Manifold optimization for the ATLAS Transition Radiation Tracker CO2 cooling system

Inlet and outlet manifolds represent a crucial part of the CO2 cooling system for the ATLAS Transition Radiation Tracker (TRT) as long as they determine the flow homogeneity in the detector and the pressure losses where the hydraulic diameters are the smallest. An experiment was done on real scale prototypes with air. It is shown how the nozzle flow resistance coefficient variation along the inlet manifold simplifies its optimization compared to the outlet manifold. A flow model was developed to be able to optimize the system for turbulent flows from 25 m^3/h to 75^3/h and adapt the results to CO2. For 50 m^3/h, a flow variation lower than 24% for both manifolds with an overall pressure drop of 92 mbar was obtained.