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Thermal properties and rheological behavior of water based Al2O3 nanofluid as a heat transfer fluid
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
2014 (English)In: Experimental Thermal and Fluid Science, ISSN 0894-1777, E-ISSN 1879-2286, Vol. 53, p. 227-235Article in journal (Refereed) Published
Abstract [en]

An experimental investigation and theoretical study of thermal conductivity and viscosity of Al2O3/water nanofluids are presented in this article. Various suspensions containing Al2O3 nanoparticles were tested in concentration ranging from 3% to 50% in mass and temperature ranging from 293K to 323K. The results reveal that both the thermal conductivity and viscosity of nanofluids increase with temperature and particle concentration accordingly while the increase in viscosity is much higher than the increase in thermal conductivity. The thermal conductivity and viscosity enhancement are in the range of 1.1-87% and 18.1-300%, respectively. Moreover, the results indicate that the thermal conductivity increases nonlinearly with concentration, but, linearly with the increase in temperature. In addition, the experimental results are compared with some existing correlations from literature and some modifications are suggested. Finally, the average heat transfer coefficient at different basis of comparisons including equal Reynolds number, fluid velocity and pumping power is studied based on the experimental thermal conductivity and viscosity in fully developed laminar and turbulent flow regimes. It is found that equal Reynolds number as a basis of comparison is highly misleading and equal pumping power can be used to study the advantage of using nanofluid instead of the base fluid.

Place, publisher, year, edition, pages
2014. Vol. 53, p. 227-235
Keywords [en]
Al2O3 nanoparticle, Heat transfer, Nanofluid, Thermal conductivity, Viscosity
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:kth:diva-142818DOI: 10.1016/j.expthermflusci.2013.12.013ISI: 000331422700025Scopus ID: 2-s2.0-84892546097OAI: oai:DiVA.org:kth-142818DiVA, id: diva2:704437
Note

QC 20140312

Available from: 2014-03-12 Created: 2014-03-12 Last updated: 2017-12-05Bibliographically approved
In thesis
1. Investigation of Thermal Performance of Cylindrical Heatpipes Operated with Nanofluids
Open this publication in new window or tab >>Investigation of Thermal Performance of Cylindrical Heatpipes Operated with Nanofluids
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanofluids as an innovative class of heat transfer fluids created by dispersing nanometre-sizedmetallic or non-metallic particles in conventional heat transfer fluids displayed the potential toimprove the thermophysical properties of the heat transfer fluids. The main purpose of this study is toinvestigate the influence of the use of nanofluids on two-phase heat transfer, particularly on thethermal performance of the heat pipes. In the first stage, the properties of the nanofluids were studied,then, these nanofluids were used as the working fluids of the heat pipes. The thermal performance ofthe heat pipes when using different nanofluids was investigated under different operating conditionsexperimentally and analytically. The influences of the concentration of the nanofluids, inclinationangles and heat loads on the thermal performance and maximum heat flux of the heat pipes wereinvestigated.This study shows that the thermal performance of the heat pipes depends not only on thermophysicalproperties of the nanofluids but also on the characteristics of the wick structure through forming aporous coated layer on the heated surface. Forming the porous layer on the surface of the wick at theevaporator section increases the wettability and capillarity and also the heat transfer area at theevaporator of the heat pipes.The thermal performance of the heat pipes increases with increasing particle concentration in all cases,except for the heat pipe using 10 wt.% water/Al2O3 nanofluid. For the inclined heat pipe, irrespectiveof the type of the fluid used as the working fluid, the thermal resistance of the inclined heat pipes waslower than that of the heat pipes in a horizontal state, and the best performance was observed at theinclination angle of 60o, which is in agreement with the results reported in the literature. Otheradvantages of the use of nanofluids as the working fluids of the heat pipes which were investigated inthis study were the increase of the maximum heat flux and also the reduction of the entropy generationof the heat pipes when using a nanofluid.These findings revealed the potential for nanofluids to be used instead of conventional fluids as theworking fluid of the heat pipes, but the commercialization of the heat pipes using nanofluids for largescale industrial applications is still a challenging question, as there are many parameters related to thenanofluids which are not well understood.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. p. 103
Series
TRITA-REFR, ISSN 1102-0245 ; 17/01
Keywords
Nanofluid, heat pipe, thermal resistance, heat transfer coefficient, evaporator, condenser, wick, porous layer, heat flux, inclination angle, thermal conductivity, viscosity
National Category
Engineering and Technology
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-202566 (URN)978-91-7729-291-3 (ISBN)
Public defence
2017-03-17, F3, Lindstedtsvägen 26, Stockholm, 14:00 (English)
Opponent
Supervisors
Note

QC 20170228

Available from: 2017-02-28 Created: 2017-02-28 Last updated: 2017-03-01Bibliographically approved

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