Hard Carbon Nanotube Sponges for Highly Efficient Cooling via Moisture Absorption–Desorption Process

Abstract

Heat dissipation is a serious limitation for increasingly miniaturized and functionalized electronics, resulting in the continuous need for developing highly efficient cooling methods. Here, utilizing the strong van der Waals force between super-aligned carbon nanotubes (SACNTs), a self-supported three-dimensional (3D) CNT/ CaCl 2 radiator with a more outstanding cooling performance than Al cooling fins was designed. Unlike the soft CNT sponges, these 3D structures could sustain a high pressure of 4.5 MPa with a small compression of 10% and thus are defined as hard CNT sponges. Hard CNT sponges show a 44.3% higher cooling efficiency than commercial Al cooling fins at a humidity of 50% due to the massive latent heat of water combining with the high thermal conductivity of CNTs and the high emissivity of the composites. The self-adjusting moisture absorption−desorption process could dissipate heat by water evaporation when electronics work at high power and spontaneously absorb moisture to regenerate the sponges at the standby mode of electronics. Besides, hard CNT sponges possess a much lower density (0.98−1.70 g cm −3 ) than aluminum (2.7 g cm −3 ). This high-performance cooler provides an alternative thermal management method for electronics.

Atmospheric Hygroscopic Ionogels with Dynamically Stable Cooling Interfaces Enable a Durable Thermoelectric Performance Enhancement

“…Benefited from their excellent hygroscopicity and intrinsic swellable property, these resultant RIG samples achieved rapid and high‐capacity moisture uptakes of 0.59, 0.28, 0.14 g cm −2 at 90%, 70%, and 50% RH, respectively, within 12 h (Figures S7 and S8, Supporting Information). Notably, these actual moisture sorption amounts of RIG were superior to most of reported evaporative‐cooling systems in a wide range of humidity, [ 9,16,17,19,33,34 ] thus showing a great promise in evaporative cooling (Table S1, Supporting Information). In addition, desorption rates of absorbed water are crucial factors for heat removal, which mainly depended on heat source temperatures.…”

Solid–Liquid–Vapor Triphase Gel

“…Both the hydrogel and the aerohydrogel possess a large amount of water in the system (Figure a), which enables them to serve as the evaporative cooling materials using enormous latent heat for the liquid–vapor phase change transition of water (up to 2.257 kJ·kg –1 at 0.1 MPa, 20 °C). − As shown in Figure a, the water content of the aerohydrogel (with the SSAM content of 10 wt %) is slightly lower than that in the hydrogel of the same weight. When placed under the same condition (80 °C), the average evaporation rate of water in the aerohydrogel is considerably higher than that in the PVA hydrogel, which can be attributed to rich LV interfaces for water evaporation and continuous air channels for vapor transport in the aerohydrogel.…”

Numerical simulation of unsteady ethylene glycol/CNTs micropolar nanofluid flow through a squeezing channel: An approach to industrial applications

“…From this, one can observe that the present results are very much agreeing with Gupta and Saha. 42 T A B L E 5 Numerical values of skin friction and Nusselt number for MWCNT-EG nanofluid when S q = 1, R = 0.01, Ha = 2, s 1 = 0.2, Pr = 0.7, Ec = 0.1, δ = 0.01, and ϕ = 3%…”