ABSTRACT
Mass transfer phenomena are encountered in everyone’s daily routine. Dissolution of sugar in a cup of tea, percolation of water through roast and ground coffee granules to prepare an aromatic brew in a coffee maker, perception of rich aroma from the vapors above a cup of coffee, refrigeration and air conditioning are all the different forms of mass transfer in day-to-day life. However, moving a mass of fluid or solid from one place to another is not mass transfer. Similar to any transport process, the mass transfer also occurs as a result of the balance between two forces: resisting force and driving force. While proximity (distance) between the components acts as the resisting force, concentration gradient acts as the driving force. Concentration gradient (ΔC) is the difference in concentrations (C 1− C 2) of a component with respect to different positions within a system (Figure 6.1). Thus, mass transfer can be defined as the transport of one component in a mixture from a region of higher concentration to that of a lower concentration.
