A Critical Review of Experimental Investigations about Convective Heat Transfer Characteristics of Nanofluids under Turbulent and Laminar Regimes with a Focus on the Experimental Setup

Abstract

In this study, several experimental investigations on the effects of nanofluids on the convective heat transfer coefficient in laminar and turbulent conditions were analyzed. The aim of this work is to provide an overview of the thermal performance achieved with the use of nanofluids in various experimental systems. This review covers both forced and natural convection phenomena, with a focus on the different experimental setups used to carry out the experimental campaigns. When possible, a comparison was performed between different experimental campaigns to provide an analysis of the possible common points and differences. A significant increase in the convective heat transfer coefficient was found by using nanofluids instead of traditional heat transfer fluids, in general, even with big data dispersion from one case to another that depended on boundary conditions and the particular experimental setup. In particular, a general trend shows that once a critic value of the Reynolds number or nanoparticle concentrations is reached, the heat transfer performance of the nanofluid decreases or has no appreciable improvement. As a research field still under development, nanofluids are expected to achieve even higher performance and their use will be crucial in many industrial and civil sectors to increase energy efficiency and, thus, mitigate the environmental impact.

Advances in the Development of New Heat Transfer Fluids Based on Nanofluids

“…This topic is growing in importance, and many works have been published so far exploring different aspects. In particular, the work by Colangelo et al [1] is a review of the experimental convective thermal performance of various nanofluids obtained in different working conditions (turbulent and laminar) with an in-depth focus on the experimental setups used for the scientific campaigns. The authors highlighted that in the examined works, the nanofluids always showed a significant improvement in the convective heat transfer coefficient, but with big data dispersion.…”

Green Synthesis, Characterization, and Empirical Thermal Conductivity Assessment of ZnO Nanofluids for High-Efficiency Heat-Transfer Applications

“…The motivation for nanofluids can be traced back to Maxwell’s prediction of improving the thermal conductivity of liquids using solid particles [ 3 ]. Nanofluids have been found to possess enhanced thermo-physical properties such as thermal conductivity, thermal diffusivity, viscosity, and convective heat-transfer coefficients compared to traditional heat-transfer fluids [ 4 ]. Nanofluids might be generated in a single base fluid or a single-phase liquid mixture.…”

EMHD Nanofluid Flow with Radiation and Variable Heat Flux Effects along a Slandering Stretching Sheet

“…They found that a high Peclet number and bio-convection Lewis number lessen the microorganism profiles, but enhance them for high melting parameter values. By considering the impact of Cattaeneo–Christov and convective conditions, Rasool and Wakif [ 27 ] analyzed second-grade flow of nanofluids over a Riga plate and used the spectral local linearization method to find the solution to the problem. Colangelo et al [ 28 ] performed experimental measurements and showed that nanofluids enhance the rate of heat transfer.…”