Design And Analysis Of Heat Sinks Kraus Pdf


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Natural convective hybrid fin heat sinks for lightweight and high performance thermal management

However, advances in manufacturing processes and increasing access to simulation tools provide new opportunities to develop superior concepts. Comparing different heat sink design concepts, and consequently identifying the most effective design strategies, is a key requirement of development. However, numerical methods of capturing a comprehensive, but simple assessment of thermal and hydraulic performance, are also required to support product development and promote the realisation of improved performance.

The objective of this article is to establish suitable assessment criteria and apply them to the evaluation of various heatsink concepts for the passive cooling of light emitting diodes LEDs used in general lighting applications.

This was achieved with the aid of a commercially available computational fluid dynamic CFD simulation package. The LED is widely recognised as a revolutionary technology in the lighting sector. Its superior lifetime, energy consumption and quality of light is allowing it to rapidly displace established technologies [4].

However, heat a waste product of their operation compromises their reliability, efficiency and output characteristics [5]. Effective thermal management is consequently a critical aspect of their implementation. Studies from the US DOE [6,7] highlight the significant environmental benefits of LEDs, promoting their use alongside reliable and low energy consumption thermal management devices.

For these reasons passively cooled heatsinks are particularly appropriate and so are the focus of this study. Performance is an ambiguous term which can relate to; thermal conditions, material content, cost, manufacturability, aesthetics and environmental impact amongst many other parameters. For practical purposes it is necessary to restrict its definition to a few simple, but well defined, criteria. First and foremost, the heatsink needs to facilitate sufficient transfer of heat to its environment.

A common measurement of this property is the absolute thermal resistance, defined by the equation:. Absolute thermal resistance captures the combined effects of all heat transfer modes and associated thermal resistances so provides a useful assessment of thermal management capability. In this study thermal resistance was calculated between the peak heatsink temperature i.

Thermal resistance relates to specific load conditions. Models such as those developed by Sadeghi et al. Standardised thermal load definitions such as those proposed by Poppe et al. However, it should be noted that transient thermal testing [10] is an invaluable tool for evaluating and validating thermal resistance characteristics but relies on physical specimen and specialist test equipment.

For simulation it is often most practical to assess the thermal resistance characteristics of each case separately. The same thermal resistance can be established by various heatsink designs, some of which may require less material or exploit superior geometry.

Therefore a secondary measure of how effectively the heatsink design develops its thermal resistance is required. A heatsink employing high thermal conductivity material aluminium in this study , proportionately large surface area and passive cooling is generally described by a small Biot number.

A simple measure of effectiveness E can therefore be estimated as:. Effectiveness has the units m 2. W -1 , with smaller values representing the combination of lowest thermal resistance achieved with the least surface area. Table 1 summarises a series of heatsink design concepts shown in Figure 1 which are considered in this study. The concepts cover a range of conventional and novel forms. The heatsink bounds were restricted to 60 x 65 x 65 mm width, breadth and height.

This was chosen so any subsequent experimental analysis could employ a readily available part. Heatsink height was an arbitrary value in keeping with the base dimensions of the part.

The heatsink base was a 5 mm thick plate leaving an overall fin height of 60 mm. The wall thickness of the fins was approximately 3 mm, although some small variation resulted from the way these models were defined.

The heatsink models were created to allow fin spacing to be modified. Preliminary trials, using CFD analysis, were conducted to identify form which produced the lowest thermal resistance within these bounds. The proposed heatsink models were analysed using a commercially available computer aided engineering software having integrated computer aided design CAD [11] and CFD modules [12]. The computational domain used to model the parallel plate heatsink is shown in Figure 2.

The computational domain was extended to 0. Coordinate origin positioned at centre of heatsink base. Symmetry conditions were applied in xy and zy planes when applicable. The computational domain was based on extents of a controlled experimental test chamber used to benchmark boundary conditions.

The same setup was used to evaluate each heatsink model. The computational mesh is shown in Figure 3 , which is a non-conformal structured Cartesian grid. For a practical compromise between predictive accuracy and processing resources the target computational mesh employed , to , cells per quarter domain.

At least five cells spanned each inter-fin space. The maximum and minimum heatsink temperatures were used as convergence goals. Convergence criteria were determined automatically by the CFD package. The heatsink body was treated as a single homogeneous part. It was oriented with the base horizontal parallel to xz plane. The LED module was included in the simulation model as a separate body attached to the bottom face of the heatsink.

The surfaces of this body were exposed to the surrounding environment so permitted heat transfer from the subject. This was consistent across all models. Thermal interface resistance between the two bodies was defined as 0. W -1 in accordance with data supplied for an appropriate interface augmenting material [13]. Radiative heat transfer was included in the simulation but its role was not optimised.

The heatsink surface was assigned an emissivity of 0. The LED module was assigned an emissivity of 0. Computational analysis is subject to considerable uncertainty [15].

A preliminary benchmark analysis was conducted on a similar case to validate the simulation parameters employed here. The subject shared the same material properties, surface finish, mechanical configuration, operating parameters, heat source and test environment. Absolute accuracy was not critical in this study. The objective was to evaluate the performance of different concepts. A relative estimate is sufficient to guide this process, which these simulation conditions achieve.

The resulting thermal resistance and effectiveness of each heatsink model was calculated and plotted in Figure 4. These results were consistent with expectation. The thermal resistance of the models evaluated here ranged between 3. W -1 diagonal plate and 3. W -1 vertical tube. Effectiveness spanned 0. W -1 staggered pin with open centre and 0.

Some key points to summarise are:. The primary objective of this study was to develop criteria to compare the performance of different heatsinks. The results demonstrated simple, but well defined, methods to achieve this.

They were applied to various heatsink designs and those offering superior performance were revealed. This ability can be used to direct development towards better performing strategies or quantify the impact of any changes. A conventional parallel plate fin heatsink was neither the most effective or offered lowest thermal resistance.

By employing a superior design it was possibly to reduce thermal resistance by 0. W -1 A pin fin heatsink with no pins at its centre was the most effective 0.

W -1 concept while a heatsink employing parallel plate fins in a diagonal arrangement provided the lowest thermal resistance 3. Only thirteen simple heatsink models were analysed in this study. A thorough and definitive comparison of performance would demand more detailed assessment. For more complex models, incorporating multi-objective optimisation, the number of parameters to consider would quickly become impractical. In an effort to manage this a number of constraints were applied.

The Authors wish to acknowledge Tamlite Lighting Ltd. Born in in Stafford, UK. He acquired an MSc degree in mechanical engineering at Staffordshire University in He has since been working in industry and is currently based at Tamlite Lighting UK as Senior Luminaire design engineer.

In he became a chartered engineer with the Institute of Mechanical Engineers. Alongside working in industry he is pursuing a doctoral degree with Loughborough University where he is exploring appropriate thermal management techniques for LED luminaires within a commercial context. Graduated from Loughborough University in and subsequently worked as a research engineer both at Loughborough University and at the Lucas Advanced Engineering Centre in Solihull, Birmingham.

Appointed as a lecturer in and promoted to Senior Lecturer in Born in Sri Lanka, attended St. Obtained Ph. Joined Loughborough University as a lecturer in Electronics Cooling magazine has been providing a technical data column since with the intent of providing you, the readers, with pertinent material properties for use in thermal analyses. We have largely covered the most common materials and their associated thermal properties used in electronics packaging.

Design And Analysis Of Heat Sinks Pdf

Electronics Cooling encompasses thermal design, analysis and experimental characterization of electronic systems as a discrete discipline with the product creation process for an electronics product, or an electronics sub-system within a product e. On-line sources of information are available [1] and a number of books have been published on this topic. Computer cooling is a sub-topic. Heat sinks are devices that are used to extend the surface area of electronic components available for air cooling , helping to lower the components case temperature. Fans are used to increase the air flow.

Heat sink design goals may vary, but in this report, optimization of the vertical heat sink is the main objective. Heat transfer from the heat sink consists of radiation and convection from both the intra-fin passages and the unshielded surfaces of two outer fins. In Cited by: 1. Ritzer and Lau [4] describes the analysis and derivation of an optimum heat sink design for maximizing the thermoelectric cooling performance of a laboratory liquid chiller. Cengel [5] presented the basic principles of heat transfer and. The goal of the analysis is to determine the heat sink geometry and a device setup which allow enough heat dissipation for a given devices and working conditions.

Analysis of microchannel heat exchangers using FEM

Kraus Associates, a consulting firm in Pacific Grove, California. Linear Transformations. Elements of the Linear Transformations. Singular Fins and Spines and Single Elements.

Skip to Main Content. A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. Use of this web site signifies your agreement to the terms and conditions.

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Comparison of Heatsinks used for the Thermal Management of LEDs

The thermal performance of natural convective hybrid fin heat sinks HFHSs are explored numerically and experimentally. Generated CFD models of heat sinks are verified by the measurements and utilized to investigate the effects of fin spacing and internal channel diameter on the thermal performance of the HFHSs at various heat dissipations. The result shows that the increase of the internal channel diameter mitigates the mass-multiplied thermal resistance of the HFHS while it increases the thermal resistance of the HFHS.

Design and analysis of heat sinks

Guest Editors: Y. Muzychka and R. Bar-Cohen, A. June 10, June ; 2 : — The effort described herein extends the use of least-material single rectangular plate-fin analysis to multiple fin arrays, using a composite Nusselt number correlation. The optimally spaced least-material array was also found to be the globally best thermal design.

However, advances in manufacturing processes and increasing access to simulation tools provide new opportunities to develop superior concepts. Comparing different heat sink design concepts, and consequently identifying the most effective design strategies, is a key requirement of development. However, numerical methods of capturing a comprehensive, but simple assessment of thermal and hydraulic performance, are also required to support product development and promote the realisation of improved performance. The objective of this article is to establish suitable assessment criteria and apply them to the evaluation of various heatsink concepts for the passive cooling of light emitting diodes LEDs used in general lighting applications. This was achieved with the aid of a commercially available computational fluid dynamic CFD simulation package.

A finite element method is applied to evaluate the performance of microchannel heat exchangers that are used in electronic packaging. The present approach is validated against the CFD data available in the literature. A comparison of the predicted results with other available results obtained from different concepts shows that the present method is able to predict the surface temperature, the fluid temperature and thus the total thermal resistance of the microchannel heat sink satisfactorily. The method used in the present analysis is an alternative to massive CFD calculations. Quadir, G. Report bugs here. Please share your general feedback.

2 Comments

Nozankeca
11.12.2020 at 08:57 - Reply

Allan D. Kraus, Avram Bar-Cohen Mathematical tools for heat-sink analysis and design Thermal characterization and optimization of plate-fin heatsinks.

Telmo A.
12.12.2020 at 06:33 - Reply

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