This paper presents a critical review of heat transfer applications of nanofluids. The effects of nanoparticle concentration, size, shape, and nanofluid flow rate on Nusselt number, heat transfer coefficient, thermal conductivity, thermal resistance, friction factor and pressure drop from numerous studies reported recently are presented. Effects of various geometric parameters on heat transfer enhancement of system using nanofluids have also been reviewed. Heat transfer devices covered in this paper include radiators, circular tube heat exchangers, plate heat exchangers, shell and tube heat exchangers and heat sinks. Various correlations used for experimental validation or developed in reviewed studies are also compiled, compared and analyzed. The pros and cons associated to the applications of nanofluids in heat transfer devices are presented in details to determine the future direction of research in this arena.

Recent advances in application of nanofluids in heat transfer devices: A critical review

Towards hybrid nanofluids: Preparation, thermophysical properties, applications, and challenges

Nanomedicine has attracted increasing attention in recent years, because it offers great promise to provide personalized diagnostics and therapy with improved treatment efficacy and specificity. In this study, we developed a gold nanostar (GNS) probe for multi-modality theranostics including surface-enhanced Raman scattering (SERS) detection, x-ray computed tomography (CT), two-photon luminescence (TPL) imaging, and photothermal therapy (PTT). We performed radiolabeling, as well as CT and optical imaging, to investigate the GNS probe's biodistribution and intratumoral uptake at both macroscopic and microscopic scales. We also characterized the performance of the GNS nanoprobe for in vitro photothermal heating and in vivo photothermal ablation of primary sarcomas in mice. The results showed that 30-nm GNS have higher tumor uptake, as well as deeper penetration into tumor interstitial space compared to 60-nm GNS. In addition, we found that a higher injection dose of GNS can increase the percentage of tumor uptake. We also demonstrated the GNS probe's superior photothermal conversion efficiency with a highly concentrated heating effect due to a tip-enhanced plasmonic effect. In vivo photothermal therapy with a near-infrared (NIR) laser under the maximum permissible exposure (MPE) led to ablation of aggressive tumors containing GNS, but had no effect in the absence of GNS. This multifunctional GNS probe has the potential to be used for in vivo biosensing, preoperative CT imaging, intraoperative detection with optical methods (SERS and TPL), as well as image-guided photothermal therapy.

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A Plasmonic Gold Nanostar Theranostic Probe for In Vivo Tumor Imaging and Photothermal Therapy

Applications of hybrid nanofluids in solar energy, practical limitations and challenges: A critical review

Steam generation in a nanoparticle-based solar receiver

Optimization of short micro pin fins in minichannels

An overview of nanoparticle assisted laser therapy

Researchers are looking to utilize nanofluids as a way to increase the efficiency in solar energy applications. Metallic particles are becoming popular because of the plasmonic characteristics allowing for more absorption. Only homogenous nanofluids for solar applications have been considered. This article proposes the use of a hybrid nanofluid containing multiple types of nanoparticles with water as the base fluid exposed to radiation. This hybrid mixture can utilize a broader wavelength spectrum and absorb more heat. Recipes for combining gold, copper, aluminum, graphite, and silicon dioxide gold nanoparticles into water are given graphically and numerically for different concentrations, diameters, and container heights.

Toni K. Tullius

Papers

Optimization of short micro pin fins in minichannels

An overview of nanoparticle assisted laser therapy

Analysis of a hybrid nanofluid exposed to radiation

Analysis of relaxation times on the human head using the thermal wave model

Temperature of a metallic nanoparticle embedded in a phase change media exposed to radiation