Thermally Optimum Natural Convection Cooled Longitudinal-Plate Heat Sinks With Horizontal Base Plates

Author(s):  
K. K. Sikka ◽  
C. George

Abstract Longitudinal-plate fin heat sinks are optimized under natural convection conditions for the horizontal orientation of the heat sink base plate. The thermal performance of the heat sinks is numerically modeled. The fin height, thickness and spacing and heat sink width are systematically varied. The numerical results are validated by experimentation. Results show that the thermal resistance of a heat sink minimizes for a certain number of fins on the base plate. The fin spacing-to-length ratio at which the minimum occurs is weakly dependent on the fin height and thickness and heat sink width. The flow fields reveal that the minimum occurs for the heat sink geometry in which the number of fins are maximized such that the flow velocity as the air exits the fins is fully developed. A correlation of the heat transfer with the heat sink geometrical parameters is also developed.

Author(s):  
L. T. Yeh ◽  
Joseph Yeh ◽  
B. T. F. Chung

A CFD (computational fluid dynamics) analysis is performed on the finned heat sinks. For convenience, a commercial CFD code, Flotherm, is utilized in the analysis. Though the code can handle the radiation heat transfer, the present analysis is limited to the natural convection with the base of the heat sink at a constant temperature. The continuous fin configuration is first considered due to the importance of its applications. Several experimental data are available for the vertically straight-fin heat sink and a useful correlation is also developed. For given overall fin dimensions of 15″ × 10.341″ × 2.2″, the correlations are first employed to determine the optimal fin spacing. This optimal fin spacing of 0.439 in is then used to develop the baseline CFD model. The dimensions of the baseline CFD model are as follows: Fin width (in): 10.341. Heat sink length (in): 15. Fin spacing (in): 0.439. Fin height (in): 2.0. Fin thickness (in): 0.1. Fin base plate thickness (in): 0.2. Fin numbers: 20. The baseline model with various fin spacing is analyzed and the results (heat loss from the finned heat sink) compare well with those obtained through the correlations. The analysis is extended to the staggered and in-line fin configurations because of their practical applications. Three different fin lengths, including 1″, 3″ and 5″ fin length for the staggered fin array are examined. The results indicate that the effectiveness of heat transfer is increased as the fin length increasing. The continuous fin configuration is the most efficient, and is followed by the staggered fins and then by the in-line fins.


1994 ◽  
Vol 116 (1) ◽  
pp. 60-67 ◽  
Author(s):  
I. Ahmed ◽  
R. J. Krane ◽  
J. R. Parsons

Flat rectangular plate heat sinks are often used to cool large electronic components by the combined effects of natural convection and thermal radiation. There is, however, a paucity of rational design techniques for these devices. Thus, a systematic program to investigate the use of flat, rectangular plate heat sinks with surface coatings to enhance the net radiative exchange with the surroundings has been undertaken. The preliminary results of this program are presented in this work. A two-dimensional numerical model of a single electronic component mounted on a vertically oriented, flat rectangular plate heat sink that is located immediately above an upward-facing, horizontal component board was developed for this investigation. This model, which is solved using a control volume method based on the SIMPLER algorithm, accounts for the fully-coupled natural convection, conduction and radiative heat transfer processes that occur in the two-dimensional heat sink configuration described above. The results of a parametric study performed with the numerical model confirm the necessity of employing a heat sink, since for the ranges of values investigated, from 64 to 88 percent of the energy dissipated in the component is transferred to the surroundings from the heat sink. The parametric study examines the effects of component power, heat sink size (height), the thickness and emissivity of the heat sink, the vertical location of the component on the heat sink, and the temperature of the horizontal component board on the temperature of the component mounted on the heat sink.


2019 ◽  
Vol 118 (7) ◽  
pp. 44-49
Author(s):  
Rajshekhar V Unni ◽  
Vijay S Majali

In the paper review of studies of heat sinks under natural convection is taken up. The discussions are mainly on experimental works carried out on rectangular fin arrays, optimization of heat sink dimensions and heat transfer enhancement. The geometries of heat sinks, fin spacing, fin height, fin length, fin thickness and fin material and base to ambient temperature difference are the important parameters on which heat transfer rate depends. So the design and optimization of the heat sink geometries becomes essential. It was found that the optimum fin  spacing is ranging from 6.1- 11.9mm which gives maximum heat dissipation; the base to ambient temperature difference is 20-1500C. During most of the experimental work carried out a good thermal conductivity material which is cost-effective was chosen.


Heat sinks are frequently used in the cooling of electrical and electronics devices If the heat sink have very close fin spacing, it increases the surface area but reduces the heat transfer coefficient. On the other hand, if heat sink has wide fin spacing, it reduces the surface area but increases the heat transfer coefficient. Therefore, there is need to optimize the fin spacing that enhanced the heat transfer from the heat sink. A properly selected heat sink may reduced the operating temperature and reduce the risk of failure of components. A steady state natural convective heat transfer from aluminum plate fin heat sink was examined experimentally. The length and thickness of fin was kept constant while height were varied from 5mm to 25mm and spacing varied between 5.5mm to 17mm.After experimentation, it was observed that fin spacing plays important role than any other geometrical parameters. Response surface methodology is used for optimization of fin spacing. It is observed that optimum fin spacing of heat sink is 8.28mm.The error analysis is done with the help of ANN and flow visualization were done using CFD


2015 ◽  
Vol 787 ◽  
pp. 505-509
Author(s):  
A.K. Lakshminarayanan ◽  
M. Suresh

In an era of compact cooling requirements, where air cooling systems seem to be ineffective and consistently, being replaced by liquid cooled systems, with greater watt density heat energy dissipation. Such cooling systems must work with good quality enabling high efficiency. Hence, an attempt is made to fabricate an aluminum alloy based flat plate heat sink with cover and base plate using friction stir welding. The base plate is machined to obtain channels for fluid flow and the cover plate is fitted in the base plate and welded. Two such configurations of these heat sinks were fabricated with varying channel lengths and number of channels. The flow characteristics of the model for these configurations were analyzed numerically using computational fluid dynamics (CFD) software tool, ANSYS fluent 14.


2011 ◽  
Vol 301-303 ◽  
pp. 165-169
Author(s):  
Da Yong Gao ◽  
Jian Xin Zhang ◽  
Ping Juan Niu

The spreading resistance is a very important parameter in the applications of heat sink. The design of electronic devices will fail without considering the influence of the spreading resistance. In this paper, a simple thermal model was simulated by Computational Fluid Dynamics software. Some factors, which have great influence on the spreading resistance, have been analyzed. The spreading resistance decreases significantly with the increasing of the area ratio between the heat source and the base-plate. While the ratio being 1, the spreading resistance reaches the mix value. The greater the thermal conductivity of heat sink, the lower the spreading resistance. With the increasing of the thickness of base-plate, the spreading resistance reduces. However, if the thickness exceeds the critical value, the spreading resistance will increase. And the spreading resistance reaches the mix value while the centers of heat source and the base-plate are overlapped.


Author(s):  
Todd Salamon ◽  
Roger Kempers ◽  
Brian Lynch ◽  
Kevin Terrell ◽  
Elina Simon

Abstract The main drivers contributing to the continued growth of network traffic include video, mobile broadband and machine-to-machine communication (Internet of Things, cloud computing, etc.). Two primary technologies that next-generation (5G) networks are using to increase capacity to meet these future demands are massive MIMO (Multi-Input Multi-Output) antenna arrays and new frequency spectrum. The massive MIMO antenna arrays have significant thermal challenges due to the presence of large arrays of active antenna elements coupled with a reliance on natural convection cooling using vertical plate-finned heat sinks. The geometry of vertical plate-finned heat sinks can be optimized (for example, by choosing the fin pitch and thickness that minimize the thermal resistance of the heat sink to ambient air) and enhanced (for example, by embedding heat pipes within the base to improve heat spreading) to improve convective heat transfer. However, heat transfer performance often suffers as the sensible heat rise of the air flowing through the heat sink can be significant, particularly near the top of the heat sink; this issue can be especially problematic for the relatively large or high-aspect-ratio heat sinks associated with massive MIMO arrays. In this study a vertical plate-finned natural convection heat sink was modified by partitioning the heat sink along its length into distinct sections, where each partitioned section ejects heated air and entrains cooler air. This approach increases overall heat sink effectiveness as the net sensible heat rise of the air in any partitioned section is less than that observed in the unpartitioned heat sink. Experiments were performed using a standard heat sink and equivalent heat sinks partitioned into two and three sections for the cases of ducted and un-ducted natural convection with a uniform heat load applied to the rear of the heat sink. Numerical models were developed which compare well to the experimental results and observed trends. The numerical models also provide additional insight regarding the airflow and thermal performance of the partitioned heat sinks. The combined experimental and numerical results show that for relatively tall natural convection cooled heat sinks, the partitioning approach significantly improves convective heat transfer and overall heat sink effectiveness.


Author(s):  
Sulaman Pashah ◽  
Abul Fazal M. Arif

Heat sinks are used in modern electronic packaging system to enhance and sustain system thermal performance by dissipating heat away from IC components. Pin fins are commonly used in heat sink applications. Conventional metallic pins fins are efficient in low Biot number range whereas high thermal performance can be achieved in high Biot number regions with orthotropic composite pin fins due to their adjustable thermal properties. However, several challenges related to performance as well as manufacturing need to be addressed before they can be successfully implemented in a heat sink design. A heat sink assembly with metallic base plate and polymer composite pin fins is a solution to address manufacturing constraints. During the service life of an electronic packaging, the heat sink assembly is subjected to power cycles. Cyclic thermal stresses will be important at the pin-fin and base-plate interface due to thermal mismatch. The cyclic nature of stresses can lead to fatigue failure that will affect the reliability of the heat sink and electronic packaging. A finite element model of the heat sink is used to investigate the thermal stress cyclic effect on thermo-mechanical reliability performance. The aim is to assess the reliability performance of the epoxy bond at the polymer composite pin fins and metallic base plate interface in a heat-sink assembly.


Sign in / Sign up

Export Citation Format

Share Document