Evaporation of liquids

E] Evaporation of liquids. Use with log mean concentration difference. See item above. Better fit for gases. 

Power dissipation can lead to temperature increases of up to 40°C in the mass. Note that evaporation of liquid as a result of this increase needs to be accounted for in determining liquid requirements for granulation. Liquid should be added through an atomizing nozzle to aid uniform hquid distribution in many cases. In addition, power intensity (kW/kg) has been used with some success to judge granulation end point and for scale-up, primarily due to its relationship to granule deformation [Holm loc. cit.]. Swept volume ratio is a preliminary estimate of expected power intensity. 

Evaporation of liquid to form vapour is accompanied by a considerable increase in volume. For example, at atmospheric pressure one volume of water will generate 1600 volumes of steam. Similarly 4.54 litres of gasoline will yield 0.93 m of neat vapour on complete vaporization. The reverse process, condensation, is accompanied by a considerable - and often rapid - decrease in volume. As a result ... 

Briscoe F. and P. Shaw, 1980, Spread and Evaporation of Liquid, Progress in lowryv and Combined Sciences, 6, 2, 127-140. 

Our knowledge of gas behavior helps us interpret the evaporation of liquids. We have considered, thus far, vaporization of a liquid at its usual... 

Mathias (1896) found, in his experiments on the latent heat of evaporation of liquid C02, S02, and N20 up to the critical points, that the curve Lc = /(T) cuts the T axis at right angles at the point T = TK. Thence at the critical point... 

S03/air can be raised from sulfur burning and subsequent oxidation to S03 or S03 can be stripped from 65 % oleum with dry air or S03 can be obtained by evaporation of liquid-stabilized S03, subsequently mixed with dry process air. 

Ranz and Marshall 51 have carried out a comprehensive study of the evaporation of liquid drops and confirm that equation 10.231 correlates the results of a number of... 

Maisi-x. D.S. and Sherwood, T.K. Chem. Eng. Prog. 46 (1950) 131 Evaporation of liquids into mrhulenr gas streams. 

Determination of the wet-bulb temperature. Equation 13.8 gives the humidity of a gas in terms of its temperature, its wet-bulb temperature, and various physical properties of the gas and vapour. The wet-bulb temperature is normally determined as the temperature attained by the bulb of a thermometer which is covered with a piece of material which is maintained saturated with the liquid. The gas should be passed over the surface of the wet bulb at a high enough velocity (>5 m/s) (a) for the condition of the gas stream not to be affected appreciably by the evaporation of liquid, (b) for the heat transfer by convection to be large compared with that by radiation and conduction from the surroundings, and... 

Under special conditions sulfur cations with up to 56 atoms have been observed [209]. Evaporation of liquid sulfur and cooling the vapor in an atmosphere of a cold buffer gas (He) at low pressures followed by adiabatic expansion into the vacuum of a mass spectrometer and El ionization produced mass spectra of clusters of sulfur molecules with m/e ratios up to ca. 1800. The intensity pattern shows that the species (Ss)h are most abundant n = 1-7) followed by (Sy)(S8)n-i clusters and (S6)(Ss)h-i clusters. The latter have the same mass as (Sy)2(S8) -2 clusters see Fig. 34. Thus, the composition of the clusters reflects the composition of hquid sulfur near the melting point which contains Sg, Sy and Se molecules as the majority species [34, 210]. 

Fig. 34 Mass spectrum of sulfur clusters obtained by evaporation of liquid sulfur followed by cooling and adiabatic expansion of the vapor [209]. The figures at the peaks give the number of Sg molecules which represent this particular mass...

This can explain why hydrogen flow rate has little effect on liquid phase distribution in the catalyst bed and on conversion. At the same time, higher flow rates of warm hydrogen intensify evaporation of liquid in the inert layer and remove the resulting vapor out of the reactor, leading to the decrease in liquid content in the inert layer. 

During evaporation of liquid stibine at — 17°C, a relatively weak and isothermal explosive decomposition may occur. Gaseous stibine at ambient temperature may propagate an explosion from a hot spot on the retaining vessel wall, and it auto-catalytically decomposes, sometimes explosively, at 200°C. 

An important extension of this relationship is its application to the evaporation of liquids into a given atmosphere, such as air. Consider the evaporation of water into air (Xo2 = 0.21 and Xy, = 0.79). Suppose the air is at 21 °C. If the water is in thermal equilibrium with the air, also at 21 °C, its vapor at the surface must have a vapor pressure of 0.0247 atm (from standard Steam Tables). However, if the water and the air are at the same temperature, no further heat transfer can occur. Therefore no evaporation can take place. We know this cannot be tme. As discussed, in the phenomenon of evaporative cooling , the surface of the liquid water will have to drop in temperature until a new equilibrium p(T) can satisfy the conservation laws, i.e. 

Thus at 100 % relative humidity the air atmosphere contains the most mass of water vapor possible for the temperature T X,. No further evaporation of liquid water is possible. 

In the study of steady evaporation of liquid, we derived in Equation (6.34), and given as Equation (9.6),... 

The mass flux arising from the evaporation of liquid droplets is significant to fire scaling applications. Such scaling has been demonstrated by Heskestad [11], and specific results will be discussed later. As a first approximation, independent monodispersed droplets of spherical diameter, D, and particle volume density, can be considered. 

In addition to the electrolysis method for fractionating water, the distillation method could also be utiUzed by the imidirectional evaporation of a saturated brine at a sufl dently low temperature. While the theo-rectical efl ciency of the process is less than that for the evaporation of liquid hydrogen itself, the experimental technique is much simpler and the process could be operated continuously with very little attention. 

In many natural (raindrops, fogs, river water fall) and industrial systems (sprays, oil combustion engines, cleaning processes), one encounters liquid drops. The rate of evaporation of liquid from such drops can be of importance in the function of these systems. 

Extensive investigations on evaporation of liquid drops (free-hanging drops, drops placed on solid surfaces) have been reported in the current literature (Birdi, 2002). These drops have been analyzed as a function of... 

In industrial practice the foaming processes are sometimes divided into chemical and physical processes. Chemical processes are those where the formation of gas takes place by decomposition of an unstable inorganic or organic compound or by a chemical reaction. Physical processes mean such techniques where the foaming gases are pumped into the polymer or are formed by the evaporation of liquids. 

Apparent (virtual) teaks quantities of gas will be liberated from hollovi/s and cavities inside cast parts, blind holes and joints (also due to the evaporation of liquids)... 

These compressed air nebulizers produce polydisperse aerosols. After the aerosol is produced, the size distribution may change due to evaporation of liquid from the droplets. In addition, the particles may be electrically charged due to an ion imbalance in the droplets as they form if such charges become further concentrated due to evaporation, the particle may break up into smaller particles. Thus electrical neutralization of the aerosol, for example, by exposure to a radioactive source, is usually necessary to prevent electrostatic effects from dominating the particle motion, coagulation, and other behavior. 

Boron nitride and titanium diboride coatings are used on graphite for the evaporation of liquid aluminum. 

Evaporation of liquid water forms water vapor which is a gas in the closed container. After a while, water vapor molecules start collisions with each other and with the water s surface then they turn into water. Therefore, evaporation and condensation are a reversible process in a closed container. Reversible processes are represented by Irriversible processes are represented by... 

This relation has been used for the calculation of diffusion coefficients by the rate of evaporation of liquid droplets suspended in a still gas (S9, p. 17). Clearly Eq. (122) does not describe the situation properly if the diffusion produces free convection owing to changes in density. 

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