Nanofluids: From Vision to Reality Through Research

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Stephen U. S. Choi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Future Directions ◽  
Fundamental Limits ◽  
Heat Transfer Fluids ◽  
Size Dependent ◽  
New Class ◽  
Scientists And Engineers ◽  
Basic And Applied Research

Nanofluids are a new class of nanotechnology-based heat transfer fluids engineered by dispersing and stably suspending nanoparticles with typical length on the order of 1–50 nm in traditional heat transfer fluids. For the past decade, pioneering scientists and engineers have made phenomenal discoveries that a very small amount (<1 vol %) of guest nanoparticles can provide dramatic improvements in the thermal properties of the host fluids. For example, some nanofluids exhibit superior thermal properties such as anomalously high thermal conductivity at low nanoparticle concentrations, strong temperature- and size-dependent thermal conductivity, a nonlinear relationship between thermal conductivity and concentration, and a threefold increase in the critical heat flux at a small particle concentration of the order of 10 ppm. Nanofluids are of great scientific interest because these unprecedented thermal transport phenomena surpass the fundamental limits of conventional macroscopic theories of suspensions. Therefore, numerous mechanisms and models have been proposed to account for these unexpected, intriguing thermal properties of nanofluids. These discoveries also show that nanofluids technology can provide exciting new opportunities to develop nanotechnology-based coolants for a variety of innovative engineering and medical applications. As a result, the study of nanofluids has emerged as a new field of scientific research and innovative applications. Hence, the subject of nanofluids is of great interest worldwide for basic and applied research. This paper highlights recent advances in this new field of research and shows future directions in nanofluids research through which the vision of nanofluids can be turned into reality.

scholarly journals Critical Review on Nanofluids: Preparation, Characterization, and Applications

2016 ◽  
Vol 2016 ◽  
pp. 1-22 ◽  
Author(s):  
Mohamoud Jama ◽  
Tejvir Singh ◽  
Seifelislam Mahmoud Gamaleldin ◽  
Muammer Koc ◽  
Ayman Samara ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
High Performance ◽  
Two Phase ◽  
Heat Transfer Fluids ◽  
Thermal And Electrical Properties ◽  
Improve Heat Transfer ◽  
The Stability ◽  
New Generation

Heat transfer fluids are a crucial parameter that affects the size and costs of heat exchangers. However, the available coolants like water and oils have low thermal conductivities, which put many limitations to the development of heat transfer to achieve high performance cooling. The need for development of new classes of fluids which enhance the heat transfer capabilities attracted the attention of many researchers. In the last few decades, modern nanotechnology developed nanoparticles, which have unique thermal and electrical properties that could help improve heat transfer using nanofluids. A “nanofluid” is a fluid with suspended fine nanoparticles which increases the heat transfer properties compared with the original fluid. Nanofluids are considered a new generation of heat transfer fluids and are considered two-phase fluids of liquid solid mixtures. The efficiency of the fluid could be improved by enhancing its thermal properties, especially the thermal conductivity, and it is expected that the nanofluids will have a greater thermal conductivity than the base fluids. This paper reviews the preparation of metallic and nonmetallic nanofluids along with the stability of the produced nanofluids. Physical and thermal properties as well as a range of applications are also discussed in detail.

scholarly journals Enhanced Thermal Conductivity through the Development of Nanofluids

1996 ◽  
Vol 457 ◽  
Author(s):  
J. A. Eastman ◽  
U. S. Choi ◽  
S. Li ◽  
L. J. Thompson ◽  
S. Lee
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Industrial Applications ◽  
Nano Particles ◽  
Nanocrystalline Powder ◽  
Heat Transfer Fluids ◽  
New Class ◽  
Nanocrystalline Particles ◽  
Oxide Particles ◽  
Efficient Heat Transfer

ABSTRACTLow thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids required in many industrial applications. To overcome this limitation, a new class of heat transfer fluids is being developed by suspending nanocry stalline particles in liquids such as water or oil. The resulting “nanofluids” possess extremely high thermal conductivities compared to the liquids without dispersed nanocrystalline particles. For example, 5 volume % of nanocrystalline copper oxide particles suspended in water results in an improvement in thermal conductivity of almost 60% compared to water without nanoparticles. Excellent suspension properties are also observed, with no significant settling of nanocrystalline oxide particles occurring in stationary fluids over time periods longer than several days. Direct evaporation of Cu nano-particles into pump oil results in similar improvements in thermal conductivity compared to oxide-in-water systems, but importantly, requires far smaller concentrations of dispersed nanocrystalline powder.

A Brief Review on Thermal Behaviour of PANI as Additive in Heat Transfer Fluid

2021 ◽  
Vol 02 (01) ◽  
Author(s):  
A.G.N. Sofiah ◽  
◽  
M. Samykano ◽  
S. Shahabuddin ◽  
K. Kadirgama ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Conducting Polymers ◽  
Volume Fraction ◽  
Corrosion Property ◽  
Environmental Stability ◽  
Heat Transfer Fluid ◽  
Thermal Engineering ◽  
Engineering System ◽  
Heat Transfer Fluids

Since a decade ago, investigation on nanofluids has grown significantly owing to its enhanced thermal properties compared to conventional heat transfer fluids. This engineered nanofluid has been widely used in the thermal engineering system to improve their energy consumption by improving the thermal efficiency of the system. The addition of nano-size particles as additives dispersed in the base fluids proved to significantly either improve or diminish the behaviour of the base fluids. The behaviour of the base fluid highly depends on the properties of the additives material, such as morphology, size, and volume fraction. Among the variety of nanoparticles studied, the conducting polymers have been subject of high interest due to its high environmental stability, good electrical conductivity, antimicrobial, anti-corrosion property and significantly cheap compared to other nanoparticles. As such, the main objective of the present review is to provide an overview of the work performed on thermal properties performance of conducting polymers based nanofluids.

Study of thermal conductivity of nanofluids for the application of heat transfer fluids

2007 ◽  
Vol 455 (1-2) ◽  
pp. 66-69 ◽  
Author(s):  
Dae-Hwang Yoo ◽  
K.S. Hong ◽  
Ho-Soon Yang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Fluids

Heat Exchange Between a Tube and Water-Saturated Soil

1986 ◽  
Vol 108 (4) ◽  
pp. 298-302 ◽  
Author(s):  
C. A. van der Star ◽  
G. A. M. van Meurs ◽  
C. J. Hoogendoorn
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Saturated Soil ◽  
Mutual Distance ◽  
Tube Material ◽  
Surrounding Water ◽  
Analytical Approximations ◽  
Water Saturated ◽  
Regional Groundwater

The heat transfer between a cylinder and the surrounding water-saturated soil is studied numerically. Parameters which influence this heat transfer are thermal properties of the soil, dimension and thermal conductivity of the tube material, and a regional groundwater flow. The results are compared to analytical approximations. When two tubes are present, their mutual distance is also such a parameter.

Heat Transfer Properties of Engine Oils

2005 ◽  
Author(s):  
Scott Wrenick ◽  
Paul Sutor ◽  
Harold Pangilinan ◽  
Ernest E. Schwarz
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Diesel Engine ◽  
Specific Heat ◽  
Mineral Oil ◽  
Engine Oil ◽  
Group V ◽  
Engine Oils ◽  
Heat Transfer Fluids ◽  
Transfer Properties

The thermal properties of engine oil are important traits affecting the ability of the oil to transfer heat from the engine. The larger the thermal conductivity and specific heat, the more efficiently the oil will transfer heat. In this work, we measured the thermal conductivity and specific heat of a conventional mineral oil-based diesel engine lubricant and a Group V-based LHR diesel engine lubricant as a function of temperature. We also measured the specific heat of ethylene glycol. The measured values are compared with manufacturers’ data for typical heat transfer fluids. The Group V-based engine oil had a higher thermal conductivity and slightly lower specific heat than the mineral oil-based engine oil. Both engine oils had values comparable to high-temperature heat transfer fluids.

scholarly journals Measurement of Thermal Conductivity along the Radial Direction in a Vertical Cylindrical Packed Bed

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Swaren Bedarkar ◽  
Nurni Neelakantan Viswanathan ◽  
Nidambur Bharatha Ballal
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Crucial Role ◽  
Iron Ore ◽  
Radial Direction ◽  
Thermal Response ◽  
Packed Bed ◽  
Lumped Parameter ◽  
Scientists And Engineers

Heat transfer in packed beds and their thermal response have been of great interest for scientists and engineers for the last several years, since they play a crucial role in determining design and operation of reactors. Heat transfer of a packed bed is characterised through lumped parameter, namely, effective thermal conductivity. In the present studies, experiments were performed to investigate the thermal conductivity of a packed bed in radial direction. The packed bed was formed using iron ore particles. To determine the effective thermal conductivity a new transient methodology is proposed. The results obtained were compared with the models proposed by ZBS and Kunii and Smith.

Analysis of nanofluids as a means of thermal conductivity enhancement in heavy machineries

2014 ◽  
Vol 66 (2) ◽  
pp. 238-243 ◽  
Author(s):  
Ayush Jain ◽  
Imbesat Hassan Rizvi ◽  
Subrata Kumar Ghosh ◽  
P.S. Mukherjee
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Ethylene Glycol ◽  
Base Fluid ◽  
High Concentration ◽  
Content Type ◽  
Conductivity Enhancement ◽  
Heavy Machinery ◽  
Heat Transfer Fluids ◽  
Experimental Findings

Purpose – Nanofluids exhibit enhanced heat transfer characteristics and are expected to be the future heat transfer fluids particularly the lubricants and transmission fluids used in heavy machinery. For studying the heat transfer behaviour of the nanofluids, precise values of their thermal conductivity are required. For predicting the correct value of thermal conductivity of a nanofluid, mathematical models are necessary. In this paper, the effective thermal conductivity of various nanofluids has been reported by using both experimental and mathematical modelling. The paper aims to discuss these issues. Design/methodology/approach – Hamilton and Crosser equation was used for predicting the thermal conductivities of nanofluids, and the obtained values were compared with the experimental findings. Nanofluid studied in this paper are Al2O3 in base fluid water, Al2O3 in base fluid ethylene glycol, CuO in base fluid water, CuO in base fluid ethylene glycol, TiO2 in base fluid ethylene glycol. In addition, studies have been made on nanofluids with CuO and Al2O3 in base fluid SAE 30 particularly for heavy machinery applications. Findings – The study shows that increase in thermal conductivity of the nanofluid with particle concentration is in good agreement with that predicted by Hamilton and Crosser at typical lower concentrations. Research limitations/implications – It has been observed that deviation between experimental and theoretical results increases as the volume concentration of nanoparticles increases. Therefore, the mathematical model cannot be used for predicting thermal conductivity at high concentration values. Originality/value – Studies on nanoparticles with a standard mineral oil as base fluid have not been considered extensively as per the previous literatures available.

Thermal Conductivity and Specific Heat Evaluation of Tissue Using Laser

2020 ◽  
Vol 1002 ◽  
pp. 303-310
Author(s):  
Sudad Issam Younis ◽  
Haqi I. Qatta ◽  
Mohammed Jalal Abdul Razzaq ◽  
Khalid S. Shibib
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Iterative Procedure ◽  
Input Data ◽  
Maximum Error ◽  
Heat Transfer Analysis ◽  
Long Wavelength ◽  
Inverse Heat Transfer

In this work, an inverse heat transfer analysis was used to determine thermal conductivity and specific heat of tissue using special iteration. A laser with a long wavelength was utilized to impose heat to the tissue. The heat that induced in the sample causes an increase in the temperature of a tissue which is measured by a thermocouple. The readings were used together with that analytically obtained from the solution of the heat equation in an iterative procedure to obtain the thermal properties of tissue. By using this method, accurate thermal conductivity and specific heat of tissue could be obtained. It was found that the maximum error in output result and the error in input data were in the same order and that there was a linear relationship between output and input errors.

A Self-Heated Thermistor Technique to Measure Effective Thermal Properties From the Tissue Surface

1987 ◽  
Vol 109 (4) ◽  
pp. 330-335 ◽  
Author(s):  
P. A. Patel ◽  
J. W. Valvano ◽  
J. A. Pearce ◽  
S. A. Prahl ◽  
C. R. Denham
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Tissue Blood Flow ◽  
Conductivity Measurements ◽  
Bioheat Equation ◽  
Tissue Conductivity ◽  
Diffusivity Measurements ◽  
Tissue Surface ◽  
Effective Thermal Properties

A microcomputer based instrument to measure effective thermal conductivity and diffusivity at the surface of a tissue has been developed. Self-heated spherical thermistors, partially embedded in an insulator, are used to simultaneously heat tissue and measure the resulting temperature rise. The temperature increase of the thermistor for a given applied power is a function of the combined thermal properties of the insulator, the thermistor, and the tissue. Once the probe is calibrated, the instrument accurately measures the thermal properties of tissue. Conductivity measurements are accurate to 2 percent and diffusivity measurements are accurate to 4 percent. A simplified bioheat equation is used which assumes the effective tissue thermal conductivity is a linear function of perfusion. Since tissue blood flow strongly affects heat transfer, the surface thermistor probe is quite sensitive to perfusion.

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