Dimensionless group 536 INDEX

The performance index is a measure of the quality of the separation. Knox (19) was searching for a criterion that is a purer measure of column performance and criticized the performance index for its dependence on the retention factor and the viscosity. Therefore he defined a dimensionless group, the separation impedance ... 

A sphere of diameter d moving at a constant velocity V through a power-law fluid (density p, flow index, n and consistency coeflflcient, m) experiences a drag force, Fb-Obtain the pertinent dimensionless groups of variables. 

Table 12.1 Definitions of Dimensionless Groups, Thermal Conductivity, T, the Flow Temperature (7 or TJ, the Melt Density, AH the Enthalpy Change, Cp the Heat Capacity, b Exponent of Viscosity Temperature Change, n the Power Law Index, the Viscosity...

A dimensionless molecular retention index Me parameter can be defined as the sum of Mr (relative molecular weight) and a structural increment W. Contained in W are all the additive contributions of the functional groups (see Eq. 4-52) which differ from a hypothetical n-alkane with the same Mr value. According to definition, the W values of the n-alkanes are always equal to zero. In this manner it is possible to estimate the partition coefficients of any given organic compound between a gas and any given liquid or polymer with help of additive structural increments. 

The right hand side of Equation (51) traditionally defines the factor molar refraction [/ ], which is therefore the same as molar electronic polarisability. Since refractive index is dimensionless, [7 ] has the dimensions of volume and is a function of molar volume. It is also an additive and constitutive property, so that the molar refraction of a compound or a group can be calculated by summation of the refraction equivalents of its constituents. Tables of refraction equivalents are to be found in most text books of physical chemistry, for example... 

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