Experimental study of ternary NH3-H2O-LiBr absorption cycle combined with membrane separation technique

Modeling absorber by Aspen Plus process monitor, the result shows that the existence of LiBr has negative influence on the process of absorbing NH3. To improve the absorption effect, the membrane separation technique is proposed to separate LiBr from the solution stream entering absorber and retain it in generator as much as possible. In order to test the separation effect, the experiment with a membrane separator containing 3363/3364 ion exchange membrane was carried out. The results show that the separation efficiency of LiBr can reach 90% after once solution cycle in membrane separator, and exceed 98% after twice solution cycle. Based on the separation efficiency in experiment, the Aspen Plus process monitor is used for further simulating and analyzing the new NH3-H2O-LiBr absorption cycle combined with membrane separator. Simulating results indicate that, due to the application of membrane separation technique, the COP of new absorption cycle can be up to 11.08% increase compared with the normal ternary absorption cycle when evaporation temperature ranges in 258.15-279.15 K. And the COP increases with increasing evaporation temperature.