Cryo-Tracker Level, Temperature, and Mass Gauging Fluid Sensors

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Cryo-Tracker Level, Temperature,and Mass
Gauging Fluid Sensors
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Behavior of Sub-cooled Propellants in Room Temp.

• Fig Liquid Nitrogen unloaded from a small a
  Dewar Flask to a bucket in a laboratory.

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Dewar Flask

• Fig A 25 l liquid nitrogen laboratory Dewar
  flask.
• Inner wall linings are silvered to reduce heat
  leakage.

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Flexible Sensing Probe

• Probe is made of series of polyimide layers of
  thickness 0.0254 mm.
• Rakes made of stainless steel tubing, wire, and
  phenolic insulators weigh (6.70 g/cm).

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Internal Structure of Cryo-Tracker

• Silicon diode sensors incorporated with the
  probe.
• Conductor Traces which constitute the rake of the
  temp- element

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Installed Cryo-Tracker Probe

• Cryo-Tracker probe 60 ft. long.
• 2.5 cm wide.
• containing 26 silicon diode sensors.
• Its weight is less than 0.59 kg.

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Stratification of Sub-cooled Propellants

• The heat leak causes the propellant to warm and
  stratify due to natural buoyancy forces.

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Cryo-Tracker

• Initially designed for incorporating in the
  propellant vessels of reusable launch vehicles.

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Purpose of Cryo-Tracker

• For knowing the amount of propellant loaded in.
• For knowing the liquid ullage temperature.
• For knowing liquid level.

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Mass Gauging Method

• The entire liquid and ullage temperature profile
  is first obtained.
• Tank pressure can then be used to calculate a
  liquid density profile.
• Liquid density profile is integrated over the
  known tank volume.

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Dual-Purpose Probe.

• Temperature measured using silicon diode
  sensors.
• Liquid level detection accuracy is a function of
  the sensor spacing.
• For 12 inch sensor spacing, the overall liquid
  level accuracy is 6 inches.

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Performance

• Consistent thermal response can be
• seen between the sensing elements in
• a dual-element probe when its thermal-cycled
  in liquid nitrogen.

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Hot-Fire Test (anomaly condition)

• The probe is also capable of measuring
  transient fluid temperature changes.
• Figure Tracking the rapid change in liquid
  oxygen temperature when warm gases injected
  into the tank mixed the contents.

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Advantages of Cryo-Tracker

• Operating Costs
• Accuracy
• Reliability
• Safety
• Efficiency
• Scalability
• Flexibility

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Commercial Applications

• Cryogenic storage and transport tanks
• Home oxygen vessels
• Medevac helicopter and military field hospital
  oxygen-generating systems
• Automobiles running on liquid hydrogen or
  liqufied natural gas