DHE Chassis and Cooling

DES DHE Electronics Chassis --- Vaidas Simaitis [email protected]

1

DHE Chassis and Cooling

• DES Mechanical Workshop at FNAL

• November 2, 2005

• Vaidas Simaitis

• High Energy Physics Group

• University of Illinois at Urbana-Champaign


2

6-SLOT + 4-SLOT CHASSIS


3

FAN MANIFOLDS ADDED


4

FANS ADDED


5

COOLING MANIFOLDS ADDED


6

HEAD EXCHANGERS ADDED


7

MAIN MANIFOLDS ADDED WITH HEAT SINK FOR

THERMOELECTRIC COOLER


8

POWER SUPPLIES ADDED


9

POWER SUPPLY MANIFOLDS ADDED


10DELRIN MOUNTING INSULATORS


11

MOUNTED TO INNER CYLINDER (1/4 SHOWN)


12

CONNECTOR BULKHEAD


13

WITH MODULE IN GREEN


14

Z-AXIS VIEW WITH R=52” ID CLEARANCE CYLINDER


15

WORST-CASE MODULE EXTRACTION


16

WHOLE ASSEMBLY CAN BE TILTED AT EITHER END FOR

MODULE EXTRACTION


17

Z-AXIS VIEW WITH HEAT SHIELDS ADDED


18

BOTTOM PERSPECTIVE OF ENTIRE ASSEMBLY


19

TOP PERSPECTIVE OF ENTIRE ASSEMBLY


20

17.5”

22”

12”

HEAT SHIELD SIZE


21

COOLING SYSTEM SIZE14”

12”

21.5”


22

RADIATING SURFACE

• A = 2x(12”x 14”+ 12”x 22.5”+ 14”x 22.5”)= ~1500 in² = ~1 meter²

• L = Insulation thickness = .25” = 1/16 m

• l = thermal conductivity= ~ 0.03 W/mK for air

• If T-ambient= -20°C , T-electronics= 30°Cthen ΔT = 50°C

• Q = heat flow rate = lA ΔT / L= 0.03 x 1 x 50 x 16 = 24 Watts


23

THERMOELECTRIC COOLER 1

• Q-hot = heat released hot side = Q-cold + P-in where Q-cold = heat absorbed at cold

side and P-in = electrical Power input

• T-hot = hot side temperature of thermoelectric = T-ambient + Q-hot x Θ

where Θ = thermal resistance of the hot side heat exchanger

• ΔT = required temperature differential = T-hot – T-cold


24


• T-ambient is in fact the temperature of the electronics, which is assumed to be 30°C

• The heat sink temperature rise can be 1st approximated to be 10°C

• Then T-hot = 40°C

• If T-cold = -20°C then ΔT = 60°C

• Assume Q-cold = 10 W for each heat shield

• Assume Θ = 0.10 C/W (possibly?)


25


• If P-in = 100 W (this is hopefully worst case)

• Q-hot = Q-cold + P-in = 10W+100W = 110W

• T-hot = T-ambient + Q-hot x Θ = 30°C + 110 W x 0.1 C/W = 41°C

which is close to the assumed value


26


• Single stage TE’s are most efficient at aΔT = 40°C ± 10°C

• We probably need a 2-stage TE for handling ΔT of 60°C or more

• We have not yet explored the specificationsand pricing of these 2-stage TE’s

• Yes, this is still all theoretical!


27

TOTAL HEAT LOAD• The estimated average DC power for a dual

backplane is ~350 Watts

• If power supply is 80% efficient, it must be producing another 70 W

• Add 2 TE’s at 110 W each

• Add 2 fans at 30 W each

• TOTAL = 700 W

• Or 350 W for each of 2 heat exchangers


28

HEAT EXCHANGERS• T-electronics assumed = 30°C• If we assume T-liquid = 10°C• ΔT = 20°C• Performance required is 350 W / 20°C

= 17.5 W/C• Lytron M05-050 spec is 20W/C @ ½ gpm

with a liquid pressure drop of ~0.5 psi at an air flow of ~60 cfm with an air pressure drop of 0.2 inches of water

(at 100 cfm, the drop is 0.3”)


29

ΔT OF COOLING WATER

• 1 gallon of water weighs 3784 grams

• ½ gallon/min = 1892 grams/min

• 1W = 14.33 calories/min

• 350W = 5016 cal/min

• ΔT = 5016/1892 cal/g -> 2.65°C

• Can we run the two heat exchangers in each crate assembly in series, with a dt = 5.3°C ?


30

FANS

• Should be routine

• For example: a Comair/Rotron Patriot PT2B3 is rated at 150 cfm at 0.3” drop running at 115 VAC at 60 Hz at 31 W.

• PT2D3 should be 75 cfm at 16 W, running at 1700 rpm instead of 3400 rpm

DHE Chassis and Cooling

Documents