Search results for "cooling"
showing 10 items of 470 documents
RELAP5-3D thermal hydraulic analysis of the target cooling system in the SPES experimental facility
2014
The SPES (Selective Production of Exotic Species) experimental facility, under construction at the Italian National Institute of Nuclear Physics (INFN) Laboratories of Legnaro, Italy, is a second generation Isotope Separation On Line (ISOL) plant for advanced nuclear physic studies. The UCx target-ion source system works at temperature of about 2273 K, producing a high level of radiation (10^5 Sv/h), for this reason a careful risk analysis for the target chamber is among the major safety issues. In this paper, the obtained results of thermofluid-dynamics simulations of accidental transients in the SPES target cooling system are reported. The analysis, performed by using the RELAP5-3D 2.4.2 …
Normal metal - insulator - superconductor thermometers and coolers with titanium-gold bilayer as the normal metal
2018
We have fabricated superconductor - insulator - normal metal - insulator - superconductor (SINIS) tunnel junctions in which Al acts as the superconductor, AlOx is the insulator, and the normal metal consists of a thin Ti layer (5 nm) covered with a thicker Au layer (40 nm). We have characterized the junctions by measuring their current-voltage curves between 60 mK and 750 mK. For comparison, the same measurements have been performed for a SINIS junction pair whose normal metal is Cu. The Ti-Au bilayer decreases the SINIS tunneling resistance by an order of magnitude compared to junctions where Cu is used as normal metal, made with the same oxidation parameters. The Ti-Au devices are much mo…
Partial Laser Cooling and Saturation Spectroscopy on 9 MeV 7Li+ - Ions in a Storage Ring
1989
Publisher Summary Laser cooling and spectroscopy in traps have reached impressive perfections. This chapter discusses laser cooling and partially Doppler-suppressed spectroscopy on stored ions at 5.4% speed of light in the test storage ring (TSR) heavy ion storage ring in Heidelberg. It discusses the requirements for saturation spectroscpy with two counterpropagating collinear laser beams. In contrast to Penning and RF-traps, the ions in a storage ring move at a high longitudinal velocity with small transverse harmonic oscillations around the central orbit with just a few times the orbiting frequency in the case of strong focussing. However, the injection of the high velocity beam introduce…
LIFE CYCLE BALANCES OF SOLAR COOLING SYSTEMS
2009
LIFE CYCLE BALANCES OF SOLAR COOLING SYSTEMS
Polar nanoregions in Pb(Mg1/3Nb2/3)O3 (PMN): insights from a supercell approach
2011
Abstract We report construction of a model of polar nanoregions in the PMN relaxor ferroelectric based on first-principles lattice dynamics for chemically ordered supercells [S.A. Prosandeev et al., Phys. Rev. B 70, 134110 (2004)], combined with invariance under permutations and dipole-dipole interaction as a source supporting randomly oriented residual polarization. Representative analytical estimates of polar nanore-gion — supercell mapping reproduce both nonzero local and zero macroscopic polarization of the structure, as well as the temperature change of the supercell anisotropy at cooling and field cooling.
The Ultimate Fate of Supercooled Liquids
2010
In recent years it has become widely accepted that a dynamical length scale {\xi}_{\alpha} plays an important role in supercooled liquids near the glass transition. We examine the implications of the interplay between the growing {\xi}_{\alpha} and the size of the crystal nucleus, {\xi}_M, which shrinks on cooling. We argue that at low temperatures where {\xi}_{\alpha} > {\xi}_M a new crystallization mechanism emerges enabling rapid development of a large scale web of sparsely connected crystallinity. Though we predict this web percolates the system at too low a temperature to be easily seen in the laboratory, there are noticeable residual effects near the glass transition that can account …
Nanoscale heterogeneity if glass-forming liquids: experimental advances
1998
Abstract Recent evidence indicates that in supercooled liquids the cooperativity of molecular motion extends over certain temporal and spatial ranges. A key advance is the experimental and theoretical exploration of higher-order correlation functions that can track the molecular coordinates for more than just two points in time or space. Uncontested experimental determinations of the heterogeneity length scale at the glass transition remain a major goal.
Growing length scales in a supercooled liquid close to an interface
2002
We present the results of molecular dynamics computer simulations of a simple glass former close to an interface between the liquid and the frozen amorphous phase of the same material. By investigating F_s(q,z,t), the incoherent intermediate scattering function for particles that have a distance z from the wall, we show that the relaxation dynamics of the particles close to the wall is much slower than the one for particles far away from the wall. For small z the typical relaxation time for F_s(q,z,t) increases like exp(Delta/(z-z_p)), where Delta and z_p are constants. We use the location of the crossover from this law to the bulk behavior to define a first length scale tilde{z}. A differe…
Task 38 Solar Air-Conditioning and Refrigeration “Life Cycle Assessment of Solar Cooling Systems” A technical report of subtask D Subtask Activity D3
2010
Renewable energy (RE) systems can certainly allow reducing the use of fossil fuels and the related environmental impacts for building air-conditioning. It is more and more clear that good design of the system and appropriateness of the technology are a key issues on the way to maximise the benefits. Therefore, for systems dealing with solar thermal systems, it has been experienced that wrong choices among RE technologies to meet specific applications could also lead to negative effects in terms of Primary Energy (PE) saving.
Energy and environmental life-cycle impacts of solar-assisted systems: The application of the tool “ELISA”
2020
Abstract Solar heating and cooling (SHC) systems can be relevant in the achievement of energy and climate European goals. The benefits of these technologies should be evaluated taking into account their life-cycle energy and environmental impacts, calculated by applying the Life Cycle Assessment (LCA). The development of a complete LCA can be difficult and time-consuming particularly for non-experts in LCA, discouraging them in developing the life-cycle assessments. To overcome this issue, the paper presents “ELISA - Environmental Lifecycle Impacts of Solar Air-conditioning systems”, a user-friendly simplified tool for estimating the life-cycle energy and environmental benefits/impacts of s…