Air Data Probe Self-Regulating Thin Film Heater
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Solution Overview
Problem
Air data probes using thin film heaters face excessive energy consumption and overheating as temperature increases above freezing due to the inherent characteristics of carbon nanotube (CNT) heaters, which lead to inefficient heating and potential heater failure.
Innovation Solution
The integration of a positive temperature coefficient (PTC) heating element, composed of a carbon black and polymer composite, in series with a negative temperature coefficient (NTC) heating element, made of a carbon nanotube and silicone composite, allows for efficient heating during freezing conditions and self-regulation at higher temperatures, preventing overheating and excessive power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a carbon nanotube (CNT) heater is used in an air data probe, then heating efficiency during freezing conditions is improved, but energy consumption increases excessively and overheating occurs as temperature rises above freezing
Solution Approach 1:
The patent combines two heating elements with opposite temperature coefficients: a PTC (positive temperature coefficient) element that increases resistance with temperature, and an NTC (negative temperature coefficient) CNT element that decreases resistance with temperature. This dual-element configuration dynamically adjusts the heating characteristics based on temperature conditions, achieving efficient freezing protection while preventing excessive energy consumption and overheating at higher temperatures.
2Temperature
If a carbon nanotube (CNT) heater is used in an air data probe, then heating efficiency during freezing conditions is improved, but overheating and potential heater failure occur as temperature rises above freezing
Solution Approach 1:
The patent combines two heating elements with opposite temperature coefficients: a PTC (positive temperature coefficient) element that increases resistance with temperature, and an NTC (negative temperature coefficient) CNT element that decreases resistance with temperature. This dual-element configuration dynamically adjusts the heating characteristics based on temperature conditions, achieving efficient freezing protection while preventing excessive energy consumption and overheating at higher temperatures.
Solution Approach 2:
The PTC element acts as a self-regulating component that provides negative feedback when temperature rises above freezing. As temperature increases, the PTC element's resistance increases, automatically reducing the current and power delivered to the heating system, thereby preventing overheating and heater failure without requiring external temperature sensors or control systems.
3Power
If conventional coil-based heating elements are used in an air data probe, then heating function is provided, but energy consumption is excessive compared to thin film heaters
Solution Approach 1:
The patent utilizes the unique temperature-dependent resistance characteristics of carbon nanotube materials. The NTC behavior of CNTs allows the heater to draw more current when cold (providing effective heating during freezing conditions) and automatically reduce current as temperature rises, achieving superior energy efficiency compared to conventional coil-based heaters with fixed resistance.
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
This combination reduces energy consumption by 20-25% compared to conventional coil-based heating elements, enhances safety by preventing heater failure, and allows for customized heating profiles without altering the external design of the air data probe.
Implementation Method 1
a positive temperature coefficient (PTC) heating element in series with a negative coefficient temperature (NTC) heating element
Implementation Method 2
a negative coefficient temperature (NTC) heating element
Implementation Method 3
Heating elements, such as resistive heating elements or thin film heaters, for example, are typically implemented within the housing of the probe to prevent icing during freezing conditions
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
An air data probe (10) includes a strut assembly (16) extending from a base (14), and a tube assembly (18) coupled to the strut assembly (16). One or both of the strut assembly (16) and the tube assembly (18) comprises a self-regulating thin film heating arrangement (32, 33). The self-regulating thin film heating arrangement (32, 33) includes at least one circuit including a positive temperature coefficient (PTC) heating element connected in series with a negative temperature coefficient (NTC) heating element.