Analysis of thermal-hydraulic performance and flow structures of nanofluids across various corrugated channels: An experimental and numerical study

Abstract

The combination of nanofluid and corrugated surface is regarded as a very cost-efficient strategy for providing high heat transfer performance between the target surface and working fluid in different heating and cooling system applications. Herein a comparison study is reported on the thermal performance of different corrugated channels using nanofluids under turbulent flow and constant heat flux conditions. Three shapes, namely, semicircle corrugated channel (SCC), trapezoidal corrugated channel (TCC), and straight channel (SC) are fabricated and tested with 1% and 2% volume fraction of SiO2-water and Al2O3-water nanofluids. Nanoparticles with a size of 20 nm dispersed in water with specific volume fractions are used for comparison and evaluation. The numerical simulations present the flow structures of nanofluids in terms of velocity, isotherms, turbulent viscosity, vorticity and turbulent kinetic energy contours. The findings show that the heat transfer and pressure drop increase as volume fractions of nanofluids and Reynolds number increase. The experiments also revealed that the use of modified channels significantly increases the heat transfer ratio and the greatest enhancement ratio was achieved through the use of a trapezoidal corrugated channel with ϕ=2% of silica nanofluid. Over ranges of considered flow, silica nanofluid was better than alumina nanofluid and the best thermal performance of 1.94 was recorded using silica nanofluid at ϕ=2% and TCC at Reynolds number of 10000. Additionally, new empirical correlations were proposed and reported based on experimental data.