Executive Summary : | Nano-bubbles (NB) are bubbles with a diameter less than 1000 microns in a fluid, with applications in water management, agriculture, and medical fields. Bulk NBs are stable, long-lasting gas-filled cavities influenced by Brownian motion and rapidly attach to hydrophobic surfaces. However, their effect on heat transfer applications has not been studied. Initial investigations showed that NB fluids can enhance the Leidenfrost point compared to water, which reduces heat transfer rate. This is desirable for applications like spray cooling. The study aims to test the efficacy of NBs in enhancing evaporation rate or increasing heat transfer in pool-boiling. Studies of evaporation are useful in various applications, such as inkjet patterning, surface patterning, DNA analysis, thermal and nuclear power plants, cryogenic fuel storage, cooling of electronic components, and high-powered lasers. NB fluids will be used as a test fluid for evaporation of sessile and pendant droplets, evaporation rate, and the effect of microtextured surfaces. NB fluids will also be used as a test fluid for studying evaporation in electric fields. In pool boiling, the presence of NBs may be beneficial during both homogeneous and heterogeneous nucleation of bubbles. The heat required to initiate homogeneous nucleation will be less as NBs already exist in the fluid and augment their size on heating. NB fluids will also be tested on textured surfaces. |