Download or read book An Experimental Investigation on Heat Transfer Enhancement in Circular Jet Impingement on Hot Surfaces by Using Al2O3 water Nano fluids and Aqueous High alcohol Surfactant Solution written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics and Control of Energy Systems written by Achintya Mukhopadhyay and published by Springer Nature. This book was released on 2019-10-14 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recent advances in dynamics and control of different types of energy systems. It covers research on dynamics and control in energy systems from different aspects, namely, combustion, multiphase flow, nuclear, chemical and thermal. The chapters start from the basic concepts so that this book can be useful even for researchers with very little background in the area. A dedicated chapter provides an overview on the fundamental aspects of the dynamical systems approach. The book will be of use to researchers and professionals alike.
Download or read book Nanoemulsions written by Kai Seng Koh and published by BoD – Books on Demand. This book was released on 2019-09-11 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluidics, an increasingly examined topic in nanoscience and nanotechnology is often discussed with regard to the handling of fluid flow, material processing, and material synthesis in innovative devices ranging from the macroscale to the nanoscale. Nanoemulsions - Properties, Fabrications and Applications reviews key concepts in nanoscale fluid mechanics, its corresponding properties, as well as the latest trends in nanofluidics applications. With attention to the fundamentals as well as advanced applications of fluidics, this book imparts a solid knowledge base and develops skill for future problem-solving and system analysis. This is a vital resource for upper-level engineering students who want to expand their potential career opportunities and familiarize themselves with an increasingly important field.
Download or read book On the Experimental Investigation of the Laminar Convective Heat Transfer of Al2O3 water Nanofluids in a Microchannel written by Ridho Irwansyah and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Characteristics and Convection in Nanofluids written by Aditya Kumar and published by Springer Nature. This book was released on 2021-01-04 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers synthesis, characterization, stability, heat transfer and applications of nanofluids. It includes different types of nanofluids, their preparation methods as well as its effects on the stability and thermophysical properties of nanofluids. It provides a discussion on the mechanism behind the change in the thermal properties of nanofluids and heat transfer behaviour. It presents the latest information and discussion on the preparation and advanced characterization of nanofluids. It also consists of stability analysis of nanofluids and discussion on why it is essential for the industrial application. The book provides a discussion on thermal boundary layer properties in convection. Future directions for heat transfer applications to make the production and application of nanofluids at industrial level are also discussed.
Download or read book Heat Transfer with Nanofluid written by Om Shankar Prajapati and published by . This book was released on 2011-11 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heat Transfer Due to Laminar Natural Convection of Nanofluids written by De-Yi Shang and published by Springer. This book was released on 2018-07-30 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a theoretical study of heat transfer due to laminar natural convection of nanofluids, using Al2O3-water nanofluid as an example. An innovative method of similarity transformation of velocity fields on laminar boundary layers is applied for the development of a mathematical governing model of natural convection with actual nanofluids, and a novel model of the nanofluid's variable thermophysical properties is derived by a mathematical analysis based on the developed model of variable physical properties of fluids combined with the model of the nanofluid's thermal conductivity and viscosity. Based on these, the physical property factors of nanofluids are produced, which leads to a simultaneous solution for deep investigations of hydrodynamics and heat transfer of nanofluid's natural convection. The book also proposes novel predictive formulae for the evaluation of heat transfer of Al2O3-water nanofluid’s natural convection. The formulae have reliable theoretical and practical value because they are developed by rigorous theoretical analysis of heat transfer combined with full consideration of the effects of the temperature-dependent physical properties of nanofluids and the nanoparticle shape factor and concentration, as well as variations of fluid boundary temperatures. The conversion factors proposed help to turn the heat transfer coefficient and rate of fluid natural convection into those of nanofluid natural convection. Furthermore, several calculation examples are provided to demonstrate the heat transfer application of the proposed predictive formulae.
Download or read book Nanofluids for Heat Exchangers written by Hafiz Muhammad Ali and published by Springer Nature. This book was released on 2022-08-31 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the importance of heat transfer in heat exchangers, and fluids properties play a vital role to increase heat transfer rate translating the size of the equipment and cuts in the capital and running cost in the long term. Nanofluids applications in heat exchangers will help to improve the thermophysical properties of the fluid and therefore heat transfer. And, this book explains the enhancing mechanisms of heat transfer by employing nanofluids in heat exchangers. A critical discussion will enable to estimate the pros and cons of such fluids in different types of heat exchangers. Prevailing working conditions for short- and long-term implementation of various types of nanofluids will be discussed and introduced to the readers. This book helps the researchers, scientist and academicians working in the domain to be able to get a comprehensive knowledge at one place regarding the preparation, properties, measurements, data reduction, characteristics and applications of nanofluids in heat exchangers.
Download or read book Experimental Investigation of Forced Convection Heat Transfer of Nanofluids in a Microchannel Using Temperature Nanosensors written by Jiwon Yu and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments were performed to study forced convective heat transfer of de-ionized water (DI water) and aqueous nanofluids flowing in a microchannel. An array of temperature nanosensors, called "Thin Film Thermocouples (TFT)", was utilized for performing the experimental measurements. TFT arrays were designed (which included design of photomask layout), microfabricated, packaged and assembled for testing with the experimental apparatus. Heat removal rates from the heated surface to the different testing fluids were measured by varying the coolant flow rates, wall temperatures, nanoparticle material, nanoparticle morphology (shape and nanoparticle size) as well as mass concentrations of nanoparticles in the coolants. Anomalous thermal behavior was observed in the forced convective heat transfer experiments. Precipitation of the nanoparticles on the heat exchanging surface was monitored using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray spectroscopy (EDX). Isolated precipitation of nanoparticles is expected to cause formation of "nanofins" leading to enhancement of surface area and thus resulting in enhanced convective heat transfer to the nanofluid coolants. However, excessive precipitation (caused due to the agglomeration of the nanoparticles in the nanofluid coolant) causes scaling (fouling) of the heat exchanging surfaces and thus results in degradation of convective heat transfer. This study shows that the surface morphology plays a crucial role in determining the efficacy of convective heat transfer involving suspensions of nanoparticles in coolants (or nanofluids). Flow visualization and quantitative estimation of near-wall temperature profiles were performed using quantum dots and fluorescent dyes. This non-contact measurement technique for temperature and flow profiles in microchannels using quantum dots is expected to make pioneering contribution to the field of experimental flow visualization and to the study of micro/nano-scale heat transfer phenomena, particularly for forced convective heat transfer of various coolants, including nanofluids. Logical extensions of this study were explored and future directions were proposed. Preliminary experiments to demonstrate feasibility showed significant enhancement in the flow boiling heat flux values for nanofluids compared to that of pure solvent (DIW). Based on the novel phenomena observed in this study several other topics for future research were suggested, such as, using Surface Plasmon Resonance (SPR) platforms to monitor precipitation of nanoparticles on microchannel surfaces in real time (e.g., for generating surface isotherms). The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148235
Download or read book Nanoparticle Heat Transfer and Fluid Flow written by W. J. Minkowycz and published by CRC Press. This book was released on 2016-04-19 with total page 335 pages. Available in PDF, EPUB and Kindle. Book excerpt: Featuring contributions by leading researchers in the field, Nanoparticle Heat Transfer and Fluid Flow explores heat transfer and fluid flow processes in nanomaterials and nanofluids, which are becoming increasingly important across the engineering disciplines. The book covers a wide range, from biomedical and energy conversion applications to mate
Download or read book Heat Transfer Enhancement with Nanofluids written by Vincenzo Bianco and published by CRC Press. This book was released on 2015-04-01 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanofluids are gaining the attention of scientists and researchers around the world. This new category of heat transfer medium improves the thermal conductivity of fluid by suspending small solid particles within it and offers the possibility of increased heat transfer in a variety of applications. Bringing together expert contributions from
Download or read book Experiments on Laminar Convective Heat Transfer with R Al2O3 Nanofluids written by Wei-Yun Lai and published by . This book was released on 2010 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: As miniature and high-heat-dissipation equipment became major manufacture and operation trends, heat-rejecting and heat-transport solutions faced increasing challenges. In the 1970s, researchers showed that particle suspensions can enhance the heat transfer efficiency of their base fluids. However, their work was hindered by the sedimentation and erosion issues caused by the relatively large particle sizes in their suspensions. More recently, nanofluids--suspensions of nanoparticles in liquids-were proposed to be applied as heat transfer fluids, because of the enhanced thermal conductivity that has generally been observed. However, in practical applications, a heat conduction mechanism may not be sufficient for cooling high-heat-dissipation devices such as microelectronics or powerful optical equipment. Thus, the thermal performance under convective, i.e., flowing heat transfer conditions becomes of primary interest. In addition, with the presence of nanoparticles, the viscosity of a nanofluid is greater than its base fluid and deviates from Einstein's classical prediction. Through the use of a test rig designed and assembled as part of this dissertation, the viscosity and heat transfer coefficient of nanofluids can be simultaneously determined by pressure drop and temperature difference measurements under laminar flow conditions. An extensive characterization of the nanofluid samples, including pH, electrical conductivity, particle sizing and zeta potential, is also documented. Results indicate that with constant wall heat flux, the relative viscosities of nanofluid decrease with increasing volume flow rate. The results also show, based on Brenner's model, that the nanofluid viscosity can be explained in part by the aspect ratio of the aggregates. The measured heat transfer coefficient values for nanofluids are generally higher than those for base fluids. In the developing region, this can be at least partially explained by Prandtl number effects. The Nusselt number (Nu) results for nanofluid show that Nu increases with increasing nanofluid volume fraction and volume flow rate. However, only DI-H2O (deionized water) and 5/95 PG/H2O (PG = propylene glycol) based nanofluids with 1 vol% nanoparticle loading have Nu greater than the theoretical prediction, 4.364. It is suggested that the nanofluid has potential to be applied within the thermally developing region when utilizing the nanofluid as a heat transfer liquid in a circular tube. The suggested Reynold's number is greater than 100.
Download or read book Multiple Jet Impingement Heat Transfer Characteristic written by and published by . This book was released on 1980 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation on Natural Convection of AI2O3 water Nanofluids in Cavity Flow written by Hadi Ghodsinezhad and published by . This book was released on 2016 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thermophysical properties of nanofluids have attracted the attention of researchers to a far greater extent than the heat transfer characteristics of nanofluids have. Contradictory results on the thermal-fluid behaviour of nanofluids have been numerically and experimentally reported on in the open literature. Natural convection has not been investigated experimentally as much as the other properties of nanofluids. In this study, the characteristics and stability of Al2O3-water nanofluids (d = 20 30 nm) were analysed using a Malvern zetasizer, zeta potential and UV-visible spectroscopy. The natural convection of Al2O3- water nanofluids (formulated with a single-step method) was experimentally studied in detail for the volume fractions 0, 0.05, 0.1, 0.2, 0.4 and 0.6% in a rectangular cavity with an aspect ratio of 1, heated differentially on two opposite vertical walls for the Rayleigh number (Ra) range 3.49 x 108 to 1.05 x 109. The viscosity of Al2O3-water nanofluids measured between 15 and 50 °C. The effect of temperature and volume fraction on viscosity was also investigated. A detailed study of the nanoparticle concentration effect on the natural convection heat transfer coefficient was performed. It was found that increasing the concentration of nanoparticles improves the heat transfer coefficient by up to 15% at a 0.1% volume fraction. Further increasing the concentration of nanoparticles causes the natural convection heat transfer coefficient to deteriorate. This research also supports the idea that "for nanofluids with thermal conductivity more than the base fluids an optimum concentration may exist that maximises heat transfer in an exact condition as natural convection, laminar force convection or turbulence force convection".
Download or read book Hydrodynamics of Droplet Impingement on Heated Surfaces written by Jian Shen and published by . This book was released on 2010 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigates the hydrodynamic characteristics of droplet impinging on heated surfaces using High Speed High Resolution (HSHR) imaging and evaluates the effect of surface temperature and using water and a nanofluid on a polished and a nano-structured surface. Three types of surfaces are used in the study: polished silicon, nano-structured porous silicon and gold coated polished silicon. Seven different surface temperatures including single phase (non-boiling) and two phase (boiling) conditions are studied. Droplet impact velocity, transient spreading diameter and dynamic contact angle are determined using image processing. Five stages are observed during impingement: initial impact, boiling (if the surface temperature is high enough), near constant wetting diameter evaporation, fast receding contact line evaporation and final dry-out. Results of water and a water based single-wall-carbon-nano-tube (SWCNT) nanofluid impinging on a polished silicon surface are compared to determine effects of nano-particles on impinging dynamics. The data show that the nanofluid exhibits larger spreading velocities, larger spreading diameters and an increase in early stage dynamic contact angle. The results of water impinging on both polished silicon and nano-structured silicon disks are compared to determine effects of the nano-structured surface on impingement dynamics. It is found that the nano-structured surface enhances the heat transfer for evaporative cooling at lower surface temperatures which is indicated by a shorter evaporation time. Ultimately, using nanofluid and nano-structured surface can reduce the total evaporation time up to 37% and 20%, respectively. Experimental data are compared with models that predict dynamic contact angle and non-dimensional maximum spreading diameter. Results show that the molecular-kinetic theory's dynamic contact angle model (M-K model) agrees well with current experimental data at low velocities range corresponding to later times during impingement, but over-predict at high velocities range corresponding to early times of initial impact. Predictions of maximum spreading diameter based on surface energy analysis are compared with current experimental data. Results indicate that all the four models over-predict unless empirical coefficients are adjusted to fit the test conditions.
Download or read book Evaluation of Alumina Nanofluids and Surfactant Drag Reducing Solutions to Improve Heat Transfer for Aircraft Cooling Systems written by Javier Artemio Narvaez Bazan and published by . This book was released on 2018 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a critical need for improved coolants for military aircraft applications. Research in this area has focused on either synthesizing novel coolants with improved thermal properties or developing additives for current coolants that can improve heat transfer capability in recirculating systems. This dissertation focuses on the latter alternative investigating the effect of nanoparticles or drag-reducing surfactant additives on effective heat transfer coefficients. Nanoparticles are reported to not only enhance thermal conductivity of coolants, but also increase the heat transfer coefficient. Some setbacks related to the use of nanofluids have been identified, such as increased pressure loss, erosion, and fluid instability. Surfactant drag-reducing additives greatly reduce skin friction, thereby reducing resistance to flow in tubes. Lower flow resistance means that the volumetric flow rate can be greatly increased at constant pumping power. Under these circumstances, the heat transfer coefficient can be enhanced. However, researchers have found that the heat transfer coefficient in tube heat exchangers is reduced by the addition of drag-reducing additives. Moreover, the percentage of heat transfer reduction in tube heat exchangers is greater than the corresponding drag reduction. The reason for the loss of heat transfer is that surfactant drag reducers lower flow resistance by damping turbulent eddies, which are known to drive heat transfer. Several researchers have tried to overcome heat transfer reduction in heat exchangers by different means described in this dissertation. However, despite their efforts, the improvements they achieved were not enough to eliminate the heat transfer reduction. Instead of focusing on turbulence, this dissertation explored the impact of increased heat transfer area per volume within microchannel devices, as the flow regime is typically laminar. The objective of this dissertation is to evaluate two approaches for heat transfer enhancement by additives--nanoparticles and surfactants--in aircraft cooling systems. For proof-of-concept experiments carried out in this work, the base fluid selected was DI water. A computational fluid dynamics study on the pressure, velocity, and temperature profiles was performed to analyze the flow and temperature patterns inside a cold plate, the microcooling device used in this research. A small study on the flow inside an elbow was also performed to analyze secondary flows. Alumina/DI water nanofluids were evaluated at system level. It was observed that, at the same volumetric flow, there was no significant improvement in convective heat transfer coefficients. Problems such as increase of pressure loss, particle settling, and especially vaporization were observed. Next, an aqueous surfactant solution was also tested within the heat exchanger system. A small reduction in both pressure loss and heat transfer coefficient at the system level was found. The relatively high pressure loss was due to the large ratio of form friction to total friction. Other problems associated with the use of surfactants as a heat transfer enhancer were surfactant poisoning and chemical degradation. Finally, alternatives to improve heat transfer coefficient by nanoparticles and surfactant additives are proposed, based on the analysis identified by this study.
Download or read book Convection in Ferro Nanofluids Experiments and Theory written by Aleksandra A. Bozhko and published by Springer. This book was released on 2018-08-25 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the experimental and theoretical study of convection in non-isothermal ferro-nanofluids (FNFs). Since FNFs are not transparent and magnetic fields are very sensitive to the shape of the boundary between magnetic and nonmagnetic media, special flow visualization techniques based on the use of thermo-sensitive liquid crystal films, infrared cameras, as well as local and integral temperature sensors are discussed in the book. This book considers several major configurations of convective chambers and the applied magnetic field. For each of them, the stability boundaries are determined theoretically and experimentally. The physical types of dominant instabilities and the characteristics of their interactions are subsequently established using linear and weakly non-linear hydrodynamic stability analyses and elements of bifurcation theory. The book also discusses the potential of using magnetically controlled ferro-nanofluids as a heat carrier in situations where heat removal by natural convection is not possible due to the lack of gravity (orbital stations) or extreme confinement (microelectronics). Researchers and practitioners working in the areas of fluid mechanics, hydrodynamic stability, and heat and mass transfer will benefit from this book.
