Analysis of a Coupling System of Aircraft Environmental Control and Fuel Tank Inerting Based on Membrane Separation

This paper raises a coupling system of aircraft environmental control and fuel tank inerting based on membrane separation. The system applies a membrane dehumidifier to replace water vapor removal unit of heat regenerator, condenser and water separator, which is widely used in conventional aircraft environmental control system (ECS) nowadays. Water vapor can travel across the membrane wall under its pressure difference without phase change, so the dehumidification process consumes no cooling capacity as traditional ECS and the cooling capacity of the new system increases. This paper first compares the thermodynamic properties of ECS based on membrane dehumidification and the traditional ECS based on condensation. The results show that the membrane dehumidification system has larger cooling capacity and lighter weight. For a given cooling capacity requirement, the membrane dehumidification system can use less bleed air since the enthalpy of the outlet air is lower. Besides, the fuel tank inerting system also uses an air separation module to produce nitrogen enriched air based on membrane separation. After the air is dehumidified in membrane dehumidification ECS, its parameters meet the requirement of membrane air separation module. Thus, it is reasonable to combine the two systems together. This paper conducts a simulation analysis of the coupling system. Comparing with the conventional four wheel high pressure de-water ECS and fuel tank inerting system used onboard nowadays, the coupling system has simpler structure and lighter weight. The simulation results show that the coupling system can decrease the fuel penalty by 139.67kg each pack.