LHCb-VELO Microchannel fracture safety system and evaporator concept 26 June 2015 Bart Verlaat 1

Microchannel volume (1) The minimum volume which we can shut-off is 1 u-channel including the in and outlet pipes. The worst case is a filling of cold liquid –T-30ºC liquid (1076 kg/m 3 ) used in analyses –Under normal circumstances vapor is present and less CO2 is present. Assuming a 0.5mm inlet and 1.2mm outlet (1m long) –See quick CoBra analyses 2

Microchannel volume (2) Module volumes and CO 2 -30ºC liquid (1076 kg/m 3 ): –Inlet: D0.5mm x 1m = 0.2 ml 0.21 gram –μ-channel: 19x (60μm* 60μm*30mm+120μm*200μm*267mm) = 0.12 ml 0.13 gram –Outlet: D1.2mm x 1m = 1.1 ml 1.2 gram –Total module volume: 1.6 gram CO2 total Vacuum volumes (Eddy Jans memo, 5 November 2009) : –Secondary: 450 liter –Primary: 1715 liter –Maximum dP=10 mbar Loosing 1.6 gram of CO2 in the secondary volume gives a density of 1.6 g / 450 l = 3.5 g/m3 –3.5 g/m3 density after warming up to 20’C gives a pressure of 1.9mbar –Direct expansion without heat pick-up is Conclusion: 1 μ-channel leak is not critical! But a proper module shut-off mechanism is needed 3

Venting CO 2 in vacuum g/m3 => v=285 m3/kg Far off scale Ca 350 kJ/kg*1.6 g = 560 J to heat it up to ambient. Condition of -30 ⁰ C liquid Condition of +20 ⁰ C low pressure gas

How can we isolate 1 μ-channel? 3 module shut-off options: –Place no-return valves at each module inlet and outlet Will add the inlet manifold volume to the leaking volume 1 critical active common inlet valve No risk of liquid trapping Need a reliable miniature no return valve –Place a shut-off valve at the inlet and protect the outlet return flow with a no-return valve No risk of liquid trapping Need a reliable miniature no return valve Many active valves in the vacuum –Place shut-off valves at each module inlet and outlet Risk of liquid trap Many active valves in the vacuum For safe operation: –A relieve: risk of leak or an atmospheric back flow. –A safety gas volume: need a small heat source to keep it filled with gas (might be ambient) 5

No return valve option This concept requires small passive no return valves. Actuator can be out of the tertiary vacuum Inlet manifold will be leaked into the vacuum as well: –Assuming a 4x0.7 tube & 1m long –Extra Volume: 5.3 ml = 5.7 gram –Pressure in secondary 20’C = 8.9 mbar 6 1 Active NC valve needed and many miniature no return valves Red volume will leak in vacuum Green volume can stay pressurized. An additional pressure relieve can be included Ambient Tertiary vacuum Secondary Vacuum Valve is NC and actuated when a pressure increase in the Velo is detected. Eg. 1e-3mbar

Individual inlet shut-off This concept requires small passive no return valves. 26 actuators in the tertiary vacuum –Pneumatic valves very complex in a vacuum –Electrical valves NC have a constant heat load on the CO2 inlet Small volume leaked into vacuum –Pressure in secondary 20’C = 1.9 mbar 7 26 Active NC valves needed in vacuum and 26 miniature no return valves Red volume will leak in vacuum Green volume can stay pressurized. An additional pressure relieve can be included Ambient Tertiary vacuum Secondary Vacuum Valves are NC and actuated when a pressure increase in the Velo is detected. Eg. 1e-3mbar

Full active shut-off This concept is very sensitive for trapping cold liquid –Each line needs a relieve mechanism –Open relieve mechanisms (Burst disc or safety valves) are a risk for the modules (sudden cool down when activated) –A warm safety volume is an option 52 Actuators in the tertiary vacuum –Pneumatic valves very complex in a vacuum –Electrical valves NC have a constant heat load on the CO2 inlet Small volume leaked into vacuum –Pressure in secondary 20’C = 1.9 mbar 8 52 Active NC valves needed in vacuum Red volume will leak in vacuum Green volume can stay pressurized. An additional pressure relieve can be included Ambient Tertiary vacuum Secondary Vacuum Valves are NC and actuated when a pressure increase in the Velo is detected. Eg. 1e-3mbar Safety volume always contains warm gas

All Upgrade Velo cooling vs current Velo cooling 9 All inlet capillaries on 1 side. Return common (Manifold inside) Electronics crates Cable feedthrough Tertiary vacuum with manifolds and safety valves Cooling feed through with thermal stand-off Out of the way space for cooling connector and flexible part Cooling lines passing the module base on the side

Safety system continued The all no-return valve option seems optional and favorable (option 1) –Simplest from control point of view No active parts in vacuum –Need to develop a reliable miniature no-return valve A small leak rate still tolerable as the vacuum pump continues pumping (Ca. 10 mg/s allowed) Other options require many active valves (26 or 52) all in vacuum. 10

CO 2 pumping in secondary vacuum 11 Pressure (mbar) Mass flow (g/s) ACP 28 pumping capacity for CO 2 A constant CO 2 leak of 10 mg/s is tolerable At least 1 ACP28 pump is active, sometimes 2 work in parallel

Concept Evaporator P&ID 12 vent 6 8 ⅜” EH106 TT106 TS PV110 BD108 PT108 TT108 PV108 PV144 SV042 SV043 MV042 AV108 nc MV050 MV052 TT35036 NV110 MV110 CV142 nc no ¼” ½” PT050 To UT-Detector EH39052 TT39052 CV39052 EH30036 CV30038 PV30038 NV30142 NV30148 NV30242 NV30248 NV30342 NV30348 nc EH35036 CV35038 PV35038 NV35142 NV35148 NV35242 NV35248 NV35342 NV35348 PV35052 nc PV35040 nc PV35050 nc PV39060 nc PV39030 nc PV30040 nc PV30050 PV59032 PV59054 PV49060 PV49030 nc 36 PT35052 TT35052 BD PT35038 TT SA35052 SA30052 PT30038 TT Safety vent By-pass with dummy load Pre-heater Safety vent Pre-heater nc PV PT30052 TT30052 BD30052 TT39032 PT39032 BD TT PT39058 TT39058 BD Vacuum Ambient

P&ID explained Labelling (QQxyyzz) –QQ=component PV=Pressure valve CV=Control Valve NV=No Return Valve TT=Temperature transmitter PT=Pressure Transmitter EH=Electrical Heater SA=Safety Accumulator –x=System ID 1=Chiller A 2=Chiller B 3=CO2 Velo 4=CO2 UT 4=CO2 Common 6=Dry-air 7=Tertiary Vacuum –yy=Branch ID 00 = Aside common 01…26 = Evaporator 1 to 26, A side 50 = C –side common = Evaporator 1 to 26, C side 90 = General (Inlet, By-pass & return) UT and Velo can be connected at the level of the accumulator –PV59054 & PV59032 open –Close the PV39030 & PV39058 incase of Velo failure or visa versa Preheater EH30036 & EH35036 regulate TT30036 & TT35036 The Pressure difference (PT39032-PT39058) is regulated constant with CV39052 –CV30038 & CV35038 are set constant for a certain evaporator flow –The constant dP allow the sharing of the UT Safety procedure –If P vacuum >10 -3 mbar, then close PV30038, PV35038, PV30052 &, PV35052 –If PT30038 < PT39058 – 3bar, then open PV30040 & PV30050; This means there is a leak in this section –If PT35038 < PT39058 – 3bar, then open PV35040 & PV35050; This means there is a leak in this section –System remains running over by-pass, to stay active for safety control and UT operation –The safety procedure is safe by default valve position (No venting), Venting is done in addition to be more safe. A safe vent action requires NO valves, but than there is a high risk of unwanted venting which is a hazard for the modules as a cool down is a result. A safety accumulator in the module section must prevent accidental liquid trap. The SA has always a gas filling. 13