| 1. |
- Ahangar Zonouzi, S., et al.
(författare)
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Experimental investigation of the flow and heat transfer of magnetic nanofluid in a vertical tube in the presence of magnetic quadrupole field
- 2018
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Ingår i: Experimental Thermal and Fluid Science. - : Elsevier. - 0894-1777 .- 1879-2286. ; 91, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the effects of applying magnetic field on hydrodynamics and heat transfer of Fe3O4/water magnetic nanofluid flowing inside a vertical tube have been studied experimentally. The applied magnetic field was resulted from quadrupole magnets located at different axial positions along the tube length. The variations of the local heat transfer coefficient and also the pressure drop of the ferrofluid flow along the length of the tube by applying the magnetic quadrupole field have been investigated for different Reynolds numbers. The obtained experimental results show maximum enhancements of 23.4%, 37.9% and 48.9% in the local heat transfer coefficient for the magnetic nanofluid with 2 vol% Fe3O4 in the presence of the quadrupole magnets located at three different axial installation positions for the Reynolds number of 580 and the relative increase in total pressure drop by applying the magnetic field is about 1% for Re = 580. The increase of the heat transfer coefficient is due to the radial magnetic force toward the heated wall generated by magnetic quadrupole field acting over the ferrofluid flowing inside the tube so that the velocity of the ferrofluid in the vicinity of the heated wall is increased. It is also observed that the enhancement of heat transfer coefficient by applying magnetic quadrupole is decreased with increasing the Reynolds number.
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| 2. |
- Ahangar Zonouzi, S., et al.
(författare)
-
Experimental study of the subcooled flow boiling heat transfer of magnetic nanofluid in a vertical tube under magnetic field
- 2020
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer. - 1388-6150 .- 1588-2926. ; 140:6, s. 2805-2816
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the subcooled boiling heat transfer of a Fe3O4/water magnetic nanofluid flowing through a vertical tube has been investigated experimentally in the presence and absence of a magnetic field. The magnetic field has been generated by quadrupole magnets. The subcooled boiling heat transfer coefficient and the boiling curves of the ferrofluid flow under the action of the magnetic field have been compared with those in the absence of magnetic field. The results showed that magnetic actuation contributes to have higher heat fluxes at the same wall superheat in comparison with heat fluxes achieved in the no magnetic field case. Therefore, the local subcooled boiling heat transfer coefficients are increased by the magnetic field. The maximum measured enhancement in local subcooled boiling heat transfer coefficient along the length of the tube by applying magnetic field is 46.58% at applied heat flux of 77,000 W m−2 and mass flux of 270 kg m−2 s−1. Furthermore, the enhancement of local heat transfer coefficient by applying magnetic field decreases as the applied heat flux in the subcooled boiling region is increased.
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| 3. |
- Becker, Julia K., et al.
(författare)
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Tracing the sources of cosmic rays with molecular ions
- 2011
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Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 739:October 1, s. L43 (5 pages)-
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Tidskriftsartikel (refereegranskat)abstract
- The rate of ionization by cosmic rays (CRs) in interstellar gas directly associated with γ-ray-emitting supernova remnants (SNRs) is for the first time calculated to be several orders of magnitude larger than the Galactic average. Analysis of ionization-induced chemistry yields the first quantitative prediction of the astrophysical H2+ emission line spectrum, which should be detectable together with H3+ lines. The predicted coincident observation of those emission lines and γ-rays will help prove that SNRs are sources of CRs.
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