| As the technological trend of increasing speed and size reduction of components continues the ability to remove high heat fluxes is becoming an ever more critical area of research. Among the topics of research in this area, the use of nanofluids as a heat transfer fluid has drawn much attention recently. Within the last five years work investigating the pool-boiling of these fluid has increased dramatically. However, the existing literature on the subject shows some varying results that need further investigation to interpret. An experimental study was performed studying the behavior of gold nanofluids during pool-boiling. In these experiments it was found that while the heat transfer decreased about 20% over the critical heat flux (CHF) was increased 2.8 times for the 3 nm sized particles. For 15 nm particles the CHF was increased over 3.5 times over pure water with a maximum at nearly 5 times amplification. After performing the experiments, scanning electron microscope images were taken of the surface as a deposition of nanoparticles was observed on the surface. It is this surface deposition that is the source of the altered boiling curves as pure water on the nanoparticle deposited surface behaves similarly to the nanofluid curve. Also, a set of experiments were also performed using HFE 7000 where no CHF enhancement was observed. Further investigation was performed to determine the source of this enhancement including an examination of the wetting characteristics of the surface. However, using existing correlations predicting the critical heat flux it was seen that the wetting of the surface likely is not the sole source of the enhanced CHF. |
