Aircraft Drain/Fill Fitting With Heat Transfer Probe Against Freezing
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Solution Overview
Problem
Aircraft drain/fill fittings face inefficiencies in preventing ice buildup due to coaxial heaters prone to electrical shorts and surface heaters being ineffective when mounted against metal surfaces, leading to rapid freezing of liquids at high altitudes.
Innovation Solution
A drain/fill fitting design featuring a housing with a coaxial or annular first and second segment, where a heater in the first segment applies heat and an elongate heat transfer probe made of high thermal transfer coefficient materials, such as aluminum, copper, or graphene, extends into the second segment to prevent freezing, maintaining heat transfer efficiency without direct contact with the cold exterior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If surface heaters are mounted against metal surfaces, then heating is provided to prevent ice buildup, but the metal surface acts as a heat sink that removes heat faster than it can be supplied, rendering the heater ineffective
Solution Approach 1:
The patent introduces an elongate heat transfer probe as an intermediary component that extends from the heated interior housing segment into the exterior housing segment. This probe acts as a thermal bridge, conducting heat from the interior to the exterior portion where ice formation occurs, thereby overcoming the heat sink effect of the metal surface and delivering heat directly to the critical area.
Solution Approach 2:
The invention transitions from surface-level heating (two-dimensional contact with the metal surface) to volumetric heat transfer through the probe. By extending the heat transfer path into the third dimension (from interior to exterior housing segments), the system delivers heat to the exterior portion without relying on surface contact, thus avoiding the heat sink problem.
2Loss of energy
If the exterior housing portion remains cold to maintain thermal isolation, then thermal efficiency is improved, but liquid in the fitting freezes quickly
Solution Approach 1:
The elongate heat transfer probe acts as a controlled thermal intermediary that selectively transfers heat to the exterior housing segment and liquid flow path without compromising the overall thermal isolation of the fitting. By positioning the probe to extend into the exterior portion, heat is delivered precisely where needed (at the liquid interface) while minimizing heat loss to the external environment.
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 reduces the incidence of freezing in the exterior segment by efficiently transferring heat from the interior to the exterior, ensuring the drain/fill fitting remains operational in below-freezing conditions without interfering with existing electrical systems or fitting operations.
Implementation Method 1
A heater applies heat to the first housing segment
Implementation Method 2
an elongate heat transfer probe is positioned in heat transfer contact with the first housing segment and extends into the second housing segment
Data Source
AI summary
An aircraft drain/fill fitting includes a housing adapted for being fitted into an opening between an aircraft interior and an aircraft exterior. The housing has an interior housing segment fluidly coaxially communicating with an exterior housing segment to define a liquid flow path therethrough, and a heater for applying heat to the interior housing segment. A hollow insert element is positioned in the interior housing segment in heat transfer contact with an inner wall of the interior housing segment. An elongate heat transfer probe is positioned in heat transfer contact with the hollow insert element and extends into the exterior housing segment to reduce the incidence of freezing of liquid in the exterior housing segment.