Ceramic Coated Heated Fuel Filter for Ice Clogging

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Solution Overview

Problem

Aircraft gas turbine engine fuel systems face ice clogging issues due to varying environmental temperatures, with conventional filters either causing significant fluid pressure drops when preventing small ice debris or failing to catch debris effectively, particularly in auxiliary power units that are prone to icing during rest periods.

Innovation Solution

A fuel filter comprising a resistively heated filter screen with a thermally conductive, electrically insulating ceramic coating in a hydrodynamic filtering pattern, which minimizes pressure drop while effectively melting ice debris and preventing clogging by distributing heat evenly across the filter screen.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the filter aperture is made narrow to prevent small ice debris ingress, then ice protection is improved, but fluid pressure drop increases significantly

Engineering Contradiction:

Improveice protectionVSAvoidfluid pressure drop

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The heating element is activated before fuel flow to melt accumulated ice on the filter screen, preventing ice debris from blocking the filter apertures. This preliminary action maintains aperture openness and reduces pressure drop while preserving ice protection capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The filter screen temperature is changed from cold to heated state through electrical heating, altering the physical state of ice deposits and converting them from solid blocking debris to liquid that passes through the filter. This parameter change resolves the contradiction between ice protection and pressure drop

Inventive Principle:

Principle #35Parameter changes

2Stress or pressure

If the filter aperture is made wide to reduce fluid pressure drop, then fluid flow is improved, but ice debris filtration capability deteriorates

Engineering Contradiction:

Improvefluid pressure dropVSAvoidice debris filtration

Core Design Contradiction:

Stress or pressureVSReliability

Solution Approach 1:

The mechanical filtration system is supplemented with a thermal field system (heating element). Instead of relying solely on mechanical aperture sizing, the patent uses thermal energy to melt ice, replacing the need for narrow mechanical filters and thereby reducing pressure drop while maintaining filtration effectiveness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Thermal energy acts as an intermediary between the heating element and ice debris, melting the ice into water that can pass through wider apertures. This intermediary mechanism allows wider filters to maintain ice protection capability without increasing pressure drop

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If heating is applied to melt ice on the filter screen, then ice removal is improved, but risk of electrical discharge in fuel environment increases

Engineering Contradiction:

Improveice removalVSAvoidelectrical discharge risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A ceramic coating layer serves as an intermediary between the heating element and the fuel environment. This coating provides electrical insulation to prevent discharge into the fuel while maintaining thermal conduction to enable ice melting, thus resolving the contradiction between ice removal and electrical safety

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The filter structure uses a composite material system combining heating element, ceramic coating, and filter screen. The ceramic coating specifically addresses the electrical discharge risk by providing both thermal and electrical property differentiation, allowing safe heating operation in the explosive fuel environment

Inventive Principle:

Principle #40Composite materials

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

The solution effectively prevents ice accumulation and clogging in fuel systems by maintaining efficient fluid flow and reducing pressure drops, ensuring reliable operation of gas turbine engines across a wide temperature range.

Implementation Method 1

The heating element is disposed within the first hollow member

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The coating is formed of a thermally conductive, electrically insulating ceramic

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10954860B2Ceramic coating for heated fuel filter

Publication Date: 2021.03.23 RTX CORP

AI summary

A fuel filter comprises a filter screen, a heating element, and a coating. The filter screen includes a first hollow member. The heating element is disposed within the first hollow member. The coating is formed of a thermally conductive, electrically insulating ceramic in a hydrodynamic filtering pattern surrounding the filter screen but having a different shape than a shape of the hollow member.