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An investigation of thermal performance improvement of a cylindrical heat pipe using Al2O3 nanofluid
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
2016 (English)In: Heat and Mass Transfer, ISSN 0947-7411, E-ISSN 1432-1181, 1-11 p.Article in journal (Refereed) Published
Abstract [en]

In this study, effect of Al2O3 nanofluid on thermal performance of cylindrical heat pipe is investigated. An analytical model is employed to study the thermal performance of the heat pipe utilizing nanofluid and the predicted results are compared with the experimental results. A substantial change in the heat pipe thermal resistance, effective thermal conductivity and entropy generation of the heat pipe is observed when using Al2O3 nanofluid as a working fluid. It is found that entropy generation in the heat pipe system decreases when using a nanofluid due to the lower thermal resistance of the heat pipe which results in an improved thermal performance. It is shown that the proposed model is in reasonably good agreement with the experimental results and can be used as a fast technique to explore various features of thermal characteristics of the nanofluid based heat pipe.

Place, publisher, year, edition, pages
Springer, 2016. 1-11 p.
Keyword [en]
Aluminum, Entropy, Heat resistance, Nanofluidics, Thermal conductivity, Effective thermal conductivity, Entropy generation, Fast techniques, Nanofluids, Pipe system, Thermal characteristics, Thermal Performance, Working fluid, Heat pipes
National Category
Energy Engineering
Identifiers
URN: urn:nbn:se:kth:diva-197123DOI: 10.1007/s00231-016-1871-9ScopusID: 2-s2.0-84979240852OAI: oai:DiVA.org:kth-197123DiVA: diva2:1056260
Note

QC 20161214

Available from: 2016-12-14 Created: 2016-11-30 Last updated: 2017-03-02Bibliographically 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. 103 p.
Series
TRITA-REFR, ISSN 1102-0245 ; 17/01
Keyword
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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