Our Method

Thermal Gauging Method (TGM) of propellant estimation is based on a concept of measuring the thermal capacitance of a tank containing liquid fuel and pressurant gas by measuring the thermal response of the propellant tank to heating and comparing the observed temperature rise to simulation results obtained from a tank thermal model. The TGM employs a very sophisticated thermal model of the propellant tank which takes into account fuel distribution in the tank, temperature gradients in the tank, etc. The tank temperature rise can be induced by different means like tank heaters, equipment heaters (e.g. IRU unit on BSS 601), Sun load. The biggest advantage of the thermal gauging method over other methods is improving of the TGM accuracy as propellant load is getting lower due to increase temperature rise sensitivity to load change when tank load is decreasing.

Tank temperature rise during TGM operation
(bi-propellant satellite)

Comparison of TGM with other gauging methods:

Accuracy of Bookkeeping and PTV methods decreases with the mission life.
TGM offers high accuracy when it matters most - at the end of mission life.

Information required
to conduct estimation:

Simplified spacecraft design
Tank temperature telemetry
Means of increasing tank temperature

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