CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Indian Patent Application No. 201811034572 filed Sep. 13, 2018, which is incorporated herein by reference in its entirety.

BACKGROUND

The following description relates to aircraft wing ice protection and, more specifically, to a hybrid heater for aircraft wing ice protection.

Aircraft wing ice protection systems use various heater technologies for anti-icing or de-icing. Of these various heater technologies, one employs carbon nanotubes (CNTs) for electro-thermal heating. Where CNTs are employed in electro-thermal heating applications, it has been found that, at a certain volume percentage of CNTs in a CNT/silicone nanocomposite, a negative temperature coefficient (NTC) of the nanocomposite is mitigated and a resistance thereof stabilizes at higher temperatures.

BRIEF DESCRIPTION

According to an aspect of the disclosure, a hybrid heater system for aircraft wing ice protection is provided. The hybrid heater system includes a voltage source, a carbon nano-tube (CNT) heater, a first positive temperature coefficient (PTC) heater disposed in parallel with the CNT heater to form a parallel formation and a second PTC heater disposed in series between the voltage source and the parallel formation.

In accordance with additional or alternative embodiments, the second PTC heater establishes a maximum temperature capability for ice protection and the hybrid heater system operates with an absence of active temperature controls.

In accordance with additional or alternative embodiments, the first and second PTC heaters have differing and tailored electrical resistivity.

In accordance with additional or alternative embodiments, an effective electrical resistance of the parallel formation is less than an electrical resistance of each of the CNT heater and the first PTC heater.

In accordance with additional or alternative embodiments, the CNT heater and the first and second PTC heaters are layered in an aircraft wing.

In accordance with additional or alternative embodiments, the CNT heater and the first PTC heater occupy a same layer in the aircraft wing and the same layer occupied by the CNT heater and the first PTC heater includes a first terminal, a second terminal, first PTC heater elements extending between the first and second terminals and CNT heater elements interleaved between the first PTC heater elements and extending between the first and second terminals.

In accordance with additional or alternative embodiments, the aircraft wing includes an outermost wing surface, a first fiber glass prepreg layer underlying the outermost wing surface and a first film adhesive, a first heater layer underlying the first fiber glass prepreg layer and a second film adhesive, the first heater layer comprising CNT heater elements of the CNT heater and first PTC heater elements of the first PTC heater, a second heater layer underlying the first heater layer and a third film adhesive, the second heater layer comprising the second PTC heater and a second fiber glass prepreg layer underlying the second heater layer and a fourth film adhesive.

In accordance with additional or alternative embodiments, the CNT heater and the first PTC heater occupy different layers in the aircraft wing.

In accordance with additional or alternative embodiments, the aircraft wing includes an outermost wing surface, a first fiber glass prepreg layer underlying the outermost wing surface and a first film adhesive, a first heater layer underlying the first fiber glass prepreg layer and a second film adhesive, the first heater layer comprising the CNT heater, a second heater layer underlying the first heater layer and a third film adhesive, the second heater layer comprising one of the first or second PTC heaters, a third heater layer underlying the second heater layer and a fourth film adhesive, the third heater layer comprising the other of the first or second PTC heaters and a second fiber glass prepreg layer underlying the third heater layer and a fifth film adhesive.

According to an aspect of the disclosure, a hybrid heater system for ice protection of an aircraft wing is provided. The hybrid heater system includes a voltage source, a carbon nano-tube (CNT) heater comprising CNT heater elements and a first positive temperature coefficient (PTC) heater disposed in parallel with the CNT heater to form a parallel formation. The first PTC heater includes first PTC heater elements interleaved with the CNT heater elements in a first aircraft wing layer and a second PTC heater disposed in a second aircraft wing layer and in series between the voltage source and the parallel formation.

In accordance with additional or alternative embodiments, the second PTC heater establishes a maximum temperature capability for ice protection and the hybrid heater system operates with an absence of active temperature controls.

In accordance with additional or alternative embodiments, the first and second PTC heaters have differing tailorable electrical resistivity.

In accordance with additional or alternative embodiments, an effective electrical resistance of the parallel formation is less than an electrical resistance of each of the CNT heater and the first PTC heater.

In accordance with additional or alternative embodiments, the first aircraft wing layer includes first and second terminals between which the interleaved CNT and first PTC heater elements extend.

In accordance with additional or alternative embodiments, the second aircraft wing layer underlies the first aircraft wing layer.

According to an aspect of the disclosure, a hybrid heater system for ice protection of an aircraft wing is provided. The hybrid heater system includes a voltage source, a carbon nano-tube (CNT) heater in a first aircraft wing layer, a first positive temperature coefficient (PTC) heater disposed in one of a second or a third aircraft wing layer and in parallel with the CNT heater to form a parallel formation and a second PTC heater disposed in the other of the second or the third aircraft wing layer and in series between the voltage source and the parallel formation.

In accordance with additional or alternative embodiments, the second PTC heater establishes a maximum temperature capability for ice protection and the hybrid heater system operates with an absence of active temperature controls.

In accordance with additional or alternative embodiments, the first and second PTC heaters have differing tailorable electrical resistivity.

In accordance with additional or alternative embodiments, an effective electrical resistance of the parallel formation is less than an electrical resistance of each of the CNT heater and the first PTC heater.

In accordance with additional or alternative embodiments, the third aircraft wing layer underlies the second aircraft wing layer and the second aircraft wing layer underlies the first aircraft wing layer.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

