Liquid surface area/volume

E] Gas absorption aud desorption from water aud organics plus vaporization of pure liquids for Raschig riugs, saddles, spheres, aud rods, dp = nominal pacldug size, Cp = dry pacldug surface area/volume, = wetted pacldug surface area/volume. Equations are dimensionally consistent, so any set of consistent units can be used. <3 = surface tension, dynes/cm. 

Frank in dogs. The most likely explanation is that the model does not account for chemical reactions of ozone in the mucus and epithelial tissue. Another problem is that the nose is believed to behave more like a scrubbing tower with fresh liquid at each level, inasmuch as the blood supply is not continuous for the entire length of the nose, as assumed in the model. Neglecting the surface area, volume, flow, and thickness of the mucus layer in the nose will probably also give erroneous results for soluble gases with a small diffusion coefficient in mucus and for singlebreath inhalations of a low concentration of any gas. 

The first two methods are widely used just for laboratory-scale applications, since there are limitations for their use at larger scales. In surface aeration, the oxygen transfer rate is related to the liquid surface area (gas-liquid interface). When the culture scale is increased, maintaining constant geometric proportions, the volume increases with the third power of a characteristic linear dimension of the system, whereas the surface area increases with its square. 

Liquid-solid mass transfer is typically not limiting due to the small particle size resulting in large particle surface area/volume of reactor, unless the concentration of the particles is very low, and or larger particles are used. In the latter case, intraparticle mass-transfer limitations would also occur. Ramachandran and Chaudhari (Three-Phase Catalytic Reactors, Gordon and Breach, 1983) present several correlations for liquid-solid mass transfer, typically as a Sherwood number versus particle Reynolds and Schmidt numbers, e.g., the correlation of Levins and Glastonbury [Trans. Inst. Chem. Engrs. 50 132 (1972)] ... 

The and denote the integral exponents of D in the respective summations, and thereby explicitly define the diameter that is being used. and are the number and representative diameter of sampled drops in each size class i For example, the arithmetic mean diameter, is a simple average based on the diameters of all the individual droplets in the spray sample. The volume mean diameter, D q, is the diameter of a droplet whose volume, if multiplied by the total number of droplets, equals the total volume of the sample. The Sauter mean diameter, the diameter of a droplet whose ratio of volume-to-surface area is equal to that of the entire sample. This diameter is frequendy used because it permits quick estimation of the total liquid surface area available for a particular industrial process or combustion system. Typical values of for pressure swid atomizers range from 50 to 100 am. 

Selection of the ideal support for a liquid membrane requires careful consideration of the characteristics of the particular separation such as gas or liquid phase, pressure, temperature, and chemical nature of the phases in contact with the membrane. However, a few generalizations can be made. The ideal support should be thin (< 100 pm), have a high porosity (> 50%), have a mean pore size of less than 0.1 pm, have a narrow pore size distribution, and be available in geometries that will produce permeators with a high surface area /volume ratio. 

There are fewer studies on the retention mechanism for open tubular columns but the theory presented for packed columns should be equally applicable. For films of normal thickness open tubular columns have a large surface area/volume ratio and the contribution of interfacial adsorption to retention will be significant for those solutes with limited solubility in the stationary phase [42]. Interfacial adsorption was shown to affect the retention reproducibility of polar solutes on non-polar stationary phases of different film thicknesses and the retention index values of solutes on polar stationary phases due to liquid phase interfacial adsorption of the n-alkane retention index standards [184,188,193-197]. 

In use, the ELM Is dispersed In a continuous phase and separates two miscible phases. Under agitation, the ELM phase separates Into spherical globules of emulsion which have typical diameters of 10 ym to 1 mm. Each globule contains many droplets of encapsulated Inner or receiving phase with a typical size of 1 to 10 ym In diameter. The formation of many globules of emulsion produces large surface area/volume ratios of 1000 to 3000 mVm for very rapid mass transfer (20). Due to this dispersed emulsion configuration, ELMs or liquid surfactant membranes are commonly referred to as double emulsions. 

Foam granulation takes advantage of the tremendous increase in the liquid surface area and volume of polymeric binder foams to improve the distribution of the water/binder system throughout the powder bed of a solid dose pharmaceutical formulation. 

The volume of the column is more than 3 times larger, so the gas/liquid surface area may be larger by a factor of about 1.5. The mass transfer coefficient will not be much different, so it is not likely that mass transfer is rate determining in this upflow column, if it was not so in the stirred tank. 

After inserting A Ml, = nu,out — nujn sind AA = avAAVR(ay = gas-liquid surface area-to-reactor volume) and recalling the definition of Op (particle area-to-reactor volume) as in Equation 6.8, Equation 6.16 is transformed to... 

After inserting Equation 6.2 and the definition of Hy (gas-liquid surface area-to-reactor volume), we obtain... 

Interfacial area/reactor volume gas-liquid surface area to reactor volume... 

Middleton indicates that for his regime 1 (very slow reaction), where Rl is little affected by the chemical reaction, the interface surface area per unit volume, a, is of little importance since the reaction takes place in the bulk liquid phase, so a bubble colunm is the typical reactor of choice. For Middleton s regimes 11, IV, and V—diflfusional control, very fast reaction, and instantaneous reaction, respectively—both high a and k [ are needed, so a stirred tank is the typical reactor recommended. In regime III—reaction in the mass transfer film—the most important variable is the interface area, so a packed column yielding much liquid surface area may be appropriate. 

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