Experimental and analytical investigation of ammonia vapor absorption into ammonia-water solution アンモニア水溶液へのアンモニア蒸気の吸収過程に関する研究
Experimental and analytical investigation of ammonia vapor absorption into ammonia-water solution
Hatem Mustafa Muftah Zawagy
ハーテム ムスタファ ムフタ ザワキ
Absorption phenomenon of ammonia vapor into ammonia water solution has been investigated experimentally, by inserting superheated ammonia vapor into a test cell containing a stagnant pool of ammonia water solution. Before commencing the experiment, the pressure in the test cell corresponds to the equilibrium vapor of the ammonia-water system at room temperature. 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 is found to have a major influence on the absorption rate. The main objective of this study is to investigate the effect of this initial pressure difference on the absorption rate of ammonia vapor. A correlation which gives the total absorbed mass of ammonia as a function of the initial concentration, the initial pressure difference and time is derived to estimate the mass absorption rate of ammonia vapor into ammonia-water solution. The absorbed mass at no pressure difference could be estimated from the absorbed mass at initial pressure difference. In addition the absorption process has been visualized by a Mach-Zehnder interferometer and the obtained fringes have been analyzed to get the concentration distribution together with that obtained by theoretical solution in which ammonia concentration at the interface changes with time. The obtained optical images allowed us to distinguish between two layers with different speeds of fringes propagation. The layer with slow propagation of fringes reflects pure mass diffusion with negligible heat effect especially after long time from starting the absorption, while the layer with fast propagation of fringes reflects a thermal controlled diffusion.