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Noori Rahim Abadi, Seyyed Mohammad AliORCID iD iconorcid.org/0000-0002-6102-9021
Publications (2 of 2) Show all publications
Torkfar, A., Noori Rahim Abadi, S. M. & Ahmadpour, A. (2020). Natural Convection Heat Transfer of Non-Newtonian Power-Law Fluids Within an Array of Elliptic Cylinders. Journal of Fluids Engineering - Trancactions of The ASME, 142(1), Article ID 011105.
Open this publication in new window or tab >>Natural Convection Heat Transfer of Non-Newtonian Power-Law Fluids Within an Array of Elliptic Cylinders
2020 (English)In: Journal of Fluids Engineering - Trancactions of The ASME, ISSN 0098-2202, E-ISSN 1528-901X, Vol. 142, no 1, article id 011105Article in journal (Refereed) Published
Abstract [en]

In this study, natural convection of non-Newtonian power-law fluids around an array of elliptic cylinders has been investigated numerically. The governing equations have been solved using an in-house computational fluid dynamics code based on the well-known finite volume method. It is assumed that the flow and temperature fields are laminar, steady, and two-dimensional. Furthermore, due to the low-temperature difference between the tube walls and the surrounding fluid, the changes in the physical properties of the fluids are neglected. The numerical results are validated against the available experimental and numerical results. The results show that by increasing the non-Newtonian fluid power-law index, the ratio of average Nusselt number of the ith cylinder to the average Nusselt number of a single cylinder under identical thermal conditions decreases. Moreover, it is found that the increase in the ratio of the distance between elliptic centers and the elliptic vertical diameter increases the ratio of the average Nusselt number of ith cylinder to the average Nusselt number for a single cylinder. Finally, a mathematical expression is given for the array averaged Nusselt number.

Keywords
natural convection; non-Newtonian fluid; elliptic cylinders; power-law index
National Category
Energy Engineering
Identifiers
urn:nbn:se:hv:diva-15120 (URN)10.1115/1.4044630 (DOI)000522560400016 ()
Available from: 2020-04-16 Created: 2020-04-16 Last updated: 2020-04-16
Ahmadpour, A. & Noori Rahim Abadi, S. M. (2019). Thermal-hydraulic performance evaluation of gas-liquid multiphase flows in a vertical sinusoidal wavy channel in the presence/absence of phase change. International Journal of Heat and Mass Transfer, 138, 677-689
Open this publication in new window or tab >>Thermal-hydraulic performance evaluation of gas-liquid multiphase flows in a vertical sinusoidal wavy channel in the presence/absence of phase change
2019 (English)In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 138, p. 677-689Article in journal (Refereed) Published
Abstract [en]

Turbulent gas-liquid multiphase flows with and without phase change in a vertical wavy channel are addressed. The multiphase flow field is resolved using the volume of fluid method (VOF), and the flow equations are discretized and numerically solved by the well-known finite volume method. As a multiphase system without mass transfer, air/water flow is considered. It is shown that numerical simulation is well capable of predicting the various multiphase flow regimes ranging from slug to bubbly flows inside wavy channels. Moreover, accurate predictions of overall pressure drop are provided by numerical solutions for various air and water flow rates and the phase shift angle between wavy channel walls. Additionally, condensing flows of refrigerant R134a are simulated inside wavy channels. It is found that for almost all the cases considered in the present study, the convective heat transfer coefficient is higher in wavy channels in respect to straight channels. However, a significant pressure drop penalty is observed especially for high mass fluxes across wavy channels. Therefore, the use of the wavy channels for the enhancement of condensing heat transfer is only advisable for low mass fluxes with the phase shift angle of 180°. © 2019 Elsevier Ltd

Keywords
Thermal-hydraulic performance, Condensation, Volume of fluid, Wavy channel, Flow regime
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-13846 (URN)10.1016/j.ijheatmasstransfer.2019.04.084 (DOI)000472695300063 ()2-s2.0-85064546226 (Scopus ID)
Available from: 2019-05-24 Created: 2019-05-24 Last updated: 2020-02-03Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-6102-9021

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