A computational study on mixed convection with surface radiation in a channel in presence of discrete heat sources and v
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A computational study on mixed convection with surface radiation in a channel in presence of discrete heat sources and vortex generator based on RSM S. K. Mandal1 · Arnab Deb1 · Dipak Sen1 Received: 30 October 2019 / Accepted: 30 April 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Numerical simulation of mixed convection and surface radiation in a horizontal rectangular channel with five discrete heat sources protruded from the bottom wall has been carried out. Air is considered as working fluid and flow to be laminar, steady, and incompressible. The parameters varied are Reynolds number (Re) = 100–750, the spanwise position of vortex generator (VG) x/H = 1.8, 2.8, 3.8 4.8 and 5.8, the pitchwise position of VG, y/H = 0.5, 0.6 and 0.7 and emissivity of the heat source, εc = 0.1–0.9, while emissivity of the VG and channel walls is fixed as 0.9. The governing equations are solved based on SIMPLE algorithm using ANSYS 16.2. The results show that the Reynolds number, the position of vortex (spanwise and pitchwise), and emissivity of heat source have significant effects on heat transfer. It is also noticed that the maximum nondimensional temperature (θmax) is 47.81% with VG at Re = 250 with change in emissivity of the heat sources from 0.1 to 0.9. Finally, a correlation has been developed for average non-dimensional temperature (θavg) using response surface methodology. Keywords Surface radiation · Mixed convection · Rectangular channel · Vortex generator · RSM List of symbols A Height of the triangular VG (m) B Width of the base of the triangular base (m) cp Specific heat capacity at constant pressure (kJ kg−1 K−1) D Distance between two chips (m) Ek Emissive power of surface k Fkj View factor from kth element to the jth element of an enclosure G Acceleration due to gravity (m s−2) H Height of heat source (m) H Channel width (m) Jj Radiosity of surface j Jk Radiosity of surface k K Thermal conductivity (W m−1 K−1) L Length of the channel (m) P Pressure at a location (N m−2) Patm Atmospheric pressure (N m−2) qv Volumetric heat generation (W m−3) Re Reynolds number * Dipak Sen [email protected] 1
Department of Mechanical Engineering, National Institute of Technology Arunachal Pradesh, Yupia 791112, India
RSM Response surface methodology T Temperature at a location (K) Tatm Atmospheric temperature (K) ΔTref Reference temperature difference, (qv ∗ w ∗ h)∕kf U Velocity in x direction (m s−1) uin Velocity at inlet (m s−1) uout Velocity at outlet (m s−1) V Velocity in y direction (m s−1) VG Vortex generator W Width of heat source (m) X Pitchwise distance of VG (m) Y Spanwise distance of VG (m Greek symbols β Thermal expansion co-efficient (K−1) θ Non-dimensional temperature (T − Tatm)/ΔTref ρ Density of the fluid (kg m−3) µ Dynamic viscosity (N s m−2) ε Surface emissivity Subscript avg Average c Heat source f Fluid m Maximum
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Introduction Electronic devices nowadays are becoming more sophisticated and highly compact. Continued mi
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