Thermal management of thermoacoustic sound projectors using a free-standing carbon nanotube aerogel sheet as a heat source

Abstract

Carbon nanotube (CNT) aerogel sheets produce smooth-spectra sound over a wide frequency range (1-10(5) Hz) by means of thermoacoustic (TA) sound generation. Protective encapsulation of CNT sheets in inert gases between rigid vibrating plates provides resonant features for the TA sound projector and attractive performance at needed low frequencies. Energy conversion efficiencies in air of 2% and 10% underwater, which can be enhanced by further increasing the modulation temperature. Using a developed method for accurate temperature measurements for the thin aerogel CNT sheets, heat dissipation processes, failure mechanisms, and associated power densities are investigated for encapsulated multilayered CNT TA heaters and related to the thermal diffusivity distance when sheet layers are separated. Resulting thermal management methods for high applied power are discussed and deployed to construct efficient and tunable underwater sound projector for operation at relatively low frequencies, 10 Hz-10 kHz. The optimal design of these TA projectors for high-power SONAR arrays is discussed.

Aligned Carbon Nanotube Film Enables Thermally Induced State Transformations in Layered Polymeric Materials

“…4 This can be achieved using microheater films. Using nanoscale elements, such as carbon nanotubes (CNTs), [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] graphene, 10,[20][21][22][23] metal nanowires (NWs), 19,[24][25][26][27][28][29][30][31] or hybrids of thereof, 24,32 recent work has shown that microheater films with high operating temperatures and fast thermal ramp rates can be made. However, the lack of CNT/graphene/NW alignment in these microheater films compromises their mechanical properties and electrical stability, 32 making them less suitable for application in structures that may be exposed to stress, such as airplane wings.…”

Investigation of electromagnetic properties of MWCNT aerogels produced via catalytic ethylene decomposition

“…MWCNT aerogels can also be considered as a disordered metamaterial based on carbon nanotubes. In particular, the interaction of MWCNT aerogels with an electromagnetic field in the microwave and THz regions was recognized to be of great interest . In order to obtain MWCNT aerogel‐based materials with tailored characteristics, one should consider the properties of a single aerogel particle.…”

Coupling and confinement of current in thermoacoustic phased arrays

“…The source is nonresonant, broadband, and, for single-drive frequencies, has high fidelity (13,14). Hence, arrays of these sources (15)(16)(17) could offer considerable advantages for many array-based technologies, if phase control of individual elements could be realized. Of particular note is that the elements only act as sources, not receivers: Coupled with the fact that the production mechanism involves no mechanical movement of the source, this transcends issues associated with speaker-microphone cross-talk (18).…”