THIN-FILM-COMPOSITE MEMBRANES FOR ON-BOARD INERT GAS GENERATION

AIRCRAFT FUEL TANKS CAN BE PROTECTED FROM FIRE AND EXPLOSION BY FILLING THE VAPOR SPACE ABOVE THE LIQUID FUEL WITH AN INERT GAS SUCH AS NITROGEN. A LOW-MAINTENANCE, MEMBRANE-BASED ON-BOARD INERT GAS GENERATION SYSTEMS (OBIGGS) IS A PROMISING ALTERNATIVE TO THE CURRENTLY USED HIGH-MAINTENANCE LIQUID NITROGEN SYSTEM. HOWEVER, RECENTLY DEVELOPED MEMBRANE-BASED OBIGGS ARE INEFFICIENT IN THEIR REMOVAL OF OXYGEN FROM AIR AND ARE THUS TOO HEAVY FOR PRACTICAL USE IN NITROGEN PRODUCTION. WE PROPOSE TO DEMONSTRATE THE TECHNICAL FEASIBILITY OF PRODUCING AN OBIGGS IN WHICH THE WEIGHT OF ACTIVE MEMBRANE MATERIAL IS DECREASED BY MORE THAN AN ORDER OF MAGNITUDE OVER PRESENT MEMBRANE-BASED OBIGGS. A NOVEL, EXCEEDINGLY THIN MEMBRANE CURRENTLY UNDER DEVELOPMENT AT BEND RESEARCH FOR A RELATED APPLICATION WILL BE CHEMICALLY MODIFIED TO OBTAIN HIGH OXYGEN PERMEATION RATES. THESE ULTRATHIN MEMBRANES HAVE VERY HIGH GAS THROUGHPUT PER UNIT AREA, AND THUS LESS MEMBRANE MATERIAL IS REQUIRED THAN IN CURRENT MEMBRANEBASED OBIGGS FOR THE SAME OVERALL PERFORMANCE. OUR ENGINEERING CALCULATIONS SHOW THAT AN ULTRATHIN MEMBRANE WITH THE OPTIMAL CHEMISTRY WILL POTENTIALLY RESULT IN A 300-FOLD WEIGHT REDUCTION OVER CURRENT OBIGGS.