Date: Mon, 12 Jun 2006 13:14:05 -0600 From: Bill Miller To: Carl Haber , Gil Subject: 8mm tube Parts/Attachments: 1 OK ~14 lines Text (charset: ISO-8859-1) 2 Shown ~30 lines Text (charset: ISO-8859-1) ---------------------------------------- I calculated the heat transfer for the larger tube. I get for the 108W heat load about a 3 to 4C temperature drop on the inside of the tube. You may recall I was using 3000W/m2K for the film coefficient, the same as the small diameter tube in the pixel detector. for this tube I get a film coefficient on the order of 660 to 770 depending on flow conditions. The velocities are very low in the tube. The lower coefficient creates a 3-4 C temperature whereas before we had less than a degree. My new estimate for this tube is about -20C on the wafer instead of -23C before for -25C in. Bill W. O. Miller 505-298-7633 626-369-1273 (Allcomp) Date: Mon, 12 Jun 2006 17:50:24 -0600 From: Bill Miller To: Carl Haber , Gil Subject: stiffness for 8mm Parts/Attachments: 1 OK ~14 lines Text (charset: ISO-8859-1) 2 Shown ~33 lines Text (charset: ISO-8859-1) ---------------------------------------- Compressing the tube to 7.33mm (separation between facings) for a stave of 0.975m length would have an estimated total deflection of 24microns. This is both bending and shear deflection. For shear modulus, I used the same value that I retrieved from the FEA of the Al tube and the foam core. For that solution the analytic solution was 43microns for a 4.6mm core separation. The FEA solution was 54microns. The short of it is that the larger tube should decrease the sag noticeably. This is a quick solution but I wanted to let you know what the cooling and stiffness implications were regarding the change to a larger tube. Bill W. O. Miller 505-298-7633 626-369-1273 (Allcomp) Date: Tue, 13 Jun 2006 21:05:30 -0600 From: Bill Miller To: Carl Haber , Gil Subject: Error in Draft Parts/Attachments: 1 OK ~14 lines Text (charset: ISO-8859-1) 2 Shown ~29 lines Text (charset: ISO-8859-1) ---------------------------------------- I thought I better check the cooling for the 4.6mm tube versus the 8mm tube, both being slightly flatten. The convection coefficient is higher for the small tube. This was my intuition when I prepared the draft sent earlier. However, the heat flux is higher for the smaller tube (both averaged over the length). The effect is that the temperature drop in the film on the inside of the tube is essentially the same for both tubes. There is no apparent heat transfer penalty for the larger tube as I described in the earlier transmittal. Sorry for the confusion Bill W. O. Miller 505-298-7633 626-369-1273 (Allcomp)