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Energy transfer media

As described above, quantum restrictions limit tire contribution of tire free electrons in metals to the heat capacity to a vety small effect. These same electrons dominate the thermal conduction of metals acting as efficient energy transfer media in metallic materials. The contribution of free electrons to thermal transport is very closely related to their role in the transport of electric current tlrrough a metal, and this major effect is described through the Wiedemann-Franz ratio which, in the Lorenz modification, states that... [Pg.167]

Remarkably, however, textbooks on mass spectrometry hardly comprise the multifaceted aspects of the gas-phase ion chemistry of phenols and of their consequences for the characteristics of the mass spectra of phenolic compounds . A great many insights into the fundamentals and developments for analytical applications have been collected during the past four decades or so, and research is actively continued in this field. As a special circumstance, a number of phenolic compounds play a crucial—and yet not completely understood—role as energy-transferring media and protonating reagents in an extremely important, modern ionization method of mass spectrometry, viz. matrix-assisted laser desorption/ionization (MALDI) . ... [Pg.260]

More recently Peng and Song reported the rapid synthesis of a library of hydrazides in a MW-US combined reactor (Scheme 9.20)139. Unlike the aforementioned system that employed decalin as an energy transfer medium for the ultrasound irradiation, in their modified domestic oven, the horn was immersed directly into the reaction mixture. [Pg.264]

The chilled water (7°C) for the absorber is supplied by an absorption refrigeration unit, using heat recovered from the compressor intercooler as the energy source. Heat for ammonia vaporization, as previously noted, is available at 35°C and is recovered from the secondary gas cooler. The system uses circulating condensate as the energy transfer medium. [Pg.240]

Pebble-Bed Modular Reactor (PBMR) A nuclear reactor technology that utilizes tiny silicon carbide-coated uranium oxide granules sealed in pebbles about the size of oranges, made of graphite. Helium is used as the coolant and energy transfer medium. This containment of the radioactive material in small quantities has the potential to achieve an unprecedented level of safety. This technology may become popular in the development of new nuclear power plants. [Pg.24]

In addition, benzimidazoles containing furyl and aryl substituents at the C-2 position have been synthesized from 1,2-diaminobenzene and the corresponding carboxylic acids imder microwave irradiation in the presence of artificial zeolites and catalytic amounts of DMF, used as the catalyst and energy transfer medium respectively. With this microwave technique, the reaction time was greatly shortened and the products were obtained in higher yields with easier workup than conventional heating methods [21]. [Pg.92]

Many specially designed arc apparatus have been patented for the plasma treatment of petroleum fractions146- 151 Some of these permit cracking gas-liquid mixtures or gas-solid mixtures in continuous process with recycling of undecomposed petroleum. In one such device147 crude oil is mixed with an energy transfer medium (rare gas, alkali metal vapor) and the mixture formed into particles which are fed through the hollow cathode of an electrical arc sustained in the transfer medium. [Pg.19]

Intermolecular Diels-Alder or hetero Diels-Alder reactions have been greatly improved by using microwave technology - again with higher reaction rates and improved yields [3j]. Remarkable improvements in rate acceleration and selectivity enhancement for a variety of intermolecular Diels-Alder reactions have also been accomplished in the past two decades by application of catalysts such as Lewis acids. Recently, many such examples have been reported under microwave conditions in polar solvents or ionic liquids as energy-transfer medium. These reactions have also been developed in open vessels by adsorption of the reactants on mineral solid supports or using neat reactants. [Pg.538]

However, higher yields (85 92%) of 308 were obtained within 4-7 min under MWI in the presence of (NH4)HC03 without solid supports and an energy transfer medium (Scheme 62) (02SC2181). [Pg.42]

Reaction of l,3-dihydro-3-(2-phenyl-2-oxoethylidene)indol-2(l//)-one (820) with 2-aminobenzenethiols (746) to give 8-substituted-2,5-dihydro-l,5-benzothiazepin-2-spiro-3 -3 /f-indol-2 -(l /7)-ones 821 in 49-65% yields was induced under MWI conditions. Ethylene glycol was used as the energy-transfer medium and the reaction required 7-15 min (Scheme 155). However, conventional heating of 820 and 746 in ethanol saturated with hydrogen chloride for 4-6 h gave 51-52% yields (98JCR(S)752). [Pg.108]

Pneumatics works by compressing a quantity of air (or some other gas), filtering it to make sure it is clean, drying it, and sending it through a system with one or more valves. The compressed air is delivered to a mechanical apparatus that can then move a force through a distance. The air is an energy-transfer medium. [Pg.1503]

The basic oven is a simple chamber into which wet or dissolved solids are placed and then dried by the application of heat. The energy-transfer medium may be a hot surface or a gas. The chamber may simply be an enclosed space, or it may contain receptacles for the material to be dried. [Pg.161]

Pyrimido(4, 5-d)pyrimidine derivatives were synthesized by an efficient, facile and solvent-free procedure. These are synthesized by the reaction between aromatic aldehydes, barbituric acid and urea/ thiourea under microwave irradiation. In this process, solid alumina was used as an energy transfer medium (Kategaonkar et al., 2009). [Pg.272]

More recently Andrews and Juzeliunas [6, 7] developed a unified tlieory that embraces botli radiationless (Forster) and long-range radiative energy transfer. In otlier words tliis tlieory is valid over tire whole span of distances ranging from tliose which characterize molecular stmcture (nanometres) up to cosmic distances. It also addresses tire intennediate range where neitlier tire radiative nor tire Forster mechanism is fully valid. Below is tlieir expression for tire rate of pairwise energy transfer w from donor to acceptor, applicable to transfer in systems where tire donor and acceptor are embedded in a transparent medium of refractive index ... [Pg.3018]

The U.S. Department of Energy has funded a research program to develop the Hquid-phase methanol process (LPMEOH) (33). This process utilizes a catalyst such as copper—zinc oxide suspended in a hydrocarbon oil. The Hquid phase is used as a heat-transfer medium and allows the reaction to be conducted at higher conversions than conventional reactor designs. In addition, the use of the LPMEOH process allows the use of a coal-derived, CO-rich synthesis gas. Typical reactor conditions for this process are 3.5—6.3 MPa (35—60 atm) and 473—563 K (see Methanol). [Pg.51]

Steam. The steam system serves as the integrating energy system in most chemical process plants. Steam holds this unique position because it is an exceUent heat-transfer medium over a wide range of temperatures. Water gives high heat-transfer coefficients whether in Hquid phase, boiling, or in condensation. In addition, water is safe, nonpolluting, and if proper water treatment is maintained, noncorrosive to carbon steel. [Pg.226]

Steady-State Fluorescence Depolarization Spectroscopy. For steady state depolarization measurements, the sample is excited with linearly polarized lig t of constant intensity. Observed values of P depend on the angle between the absorption and emission dipole moment vectors. In equation 2 (9), Po is the limiting value of polarization for a dilute solution of fluorophores randomly oriented in a rigid medium that permits no rotation and no energy transfer to other fluorophores ... [Pg.183]

This section is concerned with the UA xtiT — Text) term in the energy balance for a stirred tank. The usual and simplest case is heat transfer from a jacket. Then A xt refers to the inside surface area of the tank that is jacketed on the outside and in contact with the fluid on the inside. The temperature difference, T - Text, is between the bulk fluid in the tank and the heat transfer medium in the jacket. The overall heat transfer coefficient includes the usual contributions from wall resistance and jacket-side coefficient, but the inside coefficient is normally limiting. A correlation applicable to turbine, paddle, and propeller agitators is... [Pg.176]

Kerma (k)—A measure of the kinetic energy transferred from gamma rays or neutrons to a unit mass of absorbing medium in the initial collision between the radiation and the absorber atoms. The SI unit is J/kg. The special name of this unit is the rad (traditional system of units) or Gray (SI). [Pg.278]

Active systems as intermediate storage for cold with an actively moving heat transfer medium. Active systems use at least some energy usually... [Pg.346]


See other pages where Energy transfer media is mentioned: [Pg.186]    [Pg.427]    [Pg.186]    [Pg.75]    [Pg.300]    [Pg.264]    [Pg.264]    [Pg.241]    [Pg.65]    [Pg.75]    [Pg.470]    [Pg.482]    [Pg.111]    [Pg.363]    [Pg.75]    [Pg.551]    [Pg.26]    [Pg.840]    [Pg.1437]    [Pg.3017]    [Pg.3017]    [Pg.3018]    [Pg.460]    [Pg.22]    [Pg.511]    [Pg.388]    [Pg.20]    [Pg.59]    [Pg.470]    [Pg.67]    [Pg.216]    [Pg.104]    [Pg.830]    [Pg.312]   
See also in sourсe #XX -- [ Pg.186 ]

See also in sourсe #XX -- [ Pg.186 ]




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Energy medium

Exchange-mediated energy transfer in viscous media

Transfer medium

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