Bart Verlaat 13 October 2010

[email protected]@nikhef.nl

News on the CO2 cooling developments at CERN DT

CMS Tracker Upgrade Cooling and Mechanics meeting

Bart Verlaat

13 October 2010

1

[email protected]

[email protected] Status of the current CO2 systems: Blow system

• Joao’s blow system:– Blow system was upgraded

with a 2nd blow branch to create the ability to have more latent heat or sub cooling.

2

Liquid Vapor

2-phase

Pre

ssur

e

Enthalpy

12

3 4 5

Liquid Vapor

2-phase

Pre

ssur

e

Enthalpy

12

3 4

Internal sub cooling External sub cooling

[email protected] Status of the current CO2 systems: Cryo lab 2PACL

• Operational status:– Operational status discussed in Thorsten’s presentation.

• Some modifications done by Joao:– The system had problems with small flows (Large heat leak & low flows = high temperature

differences or unwanted boiling)– System was modified to run always at high flow, small flows to experiments are obtained by a

metering valve in the experiment feed line.

3

• Dummy heater was placed in a 2nd by-pass.• Metering valves were installed in the by-passes to create more

pump pressure.– The R404a compressor unit works stable under high heat

loads. The dummy heater in the by-pass can now be used to increase the cooling load for a stable chiller operation (=stable evaporator with current accumulator).

– Accumulator was ready but had problems with certification.• End flanges were made from a wrong steel grade: ~303 instead

of 316L. (certificate showed the 316L). Error was found during the final material sample analyses.

• Accumulator is remanufactured. Delay is unknown up to now.

[email protected] New developments in CO2 cooling

• A few new CO2 cooling developments are ongoing in CERN-DT.– Development of a 2 multipurpose CO2

coolers for general use based on the 2PACL principle (LHCb and AMS systems).

• A “portable” air-cooled 100Watt system• A “not so portable” water cooled 1kW system• Operational temperature range of both systems:

-40°C to +25°C evaporative temperature.– Development of new concepts

• Making the system simpler (portable system)• To reduce accumulator volume (important for

large scale systems)– Contribute to concepts for future systems

• CMS pixel / upgrade• Atlas IBL / upgrade (SR1-cooling plant) 4

[email protected] The 1kW “xxxxx” system

• Development of the kW system is in close cooperation with Nikhef.

• Nikhef is developing a CO2 cooler for the XFEL detector at DESY. A common design is made as specs are (almost) identical.

• Concept is to make them from a user stand point as simple as possible. Basic CO2 cooling knowledge required. – 3 user input variables:

• Evaporative temperature• Mass flow• Enthalpy (sub cooling or vapor quality for user)

– 4 operation states: • Connecting experiment• Disconnecting experiment• Cooling experiment • (re) filling CO2

– User interface via integrated touch screen, connection of PVSS is optional but not required

– This is all you can do with it! …… but must be enough to cool your won bottle of wine. 5

We are still looking for a

name. 1 bottle of wine if

you come up with the winning name!

[email protected]

6

HX204

VL209

VL103

Pump control

AC110

HT110

VL105

PM111

VL206

PM101PM102

HX206

CO2 fill port

CO2 from experiment

CO2 toexperiment

Vacuum line

Vent port

By-pass Hot gas by-pass

CO2

cond

ense

r

R404

a con

dens

er

R404a compressor

AccuControl

Enthalpy heater option

PR105

CU201

PR108

PR104

VL204

Sub coolControl

Commercial condensing unit(water cooled / frequency controlled compressor)

FL103

TT101

12

TT103

3

PT103

TT105 5

TT108

8

PT108

TT110

PT110

4

VL111

VL105

67

VL118

6

7

23

8

1

PT205

5

4

Cool

ing

wat

er

HT104

Heater control

TT104

FT103

9

VL118

xxxxx system

[email protected] Set-Point Controls

7

Acc

umul

ator

con

trol

(Pre

ssur

e)

Tsub = -50°C => Enthalpy=135 kJ/kg (Experiment sub cooling request)

Pump sub cooling controlTaccu+Tsub-10 => 20-50-10 = -40°C

Pump sub cooling controlTaccu+Tsub-10 => -20+0-10 = -30°C

3

3

Heater = (Enth request - Enth 3) x Massflow

Heater = (Enth request - Enth 3) x Massflow

Taccu = 20°C

Taccu = -20°C

VQ = 20% => Enthalpy=210 kJ/kg (Experiment vapor quality request)

Tsub = -50°C

10°C

[email protected] Accumulator design and control• Similar to VELO accumulator but with hot gas by-pass for

chiller capacity control.

• Temperature set-point with pressure control.

• Volume ca. 5 liter (PED class II)

• Discussion with CERN central workshop and safety for designing and construction of accumulators at CERN following the PED rules.

8

-120

-80

-40

0

40

80

0 2 4 6 8 10

Only Heating allowed

Cooling possible

State point 1 sub cooling °CSP101.subc = SP110.tsat-TT101.temp)

AC11

0.lli

m

Accumulator PID

If AC110.lmn1 > AC110.ulimAC110.lmn2 = AC110.ulim

elseif AC110.lmn1< AC110.llimAC110.lmn2 = AC110.llim

else AC110.lm2 = AC110.lmn1

end

If AC110.lmn2 > 0AC110.lmnp = AC110.lmn2AC110.lmnn = 0

else AC110.lmn2 < 0AC110.lmnp = 0 AC110.lmnn = AC110.lmn2

end

VL206.pcnt = abs(AC110.lmnn) + VL206.offs

AC110.lmn1

AC110.lmn2

AC110.lmnp

HT110.pcnt = AC110.lmnp

AC110.lmnn

AC11

0.lll

im

AC110.tmsp = AC101.usspAC110.prsp = exp(A+(B/(AC101.tmsp+C)))

%Antoine’s equation% R744 A=10.77 B=-1956 C=271.04

AC11

0.pr

sp

PT110.pres

SP101.tsat

TT101.temp

VL206.pcnt HT110.pcnt

AC101.ussp

020406080

100120

0.04 0.05 0.06 0.07 0.08 0.09

Heater thermal resistance (°C /W)HT110.rthm =(TT110.temp-PT110.tsat)/HT110.watt)

AC11

0.ul

im

AC11

0.ul

im

AC110.ussp = Accumulator user set point temperature (°C)AC110.tmsp = Accumulator temperature set point (°C)AC110.prsp = Accumulator pressure set point (Bar)AC110.lmn1 = PID raw outputAC110.lmn2 = PID limited outputAC110.llim = PLC output variable lower limiterAC110.ulim = PLC output variable upper limiterAC110.lmnp = Positive .lmn variableAC110.lmnn= Negative .lmn variableSP101.subc = State point 1 sub cooling (°C)SP101.tsat = State point 1 saturation temperature (°C)HT110.rthm = Heater thermal resistance (°C /W)VL206.pcnt = Valve setting (%)VL206.offs = Valve offset due to hot gas by-pass (%)HT110.pcnt = Heater setting (%)HT110.watt = Heater power (Watt)

PT110.tsat

TT110.temp

VL209

AC110

HT110

VL206

HX206

Hot gas by-pass

AccuControl

TT101

TT110

PT110

6

7

[email protected] CO2 condenser design and control

• Alfa-laval AXP10-20 high pressure heat exchanger (120 bar)

• CO2 sub cooled liquid control with R404a injection

• Temperature set point of PID controller determined by system.

• Tpumpinlet = Taccu + Tsubcooling – 10°C

9

HX204

PM101CO

2co

nden

ser

VL204

Sub coolControl

TT101

1

PT205

5

4

[email protected] Pump mass flow control• Two pumps in series to boost pressure

drop

• Gather 1m-J/12-11/x-ss/s/q/k200/DLC gear pumps with integral DC drive

• Massflow controlled with Rheonik massflow meter

10

VL103

Pump control

PM101PM102

CO2 fill port

FT103FL103

TT101

12

TT103

3

PT103

4

250 rpm500 rpm750 rpm1000 rpm1250 rpm

1500 rpm

1750 rpm

2000 rpm

2250 rpm

2500 rpm

R0R1R2R3R4

R5

R6

R7R8R9R10

R11

0

2

4

6

8

10

12

14

16

18

20

-2 0 2 4 6 8 10 12 14 16

ΔP

(bar

)

Flow (cm3/sec)

0 rpm250 rpm500 rpm

750 rpm

1000 rpm

1250 rpm

1500 rpm

1750 rpm

2000 rpm

2250 rpm

2500 rpm

R0

R1R2

R3

R4

R5R6R7

0

2

4

6

8

10

12

14

16

18

20

-2 0 2 4 6 8 10 12 14 16Δ

P (b

ar)

Flow (cm3/sec)

Single pump

Dual pump

[email protected] Condensing unit

• Water cooled R404a or CO2 chiller

• Frequency controlled compressor to minimize base load.

• Investigating Sanyo 2-stage CO2 compressor with inverter for xxxxx cooler.

• Frequency controlled Maneurop compressor selected for XFEL cooler. Test chiller is ordered for condenser control and hot gas by-pass tests.

11

0

500

1000

1500

2000

2500

3000

3500

4000

-45 -40 -35 -30 -25 -20 -15 -10 -5 0

Cool

ing

capa

city

(W)

Evaporation temperature ('C)

Maneurop VTZ038/R507a performance (Tcondens=30'C)

85Hz

35Hz

Dummy load (840W)By hotgas bypass

Ptotal (1.6kW @-25)

[email protected] Enthalpy heater control

• User input –yy to +xx-yy = subcooling (ºC), +xx = vapor quality (%)0 = saturation line

• Set points translated to enthalpy with respect accumulator pressure.

• Heater power is calculated by input condition (Enthalpy point 3 and mass flow) -> No PID control.

• DC-power for smooth heating (pulse heater influences mass flow and thus the heater control itself)

12

PR104

TT105 5

4

HT104

Heater control

TT104

FT103

TT103

3

PT103

[email protected]

xxxxx versus XFEL cooler

13

CERN-DT xxxxx system

Nikhef/Desy XFEL Difference in the design

Temperature range -40ºC to +25ºC -15ºC to +20ºC Different chiller

Cooling power 1kW 1.2kW Different chiller

Pump pressure head

10 bar 5 bar 2 serial pumps versus 1 pump

Fluid condition Sub cooled liquid to X=0.5

X=0, Saturated liquid

Heater instead of heat exchanger

Enthalpy

CERN-DT xxxxx system

Liquid Vapor

2-phase

Pre

ssur

e

Enthalpy

Nikhef/Desy XFEL system

Liquid Vapor

2-phase

Pre

ssur

e

[email protected]

14

HX204

VL209

VL103

Pump control

AC110

HT110

VL105

PM111

VL206

PM101PM102

HX206

CO2 fill port

CO2 from experiment

CO2 toexperiment

Vacuum line

Vent port


CO2

cond

ense

r

R404

a con

dens

er

R404a compressor

AccuControl

Enthalpy heater option

PR105

CU201

PR108

PR104

VL204

Sub coolControl


FL103

TT101

12

TT103

3

PT103

TT105 5

TT108

8

PT108

TT110

PT110

4

VL111

VL105

67

VL118

6

7

23

8

1

PT205

5

4

Cool

ing

wat

er

HT104Heater control

TT104

FT103

9

VL118

HX204

HX104

VL209

VL103

Pump control

AC110

HT110

VL105

PM111

VL206

PM101

HX206

CO2 fill port

CO2 from experiment

CO2 toexperiment

Vacuum line

Vent port


CO2

cond

ense

r

R404

a con

dens

er

R404a compressor

AccuControl

Desy-XFEL option

PR105

CU201

PR108

PR104

VL204

Sub coolControl


FT103FL103

TT101

12

TT103

3

PT103

TT105 5

9

TT108

8

PT108

TT110

PT110

4

VL111

VL105

67

VL118

6

7

23

8

1

PT205

5

4

Cool

ing

wat

er

Heater vs heat exchanger

2 vs 1 pump

1kW@-45ºC vs 1.2 kW@-25ºC

xxxxx system

XFEL system

Differences will be designed to be interchangeable: 1 common mechanical (and control?) design

• Designer from Krakow will arrive

1st of November at CERN.• Nikhef has also assigned 1

FTE.

[email protected] The portable 100W “Mini -xxxxx” system

• Development of the 100W system will be a simplified concept wrt the 1kW xxxxx system. Controls are reduced to a minimum. (Goal is no PLC).

• Collaboration with LHCb for the VELO upgrade development. Raphael is working on design.

• Volume is small so everything fits in the lowest PED class (Article 3.1).

• The goal is to have 100W@ -40°C, and a temperature range between 25°C and -40°C.

• Same pump and heat exchanger type as xxxxx system, but smallest in range.

15

[email protected]

Future developments

• Future systems will have a large increase of power and volume.

• Especially large volume pipes (reuse of CMS pipes) will demand for large volume accumulators.

• The CMS low pressure requirement, requires emptying of the system at standstill. This demands for even larger accumulators.

• Therefore room temperature accumulation is under study.

16

[email protected] 2PACL State point model in Matlab

• To support future system development a simulation is developed in Matlab to study state point values of a full loop.

• At each state point the pressure and enthalpy are calculated iteratively according to the properties at the given state-points. Integrated Refprop database

• Model can be sub divided in small sections of dL to accurately calculate the fluid state at any place in the loop. Environmental heat is included.

• General configuration file as input giving tube information (lengths, diameter and isolation), flow restrictions (Cv), heat exchange(external or internal), pump performance.

17

[email protected]

Matlab state point model

18

Px,Hx

Px+1 = Px - dPx

Hx+1 = Hx + dHx

Qx = Qapplied + Qenvironment +Qexchanged

dPx = f(D,Q1,MF,VQ,P,T) or f(Cv)

dHx = Qtot/MF or pump work

dPpump=∑dPall

dHcondenser = ∑dHall

Tx,VQx and properties derived from Refprop

Qx+1

dPx+1

dHx+1

Px+2,Hx+2

Current status:All latest Thome models (dP, HTC) are being implemented (Joao@portugal), Model currently works with old models (Friedel & Kandlikar from the LHCb-velo stone ages)

[email protected] Typical state point model inputExcel configuration file

19

State point Identifier

Identifier number

Pressure reference

Temperature reference L(m) DO(") DO(m) DI(m) Dh(m)

Qty of paralel tubes

Crossectional Area Per tube (m2)

Vol tubes (m3)

Vol rest (m3)

Volume total (m3)

Wetted area Per tube (m2)

Outside area per tube(m2)

Isolation thickness (m)

Lambda pipe (W/mK)

Lambda Isolation (W/mK)

Applied heat (W)

Volume flow (m3/s)

Cv-value

Exchange heat with node#

Co-currentflow (1), Contercurrentflow (-1)

1 tube 1 1 1 1/40.00635

0.00457

0.00457 1

1.6403E-05

1.6403E-05 0

1.6403E-05

2.50E-02 16 0.04 0

2 pump 2 0 02.50E-

02 0.04 709.62113

E-06

3 tube 1 2 1/40.00635

0.00457

0.00457 1

1.6403E-05

3.28059E-05 0

3.2806E-05

2.50E-02 16 0.04 0

4 tube 1 50.5 1/40.00635

0.00457

0.00457 1

1.6403E-05

0.00082835 0

0.00082835 16 0 11 -1

5 tube 1 2 1/40.00635

0.00457

0.00457 1

1.6403E-05

3.28059E-05 0

3.2806E-05

2.50E-02 16 0.04 0

6 restriction 3 0 0 0 0.05

7 tube 1 1 1/40.00635

0.00457

0.00457 1

1.6403E-05

1.6403E-05 0

1.6403E-05

2.50E-02 16 0.04 0

8 tube 1 21.00E-03

5.00E-04 0.000523

1.9635E-07

3.92699E-07 0

3.927E-07 16 0

9 tube 1 11.50E-03

1.00E-03 0.001 23

7.854E-07

7.85398E-07 0

7.854E-07 16 800

10 tube 1 3 3/80.009525

0.00775

0.00775 1

4.7173E-05

0.000141519 0

0.00014152

2.50E-02 16 0.04 0

11 tube 1 50.51.60E-02

1.40E-02

0.00765 1

1.22E-04

0.006174576 0

0.00617458

2.50E-02 16 0.04 0

12 tube 1 1 3 3/80.009525

0.00775

0.00775 1

4.7173E-05

0.000141519 0

0.00014152

2.50E-02 16 0.04 0

13 condenser 43.00E-

04 0.0003 84000 840002.50E-

02 0.04 0

[email protected] Typical state-point model output (LHCb-VELO)

20

1

2 3

4 5

6 789

X=0.1 X=0.2 X=0.310.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0 150.0 200.0 250.0 300.0

Pres

sure

(Bar

)Enthalpy (kJ/kg)

TL operation in PH-diagram TL State points

T=-39.5°C

T=26°C

Tsatliq1

2 3

4 5

6789

X=0.1

X=0.1

X=0.2

X=0.2

X=0.310.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0 150.0 200.0 250.0 300.0

Pres

sure

(Bar

)

Enthalpy (kJ/kg)


T=-39.5°C

T=-6.9°C

Tsatliq

1

2 3

4 5

6 789

X=0.1

X=0.1

X=0.2

X=0.2

X=0.310.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0 150.0 200.0 250.0 300.0

Pres

sure

(Bar

)

Enthalpy (kJ/kg)


T=-39.5°C

T=-10°C

Tsatliq

1

2 3

4 5

6789

X=0.1

X=0.1

X=0.2

X=0.2

X=0.310.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0 150.0 200.0 250.0 300.0

Pres

sure

(Bar

)Enthalpy (kJ/kg)


T=-39.5°C

T=-10°C

Tsatliq

1

2 3

4 5

6 7 89

X=0.1

X=0.1

X=0.2

X=0.2

X=0.3

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0 150.0 200.0 250.0 300.0

Pres

sure

(Bar

)

Enthalpy (kJ/kg)


T=-39.5°C

T=-29.9°C

Tsatliq

1

2 3

4 5

67 89

X=0.1

X=0.1

X=0.2

X=0.2

X=0.3

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0 150.0 200.0 250.0 300.0

Pres

sure

(Bar

)

Enthalpy (kJ/kg)


T=-39.5°C

T=-29.9°C

Tsatliq

Feed line in (2)

→← Return line in (7)

26

-40

-30

-20

-10

0

10

20

30

0

40

80

120

160

200

240

280

0 10 20 30 40 50

Tem

pera

ture

(°C

)

Hea

t (W

att)

Transfer tube length (m)

Transferred heat (Watt) Environemental heat (Watt)Feed line temperature (°C ) Return line temperature (°C )Setpoint temperature (°C )

Feed line in (2)

→

← Return line in (7)-10

-40

-35

-30

-25

-20

-15

-10

-5

0

40

80

120

160

200

240

280

0 10 20 30 40 50

Tem

pera

ture

(°C

)

Heat

(Watt

)



Feed line in (2)→

← Return line in (7)-30

-40

-35

-30

-25

-20

-15

-10

-5

0

40

80

120

160

200

240

280

0 10 20 30 40 50

Tem

pera

ture

(°C

)

Heat

(Watt

)



State points in PH-diagram

Subdivision details of transfer line

Tsub=-40°C, Taccu=26°C

Tsub=-40°C, Taccu=-10°C

Tsub=-40°C, Taccu=-30°C

[email protected]

Summary

• 2 operational CO2 systems @ CERN

• 2 new laboratory CO2 systems under development (1kW@ -40°C & 100W@ -40°C)

• Scaling up 2PACL for the future

• Prototyping of different concepts

• Development of a state point model with latest Thome models to investigate new cycles

21

[email protected]

22

[email protected]

Documents

Bart Verlaat 13 October 2010