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

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An updated review of nanofluids in various heat transfer devices

Nanofluids have opened the doors towards the enhancement of many of today’s existing thermal applications performance. This is because these advanced working fluids exhibit exceptional thermophysical properties, and thus making them excellent candidates for replacing conventional working fluids. On the other hand, nanomaterials of carbon-base were proven throughout the literature to have the highest thermal conductivity among all other types of nanoscaled materials. Therefore, when these materials are homogeneously dispersed in a base fluid, the resulting suspension will theoretically attain orders of magnitude higher effective thermal conductivity than its counterpart. Despite this fact, there are still some challenges that are associated with these types of fluids. The main obstacle is the dispersion stability of the nanomaterials, which can lead the attractive properties of the nanofluid to degrade with time, up to the point where they lose their effectiveness. For such reason, this work has been devoted towards providing a systematic review on nanofluids of carbon-base, precisely; carbon nanotubes, graphene, and nanodiamonds, and their employment in thermal systems commonly used in the energy sectors. Firstly, this work reviews the synthesis approaches of the carbon-based feedstock. Then, it explains the different nanofluids fabrication methods. The dispersion stability is also discussed in terms of measuring techniques, enhancement methods, and its effect on the suspension thermophysical properties. The study summarizes the development in the correlations used to predict the thermophysical properties of the dispersion. Furthermore, it assesses the influence of these advanced working fluids on parabolic trough solar collectors, nuclear reactor systems, and air conditioning and refrigeration systems. Lastly, the current gap in scientific knowledge is provided to set up future research directions.

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

Construction companies are booming both in urban and quickly developing cities throughout the world. Besides, the manufacturers and researchers are trying to focus more on lignocellulosic fiber-bas...

Lignocellulosic Fiber Cement Compatibility: A State of the Art Review

The popularity of the studies on improving the thermal properties of base fluids in thermal engineering applications is considerably increasing day by day. Recently, many researchers have proved that the use of nanoparticles along with the base fluids exhibits better thermal properties as well as better system performance. In line with this, it is noticed a respectful increase in the number of studies regarding nanoparticle use in refrigeration systems. Accordingly, the present paper aims to summarize the preparation of nanofluids, the variation of thermophysical properties, the stability of nanofluids, impacts on the system performances of nanofluid usage, limitations, and challenges of nanoparticle usage, particularly in the refrigeration systems. Previous studies revealed that the heat transfer mechanism of the lubricants and refrigerants is highly improved with nanoparticle addition. It is observed that the increase in thermal properties becomes more visible as nanoparticle fractions increase, but this case may worsen the viscosity of nanofluids. The enhanced thermal properties contribute to improving refrigeration system performance. Many papers emphasize that nanoparticle-doping triggers an increase in system performance by both reducing the compressor power input and increasing the cooling capacity of the refrigeration systems. However, some critical points such as stability, homogeneous distribution, agglomeration, and sedimentation considerably influence the sustainability of performance improvement. In conclusion, nanoparticle-doping for refrigeration systems can be accepted as a very promising way of improving the performance, nevertheless, some questions such as high cost, toxic effect, poor stabilization, erosion effect, high viscosity, clogging issues should be more addressed in the future.

A review of stability, thermophysical properties and impact of using nanofluids on the performance of refrigeration systems

Analysis of Cascade Vapour Refrigeration System with Various Refrigerants

Influence of stacking sequence and fiber treatment on mechanical properties of carbon-jute-banana reinforced epoxy hybrid composites

Analysis and Feasibilty of Nano-Lubricant in Vapour Compression Refrigeration System

Subsonic commercial aircraft operate with turbo-fan engines that operate with moderate bypass ratio (BR) co-flowing jets (CFJ). This study aims to analyse CFJ with constant BR 6.3 and varying primary nozzle lip thickness (LT) to find a critical LT in CFJ below which mixing enhances and beyond which mixing inhibits.,CFJ were characterized with a constant BR of 6.3 and varying lip thicknesses. A single free jet with a diameter equal to that of a primary nozzle of the co-flowing jet was also studied for comparison.,The results show that within a critical limit, the mixing enhanced with an increase in LT. This was signified by a reduction in potential core length (PCL). Beyond this limit, mixing inhibited leading to the elongation of PCL. This limit was controlled by parameters such as LT and magnitude of BR.,The BR value of CFJ in the present study was 6.3. This lies under the moderate BR value at which subsonic commercial turbofan operates. Hence, it becomes impervious to study its mixing behavior.,This is the first effort to find the critical value of LT for a constant BR for compressible co-flow jets. The CFJ with moderate BR and varying LT has not been studied in the past. The present study focuses on finding a critical LT below which mixing enhances and above which mixing inhibits.

Characteristics of a co-flowing jet with varying lip thickness and constant velocity ratio

The single pass shell and multi-tube heat exchanger with double segmental baffles'’ performance improvement were experimentally investigated by two methods of air injection into shell side ...

Study on performance of horizontal single pass shell and multi-tube heat exchanger with baffles by air bubble injection

A parallel flow heat exchanger containing conical sectional inserts with three different pitch ratio (i.e., 1, 2, and 3) in a different orientation to the flow direction of the working fluid had be...

N. Dilip Raja

Papers

Influence of stacking sequence and fiber treatment on mechanical properties of carbon-jute-banana reinforced epoxy hybrid composites

Analysis and Feasibilty of Nano-Lubricant in Vapour Compression Refrigeration System

Characteristics of a co-flowing jet with varying lip thickness and constant velocity ratio

Study on performance of horizontal single pass shell and multi-tube heat exchanger with baffles by air bubble injection

Experimental study on Al2O3 /H2O nanofluid with conical sectional insert in concentric tube heat exchanger