Detailed Design Review

1. Detailed Design Review P13681

2. Austin Frazer • Role: Lead Engineer - Analysis • Major: Mechanical Engineering • Eileen Kobal • Role: Lead Engineer – Mixtures of Gas Fluids • Major: Chemical Engineering • Ana Maria Maldonado • Role: Team Manager • Major: Industrial Engineering • Marie Rohrbaugh • Role: Project Manager • Major: Mechanical Engineering The Team

3. Agenda for the review • Overview of the Project • Our system designs • Part designs • Lab View layout • Bill of Materials • Test plans • Risk Assessment • Schedule for the rest of the Project

4. UUT Problem Statement Fixtures interface between AGT can and UUT Fixturing/leakage similar to other side UUT leakage Fixture leakage To mass spectrometer High pressure helium High pressure helium Leakage from Unit UnderTest Leakage from Fixture Leakage from room through lid and baseplate

5. Project Overview

6. Matlab/Simulink Model

7. Flow Sensor The System • We require a means to distinguish between the top two generated concepts. Consequently, a math model of the system was created. • Results must be an improvement from the baseline 0 psi (Vacuum) Case 1) 14.7 psi (ambient) Case 2) 0 psi (Vacuum) Case 3) Variable pressure/vacuum (nitrogen) 3000 psi

8. Orifices 1 and 2: Model Oring Leakage. Simplification of the System 3000 psi 0 psi (To Mass Spectrometer) Entire Vent Volume Flow Sensor • Orings will be models as (very) small orifices • Molar percentages must be taken into consideration for all three cases (compare apples to apples) MIXTURE HELIUM Orifice 3 : Accurately simulates uniformly mixed flow out of vent.

9. 0 psi (To Mass Spectrometer) 3000 psi Parameters and Equations Entire Vent Volume Ideal Gas Law: Mixed Density Calculation: Orifice area, Ao, is adjusted for the oring and vent orifices to produce accurate molar flow rates

10. Assumptions • Most Importantly: This is a pressure driven flow • Permeability considerations were made (Parker equations from design review). The leakage rates predicted through the Orings were too small. • Perfect gas mixture throughout the volume at all times • N2 and He are ideal gases

11. The Simulation Molar flow rate of helium into vent (3000 psi) Molar flow rate of gas into can calculator He Integrator N2 Integrator Molar flow rate of gas into/out of vent Calculates % Moles Calculates Mixed Density

12. Case 1: Ambient Vent Pressure • High vent pressure causes more total leakage than Case 2 • More nitrogen is present; concentration of helium grows slower than in Case 2 Red Dots: Helium Blue Dots: Nitrogen ≈ 14.8 psi ≈ 14.8 psi 14.7 psi ≈ 14.8 psi 14.7 psi • Case 2: Vacuum Vent Pressure • Low vent pressure causes less total leakage than Case 1 • Less nitrogen is present; concentration of helium grows faster than in Case 1 Moderately High % Helium 14.7 psi ≈ 14.8 psi ≈ 1.1 psi ≈ 1.1 psi 1 psi 1 psi Very High % Helium 1 psi *Note: Hein remains (approximately) constant for both cases

13. Total Molar Flow Rate Into Can • Question arises: Is it better to have a lower total leakage (lower vent pressure) or a lower percentage of helium in the vent? • The simulation should answer this question • Below is a plot of the actual molar flow rates into the can Note the order of magnitude As expected, the total molar flow rate is less for Case 2

14. % Helium in Can Note the order of magnitude • The concentration of helium grows at a rapid rate when less N2 is present in the vent • At the beginning of the response, Case 2 exhibits a lower concentration of helium than Case 1

15. What Does This Tell Us? Graphed below are the results for the volume of the total leakage for cases 1 and 2: • Over the full interval, the model predicts that Case 2 • An improvement is not expected for a constant vacuum scenario. A constant vacuum does show an improvement in can leakage for the full test duration • This duration of this improvement grows as the vent volume is increased Full 6 Minutes Early Region (2.5 seconds)

16. Cases 1 and 2 With Increased Vent Volume • For a significantly increased volume: The positive influence of Case 2 lasts for approximately 175 seconds (as opposed to 2 seconds). That being said, the remainder of the results will assume that the vent volume is the nominal calculated value (8.49E-7 m3)

17. Cases 1 and 2 Conclusions • Concentration of helium in vent dominates the response of the simulation • Case 2 would show a significant improvement over Case 1 if: • The % He was allowed to grow near 100% in both cases (within the allotted time interval) • The vent volume was significantly increased • A Case is needed which actively reduces the concentration of helium in the vent. A marked improvement over Case 1 is expected

18. Case 3 Concept • Nitrogen is forced in at above ambient pressure: % Helium increases over time • Uniform mixture of gas molecules are removed from the vent: % Helium remains about same. ≈ 120 psi Mixture 120 psi N2 ≈ 1 psi Mixture

19. Case 3 Concept Continued • Nitrogen is once again forced into the vent: % Helium Drops (Note total percentage still > step 1) • Repeat step 2 and 3 throughout the 6 minute external leakage test. The percentage of helium will inevitably grow, but at a slower rate than cases 1 or 2. ≈ 120 psi Mixture

20. Determining the Frequency of Pulse/Purge • Previous slides indicated that pulling a vacuum is only beneficial for approximately 2 seconds. Consequently the following duty cycles for varying input signal periods were calculated: • Values of 120 psi pulse pressure and 1 psi purge pressure were selected 120 psi 1 psi 1 Period

21. Case 3 Results Integration

22. Case 1 to Case 3 Comparison • The best curves of Case 3 are now compared to baseline: • A significant improvement is noted for Case 3

23. Simulation Conclusion • A case 3 scenario shows a marked improvement over the current setup • This model will be used as a tool in MSDII to fine tune the system to optimize can leakage prevention

24. Areas of Desired Feedback • After seeing the results, is the magnitude of can leakage accurate? • If not, the size of the orifices will be adjusted accordingly • Is the 8.49E-7 m3 vent volume accurate? Note that this is 84.7 mm3

25. System Layout

26. Cycling Valve GN2 To the small o-ring Vacuum

27. Enclosure

28. Pipeline model Wires exit rear 2-way valve Regulator 3-way valve Some type of relief structure will be in place here 2-way valve From Nitrogen Source From Vacuum Source To large o-ring To small vent

29. Mounting to the can

30. Through the Manifold

31. Port Blocks

32. The Plug

33. Mounting to the side of the can

34. Pressure Vessel Analysis: Plug • A pressure vessel analysis was ran for the plug geometry. This geometry was selected due to the thin walls • Due to the thin walls this is considered the worst case geometry • Failure margins were calculated with a 1.1 factor of safety. Note all margins are positive.

35. Material Properties • Plugs assumed to be machined from structural steel (properties taken from ANSYS library): • Fty= 36.3 ksi • Ftu= 66.7 ksi • μ = 0.3 • E = 2.9E7 psi

36. Mesh • 472699 Nodes • 311215 Tetrahedral Elements (Overkill) 2 cells through thickness achieved

37. Loads and Boundary Conditions Nominal Loading Worst Case Loading Fixed Support

38. Nominal Loading Results Maximum stress: 9675 psi

39. Worst Case Loading Results Maximum stress: 9675 psi

40. Margin Calculation • Margin for yield in the worst case loading scenario is negative. All others are positive • This is due to a high stress at the part surface. The net section stress will now be studied.

41. Worst Case Loading: Net Section Stress Average stress is calculated for the load path shown. New margins are calculated LoadPath

42. Net Section Margins • Net section margins are positive • The part is deemed to be safe for cleanroom usage

43. LabView Layout

44. Wire Diagram Each valve has 2 leads for a circuit. They will be connected to a terminal block and then to a terminal block on the AGT system

45. Bill of materials

46. Test plans

48. Our schedule for MSDII