Removal of carbon dioxide and water using a solid amine adsorption bed for extended space flight

Abstract

An enhanced solid amine based regenerative CO$\sb2$ and H$\sb2$O removal system is being used for the shuttle extended duration orbiter (EDO) missions. A computer model was developed to predict the adsorption of carbon dioxide and water onto a polyethyleneimine coated acrylic ester substrate (designated HSC+). Nineteen experimental adsorption breakthrough tests were conducted using a test bench at NASA/Johnson Space Center, Houston, Texas. CO$\sb2$ and H$\sb2$O adsorption equilibrium data was obtained. Analytical equations were developed to predict the overall water and carbon dioxide equilibrium on HSC+. This data was then used to develop a dynamic model which predicts the rate at which carbon dioxide and water are adsorbed. The model was based on a finite difference method to obtain a system of ordinary differential equations which were solved simultaneously using a fourth order Runga-Kutta method. Comparison of the breakthrough curves with the model for both CO$\sb2$ and H$\sb2$O show that the model predicts both CO$\sb2$ and H$\sb2$O adsorption rates at various conditions accurately.