1. Evaporative Heater Design, qualification and planning M.Olcese PRR SCT off-detector cooling PRR SCT off-detector cooling 13-14 March 2005 13-14 March 2005

2. PRR SCT cooling 13-14 Mar 2005 M.Olcese2 Heater function and location  The heater is a critical component for the evaporative system: it allows to evaporate the residual liquid after the HEX and to raise the vapor temperature at the exhaust above the cavern dew point  There is one heater per circuit: if an heater is not working properly we’ll probably have to switch off the relevant circuit

3. PRR SCT cooling 13-14 Mar 2005 M.Olcese3 Heater design  Heating wire coiled inside the return tube  Powered 100 VDC in switching mode and controlled by a PLC  Power duty cycle adjusted as function of the load on the detector to keep the temperature of the exhaust vapor as close as possible to the ambient temperature  Temperature feedback provided by two thermocouples reading the vapor temperature downstream the heating coil  One thermocouple is used for the control the second for interlock  In case of failure of one of the sensors the control and interlock functions are cumulated on the remaining sensor, but the interlock remains independent from the PLC

4. PRR SCT cooling 13-14 Mar 2005 M.Olcese4 History  First idea to use a heater with a coiled heating wire inside the return tube is dated 3 years ago  Since then two sets of prototypes have been made, the second one has been used to fully qualify the heater design and the control system  A final set of two prototypes has been ordered to perform final check of performances before placing the production orders Qualified heater design

5. PRR SCT cooling 13-14 Mar 2005 M.Olcese5 Prototype qualification: tested parameters  Temperature of heating element  Pressure drops  Stability of the control system  Position of the temperature feedback sensor  Max stable duty cycle (min power difference between the nominal and maximum)

6. PRR SCT cooling 13-14 Mar 2005 M.Olcese6 Measurements (T,Dp)  Two prototype with different size and power  The small heater has one thermocouple head welded on the heating element Both heaters are too small: too high pressure drops (budget 50 mbar) Temperatures of heating element are low, but proportional to Re

7. PRR SCT cooling 13-14 Mar 2005 M.Olcese7 Extrapolation to final design Size increased to decrease pressure drops Tubes standardized to two sizes only

8. PRR SCT cooling 13-14 Mar 2005 M.Olcese8 Extrapolated temperatures SCT EC temperatures close to 100 °C Fluid limit is about 120 °C Decreasing ID by 1 mm the temperature lowers by 20 °C (and the pressure drops increase to 80 mbar) Wait tests on final prototype to take decision

9. PRR SCT cooling 13-14 Mar 2005 M.Olcese9 Heater control tests  PLC with simple control algorithm works properly also with very long temperature readout cables (150m)  Average vapor temperature (and wall temperature) function of power load on stave with constant T set point: need variable set to minimize  T  Stability good even against sudden load change and with T feedback sensor far from the exit  Control OK up to a duty cycle of 95%

10. PRR SCT cooling 13-14 Mar 2005 M.Olcese10 SCT barrel layout  All details fully finalized, including layout electrical connectors

11. PRR SCT cooling 13-14 Mar 2005 M.Olcese11 Design of barrel heater Long type short type Only two types

12. PRR SCT cooling 13-14 Mar 2005 M.Olcese12 SCT EC heater design  Various versions differing by the shape of the exhaust tube (driven by PPF1 layout)  Fittings are defined  Layout at PPF1 still not finalized (needed to fix no. of versions, position of electrical connectors)  Still unclear if the tube OD needs to decrease by 1 mm (see later)

13. PRR SCT cooling 13-14 Mar 2005 M.Olcese13 SCT EC layout Tubes from heaters to PPF1 have different shapes due to the layout of fittings at PPF1

14. PRR SCT cooling 13-14 Mar 2005 M.Olcese14 Summary of heater types  4 main classes of power  A multiplicity of subtypes due to different shape of tube extensions due to tight layout

15. PRR SCT cooling 13-14 Mar 2005 M.Olcese15 Overall status (critical items in red)  Final prototypes ordered: delivery mid April  Testing of final prototypes should be completed by end of April as part of an SCT EC system test with pre-production HEX and real on-detector loops  Design of SCT barrel heaters is ready, EC SCT and pixel design (layout) still to be finalized  Very specialized work: we have been dealing with only one company so far. Difficult to find qualified alternatives  Updated cost estimate from Thermocoax is 1500 Euro per heater.  We do not need to go through a formal tendering, but a price enquire will be done anyway trying to reduce the price  Plan to place orders end of April/beginning of May (lead time 5 months)  All heaters needed by end of the year to allow the full system commissioning before the ID installation

16. PRR SCT cooling 13-14 Mar 2005 M.Olcese16 Heaters are needed for final commissioning of cooling system before detector installation Main cooling plant and control Heater control Heater power supplies Distribution racks US15 USA15UX15 platforms On-detector loops and capillaries heaters pipework cabling Heat exchangers  Start: Dec `05  Finish: Mar `06  Responsibility: ID/TS-CV  Need dummy capillaries  Need supports for heaters of SCT-EC and pixel (dismounted after)  Goal: check full functionality of all circuits in warm and cold mode (test of heater possible only at max power)