Kin Yuen Leong

Thermal Conductivity of Carbon Nanotube Based Nanofluids as Heat Transfer Fluids

Conventional heat transfer fluids such as water and ethylene glycol exhibit low thermal conductivity. These fluids have certain influences on the efficiency of the thermal system. Efficiency of the thermal system is dependent on the thermal conductivity of the heat transfer fluid. New generation of heat transfer fluid such as nanofluid has potential to address this major problem. Therefore in this study, the thermal conductivity characteristic and stability of multiwalled carbon nanotube based water nanofluids was investigated. Two types of surfactants namely gum arabic and sodium dodecylbenzene sulphate (SDBS) were used to stabilize the nanofluid. Findings implied that thermal conductivity of water increases with the loading of multiwalled carbon nanotube nanoparticles. As for the stability, study shows that nanofluids added with SDBS are more stable compared to that of samples with gum Arabic.

Electromagnetic Interference Shielding Performances of MWCNT in Concrete Composites

Carbon nanotube (CNT) acts as electromagnetic interference shielding material in concrete composites was presented in this paper. Three concrete samples respectively with different CNT contents were casted and experimentally tested their shielding effectiveness (SE). The SE measurements which were obtained in function of frequency were taken using vector network analyzer (VNA) in the frequency range of 2.4 - 4.0 GHz. The experimental results showed that the CNT contributes to change in conductivity due to the positioning of the electric field of the incident wave and thus, produces different shielding performances. The EMI SE of concrete composites is improved up to 41dB with CNT concentration of 1.5-2.0 wt%.

Thermal Conductivity Enhancement of Graphene Epoxy Nanocomposite

Graphene was introduced in the epoxy matrix for the enhancement of thermal conductivity properties. Dispersion is a crucial step in nanocomposite processing. Therefore, it is important to tackle the issues and homogenously dispersed the graphene in the epoxy matrix. In this paper, we varied the stirring speed in order to understand its effects on enhancing the thermal conductivity values of the composites. Results show that the thermal conductivity increases up to 17.5% with the 1.5% weight loading of graphene that was stirred at 1500 rpm stirring speed. The experiment results are then compared to theoretical calculation by Maxwell model. Study implied that Maxwell model can predict the thermal conductivity of composites because it applies only for small volume fraction of filler. As the filler loading used in this study only up to 1.5 wt. %, Maxwell model was suitable to be used.