Ion Propulsion Propellant Transfer Estimation

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing ion propulsion systems inaccurately estimate propellant transfer between tanks due to lack of real-time updates in pressure and temperature profiles during the transfer process, leading to inaccuracies in flow rate and mass calculations.

Innovation Solution

A method and system that continuously calculate and update the flow rate of propellant through a latch valve based on initial and intermediate pressure and temperature readings, using a computing device to implement a flow equation and polytropic processes to determine mass transfer and pressure equalization, with built-in xenon properties tables for accurate real-time estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If propellant transfer estimation is performed using initial pressure and temperature readings only, then the calculation process is simple and fast, but the measurement precision deteriorates due to temperature and pressure changes during transfer

Engineering Contradiction:
Improvepropellant transfer estimation accuracyVSAvoidcalculation process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system transitions from static initial readings to dynamic continuous monitoring of pressure and temperature during the entire propellant transfer process. Sensors continuously capture state changes, and the calculation system dynamically updates flow rate and mass estimates in real-time, ensuring accuracy despite changing conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements feedback by continuously monitoring pressure and temperature during transfer and using these updated readings to recalculate propellant mass and flow rate. This closed-loop approach allows the system to adjust estimates based on actual state changes, significantly improving measurement precision.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If real-time updates of pressure and temperature profiles are implemented during propellant transfer, then measurement precision improves, but the loss of time increases due to continuous calculations

Engineering Contradiction:
Improvepropellant transfer estimation accuracyVSAvoidtransfer process time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system maintains continuous monitoring and calculation throughout the propellant transfer process without interruption. Pressure and temperature sensors continuously capture data, and the calculation system continuously updates estimates, ensuring that useful measurement action occurs throughout the entire transfer duration rather than only at discrete points.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system performs calculations at periodic intervals during the transfer process, updating pressure and temperature readings at regular time steps. This periodic approach balances the need for accurate real-time estimation with computational efficiency, preventing excessive time loss while maintaining precision.

Inventive Principle:
Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate, real-time estimation of propellant transfer, preventing phase transition and ensuring accurate measurement by maintaining propellant in a gaseous state, thus extending operational life and precision in ion propulsion systems.

Implementation Method 1

The flow rate is calculated based on an initial pressure and an initial temperature of each of the first tank and the second tank for a beginning of the transfer event and on a determined intermediate pressure for each of the first tank and the second tank for an intermediate time before an end of the transfer event

Methodology Applied
Scientific EffectIdeal gas law:

Implementation Method 2

using a computing device to implement a flow equation and polytropic processes to determine mass transfer and pressure equalization

Methodology Applied
Scientific EffectPolytropic process:

Data Source

PatentEP2873622B1Methods and systems for estimation of propellant transfer in an ion propulsion system
Publication Date: 2018.08.22 THE BOEING CO
  • EP2873622B1 patent drawingFigure 1
  • EP2873622B1 patent drawingFigure 2
  • EP2873622B1 patent drawingFigure 3

AI summary

Methods and systems for estimating propellant transfer in an ion propulsion system (200) are disclosed. One example is a method for estimating transfer of a propellant between a first tank (208) and a second tank (210) in an ion propulsion system during a transfer event. The first tank and the second tank are separated by a valve (216). A flow rate of the propellant through the valve is calculated based on an initial pressure and an initial temperature of each of the first tank and the second tank for a beginning of the transfer event, calculating, based at least in part on the flow rate, a mass of propellant transferred through the latch over a period of time ending at an intermediate time before an end of the transfer event, and determining an intermediate pressure and temperature for each of the first tank and the second tank for the intermediate time.