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Author: Aditya Bansal Publisher: ISBN: Category : Languages : en Pages :
Book Description
ABSTRACT: Nanofluids have been demonstrated to be promising for heat transfer enhancement in forced convection and boiling applications. The addition of carbon, copper, and other high-thermal-conductivity material nanoparticles to water, oil, ethylene glycol, and other fluids has been determined to increase the thermal conductivities of these fluids. The increased effective thermal conductivities of these fluids enhance their abilities to dissipate heat in such applications. The use of nanofluids for spray cooling is an extension of the application of nanofluids for enhancement of heat dissipation. In this investigation, experiments were performed to determine the level of heat transfer enhancement with the addition of alumina nanoparticles to the fluid. Using mass percentages of up to 0.5% alumina nanoparticles suspended in water, heat fluxes and surface temperatures were measured and compared. Compressed nitrogen was used to provide constant spray nozzle pressures to produce full-cone sprays in an open loop spray cooling system. The range of heat fluxes measured were for single-phase and phase-change spray cooling regimes.
Author: Aditya Bansal Publisher: ISBN: Category : Languages : en Pages :
Book Description
ABSTRACT: Nanofluids have been demonstrated to be promising for heat transfer enhancement in forced convection and boiling applications. The addition of carbon, copper, and other high-thermal-conductivity material nanoparticles to water, oil, ethylene glycol, and other fluids has been determined to increase the thermal conductivities of these fluids. The increased effective thermal conductivities of these fluids enhance their abilities to dissipate heat in such applications. The use of nanofluids for spray cooling is an extension of the application of nanofluids for enhancement of heat dissipation. In this investigation, experiments were performed to determine the level of heat transfer enhancement with the addition of alumina nanoparticles to the fluid. Using mass percentages of up to 0.5% alumina nanoparticles suspended in water, heat fluxes and surface temperatures were measured and compared. Compressed nitrogen was used to provide constant spray nozzle pressures to produce full-cone sprays in an open loop spray cooling system. The range of heat fluxes measured were for single-phase and phase-change spray cooling regimes.
Author: Christian David Martinez Publisher: ISBN: Category : Languages : en Pages :
Book Description
ABSTRACT: Spray cooling is a technique for achieving large heat fluxes at low surface temperatures by impinging a liquid in droplet form on a heated surface. Heat is removed by droplets spreading across the surface, thus removing heat by evaporation and by an increase in the convective heat transfer coefficient. The addition of nano-sized particles, like aluminum or copper, to water to create a nanofluid could further enhance the spray cooling process. Nanofluids have been shown to have better thermophysical properties when compared to water, like enhanced thermal conductivity. Although droplet size, velocity, impact angle and the roughness of the heated surface are all factors that determine the amount of heat that can be removed, the dominant driving mechanism for heat dissipation by spray cooling is difficult to determine. In the current study, experiments were conducted to compare the enhancement to heat transfer caused by using alumina nanofluids during spray cooling instead of de-ionized water for the same nozzle pressure and distance from the heated surface. The fluids were sprayed on a heated copper surface at a constant distance of 21 mm. Three mass concentrations, 0.1%, 0.5%, and 1.0%, of alumina nanofluids were compared against water at three pressures, 40psi, 45psi, and 50psi. To ensure the suspension of the aluminum oxide nanoparticles during the experiment, the pH level of the nanofluid was altered. The nanofluids showed an enhancement during the single-phase heat transfer and an increase in the critical heat flux (CHF). The spray cooling heat transfer curve shifted to the right for all concentrations investigated, indicating a delay in two-phase heat transfer. The surface roughness of the copper surface was measured before and after spray cooling as a possible cause for the delay.
Author: Vincenzo Bianco Publisher: CRC Press ISBN: 1482254026 Category : Science Languages : en Pages : 473
Book Description
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
Author: Javier Artemio Narvaez Bazan Publisher: ISBN: Category : Jet engines Languages : en Pages : 313
Book Description
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.
Author: Aditya Kumar Publisher: Springer Nature ISBN: 981334248X Category : Science Languages : en Pages : 230
Book Description
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.
Author: Li, Changhe Publisher: IGI Global ISBN: 179981548X Category : Technology & Engineering Languages : en Pages : 441
Book Description
In today’s modern world, the manufacturing industry is embracing an energy-efficient initiative and adopting green techniques. One aspect that has failed to adopt this scheme is flood grinding. Current flood grinding methods increase the treatment cost of grinding fluid and waste large quantities. In order to remain sustainable and efficient, in-depth research is necessary to study green grinding technologies that can ensure machining precision and surface quality of workpiece and reduce grinding fluid-induced environmental pollution. Enhanced Heat Transfer Mechanism of Nanofluid MQL Cooling Grinding provides emerging research exploring the theoretical and practical aspects of nanofluid lubrication and its application within grinding flow and green manufacturing. Featuring coverage on a broad range of topics such as airflow distribution, morphology analysis, and lubrication performance, this book is ideally designed for mechanical professionals, engineers, manufacturers, researchers, scientists, academicians, and students seeking current research on clean and low-carbon precision machining methods.
Author: Bharat Bhanvase Publisher: Academic Press ISBN: 0128219475 Category : Technology & Engineering Languages : en Pages : 460
Book Description
Nanofluids for Heat and Mass Transfer: Fundamentals, Sustainable Manufacturing and Applications presents the latest on the performance of nanofluids in heat transfer systems. Dr. Bharat Bhanvase investigates characterization techniques and the various properties of nanofluids to analyze their efficiency and abilities in a variety of settings. The book moves through a presentation of the fundamentals of synthesis and nanofluid characterization to various properties and applications. Aimed at academics and researchers focused on heat transfer in energy and engineering disciplines, this book considers sustainable manufacturing processes within newer energy harvesting technologies to serve as an authoritative and well-rounded reference. Highlights the major elements of nanofluids as an energy harvesting fluid, including their preparation methods, characterization techniques, properties and applications Includes valuable findings and insights from numerical and computational studies Provides nanofluid researchers with research inspiration to discover new applications and further develop technologies
Author: G. M. Carlomagno Publisher: WIT Press ISBN: 1845645405 Category : Mathematics Languages : en Pages : 737
Book Description
Containing edited versions of most of the papers presented at the Fifteenth International Conference on Computational Methods and Experimental Measurements, this book reviews the latest work on these two approaches, and the interaction between them.
Author: Ali Mohammad Publisher: Springer Science & Business Media ISBN: 9400717121 Category : Science Languages : en Pages : 440
Book Description
The conventional solvents used in chemical, pharmaceutical, biomedical and separation processes represent a great challenge to green chemistry because of their toxicity and flammability. Since the beginning of “the 12 Principles of Green Chemistry” in 1998, a general effort has been made to replace conventional solvents with environmentally benign substitutes. Water has been the most popular choice so far, followed by ionic liquids, surfactant, supercritical fluids, fluorous solvents, liquid polymers, bio-solvents and switchable solvent systems. Green Solvents Volume I and II provides a throughout overview of the different types of solvents and discusses their extensive applications in fields such as extraction, organic synthesis, biocatalytic processes, production of fine chemicals, removal of hydrogen sulphide, biochemical transformations, composite material, energy storage devices and polymers. These volumes are written by leading international experts and cover all possible aspects of green solvents’ properties and applications available in today’s literature. Green Solvents Volume I and II is an invaluable guide to scientists, R&D industrial specialists, researchers, upper-level undergraduates and graduate students, Ph.D. scholars, college and university professors working in the field of chemistry and biochemistry.
Author: Aditya Bansal
Author: Aditya Bansal
Author: Christian David Martinez
Author: Vincenzo Bianco
Author: Javier Artemio Narvaez Bazan
Author: Aditya Kumar
Author: Johnathan Stuart Coursey
Author: Li, Changhe
Author: Bharat Bhanvase
Author: G. M. Carlomagno
Author: Ali Mohammad