Gilliland-Sherwood equation

Sublimation rates of pure solids into turbulent air streams have been successfully correlated by the Gilliland-Sherwood equation(102) ... 

Examples of mass transfer under high vacuum are distillation of thermally unstable organic compounds, high-vacuum freeze drying, vacuum concentration of fruit juices, vacuum drying of coffee concentrate, vacuum purification of molten metals, etc. The mechanism of mass transfer in the concentration of fruit juices can be adequately described by the Gilliland-Sherwood equations (Gl), since the mean free path is negligible relative to the dimensions of the vessel at the pressures used. These equations show that the mass transfer coefficient is inversely proportional to the pressure. By extrapolation to very low pressures, it should be possible... 

Gilliland-Sherwood correlation A dimensionless equation used to determine the mass transfer in gas absorption and relates the Sherwood number, Reynolds number, and Schmidt number ... 

In defining a 7-factor (jd) for mass transfer there is therefore good experimental evidence for modifying the exponent of the Schmidt number in Gilliland and Sherwood s correlation (equation 10.225). Furthermore, there is no very strong case for maintaining the small differences in the exponent of Reynolds number. On this basis, the /-factor for mass transfer may be defined as follows ... 

Sherwood and Pigford(7) have shown that if the data of Gilliland and SHERWOOD<36) and others 35 38,395 are plotted with the Schmidt group raised to this power of 0.67. as shown in Figure 10.14, a reasonably good correlation is obtained. Although the points are rather more scattered than with heat transfer, it is reasonable to assume that both jd and 7/, are approximately equal to 0. Equations 10.224 and 10.226 apply in the absence of ripples which can be responsible for a very much increased rate of mass transfer. The constant of 0.023 in the equations will then have a higher value. 

Gilliland and Sherwood s data118, expressed by equation 12.23, are shown in Figure 12.4 for a number of systems. To allow for the variation in the physical properties, the Schmidt Group Sc is introduced, and the general equation for mass transfer in a wetted-wall column is then given by ... 

The Sherwood-Gilliland correlation in the form of equation (2-74) may be used to estimate the binary mass-transfer coefficients in the vapor phase. Calculate the Reynolds number ... 

Gilliland and Sherwood measured evaporation rates of various liquids into a turbulent air stream in a wetied-wall column for both cocurrent and coumercurrent flows and proposed the equation... 

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