Cloud depth

The subject of flash fires is a highly underdeveloped area in the literature. Only one mathematical model describing the dynamics of a flash fire has been published. This model, which relates flame height to burning velocity, dependent on cloud depth and composition, is the basis for heat-radiation calculations. Consequently, the calculation of heat radiation from flash fires consists of determination of the flash-fire dynamics, then calculation of heat radiation. 

H = visible flame height S = 2.3 X = flame speed = wind speed d = cloud depth g = gravitational acceleration po = fuel-air mixture density pj = density of air r = stoichiometric air-fuel mass ratio a = expansion ratio for stoichiometric combustion under constant pressure (typically 8 for hydrocarbons)... 

Calculate the flame height from the cloud depth d, gravitational acceleration g, S (P[Pg.279]

The microphysics of the cloud will be represented in terms of the liquid water content, w, rainfall intensity po, updraft velocity w, cloud depth he, and cloud cross-sectional area A. 

To investigate the dependence of molecular abtmdances on extinction, the relative abundances of the two CO isotopes are plotted as a function of Av in Figure 4. Here the mean ratio of CO to C 0 LTE column densities is plotted as a function of Av or cloud depth. This ratio has been computed... 

Freshwater with less than 500 ppm (or 0.05%) dissolved soHds is generally considered to be potable. Rain is the source of freshwater, and its precipitation of >1.3 x 10 m /d over the earth s surface averages about 1.05 m (depth) per year. Extremes range from almost 2ero ia North Chile s desert borderiag the Pacific Coast to > 25.4 m ia some tropical forests and on some high slopes where the high, cold mountains condense floods from the clouds. 

When gas concentrations are high, burning is characterized by the presence of a tall, turbulent-diffusion, flame plume. At points where the cloud s vapor had already mixed sufficiently with air, the vertical depth of the visible burning zone is about equal to the initial, visible depth of the cloud. 

Flash-fire dynamics are determined by a model which relates flame height to a cloud s depth and composition, and to flame speed. On the basis of experimental observations, flame speed was roughly related to wind speed. Flame height can be computed from the following expression ... 

The VIRTIS apparatus (Visible Infrared Thermal Imaging Spectrometer) on board can observe the atmosphere and the cloud layers at various depths (on both the day and the night side of the planet). VIRTIS has also provided data for the first temperature map of the hot Venusian surface. These data have led to the identification of hot spots and thus provided evidence for possible volcanic activity (www.esa.int/specials/venusexpress). 

In Figure 23.7, the bubble, cloud, and emulsion regions are represented by b,c + iv, and e, respectively. The control volume is a thin horizontal strip of height dx through tiie vessel. The overall depth of the bed is Lfl, which is related to the holdup of catalyst, Wcat. The performance equation may be used to determine Wcat for a given conversion /A (and production rate), or the converse. 

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