Novel fibrillar carbon nanotube heat transfer gels with enhanced thermal conductivities
type: CreativeWork
description: Lubricants and cooling agents such as oil, ethylene glycol, and water are often used as traditional heat transfer fluids (HTFs) in engines, radiators, heat pumps, and other equipment which require cooling and/or energy maintenance. The United States of America (USA) spends over $80 billion on energy maintenance and increasing the thermal efficiency of HTFs by 25% could annually save over $20 billion. This study was aimed at improving the thermal conductivity (TC) of synthetic and vegetable oil heat transfer fluids (HTFs) by using Single-Walled Carbon Nanotubes (SWNTs) additives that resulted in a semi-solid lubricant that was a nanotube-HTF (n-HTF). The n-HTFs were processed with nitrogen containing additives that coupled with toluene and acetone solvent processing promoted the gelation of the carbon nanotube fibers in the oil. Such processing improved the nanotube dispersion due to hydrogen bonding (H bonding) and micelle formation of the amine groups around the carbon nanotube rod-like fibers and the additive-oil matrix. This allowed for high weight percent (Wt %) loadings of carbon nanotubes in the oil. Characterization via thermal graviometric analysis (TGA) and Fourier Infrared Transform (FTIR) showed that high temperature radical mechanisms breakdown both the oil and nanotubes, and optical microscopy showed that sonication-homogenizing-mixing affects the coagulation-flocculation-aggregation-agglomeration of the nanotubes. Additionally we used two new TC instruments, the Mathis-Hot Disk and KD2 systems, to provide accurate and reproducible data with a 10% and 4% error margin for the Mathis and KD2, respectively. Raman and FTIR spectroscopies suggest that the TC enhancements result from SWNT phonon mechanisms, these being phonon-phonon, phonon-defect, and phonon-interface, all of which are present at room temperature with the absence of ballistic and superconductivity phenomena. Additional vibrations in the oil that occur due to Brownian motion and electron-phon…
abstract: Lubricants and cooling agents such as oil, ethylene glycol, and water are often used as traditional heat transfer fluids (HTFs) in engines, radiators, heat pumps, and other equipment which require cooling and/or energy maintenance. The United States of America (USA) spends over $80 billion on energy maintenance and increasing the thermal efficiency of HTFs by 25% could annually save over $20 billion. This study was aimed at improving the thermal conductivity (TC) of synthetic and vegetable oil heat transfer fluids (HTFs) by using Single-Walled Carbon Nanotubes (SWNTs) additives that resulted in a semi-solid lubricant that was a nanotube-HTF (n-HTF). The n-HTFs were processed with nitrogen containing additives that coupled with toluene and acetone solvent processing promoted the gelation of the carbon nanotube fibers in the oil. Such processing improved the nanotube dispersion due to hydrogen bonding (H bonding) and micelle formation of the amine groups around the carbon nanotube rod-like fibers and the additive-oil matrix. This allowed for high weight percent (Wt %) loadings of carbon nanotubes in the oil. Characterization via thermal graviometric analysis (TGA) and Fourier Infrared Transform (FTIR) showed that high temperature radical mechanisms breakdown both the oil and nanotubes, and optical microscopy showed that sonication-homogenizing-mixing affects the coagulation-flocculation-aggregation-agglomeration of the nanotubes. Additionally we used two new TC instruments, the Mathis-Hot Disk and KD2 systems, to provide accurate and reproducible data with a 10% and 4% error margin for the Mathis and KD2, respectively. Raman and FTIR spectroscopies suggest that the TC enhancements result from SWNT phonon mechanisms, these being phonon-phonon, phonon-defect, and phonon-interface, all of which are present at room temperature with the absence of ballistic and superconductivity phenomena. Additional vibrations in the oil that occur due to Brownian motion and electron-phon…
author: Rostro, Betty Catalina
language: eng
keywords: Engineering, Materials science
date published: 2007
date modified: 2026-07-24T04:10:28Z
provider: Rice University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Rice University

PropertyValue
property ID: Handle
value: https://hdl.handle.net/1911/20534