From: SMTP%"derylo@fnal.gov" 29-JAN-2000 19:50:22.56 To: BLUSK CC: Subj: Temp Estimates Date: Sat, 29 Jan 2000 19:50:10 -0600 From: Greg Derylo Subject: Temp Estimates To: blusk@fnal.gov Cc: brenna@fnal.gov Message-id: MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII Steve -- Here is an estimate for the pigtail temps. I don't know what these cables look like, so my surface area (0.06 m^2) may be off. If you let me know more detail about the configuration, I may refine the model. Also, since the junction-card-end boundary condition is difficult to evaluate, I assumed two different types of conditions: 1) The junction card is at a fixed temperature, which I vary. This allows some heat from the cable to flow into the junction card (or, if I assume it is hot enough, to flow from the card into the pigtail). 2) The junction-card-end of the tail is insulated and therefore no heat is exchanged here. I make the following basic assumptions: Q = 1 W, A_copper = 0.08 cm^2, T_air = 20C, T_portcard = 10C and yield the following maximum temperature results: T_max (degC) h ============================================ (W/m^2-K) T_jc = 20C 30C 40C 50C Insulated ========= =========== ===== ===== ===== ========= .000001 86 92 97 103 294 .00001 85 91 96 101 278 .0001 77 81 86 90 181 .001 44 46 48 51 52 .01 23 30 40 50 23 .1 20 " " " 20 1 " " " " " 5 " " " " " 10 " " " " " 100 " " " " " The temps look good for convection coefficients down to several orders of magnitude less than values typical of natural convection under good conditions (about 5 W/m^2-K). I think this is pretty promising. Greg