Empirical formula for the mass flux in chemical absorption of CO₂ with ammonia droplets

Highlights: • First ever formula for absorption mass flux of CO₂ using ammonia droplets. • Expressed in terms of instantaneous local concentrations only, without time. • Easily applicable to the case of poly-dispersed droplets and non-uniform gas field. • Applicable for any inlet conditions at any instant and positions in the reactor. • Universal formula, applicable to almost any chemical absorption process. - Abstract: Chemical absorption of CO₂ with a droplet of aqueous NH₃ was numerically analyzed, and an empirical formula was derived to describe the instantaneous absorption mass flux as a function of instantaneous concentration conditions and other constant operating parameters. The proposed formula fit the numerical results excellently over a wide variation of initial or control parameter values and throughout the absorption process at different instants. The formula will be very useful to analyze the efficiency of an absorption reactor in which distribution of poly-dispersed droplets is nonuniform, and is applicable to various liquid absorption processes after appropriate modification of parameter values.