Experimental and Analytical Investigation of Ammonia Absorption intoAmmonia-water Solution: Estimated Interface Concentration

摘要

Ammonia absorption process of ammonia vapor into ammonia water solution has beeninvestigated experimentally, by inserting superheated ammonia vapor into a test cell containing astagnant pool of ammonia water solution of several ammonia mass fractions, C1. Beforecommencing the experiment, the pressure in the test cell corresponds to the equilibrium vapor of theammonia-water system at room temperature. When the valve is opened, mechanical equilibrium isestablished quickly and the ammonia vapor diffuses into ammonia solution [1]. The differencebetween the initial pressure in the vapor cylinder and the initial pressure in the test cell ΔP_iis foundto have a major influence not only on the absorption rate but also on the estimated interfaceconcentration. The interface concentration C_(int)of the cases ΔP_i =50 and 100 kPa exhibits a similartendency, C_(int)decreases rapidly compared to other initial pressures ΔP_i =150 and 200 kPa. On theother hand, the interface concentration C_(int)of the cases ΔP_i =250 and 300 kPa are increasing withinabout 50 sec, then are hardly changing with time. They behave almost in a similar way as of C_(int) =0.27 kg/kg. A correlation which gives the total absorbed mass of ammonia as a function of theinitial concentration, the initial pressure difference and time is derived. In addition, the absorbedmass at no pressure difference could be estimated from the absorbed mass at initial pressuredifference.