EN Cooling and Ventilation Activity report on NA62-GTK project

European Organization for Nuclear Research - Organisation européenne pour la recherche nucléaire

1GTK meeting Mainz 6th September 2011

EN Cooling and VentilationActivity report on NA62-GTK project

Michele Battistin, Enrico Da Riva, Vinod Rao, P. ValenteCERN Engineering DepartmentCooling and Ventilation Group

NA62-GTK Meeting, Mainz, 6th September 2011

M. Battistin, E. Da Riva, V. Rao, P. Valente



Agenda

• CFD simulation on Microchannel solution for GTK

• Cooling unit engineering specification




GTK Microchannel Cooling- CFD Analysis for Hydraulic Design -



Summary

4GTK meeting Mainz 6th September 2011 M. Battistin, E. Da Riva, V. Rao, P. Valente

A) Silicon Microchannel C6F14 Heat Exchanger Present prototype (Design-0) Analytical model for pressure drop CFD model and validation against experimental data Performance of present prototype (Design-0) Performance of double inlet/outlet (Design-1)

B) General Design Guidelines Influence of channel geometry Possible alternative refrigerants


Summary





Present prototype (Design-0)


Design-0 geometry

• Refrigerant C6F14, temperature = -25°C• Max inlet/outlet temperature rise = 5 K• Heat load = 48 W• cp = 975 J kg-1 K-1

Mass flow rate 9.8 g/s

A first prototype has been manufactured and tested by CERN PH/DT

The dominating thermal constraint is considered the in/out refrigerant temperature rise and not the HTC achieved inside the microchannels

Design operating conditions


Present prototype (Design-0)


Velocity in manifolds and microchannels

Design power

Mass Flow Rate

um

(manifold)Re

much

(channel)Re

ch

48 W 9.8 g/s 11.45 m/s 6882 1.81m/s 223

The flow is laminar in the microchannels and turbulent in the manifold Too high manifold velocity high pressure drop + maldistribution


Summary





Analytical model


Most of the pressure drop is due to the manifold

0.00 2.00 4.00 6.00 8.00 10.00 12.000

2

4

6

8

10

12

14

Pressure drop variation with mass flow rate @ -25°C for present Prototype (Design-0)

manifold Pressure dropchannel Pressure droptotal pressure drop

mass flow(g/sec)

pres

sure

dro

p(ba

rs)


Summary





CFD model and validation


Mesh data ->No. of cells : 8.2 M Hexahedra: 8.1 M polyhedra: 0.1M

->Mesh non-orthogonality Max: 39.9 Average: 3.6

The CFD model is able to predict experimental the data for the whole range of mass flow rates tested

0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.0080

1

2

3

4

5

6

Pressure drop comparison @ 15°C for Design-0

Exp.CFD

mass flow rate [kg/s]

pres

sure

dro

p [b

ar]


Summary





Performance of Design-0


Pressure drop

Flow distribution

The refrigerant pressure drop predicted by the CFD model at design working conditions is 12.2 bar

This value could give rise to mechanical resistance problems

The Average mass flow rate in each channel is 0.03 g/sec

The distribution is not optimal The channels close to outlet are fed

with almost double the mass flow rate as compared to the ones close to the inlet

The temperature rise for the channels close to the inlet is expected to be higher then 5 K


Summary






As a first step to reduce the pressure drop in the manifold without changing the Design-0 main geometry , A dual inlet/outlet solution is proposed

Design-0 sketch Design-1 sketch

Flow distribution & Pressure drop

Geometry

Δp = 12.2 bar Δp = 5.7 bar

Design-1 (double inlet/outlet)


Summary


A) Silicon Microchannel C6F14 Heat Exchanger

Present prototype (Design-0) Analytical model for pressure drop CFD model and validation against experimental data Performance of present prototype (Design-0) Performance of double inlet/outlet (Design-1)



Influence of channel geometry


The double inlet/outlet configuration is considered.The width of the silicon wall between the channels is considered fixed

(100 μm). The mechanical resistance of high aspect-ratio channel has to be

checked. According to the present results, the material budget can be reduced

without increasing the global pressure drop.



Pressure Drop with Perfluorohexane with dual Inlet-Outlet@-25°C with 9.84g/s for 48 Watts | 100 microns wall

Channel width

No . Of channel

Channel depth ->

[Microns]50 60 70 80 90 100

500.0 50 8.3 5.6 4.3 3.5 3.0 2.7

400.0 60 8.7 5.9 4.4 3.6 3.1 2.8

328.6 70 9.1 6.2 4.6 3.8 3.2 2.9

275.0 80 9.6 6.5 4.8 3.9 3.3 3.0

233.3 90 10.2 6.8 5.1 4.1 3.5 3.1

200.0 100 10.8 7.3 5.4 4.3 3.7 3.2

172.7 110 11.6 7.8 5.8 4.6 3.9 3.4

150.0 120 12.5 8.4 6.2 4.9 4.2 3.6

130.8 130 13.6 9.1 6.7 5.4 4.5 3.9

114.3 140 14.9 10.0 7.4 5.9 5.0 4.3

100.0 150 16.6 11.2 8.3 6.6 5.6 4.8

9.7

21.1

3.0

5.7

6.1

CFD Results in Red


Summary


A) Silicon Microchannel C6F14 Heat Exchanger

Present prototype (Design-0) Analytical model for pressure drop CFD model and validation against experimental data Performance of present prototype (Design-0) Performance of double inlet/outlet (Design-1)



Possible alternative refrigerants


For HTC calculation, Nusselt number is taken as constant (=3.2). C6F14 is the only dielectric fluid considered in the table. High cp allows to reduce mass flow rate and pressure drop. Water displays optimal properties but can be used only above 0°C. Liquid CO2 displays good properties but the saturation pressure is extremely

high even at low temperature. Ammonia displays optimal thermodynamic properties and also a very low

saturation temperature .

Fluid Temperature [°C] Pressure [bar] CP [J/Kg-k] η [cSt] Density[Kg/m3]

HTC [Laminar flow with Dh=.1mm]

C6F14 -25 1 975 .81 1805.25 2008

Water 25 1 4181 .892 997 19424

Glycol[45%] -25 1 3211 24 1080.6

CO2 -25 18 2111 .143 1054.7 4480

Ammonia -45 .9 4387.1 .43 696.18 22560


Pressure Drop with dual Inlet-Outlet@25°C with 2.3g/s for 48 Watts | 100 microns wall


Fluid : Water

Properties @ 25°C , 1 bar:

Cp = 4181 J/kg-K

kinematic viscosity (η) = 0.892 cSt

Density = 997 kg/m3

Water could be an optimal solution for operating conditions above 0°C

A cooling system operating below atmospheric pressure could be designed in order to avoid leakages problems.

Channel width

No. of channel

Channel depth ->

[microns]50 60 70 80 90 100

500.0 50 1.38 0.90 0.65 0.51 0.42 0.36

400.0 60 1.49 0.97 0.70 0.55 0.45 0.38

328.6 70 1.61 1.05 0.76 0.59 0.48 0.41

275.0 80 1.76 1.15 0.83 0.64 0.52 0.44

233.3 90 1.92 1.26 0.91 0.70 0.57 0.48

200.0 100 2.12 1.39 1.01 0.78 0.63 0.53

172.7 110 2.35 1.55 1.12 0.86 0.70 0.59

150.0 120 2.63 1.74 1.26 0.97 0.79 0.66

130.8 130 2.97 1.98 1.43 1.11 0.90 0.75

114.3 140 3.38 2.27 1.65 1.28 1.03 0.86

100.0 150 3.90 2.63 1.92 1.49 1.21 1.01


Pressure Drop with dual Inlet-Outlet@-25°C with 3g/s for 48 Watts | 100 microns wall


Fluid : Glycol 45% solution

Properties @ -25°C :

Cp = 3211 J/kg-K

kinematic viscosity (η) = 24 cSt

Density =1080.6 kg/m3

Freezing Point = -30.5°C

Glycol cannot be used to employ water in microchannels below 0°C, because the viscosity is extremely high.

Channel width

No. of channel

Channel depth ->

[microns]50 60 70 80 90 100

500.0 50 42.59 25.55 16.67 11.56 8.40 6.34

400.0 60 46.40 28.06 18.45 12.89 9.43 7.16

328.6 70 50.78 30.96 20.51 14.44 10.65 8.14

275.0 80 55.86 34.35 22.94 16.27 12.08 9.30

233.3 90 61.78 38.32 25.81 18.45 13.80 10.69

200.0 100 68.74 43.03 29.22 21.05 15.86 12.37

172.7 110 77.00 48.65 33.33 24.20 18.37 14.43

150.0 120 86.90 55.45 38.32 28.06 21.46 16.97

130.8 130 98.90 63.74 44.46 32.83 25.29 20.15

114.3 140 113.64 74.01 52.11 38.80 30.13 24.17

100.0 150 131.98 86.90 61.78 46.40 36.31 29.33


Pressure Drop with dual Inlet-Outlet@-25°C and 18 bars with 4.5g/s for 48 Watts | 100 microns

wall


Fluid : Carbon Dioxide

Properties @ -25°C, 18 bar

Cp =2111 J/kg-K


Density =1054.7 kg/m3

The pressure drop with liquid CO2 is extremely low, but this is useless since the saturation pressure of CO2 is high (16.8 bar @ -25°C).

Channel width

No. of channel

Channel depth ->

[microns]50 60 70 80 90 100

500.0 50 1.05 0.90 0.82 0.77 0.74 0.73

400.0 60 1.08 0.92 0.83 0.79 0.75 0.73

328.6 70 1.12 0.95 0.85 0.80 0.77 0.74

275.0 80 1.17 0.98 0.87 0.82 0.78 0.75

233.3 90 1.22 1.01 0.90 0.83 0.79 0.77

200.0 100 1.28 1.05 0.93 0.86 0.81 0.78

172.7 110 1.36 1.10 0.97 0.89 0.83 0.80

150.0 120 1.45 1.16 1.01 0.92 0.86 0.82

130.8 130 1.55 1.24 1.07 0.96 0.90 0.85

114.3 140 1.68 1.33 1.14 1.02 0.94 0.89

100.0 150 1.85 1.45 1.22 1.08 0.99 0.93


Pressure Drop with dual Inlet-Outlet@-45°C with 2.19g/s for 48 Watts | 100 microns wall


Fluid: Ammonia

Properties @ -45°C, 0.9 bar

Cp =4387.1 J/kg-K


Density = 696.18 kg/m3

Ammonia could be an optimal solution for operating conditions below 0°C

A cooling system operating below -35°C and below atmospheric pressure could be designed in order to avoid leakages problems.

Channel width

No. of channel

Channel depth ->

[microns]50 60 70 80 90 100

500.0 50 0.80 0.57 0.46 0.39 0.35 0.32

400.0 60 0.85 0.61 0.48 0.41 0.36 0.33

328.6 70 0.91 0.65 0.51 0.43 0.38 0.35

275.0 80 0.97 0.69 0.54 0.45 0.40 0.36

233.3 90 1.05 0.74 0.58 0.48 0.42 0.38

200.0 100 1.14 0.80 0.62 0.52 0.45 0.40

172.7 110 1.25 0.88 0.68 0.56 0.48 0.43

150.0 120 1.38 0.97 0.74 0.61 0.52 0.46

130.8 130 1.54 1.08 0.82 0.67 0.57 0.50

114.3 140 1.73 1.21 0.92 0.75 0.63 0.56

100.0 150 1.97 1.38 1.05 0.85 0.72 0.62


Conclusions


The velocity in the manifold of the present prototype is too high, therefore the total pressure drop is high (i.e. ~12 bar) and the flow distribution is not uniform.

Before improving the channels design, the manifold design must be fixed.

Adopting double inlets/outlets allow to half the pressured drop and improve the flow distribution without changing the overall manifold geometry.

Neglecting possible mechanical resistance problems, the material budget could be further decreased by adopting high aspect ratio channels.

From the hydraulic point of view, liquid ammonia at around -40°C would allow to operate a microchannel heat exchanger below the atmospheric pressure thus avoiding mechanical resistance and leakages problems.


NA62 Gigatracker cooling systemengineering specification

Piero Valente, Michele Battistin

26


Thermodynamic requirements – Fluid: C6F14

– Total required cooling power : 300 W (spare power factor =2)– Number of distribution loops = 3– Supply temperature = -25C– Loop temperature stability = ± 0.5K– Temperature difference between loops = 2 K– Design pressure: 16 bar– Pressure drop : still to be defined by GTK collaboration

27


User requirements – VDF pump power supply for smooth start-up sequence– PVSS-UNICOSS control and supervision– Control cupboards installed in the remote protected area (200 m

distance)– Automatic control of loop flowrate and temperature– Remote control of delivery temperature and flow rate for each loop– Interlocks for high delivery pressure– Fully redundant operation: chiller, heat exchanger and circulation pump– Oil free cooling station– Pneumatically actuated valves– Cooling station to be tested in laboratory - Meyrin site

28


Proposed solution– HCFC refrigerant primary chiller (-40 °C)

– Chiller overall cooling power: 1.5 kW (including heat losses)

– C6F14 total mass flow ≈ 0.333 kg/s (pre-design figure)

– Three bigger pipelines (OD 12) carrying ≈ 0.100 kg/s C6F14 flow each

– Three smaller pipelines (OD6) carrying 0.011 kg/s C6F14 flow to each detector

– A heat exchanger for each line, located ≈1 meter from the detector, will guarantee operating temperature setting of -25C

29


Proposed solution : P&I

30

Main pipelines OD 12

Detector pipelines OD 6

Heat exchangers


31

Planning– Engineering specification approval …….. end September 2011 (EN-CV; NA62)

– System design ……………………………………. October-November 2011 (EN-CV)

– Procurement ……………………………………… December 2011-March 2012 (EN-CV;FP)

– Installation ………………………………………… April-June 2012(EN-CV; Contractor)

– Tests…………………………………………………… July-September 2012(EN-CV;Contractor)

– Commissioning…………………………………… October 2012 (EN-CV; Contractor)


32

Budget

– Mechanical components………………………..110 kCHF

– Electrical and control equipments ….……..30 kCHF

– Manpower………………………………….….……..40 kCHF

Total 180 kCHF


Alternative solutions?CERN TOTEM Cooling system

Michele Battistin

33


TOTEM Roman Pots C3F8 Evaporative cooling system

Eng Spec EDMS 778214 v1

POTS STATIONS LOCATION

DESIGN PARAMETERS

XRP1 XRP3XRP3

XRP1

Main station


Roman Pot cooling

Evaporative system @ C3F8Lamination phase between points A and B

A

B

C

OPTION 1 - Capillary

lamination into a capillary located insidethe Pot

+ no need of insulation and heatintake on the supply line, horizontalflexibility

- to be individually tested, timeconsuming, behaviour off design to bestudied

OPTION 2 - Manual valve

lamination into a manually adjustablevalve located outside the Pots, as near aspossible

+ commercial component, time andcost effective, reliability, flexibility

- need of insulation to avoidcondensation, heat intake fromenvironment

A BC

Compressor design[ data from HAUG, supplier of dry compressors succesfully

tested for SR1 and Atlas evaporative machine]

Nominal flow rate 2 g/s per circuit48 g/s total20.3 Nm3/h

Option 1

WTEGX 80/603 cylinders2 stages

0.8-10 bara @ 13 Nm3/h1.0-10 bara @ 18 Nm3/h

~30 kCHF

Option 2

VTOGX 120/602 cylinders2 stages

0.8-10 bara @ 20 Nm3/h1.0-10 bara @ 30 Nm3/h

~50 kCHF


TOTEM RP cooling

C3F8 main working points


TOTEM RP cooling

System schematicPI

01

PT

01

PI

02

PT

02

PI

03

PT

03

PI

04

PT

04

PI

12

PT

09

XRP1 - UJ57

XRP3 - UJ57

XRP1 - UJ53

XRP3 - UJ53

NC NC

NC NC

TT

01

Mixed waternetwork

C3F8 Storagetank

TT

14

PI

11

PT

07

Capillary 01

Capillary 02

RP coil 01

RP coil 02

Capillary 03

Capillary 04

RP coil 03

RP coil 04

Capillary 05

Capillary 06

RP coil 05

RP coil 06

Internal of the Roman Pots

Limit of TS/CV/DC supply

Demineralisedwater network

DN50

DN10

DN10DN50

PT

08

DN32

DN32

DN25

TT

13

FT

01

TT

10

TT

02

TT

03

TT

04

PT

05PI

07

PI

06

PI

05

TT

07

TT

06

TT

09

PT

06PI

10

PI

09

PI

08

WCS

01 TT

15

DN25

FT

02

TT

12

TT

11

A

BC

D

F

DUMMYLOAD

PI

13

TT

16

Back pressureregulators

60 mbar @ 10 g/s

Pressure regulators100 mbar @ 10 g/sPT

10

PT

11

PT

12

PT

13

NO

NO

NO

NO

NC

NC

NC

NC

TT

05

TT

08

PID reg

PID reg

PID reg

G

E

DonaldsonUltrafilters

Flexibleconnection

DN25

DN25

DN25

DN15

DN15

NC

DN15

DN10

Copper return

liquid line 26/28

Copper supply

gas line 12/14

DN10

G


Could it be the solution for GTK?

• The solution has already been used for TOTEM electronics (25 W; 2 g/s; C3F8)

• Low operation temperature easily achivable (-43°C during Totem tests)

• Low opeartion pressure on the detector (1 bara; -37°C)

• The system is running since 2007 with high reliability

• Tranfer lines operates at ambient temperature: can be very long (300 m for Totem): the cooling station ca be in an accessible area (no operation in the protected zone)

• Temperature stability and uniformity is granted by the evaporation temperature

• Known thecnology both on detector structure than on the cooling system.

EN Cooling and Ventilation Activity report on NA62-GTK project

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