Flow and Thermal Resistance Network Modeling of Finned Heat Sinks With Bypass Mounted in Rectangular Enclosure

2021 ◽  
Author(s):  
Masaya Fukada ◽  
Takashi Fukue ◽  
Yasuhiro Sugimoto ◽  
Tomoyuki Hatakeyama ◽  
Masaru Ishizuka
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flow Rate ◽  
Heat Sink ◽  
Thermal Design ◽  
Electronic Equipment ◽  
Heat Sinks ◽  
Rate Distribution ◽  
Resistance Network ◽  
Convection Cooling

Abstract This study describes a thermal design method of forced convection cooling in high-density packaging electronic equipment for upstream design processes by flow and thermal resistance network analysis. Forced convection cooling by combining fans and heat sinks is the most standard strategy for dissipating heat from electronic equipment. In recent years, the thermal design of electronic equipment becomes more critical, and fast thermal design is required due to the rapid development of final products. We have been developing the flow and thermal resistance network analysis as the quick thermal design method for electronic equipment. However, an accurate prediction of forced convection cooling performance by finned heat sinks mounted in high-density packaging electronic equipment is generally tricky. Some bypasses, which are clearances between the heat sinks and enclosure walls or other components, exist around the heat sinks. Therefore, a flow rate distribution between the heat sink fins and the bypasses should be predicted. Many researchers have investigated hydrodynamic characteristics and heat transfer characteristics of finned heat sinks. However, many previous studies have been conducted on the finned heat sink performance when there are no bypasses. In order to achieve an optimum design of the finned heat sinks in the upstream configuration regardless of the heat sink dimensions, a systematic database of hydrodynamic characteristics and heat transfer characteristics of the finned heat sinks with bypasses should be investigated. This paper discusses the development of function models of pressure drop, flow rate distribution, and heat transfer of the finned heat sinks with the bypasses for the resistance network analysis through experiments and CFD analysis. Several types of finned heat sinks with 40 mm in width and 80 mm in length were prepared, and these were mounted in a rectangular enclosure with 45 mm in width and height. First, the pressure drop characteristic around the heat sink was investigated. In addition, the flow rate distribution between the heat sink and the bypass was evaluated separately. A flow branching coefficient was developed to predict the flow rate distribution around the heat sink combined with the pressure drop coefficient. Using the developed flow branching coefficient, the flow and thermal resistance network model around the finned heat sink was developed. The results from the proposed resistance network model showed good agreement with those from the experiment.

Compact Modeling of Fluid Flow and Heat Transfer in Straight Fin Heat Sinks

2004 ◽  
Vol 126 (2) ◽  
pp. 247-255 ◽  
Author(s):  
Duckjong Kim ◽  
Sung Jin Kim
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Sink ◽  
Volume Averaging ◽  
Thermal Design ◽  
Heat Sinks ◽  
Compact Modeling ◽  
Flow And Heat Transfer

In the present work, a compact modeling method based on a volume-averaging technique is presented. Its application to an analysis of fluid flow and heat transfer in straight fin heat sinks is then analyzed. In this study, the straight fin heat sink is modeled as a porous medium through which fluid flows. The volume-averaged momentum and energy equations for developing flow in these heat sinks are obtained using the local volume-averaging method. The permeability and the interstitial heat transfer coefficient required to solve these equations are determined analytically from forced convective flow between infinite parallel plates. To validate the compact model proposed in this paper, three aluminum straight fin heat sinks having a base size of 101.43mm×101.43mm are tested with an inlet velocity ranging from 0.5 m/s to 2 m/s. In the experimental investigation, the heat sink is heated uniformly at the bottom. The resulting pressure drop across the heat sink and the temperature distribution at its bottom are then measured and are compared with those obtained through the porous medium approach. Upon comparison, the porous medium approach is shown to accurately predict the pressure drop and heat transfer characteristics of straight fin heat sinks. In addition, evidence indicates that the entrance effect should be considered in the thermal design of heat sinks when Re Dh/L>∼O10.

Forced Convection Air Cooling of Simulated Low Profile Electronic Components: Part 2—Heat Sink Effects

1991 ◽  
Vol 113 (1) ◽  
pp. 27-32 ◽  
Author(s):  
G. L. Lehmann ◽  
J. Pembroke
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Flow Rate ◽  
Heat Sink ◽  
Heat Sinks ◽  
Air Cooling ◽  
Channel Spacing ◽  
Heat Transfer Behavior ◽  
Low Profile ◽  
Transfer Behavior

Forced convection air cooling of an array of low profile, card-mounted components has been investigated. A simulated array is attached to one wall of a low aspect ratio duct. This is the second half of a two-part study. In this second part the presence of a longitudinally finned heat sink is considered. The heat sink is a thermally passive “flow disturbance”. Laboratory measurements of the heat transfer rates downstream of the heat sink are reported and compared with the measured values which occur when no heat sinks are present. Data are presented for three heat sink geometries subject to variations in channel spacing and flow rate. In the flow range considered laminar, transitional and turbulent heat transfer behavior has been observed. The presence of a heat sink appears to “trip” the start of transition at lower Reynolds numbers than when no heat sinks are present. A Reynolds number based on component length provides a good correlation of the heat transfer behavior due to variations in flow rate and channel spacing. Heat transfer is most strongly effected by flow rate and position relative to the heat sink. Depending on the flow regime (laminar or turbulent) both relative enhancement and reductions in the component Nusselt number have been observed. The impact of introducing a heat sink is greatest for flow rates corresponding to transitional behavior.

Thermal Performance of High-Flow Single-Phase Liquid-Cooled Heat Sinks

2012 ◽  
Author(s):  
Ildar F. Akhmadullin ◽  
Randall D. Manteufel ◽  
Christopher Greene
Keyword(s):  
Thermal Resistance ◽  
Flow Rate ◽  
Heat Sink ◽  
Heat Removal ◽  
Internal Flow ◽  
Maximum Flow ◽  
High Flow ◽  
Repeated Measurements ◽  
Heat Sinks ◽  
Flow Rates

Experimental measurements are reported for high-flow liquid-cooled heat sinks designed for cooling electronics components such as a CPU. The flow rate is up to 2 GPM with internal flow passage length scales on the order of 0.1 to 1.0 mm in the primary heat transfer region. Of the designs tested, three achieved maximum flow rates with pressure drops of less than 1.5 psi. Two have lower maximum flow rates because of higher internal flow resistance. In the experiments, particular attention is given to sources of experimental uncertainty and the propagation of uncertainty through the calculations to reported thermal resistance, R (°C/W). Analysis includes bias and precision errors for direct measurement of temperature, flow rate, and pressure drop. Additionally, a separate thermocouple calibration test is reported to establish measurement uncertainties for the system. Main emphasis is made to the error propagation in thermal resistance calculations of each heat sink and measurement of heat removal rate from the CPU. Data is used to determine the standard error for R which ranges up to about 0.05 °C/W with the maximum for one heat sink up to 0.07 °C/W. Averaging of repeated measurements at the same flow rate without accounting for the range of the original data will result in lower uncertainties in the reported results.

Resistance Network Analysis of Airflow and Heat Transfer in a Thin Electronic Equipment Enclosure With a Localized Finned Heat Sink

2010 ◽  
Author(s):  
Takashi Fukue ◽  
Masaru Ishizuka ◽  
Shinji Nakagawa ◽  
Tomoyuki Hatakeyama ◽  
Wataru Nakayama
Keyword(s):  
Network Analysis ◽  
Thermal Performance ◽  
Heat Sink ◽  
Design Method ◽  
Electrical Equipment ◽  
Thermal Design ◽  
Electronic Equipment ◽  
Resistance Network ◽  
Fast Development ◽  
Analytical Accuracy

In recent years, thermal design of electrical equipment becomes importance and fast thermal design is required due to the fast development of electrical devices. We have proposed the flow and thermal resistance network analysis (coupled network analysis) as a fast thermal design method for electrical equipment. In this paper, we described analytical accuracy of the coupled network analysis of thin electronic equipment including the finned heat sink. We especially focused on the prediction of thermal performance on heatsink by using the coupled network analysis. For considering the accuracy of the coupled network analysis, we compared the results of the coupled network analysis with those of CFD analysis and the experiment. The results showed that the coupled network analysis can predict accurate thermal performance of heat sink and moreover accurate temperature distribution of electrical equipment.

scholarly journals Flow Boiling Heat Transfer to a Dielectric Coolant in a Microchannel Heat Sink

2005 ◽  
Author(s):  
Tailian Chen ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Flow Rate ◽  
Heat Sink ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Thermal Design ◽  
Microchannel Heat Sink ◽  
Flow Boiling Heat Transfer

This paper presents an experimental study of flow boiling heat transfer in a microchannel heat sink. The dielectric fluid Fluorinert FC-77 is used as the boiling liquid after it is fully degassed. The experiments were performed at three flow rates ranging from 30 to 50 ml/min. The heat transfer coefficients, as well as the critical heat flux, were found to increase with flow rate. Wall temperature measurements at three locations (near the inlet, near the exit, and in the middle of heat sink) reveal that wall dryout first occurs near the exit of the microchannels. The ratio of heat transfer rate under critical heat flux conditions to the limiting evaporation rate was found to decrease with increasing flow rate, asymptotically approaching unity. Predictions from a number of correlations for nucleate boiling heat transfer in the literature are compared against the experimental results to identify those that provide a good match. The results of this work provide guidelines for the thermal design of microchannel heat sinks in two-phase flow.   This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.

Experiments and Modeling of the Thermal Resistance of In-Line Square Pin-Fin Heat Sinks With Top By-Pass Flow

2003 ◽  
Author(s):  
Mario Urdaneta ◽  
Alfonso Ortega
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Empirical Data ◽  
Heat Sink ◽  
Companion Paper ◽  
Heat Sinks ◽  
One Dimensional ◽  
Pin Fin ◽  
Hydraulic Behavior ◽  
Approach Velocity

The thermal resistance of in-line square-pin fin heat sinks was experimentally investigated. In a companion paper [1], extensive results for the hydraulic behavior of such heat sinks with and without top-bypass were reported. It was shown that the top-bypass, as well as pin pitch, strongly influence the fin flow available for cooling. Systematic measurements of the overall thermal resistance with a uniformly heated base were performed for the same set of twenty aluminum heat sinks. Pin height was varied from 12.5 mm to 22.5 mm, pin pitch was varied from 3.4 mm to 6.33 mm, and base dimensions were kept fixed at 25 × 25 mm. The overall base to ambient thermal resistance was measured as a function of heat sink geometry, approach velocity and by-pass height. Experimental results were compared with predictions based on a simple one-dimensional “two-branch bypass model”. It was found that the overall heat transfer is governed by the fin flow, hence, empirical data for the zero bypass case can be used to predict the decrease of heat sink performance with flow bypass.

Experimental Investigation of Liquid Cooling Through Shallow Copperclad Cavities With Etched Pin-Fin Arrays

2018 ◽  
Author(s):  
Yin Lam ◽  
Nicole Okamoto ◽  
Younes Shabany ◽  
Sang-Joon John Lee
Keyword(s):  
Pressure Drop ◽  
Thermal Resistance ◽  
Surface Area ◽  
Flow Rate ◽  
Heat Sink ◽  
Heat Removal ◽  
Heat Sinks ◽  
Liquid Cooling ◽  
Pin Fin ◽  
Pin Fin Arrays

Heat removal is an increasing engineering challenge for higher-density packaging of circuit components. Microchannel heat sinks with liquid cooling have been investigated to take advantage of high surface-to-volume ratio and higher heat capacity of liquids relative to gases. This study experimentally investigated heat removal by liquid cooling through shallow copperclad cavities with staggered pin-fin arrays. Cavities with pin-fins were fabricated by chemical etching of a copperclad layer (nominally 105 μm thick) on a printed-circuit substrate (FR-4). The overall etched cavity was 30 mm wide, 40 mm long, and 0.1 mm deep. The pins were 1.1 mm in diameter and were distributed in a staggered arrangement. The cavity was sealed with a second copperclad substrate using an elastomer gasket. This assembly was then connected to a syringe pump delivery system. Deionized water was used as the working fluid, with volumetric flow rate up to 1.5 mL/min. The heat sink was subjected to a uniform heat flux of 5 W on the underside. Performance of the heat sink was evaluated in terms of pressure drop and the convection thermal resistance. Pressure drop across the heat sinks was less than 10 kPa, dominated by wall surface area rather than the small surface area contributed by cylindrical pins. At low flow rate, caloric thermal resistance dominated the overall thermal resistance of the heat sink. When compared to a microchannel without pins, the pin-fin microchannel reduced convective thermal resistance of the heat sink by approximately a factor of 4.

Thermal Management of Electronic Equipment: A Review of Technology and Research Topics

1986 ◽  
Vol 39 (12) ◽  
pp. 1847-1868 ◽  
Author(s):  
Wataru Nakayama
Keyword(s):  
Heat Transfer ◽  
Flip Chip ◽  
Nucleate Boiling ◽  
The Body ◽  
Thermal Design ◽  
Electronic Equipment ◽  
Design Criteria ◽  
Research Topics ◽  
Small Component ◽  
Convection Cooling

Increasing miniaturization of microcircuits on chips of increasing size and new schemes of electrical connection, such as flip-chip bonding and surface mounting, are setting more demanding criteria regarding the thermal field within electronic equipment. While the search for a solution to meet a set of prescribed design criteria is becoming more complex, the body of available data needed to perform such a search is quite small. This article describes the two primary functions to be implemented by electronic heat transfer research: the definition of thermal design criteria and the establishment of a thermal packaging database. Examples of actual designs of packages are drawn from recent publications to illustrate the points of technical importance. The examples are packages of DRAM chips, flat-leaded packages of logic chips, and modules with dismountable heat sinks. These examples are used to address thermal stress problems, the problems of fin design, and thermal interface management, respectively. In the section on natural convection cooling, the effects of various factors on the uncertainties pertaining to heat transfer coefficient are assessed in light of the correlations proposed in the current literature. The section on forced convection cooling deals with the problem of heat transfer from an array of packages in a parallel-plate channel. The final section is devoted to the research topics of nucleate boiling heat transfer enhancement, from the surface of a small component, and microchannel cooling.

Thermal Performance of Triangular Folded Fin Heat Sinks in a Duct

2003 ◽  
Author(s):  
Seo Young Kim ◽  
Taeho Ji ◽  
Dong Gyu Choi ◽  
Byung Ha Kang
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flow Velocity ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Performance ◽  
Heat Sink ◽  
Base Plate ◽  
Heat Sinks ◽  
Heat Transfer Characteristics

Experiments have been carried out to investigate the convective heat transfer characteristics from triangular folded fin heat sinks in a suction-type fan duct. The dimension of the triangular folded fin heat sinks is 62 mm in height with a 12 mm thick base plate, 292 mm in width, and 447 mm in length. The inlet flow velocity is varied in the range of 0.6–5.3 m/s. Thermal performance of triangular folded fin heat sinks is evaluated in terms of thermal resistance of heat sinks according to flow velocity and fan power. The results obtained show that the present triangular folded-fin heat sink shows a higher thermal performance compared to a conventional extruded plate-fin heat sink. Especially, a perforated slit folded-fin heat sink displays a lower thermal resistance. As the number of slit fabricated on the perforated folded fins increases, thermal performance is more pronounced.

scholarly journals Theoretical calculation and simulation of surface-modified scalable silicon heat sink for electronics cooling

2021 ◽  
Vol 25 (6 Part A) ◽  
pp. 4181-4187
Author(s):  
Yichi Zhang ◽  
Shinichi Saito ◽  
Yoshishige Tsuchiya ◽  
Yeliang Wang
Keyword(s):  
Thermal Resistance ◽  
Flow Rate ◽  
Heat Sink ◽  
Air Flow ◽  
Electronics Cooling ◽  
Heat Sinks ◽  
Air Flow Rate ◽  
Element Analysis ◽  
Microfabrication Technology ◽  
Surface Modified

A surface-modified scalable heat sink that can be fabricated by applying silicon microfabrication technology has been proposed in this paper. Theoretical estimation of the heat sink thermal resistance is based on the heat sink with overall size of 1 cm ? 1 cm ? 1 cm, and four kinds of structure with various total number of grooves on the surface of fins have been investigated. Finite element analysis has been conducted by using COMSOL Multiphysics where fluid dynamics and heat transfer are taken into account. As a result, the lowest heat sinks thermal resistance of 6.84?C per Watt is achieved for the structure with a larger fin area (13.1 cm2) and a higher inlet air flow rate (4 m/s), suggesting an optimum fin area depending on the air flow rate.

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