Analysis of a Coupling System of Aircraft Environmental Control and Fuel Tank Inerting Based on Membrane Separation 2019-01-1895
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 nowadays. Water vapor can travel across the membrane wall under its pressure difference without phase change, so the dehumidification process consumes no cooling capacity and the cooling capacity of the system increases. This paper first compares the thermodynamic properties of environmental control system based on membrane dehumidification and the environmental control system based on condensation. The results show that the membrane dehumidification system has bigger cooling capacity and lighter weight. For a given cooling capacity requirement of a certain aircraft, the membrane dehumidification system can use less bleed air since the temperature of the outlet air is lower. Nowadays, the fuel tanking inerting system also uses an air separation module to produce nitrogen enriched air based on membrane separation. After the air is dehumidified in membrane environmental control system, its temperature, pressure, humidity ratio and cleanliness meet the requirement of membrane air separation module. This paper conducts a preliminary design and simulation analysis of the coupling system based on given performance requirements. A mathematical model of the coupling system is built, especially the membrane dehumidifier and the membrane air separation module. Comparing with the independent membrane dehumidification environment control system and fuel tank inerting system, which is used onboard nowdays, 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.