Review and Comparison of Nanofluid Thermal Conductivity and Heat Transfer Enhancements

TLDR

Nanofluid technology is a nascent field with limited supporting studies. This study reviews the literature and evaluates R&D results to establish the current status of nanofluid technology for heat transfer applications. The authors examined experimental data on thermal conductivity and convective heat transfer of nanofluids versus conventional fluids, considering particle concentration, material, size, shape, base fluid, temperature, additives, and acidity, and recast results using a common parameter to enable cross‑study comparisons. Heat‑transfer enhancement with nanofluids ranges from 15–40%, with some cases achieving orders‑of‑magnitude improvements, though data remain inconclusive or conflicting in certain areas.

Abstract

This study provides a detailed literature review and an assessment of results of the research and development work forming the current status of nanofluid technology for heat transfer applications. Nanofluid technology is a relatively new field, and as such, the supporting studies are not extensive. Specifically, experimental results were reviewed in this study regarding the enhancement of the thermal conductivity and convective heat transfer of nanofluids relative to conventional heat transfer fluids, and assessments were made as to the state-of-the-art of verified parametric trends and magnitudes. Pertinent parameters of particle volume concentration, particle material, particle size, particle shape, base fluid material, temperature, additive, and acidity were considered individually, and experimental results from multiple research groups were used together when assessing results. To this end, published research results from many studies were recast using a common parameter to facilitate comparisons of data among research groups and to identify thermal property and heat transfer trends. The current state of knowledge is presented as well as areas where the data are presently inconclusive or conflicting. Heat transfer enhancement for available nanofluids is shown to be in the 15–40% range, with a few situations resulting in orders of magnitude enhancement.