MidPoint Review Report

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• Mid-Point Review Report
• 900 MHz NMR Probe Cryogenic Gas Supply System
• Team 2
• Rebecca Altman
• Jason Kitchen
• Zachary Stevenson
• Jessica Vanterpool
• February 26th, 2009

2
Presentation Outline

• Subsystem Testing
• Temperature Variance
• Mass Flow Controller

• Pneumatic Actuator vs. Solenoid Valve
• Future Testing
• Future Plans

Team with Dr. Brey in front of 900 MHz magnet
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Project Overview
4
Assembly Progress

• Refill controller
• All wires have been sauntered and connected
• Both alarms have been added
• Two pin connector for the solenoid valve has been
  added

Senior Design Group 2 900 MHz NMR Probe
Cryogenic Gas Supply System
5
Heat Exchanger Coil Testing

• Increased the flow rate in increments of 5 scfh
• 10 Minute Intervals
• Ideal Flow Rate is 60 scfh
• Very high pressure readings before 40 scfh
  (debris)
• Droplets at 65 scfh, temperature at 78.1 K
• Results
• Experimentally T 84.7 K (With possible
  debris)
• Theoretically T 79.3 K (Did not take debris
  into consideration)
• Within required range, perform experiment again
  for verification

Senior Design Group 2 900 MHz NMR Probe
Cryogenic Gas Supply System
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Heat Exchanger Coil Testing Cont.

• Flow Rate and Pressure vs. Temperature

Senior Design Group 2 900 MHz NMR Probe
Cryogenic Gas Supply System
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Heat Exchanger Coil Testing Cont.

• Equipment and Schematic Video

Senior Design Group 2 900 MHz NMR Probe
Cryogenic Gas Supply System
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N2 Gas Flow Regulation Improvement

• Current valve block in spectrometer has 15 valve
  setting combinations for N2 gas flow from 0 to
  2000 L/hr
• Problem gas flow fluctuates with supply
  pressure changes, which leads to temperature
  fluctuation
• Solution purchased a mass flow controller from
  Alicat Scientific, cost 1396.00

• Features
• Flow range is 0 to 50 L/min
• Self adjusts for pressure changes using solenoid
  valve
• Typical 100 ms response time
• Accuracy 0.8 of reading
• Repeatability 0.2
• 30 pre-defined gases, including N2

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Testing Progress

• Nitrogen Dewar
• Temperature variance test
• Several refills were carried out at three
  different cryostat pressures (6,10,22 psig)
• First the FTS system was set at -75 C
• The N2 gas flow was set to 25 scfh during each
  refill
• Temperature was also allowed to reach a steady
  state before each refill began
• Digital thermometer used to record temperature
  reading at transfer line entrance

Liquid valve
Gas Valve
Senior Design Group 2 900 MHz NMR Probe
Cryogenic Gas Supply System
10
Testing Progress Cont.

• Results
• Less boil off at 6 psig, however there was a
  significant decrease in the refill rate and twice
  had to open the supply valve further to continue
  the refill
• Pressure will have to be maintained to ensure a
  good refill rate
• lower supply cryostat pressures will lower the
  effect of a refill on the output temp to the
  probe
• Significant decrease in the amount of N2 vapor
  venting out of the HX each time the supply
  pressure was lowered

Senior Design Group 2 900 MHz NMR Probe
Cryogenic Gas Supply System
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Solution Pneumatically Actuated Cryogenic Valve

• Solenoid valve moved 15 m from magnet axis,
  outside of magnetic field
• Solenoid now controls a pilot gas connected to
  pneumatic valve actuator
• Pneumatic valve can be located inside magnetic
  field
• Pneumatic actuation opens LN2 fill line to refill
  from supply dewar to HX cryostat

12
Purchase Summary

• Waiting for quotation from Burkert Fluid Controls
  for pneumatically actuated cryogenic valve
• Remaining purchases will be plumbing fittings for
  hookup of valves to supply Dewar and HX cryostat

13
Design Problem Refill Solenoid Valve Proximity
to Magnet

• LN2 supply dewar must be within 3 m of the 900
  MHz magnets axis
• Refill solenoid located here could eventually
  fail as it becomes permanently magnetized

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Future Testing

• March 3rd Refill Controller Test 1
• Check Wire Diagrams
• Refill Controller will be connected to the supply
  system where each switch will be test multiple
  times
• March 5th Hx Coil Test 2
• Mass Flow Controller instead of Wall Pressure
  Regulator
• Spring Break Dr. Fus Experiment
• Dr. Fu will be using our setup minus the
  controller.
• Will be given data from him after Spring Break

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Future Plans

• Nitrogen Dewar
• Come up with a test that will be able to bypass
  or insulate the HX pre-cooling coils to see what
  effect they have on the refill temp stability
• Temperature Fluctuation Issues
• Talk with Dr. Van Sciver
• Temperature Fluctuation from the Supply Dewar
• Temperature readings taken at the outlet, better
  place?
• Things that can be done to prevent further
  temperature flunctuation

Senior Design Group 2 900 MHz NMR Probe
Cryogenic Gas Supply System
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Questions?