COALA

In order to meet the requirements of economic and ecological performances from airline companies and civil society in general, aircraft manufacturers propose to resort to more efficient systems, leading to less fuel consumption. This impacts the aeronautical air conditioning, and can be applied also to railway sector. Thus, weight reduction, compactness improvement and better efficiency is a great challenge for air conditioning systems. The air conditioning pack is equipped with a condenser and a water extractor that allows drying the air before its expansion in the turbine of the air-conditioning system in order to avoid the condensation of droplets, which would damage the blades of the turbine, and to keep the cockpit and cabin from fogging on ground operation and low altitudes. The water extraction loop is about 25% of the mass and volume of the air conditioning pack, and also contributes to its performances. A better understanding of the physical phenomena in this loop is therefore crucial for optimizing the system. The aims of the COALA Project (COndensation And Liquid Atomization), is to improve the physical understanding and the prediction of the condensation and of the atomization of liquid films downstream the water extractor. This project focuses on two distinct phenomena: . The condensation and liquid film formation in the mini channels of the condenser core . The liquid film stability in the mini channels and atomization These two distinct problems will be studied separately but in complementary ways by the Institut de Mécanique des Fluides de Toulouse. A numerical study is proposed in the project to quantify the condensation rate in the milimetric channels. An experimental study aims at studying the atomization into droplets of the liquid film by an airstream to quantify the velocities and the droplet size distributions at the outlet of the condenser. The modeling proposed by IMFT concerning the condensation rate in a mini channel and the droplet size distribution will be used by Liebherr to be implemented in a 0D model of the air-conditioning loop or in a 3D model of the water separator. By joining academic skills (Institute of Fluid Mechanics of Toulouse) and industrial skills (Liebherr Aerospace Toulouse), this collaborative project targets the energetic optimization of air-conditioning system in aircrafts or trains.