Nanodiamond Nanofluids for Enhanced Thermal Conductivity

Abstract

Deaggregation of oxidized ultradispersed diamond (UDD) in dimethylsulfoxide followed by reaction with glycidol monomer, purification via aqueous dialysis, and dispersion in ethylene glycol (EG) base fluid affords nanodiamond (ND)-poly(glycidol) polymer brush:EG nanofluids exhibiting 12% thermal conductivity enhancement at a ND loading of 0.9 vol %. Deaggregation of UDD in the presence of oleic acid/octane followed by dispersion in light mineral oil and evaporative removal of octane gives ND·oleic acid:mineral oil dispersions exhibiting 11% thermal conductivity enhancement at a ND loading of 1.9 vol %. Average particle sizes of ND additives, determined by dynamic light scattering, are, respectively, ca. 11 nm (in H2O) and 18 nm (in toluene). Observed thermal conductivity enhancements outperform enhancement effects calculated using Maxwell's effective medium approximation by 2- to 4-fold. Covalent ND surface modification gives 2-fold greater thermal conductivity enhancement than ND surface modification via hydrogen-bonding interactions at similar concentrations. Stable, static ND:mineral oil dispersions are reported for the first time.

Strong enhancement in thermal conductivity of ethylene glycol-based nanofluids by amorphous and crystalline Al2O3 nanoparticles

“…[1][2][3][4][5][6][7][8][9]19 Such increment in the heat transport characteristics of base fluids suggests the crucial benefits which give credence to liquid coolants for moving heat away from electronic, optical, machinery, or nuclear reactor systems. [5][6][7]9 Various nanoparticles (NPs) of metals and metal oxides have been added to EG for enhancing the thermal conductivity (TC) of base fluid and are potentially used in heat transfer system.…”

“…[5][6][7]9 Various nanoparticles (NPs) of metals and metal oxides have been added to EG for enhancing the thermal conductivity (TC) of base fluid and are potentially used in heat transfer system. 2,[5][6][7][8][9]19,21,[23][24][25] The nanofluids based on EG reveal a higher TC having nonlinear relationship with temperature. 23,29 A very recent report to examine the effects of nanoparticle size and temperature has been published focusing on the TC enhancement of water-based Al 2 O 3 nanfluids.…”

“…The high-resolution micrographs in real and reciprocal space were acquired with a HR-TEM (FEI Tecnai G2 F30 STWIN) operated at 300 kV accelerating voltage. Al 2 (model TPS-500) was employed in this study to measure the TC of the corresponding nanofluids within the temperature range of 0-100 C. We present the crystallographic structural characteristics and electron microscopy of the synthesized a-Al 2 O 3 NPs in Figures 1(a)-1(f). The XRD patterns and morphological details of all three phases (a-, c-, and a-Al 2 O 3 ) have been discussed in our earlier report.…”

“…Strong enhancement in thermal conductivity of ethylene glycol-based nanofluids by amorphous and crystalline Al 2 …”

“…2,6,26 Since nano-amorphous particle is more open structure than nanocrystalline material, in which individually atoms are randomly distributed may form long-range thermal transfer channels, it is clear that particles with different crystallinity influence heat transfer differently, as schematically depicted in Figure 3. The long-range order in nano-crystalline may resist to the liquid-particle interface and resulted in the lower enhanced TC of the crystalline c-and a-Al 2 O 3 /EG nanofluids.…”