An Experimental Investigation of Properties of Nanofluid and Its Performance on Thermosyphon Cooled by Natural Convection

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Sidhartha Das ◽  
Asis Giri ◽  
S. Samanta ◽  
S. Kanagaraj
Keyword(s):  
Thermal Conductivity ◽  
Surface Tension ◽  
Contact Angle ◽  
Experimental Investigation ◽  
Natural Convection ◽  
Thermal Resistance ◽  
Al2o3 Nanoparticles ◽  
Water Based ◽  
Lower Heat ◽  
Al2o3 Nanofluid

An attempt is made here to characterize thermal conductivity of water-based Al2O3 nanofluid and then use the same in a circular finned thermosyphon (TPCT) to measure its thermal performance. The concentration of Al2O3 nanofluid is varied within 0.05–0.25% by volume. The thermal conductivity of nanofluid is increased with concentration of Al2O3 nanoparticles as well as with temperature. A maximum of 26.7% enhancement of thermal conductivity is observed at 45 °C for 0.25% concentration by volume of nanofluid in comparison to that of de-ionized (DI) water. Variations of surface tension and contact angle of Al2O3 nanofluid are also compared with DI water. One of the smallest TPCT with different heat inputs (4 W, 8 W, and 12 W) and different inclinations (30 deg, 45 deg, 60 deg, and 90 deg) is tested for different concentration of Al2O3 nanofluid, which will find application in smaller electronic units. It is found that use of nanofluid decreases the wall temperature distribution of TPCT. Thermal resistance of TPCT decreases whenever TPCT is filled with nanofluid and a maximum of 36.4% reduction in thermal resistance is noted for 0.25% volume of nanoparticles at 4 W with an inclination of 60 deg. It is also found that performance of TPCT is higher at 60 deg inclination compared to other inclinations, especially for lower heat input.

Experimental Investigation on Surface Tension of Water-Based Graphene Oxide Nanofluids

2014 ◽  
Vol 1082 ◽  
pp. 297-301 ◽  
Author(s):  
Zhao Zhi Zheng
Keyword(s):  
Surface Tension ◽  
Experimental Investigation ◽  
Graphene Oxide ◽  
Mass Fraction ◽  
Deionized Water ◽  
Nanoparticle Size ◽  
Refrigeration Cycle ◽  
Absorption Refrigeration ◽  
Water Based ◽  
Increasing Temperature

The water-based graphene oxide nanofluids were prepared. The surface tension of nanofluids with different mass fraction, temperature and different nanoparticle size was researched. The surface tension value was measured through ringmethod. The experimental results show that the surface tension of nanofluids is increased with increasing the mass faction of nanoparticles. But the surface tension of nanofluids with maximum concentration (0.1 wt %) is only increased up to 2.9% compared with deionized water. The surface tension of nanofluids decreases with increasing temperature and decreasing nanoparticle size. The results of this paper may provide reference for the research of absorption liquid for absorption refrigeration cycle.

Experimental investigation on thermal conductivity of water based nickel ferrite nanofluids

2015 ◽  
Vol 26 (6) ◽  
pp. 1529-1536 ◽  
Author(s):  
Amir Karimi ◽  
Mohamad Amin Abdolahi Sadatlu ◽  
Behzad Saberi ◽  
Hamed Shariatmadar ◽  
Mehdi Ashjaee
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Nickel Ferrite ◽  
Water Based

Investigation on the Use of Nanofluids to Enhance Heat Pipe Performance

Solar Energy ◽  
2005 ◽  
Author(s):  
Tomer Israeli ◽  
T. Agami Reddy ◽  
Young I. Cho
Keyword(s):  
Thermal Conductivity ◽  
Surface Tension ◽  
Thermal Resistance ◽  
Copper Oxide ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Experimental Studies ◽  
Heat Pipes ◽  
Thermal Network ◽  
Overall Resistance

This paper reports on preliminary experimental results on using nanofluids to enhance the thermal performance of heat pipes. Our experience with preparing copper oxide (CuO) nanofluids is described. Contrary to earlier studies which report infinite shelf life, we found that nanofluid stability lasted for about three weeks only; an issue which merits further study. We have also conducted various experiments to measure the variation of thermal conductivity and surface tension with CuO nanofluid concentration. Actual experiments on nanofluid heat pipes were also performed which indicated an average 12.5% decrease in the overall thermal resistance of the heat pipe using nanofluid of 3% vol concentration. This observed improvement is fairly consistent with our predictions using a simple analytical thermal network model for heat pipe overall resistance and the measured nanofluid conductivity. The results, though encouraging, need more careful and elaborate experimental studies before the evidence can be deemed conclusive.

Compact Thermal Representations for Several Fundamental Shapes in Natural Convection

2003 ◽  
Author(s):  
Kyle A. Brucker ◽  
Kyle T. Ressler ◽  
Joseph Majdalani
Keyword(s):  
Thermal Conductivity ◽  
Natural Convection ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Heat Sink ◽  
Volume Of Fluid ◽  
Compact Representation ◽  
Canonical Forms ◽  
Design Engineers ◽  
Porous Block

In this article, general canonical forms for the effective thermal conductivities of compact heat sink models are derived using perturbation tools. The resulting approximations apply to a large number of fundamental heat sink shapes used in natural convection applications. The effective thermal conductivity is a property that can be assigned to the porous block (i.e., volume of fluid) above the heat sink base that was once occupied by the fins. The increased thermal conductivity of the fluid entering the porous block produces a reduced thermal resistance that matches that of the original heat sink. The use of a compact representation is accompanied by substantial computational savings that promote faster optimization and communication between simulation analysts and design engineers. The generalized approximations for the effective thermal conductivity presented here are numerically verified.

scholarly journals Experimental study on the influence of coal powders on the performance of water-based polymer drilling fluid

2020 ◽  
Vol 38 (5) ◽  
pp. 1515-1534
Author(s):  
Lei Zhang ◽  
Xiaoming Wu ◽  
Shuaifeng Lyu ◽  
Penglei Shen ◽  
Lulu Liu ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Coalbed Methane ◽  
Drilling Fluid ◽  
Wellbore Stability ◽  
Filtration Loss ◽  
Water Based ◽  
Natural Degradation ◽  
Tension Increase ◽  
Powder Content

Coal powders, as cuttings, invade the drilling fluid along a coal seam during coalbed methane development, thereby changing the properties of the drilling fluid. Therefore, this work aims to investigate the influence of coal powders on drilling fluid performance. The powders of lignite, anthracite, and contrasting shale were added to a water-based polymer drilling fluid. Then, the rheology, filtration, lubricity, and adhesiveness were measured, and the natural degradation, as well as the wettability were further evaluated. The results show that some parameters of the drilling fluid, including viscosity, lubrication coefficient, adhesion coefficient, contact angle, and surface tension, increase after adding coal powders, while other parameters, such as filtration loss and natural degradation, decrease. Compared with lignite and shale, anthracite powders, with the lowest mineral content, exhibit the smallest change in the rheological property, lubricity, adhesion, and natural degradation of the drilling fluid. Moreover, the content and size of the coal powders generally have opposing effects on the drilling fluid. When the coal powder content reaches 3 wt.%, the surface tension and contact angle of the drilling fluid show more evident changes than other parameters. Based on the analysis of the stress intensity factor, the drilling fluid with coal powders exceeding 100 mesh can reduce the capillary force in microfractures, and in combination with other factors (such as reduced filtration loss and sealing and supporting of the microfractures), improves wellbore stability. Therefore, coal powders with suitable particle sizes and concentration levels are expected to become a new drilling fluid material to protect coal field reservoirs.

Experimental Investigation of Magnetically-Induced Thermal Conductance Variations in a Ferromagnetic Nanofluid

2011 ◽  
Author(s):  
Alexander M. Gardner ◽  
Indira Seshadri ◽  
Ganpati Ramanath ◽  
Theodorian Borca-Tasciuc
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Magnetic Fields ◽  
Thermal Resistance ◽  
Applied Magnetic Field ◽  
Thermal Conductance ◽  
Flow Characteristics ◽  
Test Apparatus ◽  
The Subject

Ferrofluids have been the subject of great interest in engineering because of their unique flow characteristics under magnetic fields (Rosensweig, 1987). However, there are limited experiments which show the potential of ferrofluids to undergo controlled changes in thermal conductivity (Philip et al., 2008) under magnetic fields. The purpose of this experiment is to investigate thermal transport in ferrofluids. A test apparatus was designed and the thermal resistance of a commercially available ferromagnetic fluid within a test cell was measured as a function of the applied magnetic field.

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