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    Ferrofluidic open loop pulsating heat pipes: Efficient candidates for thermal management of electronics

    , Article Experimental Heat Transfer ; Vol. 27, issue. 3 , Dec , 2014 , p. 296-312 ; ISSN: 08916152 Mohammadi, M ; Taslimifar, M ; Saidi, M. H ; Shafii, M. B ; Afshin, H ; Hannani, S. K ; Sharif University of Technology
    Thermal management of electronic devices is presently a serious concern. This article investigates the thermal performance of a five-turn open-loop pulsating heat pipe in both start-up and steady thermal conditions. The effects of working fluid, namely water and ferrofluid, heat input, charging ratio, ferrofluid concentration, orientation, as well as application of magnetic field, are explored. Experimental results show that using ferrofluid enhances the thermal performance in comparison with the case of distilled water under certain conditions. In addition, applying a magnetic field on the open-loop pulsating heat pipe charged with ferrofluid improves its thermal performance. Charging... 

    The joint reaction of methanol and i-butane over the HZSM-5 zeolite

    , Article Journal of Industrial and Engineering Chemistry ; Volume 19, Issue 3 , May , 2013 , Pages 915-919 ; 1226086X (ISSN) Roohollahi, G ; Kazemeini, M ; Mohammadrezaee, A ; Golhosseini, R ; Sharif University of Technology
    The effects of i-butane addition to methanol in MTP reaction were investigated over an in-house prepared HZSM-5 catalyst. It was observed that, propylene yield would be enhanced when i-butane fed to the reactor along with methanol. The rising growth of the propylene yield continued to peak on till the balance in thermal condition established. Similar trends have been observed when water was added to the mixture. The effect of WHSV with fixed water composition on product distribution was also studied. The optimum point where the highest amount of propylene yielded was shown to be high depended upon the temperature and residence time  

    Properties of Nafion Under Uniaxial Loading at Different Temperatures: A Molecular Dynamics Study

    , Article Polymer - Plastics Technology and Engineering ; Volume 54, Issue 8 , 2015 , Pages 806-813 ; 03602559 (ISSN) Ozmaian, M ; Naghdabadi, R ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Nafion membrane encounters many different thermal conditions and mechanical loadings because of its wide range of applications as a proton exchange membrane (PEM). Molecular dynamics simulation of hydrated Nafion at different temperatures is carried out to investigate the alteration of the physical properties of Nafion under uniaxial loading over a wide range of temperatures. According to the simulation results, increase of the temperature reduces the yield stress. The results also show that the polymer chains ordering increases the glass transition temperature and enhances the self-diffusion coefficient of water in hydrated Nafion. Comparisons show that the elastic modulus and viscosity... 

    Effect of thermal treatment on fracture behavior of solder joints at various strain rates: Comparison of cyclic and constant temperature

    , Article Engineering Failure Analysis ; Volume 128 , 2021 ; 13506307 (ISSN) Honarvar, S ; Nourani, A ; Karimi, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Fracture tests on Sn93Pb37 solder joints in a double cantilever beam (DCB) configuration were performed at two different strain rates of 10−5 and 0.03 s−1 under mode I loading conditions. In each case, the critical strain energy release rate for crack initiation, Jci, was obtained. Effects of storing specimens at a constant temperature of 75 °C and cyclic temperature varying between 32 and 75 °C were examined at these strain rates. In the strain rate of 0.03 s−1, storing samples in a constant or cyclic temperature caused the fracture energy to decrease significantly with respect to the specimens maintained in ambient temperature. The significant reduction in fracture energy by placing the... 

    Computer modeling of the operating room ventilation performance in connection with surgical site infection

    , Article Scientia Iranica ; Volume 27, Issue 2 , 2020 , Pages 704-714 Sajadi, B ; Saidi, M. H ; Ahmadi, G ; Sharif University of Technology
    Sharif University of Technology  2020
    The primary source of surgical site infection is the deposition of flakes released from the exposed skin of surgical staff or the patient on the exposed surgical wound. In this study, a computational model for simulating air ow and thermal conditions in an operating room is developed, and transport and deposition of particulate contaminants near the wound are analyzed. The results show the formation of a thermal plume over the wound tissue, which is typically at a higher temperature than the surrounding. The thermal plume protects the wound from the deposition of contaminants. In addition, the computational model predicts an optimum value for the inlet air velocity that is mainly maintaining... 

    Novel superabsorbent hydrogel based on natural hybrid backbone: optimized synthesis and its swelling behavior

    , Article Bulletin of the Korean Chemical Society ; Volume 30, Issue 11 , 2009 , Pages 2680-2686 ; 02532964 (ISSN) Pourjavadi, A ; Soleyman, R ; Bardajee Rezanejade, G ; Ghavami, S ; Sharif University of Technology
    The synthesis of a novel superabsorbent hydrogel with natural hybrid backbone via graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (kC, as a polysaccharide) and gelatin (as a protein) under classic thermal conditions is described. The Taguchi method as a strong experimental design tool was used for synthesis optimization. A series of hydrogels were synthesized by proposed conditions of Qualitek-4 Software. Considering the results of 9 trials according to analysis of variance (ANOVA), optimum conditions were proposed. The swelling behavior of optimum hydrogel was measured in various solutions with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in... 

    Numerical simulation of turbulent unsteady compressible pipe flow with heat transfer in the entrance region

    , Article International Conference 'Turbulent Mixing and Beyond', Trieste, 18 August 2007 through 26 August 2007 ; Volume T132 , December , 2008 ; 02811847 (ISSN) Ziaei Rad, M ; Nouri Broujerdi, A ; Sharif University of Technology
    In this paper, the compressible gas flow through a pipe subjected to wall heat flux in unsteady condition in the entrance region is investigated numerically. The coupled conservation equations governing turbulent compressible viscous flow in the developing region of a pipe are solved numerically under different thermal boundary conditions. The numerical procedure is a finite-volume-based finite-element method applied to unstructured grids. The convection terms are discretized by the well-defined Roe method, whereas the diffusion terms are discretized by a Galerkin finite-element formulation. The temporal terms are evaluated based on an explicit fourth-order Runge-Kutta scheme. The effect of...