First Look at VXD Gas-Cooling

1. First Look at VXD Gas-Cooling Arrangement of the layers Layer Radius # of Width of Length of Ladders Ladder Ladder inner wall 14 mm - - - 1 15 mm 8 13 mm 100 mm 2 26 mm 8 22 mm 250 mm 3 37 mm 12 22 mm 250 mm 4 48 mm 16 22 mm 250 mm 5 60 mm 20 22 mm 250 mm outer wall 72 mm - - - • Assumptions and requirements : • A cylinder of ladders forms an almost closed surface. • No flow of gas through a layer of ladders, no radial • pressure differences allowed. • Flow conditions should be the same for each ladder. • One inlet hole for each ladder. • Diameter of holes for different layers has to • matched to above requirements. Turbulant flow through a pipe : ; F= cross section of hole v= velocity gas r= density of gas Arrangement of holes Layer Radius Diameter # of Holes 1 20.5 mm 6.74 mm 8 2 31.5 mm 8.00 mm 8 3 42.5 mm 7.66 mm 12 4 54.0 mm 7.78 mm 16 5 65.5 mm 7.72 mm 20 Page 1

2. First Look at VXD Gas-Cooling Din = DVXD= Dout pVXD VXD pout pin DVXD= 57.25 D(r=4mm) pVXD DVXD= 0.52 kg/s vVXD= 27.6 m/s N2 at 0o C Page 2

3. First Look at VXD Gas-Cooling Removal of heat : l = heat transfer coefficient Nu = Nusselt number L = length of a ladder ; The Nusselt number is a function of the Reynold number Re : n =kinematic viskosity Temperature increase of gas : Choose DTladder-gas = 10 K Page 3