تحلیل عددی تأثیر وجود بافل بر افزایش انتقال حرارت جریان نانوسیال روی یک پله پسرو: رابطه برازش برای عدد ناسلت متوسط

نوع مقاله : مقاله پژوهشی

نویسنده

دانشکده مهندسی مکانیک، دانشگاه گیلان، رشت، ایران

چکیده

در مقاله حاضر، تأثیر حضور بافل بر الگوی جریان و افزایش انتقال حرارت جابجایی اجباری نانوسیال مس با پایه آب در محدوده رژیم آرام روی یک پله پسرو به صورت عددی مورد مطالعه قرارگرفته‌است. برای حل معادلات جریان و دما از روش حجم محدود استفاده شده‌است. در این مطالعه، تأثیر پارامترهای هندسی بافل از قبیل ارتفاع، عرض و تعداد آن، و همچنین عدد رینولدز و کسر حجمی نانوذرات بر الگوی جریان و انتقال حرارت بررسی شده‌است. همچنین به منظور ارزیابی همزمان افزایش انتقال حرارت و افت فشار، شاخص ارزیابی عملکرد تعریف شده‌است. نتایج حاکی از آن است که با افزایش ارتفاع بافل، عدد رینولدز و کاهش کسر حجمی، شاخص ارزیابی عملکرد افزایش می‌یابد. در تمامی شرایط، مقدار افزایش عدد ناسلت متوسط و شاخص ارزیابی عملکرد، برای عرض بافل معادل 2 برابر ارتفاع پله نسبت به سایر مقادیر عرض بافل، به ترتیب حدود %7/6 و %15 می‌باشد. همچنین نتایج نشان می‎دهد که حضور 2 بافل بهتر از تعداد دیگر بافل‌ها است. به منظور جمع‌بندی، یک رابطه برازش برای نسبت عدد ناسلت متوسط همچون تابعی از عدد رینولدز، کسر حجمی نانو ذرات، تعداد بافل، ارتفاع بافل و عرض بافل با خطای متوسط %2/88 ارائه شده‌است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Numerical analysis of the effect of baffle on heat transfer enhancement nanofluid flow over a backward facing step: A correlation for the average Nusselt number

نویسنده [English]

  • Hesam Moayedi
Thermo-Fluids Department, Faculty of Mechanical Engineering, University of Guilan, Iran
چکیده [English]

In this paper, the effect of baffle on the flow field and heat transfer enhancement of forced convection of Cu-water nanofluid flow in the laminar regime over a backward facing step is numerically investigated. Finite volume method is used to solve governing equations of flow and temperature. In this study, the influence of baffle geometrical parameters as height, width and number of baffles, as well as the Reynolds number and the volume fraction of nanoparticles on the flow filed and heat transfer are evaluated. Also, to evaluate the simultaneous of the heat transfer enhancement and pressure drop, the performance evaluation index is calculated. It is obvious that by increasing the Reynolds number and decreasing the volume fraction of nanoparticles, the performance evaluation index is increased. The average Nusselt number and the performance evaluation index for the width of baffle 2 are higher than other cases about 7.6% and 15% respectively. The results show that using 2 baffles must be more beneficial than other number of baffles. Finally, a correlation for the average Nusselt number as a function of Reynolds number, volume fraction of nanoparticles, number of baffles, baffle height and baffle width is presented with an average error of 2.88%.

کلیدواژه‌ها [English]

  • Numerical Analysis
  • Backward facing step
  • Nanofluid
  • baffle
  • heat transfer
[1] B.F. Armaly, F. Durst, J. Pereira, B. Schönung, Experimental and theoretical investigation of backward-facing step flow, Journal of fluid Mechanics, 127 (1983) 473-496.
[2] J.B. Saldana, N. Anand, V. Sarin, Forced convection over a three-dimensional horizontal backward facing step, International Journal for Computational Methods in Engineering Science and Mechanics, 6(4) (2005) 225-234.
[3] S. Acharya, G. Dixit, Q. Hou, Laminar mixed convection in a vertical channel with a backstep: a benchmark study, ASME-PUBLICATIONS-HTD, 258 (1993) 11-11.
[4] M.P. Boruah, P.R. Randive, S. Pati, Hydrothermal performance and entropy generation analysis for mixed convective flows over a backward facing step channel with baffle, International Journal of Heat and Mass Transfer, 125 (2018) 525-542.
[5] M. Moradzadeh, B. Ghasemi, A. Raisi, Nanofluid mixed-convection heat transfer in a ventilated cavity with a baffle, Amirkabir Journal of Mechanical Engineering, 48(3) (2016) 257-266. (in Persian).
[6] J. Nie, Y. Chen, R.F. Boehm, H.-T. Hsieh, Parametric Study of Turbulent Separated Convection Flow Over a Backward-Facing Step in a Duct, in:  ASME/JSME 2007 5th Joint Fluids Engineering Conference, American Society of Mechanical Engineers Digital Collection, 2007, pp. 997-1004.
[7] S. Kumar, S. Vengadesan, The effect of fin oscillation in heat transfer enhancement in separated flow over a backward facing step, International Journal of Heat and Mass Transfer, 128 (2019) 954-963.
[8] X. Shi, P. Jaryani, A. Amiri, A. Rahimi, E.H. Malekshah, Heat transfer and nanofluid flow of free convection in a quarter cylinder channel considering nanoparticle shape effect, Powder Technology, 346 (2019) 160-170.
[9] H. Namadchian, I. Zahmatkesh, S. Alavi, Numerical simulation of nanofluid flow in a annular porous channel with using the Darcy-Brinkman-Forcheimer model and two-phase mixed model, Amirkabir Journal of Mechanical Engineering, (2020). (in Persian).
[10] M. Nazari, S. Maleki-Delarestaghi, A. Shakeri, Experimental Investigation of the Forced Convection Heat Transfer of Nanofluids in Curved Tubes, Amirkabir Journal of Mechanical Engineering, 50(2) (2018) 347-358. (in Persian).
[11] A. Aghaei, H. Khorasanizadeh, G.A. Sheikhzadeh, A numerical study of the effect of the magnetic field on turbulent fluid flow, heat transfer and entropy generation of hybrid nanofluid in a trapezoidal enclosure, The European Physical Journal Plus, 134(6) (2019) 310.
[12] M.S. Pour, S.G. Nassab, Numerical investigation of forced laminar convection flow of nanofluids over a backward facing step under bleeding condition, Journal of Mechanics, 28(2) (2012) N7-N12.
[13] A.J. Chamkha, F. Selimefendigil, Forced convection of pulsating nanofluid flow over a backward facing step with various particle shapes, Energies, 11(11) (2018) 3068.
[14] F. Selimefendigil, H.F. Öztop, Numerical analysis of laminar pulsating flow at a backward facing step with an upper wall mounted adiabatic thin fin, Computers & Fluids, 88 (2013) 93-107.
[15] H.A. Mohammed, F. Fathinia, H.B. Vuthaluru, S. Liu, CFD based investigations on the effects of blockage shapes on transient mixed convective nanofluid flow over a backward facing step, Powder technology, 346 (2019) 441-451.
[16] H. Togun, M.R. Safaei, R. Sadri, S.N. Kazi, A. Badarudin, K. Hooman, E. Sadeghinezhad, Numerical simulation of laminar to turbulent nanofluid flow and heat transfer over a backward-facing step, Applied Mathematics and Computation, 239 (2014) 153-170.
[17] R. Nath, M. Krishnan, Numerical study of double diffusive mixed convection in a backward facing step channel filled with Cu-water nanofluid, International Journal of Mechanical Sciences, 153 (2019) 48-63.
[18] S. Salman, A.A. Talib, S. Saadon, M.H. Sultan, Hybrid nanofluid flow and heat transfer over backward and forward steps: A review, Powder Technology, 363 (2020) 448-472.
[19] H. Mohammed, O.A. Alawi, M. Wahid, Mixed convective nanofluid flow in a channel having backward-facing step with a baffle, Powder Technology, 275 (2015) 329-343.
[20] H. Mohammed, O. Alawi, N.C. Sidik, Mixed convective nanofluids flow in a channel having forward-facing step with baffle, J. Adv. Res. Appl. Mech, 24 (2016) 1-21.
[21] Y. Ma, R. Mohebbi, M.M. Rashidi, Z. Yang, Y. Fang, Baffle and geometry effects on nanofluid forced convection over forward-and backward-facing steps channel by means of lattice Boltzmann method, Physica A: Statistical Mechanics and its Applications,  (2020) 124696.
[22] A. Heshmati, H. Mohammed, A. Darus, Mixed convection heat transfer of nanofluids over backward facing step having a slotted baffle, Applied Mathematics and Computation, 240 (2014) 368-386.
[23] E. Abu-Nada, Application of nanofluids for heat transfer enhancement of separated flows encountered in a backward facing step, International Journal of Heat and Fluid Flow, 29(1) (2008) 242-249.
[24] Y. Malmir-Chegini, N. Amanifard, Heat transfer enhancement inside semi-insulated horizontal pipe by controlling the secondary flow of oil-based ferro-fluid in the presence of non-uniform magnetic field: A general correlation for the Nusselt number, Applied Thermal Engineering, 159 (2019) 113839.
[25] D. Choudhury, A.E. Woolfe, Computation of laminar forced and mixed convection in a heated vertical duct with a step, ASME HEAT TRANSFER DIV PUBL HTD, ASME, NEW YORK, NY,(USA), 1993, 258 (1993) 29-36.
[26] M. El‐Refaee, M. Elsayed, N. Al‐Najem, I. Megahid, Steady‐state solutions of buoyancy‐assisted internal flows using a fast false implicit transient scheme (FITS), International Journal of Numerical Methods for Heat & Fluid Flow, 6(6) (1996) 3-23.
[27] A. Kumar, A.K. Dhiman, Effect of a circular cylinder on separated forced convection at a backward-facing step, International journal of thermal sciences, 52 (2012) 176-185.
[28] J.-T. Lin, B.F. Armaly, T. Chen, Mixed convection in buoyancy-assisting, vertical backward-facing step flows, International Journal of Heat and Mass Transfer, 33(10) (1990) 2121-2132.