Nonintrusive investigation of CHF and heat transfer mechanisms associated with silica-water nanofluids and varying wetting surfaces in the context of pool boiling phenomenon

Critical heat flux (CHF) limits the performance of the pool boiling heat transfer by controlling the maximum heat flux that can be dissipated under efficient and safe operating conditions. Recent developments have seen a surge in the application of nanofluids and nanostructured surfaces to achieve enhancement in CHF. The present study focusses on understanding the boiling characteristics, CHF and heat transfer mechanisms, under the application of dilute nanofluids and varying wetting surfaces. In this direction, dilute silica-water nanofluids and silica-coated varying wetting surfaces were employed. Nonintrusive, measurements namely high speed videography and IR thermography were implemented for simultaneous mapping of bubble dynamics and temperature of the heater substrate. The recorded measurements revealed that the nanofluids significantly influence the growth and coalescence dynamics as well as the bubble base evaporation mechanisms on plain surfaces. The boiling experiments with water on varying wetting surfaces showed similar observations. The CHF was seen to increase with the employed nanofluids concentration and the increasing level of surface wettability. A comparative performance analysis between the nanofluids and the wetting surfaces has been presented.