(142ah) Rivulet Flow of Liquid in Inclined Pipelines

Packed towers are widely used in process industries for carrying out unit operations such as distillation, absorption, water cooling and catalytic gas-liquid reactions in which flowing gas needs to be brought into intimate contact with liquid flowing on the particles in the form of rivulets or films. Wetting efficiency, defined as the ratio of gas-liquid contact area to the particle surface area, directly affects the mass transfer rates. It has been observed that wetting efficiency can be less than one depending on the equipment variables (such as type of liquid distributor, particle shape, size, materials of construction, cocurrent or counter current flows) as well as operating variables (such as liquid and gas flow rates). Hydrodynamics of packed beds is generally analyzed by considering the bed to consist of parallel tortuous tubes through which gas and liquid may flow either co- or counter-currently. To develop an understanding of the wetting efficiency in packed towers, liquid flow through a single inclined tube by gravity in presence of gas flowing in co- or counter current flow is investigated. Width of liquid rivulet flowing by gravity is measured as a function of liquid and gas flow rates. Effect of pipe inclination , pipe diameter, liquid viscosity and surface tension on rivulet width are also investigated. The observations are analyzed through the concept of friction factor.