An updated review of nanofluids in various heat transfer devices

Abstract

The field of nanofluids has received interesting attention since the concept of dispersing nanoscaled particles into a fluid was first introduced in the later part of the twentieth century. This is evident from the increased number of studies related to nanofluids published annually. The increasing attention on nanofluids is primarily due to their enhanced thermophysical properties and their ability to be incorporated into a wide range of thermal applications ranging from enhancing the effectiveness of heat exchangers used in industries to solar energy harvesting for renewable energy production. Owing to the increasing number of studies relating to nanofluids, there is a need for a holistic review of the progress and steps taken in 2019 concerning their application in heat transfer devices. This review takes a retrospective look at the year 2019 by reviewing the progress made in the area of nanofluids preparation and the applications of nanofluids in various heat transfer devices such as solar collectors, heat exchangers, refrigeration systems, radiators, thermal storage systems and electronic cooling. This review aims to update readers on recent progress while also highlighting the challenges and future of nanofluids as the next-generation heat transfer fluids. Finally, a conclusion on the merits and demerits of nanofluids is presented along with recommendations for future studies that would mobilise the rapid commercialisation of nanofluids.

Nanofluids in Solar Thermal Collectors: Review and Limitations

“…Nanofluids are a new class of fluids that contain nanometer-sized particles suspended within a base fluid [44,45]. The volume of nanoparticles within the base fluid is measured by the percentage volume fraction or volume concentration.…”

“…As observed by Wole-Osho et al [67], Okonkwo et al [48], and Wang et al [68] both conventional and hybrid nanofluids tend to be more stable as they become either more acidic or more alkaline. The overall stability of nanofluids is not just dependent on fluid pH but also on the nanofluid material, the synthesis technique, and the sonification time [45]. As nanofluid becomes more unstable, the more precipitates are observed within the fluid.…”

“…Several properties affect the rheology and thermal performance of nanofluids; these properties include density (ρ), heat capacity (C p ) , thermal conductivity (k), viscosity (μ), volume concentration (ϕ), shear rate range, particle size, particle shape, etc. [45,71]. Nanofluids are classified into hybrid nanofluids and conventional nanofluids [72].…”

Carbon-Based Nanofluids and Their Advances towards Heat Transfer Applications—A Review

“…In general, two known fabrication processes are currently used for producing nanofluids, namely, the one-step (also referred to as the single-step) method and the two-step approach [ 37 ]. It is important to note that some researchers prefer to classify the one-step production processes into two categories, which are the one-step physical technique and the one-step chemical approach, resulting in three types of methods of nanofluid fabrication for these groups [ 117 , 118 ]. A summary of the two fabrication schemes (i.e., the one-step and two-step methods) is presented in the following subsections.…”

Group Invariant Solutions for Flow and Heat Transfer of Power-Law Nanofluid in a Porous Medium

“…Several studies reported that the thermal performance of nanofluids depends on the dispersion, stability, size, shape, and type of nanoparticles present in the system. e demand for new thermal devices in the electronics, automotive industries, heat exchangers, cooling devices, solar collectors, and many more leads to extensive research carried out to explain the processes of heat transfer in nanofluids [1][2][3][4]. e nanofluid flow and heat transfer over the flat surface had some interesting applications in industrial setups.…”