Letter Symbols for Chemical Engineering

Ordinarily, the same symbol is used for a given physical quantity regardless of its units. Subscripts, superscripts, and lower- and upper-case letters can be employed to give special meanings. The nomenclature should be consistent with common usage (a list of recommended symbols for chemical engineering quantities is presented in Table l).t... 

Symbols for (physical) quantities, be they variables or constants, are given by a single character (generally Latin or Greek letters) and are printed in italics, e.g., F (force), p (pressure), p (chemical potential), k (Boltzmann constant). Further differentiation is achieved by the use of subscripts and/or superscripts these are printed in italics if it concerns the symbol of a quantity, otherwise in roman type, e.g., cp (specific heat at constant pressure), hp (Planck s constant), Ffu (surface dilational modulus). For clarity, symbols are generally separated by a (thin) space, e.g., F=ma, not ma. Some generally accepted exceptions occur, such as pH, as well as symbols (or two letter abbreviations, rather) for the dimensionless ratios frequently used in process engineering, like Re for Reynolds number and Tr for Trouton ratio (in roman type). 

Dynamic viscosity, also absolute viscosity. The usual symbol for dynamic viscosity used by mechanical and chemical engineers is the Greek letter mu ( ). The symbol r] is used by chemists, physicists, and the International Union of Pure and... 

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