Analysis of Heat Removal Capability of Carbon Nanotube Nanofluid in a Microchannel Heat Sink

International audienceResearch into addressing the exponential increase in heat flux generated by increasing miniaturization of electronic chips has progressed into advanced coolants like the use of nanofluids in a microchannel heat sink (MCHS). Generally known for increased thermal conductivity particularly with a higher concentration, the viscosity of carbon nanotube (CNT) nanofluid, however, has yet to be represented by any acceptable model. Different types of surfactant used to stabilize the CNT nanofluid have reported different thermal resistance to heat flow. This paper presents an analysis of the thermal performance of a rectangular MCHS cooled with CNT nanofluid under various conditions; two different surfactants of Lignin (N2) and Sodium polycarboxylate (N3), different volume fractions between 0.1% to 0.5%, and different heat sink materials. A stochastic approach, multi objective particle swarm optimization (MOPSO) algorithm was developed to minimize the thermal resistance and pumping power simultaneously by optimizing the controlling parameters; the channel aspect ratio and wall width ratio. Results showed that the total reduction of the thermal resistance of CNT nanofluid from that of water is 26.53% at 20°C for nanofluid with both types of surfactant. CNT nanofluids tested outperformed water as a coolant in a MCHS by 0.0623°C/W and 0.0848°C/W at 20°C respectively, though different surfactants showed different degree of improvement in terms of pressure drop. Since a higher volume fraction reduces the thermal resistance at the expense of a higher pressure drop, the optimized pumping power accepted are 0.1% volume fraction and CNT nanofluid with N3 pumping power being higher than CNT nanofluid N2 and water at 20°C