1. CALICE Collaboration Meeting at UT Arlington
WP14.5 – Mechanical & Thermal tools for Innovative Calorimeters
Cooling system and thermal studies for SiW Ecal
CALICE Collaboration Meeting at UT Arlington
14/09/2016
Denis Grondin / Julien Giraud [LPSC]
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No

2. WP Task 2
Infrastructure to evaluate thermal properties of calorimeter structures (DESY & LPSC)
2.1 Cooling system to test thermal modelling of large CF (carbon fiber) structures (LPSC)
2.2 Cooling system for low power calorimeter readout electronics (DESY)
Cooling studies : From detector to cooling station
Cooling System and constraints
Specification of local Cooling System
Design of Local heat exchangers
Hydraulic and thermal considerations
Thermal Analysis of SLAB/Cassettes and modules
Tests and simulation on local detector
GLOBAL COOLING System modelling
Hypothesis for calculation
Cooling Plant Design
THE leakless OPERATION MODE
Develop and test a Global cooling True scale leak less loop for ECAL (13m,10m,9m)

3. Cooling System and constraints
The development of a cooling system for low power calorimeter readout electronics is based on design close to those of the ILD innovative ILC
Cooling needs for electronics and constraints :
Leakless cooling system
Cooling front–end
Low water speed
Low temperature gradient
Risk of spray limited
• Mechanical constraints due to electronic design (geometry of DIF card);
• Space available: heat sources location;
• Fastening system for cooling allowing fast connection/disconnection;
• Heat power to dissipate, including (chips + DIF FPGA + interface components);
• Hydraulic network, number of circuits;
• Unfavourable environment (high radiation levels, magnetism, particles jets…) etc.…
ECAL
HCAL
Due to leakless system, the pipes come from the bottom, implying significant congestion
ECAL: (CFRP+W structures + Silicon detectors)
Maintaining temperature close to ambient
Gradient accepted in SLAB detector 20°c (then, 20°c< T < 40°c maximum)
Wide surface for exchange / low surfacic power (4.6 Kw for the full ECAL detector )
Precision of cooling regulation +/- 2.5°c acceptable
Service space between cooling and HCAL >1cm for cabling: DAQ + HV + GND
HCAL: (Stainless Steel absorber stack structures +…)
Goal for cooling regulation similar to ECAL
No active cooling of slabs (provided by steel absorber)
More space for cooling of interfaced (gap between barrel and endcap, distance between layers ~2.7 cm)
Cooling station on going

4. Specification of local Cooling System
. The cooling technology is active, using fluid circulation
design and construction of the heat exchanger
ECAL:
the connection of pipes to each slab, it is done by the way of cold copper blocs, brazed on pipes, inserted between the 2 copper sheets of the slab, in the free space let between the 2 DIF cards. Then, there is one cooling water exchanger in front of each column.
Heat shield: µm (copper)
Copper drain extremities for one column as tested on EUDET module, with copper blocs to screw on heat exchanger
EUDET adaptation of Water heat exchanger
Copper plate / heat exchanger link
(Left) Design of connection of heat exchangers with one copper drain extremity (Middle) heat exchanger for 15 (x2) connections with Inlet and Outlet pipes on the upper side (Right) localisation of cooling system on one module
Design of connection of heat exchangers- Schematic view of a slab with 2 copper drains
Cooling station on going

5. Thermal Analysis of slab/cassette and module
ECAL:
Ex. of numerical simulation of heat dissipation in one layer with a FPGA power of 2W; with a exchange coefficient in the pipe with fluid at 20°c (h = 3445 W/m².K)
Boundary conditions:
• Load case (for 1 half slab = 1 side):
Channel heat flux : 25 μW
Number of channel / chip : 64
Number of chip / wafer : 4
Number of wafer on ½ SLAB : 32
Total wafer power = W
FPGA power = 2W (on DIF surface)
Slab medium length / barrel: 1,55 m
Copper plate : 400 μm thick;
• Limit Conditions :
Temperature = 20°C,
Copper : λ = 400 W/m/K
Thermal gradient complient in SLAB detectors and modules

6. Hydraulic and thermal considerations
The specification of the global cooling system will have to take into account:
- To guaranty a leak less zone by line, covering all detectors (2m< <8m);
- Sufficient flow;
- General operation;
- Isolating a line in case of leakage;
Commissioning procedure;
Lines setting.
Establishment of the system operating model
ECAL:
Numbers (RECAL = 1,8m, Zendcaps=2,35m)
40 Barrel modules (all identical)
24 Endcaps modules (3 types) with ≠ shapes
9600 Slabs (6000 (B) (EC) many ≠ lengths
~ ASUs / 300K Wafers / 1,2M VFE chips / 77M channels: 4.6 Kw
ECAL: relative pressure variation / height
Cooling station on going
ECAL: specific distribution network for leakless cooling

7. Global Cooling System Modelling
ECAL:
Global design
Barrel : number of pipe 80
End cap : number of pipe 48
Total number of pipe
128
Inner pipe diameter (mm) depends on the sector detector position
10 / 13
Maximum power per column (w)
150
Flow rate / column (l/min)
0.8
Total flow rate (l/min)
243.2
ECAL: calculation of flow rates in the network
Length of cooling lines for ECAL deducted from calculation
Cooling lines distribution per module ( 1column represented)
Caracteristics of cooling fluid :
Density : 1000 Kg/m3
Calorific power : 4200 J/Kg/°K
Conductivity : W/m/°k
Kinematic viscosity : ν = 10-6 m2/s
The diameters of the pipes are determined to obtain a fluid flow rate of less than 2 m / s and a water temperature rising T = 2 ° C

8. ECAL: Thermal modelling & local heat exchangers
ECAL: Tests and simulations on local detector
Thermal modelling & local heat exchangers
The deliverable will be based on ECAL design for the ILC Electromagnetic Calorimeter (CF+W structures + silicon detectors)
Tests and simulation on detector (EUDET module)
Prototype of SLAB with 4 ASU connected [LLR-LPNHE-LAL]
Power per SLAB: From current design of CALICE
Final goal with power pulsing 1/100 s
Ecal detector : 4.5 Kw
ECAL Module
Dummy slab specification for tests
Heat exchanger connection
0,3W Front Heater
3 x Thermocouple P class 1 (±0.5°C de -40 à +125°C)
Inside 4 SLAB
Heater wire W / surface 1.5 m x 0.18 m
Assembly of the slabs of central column
Dummy SLAB with heater to simulate power dissipation :
ASU => 0.5 W to 1 W per ½ SLAB
Front => 0.3 W to 3 W per ½ SLAB
Cooling effect.
Realization of 15 SLAB (Aluminum / copper / Plastic)
Thermal properties of tungsten and carbon fibre based absorber elements drive the cooling concepts of ultra-granular SiW ECAL. It will feature 10 to 15 layers of double sided integrated detector elements (SLABs) in a Tunsgten-Carbon Fiber (W-CF) support

9. EUDET module (carbon structure) equipped with it’s heat exchanger
ECAL: tests and simulation on detector (EUDET module)
Adaptation of Water heat exchanger
Connection on slab
Slab assembly
EUDET module (carbon structure) equipped with it’s heat exchanger
15 slab in EUDET module
Heat exchanger assembly
Dummy slab detector under construction for thermal tests on EUDET 15 slabs for 1 column
Cooling tests: From detector to cooling station
Realistic interface electronics for slabs
Dummy DIF with representative power and localisation of hot spots
Geometry, power distribution and representative materials
Local Heat exchanger with 15 connections
Full module equipped / conductive materials
First tests results in line with simulations

10. ECAL: tests and simulation on detector (EUDET module)
Demonstration and performance of Thermal model
Thickness : 1 mm
Gradient accepted in detector elements: 20°c -> T° rising in slab: ~up to 7°C
20°c < T < 40°c > maximum: 24°C
With Insulation
Requirements for 15W nominal
For ~30W tested with cooling
Without external Insulation
Test 9
Test 10
Cooling OFF
Cooling ON
Test 9 :
No cooling / Power ASU : 32 W/column => maximum temperature : 31°c
Test 10 :
Cooling / ASU power : 31 W/column => maximum temperature : 24 °c
Important thermal inertia => 4 days minimum of stabilization

11. The Leak less Mode ΔP return ΔP supply ΔPdetector Ppump Ptank h
Principle of leak less:
A big siphon !
Pressure distribution as a function of height, depends on the pressure drop and altitude
ΔP return
ΔP supply
ΔPdetector
Ppump
Ptank h
Pin < Patm
Pout
Should a leak occur inside the detector or anywhere downstream to the cooling plant, no water will be spilled out. Instead, air will infiltrate into the system and be flushed down the return pipe and accumulate inside the reservoir.
It works only if Pin < Patm
Not all the loop is under-pressure!!!
ΔPdetector vs flow must be known
ΔPreturn should be calculated
Pressure drops inside the detector and in the return lines are carefully minimized :
Pout = ∆Preturn + Ptank -ρgh > ρU
Jose Direito TS/CV/DC,
Where ½ ρU 2 (U, flow speed; ρ density) is the dynamic pressure at the detector inlet

12. The Leak less Mode: towards a large loop
Towards Deliverables 14.8
demonstration and performance of a large leak-less cooling-loop on 3 levels (13m-10m- 9m)
Rough estimate on fluid circulation:
Global flow rate : 250 l/min
Variation of fluid temperature : in-out => 3°c
Fluid speed < 2 m/s
Maximal pressure drop : 1.2 bar
Flow rate 0,8 l/min (column)
Total heat to be removed: # 4.6 kW
Total Volume of water in installation ≈ 200L
cooling station
13m High Line
9 m Low Line
10 m Medium Line
2,5 m
5,1 m
4,5 m
Cooling Station
LPSC cooling test area with a drop of 13 m
Cooling station on going
Design of one leakless loop for next tests