Manifolds optimization and pressure drops in the ATLAS TRT CO 2 cooling system Joël Grognuz

Manifolds optimization, Joël Grognuz Manifold experiment Full scale straight half manifold (2m, 40 holes for inlet, 3m, 48 holes for outlet) manufactured from aluminum U profiles with plexiglas glued on top. Full scale straight half manifold (2m, 40 holes for inlet, 3m, 48 holes for outlet) manufactured from aluminum U profiles with plexiglas glued on top. For fixed Q in/out, measure  p nozzle (z), and q nozzle (z) For fixed Q in/out, measure  p nozzle (z), and q nozzle (z) Water U manometers Outlet manifold mock-up Pump Wisag flow-meter for Q out 48 holes under the rail ezez Holes for p static measurements

Manifolds optimization, Joël Grognuz Manifold experiment Inlet first results: Flux variation of 40 % Flux variation of 40 % q nozzle measurements are good for  p nozzle > 12mbar: q nozzle measurements are good for  p nozzle > 12mbar: q nozzle (z) may: q nozzle (z) may:  be increasing  have a local minimum  be decreasing Increasing ! depending on holes sizes, Q in and friction losses.

Manifolds optimization, Joël Grognuz Model  depends on the geometry of the flow at the nozzle: for inlet manifolds, the resistance increases with the flow perpendicular to the nozzle, whereas the opposite happens for outlet manifolds!  depends on the geometry of the flow at the nozzle: for inlet manifolds, the resistance increases with the flow perpendicular to the nozzle, whereas the opposite happens for outlet manifolds! Inlet manifold Outlet manifold Nozzle flow resistance coefficient: Nozzle flow resistance coefficient:

Manifolds optimization, Joël Grognuz Model validation (air) Inlet Inlet (  calibrated from 3.7 mm diameters, Q_{in}=37.5 m 3 h -1 ) (  calibrated from 3.7 mm diameters, Q_{in}=37.5 m 3 h -1 ) Outlet (  calibrated from 2 mm diameters, Q_{in}= 25 m 3 h -1 ) Outlet (  calibrated from 2 mm diameters, Q_{in}= 25 m 3 h -1 ) q variation = 11%

Manifolds optimization, Joël Grognuz Dimensioning of TRT manifolds Characteristics: Characteristics:  q nozzle (z) unlike  p nozzle (z) fairly constant with varying Q in/out or . Changes in model for CO 2 : Changes in model for CO 2 :  density:  kinematic viscosity:  D’Arcy friction factor (from chart for laminar and turbulent flows):  Flow resistance coefficient with zero perpendicular flux:  Manifold cross-section: 52 x 6.35 or 42 x 7 42 x 7.35 mm 52 x 6.35 or 42 x 7 42 x 7.35 mm Poiseuille flow (laminar) special setup to measure  0 :

Manifolds optimization, Joël Grognuz Optimized holes distributions (CO 2 ) Inlet (q nozzle variation = 12%) Inlet (q nozzle variation = 12%) Outlet (q nozzle variation = 24%) Outlet (q nozzle variation = 24%)

Manifolds optimization, Joël Grognuz Pressure drops in system (best case)

Manifolds optimization, Joël Grognuz Pressure in system (best case)

Manifolds optimization, Joël Grognuz Pressure drops in system (worst case)

Manifolds optimization, Joël Grognuz Pressure in system (worst case)

Manifolds optimization, Joël Grognuz CO 2 system simulation result TRT pressure oscillations increase with valve response- time and flow/pressure: (qualitative results)

Manifolds optimization, Joël Grognuz TRT wheels passive protection Safety valve: Safety valve:  Valves work for  p>10mbar  Placing valves upstream and downstream is not totally safe! Rupture disc: Rupture disc:  Space limitation problem  Accessibility if need to be changed!? 5cm

Manifolds optimization, Joël Grognuz Further work Resurrect the cooling system simulation Resurrect the cooling system simulation Define and order components (C-wheel!?, pipe routes) Define and order components (C-wheel!?, pipe routes) Passive safety device on wheels!? Passive safety device on wheels!? Find a location to build prototype #2 Find a location to build prototype #2 Build it! Build it!