Characteristics investigation on heat transfer growth of sonochemically synthesized ZnO-DW based nanofluids inside square heat exchanger

Abstract: In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers around the world. The present research investigates the growth in heat transfer using ZnO-DW based nanofluids in a square heat exchanger. ZnO nanoparticles were synthesized by using the single-pot sonochemical technique. The ZnO-DW based nanofluids with different concentrations (0.1, 0.075, 0.05 and 0.025 mass%) were prepared by using probe sonication technique. The heat transfer growth will be benchmarked using the experimental data from distilled water experiment. Reynolds numbers, average convective heat transfer coefficient (h), and Nusselt number were calculated and analyzed in this investigation. Significant enhancement of 52% in thermal conductivity was noticed at 45 °C for 0.1 mass% concentration of ZnO-DW based nanofluids, which is due to the presence of maximum ZnO nanoparticles. Moreover, the maximum improvement in Nusselt values recorded at the end of the square pipe is 47% for 0.1 mass%, while 32%, 27% and 17% increase was recorded for 0.075, 0.05 and 0.025 mass% concentrations, and heat transfer enhancement was from 500 to 1100, 500 to 960, 500 to 910, and 500 to 900 W m⁻² K⁻¹ for different ZnO-DW based nanofluids mass% concentrations, which is more than water due to stability of nanoparticles. It can be concluded that the heat transfer performance enhancement is credited to the combination of square pipe and well-dispersed and stable ZnO-DW based nanofluids for heat exchanger applications. Graphic abstract: [Figure not available: see fulltext.]