Browsing by Subject "Heat flux"

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    Effects of couple stresses on the heat transfer and entropy generation rates for a flow between parallel plates with constant heat flux
    (Elsevier Masson SAS, 2016) Aksoy Y.
    In this study, the flow and heat transfer of a fluid with couple stresses is investigated. The flow caused by the pressure gradient between parallel plates is considered as incompressible, steady and fully developed while the bottom plate is adiabatic and the upper plate is exposed to a constant heat flux. Governing equations, i.e. momentum and energy, are derived and solved analytically. Using the analytical results, effects of couple stresses on the Nusselt number as a heat transfer performance parameter and entropy generation rates in the channel are presented via graphs and tables. In addition, second law analysis is performed by calculating mean entropy generation rates and Bejan number along the channel height. © 2016 Elsevier Masson SAS. All rights reserved.
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    Numerical analysis of heat transfer in a flat-plate solar collector with nanofluids
    (Begell House Inc., 2017) Yurddaş A.; Çerçi Y.
    Heat transfer aspects of a typical flat-plate solar collector utilizing water-based nanofluids as the working fluid were analyzed numerically. Water-based nanofluids of various compositions containing metallic Al2O3 and Cu nanoparticles with volume fractions ranging from 1% to 5% were examined, and the effects of the nanofluids on the heat transfer were quantified. Relevant parameters such as the heat flux, Reynolds number, and the collector tilt angle were calculated and compared to each other at different boundary conditions. The flat-plate solar collector geometry was simplified, and only a fluid carrying pipe with an absorber surface was chosen as a numerical model with a particular at ention to symmetry, instead of taking the entire collector geometry. The numerical model was controlled and confirmed by applying it to similar studies existing in the pertinent literature. All numerical solutions were carried out by using a commercial finite volumes of ware package called ANSYS Fluent. The results show that the nanofluids increase the heat transfer rate ranging from 1% to 8%, when compared to water as a working fluid. © 2017 by Begell House, Inc.
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    Numerical Simulation of the Condensation Flow of the Isobutane (R600a) inside Microchannel
    (Taylor and Francis Ltd., 2021) Basaran A.; Benim A.C.; Yurddas A.
    A numerical investigation of the condensing flow of isobutane inside microchannel has been performed. Impact of mass flux, hydraulic diameter, and vapor quality on the heat transfer rate and pressure drop is determined. To this purpose, steady-state numerical simulations of condensation flow of isobutane have been performed at mass fluxes ranging from 200 to 600 kg/m2s inside a single circular microchannel with varying diameter. Similar to the usual operation conditions, the simulations have been conducted for constant saturation temperature and constant wall heat flux as the thermal boundary condition. The proposed model has been based on the volume of fluid approach, which is an interface tracking method. The Lee model has been used to model the phase change mass transfer at the interface. A verification study has been performed by comparing the proposed model results with the experimental and visual data available in the literature. The currently available correlations are assessed by comparisons with the simulation results. Based on the presently validated simulations, a new correlation has been proposed for the heat transfer coefficient and pressure drop of isobutane condensing flow inside small-scale channels. This is a novel aspect of the present paper, since such a correlation does not yet exist. © 2021 Taylor & Francis Group, LLC.