A pressure-node based dynamic model for simulation and control of aircraft air-conditioning systems

Abstract

The aircraft air-conditioning system, which consumes the engine bleed air to provide stable and comfort environment for passengers, has a high demand of system reliability and energy efficiency. For analyzing system performance and control effect under a wide range of operating scenarios, this paper presents a dynamic model of the aircraft air-conditioning system. A pressure-node based method is proposed to decouple the system architecture, and a modelling framework is established with reflecting the interdependencies between component-level modules. Dynamic sub-models including pressure nodes, heat exchangers and the air cycle machine are built to predict all major dynamics in the system. The model is verified by the measured data of an airborne testing. The predicted temperatures show good agreement with the measured data, of which the average deviations at the compressor outlet and system outlet are 4.60 °C and 3.49 °C, respectively. The effectivity of the proposed model is investigated under various conditions, including different control signal inputs, standard pull up/pull down conditions and an entire flight case. The simulation results indicate that the model can be successfully applied for a wide range of aircraft operating scenarios, and provide insight towards control design and fault detection of the aircraft air-conditioning system.