Executive Summary : | The proposed study is concerned with the investigation of fundamental processes/sub-processes that occur during nucleate boiling on a thin ITO coated glass heater surface submerged in a pool of base fluid (water) and/or water-based nanofluids. Alumina (Al2O3) nanoparticles, spherical in shape with diameter of 10-20 nm, are proposed to be used for the preparation of nanofluids. The nanofluids experiments would be conducted in the volumetric range of 0% to 0.02% (V/V). Important bubble dynamic parameters that ultimately govern the boiling process and the associated whole field temperature distributions in the vicinity of the heated substrate as well as around the growing vapor bubble have been proposed to be simultaneously mapped using infrared thermography and refractive index-based imaging techniques. In this direction, rainbow schlieren deflectometry technique is proposed to be employed to visualize the bubble growth and map the space and time resolved temperature field for calculation of relative contributions of different heat transfer mechanisms. IR camera would be used in conjunction with the rainbow schlieren imaging method to map the real time, space-resolved temperature distribution field on the heated substrate surface on which boiling takes place. One of the primary objectives of the proposed work is to carry out the performance evaluation of nanofluids for possible heat transfer enhancement in the context of nucleate boiling heat transfer processes vis-à-vis that of the conventional working fluid i.e. water. Efforts would be made to develop a detailed understanding of the plausible mechanisms through which the nanoparticles influence some of the fundamental sub-processes/parameters, such as bubble departure frequency, microlayer growth and its real time dynamics, growth and development of superheated layer, dynamic contact angle etc. of nucleate boiling phenomena for varying concentrations of nanoparticles. In quantitative terms, the influence of suspended nanoparticles on the relative contributions of various heat transfer mechanisms to the overall heat transfer rate would be determined. |