SPD cooling Test bench Preliminary results CERN (Geneva) A.Francescon Università & INFN Padova 1

Summary Description of the test bench experimental setup Clean filters characterization Masked filters tests Pollution test 2

Why a test bench Problems in the SPD cooling system (and related losses in detection efficiency) + Difficult theoretical evaluation of the problem = Experimental test bench 3

The plant The ideal plant: -Exact replica of the real plant -Many measuring points (T, p, flow) along the stave and the whole plant Temporary plant: -Similar to the real plant (smaller scale) -Many measuring points -Being upgraded for larger flow Meanwhile: We use a thermosiphon plant built by the EN/CV/DC group 4

Two-phase thermosiphon plant Chiller Condenser Dummy Load Natural circulation of the Fluid (C4F10) - On the liquid phase by gravity - On the gas phase by pressure difference 5

Test bench schema PP4 filter and pressure PP3 filter and pressure 6

Test bench 7

Setup characteristics 1)Available pressure difference (supply-return) dp= ~ 2,5 bar 2) Nominal flow ~ 3,7 g/s (without filters) 3) The sector is an exact replica of an SPD sector from the mechanical/hydraulic point of view; The only difference is that in this case power on the sector is not generated by the detector but with a power supply (so the power can be adjusted very simply). 8

Filters characterization Clean 60 um filterClean 20 um filter 9

Filters characterization N.B. This is the situation that we have now in the cavern: -60 um filter in PP4 -60 um filter in PP3 N.B. Dp is measured only on the secon filter (PP3). Two 60 um clean filters in series 10

Filter Dp and flow variations with the power applied to the sector 60 um clean filter 0,5 g/s decrease 100 mbar decrease 11

Flow variations with the power applied to the sector for different flowrate Clean 60 um filter 12

Impedance of different filter combinations 13

Bubbles formation bar Closing point °C Closing point 14

Bubbles formation point on the p-h diagram Liquid Liquid+ Gas Gas T=18°C P=2,13 bar 15

Masked filters 3 different type of masked filter used (all clogged with epoxy glue): -Spot masked filter: filter clogged with 6 dot (dot diameter ~1 mm & clogged surface ~50% ) -Diffuse masked filter: filter clogged in a diffusive way (clogged surface ~50%) -Center masked filter: filter clogged in the middle part of the surface (clogged surface ~65%) Spot filter Center filter 16

Influence of the clogging type on the flow 17

Dp vs Flow for different clogged filters 18

Pollution tests 4 kind of Goodfellow calibrated metal particles: 1)0,4-12 um carbon vitreous powder 2)20-50 um carbon vitreous powder 3) um carbon vitreous powder <75 um carbon powder 4)<75 um carbon powder Test procedure: 1) The powder has been introduced in the pipe upstream both filters 2) Vacumm has been made downstream both filters 3) Flow and Dp across the PP3 filter has been evaluated for different flowrate and different power applied to the sector 19

Powder sample Due to technical problems -Difficult handling of very small particles -Powder adehesion on the pipe wall and on the instruments -… the real amount of powder is ~50%. 0,4-12 um carbon vitreous powder 0,25 g of powder 20

After the insertion of 0,25 g (nominal) of 0,4-12 um carbon vitreous powder N.B. With clean 60 um filter and clean circuit: Valve fully open PP4=3,67 bar Dp=0,48 bar Flow=3,5 g/s With epoxy glue 50% diffuse clogged filter: Valve fully open PP4=3,665 bar Dp=0,484 Flow=3,368 g/s After the insertion 0,5 g (nominal) of powder: Valve fully open PP4=2,47 bar Dp=0,355 Flow=1,155 Pollution test: 0,4-12 um 21

Pollution test: um Stop&Start 22

Pollution test: um I,II and III insertion Steps 23

Pollution test: <75 um I insertion III insertion 24 Stepsteps

Pollution test: 0,4-12 um (small amount) Powder insertion Stop&Start Stop&Start with vacuum 25

Inserted another little amount (~ 0,05 g) of 0,4-12 um carbon powder NotePower [W] PP4 [bar]Dp [bar]Flow [g/s] Powder inserted0 W2,3150,0500,650 Stop&Start with pipe shaking0 W2,2700,0500,495 PP4 filter placed in PP3 position 0 W4,0451,5191,484 26

Conclusions Powder clogging results to be more effective than epoxy glue clogging Powder crossing through the PP4 filter and following deposition on PP3 filter observed Flow variation with Stop&Start observed 27

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Filter characterization 29

Clean 20 um filter 30

Two clean 60 um filter in series 31

Spot clogged filter: filter clogged with 6 dot (approx. diameter 1 mm & approx. clogged surface 50% ) 32

Center clogged filter: filter clogged in the middle part of the surface (approx. clogged surface 65%) 33

0,4-12 um carbon vitreous powder 0,25 g of powder 34

Diffuse clogged filter: filter clogged with 6 dot (approx. diameter 1 mm & approx. clogged surface 50% ) 35

Two portions Of 0,4-12 um carbon powder inserted in the same time (0,5 g in total) PP4 [bar] 36

um carbon vitreous powder 0,2 g inserted in different times NotePower [W] PP4 [bar]Dp [bar]Flow [g/s] I insertion0 W3,3600,4982, W3,3900,4702,715 II insertion0 W3,3050,4602,8 100 W3,3500,4302,684 Stop&Start0 W3,2800,4602,815 NIGHT STOP Restart after vacuum 0 W3,3100,4902,778 III insertion0 W2,1850,0730, W2,2240,0750,749 37

-75 um carbon powder ~ 0,15 g inserted in different times NotePower [W]PP4 [bar]Dp [bar]Flow [g/s] I insertion0 W2,7770,1732, W2,8220,1692,192 II insertion0 W2,7420,1722, W2,8020,1662,132 III insertion0 W2,5650,1471, W2,6240,1381,839 IV insertion0 W2,4220,1021, W2,4640,1011,457 38

20-50 um carbon vitreous powder ~ 0,15 g inserted in different times NotePower [W]PP4 [bar]Dp [bar]Flow [g/s] I insertion0 W3,0150,2172, W3,0750,2042,551 II insertion0 W2,6500,1462, W2,7150,1382,065 III insertion0 W2,1680,0320, W2,1900,0300,895 Stop&Start0 W2,1380,0400,795 39

Test with a little amount (~ 0,05 g) of 0,4-12 um carbon powder NotePower [W]PP4 [bar]Dp [bar]Flow [g/s] Starting condition (before inserting powder) 0 W3,3120,3113,026 Powder insertion0 W3,0310,3372,495 Stop&Start0 W2,8850,3232,238 Stop&Start0 W3,3730,6632,489 Stop&Start with vacuum0 W3,1620,5402,060 Stop&Start0 W3,4630,6852,255 Start&Stop with vacuum (PP3 filter replaced) 0 W3,1200,2242,600 Stop&Start (with pipe shaking) 0 W3,1340,2362,670 40