The stable and homogeneneous aqueous suspension of carbon nanotubes was prepared in this study. The stability of the nanofluids was improved greatly due to the use of a new dispersant, humic acid. The thermal conductivity of the aqueous suspension was measured with the 3ω method. The experimental results showed that the thermal conductivity of the suspensions increases with the temperature and also is nearly proportional to the loading of the nanoparticles. The thermal conductivity enhancement of single-walled carbon nanotubes (SWNTs) suspensions is better than that of the multi-walled carbon nanotubes (MWNTs) suspensions. Especially for a volume fraction of 0.3846% SWNTs, the thermal conductivity is enhanced by 40.5%. Furthermore, the results at 30°C match well with Jang and Choi’s model.

In this paper, the influences of different conditions on heat-transfer stability of porous fibrous composition were analyzed by the one-dimensional unsteady heat transfer model. It was resulted that the surface condition of composition was key parameter for heat performance during different thermal process. Great humidity and thermal difference caused the heat transfer fluctuating of material covering, and then changed the thermal conductivity. For the insulation materials under low temperature, the heat performance was sharply fluctuated nearby 0°C.