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

Behavior of Sub-cooled Propellants in Room Temp.Fig: Liquid Nitrogen unloaded from a small a Dewar Flask to a bucket in a laboratory.

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

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).

Internal Structure of Cryo-Tracker Silicon diode sensors incorporated with the probe.Conductor Traces which constitute the rake of the temp- element

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.

Stratification of Sub-cooled Propellants The heat leak causes the propellant to warm and stratify due to natural buoyancy forces.

Cryo-Tracker Initially designed for incorporating in the propellant vessels of reusable launch vehicles.

Purpose of Cryo-TrackerFor knowing the amount of propellant loaded in.For knowing the liquid & ullage temperature.For knowing liquid level.

Mass Gauging MethodThe 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.

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.

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

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.

Advantages of Cryo-TrackerOperating CostsAccuracyReliabilitySafetyEfficiencyScalabilityFlexibility

Commercial ApplicationsCryogenic storage and transport tanksHome oxygen vessels Medevac helicopter and military field hospital oxygen-generating systemsAutomobiles running on liquid hydrogen or liqufied natural gas