Constructal Placement of Discrete Heat Sources With Different Lengths in Vertical Ducts Under Natural and Mixed Convection

Abstract

In this study, convective heat transfer in a discretely heated parallel-plate vertical channel which simulates an IC package is investigated experimentally and numerically. Both natural and mixed convection cases are considered. The primary focus of the study is on determining optimum relative lengths of the heat sources in order to reduce the hot spot temperature and to maximize heat transfer from the sources to air. Various values of the length ratio and the modified Grashof number (for the natural convection case)/the Richardson number (for the mixed convection case) are examined. Conductive and radiative heat transfer is included in the analysis while air is used as the working fluid. Surface temperatures of the heat sources and the channel walls are measured in the experimental study. The numerical studies are performed using a commercial CFD code, ANSYS fluent. The variations of surface temperature, hot spot temperature, Nusselt number, and global conductance of the system are obtained for varying values of the working parameters. From the experimental studies, it is showed that the use of identical heat sources reduces the overall cooling performance both in natural and mixed convection. However, relatively decreasing heat sources lengths provides better cooling performance.

Kaldırma Kuvveti ve Yüzey Işınımının Eğik Bir Plakanın Çarpan Jet ile Soğutulmasına Etkilerinin Sayısal Olarak İncelenmesi

“…Havanın ise ışınım açısından katılımcı olmadığı kabul edilmiştir. Bu kabuller doğrultusunda S2S model denklemleri aşağıdaki şekilde ifade edilir [33,34]:…”

Elektronik Bileşenlerin Bir Çift Slot Jet ile Soğutulmasında Nozül Konumunun Soğutma Performansına Etkisi

“…Isı kaynakları aynı zamanda akış bölgesinde birer engel davranışı sergileyerek karmaşık bir akış yapısının oluşmasına sebep olurken, yerel ısı taşınım karakteristikleri üzerinde de önemli etkiler meydana getirmektedir. Literatürde elektronik bileşenleri temsil eden ayrık ısı kaynaklarının çapraz akış kullanılarak doğal, zorlanmış ve karma akış rejimlerinde soğutulmasını esas alan çalışmalar bulunmaktadır [1,8,9]. Aynı zamanda, çarpan jetler kullanılarak ısı transferini iyileştirmeyi amaçlayan ve ısı kaynaklarının çevresindeki karmaşık akış yapısını inceleyen deneysel ve sayısal çalışmalar da mevcuttur.…”

Constructal Design of Elliptical Cylinders with Heat Generating for Entropy Generation Minimization

“…It has also been applied to the designs of cavities and fin heat sinks [ 24 , 61 , 62 , 63 ], channel heat sinks [ 64 , 65 ], heat exchangers [ 66 , 67 , 68 , 69 ], nonuniform heat generating units [ 70 , 71 ], evaporators [ 72 , 73 , 74 ], boiler superheater [ 75 ], tubular arrangements [ 76 , 77 ], dual-pressure turbine [ 78 , 79 ], etc., in recent years. For the constructal design in engineering, heat sources [ 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 ] is one of important and interesting research hotspots.…”

“…Wang et al [ 88 ] carried out the constructal design for several heat source models including discrete stationary and rotating cylinders, singe and discrete elliptical tables. Sarper et al [ 89 ] investigated the constructal design for discrete multi-scale length heat sources in vertical ducts. In addition, Chen et al [ 90 ], Aslan et al [ 91 ] and Armaghani et al [ 92 ] investigated the heat source layout designs.…”

“…From the references mentioned above, although the constructal design and entropy generation minimization have respective theoretical connotations, core positions and optimization purposes, one can see that there are internal physical relations between optimal configuration and entropy generation minimization for various heat and mass transfer processes and systems [ 6 , 9 , 10 , 13 , 14 , 18 , 19 , 22 , 24 , 31 , 34 ], and there is a very interesting research content in thermal design employing the method that combining constructal theory with entropy generation minimization for heat source optimization [ 87 , 88 ]. The heat sources mentioned in [ 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 ] were usually cylinders, square columns, elliptical tables, embedded plate structures, and so on. Based on the above combining method, this paper will establish a 3-D heat dissipation model of discrete elliptical cylinders with heat generating, and design heat generating intensity distribution and thermal conductivity distribution to reach the minimum total DEGR of system.…”