Experimental and Analytical Investigation of Ammonia Absorption into Ammonia-Water Solution: Free Absorption

Abstract

Absorption phenomenon of ammonia vapor into ammonia water solution has been investigated experimentally, by allowing superheated ammonia vapor to flow into a test cell containing a stagnant pool of ammonia water solution. Before commencing the experiment, the pressure in the test cell P1i, corresponds to the equilibrium vapor of the ammonia-water system at room temperature and initial mass fraction Ci. When the valve is opened, mechanical equilibrium is established quickly and the pressure in the test cell becomes equal to that of the ammonia vapor cylinder. The difference between the initial pressure in the vapor cylinder and the initial pressure in the test cell ΔPi is found to have a major influence on the absorption rate [1]. The interface temperature can be estimated for a transient case, by help of an inverse solution proposed by Monde [2]. The interface concentration Cint obtained by measured ammonia vapour pressure and the estimated interface temperature. The main objective of this study is to investigate the effect of the initial pressure difference and the initial concentration on the interface concentration. A correlation which gives the interface concentration as a function of the initial concentration, the initial pressure difference and time is derived. In addition, the absorbed mass at no pressure difference could be estimated from the absorbed mass at initial pressure difference.