Two main cooling systems are installed in a modern passenger aircraft. An air cycle system controls the temperature in the fuselage taking care of the heat loads generated by passengers, electronic equipment and solar radiation. A second cooling system is present to remove heat from the installed galleys to meet the required temperature for storage of food and beverages. The development of this system towards weight reduction and efficiency optimisation has become more relevant in the last decade caused by rising health, comfort and reliability demands. This results in increased complexity and performance requirements. In this paper a direct-evaporating CO2 system for galley cooling is discussed using a non-linear model written in the language Modelica. Integrating a direct-evaporating system in an aircraft requires an exact analysis of the operating conditions. The boundary conditions can vary significantly in temperature and humidity inside and outside the aircraft. The heat that is removed from the galleys by the refrigerant is rejected to the ambient air at the gas cooler. The presented paper shows the advantages of transient numerical simulations. Conditions which cannot be adjusted at existing test rig can be investigated having the opportunity to see even processes like the mass movement in the system or the quality change in the heat exchangers. Furthermore it is possible to investigate operating conditions which could lead to damage of the test rig. Moreover intensive parameter studies to get for example a characteristic diagram for the COP can be performed. The charge level study has the great advantage that the change of the discharge temperature at the compressor can be investigated before experimental studies take place. Effort has to be put in some numerical issues. The simulation of the presented three consumer model has required some time to find for example the correct discretisation to get correct results on the one hand and a stable and fast model on the other hand. The simulation around the critical point of CO2 is still a problem.


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    Title :

    Numerical simulation of an aircraft CO2 supplemental cooling system


    Contributors:
    Vasel, J. (author) / Schmitz, G. (author)


    Publication date :

    2007


    Size :

    10 Seiten, 13 Bilder, 6 Quellen




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English





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