LHCb VELO Meeting

LHCb VELO Cooling System

Bart Verlaat (NIKHEF)25 February 2003

LHCb VELO Cooling System Verification of the current design (As described in LHCb note 2001-0XX/VELO, July 02,2001)

2001 status overview

Primary cooling system (R404A/R507):-Capacity: 2.9 kW@-35’C

Secondary cooling system (R744=CO2):-Pmax: 70 bar-Qdetector: 2.5 kilowatt-CO2 mass flow: 17 g/s-Tevaporation: -30’C – 0’C- Warm transport lines.-Adjustable restriction in liquid transport line.-Fixed restriction before 0.9 mm tube: ca. 10 bar.-Heat exchanger between evaporator in and outlet after 1st restriction.

AF

E

D

C B

H

I

G

bverlaat@nikhef.nl, 29 January 03

Me

ltin

g L

ine

-40

-20

-20

0

t = 0

o C

20

20

40

40

60

60

80

80

10

0

10

0

12

0

12

0

14

0

14

0

16

0

16

0

18

0

20

0

22

0

24

0 oC

26

0

28

0

En

trop

y =

-2

.30

kJ/

kg,o C

s =

-2

.20

-2.1

0 -2.0

0

-1.9

0

-1.8

0

-1.7

0

--1.

60

-1.5

0

-1.4

0

-1.3

0

-1.2

0 -1.1

0

-1.0

0 -.90

-.70

-.80

-.60

-.50

-.40

-.30

-.20

-.10

s = 0

Triple Point (5.18 bar, -56.558 oC)

Su

blim

atio

n L

ine

r = 1

200

r = 1

150

r = 1

100

r = 1

050 r =

1000 r =

900r = 800

Density = 700 kg/m3

r = 600

r= 500

r = 400

r = 300

r = 200 kg/m3

r = 150

Density = 20 kg/m3

1

10

100

1,000

300 400 500 600 700 800 900 1000

Enthalpy, kJ/kg

Pre

ssu

re,

Bar

x=0.1 x=0.2 x=0.3 x=0.4 x=0.5 x=0.6 x=0.7 x=0.8 x=0.9

A

F

E

D C

B

G HI

Secondary cooling system cycle in the P-h diagram (1).

Point P (Bar) T (’C) H (J/g)

A 70 -32.7 431.5

B 70 20 552.2

C 24.3 -13 552.2

D 24.3 -30 436.4

E 14.3 -30 436.4

F 14.3 -30 642.1

G 14.3 -13 757.9

H 14.3 20 790.5

I 14.3 -35 426.5

Mass flow 12.15 g/s

Volume flow 0.66 l/min

Liquid heater 1466 Watt

Gas heater 396 Watt

Total heater power 1862 Watt

Transport line pressure

70 bar

Restrixction pressure drop

10 bar

Detector evaporative temperature

-30’C

Detector power 2500 Watt

Liquid subcooling 5 ‘C

Minimum primary cooling capacity: 4362 Watt@-35’C

Design status 2001

Heat exchanger: HFG=HCD

Gas heater (GH)

Liquid heater (AB)

Detector power (EF)

Pump (IA)

bverlaat@nikhef.nl, 29 January 03

Carbon Dioxide: Pressure - Enthalpy Diagram

Me

ltin

g L

ine

-40

0

t =

0 o C

20

40

40

60

60

80

80

10

0

10

0

12

0

12

0

14

0

14

0

16

0

16

0

18

0

20

0

22

0

24

0 o C

26

0

Triple Point (5.18 bar, -56.558 oC)

Su

blim

atio

n L

ine

r = 150

1

10

100

1,000

300 400 500 600 700 800 900 1000

Enthalpy, kJ/kg

Pre

ssu

re, B

ar

x=0.1 x=0.2 x=0.3 x=0.4 x=0.5 x=0.6 x=0.7 x=0.8 x=0.9

A

F

E

D

C B

G/HI

Modified status:-Heat exchanger before 1st expansion valve-140 bar liquid transport

Secondary cooling system cycle in the P-h diagram (2).

Point P (Bar) T (’C) H (J/g)

A 140 -29.9 437.7

B 140 20 540

C 140 -30 437.6

D 24.3 -29.4 437.6

E 14.3 -30 437.6

F 14.3 -30 688.1

G 14.3 20 790.5

H 14.3 20 790.5

I 14.3 -35 426.5

Mass flow 9.98 g/s

Volume flow 0.54 l/min

Liquid heater 1021 Watt

Gas heater 0 Watt

Total heater power 1021 Watt

Transport line pressure

140 bar

Restrixction pressure drop

10 bar

Detector evaporative temperature

-30’C

Detector power 2500 Watt

Liquid subcooling 5 ‘C

Minimum primary cooling capacity: 3521 Watt@-35’C

Heat exchanger: HFG=HAB

Liquid heater (AB)

Detector power (EF)

Pump (IA)

bverlaat@nikhef.nl, 29 January 03

VELO Cooling overview and optimization • Warm transport has more impact on the design as foreseen, but is possible if:

– The primary cooler capacity is increased.

– The liquid transport pressure is increased (70 bar is in a very critical region)

• The efficiency of the system can be optimized by:– Keeping the secondary refrigerant flow (CO2) to a minimum (See table)

– Moving the heat exchanger in the liquid line from CD to AB

– Increasing the liquid transport pressure (Current pump limit is 140 bar)

• The evaporator flow conditions seem to be in the proper flow regime, but are more critical for dry-out in when the system is optimized. (x=0.83 w.r.t. x=0.68) ( “x” is the vapor quality). Tests have to determine the dry-out limit for the VELO evaporator flow conditions.

• If the heat exchanger stays in place the cold gas can be used to cool additionally heat sources on the VELOI. If not applied the cold gas will be heated electrically to avoid conde4nsation on the vapor line.

bverlaat@nikhef.nl, 29 January 03

Results summary 2001 Original Version 2003 Optimized version

Primary cooler capacitance 4.36 kW @ -35’C 3.52 kW @ -35’C

Pump flow 0.66 l/min 0.54 l/min

Detector vapor quality x (%) 68% 83%

Fluid state in heat exchanger

Inlet Vapor/Liquid Liquid

Outlet Vapor/Gas Vapor/Gas

Silicon Wafers thermal requirements:- Operating temperature range: -10 ‘C/ 0 ‘C LHCb2001-070/VELO- Survival temperature range: xx- Temperature stability: xx- Maximum accepted gradient between sensors: xx- Dissipated heat: 0.03W-0.17W (0.3 W max). LHCb2001-070/VELO

Beetle chip thermal requirements:- Operating temperature range: xx- Survival temperature range: xx- Dissipated heat: 2500 Watt total. LHCb2001-0XX/VELO, July 02,2001

External electronics requirements: - External electronics dissipation: 1500 Watt (MVB)

Other heat sources: - Corrugated foil heat dissipation: 2.2 Watt/Foil (FK)- Any other possible heat source???

Other temperature requirements: - Module base operational temperature: Assembly room temperature (ca. 20’C) (MD)- Corrugated foil: Lower than environment to get tension instead of compression. (HBR)- Any other temperature requirements???

LHCb environment temperature: 20'C?Any large amount of dissipation near the Vertex?

bverlaat@nikhef.nl, 18 February 03

VELO thermal requirements:

Future activities(Very preliminary)

• The shown enthalpy cycles will be verified with a low power test set-up, using the existing AMS-TTCS CO2 system at NIKHEF.

– Enthalpy measurements

– Evaporator pressure drop measurements

– Heat transfer measurements (Dry-out determination)

• Based on the test results a baseline design concept will be chosen.

• A BBM (Bread Board Model) will be built conform this baseline.