DES DHE Electronics Chassis --- Vaidas Simaitis 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

DES DHE Electronics Chassis --- Vaidas Simaitis 2 6-SLOT + 4-SLOT CHASSIS

DES DHE Electronics Chassis --- Vaidas Simaitis 3 FAN MANIFOLDS ADDED

DES DHE Electronics Chassis --- Vaidas Simaitis 4 FANS ADDED

DES DHE Electronics Chassis --- Vaidas Simaitis 5 COOLING MANIFOLDS ADDED

DES DHE Electronics Chassis --- Vaidas Simaitis 6 HEAD EXCHANGERS ADDED

DES DHE Electronics Chassis --- Vaidas Simaitis 7 MAIN MANIFOLDS ADDED WITH HEAT SINK FOR THERMOELECTRIC COOLER

DES DHE Electronics Chassis --- Vaidas Simaitis 8 POWER SUPPLIES ADDED

DES DHE Electronics Chassis --- Vaidas Simaitis 9 POWER SUPPLY MANIFOLDS ADDED

DES DHE Electronics Chassis --- Vaidas Simaitis 10 DELRIN MOUNTING INSULATORS

DES DHE Electronics Chassis --- Vaidas Simaitis 11 MOUNTED TO INNER CYLINDER (1/4 SHOWN)

DES DHE Electronics Chassis --- Vaidas Simaitis 12 CONNECTOR BULKHEAD

DES DHE Electronics Chassis --- Vaidas Simaitis 13 WITH MODULE IN GREEN

DES DHE Electronics Chassis --- Vaidas Simaitis 14 Z-AXIS VIEW WITH R=52” ID CLEARANCE CYLINDER

DES DHE Electronics Chassis --- Vaidas Simaitis 15 WORST-CASE MODULE EXTRACTION

DES DHE Electronics Chassis --- Vaidas Simaitis 16 WHOLE ASSEMBLY CAN BE TILTED AT EITHER END FOR MODULE EXTRACTION

DES DHE Electronics Chassis --- Vaidas Simaitis 17 Z-AXIS VIEW WITH HEAT SHIELDS ADDED

DES DHE Electronics Chassis --- Vaidas Simaitis 18 BOTTOM PERSPECTIVE OF ENTIRE ASSEMBLY

DES DHE Electronics Chassis --- Vaidas Simaitis 19 TOP PERSPECTIVE OF ENTIRE ASSEMBLY

DES DHE Electronics Chassis --- Vaidas Simaitis ” 22” 12” HEAT SHIELD SIZE

DES DHE Electronics Chassis --- Vaidas Simaitis 21 COOLING SYSTEM SIZE 14” 12” 21.5”

DES DHE Electronics Chassis --- Vaidas Simaitis 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°C then ΔT = 50°C Q = heat flow rate = l A ΔT / L= 0.03 x 1 x 50 x 16 = 24 Watts

DES DHE Electronics Chassis --- Vaidas Simaitis 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

DES DHE Electronics Chassis --- Vaidas Simaitis 24 THERMOELECTRIC COOLER 2 T-ambient is in fact the temperature of the electronics, which is assumed to be 30°C The heat sink temperature rise can be 1 st 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?)

DES DHE Electronics Chassis --- Vaidas Simaitis 25 THERMOELECTRIC COOLER 3 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 W x 0.1 C/W = 41°C which is close to the assumed value

DES DHE Electronics Chassis --- Vaidas Simaitis 26 THERMOELECTRIC COOLER 4 Single stage TE’s are most efficient at a ΔT = 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 specifications and pricing of these 2-stage TE’s Yes, this is still all theoretical!

DES DHE Electronics Chassis --- Vaidas Simaitis 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

DES DHE Electronics Chassis --- Vaidas Simaitis 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 M spec is 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”)

DES DHE Electronics Chassis --- Vaidas Simaitis 29 ΔT OF COOLING WATER 1 gallon of water weighs 3784 grams ½ gallon/min = 1892 grams/min 1W = 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 ?

DES DHE Electronics Chassis --- Vaidas Simaitis 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