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The effect of nanoparticles on laminar heat transfer in a horizontal tube
KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
Visa övriga samt affilieringar
2014 (Engelska)Ingår i: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 69, s. 77-91Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Heat transfer coefficient in laminar flow of water-based alumina, titania and carbon nanotube nanofluids in a straight pipe with constant heat flux at the wall have been investigated independently by two universities. The nanoparticles affect the thermo-physical properties of the suspensions, however, nanopartides presence and movement due to Brownian diffusion and thermophoresis seemed to have insignificant effect on heat transfer coefficient. The Nusselt number of all investigated nanofluids followed standard heat transfer correlations developed for liquids within +/- 10% suggesting that all investigated nanofluids can be treated as homogenous fluids. Different methods of comparison between heat transfer coefficient in nanofluids and base fluid are also critically discussed.

Ort, förlag, år, upplaga, sidor
2014. Vol. 69, s. 77-91
Nyckelord [en]
Nanofluid, Heat transfer coefficient, Laminar flow
Nationell ämneskategori
Energiteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-141055DOI: 10.1016/j.ijheatmasstransfer.2013.10.003ISI: 000329552900009Scopus ID: 2-s2.0-84887105815OAI: oai:DiVA.org:kth-141055DiVA, id: diva2:695696
Forskningsfinansiär
EU, FP7, Sjunde ramprogrammet, NMP-2008-1.2-1
Anmärkning

QC 20140212

Tillgänglig från: 2014-02-12 Skapad: 2014-02-07 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
Ingår i avhandling
1. Single Phase Convective Heat Transfer with Nanofluids: An Experimental Approach
Öppna denna publikation i ny flik eller fönster >>Single Phase Convective Heat Transfer with Nanofluids: An Experimental Approach
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Nanofluids (NFs) are engineered colloids of nanoparticles (NPs) dispersed homogenously within base fluids (BFs). Due to the presence of NPs, the thermophysical and transport properties of BFs are subject to change. Existing technologies for cooling electronics seem to be insufficient and NFs, as reported in several studies, might offer a better alternative to liquid cooling. The main purpose of this study, by choosing a critical approach to existing knowledge in the literature, is to investigate experimentally the potential for replacing BFs with NFs in single–phase flow. Several NFs (mainly water based metal oxide NFs) were synthesised, and different experiments (including thermal conductivity, viscosity, heat transfer coefficient, and shelf stability) were performed.

The thermal conductivity and the viscosity of several NFs were measured at both near room and elevated temperatures; the results are reported and compared with some correlations. It is shown that the Maxwell model for thermal conductivity and the modified Krieger–Dougherty model for viscosity can be used to predict these properties of NFs within ±10% error, even at elevated temperatures.

A screening setup, including a test section with d = 0.5 mm and L = 30 cm, was designed for measuring the heat transfer performance of NFs in laminar flow. In addition a closed–loop setup with a 3.7 mm inner diameter and 1.5 m length test section was also designed to measure the heat transfer coefficients in both laminar and turbulent flow with higher accuracy. Based on the results, classical correlations for predicting Nusselt number and friction factor in a straight tube are still valid for NFs within ± (10 – 20)% error provided that the correct thermophysical properties are used for NFs.

Different methods of comparing cooling performance of NFs to BFs are then investigated. Comparison at equal Reynolds number, the most popular method in the literature, is demonstrated both experimentally and analytically to be misleading. However, if the most correct criterion (at equal pumping power) is chosen, a small advantage for some NFs over their BFs should be expected only under laminar flow. The investigation concludes with the proposition of a unique method and apparatus to estimate the shelf stability of NFs.

Abstract [sv]

Nanofluider (NF) kallas suspensioner av nanopartiklar (NP) i en vätska (base fluid, BF). Tillsatsen av nanopartiklar leder till förändring av vätskans termodynamiska- och transport-egenskaper vilket eventuellt kan utnyttjas för att anpassa egenskaperna efter speciella behov.

Befintliga teknologier för kylning av elektronik tenderar att vara otillräckliga och nanofluider kan, som föreslagits i olika studier, ge en möjlighet att åstadkomma effektivare vätskekylning än dagens kylmedier. Huvudsyftet med denna studie har varit att kritiskt granska tidigare publicerad information om nanofluider samt att genom nya tester av många olika nanofluider undersöka potentialen för att ersätta vanligt förekommande kylvätskor med nanofluider i tillämpningar utan fasändring. Ett stort antal nanofluider, huvudsakligen vattenbaserade metall-oxid nanofluider, karakteriserades genom bestämning av värmeledningstal, viskositet, värmeövergångstal vid rörströmning och möjlig lagringstid. De experimentella resultaten analyseras i detalj och jämförs med korrelationer från litteraturen.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2015. s. x, 116
Serie
TRITA-REFR, ISSN 1102-0245 ; 15:01
Nyckelord
nanofluid, convective heat transfer, thermal conductivity, viscosity, heat transfer coefficient, performance, pumping power, Reynolds number, shelf stability
Nationell ämneskategori
Energiteknik
Identifikatorer
urn:nbn:se:kth:diva-159199 (URN)978-91-7595-414-1 (ISBN)
Disputation
2015-02-05, Sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20150126

Tillgänglig från: 2015-01-26 Skapad: 2015-01-23 Senast uppdaterad: 2019-12-09Bibliografiskt granskad

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Palm, Björn

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Haghighi, Ehsan B.Ghanbarpourgeravi, MortezaKhodabandeh, RahmatollahPalm, Björn
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Tillämpad termodynamik och kylteknikEnergiteknik
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