommended atomic data. A modified coronal model which includes the effects of metastable states is described and used to calculate the rates. Comparisons with other approaches are also discussed. (author). 36 ref, figs

Parametrization of the average ionization and radiative cooling rates of carbon plasmas in a wide range of density and temperature

OpenAIRE

Gil de la Fe, Juan Miguel; Rodriguez Perez, Rafael; Florido, Ricardo; Garcia Rubiano, Jesus; Mendoza, M.A.; Nuez, A. de la; Espinosa, G.; Martel Escobar, Carlos; Mínguez Torres, Emilio

2013-01-01

In this work we present an analysis of the influence of the thermodynamic regime on the monochromatic emissivity, the radiative power loss and the radiative cooling rate for optically thin carbon plasmas over a wide range of electron temperature and density assuming steady state situations. Furthermore, we propose analytical expressions depending on the electron density and temperature for the average ionization and cooling rate based on polynomial fittings which are valid for the whole range...

A comparative study of the effects of Ag{sub 2}S films prepared by MPD and HRTD methods on the performance of polymer solar cells

Energy Technology Data Exchange (ETDEWEB)

Zhai, Yong; Li, Fumin; Ling, Lanyun [Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng, 475004 (China); School of Physics and Electronics, Henan University, Kaifeng, 475004 (China); Chen, Chong, E-mail: chongchen@henu.edu.cn [Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng, 475004 (China); School of Physics and Electronics, Henan University, Kaifeng, 475004 (China)

2016-10-30

Highlights: • Ag{sub 2}S nanocrystals are directly synthesized on ITO substrate by MPD and HRTD methods. • The Ag{sub 2}S films prepared by HRTD method have lower roughness and better uniformity. • The solar cells with the Ag{sub 2}S (HRTD, n) films show better device performance. - Abstract: In this work, the Ag{sub 2}S nanocrystalline thin films are deposited on ITO glass via molecular precursor decomposition (MPD) method and newly developed HRTD method for organic solar cells (ITO/Ag{sub 2}S/P3HT:PCBM/MoO{sub 3}/Au) as an electron selective layer and a light absorption material. The surface morphology, structure characterization, and optical property of the Ag{sub 2}S films prepared by these two methods were compared and the effect of the prepared Ag{sub 2}S film on the device performance is investigated. It is found that the Ag{sub 2}S films prepared by HRTD method have lower roughness and better uniformity than the corresponding films prepared by the MPD method. In addition, a more effective and rapid transporting ability for the electrons and holes in the ITO/Ag{sub 2}S(HRTD, n)/P3HT:PCBM/MoO{sub 3}/Au cells is found, which reduces the charge recombination, and thus, improves the device performance. The highest efficiency of 3.21% achieved for the ITO/Ag{sub 2}S(HRTD, 50)/P3HT:PCBM/MoO{sub 3}/Au cell is 93% higher than that of the ITO/Ag{sub 2}S(MPD, 2)/P3HT:PCBM/MoO{sub 3}/Au cell.

Protracted radiation-induced alterations in hematopoietic repair and recovery

International Nuclear Information System (INIS)

Seed, T.M.; Fritz, T.E.

1997-01-01

Pathologic predisposition of beagle dogs under chronic, low daily dose (7.5 cGy day -1 ) whole-body gamma irradiation has been studied relative to molecular repair and hematopoietic competency. Molecular repair, assessed by a microscopy-based unscheduled DNA synthesis (UDS) response, was measured within proliferative and nonproliferative marrow myeloid elements of dogs with markedly different hematopoietic capacities (low capacity, aplasia-prone [AA + ] versus high capacity, myeloproliferative disease-prone [MPD + ]) under protracted radiation stress. Results indicated that protracted exposure elicited a net increase in UDS-repair capacity that was largely independent of exposure duration. This enhanced capacity resulted from the increased strength of the UDS signal together with an expanded number of positively responding cells. The combined response was strong in primitive blasts and weak in more differentiated myelocytic cells. The UDS repair response of the MPD + dogs was significantly greater than that of the AA + animals and was clearly modified relative to the controls. These results suggest that both resiliency and pathologic potential of the hematopoietic system under protracted radiation stress is, in part, associated with an augmentable DNA repair within the more primitive myeloid marrow elements. (author)

Onderzoeksrapportage duurzaam koelen : EOS Renewable Cooling

NARCIS (Netherlands)

Broeze, J.; Sluis, van der S.; Wissink, E.

2010-01-01

For reducing energy use for cooling, alternative methods (that do not rely on electricity) are needed. Renewable cooling is based on naturally available resources such as evaporative cooling, free cooling, phase change materials, ground subcooling, solar cooling, wind cooling, night radiation &

Radiation abuse and its effects

Energy Technology Data Exchange (ETDEWEB)

Halm, A

1976-06-01

This paper delves into overuse practiced in diagnostic radiography. The conventional attitudes to low-dose irradiation are critically examined, as is the MPD related to individual radiosensitivity. Concern is expressed that a sizeable proportion of radiologists ignore important aspects of the Code of Practice and this attitude is readily emulated in the hospital setting. The author advocates education within the medical profession and the community on the risks involved in radiation abuse and the benefits derived from justified exposures to x rays.

Radiation abuse and its effects

International Nuclear Information System (INIS)

Halm, A.

1976-01-01

This paper delves into overuse practiced in diagnostic radiography. The conventional attitudes to low-dose irradiation are critically examined, as is the MPD related to individual radiosensitivity. Concern is expressed that a sizeable proportion of radiologists ignore important aspects of the Code of Practice and this attitude is readily emulated in the hospital setting. The author advocates education within the medical profession and the community on the risks involved in radiation abuse and the benefits derived from justified exposures to x rays. (author)

Homogenization of some radiative heat transfer models: application to gas-cooled reactor cores

International Nuclear Information System (INIS)

El Ganaoui, K.

2006-09-01

In the context of homogenization theory we treat some heat transfer problems involving unusual (according to the homogenization) boundary conditions. These problems are defined in a solid periodic perforated domain where two scales (macroscopic and microscopic) are to be taken into account and describe heat transfer by conduction in the solid and by radiation on the wall of each hole. Two kinds of radiation are considered: radiation in an infinite medium (non-linear problem) and radiation in cavity with grey-diffuse walls (non-linear and non-local problem). The derived homogenized models are conduction problems with an effective conductivity which depend on the considered radiation. Thus we introduce a framework (homogenization and validation) based on mathematical justification using the two-scale convergence method and numerical validation by simulations using the computer code CAST3M. This study, performed for gas cooled reactors cores, can be extended to other perforated domains involving the considered heat transfer phenomena. (author)

Time-dependent Cooling in Photoionized Plasma

Energy Technology Data Exchange (ETDEWEB)

Gnat, Orly, E-mail: orlyg@phys.huji.ac.il [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)

2017-02-01

I explore the thermal evolution and ionization states in gas cooling from an initially hot state in the presence of external photoionizing radiation. I compute the equilibrium and nonequilibrium cooling efficiencies, heating rates, and ion fractions for low-density gas cooling while exposed to the ionizing metagalactic background radiation at various redshifts ( z = 0 − 3), for a range of temperatures (10{sup 8}–10{sup 4} K), densities (10{sup −7}–10{sup 3} cm{sup −3}), and metallicities (10{sup −3}–2 times solar). The results indicate the existence of a threshold ionization parameter, above which the cooling efficiencies are very close to those in photoionization equilibrium (so that departures from equilibrium may be neglected), and below which the cooling efficiencies resemble those in collisional time-dependent gas cooling with no external radiation (and are thus independent of density).

Feasibility study on novel hybrid ground coupled heat pump system with nocturnal cooling radiator for cooling load dominated buildings

International Nuclear Information System (INIS)

Man, Yi; Yang, Hongxing; Spitler, Jeffrey D.; Fang, Zhaohong

2011-01-01

Highlights: → Propose a novel HGCHP system with NCR works as supplemental heat rejecter. → Establish the analytical model and computer program of NCR and novel HGCHP system to simulate their operation performance. → Design the novel HGCHP system for a sample building located in Hong Kong. → It is found to be feasible to use NCR serves as supplemental heat rejecter of the novel HGCHP system. → The novel HGCHP system provides a new valuable choice for air conditioning in cooling load dominated buildings. -- Abstract: When the ground coupled heat pump (GCHP) system is utilized for air conditioning in cooling load dominated buildings, the heat rejected into ground will accumulate around the ground heat exchangers (GHE) and results in system performance degradation. A novel hybrid ground coupled heat pump (HGCHP) system with nocturnal cooling radiator (NCR) works as supplemental heat rejecter is proposed in this paper to resolve this problem. The practical analytical model of NCR and novel HGCHP system are established. The computer program based on established model is developed to simulate the system operation performance. The novel HGCHP system is designed and simulated for a sample building located in Hong Kong, and a simple life cycle cost comparisons are carried out between this system and conventional GCHP system. The results indicate that it is feasible to use NCR serves as supplemental heat rejecter of the novel HGCHP system for cooling load dominated buildings even those located in humid subtropical climate areas. This novel HGCHP system provides a new valuable choice for air conditioning in cooling load dominated buildings, and it is especially suitable for buildings with limited surface land areas.

Design and analysis of the DII-D radiative divertor water-cooled structures

International Nuclear Information System (INIS)

Hollerbach, M.A.; Smith, J.P.; Baxi, C.B.; Bozek; Chin, E.; Phelps, R.D.; Redler, K.M.; Reis, E.E.

1995-10-01

The Radiative Divertor is a major modification to the divertor of DIII-D and is being designed and fabricated for installation in late 1996. The Radiative Divertor Program (RDP) will enhance the dissipative processes in the edge and divertor plasmas to reduce the heat flux and plasma erosion at the divertor target. This approach will have major implications for the heat removal methods used in future devices. The divertor is of slot-type configuration designed to minimize the flow of sputtered and injected impurities back to the core plasma. The new divertor will be composed of toroidally continuous, Inconel 625 water-cooled rings of sandwich construction with an internal water channel, incorporating seam welding to provide the water-to-vacuum seal as well as structural integrity. The divertor structure is designed to withstand electromagnetic loads as a result of halo currents and induced toroidal currents. It also accommodates the thermal differences experienced during the 400 degrees C bake used on DIII-D. A low Z plasma-facing surface is provided by mechanically attached graphite tiles. Water flow through the rings will inertially cool these tiles which will be subjected to 38 MW, 10 second pulses. Current schedules call for detailed design in 1996 with installation completed in March 1997. A full size prototype, one-quarter of one ring, is being built to validate manufacturing techniques, machining, roll-forming, and seam welding. The experience and knowledge gained through the fabrication of the prototype is discussed. The design of the electrically isolated (5 kV) vacuum-to-air water feedthroughs supplying the water-cooled rings is also discussed

Design and analysis of the DIII-D radiative divertor water-cooled structures

International Nuclear Information System (INIS)

Hollerbach, M.A.; Smith, J.P.; Baxi, C.B.; Bozek, A.S.; Chin, E.; Phelps, R.D.; Redler, K.M.; Reis, E.E.

1995-01-01

The Radiative Divertor is a major modification to the divertor of DIII-D and is being designed and fabricated for installation in late 1996. The Radiative Divertor Program (RDP) will enhance the dissipative processes in the edge and divertor plasmas to reduce the heat flux and plasma erosion at the divertor target. This approach will have major implications for the heat removal methods used in future devices. The divertor is of slot-type configuration designed to minimize the flow of sputtered and injected impurities back to the core plasma. The new divertor will be composed of toroidally continuous, Inconel 625 water-cooled rings of sandwich construction with an internal water channel, incorporating seam welding to provide the water-to-vacuum seal as well as structural integrity. The divertor structure is designed to withstand electro-magnetic loads as a result of halo currents and induced toroidal currents. It also accommodates the thermal differences experienced during the 400 C bake used on DIII-D. A low Z plasma-facing surface is provided by mechanically attached graphite tiles. Water flow through the rings will inertially cool these tiles which will be subjected to 38 MW, 10 second pulses. Current schedules call for detailed design in 1996 with installation completed in March 1997. A full size prototype, one-quarter of one ring, is being built to validate manufacturing techniques, machining, roll-forming, and seam welding. The experience and knowledge gained through the fabrication of the prototype is discussed. The design of the electrically isolated (5 kV) vacuum-to-air water feedthroughs supplying the water-cooled rings is also discussed

Divertor cooling device

International Nuclear Information System (INIS)

Nakayama, Tadakazu; Hayashi, Katsumi; Handa, Hiroyuki

1993-01-01

Cooling water for a divertor cooling system cools the divertor, thereafter, passes through pipelines connecting the exit pipelines of the divertor cooling system and the inlet pipelines of a blanket cooling system and is introduced to the blanket cooling system in a vacuum vessel. It undergoes emission of neutrons, and cooling water in the divertor cooling system containing a great amount of N-16 which is generated by radioactivation of O-16 is introduced to the blanket cooling system in the vacuum vessel by way of pipelines, and after cooling, passes through exit pipelines of the blanket cooling system and is introduced to the outside of the vacuum vessel. Radiation of N-16 in the cooling water is decayed sufficiently with passage of time during cooling of the blanket, thereby enabling to decrease the amount of shielding materials such as facilities and pipelines, and ensure spaces. (N.H.)

Measurement and calculation of radiation sources in the primary cooling system of JOYO

International Nuclear Information System (INIS)

Suzuki, S.; Iizawa, K.; Ohtani, N.; Kobayashi, T.; Horie, J.; Handa, H.

1987-01-01

Production and transfer of radiation sources in the primary cooling system are important consideration in the LMFBR plant from the viewpoint of radiation protection and shielding design. These items were evaluated with calculations and/or measurements in the Japanese experimental fast reactor JOYO. In this study, calculations were made with the DOT3.5 0 two-dimensional discrete ordinate transport code to determine the neutron flux and production rate distributions of radiation sources in the reactor vessel. Using the DOT results, the behavior in primary coolant sodium of the CP (radioactive corrosion products) which were released from the reactor structural material was also calculationally analyzed with the PSYCHE code developed by PNC. These analytical results were compared with the measured results to get the verification of analysis methods and to estimate the accuracy of calculations

Radiation environment and cooling of the Si option for the IT upgrade

CERN Document Server

Belogurov, S; Dijkstra, H; Van Herwijnen, E; Semennikov, A; Souza de Paula, B

2014-01-01

The expected radiation dose for the Si option of the IT upgrade is evaluated based on the experience of run-1. The sensors have to be kept ∼ 20◦C below ambient temperature to avoid thermal runaway. A mock-up has been constructed to test the cooling of the sensors and their electronics with dry cold air. The tests show that the temperatures of the hybrids and sensors can be stabilized and tuned to the required level.

Conceptual development of a building-integrated photovoltaic–radiative cooling system and preliminary performance analysis in Eastern China

International Nuclear Information System (INIS)

Zhao, Bin; Hu, Mingke; Ao, Xianze; Pei, Gang

2017-01-01

Highlights: •A specific spectral characteristic for both PV and RC was proposed. •The PV/RC hybrid system based on spectral characteristic is original. •A thermal model of the system was established and the performance was analyzed. •The performance comparison with the conventional PV system was conducted. •The system shows considerable performance for both PV and RC. -- Abstract: Building-integrated photovoltaic/thermal (BIPV/T) technology has been receiving considerable research attention because of its ability to generate electricity and thermal energy simultaneously. However, space cooling is crucial for buildings in hot regions where space heating is of little use. This study proposed a building-integrated photovoltaic–radiative cooling system (BIPV–RC) that can generate electricity via photovoltaic (PV) conversion during daytime and generate cooling energy via radiative cooling (RC) during nighttime to satisfy the demand in such areas. The selective plate, which is the main component of the BIPV–RC system, exhibits high spectral absorptivity (emissivity) in the PV conversion band of crystalline silicon solar cells and in the atmospheric window band (i.e., 0.3–1.1 μm and 8–13 μm), as well as low spectral absorptivity (emissivity) in other bands. A quasi-steady-state mathematical model was built, and its performance under realistic ambient conditions was analyzed. The electrical efficiencies of the BIPV–RC and conventional BIPV systems were then compared under different solar radiations. Comparison results show that the annual electricity production and cooling energy gain of the BIPV–RC system in Hefei reached 156.74 kW h m −2 (equivalent to 564.26 MJ m −2 ) and 579.91 MJ m −2 , respectively. The total electricity production and cooling energy gain of this system are 96.96% higher than those of the BIPV system. Parametric studies show that the precipitable water vapor amount has remarkable effects on the nocturnal RC performance

Storm Time Variation of Radiative Cooling by Nitric Oxide as Observed by TIMED-SABER and GUVI

Science.gov (United States)

Bharti, Gaurav; Sunil Krishna, M. V.; Bag, T.; Jain, Puneet

2018-02-01

The variation of O/N2 (reference to N2 column density 1017 cm-2) and nitric oxide radiative emission flux exiting the thermosphere have been studied over the Northern Hemisphere during the superstorm event of 7-12 November 2004. The data have been obtained from Global Ultraviolet Imager (GUVI) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the National Aeronautics and Space Administration (NASA)'s Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite. The NO radiative flux is observed to show an anti-correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2, and N2 densities have been calculated using NRLMSISE-00 model over a midlatitude location (55°N,180°E). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The collisional excitation of NO with atomic oxygen is the most dominant process for the total cooling rate. The SABER-retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and Nitric Oxide Empirical Model (NOEM) model. Both these suggest a vary large (3-15 times) increase in NO density during the storm, which is required to account the changes in NO radiative flux. A similar kind of enhancement in NO abundance is also noticed in Student Nitric Oxide Explorer observations during intense geomagnetic storms.

Onderzoeksrapportage duurzaam koelen : EOS Renewable Cooling

OpenAIRE

Broeze, J.; Sluis, van der, S.; Wissink, E.

2010-01-01

For reducing energy use for cooling, alternative methods (that do not rely on electricity) are needed. Renewable cooling is based on naturally available resources such as evaporative cooling, free cooling, phase change materials, ground subcooling, solar cooling, wind cooling, night radiation & storage. The project was aimed to create innovative combinations of these renewable cooling technologies and sophisticated control systems, to design renewable climate systems for various applicati...

Parametrization of the average ionization and radiative cooling rates of carbon plasmas in a wide range of density and temperature

International Nuclear Information System (INIS)

Gil, J.M.; Rodriguez, R.; Florido, R.; Rubiano, J.G.; Mendoza, M.A.; Nuez, A. de la; Espinosa, G.; Martel, P.; Minguez, E.

2013-01-01

In this work we present an analysis of the influence of the thermodynamic regime on the monochromatic emissivity, the radiative power loss and the radiative cooling rate for optically thin carbon plasmas over a wide range of electron temperature and density assuming steady state situations. Furthermore, we propose analytical expressions depending on the electron density and temperature for the average ionization and cooling rate based on polynomial fittings which are valid for the whole range of plasma conditions considered in this work. -- Highlights: ► We compute the average ionization, cooling rates and emissivities of carbon plasmas. ► We compare LTE and NLTE calculations of these magnitudes. ► We perform a parametrization of these magnitudes in a wide range of plasma conditions. ► We provide information about where LTE regime assumption is accurate

Storm-time variation of radiative cooling by Nitric Oxide as observed by TIMED-SABER and GUVI

Science.gov (United States)

Sunil Krishna, M. V.; Bharti, G.; Bag, T.

2017-12-01

The variation of O/N2 and nitric oxide radiative emission flux exiting thermosphere have been studied over northern hemisphere during the super-storm event of November 7-12, 2004. The data have been obtained from GUVI and SABER onboard the NASA's TIMED satellite. The NO radiative flux is observed to show an anti-correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2 and N2 densities have been calculated by using NRLMSISE-00 model over a mid-latitude location (55oN,180oE). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The SABER retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and NOEM model. Both these suggest huge increase in NO density during the storm which is required to account the changes in NO radiative flux.

A comparison of radiation dose to the neurovascular bundles in men with and without prostate brachytherapy-induced erectile dysfunction

International Nuclear Information System (INIS)

Merrick, Gregory S.; Butler, Wayne M.; Dorsey, Anthony T.; Lief, Jonathan H.; Donzella, Joseph G.

2000-01-01

Purpose: The etiology of erectile dysfunction after definitive local therapy for carcinoma of the prostate gland represents a multifactorial phenomenon including neurogenic compromise, venous insufficiency, local trauma, and psychogenic causes. It has been suggested that impotence after prostate brachytherapy is a consequence of excessive radiation dose to the neurovascular bundles (NVB). Herein we evaluate the potential relationship between radiation dose to the NVB and the development of erectile dysfunction following prostate brachytherapy. Methods and Materials: The radiation dose to the NVB was evaluated for 33 patients who developed erectile dysfunction (ED) following brachytherapy plus 21 additional patients who were potent before and subsequent to brachytherapy. Of the 54 patient study group, the median follow up was 37 months, and 25 patients were managed with 125 I as a monotherapeutic approach and 29 received 103 Pd as a boost following 45 Gy of external beam radiation therapy. Radiographic localization of the NVB was performed via a two-dimensional geometric model that placed 3-NVB calculation points on the left and right posterolateral side of each 5-mm CT slice. Parameters evaluated included dose-surface histograms, dose parameters via point doses on each slice, the magnitude of the dose in relationship to the distance from the base, and the relationship between NVB radiation dose in patients with and without ED, patient response to sildenafil and case sequence number. Results: In terms of percent prescribed minimum peripheral dose (% mPD), there was no significant difference in mean neurovascular bundle dose between potent and impotent patients, between the isotopes ( 125 I or 103 Pd), mono- or boost therapy, or side of the prostate for which the overall average was 217% ± 55% of mPD. There was also no significant dosimetric difference in terms of response to sildenafil based on a multivariate analysis which included % mPD and various dose

Cool colored coating and phase change materials as complementary cooling strategies for building cooling load reduction in tropics

International Nuclear Information System (INIS)

Lei, Jiawei; Kumarasamy, Karthikeyan; Zingre, Kishor T.; Yang, Jinglei; Wan, Man Pun; Yang, En-Hua

2017-01-01

Highlights: • Cool colored coating and PCM are two complementary passive cooling strategies. • A PCM cool colored coating system is developed. • The coating reduces cooling energy by 8.5% and is effective yearly in tropical Singapore. - Abstract: Cool colored coating and phase change materials (PCM) are two passive cooling strategies often used separately in many studies and applications. This paper investigated the integration of cool colored coating and PCM for building cooling through experimental and numerical studies. Results showed that cool colored coating and PCM are two complementary passive cooling strategies that could be used concurrently in tropical climate where cool colored coating in the form of paint serves as the “first protection” to reflect solar radiation and a thin layer of PCM forms the “second protection” to absorb the conductive heat that cannot be handled by cool paint. Unlike other climate zones where PCM is only seasonally effective and cool paint is only beneficial during summer, the application of the proposed PCM cool colored coating in building envelope could be effective throughout the entire year with a monthly cooling energy saving ranging from 5 to 12% due to the uniform climatic condition all year round in tropical Singapore.

Nighttime Infrared radiative cooling and opacity inferred by REMS Ground Temperature Sensor Measurements

Science.gov (United States)

Martín-Torres, Javier; Paz Zorzano, María; Pla-García, Jorge; Rafkin, Scot; Lepinette, Alain; Sebastián, Eduardo; Gómez-Elvira, Javier; REMS Team

2013-04-01

Due to the low density of the Martian atmosphere, the temperature of the surface is controlled primarily by solar heating, and infrared cooling to the atmosphere and space, rather than heat exchange with the atmosphere. In the absence of solar radiation the infrared (IR) cooling, and then the nighttime surface temperatures, are directly controlled by soil termal inertia and atmospheric optical thickness (τ) at infrared wavelengths. Under non-wind conditions, and assuming no processes involving latent heat changes in the surface, for a particular site where the rover stands the main parameter controlling the IR cooling will be τ. The minimal ground temperature values at a fixed position may thus be used to detect local variations in the total dust/aerosols/cloud tickness. The Ground Temperature Sensor (GTS) and Air Temperature Sensor (ATS) in the Rover Environmental Monitoring Station (REMS) on board the Mars Science Laboratory (MSL) Curiosity rover provides hourly ground and air temperature measurements respectively. During the first 100 sols of operation of the rover, within the area of low thermal inertia, the minimal nightime ground temperatures reached values between 180 K and 190 K. For this season the expected frost point temperature is 200 K. Variations of up to 10 K have been observed associated with dust loading at Gale at the onset of the dust season. We will use these measurements together with line-by-line radiative transfer simulations using the Full Transfer By Optimized LINe-by-line (FUTBOLIN) code [Martín-Torres and Mlynczak, 2005] to estimate the IR atmospheric opacity and then dust/cloud coverage over the rover during the course of the MSL mission. Monitoring the dust loading and IR nightime cooling evolution during the dust season will allow for a better understanding of the influence of the atmosphere on the ground temperature and provide ground truth to models and orbiter measurements. References Martín-Torres, F. J. and M. G. Mlynczak

Global Cooling: Policies to Cool the World and Offset Global Warming from CO2 Using Reflective Roofs and Pavements

Energy Technology Data Exchange (ETDEWEB)

Akbari, Hashem; Levinson, Ronnen; Rosenfeld, Arthur; Elliot, Matthew

2009-08-28

Increasing the solar reflectance of the urban surface reduce its solar heat gain, lowers its temperatures, and decreases its outflow of thermal infrared radiation into the atmosphere. This process of 'negative radiative forcing' can help counter the effects of global warming. In addition, cool roofs reduce cooling-energy use in air conditioned buildings and increase comfort in unconditioned buildings; and cool roofs and cool pavements mitigate summer urban heat islands, improving outdoor air quality and comfort. Installing cool roofs and cool pavements in cities worldwide is a compelling win-win-win activity that can be undertaken immediately, outside of international negotiations to cap CO{sub 2} emissions. We propose an international campaign to use solar reflective materials when roofs and pavements are built or resurfaced in temperate and tropical regions.

Diagnostics of a stationary MPD-type plasma jet with a HCN laser interferometer

International Nuclear Information System (INIS)

Graser, W.; Hoffmann, P.

1975-01-01

A HCN laser interferometer of the Ashby-Jephcott type operating at a wavelength of 337 μm was used to measure spatially resolved electron densities in a stationary MPD-type plasma jet with non-LTE behavior. Experiments were performed with and without superimposed magnetic fields up to 0.1 T at the exit of the plasma accelerator. Electron densities were obtained within the limits of 5times10 12 and 10 15 cm -3 with an accuracy better than 10%. Within the axially symmetric expanding plasma of about 15-cm average diameter and 50-cm length the radial resolving power came to less than 1 cm. So this technique has proved to be suitable to fill a gap in the diagnostics of stationary magnetized plasmas in the mean range of electron densities. (auth)

Storm time variation of radiative cooling of thermosphere by nitric oxide emission

Science.gov (United States)

Krishna, M. V. Sunil; Bag, Tikemani; Bharti, Gaurav

2016-07-01

The fundamental vibration-rotation band emission (Δν=1, Δ j=0,± 1) by nitric oxide (NO) at 5.3 µm is one of the most important cooling mechanisms in thermosphere. The collisional vibrational excitation of NO(ν=0) by impact with atomic oxygen is the main source of vibrationally excited nitric oxide. The variation of NO density depends on latitude, longitude and season. The present study aims to understand how the radiative flux gets influenced by the severe geomagnetic storm conditions. The variation of Nitric Oxide (NO) radiative flux exiting thermosphere is studied during the superstorm event of 7-12 November, 2004. The observations of TIMED/SABER suggest a strong anti-correlation with the O/N_2 ratio observed by GUVI during the same period. On a global scale the NO radiative flux showed an enhancement during the main phase on 8 November, 2004, whereas maximum depletion in O/N_2 is observed on 10 November, 2004. Both O/N_2 and NO radiative flux were found to propagate equatorward due to the effect of meridional wind resulting from joule and particle heating in polar region. Larger penetrations is observed in western longitude sectors. These observed variations are effectively connected to the variations in neutral densities. In the equatorial sectors, O/N_2 shows enhancement but almost no variation in radiative flux is observed. The possible reasons for the observed variations in NO radiative emission and O/N_2 ratios are discussed in the light of equator ward increase in the densities and prompt penetration.

Production of radiatively cooled hypersonic plasma jets and links to astrophysical jets

International Nuclear Information System (INIS)

Lebedev, S V; Ciardi, A; Ampleford, D J; Bland, S N; Bott, S C; Chittenden, J P; Hall, G N; Rapley, J; Jennings, C; Sherlock, M; Frank, A; Blackman, E G

2005-01-01

We present results of high energy density laboratory experiments on the production of supersonic radiatively cooled plasma jets with dimensionless parameters (Mach number ∼30, cooling parameter ∼1 and density contrast ρ j /ρ a ∼ 10) similar to those in young stellar objects jets. The jets are produced using two modifications of wire array Z-pinch driven by 1 MA, 250 ns current pulse of MAGPIE facility at Imperial College, London. In the first set of experiments the produced jets are purely hydrodynamic and are used to study deflection of the jets by the plasma cross-wind, including the structure of internal oblique shocks in the jets. In the second configuration the jets are driven by the pressure of the toroidal magnetic field and this configuration is relevant to the astrophysical models of jet launching mechanisms. Modifications of the experimental configuration allowing the addition of the poloidal magnetic field and angular momentum to the jets are also discussed. We also present three-dimensional resistive magneto-hydrodynamic simulations of the experiments and discuss the scaling of the experiments to the astrophysical systems

Chronic radiation-induced leukemogenesis: alterations of hematopoietic progenitor repair functions during preclinical phases

International Nuclear Information System (INIS)

Seed, T.M.; Kaspar, L.V.; Grdina, D.J.; Frazier, M.E.

1987-01-01

Chronic exposure to low daily doses of whole-body gamma irradiation elicits a high incidence of myeloid leukemia (ML) and related myeloproliferative diseases (MPD) in beagles. Previously, the authors identified and partially characterized a four-phase sequence of evolving MPD as a consequence of chronic radiation exposure. With a focus on preclinical alterations in granulocyte/monocyte-committed stem cells, they have identified two critical events in the process: (i) an early event, involving the coupling of acquired radioresistance of the stem cell with renewed proliferative capacity; and (ii) a late event, involving acquired autocrine functions and associated change in stem cell clonality. In terms of the early event, repair-associated parameters are currently being examined on the cellular level by both split-dose and low dose-rate-type assays with survival enhancement used as the measured end point. On the molecular level, these parameters are examined by microfluorometric alkaline elution assays with DNA damage and repair used as end points

CFD-simulation of radiator for air cooling of microprocessors in a limitided space

Directory of Open Access Journals (Sweden)

Trofimov V. E.

2016-12-01

Full Text Available One of the final stages of microprocessors development is heat test. This procedure is performed on a special stand, the main element of which is the switching PCB with one or more mounted microprocessor sockets, chipsets, interfaces, jumpers and other components which provide various modes of microprocessor operation. The temperature of microprocessor housing is typically changed using thermoelectric module. The cold surface of the module with controlled temperature is in direct thermal contact with the microprocessor housing designed for cooler installation. On the hot surface of the module a radiator is mounted. The radiator dissipates the cumulative heat flow from both the microprocessor and the module. High density PCB layout, the requirement of free access to the jumpers and interfaces, and the presence of numerous sensors limit the space for radiator mounting and require the use of an extremely compact radiator, especially in air cooling conditions. One of the possible solutions for this problem may reduce the area of the radiator heat-transfer surfaces due to a sharp growth of the heat transfer coefficient without increasing the air flow rate. To ensure a sharp growth of heat transfer coefficient on the heat-transfer surface one should make in the surface one or more dead-end cavities into which the impact air jets would flow. CFD simulation of this type of radiator has been conducted. The heat-aerodynamic characteristics and design recommendations for removing heat from microprocessors in a limited space have been determined.

Human radiation experiments: Looking beyond the headlines

International Nuclear Information System (INIS)

Cohen, B.L.

1994-01-01

There has been a great deal of publicity recently about experiments supported by the U.S. Department of Energy and its predecessors, the Atomic Energy Commission (AEC) and the Energy Research and Development Administration, in which human subjects were exposed to radiation. Media stories give the impression that these experiments were done in secret, without informing the subjects, and that these subjects suffered horrible consequences. As a prelude to understanding the situation, it is useful to review the bases for judgement in deciding on this type of experiment. When it was first recognized that radiation can be harmful, national and international groups promulgated the concept of open-quotes maximum permissible doseclose quotes (MPD) on the basis that with a comfortable factor of safety (e.g., a factor of 10), there was no evidence of harm at that level. This had always been the principal method of providing safety, applied to everything from chemicals to bridges. In the 1940s, the MPD was 100 mrem per day, and it was assumed that there would be no harmful health impacts at that level. Current regulations require that experiments involving radiation exposure to human subjects be approved by a review board at the institution where they are carried out. National guidelines for these review boards require that whole-body doses to subjects be kept below 2 rem except in extraordinary circumstances. As an example of how these regulations are currently implemented, consider positron emission tomography (PET), a very active medical research topic for the past few years. In one major medical center, this involves exposing about 300 subjects per year, normally recruited through newspaper advertisements, with an average dose of about 400 mrem to each. There are about 50 comparable medical centers throughout the United States

System for cooling hybrid vehicle electronics, method for cooling hybrid vehicle electronics

Science.gov (United States)

France, David M.; Yu, Wenhua; Singh, Dileep; Zhao, Weihuan

2017-11-21

The invention provides a single radiator cooling system for use in hybrid electric vehicles, the system comprising a surface in thermal communication with electronics, and subcooled boiling fluid contacting the surface. The invention also provides a single radiator method for simultaneously cooling electronics and an internal combustion engine in a hybrid electric vehicle, the method comprising separating a coolant fluid into a first portion and a second portion; directing the first portion to the electronics and the second portion to the internal combustion engine for a time sufficient to maintain the temperature of the electronics at or below 175.degree. C.; combining the first and second portion to reestablish the coolant fluid; and treating the reestablished coolant fluid to the single radiator for a time sufficient to decrease the temperature of the reestablished coolant fluid to the temperature it had before separation.

Coherent electron cooling

Energy Technology Data Exchange (ETDEWEB)

Litvinenko,V.

2009-05-04

Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

Cyclotron resonance cooling by strong laser field

International Nuclear Information System (INIS)

Tagcuhi, Toshihiro; Mima, Kunioka

1995-01-01

Reduction of energy spread of electron beam is very important to increase a total output radiation power in free electron lasers. Although several cooling systems of particle beams such as a stochastic cooling are successfully operated in the accelerator physics, these cooling mechanisms are very slow and they are only applicable to high energy charged particle beams of ring accelerators. We propose here a new concept of laser cooling system by means of cyclotron resonance. Electrons being in cyclotron motion under a strong magnetic field can resonate with circular polarized electromagnetic field, and the resonance take place selectively depending on the velocity of the electrons. If cyclotron frequency of electrons is equal to the frequency of the electromagnetic field, they absorb the electromagnetic field energy strongly, but the other electrons remain unchanged. The absorbed energy will be converted to transverse kinetic energy, and the energy will be dumped into the radiation energy through bremastrahlung. To build a cooling system, we must use two laser beams, where one of them is counter-propagating and the other is co-propagating with electron beam. When the frequency of the counter-propagating laser is tuned with the cyclotron frequency of fast electrons and the co-propagating laser is tuned with the cyclotron frequency of slow electrons, the energy of two groups will approach and the cooling will be achieved. We solve relativistic motions of electrons with relativistic radiation dumping force, and estimate the cooling rate of this mechanism. We will report optimum parameters for the electron beam cooling system for free electron lasers

Radiative cooling to deep sub-freezing temperatures through a 24-h day-night cycle

Science.gov (United States)

Chen, Zhen; Zhu, Linxiao; Raman, Aaswath; Fan, Shanhui

2016-12-01

Radiative cooling technology utilizes the atmospheric transparency window (8-13 μm) to passively dissipate heat from Earth into outer space (3 K). This technology has attracted broad interests from both fundamental sciences and real world applications, ranging from passive building cooling, renewable energy harvesting and passive refrigeration in arid regions. However, the temperature reduction experimentally demonstrated, thus far, has been relatively modest. Here we theoretically show that ultra-large temperature reduction for as much as 60 °C from ambient is achievable by using a selective thermal emitter and by eliminating parasitic thermal load, and experimentally demonstrate a temperature reduction that far exceeds previous works. In a populous area at sea level, we have achieved an average temperature reduction of 37 °C from the ambient air temperature through a 24-h day-night cycle, with a maximal reduction of 42 °C that occurs when the experimental set-up enclosing the emitter is exposed to peak solar irradiance.

Radiative cooling to deep sub-freezing temperatures through a 24-h day-night cycle.

Science.gov (United States)

Chen, Zhen; Zhu, Linxiao; Raman, Aaswath; Fan, Shanhui

2016-12-13

Radiative cooling technology utilizes the atmospheric transparency window (8-13 μm) to passively dissipate heat from Earth into outer space (3 K). This technology has attracted broad interests from both fundamental sciences and real world applications, ranging from passive building cooling, renewable energy harvesting and passive refrigeration in arid regions. However, the temperature reduction experimentally demonstrated, thus far, has been relatively modest. Here we theoretically show that ultra-large temperature reduction for as much as 60 °C from ambient is achievable by using a selective thermal emitter and by eliminating parasitic thermal load, and experimentally demonstrate a temperature reduction that far exceeds previous works. In a populous area at sea level, we have achieved an average temperature reduction of 37 °C from the ambient air temperature through a 24-h day-night cycle, with a maximal reduction of 42 °C that occurs when the experimental set-up enclosing the emitter is exposed to peak solar irradiance.

Self-limitation of impurity production by radiation cooling at the edge of a fusion plasma

International Nuclear Information System (INIS)

Neuhauser, J.; Lackner, K.; Wunderlich, R.

1982-04-01

The influence of radiation cooling at the edge of a fusion plasma on the plasma-wall interaction is numerically studied for parameters typical of the ZEPHYR ignition experiment. Various transport and impurity influx models and different external heating methods are studied using the 1D tokamak transport code BALDUR developed at Princeton. The results demonstrate the self-consistent formation of a radiating boundary layer (photosphere) for a wide range of parameters, limiting the impurity concentration in the plasma to a tolerable value. While the plasma behaviour is rather insensitive to model assumptions, the sputtering rate and the corresponding wall erosion depend on various parameters. Methods for external control of the photosphere and - more important - of the wall erosion are also discussed. (orig.)

Proton-antiproton colliding beam electron cooling

International Nuclear Information System (INIS)

Derbenev, Ya.S.; Skrinskij, A.N.

1981-01-01

A possibility of effective cooling of high-energy pp tilde beams (E=10 2 -10 3 GeV) in the colliding mode by accompanying radiationally cooled electron beam circulating in an adjacent storage ring is studied. The cooling rate restrictions by the pp tilde beam interaction effects while colliding and the beam self-heating effect due to multiple internal scattering are considered. Some techniques permitting to avoid self-heating of a cooling electron beam or suppress its harmful effect on a heavy particle beam cooling are proposed. According to the estimations the cooling time of 10 2 -10 3 s order can be attained [ru

Effects of Convective Aggregation on Radiative Cooling and Precipitation in a CRM

Science.gov (United States)

Naegele, A. C.; Randall, D. A.

2017-12-01

In the global energy budget, the atmospheric radiative cooling (ARC) is approximately balanced by latent heating, but on regional scales, the ARC and precipitation rates are inversely related. We use a cloud-resolving model to explore how the relationship between precipitation and the ARC is affected by convective aggregation, in which the convective activity is confined to a small portion of the domain that is surrounded by a much larger region of dry, subsiding air. Sensitivity tests show that the precipitation rate and ARC are highly sensitive to both SST and microphysics; a higher SST and 1-moment microphysics both act to increase the domain-averaged ARC and precipitation rates. In all simulations, both the domain-averaged ARC and precipitation rates increased due to convective aggregation, resulting in a positive temporal correlation. Furthermore, the radiative effect of clouds in these simulations is to decrease the ARC. This finding is consistent with our observational results of the cloud effect on the ARC, and has implications for convective aggregation and the geographic extent in which it can occur.

Dry cooling with night cool storage to enhance solar power plants performance in extreme conditions areas

International Nuclear Information System (INIS)

Muñoz, J.; Martínez-Val, J.M.; Abbas, R.; Abánades, A.

2012-01-01

Highlights: ► Solar thermo-electric power plants with thermal storage for condenser cooling. ► Technology to mitigate the negative effect on Rankine cycles of the day-time high temperatures in deserts. ► Electricity production augmentation in demand-peak hours by the use of day-night temperature difference. -- Abstract: Solar thermal power plants are usually installed in locations with high yearly average solar radiation, often deserts. In such conditions, cooling water required for thermodynamic cycles is rarely available. Moreover, when solar radiation is high, ambient temperature is very high as well; this leads to excessive condensation temperature, especially when air-condensers are used, and decreases the plant efficiency. However, temperature variation in deserts is often very high, which drives to relatively low temperatures during the night. This fact can be exploited with the use of a closed cooling system, so that the coolant (water) is chilled during the night and store. Chilled water is then used during peak temperature hours to cool the condenser (dry cooling), thus enhancing power output and efficiency. The present work analyzes the performance improvement achieved by night thermal cool storage, compared to its equivalent air cooled power plant. Dry cooling is proved to be energy-effective for moderately high day–night temperature differences (20 °C), often found in desert locations. The storage volume requirement for different power plant efficiencies has also been studied, resulting on an asymptotic tendency.

Magnetic reconnection in the low solar chromosphere with a more realistic radiative cooling model

Science.gov (United States)

Ni, Lei; Lukin, Vyacheslav S.; Murphy, Nicholas A.; Lin, Jun

2018-04-01

Magnetic reconnection is the most likely mechanism responsible for the high temperature events that are observed in strongly magnetized locations around the temperature minimum in the low solar chromosphere. This work improves upon our previous work [Ni et al., Astrophys. J. 852, 95 (2018)] by using a more realistic radiative cooling model computed from the OPACITY project and the CHIANTI database. We find that the rate of ionization of the neutral component of the plasma is still faster than recombination within the current sheet region. For low β plasmas, the ionized and neutral fluid flows are well-coupled throughout the reconnection region resembling the single-fluid Sweet-Parker model dynamics. Decoupling of the ion and neutral inflows appears in the higher β case with β0=1.46 , which leads to a reconnection rate about three times faster than the rate predicted by the Sweet-Parker model. In all cases, the plasma temperature increases with time inside the current sheet, and the maximum value is above 2 ×104 K when the reconnection magnetic field strength is greater than 500 G. While the more realistic radiative cooling model does not result in qualitative changes of the characteristics of magnetic reconnection, it is necessary for studying the variations of the plasma temperature and ionization fraction inside current sheets in strongly magnetized regions of the low solar atmosphere. It is also important for studying energy conversion during the magnetic reconnection process when the hydrogen-dominated plasma approaches full ionization.

Stability, structure, and evolution of cool loops

International Nuclear Information System (INIS)

Cally, P.S.; Robb, T.D.

1991-01-01

The criteria for the existence and stability of cool loops are reexamined. It is found that the stability of the loops strongly depends on the form of the heating and radiative loss functions and that if the Ly-alpha peak which appears in most calculations of the radiative loss function is real, cool loops are almost certainly unstable. Removing the hydrogen contribution from the recent loss function Q(T) by Cook et al. (1989) does not produce the much-used result, Q proportional to T-cubed, which is so favorable to cool loop stability. Even using the probably unrealistically favorable loss function Q1 of Cook et al. with the hydrogen contribution removed, the maximum temperature attainable in stable cool loops is a factor of 2-3 too small to account for the excess emission observed in lower transition region lines. Dynamical simulations of cool loop instabilities reveal that the final state of such a model is the hot loop equilibrium. 26 refs

AGN Heating in Simulated Cool-core Clusters

Energy Technology Data Exchange (ETDEWEB)

Li, Yuan; Ruszkowski, Mateusz [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Bryan, Greg L., E-mail: yuanlium@umich.edu [Department of Astronomy, Columbia University, Pupin Physics Laboratories, New York, NY 10027 (United States)

2017-10-01

We analyze heating and cooling processes in an idealized simulation of a cool-core cluster, where momentum-driven AGN feedback balances radiative cooling in a time-averaged sense. We find that, on average, energy dissipation via shock waves is almost an order of magnitude higher than via turbulence. Most of the shock waves in the simulation are very weak shocks with Mach numbers smaller than 1.5, but the stronger shocks, although rare, dissipate energy more effectively. We find that shock dissipation is a steep function of radius, with most of the energy dissipated within 30 kpc, more spatially concentrated than radiative cooling loss. However, adiabatic processes and mixing (of post-shock materials and the surrounding gas) are able to redistribute the heat throughout the core. A considerable fraction of the AGN energy also escapes the core region. The cluster goes through cycles of AGN outbursts accompanied by periods of enhanced precipitation and star formation, over gigayear timescales. The cluster core is under-heated at the end of each cycle, but over-heated at the peak of the AGN outburst. During the heating-dominant phase, turbulent dissipation alone is often able to balance radiative cooling at every radius but, when this is occurs, shock waves inevitably dissipate even more energy. Our simulation explains why some clusters, such as Abell 2029, are cooling dominated, while in some other clusters, such as Perseus, various heating mechanisms including shock heating, turbulent dissipation and bubble mixing can all individually balance cooling, and together, over-heat the core.

Effects of chronic radiation exposure on the reproduction of dogs

International Nuclear Information System (INIS)

Shifrine, M.; Kawakami, T.G.; Rasmussen, C.

1984-01-01

During studies on radiation leukemogenesis 7 dogs were exposed to 4.4 R/day starting at 150 days of age. Three of these dogs were females. To determine whether the exposure to chronic irradiation affected their reproductive capacity the three bitches were bred. Two of the bitches did not conceive, and one of these died shortly thereafter from myeloproliferative disease (MPD) which could have been a factor. The third bitch whelped 7 pups, one of which died shortly after birth, and the other 6 are healthy 2 months after birth. 1 table

Hyper-cooling in the nocturnal boundary layer: the Ramdas paradox

International Nuclear Information System (INIS)

Mukund, V; Ponnulakshmi, V K; Singh, D K; Subramanian, G; Sreenivas, K R

2010-01-01

Characterizing the interaction between turbulence and radiative processes is necessary for understanding the nocturnal atmospheric boundary layer. The subtle nature of the interaction is exemplified in a phenomenon called the 'Ramdas paradox' or the 'lifted temperature minimum' (LTM), involving preferential cooling near the Earth's surface. The prevailing explanation for the LTM (the VSN model, Vasudeva Murthy et al (1993 Phil. Trans. R. Soc. A 344 183-206)) invokes radiative exchange in a homogeneous nocturnal atmosphere to predict a large cooling of the near-surface air layers. It is shown here that the cooling predicted by the VSN model is spurious, and that any preferential cooling can occur only in a heterogeneous atmosphere. The underlying error is fundamental, and occurs to varying degrees in a wide class of radiative models, in a flux-emissivity formulation, the VSN model being a prominent example. We, for the first time, propose the correct flux-emissivity formulation that eliminates spurious cooling. Results from field observations and laboratory experiments presented here, however, show that the near-surface radiative cooling is real; near-surface cooling rates can be orders of magnitude higher than values elsewhere in the boundary layer. The results presented include the dependence of the LTM on turbulence, the surface emissivity and the thermal inertia of the ground. It is proposed that aerosols provide the heterogeneity needed for the preferential cooling mechanism. Turbulence, by determining the aerosol concentration distribution over the relevant length scales, plays a key role in the phenomenon. Experimental evidence is presented to support this hypothesis.

Hyper-cooling in the nocturnal boundary layer: the Ramdas paradox

Energy Technology Data Exchange (ETDEWEB)

Mukund, V; Ponnulakshmi, V K; Singh, D K; Subramanian, G; Sreenivas, K R, E-mail: krs@jncasr.ac.in [Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore (India)

2010-12-15

Characterizing the interaction between turbulence and radiative processes is necessary for understanding the nocturnal atmospheric boundary layer. The subtle nature of the interaction is exemplified in a phenomenon called the 'Ramdas paradox' or the 'lifted temperature minimum' (LTM), involving preferential cooling near the Earth's surface. The prevailing explanation for the LTM (the VSN model, Vasudeva Murthy et al (1993 Phil. Trans. R. Soc. A 344 183-206)) invokes radiative exchange in a homogeneous nocturnal atmosphere to predict a large cooling of the near-surface air layers. It is shown here that the cooling predicted by the VSN model is spurious, and that any preferential cooling can occur only in a heterogeneous atmosphere. The underlying error is fundamental, and occurs to varying degrees in a wide class of radiative models, in a flux-emissivity formulation, the VSN model being a prominent example. We, for the first time, propose the correct flux-emissivity formulation that eliminates spurious cooling. Results from field observations and laboratory experiments presented here, however, show that the near-surface radiative cooling is real; near-surface cooling rates can be orders of magnitude higher than values elsewhere in the boundary layer. The results presented include the dependence of the LTM on turbulence, the surface emissivity and the thermal inertia of the ground. It is proposed that aerosols provide the heterogeneity needed for the preferential cooling mechanism. Turbulence, by determining the aerosol concentration distribution over the relevant length scales, plays a key role in the phenomenon. Experimental evidence is presented to support this hypothesis.

Hyper-cooling in the nocturnal boundary layer: the Ramdas paradox

Science.gov (United States)

Mukund, V.; Ponnulakshmi, V. K.; Singh, D. K.; Subramanian, G.; Sreenivas, K. R.

2010-12-01

Characterizing the interaction between turbulence and radiative processes is necessary for understanding the nocturnal atmospheric boundary layer. The subtle nature of the interaction is exemplified in a phenomenon called the 'Ramdas paradox' or the 'lifted temperature minimum' (LTM), involving preferential cooling near the Earth's surface. The prevailing explanation for the LTM (the VSN model, Vasudeva Murthy et al (1993 Phil. Trans. R. Soc. A 344 183-206)) invokes radiative exchange in a homogeneous nocturnal atmosphere to predict a large cooling of the near-surface air layers. It is shown here that the cooling predicted by the VSN model is spurious, and that any preferential cooling can occur only in a heterogeneous atmosphere. The underlying error is fundamental, and occurs to varying degrees in a wide class of radiative models, in a flux-emissivity formulation, the VSN model being a prominent example. We, for the first time, propose the correct flux-emissivity formulation that eliminates spurious cooling. Results from field observations and laboratory experiments presented here, however, show that the near-surface radiative cooling is real; near-surface cooling rates can be orders of magnitude higher than values elsewhere in the boundary layer. The results presented include the dependence of the LTM on turbulence, the surface emissivity and the thermal inertia of the ground. It is proposed that aerosols provide the heterogeneity needed for the preferential cooling mechanism. Turbulence, by determining the aerosol concentration distribution over the relevant length scales, plays a key role in the phenomenon. Experimental evidence is presented to support this hypothesis.

Rotating bubble membrane radiator

Science.gov (United States)

Webb, Brent J.; Coomes, Edmund P.

1988-12-06

A heat radiator useful for expelling waste heat from a power generating system aboard a space vehicle is disclosed. Liquid to be cooled is passed to the interior of a rotating bubble membrane radiator, where it is sprayed into the interior of the bubble. Liquid impacting upon the interior surface of the bubble is cooled and the heat radiated from the outer surface of the membrane. Cooled liquid is collected by the action of centrifical force about the equator of the rotating membrane and returned to the power system. Details regarding a complete space power system employing the radiator are given.

Cooling device in thermonuclear device

International Nuclear Information System (INIS)

Honda, Tsutomu.

1988-01-01

Purpose: To prevent loss of cooling effect over the entire torus structure directly after accidental toubles in a cooling device of a thermonuclear device. Constitution: Coolant recycling means of a cooling device comprises two systems, which are alternately connected with in-flow pipeways and exit pipeways of adjacent modules. The modules are cooled by way of the in-flow pipeways and the exist pipeways connected to the respective modules by means of the coolant recycling means corresponding to the respective modules. So long as one of the coolant recycling means is kept operative, since every one other modules of the torus structure is still kept cooled, the heat generated from the module put therebetween, for which the coolant recycling is interrupted, is removed by means of heat conduction or radiation from the module for which the cooling is kept continued. No back-up emergency cooling system is required and it can provide high economic reliability. (Kamimura, M.)

Radiant cooling of an enclosure

International Nuclear Information System (INIS)

Chebihi, Abdeslam; Byun, Ki-Hong; Wen Jin; Smith, Theodore F.

2006-01-01

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

Gas cooled reactors

International Nuclear Information System (INIS)

Kojima, Masayuki.

1985-01-01

Purpose: To enable direct cooling of reactor cores thereby improving the cooling efficiency upon accidents. Constitution: A plurality sets of heat exchange pipe groups are disposed around the reactor core, which are connected by way of communication pipes with a feedwater recycling device comprising gas/liquid separation device, recycling pump, feedwater pump and emergency water tank. Upon occurrence of loss of primary coolants accidents, the heat exchange pipe groups directly absorb the heat from the reactor core through radiation and convection. Although the water in the heat exchange pipe groups are boiled to evaporate if the forcive circulation is interrupted by the loss of electric power source, water in the emergency tank is supplied due to the head to the heat exchange pipe groups to continue the cooling. Furthermore, since the heat exchange pipe groups surround the entire circumference of the reactor core, cooling is carried out uniformly without resulting deformation or stresses due to the thermal imbalance. (Sekiya, K.)

Processes influencing cooling of reactor effluents

International Nuclear Information System (INIS)

Magoulas, V.E.; Murphy, C.E. Jr.

1982-01-01

Discharge of heated reactor cooling water from SRP reactors to the Savannah River is through sections of stream channels into the Savannah River Swamp and from the swamp into the river. Significant cooling of the reactor effluents takes place in both the streams and swamp. The majority of the cooling is through processes taking place at the surface of the water. The major means of heat dissipation are convective transfer of heat to the air, latent heat transfer through evaporation and radiative transfer of infrared radiation. A model was developed which incorporates the effects of these processes on stream and swamp cooling of reactor effluents. The model was used to simulate the effect of modifications in the stream environment on the temperature of water flowing into the river. Environmental effects simulated were the effect of changing radiant heat load, the effect of changes in tree canopy density in the swamp, the effect of total removal of trees from the swamp, and the effect of diverting the heated water from L reactor from Steel Creek to Pen Branch. 6 references, 7 figures

Simulation of an active cooling system for photovoltaic modules

International Nuclear Information System (INIS)

Abdelhakim, Lotfi

2016-01-01

Photovoltaic cells are devices that convert solar radiation directly into electricity. However, solar radiation increases the photovoltaic cells temperature [1] [2]. The temperature has an influence on the degradation of the cell efficiency and the lifetime of a PV cell. This work reports on a water cooling technique for photovoltaic panel, whereby the cooling system was placed at the front surface of the cells to dissipate excess heat away and to block unwanted radiation. By using water as a cooling medium for the photovoltaic solar cells, the overheating of closed panel is greatly reduced without prejudicing luminosity. The water also acts as a filter to remove a portion of solar spectrum in the infrared band but allows transmission of the visible spectrum most useful for the PV operation. To improve the cooling system efficiency and electrical efficiency, uniform flow rate among the cooling system is required to ensure uniform distribution of the operating temperature of the PV cells. The aims of this study are to develop a 3D thermal model to simulate the cooling and heat transfer in Photovoltaic panel and to recommend a cooling technique for the PV panel. The velocity, pressure and temperature distribution of the three-dimensional flow across the cooling block were determined using the commercial package, Fluent. The second objective of this work is to study the influence of the geometrical dimensions of the panel, water mass flow rate and water inlet temperature on the flow distribution and the solar panel temperature. The results obtained by the model are compared with experimental results from testing the prototype of the cooling device.

Simulation of an active cooling system for photovoltaic modules

Energy Technology Data Exchange (ETDEWEB)

Abdelhakim, Lotfi [Széchenyi István University of Applied Sciences, Department of Mathematics, P.O.Box 701, H-9007 Győr (Hungary)

2016-06-08

Photovoltaic cells are devices that convert solar radiation directly into electricity. However, solar radiation increases the photovoltaic cells temperature [1] [2]. The temperature has an influence on the degradation of the cell efficiency and the lifetime of a PV cell. This work reports on a water cooling technique for photovoltaic panel, whereby the cooling system was placed at the front surface of the cells to dissipate excess heat away and to block unwanted radiation. By using water as a cooling medium for the photovoltaic solar cells, the overheating of closed panel is greatly reduced without prejudicing luminosity. The water also acts as a filter to remove a portion of solar spectrum in the infrared band but allows transmission of the visible spectrum most useful for the PV operation. To improve the cooling system efficiency and electrical efficiency, uniform flow rate among the cooling system is required to ensure uniform distribution of the operating temperature of the PV cells. The aims of this study are to develop a 3D thermal model to simulate the cooling and heat transfer in Photovoltaic panel and to recommend a cooling technique for the PV panel. The velocity, pressure and temperature distribution of the three-dimensional flow across the cooling block were determined using the commercial package, Fluent. The second objective of this work is to study the influence of the geometrical dimensions of the panel, water mass flow rate and water inlet temperature on the flow distribution and the solar panel temperature. The results obtained by the model are compared with experimental results from testing the prototype of the cooling device.

Method of 16N generation for test of radiation controlled channels at nuclear power stations with water-cooled reactors

International Nuclear Information System (INIS)

Khryachkov, V.A.; Bondarenko, I.P.; Dvornikov, P.A.; Zhuravlev, B.V.; Kovtun, S.N.; Khromyleva, T.A.; Pavlov, A.V.; Roshchin, N.G.

2012-01-01

The preferences of nuclear reaction use for radiation control channels test in water-cooled power reactors have been analyzed in the paper. The new measurements for more accurate determination of reaction cross section energy dependence have been carried out. A set of new methods for background reducing and improvement of events determination reliability has also been developed [ru

Deposition of tellurium films by decomposition of electrochemically-generated H{sub 2}Te: application to radiative cooling devices

Energy Technology Data Exchange (ETDEWEB)

Engelhard, T.; Jones, E.D.; Viney, I. [Coventry Univ. (United Kingdom). Centre for Data Storage Mater.; Mastai, Y.; Hodes, G. [Department of Materials and Interfaces, Weizmann Institute of Science, 76100, Rehovot (Israel)

2000-07-17

The preparation of homogenous, large area thin layers of tellurium on thin polyethylene foils is described. The tellurium was formed by room temperature decomposition of electrochemically generated H{sub 2}Te. Pre-treatment of the polyethylene substrates with KMnO{sub 4} to give a Mn-oxide layer was found to improve the Te adhesion and homogeneity. Optical characterization of the layers was performed using UV/VIS/NIR spectroscopy. Such coatings have favorable characteristics for use as solar radiation shields in radiative cooling devices. The simplicity of generation of the very unstable H{sub 2}Te was also exploited to demonstrate formation of size-quantized CdTe nanocrystals. (orig.)

Relativistic Turbulence with Strong Synchrotron and Synchrotron-Self-Compton Cooling

Science.gov (United States)

Uzdensky, D. A.

2018-03-01

Many relativistic plasma environments in high-energy astrophysics, including pulsar wind nebulae, hot accretion flows onto black holes, relativistic jets in active galactic nuclei and gamma-ray bursts, and giant radio lobes, are naturally turbulent. The plasma in these environments is often so hot that synchrotron and inverse-Compton (IC) radiative cooling becomes important. In this paper we investigate the general thermodynamic and radiative properties (and hence the observational appearance) of an optically thin relativistically hot plasma stirred by driven magnetohydrodynamic (MHD) turbulence and cooled by radiation. We find that if the system reaches a statistical equilibrium where turbulent heating is balanced by radiative cooling, the effective electron temperature tends to attain a universal value θ = kT_e/m_e c^2 ˜ 1/√{τ_T}, where τT = neσTL ≪ 1 is the system's Thomson optical depth, essentially independent of the strength of turbulent driving and hence of the magnetic field. This is because both MHD turbulent dissipation and synchrotron cooling are proportional to the magnetic energy density. We also find that synchrotron self-Compton (SSC) cooling and perhaps a few higher-order IC components are automatically comparable to synchrotron in this regime. The overall broadband radiation spectrum then consists of several distinct components (synchrotron, SSC, etc.), well separated in photon energy (by a factor ˜ τ_T^{-1}) and roughly equal in power. The number of IC peaks is checked by Klein-Nishina effects and depends logarithmically on τT and the magnetic field. We also examine the limitations due to synchrotron self-absorption, explore applications to Crab PWN and blazar jets, and discuss links to radiative magnetic reconnection.

Investigations of radiation pressure : optical side-band cooling of a trampoline resonator and the effect of superconductivity on the Casimir force

NARCIS (Netherlands)

Eerkens, H.J.

2017-01-01

This thesis consists of two subjects, that are both a consequence of radiation pressure. In optomechanics, light is used to influence the motion of a trampoline resonator. It is possible to slow down this motion, cooling it from room temperature to an effective temperature of several milllikelvins,

Heat Transfer and Cooling Techniques at Low Temperature

CERN Document Server

Baudouy, B

2014-07-17

The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

Heat Transfer and Cooling Techniques at Low Temperature

Energy Technology Data Exchange (ETDEWEB)

Baudouy, B [Saclay (France)

2014-07-01

The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

The CNEN Helium-Caesium Blow-Down MPD Facility and Experiments with a Prototype Duct

Energy Technology Data Exchange (ETDEWEB)

Bertolini, E.; Toschi, R. [CNEN, Frascati (Italy); Lindley, B. C. [C.A. Parsons and Co. Ltd (United Kingdom); Brown, R.; McNab, I. R. [International Research and Development Co. Ltd., Newcastle Upon Tyne (United Kingdom)

1966-11-15

The CNEN blow-down loop has been designed to study a helium-caesium MPD generator with particular regard to non-equilibrium ionization effects. An operating condition of the loop is: gas mass flow 0.2 kg/sec, seed fraction 1 at, wt.%, useful pulse duration 20 sec, stagnation temperature 2000 Degree-Sign K, stagnation pressure 5 atm abs, thermal power 1.6 MW, Mach number 0.6, magnetic field 4 Wb/m2, total impurity level less than 100 ppm. A sufficiently wide range of the stagnation conditions can be obtained with the present arrangement of the loop (temperature up to 2000*K, pressure from slightly sub-atmospheric to 6atmabs, gas mass flow from 50 g/sec to 400 g/sec, seed fraction from 0.1 to 2 at. wt.%. The storage heater is an alumina pebble bed electrically heated with tungsten elements and thermally insulated with zirconia fibre; the thermal capacity at 2000 Degree-Sign K is about 1000 MJ. Pure helium is obtained by evaporation of liquid helium at between 4.5 and 5 Degree-Sign K; liquid caesium is injected into a limited section of the pebble bed to provide a mixture of the two gases uniform in density and temperature. The duct is made of boron nitride (5 cm x 3 cm x 22 cm) with 25 pairs of tantalum electrodes whose geometry (electrode width 3 mm, segmentation pitch 9 mm) should prevent current leakage between adjacent electrodes; the duct walls and transfer can be pre-heated up to 1700 Degree-Sign K. A magnetic field of 4 Wb/m{sup 2} is obtained with a pulsed cryogenic magnet with pulse duration of 6 sec. Two series of experiments have been completed to assess the feasibility of the helium-caesium heating system and the generator duct. Heating system experiments, (a) Compatibility of alumina with tungsten, tantalum and caesium, with thermal cycling at 2000 Degree-Sign K; (b) Purification of zirconia fibre and its behaviour at high temperature, with thermal cycling at 2000 Degree-Sign K; (c) Capability of an alumina pebble bed of evaporating, heating and mixing

Performance evaluation on cool roofs for green remodeling

Science.gov (United States)

Yun, Yosun; Cho, Dongwoo; Cho, Kyungjoo

2018-06-01

Cool roofs refer that maximize heat emission, and minimize the absorption of solar radiation energy, by applying high solar reflectance paints, or materials to roofs or rooftops. The application of cool roofs to existing buildings does not need to take structural issues into consideration, as rooftop greening, is an alternative that can be applied to existing buildings easily. This study installed a cool roofs on existing buildings, and evaluated the performances, using the results to propose certification standards for green remodeling, considering the cool roof-related standards.

Pathological consequences of chronic low daily dose gamma irradiation

Energy Technology Data Exchange (ETDEWEB)

Seed, T.M.; Miller, A.C.; Ramakrishnan, N. [Armed Forces Radiobiology Research Inst., Bethesda, MD (United States); Fritz, T.E.

2000-07-01

The quantitative relationships between the chronic radiation exposure parameters of dose-rate and total dose in relation to associated health risks was examined in dogs. At a dose-rate of 75, 128, and 263 mGy/d the incidence of acute lymphohematopoietic suppression (aplastic anemia) and associated septic complications was 73%, 87%, and 100%, respectively, and it increased in dose-dependent manner. By contrast, at dose-rates below 75 mGy/d, late cancers contributed significantly to the death of relatively long-lived animals, whose mean survival time was 1800 days. Myeloproliferative disease (MPD), mainly myeloid leukemia, was the dominant pathology seen at the higher daily dose-rates (18.8-75 mGy/d). When daily exposure was carried out continuously, the incidence of MPD was quite high. It should be noted that the induction radiation-induced MPD in this study was highly significant, because spontaneous MPD is exceedingly rare in the dog. However, when the daily dose-rate was reduced further or exposure was discontinued, the incidence of MPD declined significantly. At these lower dose-rates, solid tumors contributed heavily to the life-shortening effects of chronic irradiation. The induction and progression of these survival-compromising, late forms of pathology appeared to be driven by the degree of hematopoietic suppression that occurred early during the exposure phase, and in turn by the capacity of hematopoietic system to repair itself, recover, and to accommodate under chronic radiation stress. (K.H.)

Performance evaluation of a stack cooling system using CO{sub 2} air conditioner in fuel cell vehicles

Energy Technology Data Exchange (ETDEWEB)

Kim, Sung Chul; Won, Jong Phil [Thermal Management Research Center, Korea Automotive Technology Institute, Chungnam 330-912 (Korea); Park, Yong Sun; Lim, Tae Won [Corporate Research and Development Division, Hyundai-Kia Motors, Gyeonggi 449-912 (Korea); Kim, Min Soo [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744 (Korea)

2009-01-15

A relation between the heat release from a fuel cell stack and an air conditioning system's performance was investigated. The air conditioning system installed in a fuel cell vehicle can be used for stack cooling when additional stack heat release is required over a fixed radiator capacity during high vehicle power generation. This study investigated the performance of a stack cooling system using CO{sub 2} air conditioner at various operating conditions. Also, the heat releasing effectiveness and mutual interference were analyzed and compared with those for the conventional radiator cooling system with/without cabin cooling. When the radiator coolant inlet temperature and flow rate were 65 C and 80 L/min, respectively, for the outdoor air inlet speed of 5 m/s, the heat release of the stack cooling system with the aid of CO{sub 2} air conditioner increased up to 36% more than that of the conventional radiator cooling system with cabin cooling. Furthermore, this increased by 7% versus the case without cabin cooling. (author)

Solar thermal heating and cooling. A bibliography with abstracts

Science.gov (United States)

Arenson, M.

1979-01-01

This bibliographic series cites and abstracts the literature and technical papers on the heating and cooling of buildings with solar thermal energy. Over 650 citations are arranged in the following categories: space heating and cooling systems; space heating and cooling models; building energy conservation; architectural considerations, thermal load computations; thermal load measurements, domestic hot water, solar and atmospheric radiation, swimming pools; and economics.

The Application of PVDF in Converter Cooling Pipeline

Science.gov (United States)

Geng, Man; Lu, Zhimin

2017-11-01

The structure, mechanical property, thermodynamics property, electrical aspects, radiation property and chemical property were introduced, and PVDF could satisfy the requirement of converter cooling pipe. PVDF department and pipe of distribution pipeline of converter cooling system in Debao HVDC project are used to introduce the molding process of PVDF.

Potentialities of a new sigma(+)-sigma(-)laser configuration for radiative cooling and trapping

Energy Technology Data Exchange (ETDEWEB)

Dalibard, J; Reynaud, S; Cohen-Tannoudji, C

1984-11-28

In the process of cooling and trapping neutral atoms, a new laser configuration is investigated which consists of two counterpropagating laser beams with orthogonal sigma(+) and sigma(-)polarizations. It is shown that such a configuration looks more promising than an ordinary standing wave (where the two counterpropagating waves have the same polarization), and this result is explained as being due to angular momentum conservation which prevents any coherent redistribution of photons between the two waves. The present conclusions are based on a quantitative calculation of the various parameters (potential depth, friction coefficient, diffusion coefficient) describing the mean value and the fluctuations of the radiative forces experienced, in such a laser configuration, by an atom with a J 0 ground state and a J 1 excited state. 30 references.

Light Optics for Optical Stochastic Cooling

Energy Technology Data Exchange (ETDEWEB)

Andorf, Matthew [NICADD, DeKalb; Lebedev, Valeri [Fermilab; Piot, Philippe [NICADD, DeKalb; Ruan, Jinhao [Fermilab

2016-06-01

In Optical Stochastic Cooling (OSC) radiation generated by a particle in a "pickup" undulator is amplified and transported to a downstream "kicker" undulator where it interacts with the same particle which radiated it. Fermilab plans to carry out both passive (no optical amplifier) and active (optical amplifier) tests of OSC at the Integrable Optics Test Accelerator (IOTA) currently in construction*. The performace of the optical system is analyzed with simulations in Synchrotron Radiation Workshop (SRW) accounting for the specific temporal and spectral properties of undulator radiation and being augmented to include dispersion of lens material.

Variable cooling circuit for thermoelectric generator and engine and method of control

Science.gov (United States)

Prior, Gregory P

2012-10-30

An apparatus is provided that includes an engine, an exhaust system, and a thermoelectric generator (TEG) operatively connected to the exhaust system and configured to allow exhaust gas flow therethrough. A first radiator is operatively connected to the engine. An openable and closable engine valve is configured to open to permit coolant to circulate through the engine and the first radiator when coolant temperature is greater than a predetermined minimum coolant temperature. A first and a second valve are controllable to route cooling fluid from the TEG to the engine through coolant passages under a first set of operating conditions to establish a first cooling circuit, and from the TEG to a second radiator through at least some other coolant passages under a second set of operating conditions to establish a second cooling circuit. A method of controlling a cooling circuit is also provided.

Performance Evaluation of an In-Wheel Motor Cooling System in an Electric Vehicle/Hybrid Electric Vehicle

Directory of Open Access Journals (Sweden)

Dong Hyun Lim

2014-02-01

Full Text Available High power and miniaturization of motors in an in-wheel drive system, which is installed inside the wheels of a vehicle, are required for directly driving the wheels. In addition, an efficient cooling system is required to ensure high driving performance and durability. This study experimentally evaluated the heat dissipation performance of a 35-kW-class large-capacity in-wheel motor equipped with an internal-circulation-type oil-cooling system that exhibits high cooling performance and can be easily miniaturized to this motor. Temperatures of the coil and stator core of cooling systems with and without a radiator were measured in real time under in-wheel motor driving conditions. It was found that operating the cooling system at a continuous-rating maximum speed without the radiator was difficult. We confirmed that under continuous-rating base speed and continuous-rating maximum speed driving conditions, the cooling system with the radiator showed thermally stable operation. Furthermore, under maximum-rating base speed and maximum-rating maximum speed driving conditions, the cooling system with the radiator provided additional driving times of approximately 22 s and 2 s, respectively.

The effect of water vapor in the reactor cavity in a MHTGR [Modular High Temperature Gas Cooled Reactor] on the radiation heat transfer

International Nuclear Information System (INIS)

Cappiello, M.W.

1991-01-01

Analyses have been completed to determine the effect of the presence of water vapor in the reactor cavity in a modular high temperature gas cooled reactor on the predicted radiation heat transfer from the vessel wall to the reactor cavity cooling system. The analysis involves the radiation heat transfer between two parallel plates with an absorbing and emitting medium present. Because the absorption in the water vapor is spectrally dependent, the solution is difficult even for simple geometries. A computer code was written to solve the problem using the Monte Carlo method. The code was validated against closed form solutions, and shows excellent agreement. In the analysis of the reactor problem, the results show that the reduction in heat transfer, and the consequent increase in the vessel wall temperature, can be significant. This effect can be cast in terms of a reduction in the wall surface emissivities from 0.8 to 0.59. Because of the insulating effect of the water vapor, increasing the gap distance between the vessel wall and the cooling system will cause the vessel wall temperature to increase further. Care should be taken in the design of the facility to minimize the gap distance and keep temperature increase within allowable limits. 3 refs., 6 figs., 4 tabs

Simulations of floor cooling system capacity

International Nuclear Information System (INIS)

Odyjas, Andrzej; Górka, Andrzej

2013-01-01

Floor cooling system capacity depends on its physical and operative parameters. Using numerical simulations, it appears that cooling capacity of the system largely depends on the type of cooling loads occurring in the room. In the case of convective cooling loads capacity of the system is small. However, when radiation flux falls directly on the floor the system significantly increases productivity. The article describes the results of numerical simulations which allow to determine system capacity in steady thermal conditions, depending on the type of physical parameters of the system and the type of cooling load occurring in the room. Moreover, the paper sets out the limits of system capacity while maintaining a minimum temperature of the floor surface equal to 20 °C. The results are helpful for designing system capacity in different type of cooling loads and show maximum system capacity in acceptable thermal comfort condition. -- Highlights: ► We have developed numerical model for simulation of floor cooling system. ► We have described floor system capacity depending on its physical parameters. ► We have described floor system capacity depending on type of cooling loads. ► The most important in the obtained cooling capacities is the type of cooling loads. ► The paper sets out the possible maximum cooling floor system capacity

On the determination of the overall heat transmission coefficient and soil heat flux for a fog cooled, naturally ventilated greenhouse: Analysis of radiation and convection heat transfer

International Nuclear Information System (INIS)

Abdel-Ghany, Ahmed M.; Kozai, Toyoki

2006-01-01

A physical model for analyzing the radiative and convective heat transfer in a fog cooled, naturally ventilated greenhouse was developed for estimating the overall heat transmission coefficient based on the conduction, convection and thermal radiation heat transfer coefficients and for predicting the soil heat flux. The contribution of the water vapor of the inside air to the emission and absorption of thermal radiation was determined. Measurements of the outside and inside greenhouse environments to be used in the analysis were conducted around solar noon (12:19-13:00) on a hot sunny day to provide the maximum solar radiation transmission into the greenhouse. The net solar radiation flux measured at the greenhouse floor showed a reasonable agreement with the predicted value. The net fluxes were estimated around noon. The average net radiation (solar and thermal) at the soil surface was 220.0 W m -2 , the average soil heat flux was 155.0 W m -2 and the average contribution of the water vapor of the inside air to the thermal radiation was 22.0 W m -2 . The average overall heat transmission coefficient was 4.0 W m -2 C -1 and was in the range between 3.0 W m -2 C -1 and 6.0 W m -2 C -1 under the different hot summer conditions between the inside and outside of the naturally ventilated, fog cooled greenhouse

Solar cooling systems. Classification and energetic evaluation; Solare Kuehlsysteme. Klassifizierung und energetische Bewertung

Energy Technology Data Exchange (ETDEWEB)

Hennig, Jakob [Technische Univ. Bergakademie Freiberg (Germany); Hafner, Armin [SINTEF Energy Research, Trondheim (Norway); Eikevik, Trygve M. [NTNU, Trondheim (Norway)

2012-07-01

The investigation of alternative, sustainable concepts for cold production is worthwhile in times of increasing energy demand for cooling and air conditioning applications. Energy sources such as solar radiation can help to reduce the burden on the environment and energy networks. Solar electricity from photovoltaic cells or solar power from solar collectors can be used in refrigerating equipment (such as cold vapor compression chiller, absorption chiller, adsorption chillers, open systems, thermo-mechanical systems or ejector-based systems) are fed in order to produce the desired coldness. In many cases, the temporal coincidence of radiation supply and cooling requirements makes the solar cooling to a promising concept, especially at sites with a high solar radiation, large cooling demand, high energy prices, or insufficient access to public power grids. A model-based investigation of different solar cooling systems with an equivalent cooling capacity was carried out. The results show that the performance potential strongly depends on the selected technology and the site of the system. A balanced daily energy balance can be achieved with an appropriately dimensioned solar power plant with cooling concept. Depending on the system and interpretation, primary energy savings or a primary energy overhead can be achieved within a year in comparison to a conventional system.

Effects of total integrated solar radiation on radial fruit cracking in tomato [Lycopersicon esculentum] cultivation under rain shelter in cool uplands

International Nuclear Information System (INIS)

Suzuki, T.; Yanase, S.; Enya, T.; Shimazu, T.; Tanaka, I.

2007-01-01

This study investigated the cause of radial fruit cracking in tomato cultivation under rain shelter in the cool uplands in Gifu Prefecture. The effect of total integrated radiation using two types of training methods was determined over a three-year period. The percentage of refused radial fruit cracking associated with increased total integrated solar radiation from the young fruit stage to the mature green stage. Fruit cracking occurred in the training method which foliage and fruits received a large amount of light-interception. Also, as for fruits that undergo vigorous enlargement, the frequency of the radial fruit cracking increased

Anti-diffusive radiation flow in the cooling layer of a radiating shock

International Nuclear Information System (INIS)

McClarren, Ryan G.; Paul Drake, R.

2010-01-01

This paper shows that for systems with optically thin, hot layers, such as those that occur in radiating shocks, radiation will flow uphill: radiation will flow from low to high radiation energy density. These are systems in which the angular distribution of the radiation intensity changes rapidly in space, and in which the radiation in some region has a pancaked structure, whose effect on the mean intensity will be much larger than the effect on the scalar radiation pressure. The salient feature of the solution to the radiative transfer equation in these circumstances is that the gradient of the radiation energy density is in the same direction as the radiation flux, i.e. radiation energy is flowing uphill. Such an anti-diffusive flow of energy cannot be captured by a model where the spatial variation of the Eddington factor is not accounted for, as in flux-limited diffusion models or the P 1 equations. The qualitative difference between the two models leads to a monotonic mean intensity for the diffusion model whereas the transport mean intensity has a global maximum in the hot layer. Mathematical analysis shows that the discrepancy between the diffusion model and the transport solution is due to an approximation of exponential integrals using a simple exponential.

Conductive cooling of high-power RIB targets

International Nuclear Information System (INIS)

Talbert, W.L.; Drake, D.M.; Wilson, M.T.; Lenz, J.W.; Hsu, H.-H.

2002-01-01

A short review is presented of target cooling approaches suggested for targets irradiated by intense high-energy proton beams to produce radioactive species for use in a broad range of physics studies. This work reports on conductive cooling approaches for operation at temperatures lower than effective for radiative cooling. The possibilities for conductive cooling are discussed, and a prototype test target is described. This target was constructed for an experiment, designed to validate the numerical analysis approaches, at the TRIUMF/ISAC facility. Fabrication issues and the results of the experiment are presented, followed by a discussion of the implications of the experiment outcome for future development of targets to produce intense beams of radioactive ions

Newton's law of cooling revisited

International Nuclear Information System (INIS)

Vollmer, M

2009-01-01

The cooling of objects is often described by a law, attributed to Newton, which states that the temperature difference of a cooling body with respect to the surroundings decreases exponentially with time. Such behaviour has been observed for many laboratory experiments, which led to a wide acceptance of this approach. However, the heat transfer from any object to its surrounding is not only due to conduction and convection but also due to radiation. The latter does not vary linearly with temperature difference, which leads to deviations from Newton's law. This paper presents a theoretical analysis of the cooling of objects with a small Biot number. It is shown that Newton's law of cooling, i.e. simple exponential behaviour, is mostly valid if temperature differences are below a certain threshold which depends on the experimental conditions. For any larger temperature differences appreciable deviations occur which need the complete nonlinear treatment. This is demonstrated by results of some laboratory experiments which use IR imaging to measure surface temperatures of solid cooling objects with temperature differences of up to 300 K.

Modulation by Blood-cooling and Blood Flow-promoting Herbs to the expression of TNF-α and bFGF in radiation induced lung damage of rats

International Nuclear Information System (INIS)

Yang Minghui; Zang Qian; Dou Yongqi; Feng Linchun

2007-01-01

Objective: To observe the modulation by Blood-cooling and Blood Flow-promoting Herbs to expressions of tumor necrosis factor α (TNF-α) and basic fibroblast growth factors (bFGF) in radiation-induced lung injury of rats at different radiation times, and explore the mechanism of prevention and curative effect of the herbs on radiation lung injury. Methods: 160 wistar rats were randomly allocated into irradiation group, treatment group, herb-fracture group and control group. The first two groups were irradiated to right hemithorax with a dose of 30 Gy/10 fraction/5 weeks. Animals were sacrificed at weeks 3,5,8,12 and 26 post irradiation. The level of immunoreactivity of cytokine TNF-α and bFGF was evaluated. Results: The acute radiation-induced pneumonia occurred at weeks 3 and was most serious at weeks 5 and pulmonary fibrosis was remarkable at the late phase in irradiation group. The pneumonia and fibrosis of treatment group were lighter than that of irradiation group. Expressions of TNF-α and bFGF reached their peaks at weeks 5 and 26 of respectively. The expressions in treatment group was significantly lower than that the irradiation group( P<0.01). Conclusions: Blood-cooling and Blood Flow-promoting Herbs can prevent and treat the radiation-reduced lung injury by restraining the expression of TNF-α and bFGF. (authors)

Occupational radiation exposure at light water cooled power reactors. Annual report, 1977

International Nuclear Information System (INIS)

Peck, L.J.

1979-04-01

This report presents an updated compilation of occupational radiation exposures at commercial light water cooled nuclear power reactors (LWRs) for the years 1969 through 1977. The information contained in this document was derived from reports submitted to the United States Nuclear Regulatory Commission in accordance with requirements of individual plant Technical Specifications, and in accordance with Part 20.407 of Title 10, Chapter 1, Code of Federal Regulations (10 CFR Part 20.407). An additional 4 LWRs completed a full calendar year of commercial operation for the first time in 1977. This report now encompasses data from 57 commercially operating U.S. nuclear power plants. The number of personnel monitored at LWRs increased approximately 10% in 1977, and the average collective dose to personnel (man-rems per reactor-year) increased 14% over the 1976 average. The average number of personnel receiving measurable exposure per reactor increased 11%, and the average exposure per individual in 1977 was 0.8 rem per person

Passive cooling containment study

International Nuclear Information System (INIS)

Shin, J.J.; Iotti, R.C.; Wright, R.F.

1993-01-01

Pressure and temperature transients of nuclear reactor containment following postulated loss of coolant accident with a coincident station blackout due to total loss of all alternating current power are studied analytically and experimentally for the full scale NPR (New Production Reactor). All the reactor and containment cooling under this condition would rely on the passive cooling system which removes reactor decay heat and provides emergency core and containment cooling. Containment passive cooling for this study takes place in the annulus between containment steel shell and concrete shield building by natural convection air flow and thermal radiation. Various heat transfer coefficients inside annular air space were investigated by running the modified CONTEMPT code CONTEMPT-NPR. In order to verify proper heat transfer coefficient, temperature, heat flux, and velocity profiles were measured inside annular air space of the test facility which is a 24 foot (7.3m) high, steam heated inner cylinder of three foot (.91m) diameter and five and half foot (1.7m) diameter outer cylinder. Comparison of CONTEMPT-NPR and WGOTHIC was done for reduced scale NPR

Investigation of cooling methods and thickness considerations in the filter/window assembly for synchrotron radiation beamlines

International Nuclear Information System (INIS)

Wang, Z.; Kuzay, T.M.; Hahn, U.

1993-01-01

Synchrotron x-ray windows are vacuum separators and are usually made of thin beryllium metal. Filters are provided upstream to absorb the soft x-rays so that the window can be protected from overheating, which could result in failure. The filters are made of thin carbon products or sometimes beryllium, the same material as the window. When the synchrotron x-rays pass through a filter or window, part of the photons will be absorbed by the filter or window. The absorbed photons cause heat to build up within the filter or window. Successful filter and window designs should effectively dissipate the heat generated by the absorbed photons and guarantee the safety of the filter and window. The cooling methods typically used in a filter or window design are conduction and radiation cooling or a combination of the two. The different cooling methods were first examined with regard to efficiency and effectiveness in different temperature ranges. Analysis results are presented for temperature distribution and corresponding thermal stresses in the filter and window. Another important issue to be resolved in designing a filter/window assembly is how to select the thickness of the filters and windows. This paper focuses on the criteria for choosing the thickness of a filter: whether it is better to use a few thick filters or a series of thin ones; how to determine the minimum/maximum thickness; and the difference in thickness considerations for the window versus the filter. Numerical investigations are presented

Concept of a staged FEL enabled by fast synchrotron radiation cooling of laser-plasma accelerated beam by solenoidal magnetic fields in plasma bubble

Science.gov (United States)

Seryi, Andrei; Lesz, Zsolt; Andreev, Alexander; Konoplev, Ivan

2017-03-01

A novel method for generating GigaGauss solenoidal fields in a laser-plasma bubble, using screw-shaped laser pulses, has been recently presented. Such magnetic fields enable fast synchrotron radiation cooling of the beam emittance of laser-plasma accelerated leptons. This recent finding opens a novel approach for design of laser-plasma FELs or colliders, where the acceleration stages are interleaved with laser-plasma emittance cooling stages. In this concept paper, we present an outline of what a staged plasma-acceleration FEL could look like, and discuss further studies needed to investigate the feasibility of the concept in detail.

THE EFFECT OF COOLING ON PARTICLE TRAJECTORIES AND ACCELERATION IN RELATIVISTIC MAGNETIC RECONNECTION

Energy Technology Data Exchange (ETDEWEB)

Kagan, Daniel; Nakar, Ehud [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Piran, Tsvi, E-mail: daniel.kagan@mail.huji.ac.il [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)

2016-12-20

The maximum synchrotron burnoff limit of 160 MeV represents a fundamental limit to radiation resulting from electromagnetic particle acceleration in one-zone ideal plasmas. In magnetic reconnection, however, particle acceleration and radiation are decoupled because the electric field is larger than the magnetic field in the diffusion region. We carry out two-dimensional particle-in-cell simulations to determine the extent to which magnetic reconnection can produce synchrotron radiation above the burnoff limit. We use the test particle comparison (TPC) method to isolate the effects of cooling by comparing the trajectories and acceleration efficiencies of test particles incident on such a reconnection region with and without cooling them. We find that the cooled and uncooled particle trajectories are typically similar during acceleration in the reconnection region, and derive an effective limit on particle acceleration that is inversely proportional to the average magnetic field experienced by the particle during acceleration. Using the calculated distribution of this average magnetic field as a function of uncooled final particle energy, we find analytically that cooling does not affect power-law particle energy spectra except at energies far above the synchrotron burnoff limit. Finally, we compare fully cooled and uncooled simulations of reconnection, confirming that the synchrotron burnoff limit does not produce a cutoff in the particle energy spectrum. Our results indicate that the TPC method accurately predicts the effects of cooling on particle acceleration in relativistic reconnection, and that, even far above the burnoff limit, the synchrotron energy of radiation produced in reconnection is not limited by cooling.

THE EFFECT OF COOLING ON PARTICLE TRAJECTORIES AND ACCELERATION IN RELATIVISTIC MAGNETIC RECONNECTION

International Nuclear Information System (INIS)

Kagan, Daniel; Nakar, Ehud; Piran, Tsvi

2016-01-01

The maximum synchrotron burnoff limit of 160 MeV represents a fundamental limit to radiation resulting from electromagnetic particle acceleration in one-zone ideal plasmas. In magnetic reconnection, however, particle acceleration and radiation are decoupled because the electric field is larger than the magnetic field in the diffusion region. We carry out two-dimensional particle-in-cell simulations to determine the extent to which magnetic reconnection can produce synchrotron radiation above the burnoff limit. We use the test particle comparison (TPC) method to isolate the effects of cooling by comparing the trajectories and acceleration efficiencies of test particles incident on such a reconnection region with and without cooling them. We find that the cooled and uncooled particle trajectories are typically similar during acceleration in the reconnection region, and derive an effective limit on particle acceleration that is inversely proportional to the average magnetic field experienced by the particle during acceleration. Using the calculated distribution of this average magnetic field as a function of uncooled final particle energy, we find analytically that cooling does not affect power-law particle energy spectra except at energies far above the synchrotron burnoff limit. Finally, we compare fully cooled and uncooled simulations of reconnection, confirming that the synchrotron burnoff limit does not produce a cutoff in the particle energy spectrum. Our results indicate that the TPC method accurately predicts the effects of cooling on particle acceleration in relativistic reconnection, and that, even far above the burnoff limit, the synchrotron energy of radiation produced in reconnection is not limited by cooling.

Effect mechanism of air deflectors on the cooling performance of dry cooling tower with vertical delta radiators under crosswind

International Nuclear Information System (INIS)

Zhao, Yuanbin; Long, Guoqing; Sun, Fengzhong; Li, Yan; Zhang, Cuijiao; Liu, Jiabin

2015-01-01

Highlights: • A 3D numerical model was set for NDDCTV to study the effect of air deflectors. • The air deflectors improve the tower performance by 1.375 °C at u c = 6 m/s for a case. • The air deflectors reduce the air inflow deviation angle θ d at most delta entries. • The reduced θ d can improve the cooling performance of former deteriorated columns. • Both the radial inflow air velocity and θ d impact the cooling performance of delta. - Abstract: To study the effect mechanism of air deflectors on dry cooling tower, a three dimensional numerical model was established, with full consideration of the delta structure. The accuracy and credibility of dry cooling tower numerical model were validated. By numerical model, the average air static pressure and the average radial inflow air velocity were computed and analyzed at delta air entry, sector air entry and exit faces. By the air inflow deviation angle θ d , the effect of air deflectors on the aerodynamic field around tower was analyzed. The water exit temperatures of θ −1 columns, θ +2 columns and cooling sectors were also presented to clarify the effect of air deflectors. It was found that the air deflectors improved the aerodynamic field around cooling columns. The reduced air inflow deviation degree at delta entry improved the cooling performance of deteriorated columns. Referring to the radial inflow air velocity u ra and the air inflow deviation degree at delta entry, the effect mechanism of air deflectors are clarified under crosswind

Optimal control and performance test of solar-assisted cooling system

KAUST Repository

Huang, B.J.; Yen, C.W.; Wu, J.H.; Liu, J.H.; Hsu, H.Y.; Petrenko, V.O.; Chang, J.M.; Lu, C.W.

2010-01-01

temperature. This will make the SACH always produce cooling effect even at lower solar radiation periods while the ejector performs at off-design conditions. The energy saving of A/C is experimentally shown 50-70% due to the cooling performance of ECS

Final Cooling for a Muon Collider

Energy Technology Data Exchange (ETDEWEB)

Acosta Castillo, John Gabriel [Univ. of Mississippi, Oxford, MS (United States)

2017-05-01

To explore the new energy frontier, a new generation of particle accelerators is needed. Muon colliders are a promising alternative, if muon cooling can be made to work. Muons are 200 times heavier than electrons, so they produce less synchrotron radiation, and they behave like point particles. However, they have a short lifetime of 2.2 $\\mathrm{\\mu s}$ and the beam is more difficult to cool than an electron beam. The Muon Accelerator Program (MAP) was created to develop concepts and technologies required by a muon collider. An important effort has been made in the program to design and optimize a muon beam cooling system. The goal is to achieve the small beam emittance required by a muon collider. This work explores a final ionization cooling system using magnetic quadrupole lattices with a low enough $\\beta^{\\star} $ region to cool the beam to the required limit with available low Z absorbers.

Wave-optics modeling of the optical-transport line for passive optical stochastic cooling

Science.gov (United States)

Andorf, M. B.; Lebedev, V. A.; Piot, P.; Ruan, J.

2018-03-01

Optical stochastic cooling (OSC) is expected to enable fast cooling of dense particle beams. Transition from microwave to optical frequencies enables an achievement of stochastic cooling rates which are orders of magnitude higher than ones achievable with the classical microwave based stochastic cooling systems. A subsystemcritical to the OSC scheme is the focusing optics used to image radiation from the upstream "pickup" undulator to the downstream "kicker" undulator. In this paper, we present simulation results using wave-optics calculation carried out with the SYNCHROTRON RADIATION WORKSHOP (SRW). Our simulations are performed in support to a proof-of-principle experiment planned at the Integrable Optics Test Accelerator (IOTA) at Fermilab. The calculations provide an estimate of the energy kick received by a 100-MeV electron as it propagates in the kicker undulator and interacts with the electromagnetic pulse it radiated at an earlier time while traveling through the pickup undulator.

Evaluation of radiation heat transfer in porous medial: Application for a pebble bed modular reactor cooled by CO2 gas

Directory of Open Access Journals (Sweden)

Sidi-Ali Kamel

2013-01-01

Full Text Available This work analyses the contribution of radiation heat transfer in the cooling of a pebble bed modular reactor. The mathematical model, developed for a porous medium, is based on a set of equations applied to an annular geometry. Previous major works dealing with the subject have considered the forced convection mode and often did not take into account the radiation heat transfer. In this work, only free convection and radiation heat transfer are considered. This can occur during the removal of residual heat after shutdown or during an emergency situation. In order to derive the governing equations of radiation heat transfer, a steady-state in an isotropic and emissive porous medium (CO2 is considered. The obtained system of equations is written in a dimensionless form and then solved. In order to evaluate the effect of radiation heat transfer on the total heat removed, an analytical method for solving the system of equations is used. The results allow quantifying both radiation and free convection heat transfer. For the studied situation, they show that, in a pebble bed modular reactor, more than 70% of heat is removed by radiation heat transfer when CO2 is used as the coolant gas.

Cooling out the radiation damage on the XMM-Newton EPIC MOS CCDs

Energy Technology Data Exchange (ETDEWEB)

Abbey, A.F. E-mail: afa@star.le.ac.uk; Bennie, P.J.; Turner, M.J.L.; Altieri, B.; Rives, S

2003-11-01

The X-ray astronomy satellite XMM-Newton has been in an orbit taking it through the trapped radiation belts and direct solar proton flux during the peak of the current solar cycle for over two and a half years. The MOS CCD detectors (E2 V CCD22's) have degraded in charge transfer efficiency (CTE) as a result of damage created by high energy protons. Corrections for CTE in ground software have managed to restore most of the energy loss generated by the trapping sites, but the detector energy resolution has widened due to imperfect correction methods and the statistical noise generated by charge trapping. The detectors have been at -100 deg. C since launch, and they are qualified to operate down to -130 deg. C. Similar CCDs have been irradiated on the ground with 10 MeV protons and it was believed that the devices in orbit, although irradiated by much lower fluxes for longer times should exhibit the same improved CTE at lower temperatures. There was also concern that contrary to test devices on the ground, the devices in orbit had been almost continually cold for over 2 years and many bright pixels had developed giving a signal even at -100 deg. C, due possibly to radiation and the impact of micro-meteoroids. Cooling the CCDs in XMM to -120 deg. C demonstrated the expected improvement, and we intend to run both MOS cameras at the new temperature later in the year.

Los Alamos NEP research in advanced plasma thrusters

Science.gov (United States)

Schoenberg, Kurt; Gerwin, Richard

1991-01-01

Research was initiated in advanced plasma thrusters that capitalizes on lab capabilities in plasma science and technology. The goal of the program was to examine the scaling issues of magnetoplasmadynamic (MPD) thruster performance in support of NASA's MPD thruster development program. The objective was to address multi-megawatt, large scale, quasi-steady state MPD thruster performance. Results to date include a new quasi-steady state operating regime which was obtained at space exploration initiative relevant power levels, that enables direct coaxial gun-MPD comparisons of thruster physics and performance. The radiative losses are neglible. Operation with an applied axial magnetic field shows the same operational stability and exhaust plume uniformity benefits seen in MPD thrusters. Observed gun impedance is in close agreement with the magnetic Bernoulli model predictions. Spatial and temporal measurements of magnetic field, electric field, plasma density, electron temperature, and ion/neutral energy distribution are underway. Model applications to advanced mission logistics are also underway.

Validation of CFD modeling for VGM loss-of-forced-cooling accidents

International Nuclear Information System (INIS)

Wysocki, Aaron; Ahmed, Bobby; Charmeau, Anne; Anghaie, Samim

2009-01-01

Heat transfer and fluid flow in the VGM reactor cavity cooling system (RCCS) was modeled using Computational Fluid Dynamics (CFD). The VGM is a Russian modular-type high temperature helium-cooled reactor. In the reactor cavity, heat is removed from the pressure vessel wall through natural convection and radiative heat transfer to water-cooled vertical pipes lining the outer cavity concrete. The RCCS heat removal capability under normal operation and accident scenarios needs to be assessed. The purpose of the present study is to validate the use of CFD to model heat transfer in the VGM RCCS. Calculations were based on a benchmark problem which defines a two-dimensional temperature distribution on the pressure vessel outer wall for both Depressurized and Pressurized Loss-of-Forced Cooling events. A two-dimensional axisymmetric model was developed to determine the best numerical modeling approach. A grid sensitivity study for the air region showed that a 20 mm mesh size with a boundary layer giving a maximum y+ of 2.0 was optimal. Sensitivity analyses determined that the discrete ordinates radiative model, the k-omega turbulence model, and the ideal gas law gave the best combination for capturing radiation and natural circulation in the air cavity. A maximum RCCS pipe wall temperature of 62degC located 6 m from the top of the cavity was predicted. The model showed good agreement with previous results for both Pressurized and Depressurized Loss-of-Forced-Cooling accidents based on RCCS coolant outlet temperature, relative contributions of radiative and convective heat transfer, and RCCS heat load profiles. (author)

Wave-Optics Modeling of the Optical-Transport Line for Passive Optical Stochastic Cooling

Energy Technology Data Exchange (ETDEWEB)

Andorf, M. B. [NICADD, DeKalb; Lebedev, V. A. [Fermilab; Piot, P. [Fermilab; Ruan, J. [Fermilab

2018-03-01

Optical stochastic cooling (OSC) is expected to enable fast cooling of dense particle beams. Transition from microwave to optical frequencies enables an achievement of stochastic cooling rates which are orders of magnitude higher than ones achievable with the classical microwave based stochastic cooling systems. A subsytem critical to the OSC scheme is the focusing optics used to image radiation from the upstream "pickup" undulator to the downstream "kicker" undulator. In this paper, we present simulation results using wave-optics calculation carried out with the {\\sc Synchrotron Radiation Workshop} (SRW). Our simulations are performed in support to a proof-of-principle experiment planned at the Integrable Optics Test Accelerator (IOTA) at Fermilab. The calculations provide an estimate of the energy kick received by a 100-MeV electron as it propagates in the kicker undulator and interacts with the electromagnetic pulse it radiated at an earlier time while traveling through the pickup undulator.

White-light laser cooling of ions in a storage ring

International Nuclear Information System (INIS)

Calabrese, R.; Guidi, V.; Lenisa, P.; Grimm, R.; Miesner, H.J.; Mariotti, E.; Siena Univ.; Moi, L.; Siena Univ.

1996-01-01

We propose the use of a white laser for laser cooling of ions in a storage ring. The use of a broad-band laser provides a radiation pressure force with wide velocity capture range and high magnitude, which is promising to improve the performance of both longitudinal and indirect transverse cooling. This wide-range force could also be suitable for direct transverse cooling of low-density beams. (orig.)

Final muon cooling for a muon collider

Science.gov (United States)

Acosta Castillo, John Gabriel

To explore the new energy frontier, a new generation of particle accelerators is needed. Muon colliders are a promising alternative if muon cooling can be made to work. Muons are 200 times heavier than electrons, so they produce less synchrotron radiation, and they behave like point particles. However, they have a short lifetime of 2.2 mus and the beam is more difficult to cool than an electron beam. The Muon Accelerator Program (MAP) was created to develop concepts and technologies required by a muon collider. An important effort has been made in the program to design and optimize a muon beam cooling system. The goal is to achieve the small beam emittance required by a muon collider. This work explores a final ionization cooling system using magnetic quadrupole lattices with a low enough beta* region to cool the beam to the required limit with available low Z absorbers.

Radiative cooling of hot Cn− and CnH− molecules

International Nuclear Information System (INIS)

Kaminska, M; Nascimento, R F; Stockett, M H; Anderson, E K; Thomas, R D; Gatchell, M; Zettergren, H; Schmidt, H T; Cederquist, H; Delaunay, R; Vizcaino, V; Rousseau, P; Adoui, L; Huber, B A; Hansen, K

2015-01-01

We have measured the rates of neutrals produced from 10 keV C n − or C n H − (n=2, 4, 6, 8, and 10) ion beams stored in one of DESIREE's 14 K storage rings. For n=4, 6, and 8 we observe marked differences between C n − and C n H − cooling rates as inverse internal conversion [cf. S. Martin et al (2013) Phys. Rev. Lett. 110, 063003] processes are effective for the C n − ions only. Knowledge of the cooling rates of these ions are important for estimates of their formation and destruction rates in cold interstellar environments. (paper)

Prospects for cooling nanomechanical motion by coupling to a superconducting microwave resonator

International Nuclear Information System (INIS)

Teufel, J D; Regal, C A; Lehnert, K W

2008-01-01

Recent theoretical work has shown that radiation pressure effects can in principle cool a mechanical degree of freedom to its ground state. In this paper, we apply this theory to our realization of an optomechanical system in which the motion of mechanical oscillator modulates the resonance frequency of a superconducting microwave circuit. We present experimental data demonstrating the large mechanical quality factors possible with metallic, nanomechanical beams at 20 mK. Further measurements also show damping and cooling effects on the mechanical oscillator due to the microwave radiation field. These data motivate the prospects for employing this dynamical backaction technique to cool a mechanical mode entirely to its quantum ground state.

Experiments on the Recovery of Waste Heat in Cooling Ducts, Special Report

Science.gov (United States)

Silverstein, Abe

1939-01-01

Tests have been conducted in the N.A.C.A. full-scale wind tunnel to investigate the partial recovery of the heat energy which is apparently wasted in the cooling of aircraft engines. The results indicate that if the radiator is located in an expanded duct, a part of the energy lost in cooling is recovered; however, the energy recovery is not of practical importance up to airplane speeds of 400 miles per hour. Throttling of the duct flow occurs with heated radiators and must be considered in designing the duct outlets from data obtained with cold radiators in the ducts.

Laser cooling of a harmonic oscillator's bath with optomechanics

Science.gov (United States)

Xu, Xunnong; Taylor, Jacob

Thermal noise reduction in mechanical systems is a topic both of fundamental interest for studying quantum physics at the macroscopic level and for application of interest, such as building high sensitivity mechanics based sensors. Similar to laser cooling of neutral atoms and trapped ions, the cooling of mechanical motion by radiation pressure can take single mechanical modes to their ground state. Conventional optomechanical cooling is able to introduce additional damping channel to mechanical motion, while keeping its thermal noise at the same level, and as a consequence, the effective temperature of the mechanical mode is lowered. However, the ratio of temperature to quality factor remains roughly constant, preventing dramatic advances in quantum sensing using this approach. Here we propose an efficient scheme for reducing the thermal load on a mechanical resonator while improving its quality factor. The mechanical mode of interest is assumed to be weakly coupled to its heat bath but strongly coupled to a second mechanical mode, which is cooled by radiation pressure coupling to a red detuned cavity field. We also identify a realistic optomechanical design that has the potential to realize this novel cooling scheme. Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, MD 20742, USA.

Controlling the radiative properties of cool black-color coatings pigmented with CuO submicron particles

International Nuclear Information System (INIS)

Gonome, Hiroki; Baneshi, Mehdi; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao

2014-01-01

The objective of this study was to design a pigmented coating with dark appearance that maintains a low temperature while exposed to sunlight. The radiative properties of a black-color coating pigmented with copper oxide (CuO) submicron particles are described. In the present work, the spectral behavior of the CuO-pigmented coating was calculated. The radiative properties of CuO particles were evaluated, and the radiative transfer in the pigmented coating was modeled using the radiation element method by ray emission model (REM 2 ). The coating is made using optimized particles. The reflectivity is measured by spectroscopy and an integrating sphere in the visible (VIS) and near infrared (NIR) regions. By using CuO particles controlled in size, we were able to design a black-color coating with high reflectance in the NIR region. The coating substrate also plays an important role in controlling the reflectance. The NIR reflectance of the coating on a standard white substrate with appropriate coating thickness and volume fraction was much higher than that on a standard black substrate. From the comparison between the experimental and calculated results, we know that more accurate particle size control enables us to achieve better performance. The use of appropriate particles with optimum size, coating thickness and volume fraction on a suitable substrate enables cool and black-color coating against solar irradiation. -- Highlights: • A new approach in designing pigmented coatings was used. • The effects of particles size on both visible and near infrared reflectivities were studied. • The results of numerical calculation were compared with experimental ones for CuO powders

A temperature rise equation for predicting environmental impact and performance of cooling ponds

Energy Technology Data Exchange (ETDEWEB)

Serag-Eldin, M.A. [American Univ. in Cairo, Cairo (Egypt). Dept. of Mechanical Engineering

2009-07-01

Cooling ponds are used to cool the condenser water used in large central air-conditioning systems. However, larger cooling loads can often increase pond surface evaporation rates. A temperature-rise energy equation was developed to predict temperature rises in cooling ponds subjected to heating loads. The equation was designed to reduce the need for detailed meteorological data as well as to determine the required surface area and depth of the pond for any given design criteria. Energy equations in the presence and absence of cooling loads were subtracted from each other to determine increases in pond temperature resulting from the cooling load. The energy equations include solar radiation, radiation exchange with sky and surroundings, heat convection from the surface, evaporative cooling, heat conducted to the walls, and rate of change of water temperature. Results of the study suggested that the environmental impact and performance of the cooling pond is a function of temperature only. It was concluded that with the aid of the calculated flow field and temperature distribution, the method can be used to position sprays in order to produce near-uniform pond temperatures. 10 refs., 12 figs.

RCCS Experiments and Validation for High Temperature Gas-Cooled Reactor

International Nuclear Information System (INIS)

Chang Oh; Cliff Davis; Goon C. Park

2007-01-01

A reactor cavity cooling system (RCCS), an air-cooled helical coil RCCS unit immersed in the water pool, was proposed to overcome the disadvantages of the weak cooling ability of air-cooled RCCS and the complex structure of water-cooled RCCS for the high temperature gas-cooled reactor (HTGR). An experimental apparatus was constructed to investigate the various heat transfer phenomena in the water pool type RCCS, such as the natural convection of air inside the cavity, radiation in the cavity, the natural convection of water in the water pool and the forced convection of air in the cooling pipe. The RCCS experimental results were compared with published correlations. The CFX code was validated using data from the air-cooled portion of the RCCS. The RELAP5 code was validated using measured temperatures from the reactor vessel and cavity walls

Fragmentation inside atomic cooling haloes exposed to Lyman-Werner radiation

Science.gov (United States)

Regan, John A.; Downes, Turlough P.

2018-04-01

Supermassive stars born in pristine environments in the early Universe hold the promise of being the seeds for the supermassive black holes observed as high redshift quasars shortly after the epoch of reionisation. H2 suppression is thought to be crucial in order to negate normal Population III star formation and allow high accretion rates to drive the formation of supermassive stars. Only in the cases where vigorous fragmentation is avoided will a monolithic collapse be successful, giving rise to a single massive central object. We investigate the number of fragmentation sites formed in collapsing atomic cooling haloes subject to various levels of background Lyman-Werner flux. The background Lyman-Werner flux manipulates the chemical properties of the gas in the collapsing halo by destroying H2. We find that only when the collapsing gas cloud shifts from the molecular to the atomic cooling regime is the degree of fragmentation suppressed. In our particular case, we find that this occurs above a critical Lyman-Werner background of J ˜ 10 J21. The important criterion being the transition to the atomic cooling regime rather than the actual value of J, which will vary locally. Once the temperature of the gas exceeds T ≳ 104 K and the gas transitions to atomic line cooling, then vigorous fragmentation is strongly suppressed.

High cloud variations with surface temperature from 2002 to 2015: Contributions to atmospheric radiative cooling rate and precipitation changes

Science.gov (United States)

Liu, Run; Liou, Kuo-Nan; Su, Hui; Gu, Yu; Zhao, Bin; Jiang, Jonathan H.; Liu, Shaw Chen

2017-05-01

The global mean precipitation is largely constrained by atmospheric radiative cooling rates (Qr), which are sensitive to changes in high cloud fraction. We investigate variations of high cloud fraction with surface temperature (Ts) from July 2002 to June 2015 and compute their radiative effects on Qr using the Fu-Liou-Gu plane-parallel radiation model. We find that the tropical mean (30°S-30°N) high cloud fraction decreases with increasing Ts at a rate of about -1.0 ± 0.34% K-1 from 2002 to 2015, which leads to an enhanced atmospheric cooling around 0.86 W m-2 K-1. On the other hand, the northern midlatitudes (30°N-60°N) high cloud fraction increases with surface warming at a rate of 1.85 ± 0.65% K-1 and the near-global mean (60°S-60°N) high cloud fraction shows a statistically insignificant decreasing trend with increasing Ts over the analysis period. Dividing high clouds into cirrus, cirrostratus, and deep convective clouds, we find that cirrus cloud fraction increases with surface warming at a rate of 0.32 ± 0.11% K-1 (0.01 ± 0.17% K-1) for the near-global mean (tropical mean), while cirrostratus and deep convective clouds decrease with surface warming at a rate of -0.02 ± 0.18% K-1 and -0.33 ± 0.18% K-1 for the near-global mean and -0.64 ± 0.23% K-1 and -0.37 ± 0.13% K-1 for the tropical mean, respectively. High cloud fraction response to feedback to Ts accounts for approximately 1.9 ± 0.7% and 16.0 ± 6.1% of the increase in precipitation per unit surface warming over the period of 2002-2015 for the near-global mean and the tropical mean, respectively.

Evaporative cooling in ATLAS - present and future

CERN Document Server

Viehhauser, G; The ATLAS collaboration

2010-01-01

The ATLAS Inner Detector cooling system is the largest evaporative cooling system used in High Energy Physics today. During the installation and commissioning of this system many lessons had to be learned, but the system is now operating reliably, although it does not achieve all original design specifications in all its circuits. We have re-evaluated the requirements for the cooling system, in particular for the evaporation temperature, over the full ATLAS operational lifetime. We find that the critical requirement is for thermal stability at the end of the operation in the high-radiation environment. To predict this we have developed a simple thermal model of the detector modules which yields analytical expressions to evaluate the results of changes in the operating conditions. After a comparison of the revised requirements and the actual present cooling system performance we will discuss various modifications to the system which will be required for future operation. In parallel we are developing a cooling...

Selective covers for natural cooling devices

International Nuclear Information System (INIS)

Addeo, A.; Monza, E.; Peraldo, M.; Bartoli, B.; Coluzzi, B.; Silvestrini, V.; Troise, G.

1978-01-01

Extra-atmospheric space is practically a pure sink of radiation, and can be used as a nonconventional energy source. In previous papers it has been shown that surfaces with an emissivity matched with the atmospheric (8/13)μm ''transparency window'' (natural emitters) interact with cold space when exposed to clear sky at night, and undergo a sizable cooling effect. In this paper, starting from experimental results concerning the diurnal performances of natural emitters, the problem of their interaction with solar radiation is discussed, and the use is proposed of selective covers which shade the emitter from solar radiation, without preventing the interaction with cold space via emission of infra-red radiation. (author)

Experiments on aerosol-induced cooling in the nocturnal boundary layer

Science.gov (United States)

Sreenivas, K.; Singh, D. K.; Vk, P.; Mukund, V.; Subramanian, G.

2012-12-01

In the nocturnal boundary layer (NBL), under calm & clear-sky conditions, radiation is the principal mode of heat transfer & it determines the temperature distribution close to the ground. Radiative processes thus influence the surface energy budget, & play a decisive role in many micro-meteorological processes including the formation of radiation-fog & inversion layer. Here, we report hyper-cooling of air layers close to the ground that has a radiative origin. Resulting vertical temperature distribution has an anomalous profile with an elevated minimum few decimetres above the ground (known as Lifted Temperature Minimum; LTM). Even though the first observation of this type of profile dates back to 1930s, its origin has not been explained till recently. We report field experiments to elucidate effects of emissivity and other physical properties of the ground on the LTM profile. Field observations clearly indicate that LTM-profiles are observed as a rule in the lowest meter of the NBL. We also demonstrate that the air-layer near the ground, rather than the ground itself, leads the post sunset cooling. This fact changes the very nature of the sensible heat-flux boundary condition. A laboratory experimental setup has been developed that can reproduce LTM. Lab-experiments demonstrate that the high cooling rates observed in the field experiments arise from the presence of aerosols & the intensity of cooling is proportional to aerosol concentration (Fig-1). We have also captured penetrative convection cells in the field experiments (Fig-2). Results presented here thus help in parameterizing transport processes in the NBL.

Cooling Effectiveness Measurements for Air Film Cooling of Thermal Barrier Coated Surfaces in a Burner Rig Environment Using Phosphor Thermometry

Science.gov (United States)

Eldridge, Jeffrey I.; Shyam, Vikram; Wroblewski, Adam C.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.

2016-01-01

While the effects of thermal barrier coating (TBC) thermal protection and air film cooling effectiveness are usually studied separately, their contributions to combined cooling effectiveness are interdependent and are not simply additive. Therefore, combined cooling effectiveness must be measured to achieve an optimum balance between TBC thermal protection and air film cooling. In this investigation, surface temperature mapping was performed using recently developed Cr-doped GdAlO3 phosphor thermometry. Measurements were performed in the NASA GRC Mach 0.3 burner rig on a TBC-coated plate using a scaled up cooling hole geometry where both the mainstream hot gas temperature and the blowing ratio were varied. Procedures for surface temperature and cooling effectiveness mapping of the air film-cooled TBC-coated surface are described. Applications are also shown for an engine component in both the burner rig test environment as well as an engine afterburner environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and advantages of this method over infrared thermography as well as the limitations of this method for studying air film cooling are discussed.

Contributions of the Higher Vibrational Levels of Nitric Oxide to the Radiative Cooling of the Thermosphere

Science.gov (United States)

Venkataramani, K.; Yonker, J. D.; Bailey, S. M.

2014-12-01

The 5.3μm emission from the vibrational levels of nitric oxide (NO) and the 15μm emission from CO2 are known to be the dominant sources of cooling in the thermosphere above 100 km. The 5.3μm emission is primarily produced by the radiative de-excitation of NO from its first vibrational level, which in turn is mainly populated by the collisions of NO with atomic oxygen. However, the reaction of atomic nitrogen (N(4S) and N(2D)) with O2 yields vibrationally excited NO with v>1, resulting in a radiative cascade which produces more than one 5.3μm photon per vibrationally excited NO molecule. This chemiluminescence is approximately 20% in magnitude of the emission produced by thermal collisions. These additional sources of the 5.3μm emission are introduced into a one dimensional photochemical model and the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) to assess their variability with latitude and solar activity, and to also understand their effect on the thermospheric energy budget. The results from the models are compared with data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment on-board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, which has been making measurements of the infrared radiative response of the mesosphere and thermosphere to solar inputs since 2002.

Investigations on passive containment cooling

International Nuclear Information System (INIS)

Knebel, J.U.; Cheng, X.; Neitzel, H.J.; Erbacher, F.J.; Hofmann, F.

1997-01-01

The composite containment design for advanced LWRs that has been examined under the PASCO project is a promising design concept for purely passive decay heat removal after a severe accident. The passive cooling processes applied are natural convection and radiative heat transfer. Heat transfer through the latter process removes at an emission coefficient of 0.9 about 50% of the total heat removed via the steel containment, and thus is an essential factor. The heat transferring surfaces must have a high emission coefficient. The sump cooling concept examined under the SUCO project achieves a steady, natural convection-driven flow from the heat source to the heat sink. (orig./CB) [de

Theory of semiconductor laser cooling

Science.gov (United States)

Rupper, Greg

Recently laser cooling of semiconductors has received renewed attention, with the hope that a semiconductor cooler might be able to achieve cryogenic temperatures. In order to study semiconductor laser cooling at cryogenic temperatures, it is crucial that the theory include both the effects of excitons and the electron-hole plasma. In this dissertation, I present a theoretical analysis of laser cooling of bulk GaAs based on a microscopic many-particle theory of absorption and luminescence of a partially ionized electron-hole plasma. This theory has been analyzed from a temperature 10K to 500K. It is shown that at high temperatures (above 300K), cooling can be modeled using older models with a few parameter changes. Below 200K, band filling effects dominate over Auger recombination. Below 30K excitonic effects are essential for laser cooling. In all cases, excitonic effects make cooling easier then predicted by a free carrier model. The initial cooling model is based on the assumption of a homogeneous undoped semiconductor. This model has been systematically modified to include effects that are present in real laser cooling experiments. The following modifications have been performed. (1) Propagation and polariton effects have been included. (2) The effect of p-doping has been included. (n-doping can be modeled in a similar fashion.) (3) In experiments, a passivation layer is required to minimize non-radiative recombination. The passivation results in a npn heterostructure. The effect of the npn heterostructure on cooling has been analyzed. (4) The effect of a Gaussian pump beam was analyzed and (5) Some of the parameters in the cooling model have a large uncertainty. The effect of modifying these parameters has been analyzed. Most of the extensions to the original theory have only had a modest effect on the overall results. However we find that the current passivation technique may not be sufficient to allow cooling. The passivation technique currently used appears

Supernova cooling in a dark matter smog

International Nuclear Information System (INIS)

Zhang, Yue

2014-01-01

A light hidden gauge boson with kinetic mixing with the usual photon is a popular setup in theories of dark matter. The supernova cooling via radiating the hidden boson is known to put an important constraint on the mixing. I consider the possible role dark matter, which under reasonable assumptions naturally exists inside supernova, can play in the cooling picture. Because the interaction between the hidden gauge boson and DM is likely unsuppressed, even a small number of dark matter compared to protons inside the supernova could dramatically shorten the free streaming length of the hidden boson. A picture of a dark matter “smog” inside the supernova, which substantially relaxes the cooling constraint, is discussed in detail

Supernova cooling in a dark matter smog

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yue [Walter Burke Institute for Theoretical Physics, California Institute of Technology, Pasadena, CA 91125 (United States)

2014-11-27

A light hidden gauge boson with kinetic mixing with the usual photon is a popular setup in theories of dark matter. The supernova cooling via radiating the hidden boson is known to put an important constraint on the mixing. I consider the possible role dark matter, which under reasonable assumptions naturally exists inside supernova, can play in the cooling picture. Because the interaction between the hidden gauge boson and DM is likely unsuppressed, even a small number of dark matter compared to protons inside the supernova could dramatically shorten the free streaming length of the hidden boson. A picture of a dark matter “smog” inside the supernova, which substantially relaxes the cooling constraint, is discussed in detail.

The ATLAS IBL CO2 Cooling System

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00237783; The ATLAS collaboration; Zwalinski, L.; Bortolin, C.; Vogt, S.; Godlewski, J.; Crespo-Lopez, O.; Van Overbeek, M.; Blaszcyk, T.

2017-01-01

The ATLAS Pixel detector has been equipped with an extra B-layer in the space obtained by a reduced beam pipe. This new pixel detector called the ATLAS Insertable B-Layer (IBL) is installed in 2014 and is operational in the current ATLAS data taking. The IBL detector is cooled with evaporative CO2 and is the first of its kind in ATLAS. The ATLAS IBL CO2 cooling system is designed for lower temperature operation (<-35⁰C) than the previous developed CO2 cooling systems in High Energy Physics experiments. The cold temperatures are required to protect the pixel sensors for the high expected radiation dose up to 550 fb^-1 integrated luminosity.

Radiation Protection Practices during the Helium Circulator Maintenance of the 10 MW High Temperature Gas-Cooled Reactor-Test Module (HTR-10

Directory of Open Access Journals (Sweden)

Chengxiang Guo

2016-01-01

Full Text Available Current radiation protection methodology offers abundant experiences on light-water reactors, but very few studies on high temperature gas-cooled reactor (HTR. To fill this gap, a comprehensive investigation was performed to the radiation protection practices in the helium circulator maintenance of the Chinese 10 MW HTR test module (HTR-10 in this paper. The investigation reveals the unique behaviour of HTR-10’s radiation sources in the maintenance as well as its radionuclide species and presents the radiation protection methods that were tailored to these features. Owing to these practices, the radioactivity level was kept low throughout the maintenance and only low-level radioactive waste was generated. The quantitative analysis further demonstrates that the decontamination efficiency was over 89% for surface contamination and over 34% for γ dose rate and the occupational exposure was much lower than both the limits of regulatory and the exposure levels in comparable literature. These results demonstrate the effectiveness of the reported radiation protection practices, which directly provides hands-on experience for the future HTR-PM reactor and adds to the completeness of the radiation protection methodology.

Importance of thermal radiation from heat sink in cooling of three phase PWM inverter kept inside an evacuated chamber

Directory of Open Access Journals (Sweden)

Anjan Sarkar

2017-04-01

Full Text Available The paper describes a thermal analysis of a three-phase inverter operated under a Sinusoidal Pulse Width Modulation (SPWM technique which used three sine waves displaced in 120° phase difference as reference signals. The IGBT unit is assumed to be placed with a heat sink inside an evacuated chamber and the entire heat has to be transferred by conduction and radiation. The main heat sources present here are the set of IGBTs and diodes which generates heat on a pulse basing on their switching frequencies. Melcosim (a well-known tool developed by Mitsubishi Electric Corporation has been used to generate the power pulse from one set of IGBT and diode connected to a phase. A Scilab code is written to study the conduction and thermal radiation of heat sink and their combined effect on transient growth of the junction temperature of IGBT unit against complex switching pulses. The results mainly show that how thermal radiation from heat sink plays a crucial role in maintaining the junction temperature of IGBT within a threshold limit by adjusting various heat sink parameters. As the IGBT heat generation rate becomes higher, radiative heat transfer of the heat sink increases sharply which enhances overall cooling performance of the system.

Use of fluorocarbons in the cooling of LHC experiments

CERN Document Server

Pimenta dos Santos, M

2003-01-01

Perfluorochemicals sold by 3M under the trade name 3M Fluorinert Electronic Liquids have been used for many years as heat transfer media in a variety of industries. The suitability of these liquids for the cooling of LHC experiment originates from their high dielectric strength as well as from their chemical stability under ionizing radiation. The Fluorinerts are clear, colorless, non-flammable with low toxicity and low corrosiveness. Additionally, they offer low global waming potential – GWP – and zero ozone-depletion potential – ODP. Some examples of fluorinert application in the cooling of LHC experiments will be presented : (a) the ATLAS Inner detector C3F8 evaporative cooling system (b) the ATLAS TRF C6F14 monophase cooling system and (c) the ALICE SPD “active heat pipe” C4F10 evaporative cooling system. A brief comparison of evaporative and monophase cooling systems will be outlined.

Generating a heated fluid using an electromagnetic radiation-absorbing complex

Science.gov (United States)

Halas, Nancy J.; Nordlander, Peter; Neumann, Oara

2018-01-09

A vessel including a concentrator configured to concentrate electromagnetic (EM) radiation received from an EM radiation source and a complex configured to absorb EM radiation to generate heat. The vessel is configured to receive a cool fluid from the cool fluid source, concentrate the EM radiation using the concentrator, apply the EM radiation to the complex, and transform, using the heat generated by the complex, the cool fluid to the heated fluid. The complex is at least one of consisting of copper nanoparticles, copper oxide nanoparticles, nanoshells, nanorods, carbon moieties, encapsulated nanoshells, encapsulated nanoparticles, and branched nanostructures. Further, the EM radiation is at least one of EM radiation in an ultraviolet region of an electromagnetic spectrum, in a visible region of the electromagnetic spectrum, and in an infrared region of the electromagnetic spectrum.

An enriched finite element model with q-refinement for radiative boundary layers in glass cooling

Energy Technology Data Exchange (ETDEWEB)

Mohamed, M. Shadi [Institute for Infrastructure and Environment, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Seaid, Mohammed; Trevelyan, Jon [School of Engineering and Computing Sciences, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Laghrouche, Omar [Institute for Infrastructure and Environment, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

2014-02-01

Radiative cooling in glass manufacturing is simulated using the partition of unity finite element method. The governing equations consist of a semi-linear transient heat equation for the temperature field and a stationary simplified P{sub 1} approximation for the radiation in non-grey semitransparent media. To integrate the coupled equations in time we consider a linearly implicit scheme in the finite element framework. A class of hyperbolic enrichment functions is proposed to resolve boundary layers near the enclosure walls. Using an industrial electromagnetic spectrum, the proposed method shows an immense reduction in the number of degrees of freedom required to achieve a certain accuracy compared to the conventional h-version finite element method. Furthermore the method shows a stable behaviour in treating the boundary layers which is shown by studying the solution close to the domain boundaries. The time integration choice is essential to implement a q-refinement procedure introduced in the current study. The enrichment is refined with respect to the steepness of the solution gradient near the domain boundary in the first few time steps and is shown to lead to a further significant reduction on top of what is already achieved with the enrichment. The performance of the proposed method is analysed for glass annealing in two enclosures where the simplified P{sub 1} approximation solution with the partition of unity method, the conventional finite element method and the finite difference method are compared to each other and to the full radiative heat transfer as well as the canonical Rosseland model.

Global albedo change and radiative cooling from anthropogenic land cover change, 1700 to 2005 based on MODIS, land use harmonization, radiative kernels, and reanalysis

Science.gov (United States)

Ghimire, Bardan; Williams, Christopher A.; Masek, Jeffrey; Gao, Feng; Wang, Zhuosen; Schaaf, Crystal; He, Tao

2014-12-01

Widespread anthropogenic land cover change over the last five centuries has influenced the global climate system through both biogeochemical and biophysical processes. Models indicate that warming from carbon emissions associated with land cover conversion has been partially offset by cooling from elevated albedo, but considerable uncertainty remains partly because of uncertainty in model treatments of albedo. This study incorporates a new spatially and temporally explicit, land cover specific albedo product derived from Moderate Resolution Imaging Spectroradiometer with a historical land use data set (Land Use Harmonization product) to provide more precise, observationally derived estimates of albedo impacts from anthropogenic land cover change with a complete range of data set specific uncertainty. The mean annual global albedo increase due to land cover change during 1700-2005 was estimated as 0.00106 ± 0.00008 (mean ± standard deviation), mainly driven by snow exposure due to land cover transitions from natural vegetation to agriculture. This translates to a top-of-atmosphere radiative cooling of -0.15 ± 0.1 W m-2 (mean ± standard deviation). Our estimate was in the middle of the Intergovernmental Panel on Climate Change Fifth Assessment Report range of -0.05 to -0.25 W m-2 and incorporates variability in albedo within land cover classes.

Solar thermoelectric cooling using closed loop heat exchangers with macro channels

Science.gov (United States)

Atta, Raghied M.

2017-07-01

In this paper we describe the design, analysis and experimental study of an advanced coolant air conditioning system which cools or warms airflow using thermoelectric (TE) devices powered by solar cells. Both faces of the TE devices are directly connected to closed-loop highly efficient channels plates with macro scale channels and liquid-to-air heat exchangers. The hot side of the system consists of a pump that moves a coolant through the hot face of the TE modules, a radiator that drives heat away into the air, and a fan that transfer the heat over the radiator by forced convection. The cold side of the system consists also of a pump that moves coolant through the cold face of the TE modules, a radiator that drives cold away into the air, and a fan that blows cold air off the radiator. The system was integrated with solar panels, tested and its thermal performance was assessed. The experimental results verify the possibility of heating or cooling air using TE modules with a relatively high coefficient of performance (COP). The system was able to cool a closed space of 30 m3 by 14 °C below ambient within 90 min. The maximum COP of the whole system was 0.72 when the TE modules were running at 11.2 Å and 12 V. This improvement in the system COP over the air cooled heat sink is due to the improvement of the system heat exchange by means of channels plates.

Supernova cooling in a dark matter smog

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yue, E-mail: yuezhang@theory.caltech.edu [Walter Burke Institute for Theoretical Physics, California Institute of Technology, Pasadena, CA 91125 (United States)

2014-11-01

A light hidden gauge boson with kinetic mixing with the usual photon is a popular setup in theories of dark matter. The supernova cooling via radiating the hidden boson is known to put an important constraint on the mixing. I consider the possible role dark matter, which under reasonable assumptions naturally exists inside supernova, can play in the cooling picture. Because the interaction between the hidden gauge boson and DM is likely unsuppressed, even a small number of dark matter compared to protons inside the supernova could dramatically shorten the free streaming length of the hidden boson. A picture of a dark matter ''smog'' inside the supernova, which substantially relaxes the cooling constraint, is discussed in detail.

Cooling analysis of a light emitting diode automotive fog lamp

Directory of Open Access Journals (Sweden)

Zadravec Matej

2017-01-01

Full Text Available Efficiency of cooling fins inside of a light emitting diode fog lamp is studied using computational fluid dynamics. Diffusion in heat sink, natural convection and radiation are the main principles of the simulated heat transfer. The Navier-Stokes equations were solved by the computational fluid dynamics code, including Monte Carlo radiation model and no additional turbulence model was needed. The numerical simulation is tested using the existing lamp geometry and temperature measurements. The agreement is excellent inside of few degrees at all measured points. The main objective of the article is to determine the cooling effect of various heat sink parts. Based on performed simulations, some heat sink parts are found to be very ineffective. The geometry and heat sink modifications are proposed. While radiation influence is significant, compressible effects are found to be minor.

Cooling system upgrading from 250 kW to 1 MW

International Nuclear Information System (INIS)

Anderson, T.V.; Johnson, A.G.; Ringle, J.C.

1972-01-01

The Oregon State TRIGA reactor (OSTR) power capability was upgraded from 250 KW to 1 MW in 1969; however, funds were not available for simultaneous upgrading of the cooling system. Since then, the OSTR has been selectively operating at full power with the original 250 KW cooling system. After funds were made available in 1971 the construction on the new heat exchanger building began. The new cooling system was installed, equipment was checked out, corrections were made, and acceptance tests were run. In addition, several days were required to clean up the primary system water, since increased water flow (350 gpm) swirled 4 year's collection of sediment off the reactor tank bottom and into the primary system. Three interesting items have been noticed, which are apparently a result of the cooling system upgrading: (1) the radiation levels above the reactor tank have been reduced by a factor of 2 to 3, (2) a low resonance vibration in the reactor core occurs at 1 MW. The vibration is attributed to a combination of increased water turbulence and subcooled (surface) nucleate boiling, and (3) direct radiation levels from the demineralizer tank have increased approximately 8-fold. This resulted in a relocation of the tank and the use of supplemental shielding. Increased operating time at higher average power levels, plus disturbance of; sediment on the bottom of the reactor tank are believed to be the main sources of the higher radiation levels

Artificial chameleon skin that controls spectral radiation: Development of Chameleon Cool Coating (C3).

Science.gov (United States)

Gonome, Hiroki; Nakamura, Masashi; Okajima, Junnosuke; Maruyama, Shigenao

2018-01-19

Chameleons have a diagnostic thermal protection that enables them to live under various conditions. Our developed special radiative control therefore is inspired by the chameleon thermal protection ability by imitating its two superposed layers as two pigment particles in one coating layer. One particle imitates a chameleon superficial surface for color control (visible light), and another particle imitates a deep surface to reflect solar irradiation, especially in the near-infrared region. Optical modeling allows us to optimally design the particle size and volume fraction. Experimental evaluation shows that the desired spectral reflectance, i.e., low in the VIS region and high in NIR region, can be achieved. Comparison between the measured and calculated reflectances shows that control of the particle size and dispersion/aggregation of particle cloud is important in improving the thermal-protection performance of the coating. Using our developed coating, the interior temperature decreases and the cooling load is reduced while keeping the dark tone of the object.

The ATLAS IBL CO2 Cooling System

CERN Document Server

Verlaat, Bartholomeus; The ATLAS collaboration

2016-01-01

The Atlas Pixel detector has been equipped with an extra B-layer in the space obtained by a reduced beam pipe. This new pixel detector called the ATLAS Insertable B-Layer (IBL) is installed in 2014 and is operational in the current ATLAS data taking. The IBL detector is cooled with evaporative CO2 and is the first of its kind in ATLAS. The ATLAS IBL CO2 cooling system is designed for lower temperature operation (<-35⁰C) than the previous developed CO2 cooling systems in High Energy Physics experiments. The cold temperatures are required to protect the pixel sensors for the high expected radiation dose up to 550 fb^-1 integrated luminosity. This paper describes the design, development, construction and commissioning of the IBL CO2 cooling system. It describes the challenges overcome and the important lessons learned for the development of future systems which are now under design for the Phase-II upgrade detectors.

An active cooling system for photovoltaic modules

International Nuclear Information System (INIS)

Teo, H.G.; Lee, P.S.; Hawlader, M.N.A.

2012-01-01

The electrical efficiency of photovoltaic (PV) cell is adversely affected by the significant increase of cell operating temperature during absorption of solar radiation. A hybrid photovoltaic/thermal (PV/T) solar system was designed, fabricated and experimentally investigated in this work. To actively cool the PV cells, a parallel array of ducts with inlet/outlet manifold designed for uniform airflow distribution was attached to the back of the PV panel. Experiments were performed with and without active cooling. A linear trend between the efficiency and temperature was found. Without active cooling, the temperature of the module was high and solar cells can only achieve an efficiency of 8–9%. However, when the module was operated under active cooling condition, the temperature dropped significantly leading to an increase in efficiency of solar cells to between 12% and 14%. A heat transfer simulation model was developed to compare to the actual temperature profile of PV module and good agreement between the simulation and experimental results is obtained.

Standing Slow MHD Waves in Radiatively Cooling Coronal Loops ...

Indian Academy of Sciences (India)

The standing slow magneto-acoustic oscillations in cooling coronal loops ... turbation and, eventually, reduces the MHD equations to a 1D system modelling ..... where the function Q is expanded in power series with respect to ǫ, i.e.,. Q = Q0 + ...

In-Service Inspection Approaches for Lead-Cooled Nuclear Reactors

Science.gov (United States)

2017-06-01

heavily regulated and mature. For example, the Illinois Emergency Management Agency (IEMA) conducted 805 soil samples testing for radionuclides around... radiation , and lead-cooled reactors are expected to have economic advantages compared to other nuclear coolant/moderator systems due to design...their six nuclear reactors in 22 2015 (IEMA, 2016, 3). In addition, they currently have 1649 environmental dosimeters testing for gamma radiation

ELECTRONIC CIRCUIT BOARDS NON-UNIFORM COOLING SYSTEM MODEL

Directory of Open Access Journals (Sweden)

D. V. Yevdulov

2016-01-01

Full Text Available Abstract. The paper considers a mathematical model of non-uniform cooling of electronic circuit boards. The block diagram of the system implementing this approach, the method of calculation of the electronic board temperature field, as well as the principle of its thermal performance optimizing are presented. In the considered scheme the main heat elimination from electronic board is produced by the radiator system, and additional cooling of the most temperature-sensitive components is produced by thermoelectric batteries. Are given the two-dimensional temperature fields of the electronic board during its uniform and non-uniform cooling, is carried out their comparison. As follows from the calculations results, when using a uniform overall cooling of electronic unit there is a waste of energy for the cooling 0f electronic board parts which temperature is within acceptable temperature range without the cooling system. This approach leads to the increase in the cooling capacity of used thermoelectric batteries in comparison with the desired values. This largely reduces the efficiency of heat elimination system. The use for electronic boards cooling of non-uniform local heat elimination removes this disadvantage. The obtained dependences show that in this case, the energy required to create a given temperature is smaller than when using a common uniform cooling. In this approach the temperature field of the electronic board is more uniform and the cooling is more efficient. 

Constraints on the interaction between dark matter and Baryons from cooling flow clusters.

Science.gov (United States)

Qin, B; Wu, X P

2001-08-06

Other nongravitational heating processes are needed to resolve the disagreement between the absence of cool gas components in the centers of galaxy clusters revealed recently by Chandra and XMM observations and the expectations of conventional radiative cooling models. We propose that the interaction between dark matter and baryonic matter may act as an alternative for the reheating of intracluster medium (ICM) in the inner regions of clusters, in which kinetic energy of dark matter is transported to ICM to balance radiative cooling. Using the Chandra and XMM data, we set a useful constraint on the dark-matter-baryon cross section: sigma(xp)/m(x) approximately 1x10(-25) cm(2) GeV-1, where m(x) is the mass of dark matter particles.

Status of and prospects for gas-cooled reactors

International Nuclear Information System (INIS)

1984-01-01

The IAEA International Working Group on Gas-Cooled Reactors (IWGGCR) (see Annex I), which was established in 1978, recommended to the Agency that a report be prepared in order to provide an up-to-date summary of gas-cooled reactor technology. The present Technical Report is based mainly on submissions of Member Countries of the IWGGCR and consists of four main sections. Beside some general information about the gas-cooled reactor line, section 1 contains a description of the incentives for the development and deployment of gas-cooled reactors in various Agency Member States. These include both electricity generation and process steam and process heat production for various branches of industry. The historical development of gas-cooled reactors is reviewed in section 2. In this section information is provided on how, when and why gas-cooled reactors have been developed in various Agency Member States and, in addition, a detailed description of the different gas-cooled reactor lines is presented. Section 3 contains information about the technical status of gas-cooled reactors and their applications. Gas-cooled reactors that are under design or construction or in operation are listed and shortly described, together with an outlook for future reactor designs. In this section the various applications for gas-cooled reactors are described in detail. These include both electricity generation and process steam and process heat production. The last section (section 4) is entitled ''Special features of gas-cooled reactors'' and contains information about the technical performance, fuel utilization, safety characteristics and environmental impact, such as radiation exposure and heat rejection

Large wet-type cooling towers and their influence on the environment

International Nuclear Information System (INIS)

Schiffers, A.

1977-01-01

Large wet-type cooling towers with natural draft are said to be ecologically beneficial today, especially concerning the heat emission from power plants. A description is given of the influence of such cooling towers on the environment and the possible climatic influences are considered in detail. Recent investigations have shown that wet-type cooling towers represent no danger of any kind for fauna and flora as to the bacterial radiation. Physical studies have shown that neither the emitted water vapour nor the heat emitted into the atmosphere, can significantly change the macroclimate and microclimate. At present, wet-type cooling towers cannot be replaced by dry-type or so-called hybrid-type cooling towers, the technical development of which for large units being not yet guaranteed. (orig.) [de

Radiation observation at Dome Fuji Station, Antarctica

Directory of Open Access Journals (Sweden)

Naohiko Hirasawa

2008-06-01

Full Text Available This paper reports radiation observations at Dome Fuji Station from February 1, 2003 to January 20, 2004, carried out by the 44th Japanese Antarctic Research Expedition team. The radiometers which measured the upward longwave radiation (LWu, the downward longwave (LWd and the downward shortwave (SWd were equipped with fans to avoid frosting on the surface of the radiometer dome by air circulation. The upward shortwave radiation (SWu measured by a radiometer without fan needs correction, which we leave as a problem for the future. In addition, as for LWd and LWu in the polar night, a typical radiational cooling case and a suppressed radiational cooling one are shown.

A study of a wind catcher assisted adsorption cooling channel for natural cooling of a 2-storey building

International Nuclear Information System (INIS)

Haghighi, A.P.; Pakdel, S.H.; Jafari, A.

2016-01-01

This study proposes a new system composing of a wind catcher and a solar driven two-bed silica gel–water adsorption chiller in order to provide natural cooling of a two-story building. The wind catcher provides the required ventilation, and the air flowing though the wind catcher is cooled by the cooling plates fed by the adsorption chiller. The performance of the system is studied theoretically under different ambient conditions such as wind velocity, solar radiation, air temperature and relative humidity. In addition, the influence of geometric parameters such as size of the apertures, wind catcher's height and dimensions of the cooling plates and the number of them are studied. Furthermore, the system's capability to provide thermal comfort in the living space is investigated. It is found that at lower ACH (air change per hour) values, inlet air's temperature and absolute humidity reduce more. In addition, with the rise of the cooling plates' length, the cooling effect increases. The results indicated that with the increase of ACH values, thermal comfort condition is achieved for larger cooling demands. Furthermore, the system was found to be able to cool the air between 10 and 20 °C under different ambient conditions. - Highlights: • A new system consisting of a wind catcher and a solar adsorption chiller is proposed. • The values of ACH were compared under different geometrical parameters. • With the increase of ACH, thermal comfort can be achieved for larger cooling demands. • Thermal comfort is achieved for a maximum of 2200 W cooling demand in a 50 m 3 room. • Application of the system is found to be beneficial in hot and humid climates.

Wind-break walls with optimized setting angles for natural draft dry cooling tower with vertical radiators

International Nuclear Information System (INIS)

Ma, Huan; Si, Fengqi; Kong, Yu; Zhu, Kangping; Yan, Wensheng

2017-01-01

Highlights: • Aerodynamic field around dry cooling tower is presented with numerical model. • Performances of cooling deltas are figured out by air inflow velocity analysis. • Setting angles of wind-break walls are optimized to improve cooling performance. • Optimized walls can reduce the interference on air inflow at low wind speeds. • Optimized walls create stronger outside secondary flow at high wind speeds. - Abstract: To get larger cooling performance enhancement for natural draft dry cooling tower with vertical cooling deltas under crosswind, setting angles of wind-break walls were optimized. Considering specific structure of each cooling delta, an efficient numerical model was established and validated by some published results. Aerodynamic fields around cooling deltas under various crosswind speeds were presented, and outlet water temperatures of the two columns of cooling delta were exported as well. It was found that for each cooling delta, there was a difference in cooling performance between the two columns, which is closely related to the characteristic of main airflow outside the tower. Using the present model, air inflow deviation angles at cooling deltas’ inlet were calculated, and the effects of air inflow deviation on outlet water temperatures of the two columns for corresponding cooling delta were explained in detail. Subsequently, at cooling deltas’ inlet along radial direction of the tower, setting angles of wind-break walls were optimized equal to air inflow deviation angles when no airflow separation appeared outside the tower, while equal to zero when outside airflow separation occurred. In addition, wind-break walls with optimized setting angles were verified to be extremely effective, compared to the previous radial walls.

Split radiator design for heat rejection optimization for a waste heat recovery system

Science.gov (United States)

Ernst, Timothy C.; Nelson, Christopher R.

2016-10-18

A cooling system provides improved heat recovery by providing a split core radiator for both engine cooling and condenser cooling for a Rankine cycle (RC). The cooling system includes a radiator having a first cooling core portion and a second cooling core portion. An engine cooling loop is fluidly connected the second cooling core portion. A condenser of an RC has a cooling loop fluidly connected to the first cooling core portion. A valve is provided between the engine cooling loop and the condenser cooling loop adjustably control the flow of coolant in the condenser cooling loop into the engine cooling loop. The cooling system includes a controller communicatively coupled to the valve and adapted to determine a load requirement for the internal combustion engine and adjust the valve in accordance with the engine load requirement.

Effects of different cooling principles on thermal sensation and physiological responses

DEFF Research Database (Denmark)

Schellen, Lisje; Loomans, Marcel G.L.C.; De Wit, Martin H.

2013-01-01

Applying low exergy cooling concepts in the built environment allows reduction of use of high quality energy sources. Non-uniform thermal conditions, which may occur due to application of lowex systems, can result in discomfort. Two different cooling principles were studied: passive (through...... by the floor and mixing ventilation, and (6) AC-R-D-F; active cooling through radiation by the floor and displacement ventilation. Though all cases were designed at PMV ≈ 0, subjective data indicate significant differences between the cases. For the prediction of thermal sensation and thermal comfort under non...

Fossil fuel and biomass burning effect on climate - heating or cooling

Energy Technology Data Exchange (ETDEWEB)

Kaufman, Y.J.; Fraser, R.S.; Mahoney, R.L. (NASA/Goddard Space Flight Center, Greenbelt, MD (USA))

1991-06-01

Emission from burning of fossil fuels and biomass (associated with deforestation) generates a radiative forcing on the atmosphere and a possible climate change. Emitted trace gases heat the atmosphere through their greenhouse effect, while particulates formed from emitted SO{sub 2} cause cooling by increasing cloud albedos through alteration of droplet size distributions. This paper reviews the characteristics of the cooling effect and applies Twomey's theory to check whether the radiative balance favours heating or cooling for the cases of fossil fuel and biomass burning. It is also shown that although coal and oil emit 120 times as many CO{sub 2} molecules as SO{sub 2} molecules, each SO{sub 2} molecule is 50-1100 times more effective in cooling the atmosphere (through the effect of aerosol particles on cloud albedo) than a CO{sub 2} molecule is in heating it. Note that this ratio accounts for the large difference in the aerosol (3-10 days) and CO{sub 2} (7-100 years) lifetimes. It is concluded, that the cooling effect from coal and oil burning may presently range from 0.4 to 8 times the heating effect. Within this large uncertainty, it is presently more likely that fossil fuel burning causes cooling of the atmosphere rather than heating. Biomass burning associated with deforestation, on the other hand, is more likely to cause heating of the atmosphere than cooling since its aerosol cooling effect is only half that from fossil fuel burning and its heating effect is twice as large. Future increases in coal and oil burning, and the resultant increase in concentration of cloud condensation nuclei, may saturate the cooling effect, allowing the heating effect to dominate. For a doubling in the CO{sub 2} concentration due to fossil fuel burning, the cooling effect is expected to be 0.1 to 0.3 of the heating effect. 75 refs., 8 tabs.

Storage chamber for container of radiation-contaminated material

International Nuclear Information System (INIS)

Takakura, Masahide.

1996-01-01

The present invention concerns a storage chamber for containing radiation-contaminated materials in containing tubes and having cooling fluids circulated at the outer side of the containing tubes. The storage chamber comprises a gas supply means connected to the inside of the container tube for supplying a highly heat-conductive gas and a gas exhaustion means for discharging the gas present in the container tube. When containing vessels for radiation-contaminated materials are contained in the container tube, the gases present inside of the container tube is exhausted by means of the gas exhaustion means, and highly heat conductive gases are filled from the gas supply means to the space between the container tube and the containing vessels for the radiation-contaminated materials. When the temperature of the highly heat conductive gas is elevated due to the heat generation of the radiation-contaminated materials, the container tube is heated, and then cooled by the cooling fluid at the outer side of the container tube. In this case, the heat of the radiation-contaminated material-containing vessels is removed by the heat conduction by the highly heat conductive gas to reduce temperature gradient between the containing vessels and the containing tube. This can enhance the cooling effect. (T.M.)

Turbine airfoil cooling system with cooling systems using high and low pressure cooling fluids

Science.gov (United States)

Marsh, Jan H.; Messmann, Stephen John; Scribner, Carmen Andrew

2017-10-25

A turbine airfoil cooling system including a low pressure cooling system and a high pressure cooling system for a turbine airfoil of a gas turbine engine is disclosed. In at least one embodiment, the low pressure cooling system may be an ambient air cooling system, and the high pressure cooling system may be a compressor bleed air cooling system. In at least one embodiment, the compressor bleed air cooling system in communication with a high pressure subsystem that may be a snubber cooling system positioned within a snubber. A delivery system including a movable air supply tube may be used to separate the low and high pressure cooling subsystems. The delivery system may enable high pressure cooling air to be passed to the snubber cooling system separate from low pressure cooling fluid supplied by the low pressure cooling system to other portions of the turbine airfoil cooling system.

A passive cooling system proposal for multifunction and high-power displays

Science.gov (United States)

Tari, Ilker

2013-03-01

Flat panel displays are conventionally cooled by internal natural convection, which constrains the possible rate of heat transfer from the panel. On one hand, during the last few years, the power consumption and the related cooling requirement for 1080p displays have decreased mostly due to energy savings by the switch to LED backlighting and more efficient electronics. However, on the other hand, the required cooling rate recently started to increase with new directions in the industry such as 3D displays, and ultra-high-resolution displays (recent 4K announcements and planned introduction of 8K). In addition to these trends in display technology itself, there is also a trend to integrate consumer entertainment products into displays with the ultimate goal of designing a multifunction device replacing the TV, the media player, the PC, the game console and the sound system. Considering the increasing power requirement for higher fidelity in video processing, these multifunction devices tend to generate very high heat fluxes, which are impossible to dissipate with internal natural convection. In order to overcome this obstacle, instead of active cooling with forced convection that comes with drawbacks of noise, additional power consumption, and reduced reliability, a passive cooling system relying on external natural convection and radiation is proposed here. The proposed cooling system consists of a heat spreader flat heat pipe and aluminum plate-finned heat sink with anodized surfaces. For this system, the possible maximum heat dissipation rates from the standard size panels (in 26-70 inch range) are estimated by using our recently obtained heat transfer correlations for the natural convection from aluminum plate-finned heat sinks together with the surface-to-surface radiation. With the use of the proposed passive cooling system, the possibility of dissipating very high heat rates is demonstrated, hinting a promising green alternative to active cooling.

Research for Actively Reducing Infrared Radiation by Thermoelectric Refrigerator

Energy Technology Data Exchange (ETDEWEB)

Kim, Hoon; Kim, Kyomin; Kim, Woochul [Yonsei Univ., Seoul (Korea, Republic of)

2017-03-15

We introduced a technology for reducing infrared radiation through the active cooling of hot surfaces by using a thermoelectric refrigerator. Certain surfaces were heated by aerodynamic heating, and the heat generation processes are proposed here. We calculated the temperatures and radiations from surfaces, while using thermoelectric refrigerators to cool the surfaces. The results showed that the contrast between the radiations of certain surfaces and the ambient environments can be removed using thermoelectric refrigerators.

CFD Analyses on LHe Cooling for SCQ Magnets in BEPCII Upgrade

International Nuclear Information System (INIS)

He, Z.H.; Wang, L.; Tang, H.M.; Zhang, X.B.; Jia, L.X.

2004-01-01

A pair of superconducting interaction region quadrupole magnets in Beijing Electron-Positron Collider Upgrade (BEPCII) are to be cooled by supercritical helium in order to eliminate the flow instabilities in the constrained cooling channels. The fluid flow is simulated by the commercial computational dynamics fluid software. The heat loads to the superconducting quadrupole (SCQ) magnets from the radiation shields at 80 K and from the thermal conduction of mechanical supports are considered. The temperature distribution of the fluid in the liquid helium cooling channels, and the heat transfer in the SCQ magnet and by its supports are presented. The influence of mass flow rate on pressure drop in the cooling passage is analyzed

Energy and water management in evaporative cooling systems in Saudi Arabia

Energy Technology Data Exchange (ETDEWEB)

Kassem, Abdel-wahab S. (Agricultural and Veterinary Training and Research Station, King Faisal University, Al-Hassa (Saudi Arabia))

1994-11-01

A mathematical model was developed to estimate water evaporation rate, airflow rate and cooling effect in an evaporative cooling system for farm structures. The model was only applied to evaporative cooling systems for greenhouses. The effect of ambient air temperature, solar radiation and system efficiency on water evaporation rate, airflow rate and the resulting cooling effect were studied. Generally, water flow rate and air flow rate are adjusted based on daily maximum temperature. However, a substantial saving in energy and water consumption in the cooling system would be achieved by regulating water flow rate and air flow rate to follow the diurnal variation on temperature. Improving the cooling efficiency and covering the roof of the greenhouse with an external shading would save an appreciable amount of energy and water consumption. The model could also be applied to other farm structures such as animal shelters

Scale Modelling of Nocturnal Cooling in Urban Parks

Science.gov (United States)

Spronken-Smith, R. A.; Oke, T. R.

Scale modelling is used to determine the relative contribution of heat transfer processes to the nocturnal cooling of urban parks and the characteristic temporal and spatial variation of surface temperature. Validation is achieved using a hardware model-to-numerical model-to-field observation chain of comparisons. For the calm case, modelling shows that urban-park differences of sky view factor (s) and thermal admittance () are the relevant properties governing the park cool island (PCI) effect. Reduction in sky view factor by buildings and trees decreases the drain of longwave radiation from the surface to the sky. Thus park areas near the perimeter where there may be a line of buildings or trees, or even sites within a park containing tree clumps or individual trees, generally cool less than open areas. The edge effect applies within distances of about 2.2 to 3.5 times the height of the border obstruction, i.e., to have any part of the park cooling at the maximum rate a square park must be at least twice these dimensions in width. Although the central areas of parks larger than this will experience greater cooling they will accumulate a larger volume of cold air that may make it possible for them to initiate a thermal circulation and extend the influence of the park into the surrounding city. Given real world values of s and it seems likely that radiation and conduction play almost equal roles in nocturnal PCI development. Evaporation is not a significant cooling mechanism in the nocturnal calm case but by day it is probably critical in establishing a PCI by sunset. It is likely that conditions that favour PCI by day (tree shade, soil wetness) retard PCI growth at night. The present work, which only deals with PCI growth, cannot predict which type of park will be coolest at night. Complete specification of nocturnal PCI magnitude requires knowledge of the PCI at sunset, and this depends on daytime energetics.

A three-dimensional mathematical model to predict air-cooling flow and temperature distribution of wire loops in the Stelmor air-cooling system

International Nuclear Information System (INIS)

Hong, Lingxiang; Wang, Bo; Feng, Shuai; Yang, Zhiliang; Yu, Yaowei; Peng, Wangjun; Zhang, Jieyu

2017-01-01

Highlights: • A 3-dimentioanl mathematical models for complex wire loops was set up in Stelmor. • The air flow field in the cooling process was simulated. • The convective heat transfer coefficient was simulated coupled with air flow field. • The temperature distribution with distances was predicted. - Abstract: Controlling the forced air cooling conditions in the Stelmor conveyor line is important for improving the microstructure and mechanical properties of steel wire rods. A three-dimensional mathematical model incorporating the turbulent flow of the cooling air and heat transfer of the wire rods was developed to predict the cooling process in the Stelmor air-cooling line of wire rolling mills. The distribution of cooling air from the plenum chamber and the forced convective heat transfer coefficient for the wire loops were simulated at the different locations over the conveyor. The temperature profiles and cooling curves of the wire loops in Stelmor conveyor lines were also calculated by considering the convective heat transfer, radiative heat transfer as well as the latent heat during transformation. The calculated temperature results using this model agreed well with the available measured results in the industrial tests. Thus, it was demonstrated that this model can be useful for studying the air-cooling process and predicting the temperature profile and microstructure evolution of the wire rods.

Daytime space cooling with phase change material ceiling panels discharged using rooftop photovoltaic/thermal panels and night-time ventilation

DEFF Research Database (Denmark)

Bourdakis, Eleftherios; Pean, Thibault Quentin; Gennari, Luca

2016-01-01

The possibility of using photovoltaic/thermal panels for producing cold water through the process of night-time radiative cooling was experimentally examined. The cold water was used to discharge phase change material in ceiling panels in a climatic chamber. Both night-time radiative cooling...... the photovoltaic/thermal varied from 56% to 122%. The phase change material ceiling panels were thus, capable of providing an acceptable thermal environment and the photovoltaic/thermal panels were able to provide most of the required electricity and cold water needed for cooling....

EXPERIMENTAL VERIFICATION OF COMPUTER MODEL OF COOLING SYSTEM FOR POWERFUL SEMI- CONDUCTOR DEVICE

Directory of Open Access Journals (Sweden)

I. A. Khorunzhii

2007-01-01

Full Text Available A cooling system for powerful semi-conductor device (power -1 kW consisting of a pin-type radiator and a body is considered in the paper. Cooling is carried out by forced convection of a coolant. Calculated values of temperatures on the radiator surface and experimentally measured values of temperatures in the same surface points have been compared in the paper. It has been shown that the difference between calculated and experimentally measured temperatures does not exceed 0,1-0,2 °C and it is comparable with experimental error value. The given results confirm correctness of a computer model.

Influence of materials choice on occupational radiation exposure in ITER

International Nuclear Information System (INIS)

Forty, C.B.A.; Firth, J.D.; Butterworth, G.J.

1998-01-01

In fission reactor plant, the radiation doses associated with inspection and maintenance of the primary cooling circuit account for a substantial fraction of the collective occupational radiation exposure (ORE). Similarly, it is anticipated that much of the ORE occurring during normal operation of ITER will arise from active deposits in the cooling loop. Using a number of calculation steps ranging from neutron activation analysis, mobilisation and transport modelling and Monte Carlo simulation, estimates for the gamma photon flux and radiation dose fields around a typical 'hot-leg' cooling pipe have been made taking SS316, OPTSTAB, MANET-II and F-82H steels as alternative candidate loop materials. (orig.)

Experimental study of discharging PCM ceiling panels through nocturnal radiative cooling

DEFF Research Database (Denmark)

Bourdakis, Eleftherios; Péan, Thibault Q.; Gennari, Luca

2016-01-01

rate (96 l/h) in the solar loop provided the highest average cooling power, due to the significant variations in the weather conditions during the three experimental cases, made it impossible to determine to which extent the difference in the cooling power is due to the different water flow rate....... The percentage of electrical energy use that could be covered from the PV/Ts on site was 71.5% for Case 1, 68.3% for Case 2 and 86.8% for Case 3. In any case, the PV/T panels proved to be an efficient solution for the production of electrical energy, heated and chilled water....

Sympathetic cooling and crystallization of ions in a linear Paul trap

International Nuclear Information System (INIS)

Drewsen, M.; Bowe, P.; Hornekaer, L.; Brodersen, C.; Schiffer, J.P.; Hangst, J.S.; Schiffer, J.P.

1999-01-01

Coulomb crystals, containing up to a few hundred ions of which more than 50% were cooled sympathetically by the Coulomb interaction with laser cooled Mg + ions, have been produced in a linear Paul trap. By controlling the balance of the radiation pressure from the two cooling lasers, the Coulomb crystals could be segregated according to ion species. Previous studies of ion crystals and molecular dynamics simulations suggest that the temperature may be around 10 mK or lower. The obtained results indicate that a wide range of atomic and molecular ions, which due to their internal structures are not amenable to direct laser cooling, can be effectively cooled and localized (crystallized) in linear Paul traps. For high resolution spectroscopy of such ions this may turn out to be very useful. copyright 1999 American Institute of Physics

Study of natural energy system and downward atmospheric radiation. Part 2. Study of downward atmospheric radiation simple estimated formula and elective longwave radiation; Shizen energy system to tenku hosharyo no kansoku kenkyu. 2. Tenku hosharyo kan`i suiteishiki to jikko hosharyo no kento

Energy Technology Data Exchange (ETDEWEB)

Ohashi, K; Yano, S [Kogakuin University, Tokyo (Japan); Masuoka, Y

1997-11-25

With an objective to design and control a natural energy utilization system, this paper describes discussions on a simple estimation formula for downward atmospheric radiation. The simple estimation formula for downward atmospheric radiation using a square root of steam partial pressure, {sigma}T{sup 4} ({sigma} is the Stefan Boltzmann constant, and T is the absolute outside air temperature), and SAT (observation value for corresponding outside air temperature) as explanatory variables was added with data made available further to improve its accuracy. A calculated value, whose formula had observation values at each location substituted, had coefficient of correlation with the observation values of 0.9. This formula was found applicable to each location. The effective radiation amount is the difference between the downward atmospheric radiation and the long wavelength radiation from the ground surface, from which a formula to simply estimate the effective radiation was proposed. Although there is a slight difference, the calculated values derived by using this formula agreed nearly well with the observation values of the effective radiation. A standard SAT meter was used to discuss cooling effect of atmospheric radiation cooling on the ground surface, whereas the cooling effect was verified to appear markedly under windless condition at night. It was found that the cooling effect is more remarkable in winter than in summer. 14 refs., 8 figs., 1 tab.

NPR and ANSI Containment Study Using Passive Cooling Techniques

International Nuclear Information System (INIS)

Shin, J. J.; Iotti, R. C.; Wright, R. F.

1993-01-01

Passive containment cooling study of NPR (New Production Reactor) and ANSI (Advanced Neutron Source) following postulated loss of coolant accident with a coincident station blackout due to total loss of all alternating current power are studied analytically and experimentally. All the reactor and containment cooling under this condition would rely on the passive cooling system which removes reactor decay heat and provides emergency core and containment cooling. Containment passive emergency core and containment cooling. Containment passive cooling for this study takes place in the annulus between containment steel shell and concrete shield building by natural convection air flow and concrete shield building by natural convection air flow and thermal radiation. Various heat transfer coefficients inside annular air space were investigated by running the modified Contempt code Contempt-Npr. In order to verify proper heat transfer coefficient, temperature, heat flux and velocity profiles were measured inside annular air space of the test facility which is a 24 foot (7.3m) high, steam heated inner cylinder of three foot (.91m) diameter and five and halt foot (1.7m) diameter outer cylinder. Comparison of Contempt-Npr and WGOTHIC was done for reduced scale Npr. It is concluded that Npr and ANSI containments can be passively cooled with air alone without extended cooling surfaces or passive water spray

Simplified Building Thermal Model Used for Optimal Control of Radiant Cooling System

Directory of Open Access Journals (Sweden)

Lei He

2016-01-01

Full Text Available MPC has the ability to optimize the system operation parameters for energy conservation. Recently, it has been used in HVAC systems for saving energy, but there are very few applications in radiant cooling systems. To implement MPC in buildings with radiant terminals, the predictions of cooling load and thermal environment are indispensable. In this paper, a simplified thermal model is proposed for predicting cooling load and thermal environment in buildings with radiant floor. In this thermal model, the black-box model is introduced to derive the incident solar radiation, while the genetic algorithm is utilized to identify the parameters of the thermal model. In order to further validate this simplified thermal model, simulated results from TRNSYS are compared with those from this model and the deviation is evaluated based on coefficient of variation of root mean square (CV. The results show that the simplified model can predict the operative temperature with a CV lower than 1% and predict cooling loads with a CV lower than 10%. For the purpose of supervisory control in HVAC systems, this simplified RC thermal model has an acceptable accuracy and can be used for further MPC in buildings with radiation terminals.

Structure and thermal analysis of the water cooling mask at NSRL front end

International Nuclear Information System (INIS)

Zhao Feiyun; Xu Chaoyin; Wang Qiuping; Wang Naxiu

2003-01-01

A water cooling mask is an important part of the front end, usually used for absorbing high power density synchrotron radiation to protect the apparatus from being destroyed by heat load. This paper presents the structure of the water cooling mask and the thermal analysis results of the mask block at NSRL using Program ANSYS5.5

Experimental investigations on the cooling of a motorcycle helmet with phase change material (PCM

Directory of Open Access Journals (Sweden)

Fok S.C.

2011-01-01

Full Text Available The thermal comfort of motorcycle helmet during hot weather is important as it can affect the physiological and psychological condition of the rider. This paper examines the use of phase change material (PCM to cool a motorcycle helmet and presents the experimental investigations on the influences of the simulated solar radiation, wind speed, and heat generation rate on the cooling system. The result shows that the PCM-cooled helmet is able to prolong the thermal comfort period compared to a normal helmet. The findings also indicate that the heat generation from the head is the predominant factor that will affect the PCM melting time. Simulated solar radiation and ram-air due to vehicle motion under adiabatic condition can have very little influences on the PCM melting time. The results suggested that the helmet usage time would be influenced by the amount of heat generated from the head. Some major design considerations based on these findings have been included. Although this investigation focuses on the cooling of a motorcyclist helmet, the findings would also be useful for the development of PCM-cooling systems in other applications.

Sensitivity of energy and exergy performances of heating and cooling systems to auxiliary components

DEFF Research Database (Denmark)

Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

2017-01-01

. Different forms of energy (electricity and heat) are used in heating and cooling systems, and therefore, a holistic approach to system design and analysis is needed. In particular, distribution systems use electricity as a direct input to pumps and fans, and to other components. Therefore, exergy concept......Heating and cooling systems in buildings consist of three main subsystems: heating/cooling plant, distribution system, and indoor terminal unit. The choice of indoor terminal unit determines the characteristics of the distribution system and the heating and cooling plants that can be used...... should be used in design and analysis of the whole heating and cooling systems, in addition to the energy analysis. In this study, water-based (floor heating and cooling, and radiator heating) and air-based (air heating and cooling) heating and cooling systems were compared in terms of their energy use...

Cool-flame Extinction During N-Alkane Droplet Combustion in Microgravity

Science.gov (United States)

Nayagam, Vedha; Dietrich, Daniel L.; Hicks, Michael C.; Williams, Forman A.

2014-01-01

Recent droplet combustion experiments onboard the International Space Station (ISS) have revealed that large n-alkane droplets can continue to burn quasi-steadily following radiative extinction in a low-temperature regime, characterized by negative-temperaturecoefficient (NTC) chemistry. In this study we report experimental observations of n-heptane, n-octane, and n-decane droplets of varying initial sizes burning in oxygen/nitrogen/carbon dioxide and oxygen/helium/nitrogen environments at 1.0, 0.7, and 0.5 atmospheric pressures. The oxygen concentration in these tests varied in the range of 14% to 25% by volume. Large n-alkane droplets exhibited quasi-steady low-temperature burning and extinction following radiative extinction of the visible flame while smaller droplets burned to completion or disruptively extinguished. A vapor-cloud formed in most cases slightly prior to or following the "cool flame" extinction. Results for droplet burning rates in both the hot-flame and cool-flame regimes as well as droplet extinction diameters at the end of each stage are presented. Time histories of radiant emission from the droplet captured using broadband radiometers are also presented. Remarkably the "cool flame" extinction diameters for all the three n-alkanes follow a trend reminiscent of the ignition delay times observed in previous studies. The similarities and differences among the n-alkanes during "cool flame" combustion are discussed using simplified theoretical models of the phenomenon

The impact of microwave stray radiation to in-vessel diagnostic components

Energy Technology Data Exchange (ETDEWEB)

Hirsch, M.; Laqua, H. P.; Hathiramani, D.; Baldzuhn, J.; Biedermann, C.; Cardella, A.; Erckmann, V.; König, R.; Köppen, M.; Zhang, D. [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, EURATOM Association, D-17489 Greifswald (Germany); Oosterbeek, J.; Brand, H. von der; Parquay, S. [Technische Universiteit Eindhoven, department Technische Natuurkunde, working group for Plasma Physics and Radiation Technology, Den Doelch 2, 5612 AZ Eindhoven (Netherlands); Jimenez, R. [Centro de Investigationes Energeticas, Medioambientales y Technológicas, Association EURATOM/CIEMAT, Avenida Complutense 22, Madrid 28040 (Spain); Collaboration: W7-X Teasm

2014-08-21

Microwave stray radiation resulting from unabsorbed multiple reflected ECRH / ECCD beams may cause severe heating of microwave absorbing in-vessel components such as gaskets, bellows, windows, ceramics and cable insulations. In view of long-pulse operation of WENDELSTEIN-7X the MIcrowave STray RAdiation Launch facility, MISTRAL, allows to test in-vessel components in the environment of isotropic 140 GHz microwave radiation at power load of up to 50 kW/m{sup 2} over 30 min. The results show that both, sufficient microwave shielding measures and cooling of all components are mandatory. If shielding/cooling measures of in-vessel diagnostic components are not efficient enough, the level of stray radiation may be (locally) reduced by dedicated absorbing ceramic coatings on cooled structures.

DEVELOPMENT OF SHORT UNDULATORS FOR ELECTRON-BEAM-RADIATION INTERACTION STUDIES

Energy Technology Data Exchange (ETDEWEB)

Piot, P. [NICADD, DeKalb; Andorf, M. B. [NICADD, DeKalb; Fagerberg, G. [Northern Illinois U.; Figora, M. [Northern Illinois U.; Sturtz, A. [Northern Illinois U.

2016-10-19

Interaction of an electron beam with external field or its own radiation has widespread applications ranging from coherent-radiation generation, phase space cooling or formation of temporally-structured beams. An efficient coupling mechanism between an electron beam and radiation field relies on the use of a magnetic undulator. In this contribution we detail our plans to build short (11-period) undulators with 7-cm period refurbishing parts of the aladdin U3 undulator [1]. Possible use of these undulators at available test facilities to support experiments relevant to cooling techniques and radiation sources are outlined.

CFD ANALYSES ON THE COOLING FOR SCQ MAGNETS IN BEPC II UPGRADE

International Nuclear Information System (INIS)

HE, Z.H.; WANG, L.; TANK, H.M.; ZHANG, X.B.; JIA, L.X.

2003-01-01

A pair of superconducting interaction region quadrupole magnets in Beijing Electron-Positron Collider Upgrade (BEPCII) are to be cooled by supercritical helium in order to eliminate the flow instabilities in the constrained cooling channels. The fluid flow is simulated by the commercial computational dynamics fluid software. The heat loads to the superconducting quadrupole (SCQ) magnets from the radiation shields at 80 K and from the thermal conduction of mechanical supports are considered. The temperature distribution of the fluid in the liquid helium cooling channels, and the heat transfer in the SCQ magnet and by its supports are presented. The influence of mass flow rate on pressure drop in the cooling passage is analyzed

Radiative effects of global MODIS cloud regimes

Science.gov (United States)

Oreopoulos, Lazaros; Cho, Nayeong; Lee, Dongmin; Kato, Seiji

2018-01-01

We update previously published MODIS global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 dataset. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux datasets. Our results clearly show the CRs are radiatively distinct in terms of shortwave, longwave and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance datasets suffering from imperfect spatiotemporal matching depend on CR, and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations. PMID:29619289

Radiative Effects of Global MODIS Cloud Regimes

Science.gov (United States)

Oraiopoulos, Lazaros; Cho, Nayeong; Lee, Dong Min; Kato, Seiji

2016-01-01

We update previously published MODIS global cloud regimes (CRs) using the latest MODIS cloud retrievals in the Collection 6 dataset. We implement a slightly different derivation method, investigate the composition of the regimes, and then proceed to examine several aspects of CR radiative appearance with the aid of various radiative flux datasets. Our results clearly show the CRs are radiatively distinct in terms of shortwave, longwave and their combined (total) cloud radiative effect. We show that we can clearly distinguish regimes based on whether they radiatively cool or warm the atmosphere, and thanks to radiative heating profiles to discern the vertical distribution of cooling and warming. Terra and Aqua comparisons provide information about the degree to which morning and afternoon occurrences of regimes affect the symmetry of CR radiative contribution. We examine how the radiative discrepancies among multiple irradiance datasets suffering from imperfect spatiotemporal matching depend on CR, and whether they are therefore related to the complexity of cloud structure, its interpretation by different observational systems, and its subsequent representation in radiative transfer calculations.

Suncatcher and cool pool. Project report

Energy Technology Data Exchange (ETDEWEB)

Hammond, J.

1981-03-01

The Suncatcher is a simple, conical solar concentrating device that captures light entering clerestory windows and directs it onto thermal storage elements at the back of a south facing living space. The cone shape and inclination are designed to capture low angle winter sunlight and to reflect away higher angle summer sunlight. It is found that winter radiation through a Suncatcher window is 40 to 50% higher than through an ordinary window, and that the average solar fraction is 59%. Water-filled steal culvert pipes used for thermal storage are found to undergo less stratification, and thus to be more effective, when located where sunlight strikes the bottom rather than the top. Five Suncatcher buildings are described. Designs are considered for 32/sup 0/, 40/sup 0/ and 48/sup 0/ north latitude, and as the latitude increases, the inclination angle of the cone should be lowered. The Cool Pool is an evaporating, shaded roof pond which thermosiphons cool water into water-filled columns within a building. Preliminary experiments indicate that the best shade design has unimpeded north sky view, good ventilation, complete summer shading, a low architectural profile, and low cost attic vent lowers work. Another series of experiments established the satisfactory performance of the Cool Pool on a test building using four water-filled cylinders, two cylinders, and two cylinders connected to the Cool Pool through a heat exchanger. Although an unshaded pool cools better at night than a shaded one, daytime heat gain far offsets this advantage. A vinyl waterbag heat exchanger was developed for use with the Cool Pool. (LEW)

Performance test of solar-assisted ejector cooling system

KAUST Repository

Huang, Bin-Juine

2014-03-01

A solar-assisted ejector cooling/heating system (SACH-2k) is built and test result is reported. The solar-driven ejector cooling system (ECS) is connected in series with an inverter-type air conditioner (IAC). Several advanced technologies are developed in SACH-k2, including generator liquid level control in ECS, the ECS evaporator temperature control, and optimal control of fan power in cooling tower of ECS. From the field test results, the generator liquid level control performs quite well and keeps stable performance of ejector. The ECS evaporator temperature control also performs satisfactorily to keep ejector performance normally under low or fluctuating solar radiation. The fan power control system cooling tower performs stably and reduces the power consumption dramatically without affecting the ECS performance. The test results show that the overall system COPo including power consumptions of peripheral increases from 2.94-3.3 (IAC alone) to 4.06-4.5 (SACH-k2), about 33-43%. The highest COPo is 4.5. © 2013 Elsevier Ltd and IIR. All rights reserved.

Proceedings: Cooling tower and advanced cooling systems conference

International Nuclear Information System (INIS)

1995-02-01

This Cooling Tower and Advanced Cooling Systems Conference was held August 30 through September 1, 1994, in St. Petersburg, Florida. The conference was sponsored by the Electric Power Research Institute (EPRI) and hosted by Florida Power Corporation to bring together utility representatives, manufacturers, researchers, and consultants. Nineteen technical papers were presented in four sessions. These sessions were devoted to the following topics: cooling tower upgrades and retrofits, cooling tower performance, cooling tower fouling, and dry and hybrid systems. On the final day, panel discussions addressed current issues in cooling tower operation and maintenance as well as research and technology needs for power plant cooling. More than 100 people attended the conference. This report contains the technical papers presented at the conference. Of the 19 papers, five concern cooling tower upgrades and retrofits, five to cooling tower performance, four discuss cooling tower fouling, and five describe dry and hybrid cooling systems. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database

Radiation Dose Assessment For The Biota Of Terrestrial Ecosystems In The Shoreline Zone Of The Chernobyl Nuclear Power Plant Cooling Pond

International Nuclear Information System (INIS)

Farfan, E.; Jannik, T.

2011-01-01

Radiation exposure of the biota in the shoreline area of the Chernobyl Nuclear Power Plant Cooling Pond was assessed to evaluate radiological consequences from the decommissioning of the Cooling Pond. The article addresses studies of radioactive contamination of the terrestrial faunal complex and radionuclide concentration ratios in bodies of small birds, small mammals, amphibians, and reptiles living in the area. The data were used to calculate doses to biota using the ERICA Tool software. Doses from 90 Sr and 137 Cs were calculated using the default parameters of the ERICA Tool and were shown to be consistent with biota doses calculated from the field data. However, the ERICA dose calculations for plutonium isotopes were much higher (2-5 times for small mammals and 10-14 times for birds) than the doses calculated using the experimental data. Currently, the total doses for the terrestrial biota do not exceed maximum recommended levels. However, if the Cooling Pond is allowed to drawdown naturally and the contaminants of the bottom sediments are exposed and enter the biological cycle, the calculated doses to biota may exceed the maximum recommended values. The study is important in establishing the current exposure conditions such that a baseline exists from which changes can be documented following the lowering of the reservoir water. Additionally, the study provided useful radioecological data on biota concentration ratios for some species that are poorly represented in the literature.

Active noise canceling system for mechanically cooled germanium radiation detectors

Science.gov (United States)

Nelson, Karl Einar; Burks, Morgan T

2014-04-22

A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

RRTM: A rapid radiative transfer model

Energy Technology Data Exchange (ETDEWEB)

Mlawer, E.J.; Taubman, S.J.; Clough, S.A. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States)

1996-04-01

A rapid radiative transfer model (RRTM) for the calculation of longwave clear-sky fluxes and cooling rates has been developed. The model, which uses the correlated-k method, is both accurate and computationally fast. The foundation for RRTM is the line-by-line radiative transfer model (LBLRTM) from which the relevant k-distributions are obtained. LBLRTM, which has been extensively validated against spectral observations e.g., the high-resolution sounder and the Atmospheric Emitted Radiance Interferometer, is used to validate the flux and cooling rate results from RRTM. Validations of RRTM`s results have been performed for the tropical, midlatitude summer, and midlatitude winter atmospheres, as well as for the four Intercomparison of Radiation Codes in Climate Models (ICRCCM) cases from the Spectral Radiance Experiment (SPECTRE). Details of some of these validations are presented below. RRTM has the identical atmospheric input module as LBLRTM, facilitating intercomparisons with LBLRTM and application of the model at the Atmospheric Radiation Measurement Cloud and Radiation Testbed sites.

46 CFR 190.20-50 - Heating and cooling.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Heating and cooling. 190.20-50 Section 190.20-50... CONSTRUCTION AND ARRANGEMENT Accomodations for Officers, Crew, and Scientific Personnel § 190.20-50 Heating and... the space. (b) Radiators and other heating apparatus must be so placed and shielded, where necessary...

Is cold better ? - exploring the feasibility of liquid-helium-cooled optics

International Nuclear Information System (INIS)

Assoufid, L.; Mills, D.; Macrander, A.; Tajiri, G.

1999-01-01

Both simulations and recent experiments conducted at the Advanced Photon Source showed that the performance of liquid-nitrogen-cooled single-silicon crystal monochromators can degrade in a very rapid nonlinear fashion as the power and for power density is increased. As a further step towards improving the performance of silicon optics, we propose cooling with liquid helium, which dramatically improves the thermal properties of silicon beyond that of liquid nitrogen and brings the performance of single silicon-crystal-based synchrotrons radiation optics up to the ultimate limit. The benefits of liquid helium cooling as well as some of the associated technical challenges will be discussed, and results of thermal and structural finite elements simulations comparing the performance of silicon monochromators cooled with liquid nitrogen and helium will be given

Improvements in liquid metal cooled nuclear reactors

International Nuclear Information System (INIS)

Barnes, S.

1980-01-01

A concrete containment vault for a liquid metal cooled nuclear reactor is described which is lined with thermal insulation to protect the vault against heat radiated from the reactor during normal operation of the reactor but whose efficiency of heat insulation is reduced in an emergency to enable excessive heat from the reactor to be dissipated through the vault. (UK)

Cooled solar PV panels for output energy efficiency optimisation

International Nuclear Information System (INIS)

Peng, Zhijun; Herfatmanesh, Mohammad R.; Liu, Yiming

2017-01-01

Highlights: • Effects of cooling on solar PV performance have been experimentally investigated. • As a solar panel is cooled down, the electric output can have significant increase. • A cooled solar PV system has been proposed for resident application. • Life cycle assessment suggests the cost payback time of cooled PV can be reduced. - Abstract: As working temperature plays a critical role in influencing solar PV’s electrical output and efficacy, it is necessary to examine possible way for maintaining the appropriate temperature for solar panels. This research is aiming to investigate practical effects of solar PV surface temperature on output performance, in particular efficiency. Experimental works were carried out under different radiation condition for exploring the variation of the output voltage, current, output power and efficiency. After that, the cooling test was conducted to find how much efficiency improvement can be achieved with the cooling condition. As test results show the efficiency of solar PV can have an increasing rate of 47% with the cooled condition, a cooling system is proposed for possible system setup of residential solar PV application. The system performance and life cycle assessment suggest that the annual PV electric output efficiencies can increase up to 35%, and the annual total system energy efficiency including electric output and hot water energy output can increase up to 107%. The cost payback time can be reduced to 12.1 years, compared to 15 years of the baseline of a similar system without cooling sub-system.

Experimental investigation of a solar adsorption chiller used for grain depot cooling

International Nuclear Information System (INIS)

Luo, H.L.; Dai, Y.J.; Wang, R.Z.; Wu, J.Y.; Xu, Y.X.; Shen, J.M.

2006-01-01

The solar cooling technology is attractive since cooling load of building is roughly in phase with solar energy availability. In this study, a solar adsorption chiller was built and tested with aim of developing an alternative refrigeration system used for grain cooling storage. This solar adsorption chiller consists of four subsystems, namely, a solar water heating unit with 49.4 m 2 solar collecting area, a silica gel-water adsorption chiller, a cooling tower and a fan coil unit. In order to achieve continuous refrigeration, two adsorption units are operated out-of-phase with mass recovery cycle in the adsorption chiller. Field test results show that, under the climatic conditions of daily solar radiation being about 16-21 MJ/m 2 , this solar adsorption chiller can furnish 14-22 deg. C chilled air with an average cooling output ranging from about 3.2-4.4 kW, its daily solar cooling COP (coefficient of performance) is about 0.1-0.13

Analytical characterization of three cathinone derivatives, 4-MPD, 4F-PHP and bk-EPDP, purchased as bulk powder from online vendors.

Science.gov (United States)

Apirakkan, Orapan; Frinculescu, Anca; Shine, Trevor; Parkin, Mark C; Cilibrizzi, Agostino; Frascione, Nunzianda; Abbate, Vincenzo

2018-02-01

Novel emerging drugs of abuse, also referred as new psychoactive substances, constitute an ever-changing mixture of chemical compounds designed to circumvent legislative controls by means of chemical modifications of previously banned recreational drugs. One such class, synthetic cathinones, namely β-keto derivatives of amphetamines, has been largely abused over the past decade. A number of new synthetic cathinones are detected each year, either in bulk powders/crystals or in biological matrices. It is therefore important to continuously monitor the supply of new synthetic derivatives and promptly report them. By using complementary analytical techniques (i.e. one- and two-dimensional NMR, FT-IR, GC-MS, HRMS and HPLC-UV), this study investigates the detection, identification and full characterization of 1-(4-methylphenyl)-2-(methylamino)pentanone (4-methylpentedrone, 4-MPD), 1-(4-fluorophenyl)-2-(pyrrolidin-1-yl)hexanone (4F-PHP) and 1-(1,3-benzodioxol-5-yl)-2-(ethylamino)-1-pentanone (bk-EPDP), three emerging cathinone derivatives. Copyright © 2017 John Wiley & Sons, Ltd.

Rotational Laser Cooling of Vibrationally and Translationally Cold Molecular Ions

DEFF Research Database (Denmark)

Drewsen, Michael

2011-01-01

[7,8,9]. Furthermore, in order to learn more about the chemistry in interstellar clouds, astrochemists can benefit greatly from direct measurements on cold reactions in laboratories [9]. Working with MgH+ molecular ions in a linear Paul trap, we routinely cool their translational degree of freedom...... by sympathetic cooling with Doppler laser cooled Mg+ ions. Giving the time for the molecules to equilibrate internally to the room temperature blackbody radiation, the vibrational degree of freedom will freeze out, leaving only the rotational degree of freedom to be cooled. We report here on the implementation...... results imply that, through this technique, cold molecular-ion experiments can now be carried out at cryogenic temperatures in room-temperature set-ups. References [1] Koelemeij, J. C. J., Roth, B., Wicht, A., Ernsting, I. and Schiller, S., Phys. Rev. Lett. 98, 173002 (2007). [2] Hudson, J. J., Sauer, B...

Flow distribution analysis on the cooling tube network of ITER thermal shield

International Nuclear Information System (INIS)

Nam, Kwanwoo; Chung, Wooho; Noh, Chang Hyun; Kang, Dong Kwon; Kang, Kyoung-O; Ahn, Hee Jae; Lee, Hyeon Gon

2014-01-01

Thermal shield (TS) is to be installed between the vacuum vessel or the cryostat and the magnets in ITER tokamak to reduce the thermal radiation load to the magnets operating at 4.2K. The TS is cooled by pressurized helium gas at the inlet temperature of 80K. The cooling tube is welded on the TS panel surface and the composed flow network of the TS cooling tubes is complex. The flow rate in each panel should be matched to the thermal design value for effective radiation shielding. This paper presents one dimensional analysis on the flow distribution of cooling tube network for the ITER TS. The hydraulic cooling tube network is modeled by an electrical analogy. Only the cooling tube on the TS surface and its connecting pipe from the manifold are considered in the analysis model. Considering the frictional factor and the local loss in the cooling tube, the hydraulic resistance is expressed as a linear function with respect to mass flow rate. Sub-circuits in the TS are analyzed separately because each circuit is controlled by its own control valve independently. It is found that flow rates in some panels are insufficient compared with the design values. In order to improve the flow distribution, two kinds of design modifications are proposed. The first one is to connect the tubes of the adjacent panels. This will increase the resistance of the tube on the panel where the flow rate is excessive. The other design suggestion is that an orifice is installed at the exit of tube routing where the flow rate is to be reduced. The analysis for the design suggestions shows that the flow mal-distribution is improved significantly

Micromechanical Resonator Driven by Radiation Pressure Force.

Science.gov (United States)

Boales, Joseph A; Mateen, Farrukh; Mohanty, Pritiraj

2017-11-22

Radiation pressure exerted by light on any surface is the pressure generated by the momentum of impinging photons. The associated force - fundamentally, a quantum mechanical aspect of light - is usually too small to be useful, except in large-scale problems in astronomy and astrodynamics. In atomic and molecular optics, radiation pressure can be used to trap or cool atoms and ions. Use of radiation pressure on larger objects such as micromechanical resonators has been so far limited to its coupling to an acoustic mode, sideband cooling, or levitation of microscopic objects. In this Letter, we demonstrate direct actuation of a radio-frequency micromechanical plate-type resonator by the radiation pressure force generated by a standard laser diode at room temperature. Using two independent methods, the magnitude of the resonator's response to forcing by radiation pressure is found to be proportional to the intensity of the incident light.

Microbial analysis of meatballs cooled with vacuum and conventional cooling.

Science.gov (United States)

Ozturk, Hande Mutlu; Ozturk, Harun Kemal; Koçar, Gunnur

2017-08-01

Vacuum cooling is a rapid evaporative cooling technique and can be used for pre-cooling of leafy vegetables, mushroom, bakery, fishery, sauces, cooked food, meat and particulate foods. The aim of this study was to apply the vacuum cooling and the conventional cooling techniques for the cooling of the meatball and to show the vacuum pressure effect on the cooling time, the temperature decrease and microbial growth rate. The results of the vacuum cooling and the conventional cooling (cooling in the refrigerator) were compared with each other for different temperatures. The study shows that the conventional cooling was much slower than the vacuum cooling. Moreover, the microbial growth rate of the vacuum cooling was extremely low compared with the conventional cooling. Thus, the lowest microbial growth occurred at 0.7 kPa and the highest microbial growth was observed at 1.5 kPa for the vacuum cooling. The mass loss ratio for the conventional cooling and vacuum cooling was about 5 and 9% respectively.

Reduction of radiation fields in the cooling water circuits of PWRs: a one-step or a multistep process

International Nuclear Information System (INIS)

Lassau, R.T.; Cherepakhov, G.; Smee, J.L.; Berger, J.

1988-01-01

A basic problem for nuclear power plants is the formation or radioactive corrosion products in crud particles and oxide films found mainly in the primary side of the reactor cooling water circuits. The activated corrosion products produce radiation fields, which are the major source of exposure for personnel during maintenance and operation of the system. As a health safeguard for personnel, and for the considerable economic benefit to a plant that can be realized by the reduction of radiation fields, the nuclear industry implements physical and chemical decontamination methods to dissolve oxide films and to assist in the removal of crud during plant shutdowns. These procedures impact on the scheduling of activities that must be accomplished before the reactor can be returned to full operation and are therefore carefully planned to minimize the time for decontamination while maximizing the radioactive field reductions. Of considerable importance to the industry, therefore, are procedures that might be implemented during normal reactor operation and as a reactor approaches shutdown that would assist in the removal of radioactive material while controlling the recontamination during reactor operation. A study program was therefore undertaken to compare radioactive field reductions and corrosion rates obtained from a dilute multistep chemical decontamination with data obtained from a single-step parametric cycling experiment on PWR materials

Homogenization of some radiative heat transfer models: application to gas-cooled reactor cores; Homogeneisation de modeles de transferts thermiques et radiatifs: application au coeur des reacteurs a caloporteur gaz

Energy Technology Data Exchange (ETDEWEB)

El Ganaoui, K

2006-09-15

In the context of homogenization theory we treat some heat transfer problems involving unusual (according to the homogenization) boundary conditions. These problems are defined in a solid periodic perforated domain where two scales (macroscopic and microscopic) are to be taken into account and describe heat transfer by conduction in the solid and by radiation on the wall of each hole. Two kinds of radiation are considered: radiation in an infinite medium (non-linear problem) and radiation in cavity with grey-diffuse walls (non-linear and non-local problem). The derived homogenized models are conduction problems with an effective conductivity which depend on the considered radiation. Thus we introduce a framework (homogenization and validation) based on mathematical justification using the two-scale convergence method and numerical validation by simulations using the computer code CAST3M. This study, performed for gas cooled reactors cores, can be extended to other perforated domains involving the considered heat transfer phenomena. (author)

Cooling techniques

International Nuclear Information System (INIS)

Moeller, S.P.

1994-01-01

After an introduction to the general concepts of cooling of charged particle beams, some specific cooling methods are discussed, namely stochastic, electron and laser cooling. The treatment concentrates on the physical ideas of the cooling methods and only very crude derivations of cooling times are given. At the end three other proposed cooling schemes are briefly discussed. (orig.)

Radiative budget and cloud radiative effect over the Atlantic from ship-based observations

Directory of Open Access Journals (Sweden)

J. Kalisch

2012-10-01

cooling by 17 W m⁻² compared to the radiation observations. This overestimation in solar cooling is mostly caused by the shortwave impact of convective clouds. The latter show a large overestimation in solar cooling of up to 114 W m⁻². Mean cloud radiative effects of cirrus and stratus clouds were simulated close to the observations.

Heat transfer enhancement in a natural draft dry cooling tower under crosswind operation with heterogeneous water distribution

Energy Technology Data Exchange (ETDEWEB)

Goodarzi, Mohsen; Amooie, Hossein [Bu-Ali Sina Univ., Hamedan (Iran, Islamic Republic of). Dept. of Mechanical Engineering

2016-04-15

Crosswind significantly decreases cooling efficiency of a natural draft dry cooling tower. The possibility of improving cooling efficiency with heterogeneous water distribution within the cooling tower radiators under crosswind condition is analysed. A CFD approach was used to model the flow field and heat transfer phenomena within the cooling tower and airflow surrounding the cooling tower. A mathematical model was developed from various CFD results. Having used a trained Genetic Algorithm with the result of mathematical model, the best water distribution was found among the others. Remodeling the best water distribution with the CFD approach showed that the highest enhancement of the heat transfer compared to the usual uniform water distribution.

Heat transfer enhancement in a natural draft dry cooling tower under crosswind operation with heterogeneous water distribution

International Nuclear Information System (INIS)

Goodarzi, Mohsen; Amooie, Hossein

2016-01-01

Crosswind significantly decreases cooling efficiency of a natural draft dry cooling tower. The possibility of improving cooling efficiency with heterogeneous water distribution within the cooling tower radiators under crosswind condition is analysed. A CFD approach was used to model the flow field and heat transfer phenomena within the cooling tower and airflow surrounding the cooling tower. A mathematical model was developed from various CFD results. Having used a trained Genetic Algorithm with the result of mathematical model, the best water distribution was found among the others. Remodeling the best water distribution with the CFD approach showed that the highest enhancement of the heat transfer compared to the usual uniform water distribution.

Integrative Analysis of Desert Dust Size and Abundance Suggests Less Dust Climate Cooling

Science.gov (United States)

Kok, Jasper F.; Ridley, David A.; Zhou, Qing; Miller, Ron L.; Zhao, Chun; Heald, Colette L.; Ward, Daniel S.; Albani, Samuel; Haustein, Karsten

2017-01-01

Desert dust aerosols affect Earths global energy balance through interactions with radiation, clouds, and ecosystems. But the magnitudes of these effects are so uncertain that it remains unclear whether atmospheric dust has a net warming or cooling effect on global climate. Consequently, it is still uncertain whether large changes in atmospheric dust loading over the past century have slowed or accelerated anthropogenic climate change, and the climate impact of possible future alterations in dust loading is similarly disputed. Here we use an integrative analysis of dust aerosol sizes and abundance to constrain the climatic impact of dust through direct interactions with radiation. Using a combination of observational, experimental, and model data, we find that atmospheric dust is substantially coarser than represented in current climate models. Since coarse dust warms global climate, the dust direct radiative effect (DRE) is likely less cooling than the 0.4 W m superscript 2 estimated by models in a current ensemble. We constrain the dust DRE to -0.20 (-0.48 to +0.20) W m superscript 2, which suggests that the dust DRE produces only about half the cooling that current models estimate, and raises the possibility that dust DRE is actually net warming the planet.

ANISOTROPIC THERMAL CONDUCTION AND THE COOLING FLOW PROBLEM IN GALAXY CLUSTERS

International Nuclear Information System (INIS)

Parrish, Ian J.; Sharma, Prateek; Quataert, Eliot

2009-01-01

We examine the long-standing cooling flow problem in galaxy clusters with three-dimensional magnetohydrodynamics simulations of isolated clusters including radiative cooling and anisotropic thermal conduction along magnetic field lines. The central regions of the intracluster medium (ICM) can have cooling timescales of ∼200 Myr or shorter-in order to prevent a cooling catastrophe the ICM must be heated by some mechanism such as active galactic nucleus feedback or thermal conduction from the thermal reservoir at large radii. The cores of galaxy clusters are linearly unstable to the heat-flux-driven buoyancy instability (HBI), which significantly changes the thermodynamics of the cluster core. The HBI is a convective, buoyancy-driven instability that rearranges the magnetic field to be preferentially perpendicular to the temperature gradient. For a wide range of parameters, our simulations demonstrate that in the presence of the HBI, the effective radial thermal conductivity is reduced to ∼<10% of the full Spitzer conductivity. With this suppression of conductive heating, the cooling catastrophe occurs on a timescale comparable to the central cooling time of the cluster. Thermal conduction alone is thus unlikely to stabilize clusters with low central entropies and short central cooling timescales. High central entropy clusters have sufficiently long cooling times that conduction can help stave off the cooling catastrophe for cosmologically interesting timescales.

Working conditions and health of personnel dealing with ionizing radiation sources

International Nuclear Information System (INIS)

Gus'kova, A.K.

1978-01-01

Analyzed are the results of investigations dedicated to evaluation of working and health conditions of personnel engaged at powerful charged-particle accelerators, in the production of radionuclides, different stages of mining and enrichment of pyrochlore ore, maintenance of radio engineering and radio-physical equipment, those engaged on geological and geophysical research, operators of control desks and apparatuses at nuclear reactors. Observation of separate people has been carried out in control groups numbering 200-250 people. It has been found that the annual levels of irradiation doses are not in excess of maximum permissible doses (MPD), however in cases of long work service the total dose amounts to 150 rem (for 15-20 years). Changes in personnel health conditions are analyzed as dependent on the total irradiation dose. Apart from irradiation, the personnel health is also affected by other factors, specifically: unfavorable meteofactors, working regime etc. Specialized medical control was found to be inexpedient for people whose irradiation level was 1/3 of MPD. However for people whose irradiation level ranges from 1/3 to 1 MPD it is advisable to keep the current volume of oriented medical observation. A special attention in this case should be given to control systems, bronchopulmonary system and the state of cutaneous covering depending on the character of irradiation effects. Problems requiring further comprehensive studies are enumerated

A novel estimation of electrical and cooling losses in electric arc furnaces

International Nuclear Information System (INIS)

Trejo, Eder; Martell, Fernando; Micheloud, Osvaldo; Teng, Lidong; Llamas, Armando; Montesinos-Castellanos, Alejandro

2012-01-01

A method to calculate electrical losses and a heat transfer model of a conventional Electric Arc Furnace (EAF) are presented. The application of a novel power theory for the EAF was used to compute electrical losses and it was compared with conventional power calculations. The electrical losses and electrical variables were used as input parameters to the proposed heat transfer model. Chemical energy sources were included as energy inputs to estimate the overall heat transferred including the heat losses in the cooling system. In the heat transfer model the furnace was divided in 11 inner surfaces and the radiation view factors between them were estimated by a commercial finite element software. Variations of the view factors for different arc coverage were evaluated. Different scenarios for cooling panels losses, with respect to arc coverage and thickness of slag layers adhered to cooling system panels, were analyzed. The approach presented in this work allows calculation of energy balances in electrical arc furnaces with low computational resources. Finally, the contribution of this research work is to define a framework for further research oriented to improve both the electrical and thermal energy efficiencies to increase productivity and reduce energy consumption in steel plants. -- Highlights: ► Radiation view factors for the electric arc furnace are estimated. ► Potential reduction in cooling losses is estimated to be 60 kWh/ton. ► Electrical losses are calculated based in the randomness power theory. ► The new approach yields an increase of 10% in the electrical losses. ► An analytic model is used to estimate the radiation mechanism.

Narrowband solid state vuv coherent source for laser cooling of antihydrogen

Energy Technology Data Exchange (ETDEWEB)

Michan, J. Mario [TRIUMF (Canada); Polovy, Gene; Madison, Kirk W. [The University of British Columbia, Department of Physics and Astronomy (Canada); Fujiwara, Makoto C. [TRIUMF (Canada); Momose, Takamasa, E-mail: momose@chem.ubc.ca [The University of British Columbia, Department of Chemistry, Department of Physics and Astronomy (Canada)

2015-11-15

We describe the design and performance of a solid-state pulsed source of narrowband (< 100 MHz) Lyman-α radiation designed for the purpose of laser cooling magnetically trapped antihydrogen. Our source utilizes an injection seeded Ti:Sapphire amplifier cavity to generate intense radiation at 729.4 nm, which is then sent through a frequency doubling stage and a frequency tripling stage to generate 121.56 nm light. Although the pulse energy at 121.56 nm is currently limited to 12 nJ with a repetition rate of 10 Hz, we expect to obtain greater than 0.1 μJ per pulse at 10 Hz by further optimizing the alignment of the pulse amplifier and the efficiency of the frequency tripling stage. Such a power will be sufficient for cooling a trapped antihydrogen atom from 500 mK to 20mK.

Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

OpenAIRE

Xueping Du; Dongtai Han; Qiangmin Zhu

2018-01-01

To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to e...

Performance of the Conduction-Cooled LDX Levitation Coil

Science.gov (United States)

Michael, P. C.; Schultz, J. H.; Smith, B. A.; Titus, P. H.; Radovinsky, A.; Zhukovsky, A.; Hwang, K. P.; Naumovich, G. J.; Camille, R. J.

2004-06-01

The Levitated Dipole Experiment (LDX) was developed to study plasma confinement in a dipole magnetic field. Plasma is confined in the magnetic field of a 680-kg Nb3Sn Floating Coil (F-coil) that is electromagnetically supported at the center of a 5-m diameter by 3-m tall vacuum chamber. The Levitation Coil (L-coil) is a 2800-turn, double pancake winding that supports the weight of the F-coil and controls its vertical position within the vacuum chamber. The use of high-temperature superconductor (HTS) Bi-2223 for the L-coil minimizes the electrical and cooling power needed for levitation. The L-coil winding pack and support plate are suspended within the L-coil cryostat and cooled by conduction to a single-stage cryocooler rated for 25-W heat load at approximately 20 K. The coil current leads consist of conduction-cooled copper running from room temperature to 80 K and a pair of commercially-available, 150-A HTS leads. An automatically filled liquid-nitrogen reservoir provides cooling for the coil's radiation shield and for the leads' 80-K heat stations. This paper discusses the L-coil system design and its observed cryogenic performance.

Evaporative cooling in ATLAS – present and future

CERN Document Server

Viehhauser, G; The ATLAS collaboration

2010-01-01

Evaporative cooling is gaining interest in the particle physics community, due to the promise of reduced material, good temperature uniformity, and the wide range of temperatures accessible. The largest such system to-date operates in ATLAS, where it removes the heat from the semiconductor detector systems (Silicon strips and pixels). During the installation and commissioning of this system many lessons had to be learned. In parallel we have re-evaluated the requirements for the cooling system, in particular for the evaporation temperature, over the full ATLAS operational lifetime, and can compare them to the real system performance. The critical requirement is for thermal stability at the end of the operation in the high-radiation environment. To predict this we have developed a simple thermal model of the detector modules which yields analytical expressions to evaluate the results of changes in the operating conditions. After a comparison of the revised requirements and the actual present cooling system per...

Enhancing radiative energy transfer through thermal extraction

Directory of Open Access Journals (Sweden)

Tan Yixuan

2016-06-01

Full Text Available Thermal radiation plays an increasingly important role in many emerging energy technologies, such as thermophotovoltaics, passive radiative cooling and wearable cooling clothes [1]. One of the fundamental constraints in thermal radiation is the Stefan-Boltzmann law, which limits the maximum power of far-field radiation to P0 = σT4S, where σ is the Boltzmann constant, S and T are the area and the temperature of the emitter, respectively (Fig. 1a. In order to overcome this limit, it has been shown that near-field radiations could have an energy density that is orders of magnitude greater than the Stefan-Boltzmann law [2-7]. Unfortunately, such near-field radiation transfer is spatially confined and cannot carry radiative heat to the far field. Recently, a new concept of thermal extraction was proposed [8] to enhance far-field thermal emission, which, conceptually, operates on a principle similar to oil immersion lenses and light extraction in light-emitting diodes using solid immersion lens to increase light output [62].Thermal extraction allows a blackbody to radiate more energy to the far field than the apparent limit of the Stefan-Boltzmann law without breaking the second law of thermodynamics.

Apparatus and method for radiation processing of materials

International Nuclear Information System (INIS)

Neuberg, W.B.; Luniewski, R.

1983-01-01

A method and apparatus for radiation degradation processing of polytetrafluoroethylene makes use of a simultaneous irradiation, agitation and cooling. The apparatus is designed to make efficent use of radiation in the processing. (author)

Simultaneous effects of water spray and crosswind on performance of natural draft dry cooling tower

Directory of Open Access Journals (Sweden)

Ahmadikia Hossein

2013-01-01

Full Text Available To investigate the effect of water spray and crosswind on the effectiveness of the natural draft dry cooling tower (NDDCT, a three-dimensional model has been developed. Efficiency of NDDCT is improved by water spray system at the cooling tower entrance for high ambient temperature condition with and without crosswind. The natural and forced heat convection flow inside and around the NDDCT is simulated numerically by solving the full Navier-Stokes equations in both air and water droplet phases. Comparison of the numerical results with one-dimensional analytical model and the experimental data illustrates a well-predicted heat transfer rate in the cooling tower. Applying water spray system on the cooling tower radiators enhances the cooling tower efficiency at both no wind and windy conditions. For all values of water spraying rate, NDDCTs operate most effectively at the crosswind velocity of 3m/s and as the wind speed continues to rise to more than 3 m/s up to 12 m/s, the tower efficiency will decrease by approximately 18%, based on no-wind condition. The heat transfer rate of radiator at wind velocity 10 m/s is 11.5% lower than that of the no wind condition. This value is 7.5% for water spray rate of 50kg/s.

An Anatomy of the 1960s Atlantic Cooling.

Science.gov (United States)

Hodson, Dan; Robson, Jon; Sutton, Rowan

2014-05-01

North Atlantic Sea Surface Temperatures (SSTs) exhibited pronounced multidecadal variability during the 20th Century. In particular, the North Atlantic SSTs exhibited a rapid warming between 1920 and 1940 followed by a rapid cooling between 1960 and 1980. SSTs outside the North Atlantic display a much smaller level of decadal variability over the 20th Century. This pattern of North Atlantic warming and cooling has been linked to subsequent changes in rainfall over the Sahel and Nordeste Brazil, Summertime North American Climate and Atlantic Hurricane Genesis. Several hypotheses for the rapid 1960s Atlantic cooling have been proposed, including a reduction in northward ocean heat transport due to a reduced Atlantic Meridional Overturning Circulation (AMOC) and the significant rise in anthropogenic sulphur dioxide emissions during the latter half of the 20th century. Here we examine the observed 1960s Atlantic cooling in more detail. We describe the evolution of the rapid cooling by constructing a detailed multivariate anatomy of the cooling period in order to illuminate the possible explanations and mechanisms involved. We show that the observed 1960s cooling began around 1964-68 in the Greenland-Iceland-Norway (GIN) seas, later spreading to the Atlantic Sub Polar Gyre and much of the subtropical Atlantic. This initial cooling of the Sub Polar Gyre is associated with a marked reduction in salinity (the Great Salinity Anomaly). The cooling peaked between 1972-76, extending into the Tropical North Atlantic. This period also saw the development of a significant Winter North-South Dipole Mean Sea Level Pressure dipole pattern reminiscent of a positive NAO (High over the Azores, Low over Iceland). The cooling then retreated back to higher latitudes during 1976:80. Our analysis demonstrates that the cooling of the North Atlantic during the 1960s cannot be understood as a simple thermodynamic response to aerosol induced reductions in shortwave radiation. Dynamical changes

Storage vessel for radiation contaminated container

International Nuclear Information System (INIS)

Sakatani, Tadatsugu.

1996-01-01

In a storage vessel of the present invention, a plurality of radiation contaminated material containing bodies are vertically stacked in a cell chamber. Then, the storage vessel comprises a containing tube for containing a plurality of the containing bodies, cooling coils wound around the containing tube, a cooling medium circulating system connected to the cooling coils and circulating cooling medium, and a heat exchanger interposed to the cooling medium circulating system for removing heat of the cooling medium. Heat of the radioactive material containing bodies is transferred to cooling air and cooling coils by way of the container tube, thereby cooling the containing bodies. By the operation of circulating pumps in a cooling medium circulation system, the cooling medium circulates through a circulation channel comprising a cooling medium transfer pipes, cooling medium branching tubes, cooling coils and the heat exchanger, then heat of the cooling medium is transferred to a heat utilizing system by way of the heat exchanger to attain effective utilization of the heat. In this case, heat can be taken out stably even when the storage amount fluctuates and heat releasing amount is reduced, and improvement of heat transfer promotes the cooling of the containing bodies, which enables minimization of the size of the storage vessel. (T.M.)

Regional climate consequences of large-scale cool roof and photovoltaic array deployment

International Nuclear Information System (INIS)

Millstein, Dev; Menon, Surabi

2011-01-01

Modifications to the surface albedo through the deployment of cool roofs and pavements (reflective materials) and photovoltaic arrays (low reflection) have the potential to change radiative forcing, surface temperatures, and regional weather patterns. In this work we investigate the regional climate and radiative effects of modifying surface albedo to mimic massive deployment of cool surfaces (roofs and pavements) and, separately, photovoltaic arrays across the United States. We use a fully coupled regional climate model, the Weather Research and Forecasting (WRF) model, to investigate feedbacks between surface albedo changes, surface temperature, precipitation and average cloud cover. With the adoption of cool roofs and pavements, domain-wide annual average outgoing radiation increased by 0.16 ± 0.03 W m -2 (mean ± 95% C.I.) and afternoon summertime temperature in urban locations was reduced by 0.11-0.53 deg. C, although some urban areas showed no statistically significant temperature changes. In response to increased urban albedo, some rural locations showed summer afternoon temperature increases of up to + 0.27 deg. C and these regions were correlated with less cloud cover and lower precipitation. The emissions offset obtained by this increase in outgoing radiation is calculated to be 3.3 ± 0.5 Gt CO 2 (mean ± 95% C.I.). The hypothetical solar arrays were designed to be able to produce one terawatt of peak energy and were located in the Mojave Desert of California. To simulate the arrays, the desert surface albedo was darkened, causing local afternoon temperature increases of up to + 0.4 deg. C. Due to the solar arrays, local and regional wind patterns within a 300 km radius were affected. Statistically significant but lower magnitude changes to temperature and radiation could be seen across the domain due to the introduction of the solar arrays. The addition of photovoltaic arrays caused no significant change to summertime outgoing radiation when averaged

Defective graphene supported MPd12 (M = Fe, Co, Ni, Cu, Zn, Pd) nanoparticles as potential oxygen reduction electrocatalysts: A first-principles study

KAUST Repository

Liu, Xin

2013-01-24

We studied the electronic structure of MPd12 (M = Fe, Co, Ni, Cu, Zn, Pd) nanoparticles deposited on graphene substrates and their reactivity toward O adsorption, which are directly related to the catalytic performance of these composites in oxygen reduction reaction, by first-principles-based calculations. We found that the alloying between M and Pd can enhance the stability of nanoparticles and promote their oxygen reduction activity to be comparable with that of Pt(111). The defective graphene substrate can provide anchoring sites for these nanoparticles by forming strong metal-substrate interaction. The interfacial interaction can contribute to additional stability and further tune the averaged d-band center of the deposited alloy nanoparticles, resulting in strong interference on the O adsorption. As the O adsorption on these composites is weakened, the oxygen reduction reaction kinetics over these composites will also be promoted. These composites are thus expected to exhibit both high stability and superior catalytic performance in oxygen reduction reaction. © 2013 American Chemical Society.

Acceleration of Cooling of Ice Giants by Condensation in Early Atmospheres

International Nuclear Information System (INIS)

Kurosaki, Kenji; Ikoma, Masahiro

2017-01-01

The present infrared brightness of a planet originates partly from the accretion energy that the planet gained during its formation and hence provides important constraints to the planet formation process. A planet cools down from a hot initial state to the present state by losing energy through radiative emission from its atmosphere. Thus, the atmospheric properties affect the planetary cooling rate. Previous theories of giant planet cooling assume that the atmospheric composition is unchanged throughout the evolution. Planet formation theories, however, suggest that the atmospheres especially of ice giants are rich in heavy elements in the early stages. These heavy elements include condensable species such as H 2 O, NH 3 , and CH 4 , which are expected to have a great impact on atmospheric temperature and thus on radiative emission through latent heat release. In this study we investigate the effect of such condensation on the planetary emission flux and quantify the impact on the cooling timescale. We then demonstrate that the latent heat of these species keeps the atmosphere hot and thus the emission flux high for billions of years, resulting in an acceleration of the cooling of ice giants. This sheds light on the long-standing problem that Uranus is much less bright than theoretically predicted and is different in brightness from Neptune in spite of the similarity in mass and radius. We also find that young ice giants with highly enriched atmospheres are much brighter in the mid-infrared than ice giants with non-enriched atmospheres. This provides important implications for future direct imaging of extrasolar ice giants.

Acceleration of Cooling of Ice Giants by Condensation in Early Atmospheres

Energy Technology Data Exchange (ETDEWEB)

Kurosaki, Kenji; Ikoma, Masahiro, E-mail: kurosaki.k@nagoya-u.jp, E-mail: ikoma@eps.s.u-tokyo.ac.jp [Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2017-06-01

The present infrared brightness of a planet originates partly from the accretion energy that the planet gained during its formation and hence provides important constraints to the planet formation process. A planet cools down from a hot initial state to the present state by losing energy through radiative emission from its atmosphere. Thus, the atmospheric properties affect the planetary cooling rate. Previous theories of giant planet cooling assume that the atmospheric composition is unchanged throughout the evolution. Planet formation theories, however, suggest that the atmospheres especially of ice giants are rich in heavy elements in the early stages. These heavy elements include condensable species such as H{sub 2}O, NH{sub 3}, and CH{sub 4}, which are expected to have a great impact on atmospheric temperature and thus on radiative emission through latent heat release. In this study we investigate the effect of such condensation on the planetary emission flux and quantify the impact on the cooling timescale. We then demonstrate that the latent heat of these species keeps the atmosphere hot and thus the emission flux high for billions of years, resulting in an acceleration of the cooling of ice giants. This sheds light on the long-standing problem that Uranus is much less bright than theoretically predicted and is different in brightness from Neptune in spite of the similarity in mass and radius. We also find that young ice giants with highly enriched atmospheres are much brighter in the mid-infrared than ice giants with non-enriched atmospheres. This provides important implications for future direct imaging of extrasolar ice giants.

Detectors for low energy electron cooling in RHIC

Energy Technology Data Exchange (ETDEWEB)

Carlier, F. S. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2016-02-15

Low-energy operation of RHIC is of particular interest to study the location of a possible critical point in the QCD phase diagram. The performance of RHIC at energies equal to or lower than 10 GV/nucleon is limited by nonlinearities, Intra-BeamScattering (IBS) processes and space-charge effects. To successfully address the luminosity and ion store lifetime limitations imposed by IBS, the method of electron cooling has been envisaged. During electron cooling processes electrons are injected along with the ion beam at the nominal ion bunch velocities. The velocity spread of the ion beam is reduced in all planes through Coulomb interactions between the cold electron beam and the ion beam. The electron cooling system proposed for RHIC will be the first of its kind to use bunched beams for the delivery of the electron bunches, and will therefore be accompanied by the necessary challenges. The designed electron cooler will be located in IP2. The electron bunches will be accelerated by a linac before being injected along side the ion beams. Thirty consecutive electron bunches will be injected to overlap with a single ion bunch. They will first cool the yellow beam before being extracted, turned by 180-degrees, and reinjected into the blue beam for cooling. As such, both the yellow and blue beams will be cooled by the same ion bunches. This will pose considerable challenges to ensure proper electron beam quality to cool the second ion beam. Furthermore, no ondulator will be used in the electron cooler so radiative recombination between the ions and the electrons will occur.

Electron cooling and recombination experiments with an adiabatically expanded electron beam

International Nuclear Information System (INIS)

Pastuszka, S.; Heidelberg Univ.; Schramm, U.; Heidelberg Univ.; Grieser, M.; Heidelberg Univ.; Broude, C.; Heidelberg Univ.; Grimm, R.; Heidelberg Univ.; Habs, D.; Heidelberg Univ.; Kenntner, J.; Heidelberg Univ.; Miesner, H.J.; Heidelberg Univ.; Schuessler, T.; Heidelberg Univ.; Schwalm, D.; Heidelberg Univ.; Wolf, A.; Heidelberg Univ.

1996-01-01

Magnetically guided electron beams with transverse temperatures reduced with respect to the cathode temperature by a factor of more than 7 were realized in the electron cooling device of the heavy-ion storage ring TSR and the effect of the reduced transverse temperature in recombination and electron cooling experiments was studied. Measured dielectronic recombination resonances at low relative energy and spectra of laser-stimulated recombination indicate that transverse electron temperatures of about 17 meV have been obtained at cathode temperatures of about 110 meV. The temperature dependence of the spontaneous electron-ion recombination rate during electron cooling was investigated and found to follow the inverse square-root law expected from the theory of radiative recombination, although the measured absolute rates are higher than predicted. A new method based on analyzing the intensity of the fluorescence light emitted during simultaneous laser and electron cooling is used to measure the longitudinal electron cooling force in a range of relative velocities extending over two orders of magnitude (10 5 -10 7 cm/s). The results confirm the occurrence of 'magnetized electron cooling' also at the reduced transverse temperature and show that, compared to earlier measurements at the high transverse temperature, the cooling force increases by about a factor of 2; a considerably larger increase by a factor of ∼5 would be expected if 'magnetized electron cooling' would not exist. (orig.)

Comparing Social Stories™ to Cool versus Not Cool

Science.gov (United States)

Leaf, Justin B.; Mitchell, Erin; Townley-Cochran, Donna; McEachin, John; Taubman, Mitchell; Leaf, Ronald

2016-01-01

In this study we compared the cool versus not cool procedure to Social Stories™ for teaching various social behaviors to one individual diagnosed with autism spectrum disorder. The researchers randomly assigned three social skills to the cool versus not cool procedure and three social skills to the Social Stories™ procedure. Naturalistic probes…

A photoionization model for the optical line emission from cooling flows

Science.gov (United States)

Donahue, Megan; Voit, G. M.

1991-01-01

The detailed predictions of a photoionization model previously outlined in Voit and Donahue (1990) to explain the optical line emission associated with cooling flows in X-ray emitting clusters of galaxies are presented. In this model, EUV/soft X-ray radiation from condensing gas photoionizes clouds that have already cooled. The energetics and specific consequences of such a model, as compared to other models put forth in the literature is discussed. Also discussed are the consequences of magnetic fields and cloud-cloud shielding. The results illustrate how varying the individual column densities of the ionized clouds can reproduce the range of line ratios observed and strongly suggest that the emission-line nebulae are self-irradiated condensing regions at the centers of cooling flows.

Modeling and performance of the MHTGR [Modular High-Temperature Gas-Cooled Reactor] reactor cavity cooling system

International Nuclear Information System (INIS)

Conklin, J.C.

1990-04-01

The Reactor Cavity Cooling System (RCCS) of the Modular High- Temperature Gas-Cooled Reactor (MHTGR) proposed by the U.S. Department of Energy is designed to remove the nuclear afterheat passively in the event that neither the heat transport system nor the shutdown cooling circulator subsystem is available. A computer dynamic simulation for the physical and mathematical modeling of and RCCS is described here. Two conclusions can be made form computations performed under the assumption of a uniform reactor vessel temperature. First, the heat transferred across the annulus from the reactor vessel and then to ambient conditions is very dependent on the surface emissivities of the reactor vessel and RCCS panels. These emissivities should be periodically checked to ensure the safety function of the RCCS. Second, the heat transfer from the reactor vessel is reduced by a maximum of 10% by the presence of steam at 1 atm in the reactor cavity annulus for an assumed constant in the transmission of radiant energy across the annulus can be expected to result in an increase in the reactor vessel temperature for the MHTGR. Further investigation of participating radiation media, including small particles, in the reactor cavity annulus is warranted. 26 refs., 7 figs., 1 tab

Film cooling for a closed loop cooled airfoil

Science.gov (United States)

Burdgick, Steven Sebastian; Yu, Yufeng Phillip; Itzel, Gary Michael

2003-01-01

Turbine stator vane segments have radially inner and outer walls with vanes extending therebetween. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. At least one film cooling hole is defined through a wall of at least one of the cavities for flow communication between an interior of the cavity and an exterior of the vane. The film cooling hole(s) are defined adjacent a potential low LCF life region, so that cooling medium that bleeds out through the film cooling hole(s) reduces a thermal gradient in a vicinity thereof, thereby the increase the LCF life of that region.

Climate Response to Negative Greenhouse Gas Radiative Forcing in Polar Winter

Science.gov (United States)

Flanner, M. G.; Huang, X.; Chen, X.; Krinner, G.

2018-02-01

Greenhouse gas (GHG) additions to Earth's atmosphere initially reduce global outgoing longwave radiation, thereby warming the planet. In select environments with temperature inversions, however, increased GHG concentrations can actually increase local outgoing longwave radiation. Negative top of atmosphere and effective radiative forcing (ERF) from this situation give the impression that local surface temperatures could cool in response to GHG increases. Here we consider an extreme scenario in which GHG concentrations are increased only within the warmest layers of winter near-surface inversions of the Arctic and Antarctic. We find, using a fully coupled Earth system model, that the underlying surface warms despite the GHG addition exerting negative ERF and cooling the troposphere in the vicinity of the GHG increase. This unique radiative forcing and thermal response is facilitated by the high stability of the polar winter atmosphere, which inhibit thermal mixing and amplify the impact of surface radiative forcing on surface temperature. These findings also suggest that strategies to exploit negative ERF via injections of short-lived GHGs into inversion layers would likely be unsuccessful in cooling the planetary surface.

Thermal analysis of the conduction cooling system for HTS SMES system of 600 kJ class

International Nuclear Information System (INIS)

Hong, Yong Ju; Yeom, Han Kil; Park, Seong Je; Kim, Hyo Bong; Koh, Deuk Yong

2007-01-01

SMES systems need cryogenic cooling systems. Conduction cooling system has more effective, compact structure than cryogen. In general, 2 stage GM cryocoolers are used for conduction cooling of HTS SMES system. 1st stages of cryocoolers are used for the cooling of current leads and radiation shields, and 2nd stages of cryocoolers for HTS coil. For the effective conduction cooling of the HTS SMES system, the temperature difference between the cryocooler and HTS coil should be minimized. In this paper, a cryogenic conduction cooling system for HTS SMES is analyzed to evaluate the performance of the cooling system. The analysis is carried out for the steady state with the heat generation of the HTS coil and effects of the thermal contact resistance. The results show the effects of the heat generation and thermal contact resistance on the temperature distribution

Limits on turbulent propagation of energy in cool-core clusters of galaxies

Science.gov (United States)

Bambic, C. J.; Pinto, C.; Fabian, A. C.; Sanders, J.; Reynolds, C. S.

2018-07-01

We place constraints on the propagation velocity of bulk turbulence within the intracluster medium of three clusters and an elliptical galaxy. Using Reflection Grating Spectrometer measurements of turbulent line broadening, we show that for these clusters, the 90 per cent upper limit on turbulent velocities when accounting for instrumental broadening is too low to propagate energy radially to the cooling radius of the clusters within the required cooling time. In this way, we extend previous Hitomi-based analysis on the Perseus cluster to more clusters, with the intention of applying these results to a future, more extensive catalogue. These results constrain models of turbulent heating in active galactic nucleus feedback by requiring a mechanism which can not only provide sufficient energy to offset radiative cooling but also resupply that energy rapidly enough to balance cooling at each cluster radius.

Cryogen spray cooling during laser tissue welding.

Science.gov (United States)

Fried, N M; Walsh, J T

2000-03-01

Cryogen cooling during laser tissue welding was explored as a means of reducing lateral thermal damage near the tissue surface and shortening operative time. Two centimetre long full-thickness incisions were made on the epilated backs of guinea pigs, in vivo. India ink was applied to the incision edges then clamps were used to appose the edges. A 4 mm diameter beam of 16 W, continuous-wave, 1.06 microm, Nd:YAG laser radiation was scanned over the incisions, producing approximately 100 ms pulses. There was a delay of 2 s between scans. The total irradiation time was varied from 1-2 min. Cryogen was delivered to the weld site through a solenoid valve in spurt durations of 20, 60 and 100 ms. The time between spurts was either 2 or 4 s, corresponding to one spurt every one or two laser scans. Histology and tensile strength measurements were used to evaluate laser welds. Total irradiation times were reduced from 10 min without surface cooling to under 1 min with surface cooling. The thermal denaturation profile showed less denaturation in the papillary dermis than in the mid-dermis. Welds created using optimized irradiation and cooling parameters had significantly higher tensile strengths (1.7 +/- 0.4 kg cm(-2)) than measured in the control studies without cryogen cooling (1.0 +/- 0.2 kg cm(-2)) (p laser welding results in increased weld strengths while reducing thermal damage and operative times. Long-term studies will be necessary to determine weld strengths and the amount of scarring during wound healing.

Active cooling of a mobile phone handset

International Nuclear Information System (INIS)

Grimes, Ronan; Walsh, Ed; Walsh, Pat

2010-01-01

Power dissipation levels in mobile phones continue to increase due to gaming, higher power applications, and increased functionality associated with the internet. The current cooling methodologies of natural convection and radiation limit the power dissipation within a mobile phone to between 1-2 W depending on size. As power dissipation levels increase, products such as mobile phones will require active cooling to ensure that the devices operate within an acceptable temperature envelop from both user comfort and reliability perspectives. In this paper, we focus on the applied thermal engineering problem of an active cooling solution within a typical mobile phone architecture by implementing a custom centrifugal fan within the mobile phone. Its performance is compared in terms of flow rates and pressure drops, allowable phone heat dissipation and maximum phone surface temperature as this is the user constraint for a variety of simulated PCB architectures in the mobile phone. Perforated plates with varying porosity through different size orifices are used to simulate these architectures. The results show that the power level dissipated by a phone for a constant surface temperature may be increased by ∼50 - 75% depending on pressure drop induced by the internal phone architecture. Hence for successful implementation and efficient utilization of active cooling will require chip layout to be considered at the design stage.

Thermoelectric self-cooling for power electronics: Increasing the cooling power

International Nuclear Information System (INIS)

Martinez, Alvaro; Astrain, David; Aranguren, Patricia

2016-01-01

Thermoelectric self-cooling was firstly conceived to increase, without electricity consumption, the cooling power of passive cooling systems. This paper studies the combination of heat pipe exchangers and thermoelectric self-cooling, and demonstrates its applicability to the cooling of power electronics. Experimental tests indicate that source-to-ambient thermal resistance reduces by around 30% when thermoelectric self-cooling system is installed, compared to that of the heat pipe exchanger under natural convection. Neither additional electric power nor cooling fluids are required. This thermal resistance reaches 0.346 K/W for a heat flux of 24.1 kW/m"2, being one order of magnitude lower than that obtained in previous designs. In addition, the system adapts to the cooling demand, reducing this thermal resistance for increasing heat. Simulation tests have indicated that simple system modifications allow relevant improvements in the cooling power. Replacement of a thermoelectric module with a thermal bridge leads to 33.54 kW/m"2 of top cooling power. Likewise, thermoelectric modules with shorter legs and higher number of pairs lead to a top cooling power of 44.17 kW/m"2. These results demonstrate the applicability of thermoelectric self-cooling to power electronics. - Highlights: • Cooling power of passive systems increased. • No electric power consumption. • Applicable for the cooling of power electronics. • Up to 44.17 kW/m"2 of cooling power, one order of magnitude higher. • Source-to-ambient thermal resistance reduces by 30%.

An ion cooling and state characterization apparatus for studies of molecular ion dissociative interactions

International Nuclear Information System (INIS)

Deng, Shihu; Vane, C R; Bannister, M E; Havener, C C; Meyer, F W; Krause, H F; Hettich, R L; Goeringer, D E; Van Berkel, G J

2009-01-01

An experimental capability is being developed at the Oak Ridge National Laboratory Multi-Charged Ion Research Facility (ORNL MIRF) to enable stored cooling and state characterization of molecular ions of essentially any mass. Ions selected from a variety of available sources are injected from the side into a 1.5 meter long electrostatic mirror trap, where excited internal states are cooled by radiative cooling. An electron beam target located near the middle of the ion-trap region, coupled with neutral fragment imaging detector systems at each end of the trap, permits state-specific studies of electron-molecular ion dissociation.

Rotational Laser Cooling of Vibrationally and Translationally Cold Molecular Ions

DEFF Research Database (Denmark)

Drewsen, Michael

2011-01-01

an excellent alternative to atomic qubits in the realization of a practical ion trap based quantum computer due to favourable internal state decoherence rates. In chemistry, state prepared molecular targets are an ideal starting point for uni-molecular reactions, including coherent control...... of photofragmentation through the application of various laser sources [5,6]. In cold bi-molecular reactions, where the effect of even tiny potential barriers becomes significant, experiments with state prepared molecules can yield important information on the details of the potential curves of the molecular complexes...... by sympathetic cooling with Doppler laser cooled Mg+ ions. Giving the time for the molecules to equilibrate internally to the room temperature blackbody radiation, the vibrational degree of freedom will freeze out, leaving only the rotational degree of freedom to be cooled. We report here on the implementation...

Effect of forming temperature conditions on the properties of radiation laced polyethylene films

Energy Technology Data Exchange (ETDEWEB)

Trizno, M S; Gasparyan, K A; Arutyunyan, G V; Borovko, V N

1978-11-01

The effect of radiation lace on the thermomechanical properties of polyethylene films depending on the radiation dose and temperature conditions of their formation was studied. The samples were produced at 160 deg under the pressure of 150 kN/m/sup 2/ with the following cooling in two temperature conditions: 1) cooling of the sample just after pressing in the icy water, and 2) slow cooling of the sample in a press. Films obtained using above conditions were subjected to the radiation lace in the argon medium using ..gamma..-radiation of /sup 60/Co at the exposure dose of 0.8x10/sup 6/ rad/hr. The total radiation dose was from 30 to 200 Mrad. It is shown that the films, obtained under the first cooling conditions have a lower degree of crystallinity. Investigations of gel-fraction content, density, elastic modulus, deformability, modulus of high elasticity, breaking stress, and relative elongation for rupture depending on radiation doze and the degree of crystallinity have shown that minimum degree of crystallinity of initial films provided most uniform adn compact net structure in the laced polyethylene(LP). In this case the material working capacity increases at high temperatures. In order to improve the mechanical properties of LP when exploiting it in the amorphous crystalline state it is recommended to irradiate material with maximum degree of crystallinity.

A parametric study of solar operated cooling system

International Nuclear Information System (INIS)

Zagalei, Abdullatif Salin

2006-01-01

Because of energy for air conditioning has been the fastest-growing segment of energy of consumption market in Libya and generally in north Africa, and with the realization depleting nature of fossil fuel, solar cooling of buildings which leads to the improvement of human comfort represents a potentially significant application of solar energy where the availability of solar radiation meets with the cooling load demand. This application has been shown to be technically feasible but the equipment needs further investigative research to improve its performance and feasibility. A solar operated absorption cooling system with energy storage is selected. A latent heat storage would be a space saver for such application for solar energy. A system modeling is an essential activity in order to go for system simulation. A complete solar cooling system to be modeled through the thermodynamic analysis of each system components. Resulting a package of equations used directly to the system simulation in order to predict the system performance to obtain the optimum working conditions for the selected cooling system. A computer code which is used to simulate a series of calculations was written in Fortran language according to the constructed information flow diagram and simulation program flow char. For a typical input data a set of results are reported and discussed and shows that the selected system promises to be a good choice for air conditioning application in Libya specially for large building as storehouses, shopping centers, public administrative.(Author)

Optimal control and performance test of solar-assisted cooling system

KAUST Repository

Huang, B.J.

2010-10-01

The solar-assisted cooling system (SACH) was developed in the present study. The ejector cooling system (ECS) is driven by solar heat and connected in parallel with an inverter-type air conditioner (A/C). The cooling load can be supplied by the ECS when solar energy is available and the input power of the A/C can be reduced. In variable weather, the ECS will probably operate at off-design condition of ejector and the cooling capability of the ECS can be lost completely. In order to make the ejector operate at critical or non-critical double-choking condition to obtain a better performance, an electronic expansion valve was installed in the suction line of the ejector to regulate the opening of the expansion valve to control the evaporator temperature. This will make the SACH always produce cooling effect even at lower solar radiation periods while the ejector performs at off-design conditions. The energy saving of A/C is experimentally shown 50-70% due to the cooling performance of ECS. The long-term performance test results show that the daily energy saving is around 30-70% as compared to the energy consumption of A/C alone (without solar-driven ECS). The total energy saving of A/C is 52% over the entire test period. © 2010 Elsevier Ltd. All rights reserved.

CHROMOSPHERIC HEATING BY ACOUSTIC WAVES COMPARED TO RADIATIVE COOLING

Energy Technology Data Exchange (ETDEWEB)

Sobotka, M.; Heinzel, P.; Švanda, M.; Jurčák, J. [Astronomical Institute, Academy of Sciences of the Czech Republic (v.v.i.), Fričova 298, 25165 Ondřejov (Czech Republic); Del Moro, D.; Berrilli, F. [Department of Physics, University of Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome (Italy)

2016-07-20

Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of the solar atmosphere. A weak chromospheric plage near the large solar pore NOAA 11005 was observed on 2008 October 15, in the Fe i 617.3 nm and Ca ii 853.2 nm lines of the Interferometric Bidimemsional Spectrometer attached to the Dunn Solar Telescope. In analyzing the Ca ii observations (with spatial and temporal resolutions of 0.″4 and 52 s) the energy deposited by acoustic waves is compared to that released by radiative losses. The deposited acoustic flux is estimated from the power spectra of Doppler oscillations measured in the Ca ii line core. The radiative losses are calculated using a grid of seven one-dimensional hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of the maps of radiative losses and acoustic flux is 72%. In a quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only about 15%. In active areas with a photospheric magnetic-field strength between 300 and 1300 G and an inclination of 20°–60°, the contribution increases from 23% (chromospheric network) to 54% (a plage). However, these values have to be considered as lower limits and it might be possible that the acoustic energy flux is the main contributor to the heating of bright chromospheric network and plages.

A study of cooling time reduction of interferometric cryogenic gravitational wave detectors using a high-emissivity coating

Energy Technology Data Exchange (ETDEWEB)

Sakakibara, Y.; Yamamoto, K.; Chen, D.; Tokoku, C.; Uchiyama, T.; Ohashi, M.; Kuroda, K. [Institute for Cosmic Ray Research (ICRR), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan); Kimura, N.; Suzuki, T.; Koike, S. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2014-01-29

In interferometric cryogenic gravitational wave detectors, there are plans to cool mirrors and their suspension systems (payloads) in order to reduce thermal noise, that is, one of the fundamental noise sources. Because of the large payload masses (several hundred kg in total) and their thermal isolation, a cooling time of several months is required. Our calculation shows that a high-emissivity coating (e.g. a diamond-like carbon (DLC) coating) can reduce the cooling time effectively by enhancing radiation heat transfer. Here, we have experimentally verified the effect of the DLC coating on the reduction of the cooling time.

Properties of solar generators with reflectors and radiators

Science.gov (United States)

Ebeling, W. D.; Rex, D.; Bierfischer, U.

1980-06-01

Radiation cooled concentrator systems using silicon and GaAs cells were studied. The principle of radiation cooling by the reflector surfaces is discussed for cylindrical parabolic reflectors (SARA), truncated hexagonal pyramids, and a small trough configuration. Beam paths, collection properties for imperfect orientation, and thermal optimization parameters were analyzed. The three concentrating systems with radiation cooling offer advantages over the plane panel and over the large trough. With silicon solar cells they exhibit considerably lower solar cell consumption per Kw and also lower mass per kW. With GaAs cells the SARA system reduces the number of solar cells needed per kW to less than 10%. Also in all other cases SARA offers the best values for alpha and F sub sol, as long as narrow angular tolerances of the panel orientation can be met. Analysis of the energy collecting properties for imperfect orientation shows the superiority of the hexagonal concentrator. This device can produce power for even large angles between the sun and the panel normal.

Performance Analysis of Cool Roof, Green Roof and Thermal Insulation on a Concrete Flat Roof in Tropical Climate

OpenAIRE

Zingre, Kishor T.; Yang, Xingguo; Wan, Man Pun

2015-01-01

In the tropics, the earth surface receives abundant solar radiation throughout the year contributing significantly to building heat gain and, thus, cooling demand. An effective method that can curb the heat gains through opaque roof surfaces could provide significant energy savings. This study investigates and compares the effectiveness of various passive cooling techniques including cool roof, green roof and thermal insulation for reducing the heat gain through a flat concrete roof in tropic...

Device and method of cooling control rod drives

International Nuclear Information System (INIS)

Togashi, Hidetoshi; Mase, Noriaki; Matsumura, Yuichi.

1985-01-01

Purpose: To prevent the generation of local temperature rise depending on the reactor core position of the control rod drives and control the temperature to an averaged state in BWR type reactors. Method: Control rod drives having a large charging length of the housing in the pressure vessel involve such a factor that the temperature of the control rod drives is increased by the synergistic effect due to the radiation heat from the reactor core and to the unevenness of the cooling water flow rate, which renders an appropriate temperature control difficult for the reactor core position. A cooling water flow rate controlling device having a restriction mechanism is disposed on the cooling water feed path for each of the hydraulic control units of the control rod drives, so that flow rate to the control rod drives is increased at the center of the reactor core and decreased at the periphery thereof. As a result, average temperature state can be set, temperature increase due to cloggings can be prevented and the thermal effect can be eliminated to thereby improve the reliability. (Moriyama, K.)

Behaviour of organic materials in radiation environment

CERN Document Server

Tavlet, M

2000-01-01

Radiation effects in polymers are reminded together with the ageing factors. Radiation-ageing results are mainly discussed about thermosetting insulators, structural composites and cable-insulating materials. Some hints are given about high-voltage insulations, cooling fluids, organic scintillators and light-guides. Some parameters to be taken into account for the estimate of the lifetime of components in radiation environment are also shown. (23 refs).

Mechanical effects of strong measurement: back-action noise and cooling

Science.gov (United States)

Schwab, Keith

2007-03-01

Our recent experiments show that it is now possible to prepare and measure mechanical systems with thermal occupation factors of N˜25 and perform continuous position measurements close to the limits required by the Heisenberg Uncertainty Principle (1). I will discuss our back-action measurements with nanomechanical structures strongly coupled to single electron transistors. We have been able to observe the stochastic back-action forces exerted by the SET as well as a cooling effect which has analogies to cooling in optical cavities. Furthermore, I will discuss progress using optical fields coupled to mechanical modes which show substantial cooling using the pondermotive effects of the photons impacting a flexible dielectric mirror (2). Both of these techniques pave the way to demonstrating the true quantum properties of a mechanical device: squeezed states, superposition states, and entangled states. (1) ``Quantum Measurement Backaction and Cooling Observed with a Nanomechanical Resonator,'' A. Naik, O. Buu, M.D. LaHaye, M.P. Blencowe, A.D. Armour, A.A. Clerk, K.C. Schwab, Nature 443, 193 (2006). (2) ``Self-cooling of a micro-mirror by radiation pressure,'' S. Gigan, H.R. Boehm, M. Patemostro, F. Blaser, G. Langer, J. Hertzberg, K. Schwab, D. Baeuerle, M. Aspelmeyer, A. Zeilinger, Nature 444, 67 (2006).

Revisiting the Cooling Flow Problem in Galaxies, Groups, and Clusters of Galaxies

Science.gov (United States)

McDonald, M.; Gaspari, M.; McNamara, B. R.; Tremblay, G. R.

2018-05-01

We present a study of 107 galaxies, groups, and clusters spanning ∼3 orders of magnitude in mass, ∼5 orders of magnitude in central galaxy star formation rate (SFR), ∼4 orders of magnitude in the classical cooling rate ({\\dot{M}}cool}\\equiv {M}gas}(rsample, we measure the ICM cooling rate, {\\dot{M}}cool}, using archival Chandra X-ray data and acquire the SFR and systematic uncertainty in the SFR by combining over 330 estimates from dozens of literature sources. With these data, we estimate the efficiency with which the ICM cools and forms stars, finding {ε }cool}\\equiv {SFR}/{\\dot{M}}cool}=1.4 % +/- 0.4% for systems with {\\dot{M}}cool}> 30 M ⊙ yr‑1. For these systems, we measure a slope in the SFR–{\\dot{M}}cool} relation greater than unity, suggesting that the systems with the strongest cool cores are also cooling more efficiently. We propose that this may be related to, on average, higher black hole accretion rates in the strongest cool cores, which could influence the total amount (saturating near the Eddington rate) and dominant mode (mechanical versus radiative) of feedback. For systems with {\\dot{M}}cool}< 30 M ⊙ yr‑1, we find that the SFR and {\\dot{M}}cool} are uncorrelated and show that this is consistent with star formation being fueled at a low (but dominant) level by recycled ISM gas in these systems. We find an intrinsic log-normal scatter in SFR at a fixed {\\dot{M}}cool} of 0.52 ± 0.06 dex (1σ rms), suggesting that cooling is tightly self-regulated over very long timescales but can vary dramatically on short timescales. There is weak evidence that this scatter may be related to the feedback mechanism, with the scatter being minimized (∼0.4 dex) for systems for which the mechanical feedback power is within a factor of two of the cooling luminosity.

Atmospheric transport, clouds and the Arctic longwave radiation paradox

Science.gov (United States)

Sedlar, Joseph

2016-04-01

Clouds interact with radiation, causing variations in the amount of electromagnetic energy reaching the Earth's surface, or escaping the climate system to space. While globally clouds lead to an overall cooling radiative effect at the surface, over the Arctic, where annual cloud fractions are high, the surface cloud radiative effect generally results in a warming. The additional energy input from absorption and re-emission of longwave radiation by the clouds to the surface can have a profound effect on the sea ice state. Anomalous atmospheric transport of heat and moisture into the Arctic, promoting cloud formation and enhancing surface longwave radiation anomalies, has been identified as an important mechanism in preconditioning Arctic sea ice for melt. Longwave radiation is emitted equally in all directions, and changes in the atmospheric infrared emission temperature and emissivity associated with advection of heat and moisture over the Arctic should correspondingly lead to an anomalous signal in longwave radiation at the top of the atmosphere (TOA). To examine the role of atmospheric heat and moisture transport into the Arctic on TOA longwave radiation, infrared satellite sounder observations from AIRS during 2003-2014 are analyzed for summer (JJAS). Thermodynamic metrics are developed to identify months characterized by a high frequency of warm and moist advection into the Arctic, and segregate the 2003-14 time period into climatological and anomalously warm, moist summer months. We find that anomalously warm, moist months result in a significant TOA longwave radiative cooling, which is opposite the forcing signal that the surface experiences during these months. At the timescale of the advective events, 3-10 days, the TOA cooling can be as large as the net surface energy budget during summer. When averaged on the monthly time scale, and over the full Arctic basin (poleward of 75°N), summer months experiencing frequent warm, moist advection events are

Radiative heat transfer in the Na mist dispersion over the hot surface of liquid Na in the cooling system of nuclear reactor

International Nuclear Information System (INIS)

Kunitomo, T.; Shafey, H.M.

1980-01-01

The analysis has been carried out for the radiative heat transfer in the Na mist dispersion enclosed between the hot surface of liquid Na at temperature Tsub(n) and the cold surface of Na deposit at Tsub(c). The model selected for the present study represents the Na mist formed in a sodium cooled fast breeder reactor in which the condensed liquid particles are dispersed in the mixture of the Ar cover gas and the Na vapor. The analysis is based on replacing the inhomogeneous dispersing medium by three discrete homogeneous layers, and formulating the transfer equation for the monochromatic radiation in each layer according to the Chandrasekhar theory. The numerical calculations of the radiative qsub(r) and convective qsub(c) heat transfers have been performed for the wave length range lambda=1.6-30 μm and are compared. The qsub(r) has the same order of magnitude as the qsub(c) for all conditions of the mist dispersions. Both qsub(r) and qsub(c) increase by nearly equal rates with the increase of Tsub(H) and decrease by different rates with increasing Tsub(c). Variations of the particle diameter of the Na mist do not change substantially the qsub(r). Both qsub(r) and qsub(c) decrease slightly with the increase in the total thickness of the Na mist dispersion

A very cool cooling system

CERN Multimedia

Antonella Del Rosso

2015-01-01

The NA62 Gigatracker is a jewel of technology: its sensor, which delivers the time of the crossing particles with a precision of less than 200 picoseconds (better than similar LHC detectors), has a cooling system that might become the precursor to a completely new detector technique.   The 115 metre long vacuum tank of the NA62 experiment. The NA62 Gigatracker (GTK) is composed of a set of three innovative silicon pixel detectors, whose job is to measure the arrival time and the position of the incoming beam particles. Installed in the heart of the NA62 detector, the silicon sensors are cooled down (to about -20 degrees Celsius) by a microfluidic silicon device. “The cooling system is needed to remove the heat produced by the readout chips the silicon sensor is bonded to,” explains Alessandro Mapelli, microsystems engineer working in the Physics department. “For the NA62 Gigatracker we have designed a cooling plate on top of which both the silicon sensor and the...

Comprehensive performance analyses and optimization of the irreversible thermodynamic cycle engines (TCE) under maximum power (MP) and maximum power density (MPD) conditions

International Nuclear Information System (INIS)

Gonca, Guven; Sahin, Bahri; Ust, Yasin; Parlak, Adnan

2015-01-01

This paper presents comprehensive performance analyses and comparisons for air-standard irreversible thermodynamic cycle engines (TCE) based on the power output, power density, thermal efficiency, maximum dimensionless power output (MP), maximum dimensionless power density (MPD) and maximum thermal efficiency (MEF) criteria. Internal irreversibility of the cycles occurred during the irreversible-adiabatic processes is considered by using isentropic efficiencies of compression and expansion processes. The performances of the cycles are obtained by using engine design parameters such as isentropic temperature ratio of the compression process, pressure ratio, stroke ratio, cut-off ratio, Miller cycle ratio, exhaust temperature ratio, cycle temperature ratio and cycle pressure ratio. The effects of engine design parameters on the maximum and optimal performances are investigated. - Highlights: • Performance analyses are conducted for irreversible thermodynamic cycle engines. • Comprehensive computations are performed. • Maximum and optimum performances of the engines are shown. • The effects of design parameters on performance and power density are examined. • The results obtained may be guidelines to the engine designers

Radiation loss driven instabilities in laser heated plasmas

International Nuclear Information System (INIS)

Evans, R.G.

1985-01-01

Any plasma in which a significant part of the power balance is due to optically thin radiative losses may be subject to a radiation cooling instability. A simple analytical model gives the dispersion relation for the instability and inclusion of a realistic radiation loss term in a two dimensional hydrodynamic simulation shows that ''jet'' like features form in moderate to high Z plasmas

Application of PIXE technique to studies on global warming/cooling effect of atmospheric aerosols

International Nuclear Information System (INIS)

Kasahara, M.; Hoeller, R.; Tohno, S.; Onishi, Y.; Ma, C.-J.

2002-01-01

During the last decade, the importance of global warming has been recognized worldwide. Atmospheric aerosols play an important role in the global warming/cooling effects. The physicochemical properties of aerosol particles are fundamental to understanding such effects. In this study, the PIXE technique was applied to measure the average chemical properties of aerosols. Micro-PIXE was also applied to investigate the mixing state of the individual aerosol particle. The chemical composition data were used to estimate the optical properties of aerosols. The average values of aerosol radiative forcing were -1.53 w/m 2 in Kyoto and +3.3 w/m 2 in Nagoya, indicating cooling and warming effects respectively. The difference of radiative forcing in the two cities may be caused by the large difference in chemical composition of aerosols

Passive cooling of standalone flat PV module with cotton wick structures

International Nuclear Information System (INIS)

Chandrasekar, M.; Suresh, S.; Senthilkumar, T.; Ganesh karthikeyan, M.

2013-01-01

Highlights: • A simple passive cooling system is developed for standalone flat PV modules. • 30% Reduction in module temperature is observed with developed cooling system. • 15.61% Increase in output power of PV module is found with developed cooling system. • Module efficiency is increased by 1.4% with cooling arrangement. • Lower thermal degradation due to narrow range of temperature characteristics. - Abstract: In common, PV module converts only 4–17% of the incoming solar radiation into electricity. Thus more than 50% of the incident solar energy is converted as heat and the temperature of PV module is increased. The increase in module temperature in turn decreases the electrical yield and efficiency of the module with a permanent structural damage of the module due to prolonged period of thermal stress (also known as thermal degradation of the module). An effective way of improving efficiency and reducing the rate of thermal degradation of a PV module is to reduce the operating temperature of PV module. This can be achieved by cooling the PV module during operation. Hence in the present work, a simple passive cooling system with cotton wick structures is developed for standalone flat PV modules. The thermal and electrical performance of flat PV module with cooling system consisting of cotton wick structures in combination with water, Al 2 O 3 /water nanofluid and CuO/water nanofluid are investigated experimentally. The experimental results are also compared with the thermal and electrical performance of flat PV module without cooling system

Investigation of Absorption Cooling Application Powered by Solar Energy in the South Coast Region of Turkey

Directory of Open Access Journals (Sweden)

Ozgoren M.

2013-04-01

Full Text Available In this study, an absorption system using ammonia-water (NH3-H2O solution has been theoretically examined in order to meet the cooling need of a detached building having 150 m2 floor area for Antalya, Mersin and Mugla provinces in Turkey. Hourly dynamic cooling load capacities of the building were determined by using Radiant Time Series (RTS method in the chosen cities. For the analysis, hourly average meteorological data such as atmospheric air temperature and solar radiation belonging to the years 1998-2008 are used for performance prediction of the proposed system. Thermodynamic relations for each component of absorption cooling system is explained and coefficients of performance of the system are calculated. The maximum daily total radiation data were calculated as 7173 W/m2day on July 15, 7277 W/m2 day on July 19 and 7231 W/m2day on July 19 for Mersin, Antalya and Mugla, respectively on the 23° toward to south oriented panels from horizontal surface. The generator operating temperatures are considered between 90-130°C and the best result for 110°C is found the optimum degree for maximum coefficient of performance (COP values at the highest solar radiation occurred time during the considered days for each province. The COP values varies between 0.521 and 0.530 for the provinces. In addition, absorber and condenser capacities and thermal efficiency for the absorption cooling system were calculated. The necessary evacuated tube collector area for the different provinces were found in the range of 45 m2 to 47 m2. It is shown that although the initial investment cost is higher for the proposed absorption cooling system, it is economically feasible because of its lower annual operation costs and can successfully be operated for the considered provinces.

Cooling atoms with extraresonant stimulated emission below the Doppler limit

International Nuclear Information System (INIS)

Shevy, Y.

1989-01-01

The process of cooling atoms with radiation pressure is well understood in terms of absorption and spontaneous emission of fluorescence photons. This process imposes a lower limit on the minimum equilibrium temperature of laser cooled two level atoms of K b T = ℎΓ 21 /2 (the Doppler limit), where Γ 21 is the excited state decay rate to the ground state. At high laser intensity, it has been demonstrated that the stimulated emission process changes the sign of the force to a heating force at the red side of the atomic resonance and to a cooling force at blue detunings. Although this stimulated force is more efficient than the radiation pressure force, it has been generally accepted that this force cannot lead to lower equilibrium temperatures due to the large heating caused by diffusion of momentum at high intensity. These conclusions are valid only when the sole damping mechanism is the excited state decay to the ground state by spontaneous emission. However, when the atomic system is opened, i.e., is allowed to decay to other levels, or the dipole decay rate is altered by dephasing events, the stimulated force is dramatically modified. Under this conditions the stimulated force can occur at lower laser intensity and can even reverse sign to provide damping at the red side of resonance. These phenomena originate from extraresonances in the stimulated emission process between the two counterpropagating waves. These resonances appear as a dispersive feature in pump probe spectra (Two Wave Mixing) and are closely related to the extraresonances in four wave mixing studied originally by Bloembergen and co-workers. This paper establishes this connection and the potential of these phenomena for laser cooling. The implications of these results to the recently observed ultra-cold Na and Cs atoms are also discussed

Magnetocaloric Effect and Thermoelectric Cooling - A Synergistic Cooling Technology

Science.gov (United States)

2018-01-16

Thermoelectric Cooling - A Synergistic Cooling Technology Sb. GRANT NUMBER N00173-14-1-G016 Sc. PROGRAM ELEMENT NUMBER 82-2020-17 6. AUTHOR(S) 5d...Magnetocaloric Effect and Thermoelectric Cooling - A Synergistic Cooling Technology NRL Grant N00173-14-l-G016 CODE 8200: Spacecraft Engineering Department...82-11-0 1: Space and Space Systems Technology General Engineering & Research, L.L.C. Technical & Administrative point of contact: Dr. Robin

Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

Directory of Open Access Journals (Sweden)

Xueping Du

2018-04-01

Full Text Available To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to evaluate cooling performance. Rotating wind deflectors are adopted to reduce the influence of crosswind on the cooling tower performance. The effects of the rotating wind deflectors on the thermal-hydraulic characteristics of the air-cooling tower under different environmental crosswind speeds are studied. Results indicate that the wind direction in the tower reverses as the rotating speed of the wind deflectors increases. The thermal performance of an air-cooling tower under crosswind conditions can be improved by using rotating wind deflectors. The heat transfer rate of a cooling tower with eight wind deflectors begins to increase when the rotating speed exceeds 2 r/min.

WORKSHOP: Beam cooling

International Nuclear Information System (INIS)

Anon.

1994-01-01

Cooling - the control of unruly particles to provide well-behaved beams - has become a major new tool in accelerator physics. The main approaches of electron cooling pioneered by Gersh Budker at Novosibirsk and stochastic cooling by Simon van der Meer at CERN, are now complemented by additional ideas, such as laser cooling of ions and ionization cooling of muons

Spacesuit Evaporator-Absorber-Radiator (SEAR)

Science.gov (United States)

Hodgson, Ed; Izenson, Mike; Chan, Weibo; Bue, Grant C.

2012-01-01

For decades advanced spacesuit developers have pursued a regenerable, robust nonventing system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s Lithium Chloride Absorber Radiator (LCAR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. This water vapor is then captured by solid LiCl in the LCAR with a high enthalpy of absorption, resulting in sufficient temperature lift to reject heat to space by radiation. After the sortie, the LCAR would be heated up and dried in a regenerator to drive off and recover the absorbed evaporant. A engineering development prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The LCAR was able to stably reject 75 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

A Massive, Cooling-Flow-Induced Starburst in the Core of a Highly Luminous Galaxy Cluster

Science.gov (United States)

McDonald, M.; Bayliss, M.; Benson, B. A.; Foley, R. J.; Ruel, J.; Sullivan, P.; Veilleux, S.; Aird, K. A.; Ashby, M. L. N.; Bautz, M.;

Accident analysis of heat pipe cooled and AMTEC conversion space reactor system

International Nuclear Information System (INIS)

Yuan, Yuan; Shan, Jianqiang; Zhang, Bin; Gou, Junli; Bo, Zhang; Lu, Tianyu; Ge, Li; Yang, Zijiang

2016-01-01

Highlights: • A transient analysis code TAPIRS for HPS has been developed. • Three typical accidents are analyzed using TAPIRS. • The reactor system has the self-stabilization ability under accident conditions. - Abstract: A space power with high power density, light weight, low cost and high reliability is of crucial importance to future exploration of deep space. Space reactor is an excellent candidate because of its unique characteristics of high specific power, low cost, strong environment adaptability and so on. Among all types of space reactors, heat pipe cooled space reactor, which adopts the passive heat pipe (HP) as core cooling component, is considered as one of the most promising choices and is widely studied all over the world. This paper develops a transient analysis code (TAPIRS) for heat pipe cooled space reactor power system (HPS) based on point reactor kinetics model, lumped parameter core heat transfer model, combined HP model (self-diffusion model, flat-front startup model and network model), energy conversion model of Alkali Metal Thermal-to-Electric Conversion units (AMTEC), and HP radiator model. Three typical accidents, i.e., control drum failure, AMTEC failure and partial loss of the heat transfer area of radiator are then analyzed using TAPIRS. By comparing the simulation results of the models and steady state with those in the references, the rationality of the models and the solution method is validated. The results show the following. (1) After the failure of one set of control drums, the reactor power finally reaches a stable value after two local peaks under the temperature feedback. The fuel temperature rises rapidly, however it is still under safe limit. (2) The fuel temperature is below a safe limit under the AMTEC failure and partial loss of the heat transfer area of radiator. This demonstrates the rationality of the system design and the potential applicability of the TAPIRS code for the future engineering application of

ANN based optimization of a solar assisted hybrid cooling system in Turkey

Energy Technology Data Exchange (ETDEWEB)

Ozgur, Arif; Yetik, Ozge; Arslan, Oguz [Mechanical Eng. Dept., Engineering Faculty, Dumlupinar University (Turkey)], email: maozgur@dpu.edu.tr, email: ozgeyetik@dpu.edu.tr, email: oarslan@dpu.edu.tr

2011-07-01

This study achieved optimization of a solar assisted hybrid cooling system with refrigerants such as R717, R141b, R134a and R123 using an artificial neural network (ANN) model based on average total solar radiation, ambient temperature, generator temperature, condenser temperature, intercooler temperature and fluid types. ANN is a new tool; it works rapidly and can thus be a solution for design and optimization of complex power cycles. A unique flexible ANN algorithm was introduced to evaluate the solar ejector cooling systems because of the nonlinearity of neural networks. The conclusion was that the best COPs value obtained with the ANN is 1.35 and COPc is 3.03 when the average total solar radiation, ambient temperature, generator temperature, condenser temperature, intercooler temperature and algorithm are respectively 674.72 W/m2, 17.9, 80, 15 and 13 degree celsius and LM with 14 neurons in single hidden layer, for R717.

Fundamental design bases for independent core cooling in Swedish nuclear power reactors

International Nuclear Information System (INIS)

Jelinek, Tomas

2015-01-01

New regulations on design and construction of nuclear power plants came into force in 2005. The need of an independent core cooling system and if the regulations should include such a requirement was discussed. The Swedish Radiation Safety authority (SSM) decided to not include such a requirement because of open questions about the water balance and started to investigate the consequences of an independent core cooling system. The investigation is now finished and SSM is also looking at the lessons learned from the accident in Fukushima 2011. One of the most important measures in the Swedish national action plan is the implementation of an independent core cooling function for all Swedish power plants. SSM has investigated the basic design criteria for such a function where some important questions are the level of defence in depth and the acceptance criteria. There is also a question about independence between the levels of defence in depth that SSM have included in the criteria. Another issue that has to be taken into account is the complexity of the system and the need of automation where independence and simplicity are very strong criteria. In the beginning of 2014 a memorandum was finalized regarding fundamental design bases for independent core cooling in Swedish nuclear power reactors. A decision based on this memorandum with an implementation plan will be made in the first half of 2014. Sweden is also investigating the possibility to have armed personnel on site, which is not allowed currently. The result from the investigation will have impact on the possibility to use mobile equipment and the level of protection of permanent equipment. In this paper, SSM will present the memorandum for design bases for independent core cooling in Swedish nuclear power reactors that was finalized in March 20147 that also describe SSM's position regarding independence and automation of the independent core cooling function. This memorandum describes the Swedish

Increasing photovoltaic panel power through water cooling technique

Directory of Open Access Journals (Sweden)

Calebe Abrenhosa Matias

2017-02-01

Full Text Available This paper presents the development of a cooling apparatus using water in a commercial photovoltaic panel in order to analyze the increased efficiency through decreased operating temperature. The system enables the application of reuse water flow, at ambient temperature, on the front surface of PV panel and is composed of an inclined plane support, a perforated aluminum profile and a water gutter. A luminaire was specially developed to simulate the solar radiation over the module under test in a closed room, free from the influence of external climatic conditions, to carry out the repetition of the experiment in controlled situations. The panel was submitted to different rates of water flow. The best water flow rate was of 0.6 L/min and net energy of 77.41Wh. Gain of 22.69% compared to the panel without the cooling system.

Neutron spectrometry by diamond detector for nuclear radiation

International Nuclear Information System (INIS)

Kozlov, S.F.; Konorova, E.A.; Barinov, A.L.; Jarkov, V.P.

1975-01-01

Experiments on fast neutron spectrometry using the nuclear radiation diamond detector inside a horizontal channel of a water-cooled and water-moderated reactor are described. It is shown that the diamond detector enables neutron spectra to be measured within the energy range of 0.3 to 10 MeV against reactor gamma-radiation background and has radiation resistance higher than that of conventional semiconductor detectors. (U.S.)

Experimental evaluation of cooling efficiency of the high performance cooling device

Science.gov (United States)

Nemec, Patrik; Malcho, Milan

2016-06-01

This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W.

Experimental evaluation of cooling efficiency of the high performance cooling device

Energy Technology Data Exchange (ETDEWEB)

Nemec, Patrik, E-mail: patrik.nemec@fstroj.uniza.sk; Malcho, Milan, E-mail: milan.malcho@fstroj.uniza.sk [University of Žilina, Faculty of Mechanical Engineering, Department of Power Engineering, Univerzitna 1, 010 26 Žilina (Slovakia)

2016-06-30

This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W.

Method of lightening radiation darkened optical elements

International Nuclear Information System (INIS)

Reich, F.R.; Schwankoff, A.R.

1980-01-01

A method of lightening a radiation-darkened optical element in which visible optical energy or electromagnetic radiation having a wavelength in the range of from about 2000 to about 20,000 angstroms is directed into the radiation-darkened optical element; the method may be used to lighten radiation-darkened optical element in-situ during the use of the optical element to transmit data by electronically separating the optical energy from the optical output by frequency filtering, data cooling, or interlacing the optic energy between data intervals

Physical installation of Pelletron and electron cooling system

International Nuclear Information System (INIS)

Hurh, P.

1997-01-01

Bremsstrahlung of 5 MeV electrons at a loss current of 50 microamp in the acceleration region is estimated to produce X-ray intensities of 7 Rad/sec. Radiation losses due to a misteer or sudden obstruction will of course be much higher still (estimated at 87,500 Rad/hr for a 0.5 mA beam current). It is estimated that 1.8 meters of concrete will be necessary to adequately shield the surrounding building areas at any possible Pelletron installation site. To satisfy our present electron cooling development plan, two Pelletron installations are required, the first at our development lab in the Lab B/NEF Enclosure area and the second at the operational Main Injector service building, MI-30, in the main Injector ring. The same actual Pelletron and electron beam-line components will be used at both locations. The Lab B installation will allow experimentation with actual high energy electron beam to develop the optics necessary for the cooling straight while Main Injector/Recycler commissioning is taking place. The MI-30 installation is obviously the permanent home for the Pelletron when electron cooling becomes operational. Construction plans for both installations will be discussed here

Cooling towers

International Nuclear Information System (INIS)

Boernke, F.

1975-01-01

The need for the use of cooling systems in power plant engineering is dealt with from the point of view of a non-polluting form of energy production. The various cooling system concepts up to the modern natural-draught cooling towers are illustrated by examples. (TK/AK) [de

Water-Cooled Data Center Packs More Power Per Rack | Poster

Science.gov (United States)

By Frank Blanchard and Ken Michaels, Staff Writers Behind each tall, black computer rack in the data center at the Advanced Technology Research Facility (ATRF) is something both strangely familiar and oddly out of place: It looks like a radiator. The back door of each cabinet is gridded with the coils of the Liebert cooling system, which circulates chilled water to remove heat

Mechanical and experimental study on freeze proof solar powered adsorption cooling tube using active carbon/methanol working pair

International Nuclear Information System (INIS)

Zhao Huizhong; Zhang Min; Liu Zhenyan; Liu Yanling; Ma Xiaodong

2008-01-01

The freeze proof solar cooling tube, which can produce cooling capacity with the refrigerant temperature below 0 deg. C using solar light as energy and active carbon-methanol as working pair, was firstly designed and made in this research. This paper focused on mechanical and experimental study on a freeze proof solar powered adsorption cooling tube. The following experimental results could be concluded: at the solar radiation value between 15.3 and 17.1 MJ m -2 , the highest adsorbent bed temperature is below 110 deg. C. The freeze proof solar cooling tube's cooling capacity was about 87-99 kJ, and the coefficient of performance (COP) was more than 0.11 when the evaporation temperature was about -4 deg. C

Parametric feedback cooling of a single atom inside on optical cavity

International Nuclear Information System (INIS)

Tatjana Wilk

2014-01-01

An optical cavity can be used as a kind of intensifier to study radiation features of an atom, which are hard to detect in free space, like squeezing. Such experiments make use of strong coupling between atom and cavity mode, which experimentally requires the atom to be well localized in the cavity mode. This can be achieved using feedback on the atomic motion: from intensity variations of a probe beam transmitted through the cavity information about the atomic motion is gained, which is used to synchronously modulate the trapping potential holding the atom, leading to cooling and better localization. Here, we report on efficient parametric feedback cooling of a single atom held in an intra-cavity standing wave dipole trap. In contrast to previous feedback strategies, this scheme cools the fast axial oscillation of the atom as well as the slower radial motion. (author)

A simple approach to CO cooling in molecular clouds

Science.gov (United States)

Whitworth, A. P.; Jaffa, S. E.

2018-03-01

Carbon monoxide plays an important role in interstellar molecular clouds, both as a coolant, and as a diagnostic molecule. However, a proper evaluation of the cooling rate due to CO requires a determination of the populations of many levels, the spontaneous and stimulated radiative de-excitation rates between these levels, and the transfer of the emitted multi-line radiation; additionally, this must be done for three isotopologues. It would be useful to have a simple analytic formulation that avoided these complications and the associated computational overhead; this could then be used in situations where CO plays an important role as a coolant, but the details of this role are not the main concern. We derive such a formulation here, by first considering the two asymptotic forms that obtain in the limits of (a) low volume-density and optical depth, and (b) high volume-density and optical depth. These forms are then combined in such a way as to fit the detailed numerical results from Goldsmith & Langer (1978, ApJ, 222, 881; hereafter GL78). The GL78 results cover low temperatures, and a range of physical conditions where the interplay of thermal and sub-thermal excitation, optical-depth effects, and the contributions from rare isotopologues, are all important. The fit is obtained using the Metropolis-Hastings method, and reproduces the results of GL78 well. It is a purely local and analytic function of state — specifically a function of the density, ρ, isothermal sound speed, a, CO abundance, XCO, and velocity divergence, ∇ṡυ. As an illustration of its use, we consider the cooling layer following a slow steady non-magnetic planar J-shock. We show that, in this idealised configuration, if the post-shock cooling is dominated by CO and its isotopologues, the thickness of the post-shock cooling layer is very small and approximately independent of the pre-shock velocity, υo, or pre-shock isothermal sound speed, ao.

Reduced cooling following future volcanic eruptions

Science.gov (United States)

Hopcroft, Peter O.; Kandlbauer, Jessy; Valdes, Paul J.; Sparks, R. Stephen J.

2017-11-01

Volcanic eruptions are an important influence on decadal to centennial climate variability. Large eruptions lead to the formation of a stratospheric sulphate aerosol layer which can cause short-term global cooling. This response is modulated by feedback processes in the earth system, but the influence from future warming has not been assessed before. Using earth system model simulations we find that the eruption-induced cooling is significantly weaker in the future state. This is predominantly due to an increase in planetary albedo caused by increased tropospheric aerosol loading with a contribution from associated changes in cloud properties. The increased albedo of the troposphere reduces the effective volcanic aerosol radiative forcing. Reduced sea-ice coverage and hence feedbacks also contribute over high-latitudes, and an enhanced winter warming signal emerges in the future eruption ensemble. These findings show that the eruption response is a complex function of the environmental conditions, which has implications for the role of eruptions in climate variability in the future and potentially in the past.

Radiation protection training for personnel at light-water-cooled nuclear power plants

International Nuclear Information System (INIS)

Anon.

1981-01-01

Section 19.12 Instructions to Workers, of 10 CFR Part 19, Notices, Instructions, and Reports to Workers; Inspections, requires that individuals be given instruction in radiation protection that is commensurate with the potential radiation protection problems they may encounter in restricted areas as defined in para. 19.3(e) of 10 CFR Part 19. Para. 20.1(c) of 10 CFR Part 20, Standards for Protection Against Radiation, states that occupational radiation exposure should be kept as low as is reasonably achievable (ALARA). Appropriate training is an essential aspect of an ALARA program. This guide describes a radiation protection training program consistent with the ALARA objective and acceptable to the NRC staff for meeting the training requirements of 10 CFR Part 19 with respect to individuals that enter restricted areas at nuclear power plants

Restaurant food cooling practices.

Science.gov (United States)

Brown, Laura Green; Ripley, Danny; Blade, Henry; Reimann, Dave; Everstine, Karen; Nicholas, Dave; Egan, Jessica; Koktavy, Nicole; Quilliam, Daniela N

2012-12-01

Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention's Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study.

Restaurant Food Cooling Practices†

Science.gov (United States)

BROWN, LAURA GREEN; RIPLEY, DANNY; BLADE, HENRY; REIMANN, DAVE; EVERSTINE, KAREN; NICHOLAS, DAVE; EGAN, JESSICA; KOKTAVY, NICOLE; QUILLIAM, DANIELA N.

2017-01-01

Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention’s Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study. PMID:23212014

Cooling tower calculations

International Nuclear Information System (INIS)

Simonkova, J.

1988-01-01

The problems are summed up of the dynamic calculation of cooling towers with forced and natural air draft. The quantities and relations are given characterizing the simultaneous exchange of momentum, heat and mass in evaporative water cooling by atmospheric air in the packings of cooling towers. The method of solution is clarified in the calculation of evaporation criteria and thermal characteristics of countercurrent and cross current cooling systems. The procedure is demonstrated of the calculation of cooling towers, and correction curves and the effect assessed of the operating mode at constant air number or constant outlet air volume flow on their course in ventilator cooling towers. In cooling towers with the natural air draft the flow unevenness is assessed of water and air relative to its effect on the resulting cooling efficiency of the towers. The calculation is demonstrated of thermal and resistance response curves and cooling curves of hydraulically unevenly loaded towers owing to the water flow rate parameter graded radially by 20% along the cross-section of the packing. Flow rate unevenness of air due to wind impact on the outlet air flow from the tower significantly affects the temperatures of cooled water in natural air draft cooling towers of a design with lower demands on aerodynamics, as early as at wind velocity of 2 m.s -1 as was demonstrated on a concrete example. (author). 11 figs., 10 refs

Classical entropy generation analysis in cooled homogenous and functionally graded material slabs with variation of internal heat generation with temperature, and convective–radiative boundary conditions

International Nuclear Information System (INIS)

Torabi, Mohsen; Zhang, Kaili

2014-01-01

This article investigates the classical entropy generation in cooled slabs. Two types of materials are assumed for the slab: homogeneous material and FGM (functionally graded material). For the homogeneous material, the thermal conductivity is assumed to be a linear function of temperature, while for the FGM slab the thermal conductivity is modeled to vary in accordance with the rule of mixtures. The boundary conditions are assumed to be convective and radiative concurrently, and the internal heat generation of the slab is a linear function of temperature. Using the DTM (differential transformation method) and resultant temperature fields from the DTM, the local and total entropy generation rates within slabs are derived. The effects of physically applicable parameters such as the thermal conductivity parameter for the homogenous slab, β, the thermal conductivity parameter for the FGM slab, γ, gradient index, j, internal heat generation parameter, Q, Biot number at the right side, Nc 2 , conduction–radiation parameter, Nr 2 , dimensionless convection sink temperature, δ, and dimensionless radiation sink temperature, η, on the local and total entropy generation rates are illustrated and explained. The results demonstrate that considering temperature- or coordinate-dependent thermal conductivity and radiation heat transfer at both sides of the slab have great effects on the entropy generation. - Highlights: • The paper investigates entropy generation in a slab due to heat generation and convective–radiative boundary conditions. • Both homogeneous material and FGM (functionally graded material) were considered. • The calculations are carried out using the differential transformation method which is a well-tested analytical technique

Blackbody Radiation from Isolated Neptunes

Science.gov (United States)

Ginzburg, Sivan; Sari, Re'em; Loeb, Abraham

2016-05-01

Recent analyses of the orbits of some Kuiper belt objects hypothesize the presence of an undiscovered Neptune-size planet at a very large separation from the Sun. The energy budget of Neptunes on such distant orbits is dominated by the internal heat released by their cooling rather than solar irradiation (making them effectively “isolated”). The blackbody radiation that these planets emit as they cool may provide the means for their detection. Here, we use an analytical toy model to study the cooling and radiation of isolated Neptunes. This model can translate a detection (or a null detection) to a constraint on the size and composition of the hypothesized “Planet Nine.” Specifically, the thick gas atmosphere of Neptune-like planets serves as an insulating blanket that slows down their cooling. Therefore, a measurement of the blackbody temperature, {T}{{eff}}˜ 50 {{K}}, at which a Neptune emits, can be used to estimate the mass of its atmosphere, {M}{{atm}}. Explicitly, we find the relation {T}{{eff}}\\propto {M}{{atm}}1/12. Despite this weak relation, a measurement of the flux at the Wien tail can constrain the atmospheric mass, at least to within a factor of a few, and provide useful limits to possible formation scenarios of these planets. Finally, we constrain the size and composition of Planet Nine by combining our model with the null results of recent all-sky surveys.

Thermal and radiation losses in a linear device

International Nuclear Information System (INIS)

Rosenau, P.; Degani, D.

1980-01-01

An analysis is presented of the electron temperature in a linear device which includes the effect of thermal conduction, heat flux limit, radiation, and end plugs. It is found that the thermal conduction and the heat flux limit are dominant in the initial phase of cooling, while the later phase is almost completely controlled by radiation that spatially homogenizes the temperature distribution. In the case of bremsstrahlung, within the frame of the present model, the temperature decays to zero in a finite time. This process takes the form of a cooling wave that moves from the ends of the column to the center. Impurities cause a milder, exponential decay, which is still much faster than the algebraic conduction decay. The thermal effectiveness of the end plugs is described by a convective transfer coefficient h/sub p/. Its scaling law (in terms of the coupled plamsa-plug system) reveals that a very high plug-plasma density ratio provides a simple way to significantly retard the cooling

Experimental results of a direct air-cooled ammonia–lithium nitrate absorption refrigeration system

International Nuclear Information System (INIS)

Llamas-Guillén, S.U.; Cuevas, R.; Best, R.; Gómez, V.H.

2014-01-01

Absorption thermal cooling systems driven by renewable energy are a viable option in order to reduce fossil fuel consumption and the associated emissions. This work shows the results of an air cooled absorption cooling prototype working with an ammonia–lithium nitrate mixture at high ambient temperatures. An absorption refrigeration system was designed and built. The prototype is a one stage ammonia–lithium nitrate air cooled chiller. The experimental system was instrumented to evaluate each component. This paper shows the operation conditions in the experimental unit as well as some of the heat loads encountered at different operating conditions. The system was operated successfully at ambient temperatures in the range of 25–35 °C. A series of test showed that even at ambient temperatures it can be operated at evaporator temperatures below 10 °C producing chilled water for air conditioning applications such as radiative cooling panels. The system proved to stabilize very quickly and no risk of crystallization was encountered so the first results are promising in order to continue with the development of a more advanced prototype. - Highlights: •Experimental results of a direct air-cooled ammonia–lithium nitrate system. •The prototype is a one stage ammonia–lithium nitrate air cooled chiller. •The absorption system was operated successfully at ambient temperatures. •Cooling loads of 4.5 kW were reached in the chilled water side

Cooling Tower Overhaul of Secondary Cooling System in HANARO

Energy Technology Data Exchange (ETDEWEB)

Park, Young Chul; Lee, Young Sub; Jung, Hoan Sung; Lim, In Chul [KAERI, Daejeon (Korea, Republic of)

2007-07-01

HANARO, an open-tank-in-pool type research reactor of 30 MWth power in Korea, has been operating normally since its initial criticality in February, 1995. For the last about ten years, A cooling tower of a secondary cooling system has been operated normally in HANARO. Last year, the cooling tower has been overhauled for preservative maintenance including fills, eliminators, wood support, water distribution system, motors, driving shafts, gear reducers, basements, blades and etc. This paper describes the results of the overhaul. As results, it is confirmed that the cooling tower maintains a good operability through a filed test. And a cooling capability will be tested when a wet bulb temperature is maintained about 28 .deg. C in summer and the reactor is operated with the full power.

Cooling Performance of ALIP according to the Air or Sodium Cooling Type

Energy Technology Data Exchange (ETDEWEB)

Ye, Huee-Youl; Yoon, Jung; Lee, Tae-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

ALIP pumps the liquid sodium by Lorentz force produced by the interaction of induced current in the liquid metal and their associated magnetic field. Even though the efficiency of the ALIP is very low compared to conventional mechanical pumps, it is very useful due to the absence of moving parts, low noise and vibration level, simplicity of flow rate regulation and maintenance, and high temperature operation capability. Problems in utilization of ALIP concern a countermeasure for elevation of internal temperature of the coil due to joule heating and how to increase magnetic flux density of Na channel gap. The conventional ALIP usually used cooling methods by circulating the air or water. On the other hand, GE-Toshiba developed a double stator pump adopting the sodium-immersed self-cooled type, and it recovered the heat loss in sodium. Therefore, the station load factor of the plant could be reduced. In this study, the cooling performance with cooling types of ALIP is analyzed. We developed thermal analysis models to evaluate the cooling performance of air or sodium cooling type of ALIP. The cooling performance is analyzed for operating parameters and evaluated with cooling type. 1-D and 3-D thermal analysis model for IHTS ALIP was developed, and the cooling performance was analyzed for air or sodium cooling type. The cooling performance for air cooling type was better than sodium cooling type at higher air velocity than 0.2 m/s. Also, the air temperature of below 270 .deg. demonstrated the better cooling performance as compared to sodium.

Characterization of ASTM A335 P92 steel in continuous cooling cycles

International Nuclear Information System (INIS)

Xaubet, M. N.; Danón, C. A.; Ramos, C. P.

2013-01-01

The operating conditions demanded by Generation IV reactors include high temperatures, higher radiation doses and highly corrosive environments. Among the structural materials proposed both for in-core and out-of-core applications, elevated-temperature P91/P92 ferritic/martensitic steels have been considered. This work studies the transformation behavior and microstructural evolution of ASTM A335 P92 steel in continuous cooling cycles (CCT). The material was austenized at 1050 ºC and afterwards cooled down at controlled rates (300, 50 and 15 ºC/h). The determination and characterization of the phases present in the samples was performed by optical microscopy, field emission scanning electron microscopy, Mössbauer spectroscopy and X-ray diffraction. Samples whose cooling rates were on the limits of the studied range (300 and 15 ºC/h) presented completely martensitic and completely ferritic structures, respectively. The sample cooled down at intermediate rate exhibited, though, a mixed structure of martensite and ferrite. Second-phase precipitation has also been observed in all the samples. (author)

Cooling for SC devices of test cryomodule for ADS Injector II at IMP

Energy Technology Data Exchange (ETDEWEB)

Wang, L.; Wang, S. Y.; Sun, S.; Wang, S. H.; Liu, Y. Y. [Shanghai Institute of Applied Physics, CAS, Shanghai 201204 (China); Guo, X. L. [JiangSu University, Zhenjiang 212013 (China)

2014-01-29

The superconducting half-wave resonance cavities connected in series with superconducting solenoids will be applied to the Injector II of the Accelerator Driven Sub-critical System (ADS) to be built at the Modern Physics Institute, China. A test system has been developed for the purpose of performance test of the HWR cavities as well as validating the relevant technique for cooling the cavity and the solenoids together. It mainly comprises a cryogenic valve box (TVB), a test cryomodule (TCM1) and transfer lines. The TCM1 includes one HWR cavity, two superconducting solenoids, one cold BPM and their cooling system. The design of the TCM1 cryostat was carried out by the Shanghai Institute of Applied Physics (SINAP), CAS. Both the cavity and the solenoids will work at 4.4 K by bath cooling. The fast cooling down for the cavity from around 100 K to 120 K is required to avoid degrading of the cavity performance. After cool down and before energization, the solenoids should be warmed up to above 10 K and re-cooled down for the purpose of degaussing. The TCM1 can not only be cooled by using the dewar-filling system, but also operated by the refrigerator system. For the purpose of reducing the heat loads to the cold mass at 4 K from room temperature, thermal radiation shields cooled by liquid nitrogen flowing in tubing were employed. This paper presents the design details of cooling circuits and thermal shields of the TCM1 as well as related calculations and analyses.

Film cooling air pocket in a closed loop cooled airfoil

Science.gov (United States)

Yu, Yufeng Phillip; Itzel, Gary Michael; Osgood, Sarah Jane; Bagepalli, Radhakrishna; Webbon, Waylon Willard; Burdgick, Steven Sebastian

2002-01-01

Turbine stator vane segments have radially inner and outer walls with vanes extending between them. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. To provide for air film cooing of select portions of the airfoil outer surface, at least one air pocket is defined on a wall of at least one of the cavities. Each air pocket is substantially closed with respect to the cooling medium in the cavity and cooling air pumped to the air pocket flows through outlet apertures in the wall of the airfoil to cool the same.

Lighting and cooling energy consumption in an open-plan office using solar film coating

International Nuclear Information System (INIS)

Li, Danny H.W.; Lam, Tony N.T.; Wong, S.L.; Tsang, Ernest K.W.

2008-01-01

In subtropical Hong Kong, solar heat gain via glazing contributes to a significant proportion of the building envelope cooling load. The principal fenestration design includes eliminating direct sunlight and reducing cooling requirements. Daylighting is an effective approach to allow a flexible building facade design strategy, and to enhance an energy-efficient and green building development. This paper studies the lighting and cooling energy performances for a fully air-conditioned open-plan office when solar control films together with daylight-linked lighting controls are being used. Measurements were undertaken at two stages including the electricity expenditures for the office using photoelectric dimming controls only (first stage) and together with the solar control film coatings on the windows (second stage). Electric lighting and cooling energy consumption, transmitted daylight illuminance and solar radiation were systematically recorded and analysed. The measured data were also used for conducting and validating the building energy simulations. The findings showed that the solar film coatings coupled with lighting dimming controls cut down 21.2% electric lighting and 6.9% cooling energy consumption for the open-plan office

Experimental performance of evaporative cooling pad systems in greenhouses in humid subtropical climates

International Nuclear Information System (INIS)

Xu, J.; Li, Y.; Wang, R.Z.; Liu, W.; Zhou, P.

2015-01-01

Highlights: • Experimental performance of evaporative cooling in humid climate is investigated. • 5 working modes are studied in the greenhouse. • Vertical and horizontal temperature and relative humidity variations are analysed. • Indoor temperature can be kept in required level by proper working modes. - Abstract: To solve the overheating problem caused by the solar radiation and to keep the indoor temperature and humidity at a proper level for plants or crops, cooling technologies play vital role in greenhouse industry, and among which evaporative cooling is one of the most commonly-used methods. However, the main challenge of the evaporative cooling is its suitability to local climatic and agronomic condition. In this study, the performance of evaporative cooling pads was investigated experimentally in a 2304-m 2 glass multi-span greenhouse in Shanghai in the southeast of China. Temperature and humidity distributions were measured and reported for different working modes, including the use of evaporative cooling alone and the use of evaporative cooling with shading or ventilation. These experiments were conducted in humid subtropical climates where were considered unfavourable for evaporative cooling pad systems. Quantified analyses from the energy perspective are also made based on the experimental results and the evaporative cooling fan–pad system is demonstrated to be an effective option for greenhouse cooling even in the humid climate. Suggestions and possible solutions for further improving the performance of the system are proposed. The results of this work will be useful for the optimisation of the energy management of greenhouses in humid climates and for the validation of the mathematical model in future work

Variability of radiatively forced diurnal cycle of intense convection in the tropical west pacific

Energy Technology Data Exchange (ETDEWEB)

Gray, W.M.; Sheaffer, J.D.; Thorson, W.B. [Colorado State Univ., Fort Collins, CO (United States)

1996-04-01

Strong differences occur in daytime versus nighttime (DVN) net radiative cooling in clear versus cloudy areas of the tropical atmosphere. Daytime average cooling is approximately -0.7{degrees}C/day, whereas nighttime net tropospheric cooling rates are about -1.5{degrees}C/day, an approximately two-to-one difference. The comparatively strong nocturnal cooling in clear areas gives rise to a diurnally varying vertical circulation and horizontal convergence cycle. Various manifestations of this cyclic process include the observed early morning heavy rainfall maxima over the tropical oceans. The radiatively driven DVN circulation appears to strongly modulate the resulting diurnal cycle of intense convection which creates the highest, coldest cloudiness over maritime tropical areas and is likely a fundamental mechanism governing both small and large scale dynamics over much of the tropical environment.

CRC handbook of radiobiology

International Nuclear Information System (INIS)

Prasad, K.N.

1984-01-01

The author presents Development of Radiobiology. A Review. Basic Cell Biology. Physics of Radiation Biology. Cellular Radiation Damage. Modifications of Cellular Radiation Damage. Repair of Radiation Damage. Molecular Radiation Biology. Radiation Syndromes and their Modifications. Radiation Damage of Skin and Mucous Membrane. Radiation Damage of Nervous Tissue. Radiation Damage of Reproductive Organs. Radiation Damage of Other Organ Systems. Radiation Immunology. Background, Medical and Commercial Sources. Radiation Injuries to Human Fetuses. Radiation-Induced Genetic Damage. Radiation Carcinogenesis: Tissue Culture Model. Radiation Carcinogenesis: Animal Model. Radiation Carcinogenesis: Human Model. Radiation Carcinogenesis: Secondary Neoplasms. After Therapy of Tumors. Other Late Effects: Aging, Cataract, Aplastic Anemia. Maximum Permissible Dose (MPD). Radiation Response of Human Tumor. Radioisotopes in Biology and Medicine

Thermal histories of chondrules in solar nebula shocks, including the effect of molecular line cooling

Science.gov (United States)

Morris, Melissa A.

Chondrules are millimeter-sized, silicate (mostly ferromagnesian) igneous spheres found within chondritic meteorites. They are some of the oldest materials in our Solar System, having formed within a few million years of its birth. Chondrules were melted at high temperature (over 1800 K), while they were free-floating objects in the early solar nebula. Their petrology and chemistry constrain their formation, especially their thermal histories. Chondrules provide some of the most powerful constraints on conditions in the solar nebula. Models in which chondrule precursors melted by passage through solar nebula shocks are very promising, and meet most constraints on chondrule formation in broad brush. However, these models have been lacking in some of the relevant physics. Previous shock models have used incorrect approximations to the input radiation boundary condition, and the opacity of solids has been treated simply. Most important, a proper treatment of cooling due to molecular line emission has not been included. In this thesis, the shock model is significantly improved in order to determine if it remains consistent with observational constraints. The appropriate boundary condition for the input radiation and the proper method for calculation of the opacity of solids are determined, and a complete treatment of molecular line cooling due to water is included. Previous estimates of the effect of line cooling predicted chondrule cooling rates in excess of 10,000 K per hour. However, once molecular line cooling due to water was incorporated into the full shock model, it was found that line cooling has a minimal effect on the thermal histories of gas and chondrules. This behavior is attributed mostly to the thermal buffering of the gas due to hydrogen dissociation and recombination, which tends to keep the gas temperature at approximately 2000 K until the column densities of water become optically thick to line emission. Chondrule cooling rates in the range of 10

Influence of preliminary radiation-oxidizing treatment on the corrosion resistance of zirconium in conditions of action of ionizing radiation

International Nuclear Information System (INIS)

Garibov, A. A.; Aliyev, A. G.; Agayev, T. N.; Velibekova, G. Z.

2004-01-01

Today mainly water-cooled nuclear reactors predominate in atomic energetics. For safe work of nuclear reactors detection of accumulation process of explosives, formed during radiation and temperature influence on heat-carriers in contact with materials of nuclear reactors in normal and emergency regimes of work is of great importance. The main sources of molecular hydrogen formation in normal and emergency regimes are the processes of liquid and vaporous water in vapo metallic reaction [1-5]. At the result of these processes molecular hydrogen concentration in heat-carrier composition always exceeds theoretically expected concentration. One of the main ways to solve the problem of water-cooled reactors safety is detection of possibilities to raise material resistance of fuel elements and heat carrier to joint action of ionizing radiation and temperature. The second way is inhibition of radiation-catalytic activity of construction materials' surface during the process of water decomposition. It's been established, that one of the ways to raise resistance of zirconium materials to the influence of ionizing radiation is formation of thin oxide film on the surface of metals. In the given work the influence of preliminary oxidizing treatment of zirconium surface on its radiation-catalytic activity during the process of water decomposition. With this aim zirconium is exposed to preliminary influence of gamma-quantum in contact with hydrogen peroxide at different meanings of absorbed radiation dose

Modeling skin cooling using optical windows and cryogens during laser induced hyperthermia in a multilayer vascularized tissue

International Nuclear Information System (INIS)

Singh, Rupesh; Das, Koushik; Okajima, Junnosuke; Maruyama, Shigenao; Mishra, Subhash C.

2015-01-01

This article deals with the spatial and the temporal evolution of tissue temperature during skin surface cooled laser induced hyperthermia. Three different skin surface cooling methodologies viz., optical window contact cooling, cryogenic spray cooling and cryogen cooled optical window contact cooling are considered. Sapphire, yttrium aluminum garnet, lithium tantalate, and magnesium oxide doped lithium niobate are the considered optical windows. The cryogens considered are liquid CO_2 and R1234yf. Heat transfer in the multilayer skin tissue embedded with thermally significant blood vessels pairs is modeled using the Pennes and Weinbaum–Jiji bioheat equations. Weinbaum–Jiji bioheat equation is used for the vascularized tissue. Laser transport in the tissue is modeled using the radiative transfer equation. Axial and radial (skin surface) temperature distributions for different combinations of optical windows and cryogens are analyzed. Liquid CO_2 cooled yttrium aluminum garnet is found to be the best surface cooling mechanism. - Highlights: • Skin surface cooled laser induced hyperthermia is studied. • A multi-layer 2-D cylindrical tissue geometry is considered. • Both Pennes and Weinbaum–Jiji bioheat models are considered. • Laser transport in the tissue is modeled using discrete ordinate method. • Results for 4 optical windows and 2 cryogens for skin cooling are presented.

Man-portable personal cooling garment based on vacuum desiccant cooling

International Nuclear Information System (INIS)

Yang Yifan; Stapleton, Jill; Diagne, Barbara Thiané; Kenny, Glen P.; Lan, Christopher Q.

2012-01-01

A man-portable personal cooling garment based on the concept of vacuum desiccant cooling (VDC) was developed. It was demonstrated with cooling pads that a cooling capacity of 373.1 W/m 2 could be achieved in an ambient environment of 37 °C. Tests with human subjects wearing prototype cooling garments consisting of 12 VDC pads with an overall weight of 3.4 kg covering 0.4 m 2 body surface indicate that the garment could maintain a core temperature substantially lower than the control when the workload was walking on a treadmill of 2% inclination at 3 mph. The exercise was carried out in an environment of 40 °C and 50% relative humidity (RH) for 60 min. Tests also showed that the VDC garment could effectively reduce the metabolic heat accumulation in body with subject wearing heavily insulated nuclear, biological and chemical (NBC) suit working in the heat and allow the participant to work safely for 60 min, almost doubling the safe working time of the same participant when he wore NBC suit only. - Highlights: ► Heat stress mitigation is important for workers health, safety, and performance. ► Vacuum desiccant cooling (VDC) a novel concept for personal cooling. ► VDC garment man-portable and more efficient than commercial ice/pad vest. ► VDC garment suitable for personal cooling with NBC suit.

Laser cooling of solids

CERN Document Server

Petrushkin, S V

2009-01-01

Laser cooling is an important emerging technology in such areas as the cooling of semiconductors. The book examines and suggests solutions for a range of problems in the development of miniature solid-state laser refrigerators, self-cooling solid-state lasers and optical echo-processors. It begins by looking at the basic theory of laser cooling before considering such topics as self-cooling of active elements of solid-state lasers, laser cooling of solid-state information media of optical echo-processors, and problems of cooling solid-state quantum processors. Laser Cooling of Solids is an important contribution to the development of compact laser-powered cryogenic refrigerators, both for the academic community and those in the microelectronics and other industries. Provides a timely review of this promising field of research and discusses the fundamentals and theory of laser cooling Particular attention is given to the physics of cooling processes and the mathematical description of these processes Reviews p...

To cool, but not too cool: that is the question--immersion cooling for hyperthermia.

Science.gov (United States)

Taylor, Nigel A S; Caldwell, Joanne N; Van den Heuvel, Anne M J; Patterson, Mark J

2008-11-01

Patient cooling time can impact upon the prognosis of heat illness. Although ice-cold-water immersion will rapidly extract heat, access to ice or cold water may be limited in hot climates. Indeed, some have concerns regarding the sudden cold-water immersion of hyperthermic individuals, whereas others believe that cutaneous vasoconstriction may reduce convective heat transfer from the core. It was hypothesized that warmer immersion temperatures, which induce less powerful vasoconstriction, may still facilitate rapid cooling in hyperthermic individuals. Eight males participated in three trials and were heated to an esophageal temperature of 39.5 degrees C by exercising in the heat (36 degrees C, 50% relative humidity) while wearing a water-perfusion garment (40 degrees C). Subjects were cooled using each of the following methods: air (20-22 degrees C), cold-water immersion (14 degrees C), and temperate-water immersion (26 degrees C). The time to reach an esophageal temperature of 37.5 degrees C averaged 22.81 min (air), 2.16 min (cold), and 2.91 min (temperate). Whereas each of the between-trial comparisons was statistically significant (P < 0.05), cooling in temperate water took only marginally longer than that in cold water, and one cannot imagine that the 45-s cooling time difference would have any meaningful physiological or clinical implications. It is assumed that this rapid heat loss was due to a less powerful peripheral vasoconstrictor response, with central heat being more rapidly transported to the skin surface for dissipation. Although the core-to-water thermal gradient was much smaller with temperate-water cooling, greater skin and deeper tissue blood flows would support a superior convective heat delivery. Thus, a sustained physiological mechanism (blood flow) appears to have countered a less powerful thermal gradient, resulting in clinically insignificant differences in heat extraction between the cold and temperate cooling trials.

The assessment of ionising radiation impact on the cooling pond freshwater ecosystem non-human biota from the Ignalina NPP operation beginning to shut down and initial decommissioning.

Science.gov (United States)

Mazeika, J; Marciulioniene, D; Nedveckaite, T; Jefanova, O

2016-01-01

The radiological doses to non-human biota of freshwater ecosystem in the Ignalina NPP cooling pond - Lake Druksiai were evaluated for several cases including the plant's operation period and initial decommissioning activities, using the ERICA 1.2 code with IAEA SRS-19 models integrated approach and tool. Among the Lake Druksiai freshwater ecosystem reference organisms investigated the highest exposure dose rate was determined for bottom fauna - benthic organisms (mollusc-bivalves, crustaceans, mollusc-gastropods, insect larvae), and among the other reference organisms - for vascular plants. The mean and maximum total dose rate values due to anthropogenic radionuclide ionising radiation impact in all investigated cases were lower than the ERICA screening dose rate value of 10 μGy/h. The main exposure of reference organisms as a result of Ignalina NPP former effluent to Lake Druksiai is due to ionizing radiation of radionuclides (60)Co and (137)Cs, of predicted releases to Lake Druksiai during initial decommissioning period - due to radionuclides (60)Co, (134)Cs and (137)Cs, and as a result of predicted releases to Lake Druksiai from low- and intermediate-level short-lived radioactive waste disposal site in 30-100 year period - due to radionuclides (99)Tc and (3)H. The risk quotient expected values in all investigated cases were <1, and therefore the risk to non-human biota can be considered negligible with the exception of a conservative risk quotient for insect larvae. Radiological protection of non-human biota in Lake Druksiai, the Ignalina NPP cooling pond, is both feasible and acceptable. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spectral response data for development of cool coloured tile coverings

Science.gov (United States)

Libbra, Antonio; Tarozzi, Luca; Muscio, Alberto; Corticelli, Mauro A.

2011-03-01

Most ancient or traditional buildings in Italy show steep-slope roofs covered by red clay tiles. As the rooms immediately below the roof are often inhabited in historical or densely urbanized centres, the combination of low solar reflectance of tile coverings and low thermal inertia of either wooden roof structures or sub-tile insulation panels makes summer overheating a major problem. The problem can be mitigated by using tiles coated with cool colours, that is colours with the same spectral response of clay tiles in the visible, but highly reflecting in the near infrared range, which includes more than half of solar radiation. Cool colours can yield the same visible aspect of common building surfaces, but higher solar reflectance. Studies aimed at developing cool colour tile coverings for traditional Italian buildings have been started. A few coating solutions with the typical red terracotta colour have been produced and tested in the laboratory, using easily available materials. The spectral response and the solar reflectance have been measured and compared with that of standard tiles.

Performance characteristic of hybrid cooling system based on cooling pad and evaporator

Science.gov (United States)

Yoon, J. I.; Son, C. H.; Choi, K. H.; Kim, Y. B.; Sung, Y. H.; Roh, S. J.; Kim, Y. M.; Seol, S. H.

2018-01-01

In South Korea, most of domestic animals such as pigs and chickens might die due to thermal diseases if they are exposed to the high temperature consistently. In order to save them from the heat wave, numerous efforts have been carried out: installing a shade net, adjusting time of feeding, spraying mist and setting up a circulation fan. However, these methods have not shown significant improvements. Thus, this study proposes a hybrid cooling system combining evaporative cooler and air-conditioner in order to resolve the conventional problems caused by the high temperature in the livestock industry. The problem of cooling systems using evaporative cooling pads is that they are not effective for eliminating huge heat load due to their limited capacity. And, temperature of the supplied air cannot be low enough compared to conventional air-conditioning systems. On the other hand, conventional air-conditioning systems require relatively expensive installation cost, and high operating cost compared to evaporative cooling system. The hybrid cooling system makes up for the lack of cooling capacity of the evaporative cooler by employing the conventional air-conditioner. Additionally, temperature of supplied air can be lowered enough. In the hybrid cooling system, induced air by a fan is cooled by the evaporation of water in the cooling pad, and it is cooled again by an evaporator in the air-conditioner. Therefore, the more economical operation is possible due to additionally obtained cooling capacity from the cooling pads. Major results of experimental analysis of hybrid cooling system are as follows. The compressor power consumption of the hybrid cooling system is about 23% lower, and its COP is 17% higher than that of the conventional air-conditioners. Regarding the condition of changing ambient temperature, the total power consumption decreased by about 5% as the ambient temperature changed from 28.7°C to 31.7°C. Cooling capacity and COP also presented about 3% and 1

Spray cooling

International Nuclear Information System (INIS)

Rollin, Philippe.

1975-01-01

Spray cooling - using water spraying in air - is surveyed as a possible system for make-up (peak clipping in open circuit) or major cooling (in closed circuit) of the cooling water of the condensers in thermal power plants. Indications are given on the experiments made in France and the systems recently developed in USA, questions relating to performance, cost and environmental effects of spray devices are then dealt with [fr

Investigation of the radiation leakage from X ray flaw detectors and the improvement measures for the unqualified products

International Nuclear Information System (INIS)

Li Yiachun; Wu Yi; Pang Hu; Bai Bin

1997-01-01

The authors introduce investigation methods and results for radiation leakage from X ray flaw detectors, which are used in Beijing area. Total 21 sets of flaw detectors made in 8 factories in Beijing, Shanghai etc. have been tested, of which 16 sets made in Beijing, Dandong and Japan are gas cooling flaw detectors, and rest 5 sets made in Shanghai and Germany are water or oil cooling detectors. The air Kerma rate of leakage radiation at 1 m from the X ray tube target were measured by Type FJ-347A X, γ dosimeter. It can be seen from the results that, compared with the trade standard ZBY315-83, 5 sets of water or oil cooling flaw detectors are all qualified. However, only two sets of gas cooling detectors are qualified, and the radiation leakage of another 14 sets are over the values specified in the standard. The reason is analyzed, and some advices about the measures of improving radiation protection structure design and production technology for the unqualified products have been proposed

Heat transfer problems in gas-cooled solid blankets

International Nuclear Information System (INIS)

Fillo, J.A.; Powell, J.R.

1976-01-01

In all fusion reactors using the deuterium-tritium fuel cycle, a large fraction approximately 80 percent of the fusion energy will be released as approximately 14 MeV neutrons which must be slowed down in a relatively thick blanket surrounding the plasma, thereby, converting their kinetic energy to high temperature heat which can be continuously removed by a coolant stream and converted in part to electricity in a conventional power turbine. Because of the primary goal of achieving minimum radioactivity, to date Brookhaven blanket concepts have been restricted to the use of some form of solid lithium, with inert gas-cooling and in some design cases, water-cooling of the shell structure. Aluminum and graphite have been identified as very promising structural materials for fusion blankets, and conceptual designs based on these materials have been made. Depending on the thermal loading on the ''first'' wall which surrounds the plasma as well as blanket design, heat transfer problems may be noticeably different in gas-cooled solid blankets. Approaches to solution of heat removal problems as well as explanation of: (a) the after-heat problems in blankets; (b) tritium breeding in solids; and (c) materials selection for radiation shields relative to the minimum activity blanket efforts at Brookhaven are discussed

Application of ionizing radiation in treatment of meat

International Nuclear Information System (INIS)

Sedlackova, J.

1984-01-01

Processes used for meat treatment for storage (cooling, radurization + cooling, freezing, heat treatment and radappertization) are compared with regard to energy demand. The effect of doses above 10 kGy and below 10 kGy are discussed. Doses of ionizing radiation may be combined with other techniques (heat treatment, the addition of certain chemicals or antibiotics). Czechoslovak experience with irradiation of meat with tapeworm cysticerci is described. (E.F.)

Radiation shielding material

International Nuclear Information System (INIS)

Kawakubo, Takamasa; Yamada, Fumiyuki; Nakazato, Kenjiro.

1976-01-01

Purpose: To provide a material, which is used for printing a samples name and date on an X-ray photographic film at the same time an X-ray radiography. Constitution: A radiation shielding material of a large mass absorption coefficient such as lead oxide, barium oxide, barium sulfate, etc. is added to a solution of a radiation permeable substance capable of imparting cold plastic fluidity (such as microcrystalline wax, paraffin, low molecular polyethylene, polyvinyl chloride, etc.). The resultant system is agitated and then cooled, and thereafter it is press fitted to or bonded to a base in the form of a film of a predetermined thickness. This radiation shielding layer is scraped off by using a writing tool to enter information to be printed in a photographic film, and then it is laid over the film and exposed to X-radiation to thereby print the information on the film. (Seki, T.)

Initial three-dimensional neutronics calculations for the EU water cooled lithium-lead test blanket module for ITER-FEAT

International Nuclear Information System (INIS)

Jordanova, J.; Poitevin, Y.; Li Puma, A.; Kirov, N.

2003-01-01

The paper summarizes the main results of the initial three-dimensional radiation transport analysis of the EU water-cooled lithium-lead test blanket module performed using the Monte Carlo code MCNP. Estimates of tritium production rate, nuclear energy deposition and cumulative fluence effects such as radiation damage through atomic displacement and production of He and H are presented. (author)

Compound Semiconductor Radiation Detectors

CERN Document Server

Owens, Alan

2012-01-01

Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

Design of sodium cooled reactor systems and components for maintainability

International Nuclear Information System (INIS)

Carr, R.W.; Charnock, H.O.; McBride, J.P.

1978-09-01

Special maintenability problems associated with the design and operation of sodium cooled reactor plants are discussed. Some examples of both good and bad design practice are introduced from the design of the FFTF plant and other plants. Subjects include design for drainage, cleaning, decontamination, access, component removal, component disassembly and reassembly, remote tooling, jigs, fixtures, and design for minimizing radiation exposure of maintenance personnel. Check lists are included

Spacesuit Water Membrane Evaporator; An Enhanced Evaporative Cooling Systems for the Advanced Extravehicular Mobility Unit Portable Life Support System

Science.gov (United States)

Bue, Grant C.; Makinen, Janice V.; Miller, Sean.; Campbell, Colin; Lynch, Bill; Vogel, Matt; Craft, Jesse; Petty, Brian

2014-01-01

Spacesuit Water Membrane Evaporator - Baseline heat rejection technology for the Portable Life Support System of the Advanced EMU center dot Replaces sublimator in the current EMU center dot Contamination insensitive center dot Can work with Lithium Chloride Absorber Radiator in Spacesuit Evaporator Absorber Radiator (SEAR) to reject heat and reuse evaporated water The Spacesuit Water Membrane Evaporator (SWME) is being developed to replace the sublimator for future generation spacesuits. Water in LCVG absorbs body heat while circulating center dot Warm water pumped through SWME center dot SWME evaporates water vapor, while maintaining liquid water - Cools water center dot Cooled water is then recirculated through LCVG. center dot LCVG water lost due to evaporation (cooling) is replaced from feedwater The Independent TCV Manifold reduces design complexity and manufacturing difficulty of the SWME End Cap. center dot The offset motor for the new BPV reduces the volume profile of the SWME by laying the motor flat on the End Cap alongside the TCV.

R&D for the local support structure and cooling channel for the ATLAS PIXEL Detector Insertable B-Layer (IBL)

CERN Document Server

Coelli, S; The ATLAS collaboration

2010-01-01

ABSTRACT: The scope of the present R&D is to develop an innovative support, with an integrated cooling and based on carbon composites, for the electronic sensors of the Silicon Pixel Tracker, to be installed into the ATLAS Experiment on the Large Hadron Collider at CERN. The inner layer of the detector is installed immediately outside the Beryllium beam pipe at a distance of 50 mm from the Interaction Point, where the high energy protons collide: the intense radiation field induce a radiation damage on the sensors so that a cooling system is necessary to remove the electrical power dissipated as heat, maintaining the sensor temperature sufficiently low. The task of the support system is to hold the detector modules in positions with high accuracy, minimizing the deformation induced by the cooling; this must be done with the lower possible mass because there are tight requirements in terms of material budget. An evaporative boiling system to remove the power dissipated by the sensors is incorporated in the...

Thermal and structural analysis of a cryogenic conduction cooling system for a HTS NMR magnet

Energy Technology Data Exchange (ETDEWEB)

In, Se Hwan; Hong, Yong Jun; Yeom, Han Kil; Ko, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

2016-03-15

The superconducting NMR magnets have used cryogen such as liquid helium for their cooling. The conduction cooling method using cryocoolers, however, makes the cryogenic cooling system for NMR magnets more compact and user-friendly than the cryogen cooling method. This paper describes the thermal and structural analysis of a cryogenic conduction cooling system for a 400 MHz HTS NMR magnet, focusing on the magnet assembly. The highly thermo-conductive cooling plates between HTS double pancake coils are used to transfer the heat generated in coils, namely Joule heating at lap splice joints, to thermal link blocks and finally the cryocooler. The conduction cooling structure of the HTS magnet assembly preliminarily designed is verified by thermal and structural analysis. The orthotropic thermal properties of the HTS coil, thermal contact resistance and radiation heat load are considered in the thermal analysis. The thermal analysis confirms the uniform temperature distribution for the present thermal design of the NMR magnet within 0.2 K. The mechanical stress and the displacement by the electromagnetic force and the thermal contraction are checked to verify structural stability. The structural analysis indicates that the mechanical stress on each component of the magnet is less than its material yield strength and the displacement is acceptable in comparison with the magnet dimension.

Emergency reactor cooling device

International Nuclear Information System (INIS)

Arakawa, Ken.

1993-01-01

An emergency nuclear reactor cooling device comprises a water reservoir, emergency core cooling water pipelines having one end connected to a water feeding sparger, fire extinguishing facility pipelines, cooling water pressurizing pumps, a diesel driving machine for driving the pumps and a battery. In a water reservoir, cooling water is stored by an amount required for cooling the reactor upon emergency and for fire extinguishing, and fire extinguishing facility pipelines connecting the water reservoir and the fire extinguishing facility are in communication with the emergency core cooling water pipelines connected to the water feeding sparger by system connection pipelines. Pumps are operated by a diesel power generator to introduce cooling water from the reservoir to the emergency core cooling water pipelines. Then, even in a case where AC electric power source is entirely lost and the emergency core cooling system can not be used, the diesel driving machine is operated using an exclusive battery, thereby enabling to inject cooling water from the water reservoir to a reactor pressure vessel and a reactor container by the diesel drive pump. (N.H.)

Universal crystal cooling device for precession cameras, rotation cameras and diffractometers

International Nuclear Information System (INIS)

Hajdu, J.; McLaughlin, P.J.; Helliwell, J.R.; Sheldon, J.; Thompson, A.W.

1985-01-01

A versatile crystal cooling device is described for macromolecular crystallographic applications in the 290 to 80 K temperature range. It utilizes a fluctuation-free cold-nitrogen-gas supply, an insulated Mylar crystal cooling chamber and a universal ball joint, which connects the cooling chamber to the goniometer head and the crystal. The ball joint is a novel feature over all previous designs. As a result, the device can be used on various rotation cameras, precession cameras and diffractometers. The lubrication of the interconnecting parts with graphite allows the cooling chamber to remain stationary while the crystal and goniometer rotate. The construction allows for 360 0 rotation of the crystal around the goniometer axis and permits any settings on the arcs and slides of the goniometer head (even if working at 80 K). There are no blind regions associated with the frame holding the chamber. Alternatively, the interconnecting ball joint can be tightened and fixed. This results in a set up similar to the construction described by Bartunik and Schubert where the cooling chamber rotates with the crystal. The flexibility of the systems allows for the use of the device on most cameras or diffractometers. THis device has been installed at the protein crystallographic stations of the Synchrotron Radiation Source at Daresbury Laboratory and in the Laboratory of Molecular Biophysics, Oxford. Several data sets have been collected with processing statistics typical of data collected without a cooling chamber. Tests using the full white beam of the synchrotron also look promising. (orig./BHO)

Aqueous self-cooled blanket concepts for fusion reactors

International Nuclear Information System (INIS)

Varsamis, G.; Embrechts, M.J.; Steiner, D.; Deutsch, L.; Gierszewski, P.

1987-01-01

A novel aqueous self-cooled blanket (ASCB) concept has been proposed. The water coolant also serves as the tritium breeding medium by dissolving small amounts of lithium compound in the water. The tritium recovery requirements of the ASCB concept may be facilitated by the novel in-situ radiolytic tritium separation technique in development at Chalk River Nuclear Laboratories. In this separation process deuterium gas is bubbled through the blanket coolant. Due to radiation induced processes, the equilibrium constant favors tritium migration to the deuterium gas stream. It is expected that the inherent simplicity of this design will result in a highly reliable, safe and economically attractive breeding blanket for fusion reactors. The available base of relevant information accumulated through water-cooled fission reactor programs should greatly facilitate the R and D effort required to validate the proposed blanket concept. Tests for tritium separation and corrosion compatibility show encouraging results for the feasibility of this concept

Theoretical and experimental studies on the daily accumulative heat gain from cool roofs

International Nuclear Information System (INIS)

Qin, Yinghong; Zhang, Mingyi; Hiller, Jacob E.

2017-01-01

Cool roofs are gaining popularity as passive building cooling techniques, but the correlation between energy savings and rooftop albedo has not been understood completely. Here we theoretically model the daily accumulative inward heat (DAIH) from building roofs with different albedo values, correlating the heat gain of the building roof to both the rooftop albedo and the incident solar radiation. According to this model, the DAIH increases linearly with the daily zenith solar radiation, but decreases linearly with the rooftop albedo. A small building cell was constructed to monitor the heat gain of the building under the conditions of non-insulated and insulated roofs. The observational DAIH is highly coincident with the theoretical one, validating the theoretical model. It was found that insulating the roof, increasing the rooftop albedo, or both options can effectively curtail the heat gain in buildings during the summer season. The proposed theoretical model would be a powerful tool for evaluating the heat gain of the buildings and estimating the energy savings potential of high-reflective cool roofs. - Highlights: • Daily accumulative heat gain from a building roof is theoretically modeled. • Daily accumulative heat gain from a building roof increases linearly with rooftop absorptivity. • Increasing the roof insulation tapers the effect of the rooftop absorptivity. • The theoretical model is powerful for estimating energy savings of reflective roofs.

Radiation Effects in Dual Heat Sinks for Cooling of Concentrated Photovoltaics

Science.gov (United States)

2016-06-01

heat transfer out of a module is by radiation [7]. 1. Previous work Previous work in field has been focused on improving convection transfer via...LEFT BLANK 35 VII. CONCLUSION AND RECOMMENDATION A. CONCLUSION This thesis examined means to improve heat transfer out of a CPV module by... heat transfer by radiation to lower the operating temperature of the CPV system, and therefore increase the power output. Experimental and

Detection of gravitational radiation

Energy Technology Data Exchange (ETDEWEB)

Holten, J.W. van [ed.

1994-12-31

In this report the main contributions presented at the named symposium are collected. These concern astrophysical sources of gravitational radiation, ultracryogenic gravitational wave experiments, read out and data analysis of gravitational wave antennas, cryogenic aspects of large mass cooling to mK temperatures, and metallurgical and engineering aspects of large Cu structure manufacturing. (HSI).

Detection of gravitational radiation

International Nuclear Information System (INIS)

Holten, J.W. van

1994-01-01

In this report the main contributions presented at the named symposium are collected. These concern astrophysical sources of gravitational radiation, ultracryogenic gravitational wave experiments, read out and data analysis of gravitational wave antennas, cryogenic aspects of large mass cooling to mK temperatures, and metallurgical and engineering aspects of large Cu structure manufacturing. (HSI)

Gamma radiation detectors for safeguards applications

International Nuclear Information System (INIS)

Carchon, R.; Moeslinger, M.; Bourva, L.; Bass, C.; Zendel, M.

2007-01-01

The IAEA uses extensively a variety of gamma radiation detectors to verify nuclear material. These detectors are part of standardized spectrometry systems: germanium detectors for High-Resolution Gamma Spectrometry (HRGS); Cadmium Zinc Telluride (CZT) detectors for Room Temperature Gamma Spectrometry (RTGS); and NaI(Tl) detectors for Low Resolution Gamma Spectrometry (LRGS). HRGS with high-purity Germanium (HpGe) detectors cooled by liquid nitrogen is widely used in nuclear safeguards to verify the isotopic composition of plutonium or uranium in non-irradiated material. Alternative cooling systems have been evaluated and electrically cooled HpGe detectors show a potential added value, especially for unattended measurements. The spectrometric performance of CZT detectors, their robustness and simplicity are key to the successful verification of irradiated materials. Further development, such as limiting the charge trapping effects in CZT to provide improved sensitivity and energy resolution are discussed. NaI(Tl) detectors have many applications-specifically in hand-held radioisotope identification devices (RID) which are used to detect the presence of radioactive material where a lower resolution is sufficient, as they benefit from a generally higher sensitivity. The Agency is also continuously involved in the review and evaluation of new and emerging technologies in the field of radiation detection such as: Peltier-cooled CdTe detectors; semiconductor detectors operating at room temperature such as HgI 2 and GaAs; and, scintillator detectors using glass fibres or LaBr 3 . A final conclusion, proposing recommendations for future action, is made

Cooled-Spool Piston Compressor

Science.gov (United States)

Morris, Brian G.

1994-01-01

Proposed cooled-spool piston compressor driven by hydraulic power and features internal cooling of piston by flowing hydraulic fluid to limit temperature of compressed gas. Provides sufficient cooling for higher compression ratios or reactive gases. Unlike conventional piston compressors, all parts of compressed gas lie at all times within relatively short distance of cooled surface so that gas cooled more effectively.

Cooling towers

International Nuclear Information System (INIS)

Korik, L.; Burger, R.

1992-01-01

What is the effect of 0.6C (1F) temperature rise across turbines, compressors, or evaporators? Enthalpy charts indicate for every 0.6C (1F) hotter water off the cooling tower will require an additional 2 1/2% more energy cost. Therefore, running 2.2C (4F) warmer due to substandard cooling towers could result in a 10% penalty for overcoming high heads and temperatures. If it costs $1,250,000.00 a year to operate the system, $125,000.00 is the energy penalty for hotter water. This paper investigates extra fuel costs involved in maintaining design electric production with cooling water 0.6C (1F) to 3C (5.5F) hotter than design. If design KWH cannot be maintained, paper will calculate dollar loss of saleable electricity. The presentation will conclude with examining the main causes of deficient cold water production. State-of-the-art upgrading and methodology available to retrofit existing cooling towers to optimize lower cooling water temperatures will be discussed

Water cooling coil

Energy Technology Data Exchange (ETDEWEB)

Suzuki, S; Ito, Y; Kazawa, Y

1975-02-05

Object: To provide a water cooling coil in a toroidal nuclear fusion device, in which coil is formed into a small-size in section so as not to increase dimensions, weight or the like of machineries including the coil. Structure: A conductor arranged as an outermost layer of a multiple-wind water cooling coil comprises a hollow conductor, which is directly cooled by fluid, and as a consequence, a solid conductor disposed interiorly thereof is cooled indirectly.

Effect of closed loop cooling water transit time on containment cooling

International Nuclear Information System (INIS)

Smith, R.P.; Vossahlik, J.E.; Goodwin, E.F.

1996-01-01

Long term containment cooling analyses in nuclear plant systems are usually conducted assuming a quasi steady-state process, that is, a steady state evaluation of the cooling system is completed for each calculational step. In reality, fluid transport in the system, and heat addition to system components may affect the heat removal rate of the system. Transient effects occurring during system startup may affect the maximum temperatures experienced in the system. It is important to ensure that such transient effects do not affect operation of the system (e.g., cause a high temperature trip). To evaluate the effect of fluid transit delays, a closed loop cooling water system model has been developed that incorporates the fluid transport times when determining the closed loop cooling system performance. This paper describes the closed loop cooling system model as implemented in the CONTEMPT-LT/028 code. The evaluation of the transient temperature response of the closed loop cooling system using the model is described. The paper also describes the effect of fluid transit time on the overall containment cooling performance

Characteristics of fabricated si PIN-type radiation detectors on cooling temperature

Energy Technology Data Exchange (ETDEWEB)

Kim, Han Soo; Jeong, Manhee; Kim, Young Soo [Korea Atomic Energy Research Institute, Jeongeup-si 580-185 (Korea, Republic of); Lee, Dong Hun [Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of); Cho, Seung Yeon [Environmental Health Center, Yonsei University, Wonju-si 1184-4 (Korea, Republic of); Ha, Jang Ho [Korea Atomic Energy Research Institute, Jeongeup-si 580-185 (Korea, Republic of)

2015-06-01

Si PIN photodiode radiation detectors with three different active areas (3×3 mm{sup 2}, 5×5 mm{sup 2}, and 10×10 mm{sup 2}) were designed and fabricated at the Korea Atomic Energy Research Institute (KAERI) for low energy X- and gamma-ray detection. In Si-based semiconductor radiation detectors, one of the noise sources is thermal noise, which degrades their energy resolution performance. In this study, the temperature effects on the energy resolution were investigated using a 3×3 mm{sup 2} active area PIN photodiode radiation detector using a Thermoelectric Module (TEM) from room temperature to −23 °C. Energy resolutions from 25 keV auger electrons to 81 keV gamma-ray from a Ba-133 calibration source were measured and compared at every 10 °C interval. At −23 °C, energy resolutions were improved by 15.6% at 25 keV, 4.0% at 31 keV, and 1.2% at 81 keV in comparison with resolutions at room temperature. CsI(Tl)/PIN photodiode radiation detectors were also fabricated for relatively high energy gamma-ray detection. Energy resolutions for Cs-137, Co-60, and Na-22 sources were measured and compared with the spectral responsivity.

Theoretical analysis of the performance of different cooling strategies with the concept of cool exergy

DEFF Research Database (Denmark)

Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

2016-01-01

The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air for the v......The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air...... for the ventilation system being outdoor air vs. air from the crawl-space, and air-to-water heat pump vs. ground heat exchanger as cooling source) on system exergy performance were investigated. It is crucial to minimize the cooling demand because it is possible to use a wide range of heat sinks (ground, lake, sea......-water, etc.) and indoor terminal units, only with a minimized demand. The water-based floor cooling system performed better than the air-based cooling system; when an air-to-water heat pump was used as the cooling source, the required exergy input was 28% smaller for the floor cooling system. The auxiliary...

Residential building envelope heat gain and cooling energy requirements

International Nuclear Information System (INIS)

Lam, Joseph C.; Tsang, C.L.; Li, Danny H.W.; Cheung, S.O.

2005-01-01

We present the energy use situation in Hong Kong from 1979 to 2001. The primary energy requirement (PER) nearly tripled during the 23-year period, rising from 195,405 TJ to 572,684 TJ. Most of the PER was used for electricity generation, and the electricity use in residential buildings rose from 7556 TJ (2099 GWh) to 32,799 TJ (9111 GWh), an increase of 334%. Air-conditioning accounted for about 40% of the total residential sector electricity consumption. A total of 144 buildings completed in the month of June during 1992-2001 were surveyed. Energy performance of the building envelopes was investigated in terms of the overall thermal transfer value (OTTV). To develop the appropriated parameters used in OTTV calculation, long-term measured weather data such as ambient temperature (1960-2001), horizontal global solar radiation (1992-2001) and global solar radiation on vertical surfaces (1996-2001) were examined. The OTTV found varied from 27 to 44 W/m 2 with a mean value of 37.7 W/m 2 . Building energy simulation technique using DOE-2.1E was employed to determine the cooling requirements and hence electricity use for building envelope designs with different OTTVs. It was found that cooling loads and electricity use could be expressed in terms of a simple two-parameter linear regression equation involving OTTV

Heat rejection efficiency research of new energy automobile radiators

Science.gov (United States)

Ma, W. S.; Shen, W. X.; Zhang, L. W.

2018-03-01

The driving system of new energy vehicle has larger heat load than conventional engine. How to ensure the heat dissipation performance of the cooling system is the focus of the design of new energy vehicle thermal management system. In this paper, the heat dissipation efficiency of the radiator of the hybrid electric vehicle is taken as the research object, the heat dissipation efficiency of the radiator of the new energy vehicle is studied through the multi-working-condition enthalpy difference test. In this paper, the test method in the current standard QC/T 468-2010 “automobile radiator” is taken, but not limited to the test conditions specified in the standard, 5 types of automobile radiator are chosen, each of them is tested 20 times in simulated condition of different wind speed and engine inlet temperature. Finally, regression analysis is carried out for the test results, and regression equation describing the relationship of radiator heat dissipation heat dissipation efficiency air side flow rate cooling medium velocity and inlet air temperature is obtained, and the influence rule is systematically discussed.