Radiative flow

Figure 6.3.6 further compares and of lean to stoichiometric methane/air mixtures for all five cases— plug flow, potential flow, asymmetric plug flow, radiative plug-flow, and radiative asymmetric plug-flow. The... 

In fluids, the atoms and molecules may themselves migrate and set up convection currents or flow. Radiative heat transfer, on the other hand, requires no medium for transport. Thermal energy is carried with light-wave packets, called photons, and heats up the body when the body absorbs the photons. Whereas the phonon conductivity dominates heat transfer in the glassy state, transfer of heat in molten glass tanks is mostly due to radiative transfer and to some extent by convective and conductive transfer. 

In the laser flash method, the heat is put in by laser flash instead of electric current in the stepwise heating method mentioned above. Thus this method may be classified as a stepwise heating method. A two-layered laser flash method was developed by Tada et al. " The experimental method and the data analysis, including a case involving radiative heat flow, are described in detail in the review article by Waseda and Ohta. A thin metal plate is placed at the surface of a melt. A laser pulse is irradiated onto a metal plate of thickness / having high thermal conductivity. The sample liquid under the metal plate and the inert gas above the plate are designated as the third and first layers, respectively. The temperature of the second layer becomes uniform in a short time" and the response thereafter is expressed by... 

Table 1. Activation energies and ratios of the preexponential factors to the radiative rate constants (A/kp) for the photoisomcrization of BMPC in several solvents. Solvent dielectric constants at room temperature, e [65], and viscous flow activation energies, Eri [66], are shown too.

The steady-state total heat flow (Q) at r = Rs is determined by using Fourier s law and adding the radiative term ... 

Molecular rotors are fluorophores characteristic for having a fluorescent quantum yield that strongly depends on the viscosity of the solvent [50], This property relies on the ability to resume a twisted conformation in the excited state (twisted intramolecular charge transfer or TICT state) that has a lower energy than the planar conformation. The de-excitation from the twisted conformation happens via a non-radiative pathway. Since the formation of the TICT state is favored in viscous solvents or at low temperature, the probability of fluorescence emission is reduced under those conditions [51]. Molecular rotors have been used as viscosity and flow sensors for biological applications [52], Modifications on their structure have introduced new reactivity that might increase the diversity of their use in the future [53] (see Fig. 6.7). 

Harkelroad, M., Quintiere, J., Walton, W., "Radiative Ignition and Opposed Flow Flame Spread Measurements on Materials", Report No. DOT/FAA-CT-83/28, FAA Technical Center, Atlantic City Airport, N.J., 1983... 

Convective heating in fire conditions is principally under natural convection conditions where for turbulent flow, a heat transfer coefficient of about 10 W/m2 K is typical. Therefore, under typical turbulent average flame temperatures of 800 °C, we expect convective heat fluxes of about 8 kW/m2. Consequently, under turbulent conditions, radiative heat transfer becomes more important to fire growth. This is one reason why fire growth is not easy to predict. 

DGE a AC AMS APCI API AP-MALDI APPI ASAP BIRD c CAD CE CF CF-FAB Cl CID cw CZE Da DAPCI DART DC DE DESI DIOS DTIMS EC ECD El ELDI EM ESI ETD eV f FAB FAIMS FD FI FT FTICR two-dimensional gel electrophoresis atto, 10 18 alternating current accelerator mass spectrometry atmospheric pressure chemical ionization atmospheric pressure ionization atmospheric pressure matrix-assisted laser desorption/ionization atmospheric pressure photoionization atmospheric-pressure solids analysis probe blackbody infrared radiative dissociation centi, 10-2 collision-activated dissociation capillary electrophoresis continuous flow continuous flow fast atom bombardment chemical ionization collision-induced dissociation continuous wave capillary zone electrophoresis dalton desorption atmospheric pressure chemical ionization direct analysis in real time direct current delayed extraction desorption electrospray ionization desorption/ionization on silicon drift tube ion mobility spectrometry electrochromatography electron capture dissociation electron ionization electrospray-assisted laser desorption/ionization electron multiplier electrospray ionization electron transfer dissociation electron volt femto, 1CT15 fast atom bombardment field asymmetric waveform ion mobility spectrometry field desorption field ionization Fourier transform Fourier transform ion cyclotron resonance... 

Radiative Transfer., 102, 62 (2006). Characterization of Spherical Particles using High-Order Neural Networks and Scanning Flow Cytometry. 

Igumenshchev, I.V., Narayan, R., Abramowicz, M.A. (2003), Three-dimensional magnetohydrodynamic simulations of radiatively inefficient accretion flows , ApJ 592, 1042. 

The buoyant gas flow above the fire, including any flames, is typically referred to as the fire plume (see Figure 5-8). Flame temperatures typically range from 900°C to 1200°C, and will vary with the type of fuel, ambient conditions, and oxygen availability. Temperature variations result from the amount of soot particles within the flame (which absorb energy and allow for convective or radiative heat transfer) (Drysdale, 1998). In general, the sootier the flame, the cooler its temperature. 

Data by McCaffrey (1995) show that the radiative fraction decreases for jet flames. Based on laboratory-scale tests, as the jet velocity increases the radiative fraction decreases. Although the aerodynamics of the flow have a significant effect on the radiation from the flame, the experimental data show that a radiative fraction of 0.4 represents a conservative maximum value for most fuels and conditions. If a more detailed or less conservative analysis is desired, Beyler (2002) presents experimental data for radiative fractions for the conditions discussed above. 

Current and future combustor applications require increased energy release with reduced chamber volume, increased equilibrium temperature, multiphase reacting flows with radiative heat transfer, and sometimes even with electric and magnetic fields. A thorough understanding of the basic physical and chemical... 

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