Experimental studies of nanofluid thermal conductivity enhancement and applications: A review

Abstract

In many applications, there is a critical need for enhancing the poor thermal conductivity of conventional fluids in order to develop efficient heat transfer fluids. This requirement can be met through dispersing nanometric particles in a given base fluid such as water, ethylene glycol, oil or air. The resulting nanofluids enhanced thermal conductivity of the base fluids. In order to evaluate this enhancement, nanofluid thermal conductivity is required to be measured. Several methods and techniques are covered in the present contribution. In addition, enhancements recorded experimentally are reviewed and summarized. Different parameters affecting on such enhancement are covered, including: nanoparticle concentration, size, shape and thermal conductivity. In addition, base fluid type, nanofluid bulk temperature and dispersion techniques are also covered parameters. However, nanofluids have the potential to contribute in several practical applications including solar thermal, transportation, electronic cooling, medical, detergency and military applications. In the present work, a brief overview of evolution in the use of nanofluids in some applications has been presented. According to this contribution, there is a critical need for further fundamental and applications of nanofluids studies in order to understand the physical mechanisms of using nanofluids as well as explore different aspects of applications of nanofluids.

A Review on Nanofluids: Fabrication, Stability, and Thermophysical Properties

“…This category of nanofluid was first proposed by Choi, in 1995, and is considered as the conventional form of nanofluids used, where a single type of nanoparticles is used to produce the suspension via different preparation methods [5]. It was reported by many authors that nanofluids of such category are superior in performance, due to having much more favourable thermophysical properties than their basefluid [51,[101][102][103][104].…”

Aqueous Nanofluids Based on Copper MPA: Synthesis and Characterization

“…8 Nanofluids are composites formed by the stable colloidal dispersion of nanomaterials (with a size less than 100 m) in a conventional cooling fluid. [3][4][5][6][7][8][9][10][11] Conventional fluids used in liquid refrigeration, such as water, ethylene glycol and oils, have low thermal conductivity (thermal conductivity of water 0.613 W/m·K at 300 K), while solid materials, on the other hand, have higher thermal conductivity values. Due to the high thermal conductivity of solids, the addition of nanomaterials (such as ceramics, metals, alloys, semiconductors and carbon derivatives) is a way of increasing the thermal conductivity of conventional fluids, resulting in a fluid composite with higher heat exchange efficiency.…”

“…In addition, nanomaterials can flow smoothly without causing clogging of refrigeration systems and provide improvements in the thermal properties of the fluid. [9][10][11][12] The key issue to obtaining efficient nanofluids is to synthesize nanomaterials that have appreciable colloidal stability by modifying or functionalizing their surfaces. Aiming to produce nanofluids with higher colloidal stability in recent years, several materials have been studied as surface agents of nanoparticles, such as polymers, surfactants, aminosilanes and other multifunctional molecules.…”

“…[14][15][16] Nanofluids are produced by two different routes, designated as a one-step method and a two-step method. [4][5][6][7][8][9][10][11][12] In the onestep method, the nanomaterials were synthesized directly in a conventional cooling fluid, forming the nanofluid. The major advantage of this method is to avoid the formation of nanoparticle agglomerates, which favors the colloidal stability of the nanofluids.…”

MHD boundary layer bionanoconvective non‐Newtonian flow past a needle with Stefan blowing

“…The study of nanofluids has attracted much attention of researchers because of the diverse applications. Tawfik has reviewed and summarized the cases of enhanced nanofluid thermal conductivity via nanofluid. A measurement of the thermal conductivity coefficient of nanofluids has been conducted by Pryazhnikov et al, and the results show that the nanofluid thermal conductivity coefficient enhances with increasing particle size.…”