Thermally Conductive (TC) Plastics in LED Lamps

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001514-001539
Author(s):  
Rob Janssen ◽  
Ir. L. Douven ◽  
H. K. van Dijk
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Complex Case ◽  
Ideal Case ◽  
General Validity ◽  
Trade Off ◽  
Thermally Conductive ◽  
The Ideal

In section 1, an assessment is made of the typical thermal conductivities attainable in a TC-plastic followed by an examination of the trade-off between increased thermal conductivity and decreased toughness caused by increasing filler load of such a TC-plastic. Having established that currently there is a ceiling conductivity of around 25 W/mK for TC-plastics, i.e., well below the 100 W/mK TC level of metals, subsequently a basic analysis is provided on the suitability of materials with such moderate TC-levels in metal replacement. For this purpose, the ideal case of a unidirectional (1D) heat flow is considered in section 2, in section 3, a more complex case of a bidirectional heat flow is analyzed. Finally, section 4 considers the thermal performance of TC-plastics in a real 3D part, i.e., the heat sink housing of an LED lamp. More specifically, a comparison is made between the thermal performance of the housing molded in a heat conductive plastic and that of an all-aluminum housing. This comparison clearly demonstrates general validity and practical value of the conclusions drawn in sections 2 and 3 and highlights the outstanding suitability of TC-plastics for heat sinks in lighting applications. High performances STANYL TC in particular.

scholarly journals Enhancement of the Thermal Performance of the Paraffin-Based Microcapsules Intended for Textile Applications

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1120
Author(s):  
Virginija Skurkyte-Papieviene ◽  
Ausra Abraitiene ◽  
Audrone Sankauskaite ◽  
Vitalija Rubeziene ◽  
Julija Baltusnikaite-Guzaitiene
Keyword(s):  
Thermal Conductivity ◽  
Thermal Performance ◽  
Comparative Method ◽  
Multiwall Carbon Nanotubes ◽  
Acrylic Resin ◽  
Positive Influence ◽  
Outer Shell ◽  
Ir Camera ◽  
Spacer Fabric ◽  
Thermally Conductive

Phase changing materials (PCMs) microcapsules MPCM32D, consisting of a polymeric melamine-formaldehyde (MF) resin shell surrounding a paraffin core (melting point: 30–32 °C), have been modified by introducing thermally conductive additives on their outer shell surface. As additives, multiwall carbon nanotubes (MWCNTs) and poly (3,4-ethylenedioxyoxythiophene) poly (styrene sulphonate) (PEDOT: PSS) were used in different parts by weight (1 wt.%, 5 wt.%, and 10 wt.%). The main aim of this modification—to enhance the thermal performance of the microencapsulated PCMs intended for textile applications. The morphologic analysis of the newly formed coating of MWCNTs or PEDOT: PSS microcapsules shell was observed by SEM. The heat storage and release capacity were evaluated by changing microcapsules MPCM32D shell modification. In order to evaluate the influence of the modified MF outer shell on the thermal properties of paraffin PCM, a thermal conductivity coefficient (λ) of these unmodified and shell-modified microcapsules was also measured by the comparative method. Based on the identified optimal parameters of the thermal performance of the tested PCM microcapsules, a 3D warp-knitted spacer fabric from PET was treated with a composition containing 5 wt.% MWCNTs or 5 wt.% PEDOT: PSS shell-modified microcapsules MPCM32D and acrylic resin binder. To assess the dynamic thermal behaviour of the treated fabric samples, an IR heating source and IR camera were used. The fabric with 5 wt.% MWCNTs or 5 wt.% PEDOT: PSS in shell-modified paraffin microcapsules MPCM32D revealed much faster heating and significantly slower cooling compared to the fabric treated with the unmodified ones. The thermal conductivity of the investigated fabric samples with modified microcapsules MPCM32D has been improved in comparison to the fabric samples with unmodified ones. That confirms the positive influence of using thermally conductive enhancing additives for the heat transfer rate within the textile sample containing these modified paraffin PCM microcapsules.

scholarly journals Determination of the anisotropic thermal conductivity of an aerogel-based plaster using transient plane source method

2021 ◽  
Vol 2069 (1) ◽  
pp. 012030
Author(s):  
A N Karim ◽  
B Adl-Zarrabi ◽  
P Johansson ◽  
A Sasic Kalagasidis
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Thermal Performance ◽  
Plane Source ◽  
Weak Anisotropy ◽  
Source Method ◽  
Transient Plane Source ◽  
Anisotropic Thermal Conductivity ◽  
Transient Plane Source Method ◽  
Thermal Conductivities

Abstract Aerogel-based plasters are composite materials with declared thermal conductivities in the range of traditional insulating materials, i.e. 30-50 mW/(m·K). Based on the results from reported field measurements, aerogel-based plasters can significantly reduce the thermal transmittance of uninsulated walls. However, the in-situ measured thermal conductivities have sometimes been higher than the declared values measured in laboratory and in the main direction of the heat flow. Meanwhile, the anisotropic thermal performance of aerogel-based plasters, i.e., deviating thermal performance in the different directions of heat flow, has not been explored yet. The objective of this study is thus to evaluate the anisotropic thermal conductivity of an aerogel-based plaster. This is done in a set of laboratory measurements using the transient plane source method. Six identical and cubic samples with the dimensions of 10×10×10 cm3 were paired two and two, creating three identical sample sets. In total, 360 measurements of thermal conductivity and thermal diffusivity, and 130 measurements for specific heat capacity were conducted. The results indicate a weak anisotropy of less than ±6.5 % between the three directions (x, y, z). Considering the accuracy of the selected measurement technique, better than ±5 %, supplementary measurements using another technique are recommended.

Thermally Conductive Plastics for Enhanced Thermal Management

2015 ◽  
Vol 2015 (1) ◽  
pp. 000530-000535
Author(s):  
Chandrashekar Raman
Keyword(s):  
Thermal Conductivity ◽  
Natural Convection ◽  
Thermal Management ◽  
Electronic Devices ◽  
Heat Sinks ◽  
Significant Challenge ◽  
Design Engineers ◽  
Thermally Conductive ◽  
New Material ◽  
Conductive Plastics

Electronic devices continue to shrink while continuing to offer increasing functionality. This trend poses a significant challenge to design engineers who need to adequately address the increasing thermal management requirements of these devices on a shrinking footprint. Thermally conductive plastics have been gaining attention as an innovative new material option to address this challenge. While plastics are typically poor conductors of heat, it is possible to increase the thermal conductivity with the use of certain additives. Unique ceramic additives like boron nitride offer the added advantage of enabling thermally conductive plastic formulations that are also electrically insulating. The replacement of aluminum heat sinks in free (natural) convection environments with thermally conductive plastics is discussed in this paper. The results show it may indeed be possible to replace aluminum with thermally conductive plastic heat sinks in convection limited environments, and if judicious redesign of the plastic heat sink is incorporated, an improved thermal management solution can be realized. Additionally, the benefits of enhancing existing plastic housings to enable an improved thermal management solution are discussed. The results also show that modest enhancements to the thermal conductivity of existing plastic housings can yield significant improvements to the overall thermal management solution as well.

scholarly journals Experimental analysis of effect of base with different inner geometries filled nano PCM for the thermal performance of the plate fin heat sink

2021 ◽  
pp. 243-243
Author(s):  
Periyannan Lakshmanan ◽  
Saravanan Periyasamy ◽  
Mohan Raman
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Phase Shift ◽  
Experimental Research ◽  
Thermal Performance ◽  
Heat Sink ◽  
Electronic Devices ◽  
Base Plate ◽  
Heat Sinks

Experimental research demonstrates the performance of electronic devices on plate fin heat sinks in order to guarantee that operating temperatures are kept as low as possible for reliability. Paraffin wax (PCM) is a substance that is used to store energy and the aluminum plate fin cavity base is chosen as a Thermal Conductivity Enhancer (TCEs). The effects of PCM material (Phase shift material), cavity form base (Rectangular, Triangular, Concave and Convex) with PCM, Reynolds number (Re= 4000-20000) on heat transfer effectiveness of plate fin heat sinks were experimentally explored in this research. The thermal performance of concave base plate fin heat sink with PCM is increased up to 7.8% compared to other cavity base heat sinks.

Buckling of Magnetically Formed Filler Fiber Columns Under Compression Increases Thermal Resistance of Soft Polymer Composites

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Matthew Ralphs ◽  
Chandler Scheitlin ◽  
Robert Y. Wang ◽  
Konrad Rykaczewski
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Volume Fraction ◽  
Potential Method ◽  
Nickel Particles ◽  
Thermal Management Of Electronics ◽  
Thermally Conductive ◽  
Soft Polymer ◽  
Magnetically Aligned

Thermally conductive soft composites are in high demand, and aligning the fill material is a potential method of enhancing their thermal performance. In particular, magnetic alignment of nickel particles has previously been demonstrated as an easy and effective way to improve directional thermal conductivity of such composites. However, the effect of compression on the thermal performance of these materials has not yet been investigated. This work investigates the thermal performance of magnetically aligned nickel fibers in a soft polymer matrix under compression. The fibers orient themselves in the direction of the applied magnetic field and align into columns, resulting in a 3× increase in directional thermal conductivity over unaligned composites at a volume fraction of 0.15. Nevertheless, these aligned fiber columns buckle under strain resulting in an increase in the composite thermal resistance. These results highlight potential pitfalls of magnetic filler alignment when designing soft composites for applications where strain is expected such as thermal management of electronics.

Thermal and EMI Performance of Composite Plastic Molded Heat Sinks and Hybrid TIM Materials

2014 ◽  
Vol 2014 (1) ◽  
pp. 000222-000228 ◽  
Author(s):  
Alpesh Bhobe ◽  
Herman Chu ◽  
Lynn Comiskey ◽  
Xiangyang Jiao ◽  
Xiao Li
Keyword(s):  
Thermal Management ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Thermal Impedance ◽  
Frequency Range ◽  
Reverberation Chamber ◽  
Plastic Materials ◽  
Thermally Conductive ◽  
Electro Magnetic

Heat sinks are widely used in thermal management of electronics. However, it is also well established that a heat sink can couple and radiate electro-magnetic (EM) energy from the same component that it is cooling. As the frequency of these devices continues to increase, it is more crucial to try to suppress the EM radiation at the source. The component suppliers for thermal management and EMI products have been developing materials that are thermally conductive and also have EM absorbing properties. The thermal and EMI material properties of the additives can change the properties of the final material and they may not always be complementary between thermal and EM absorbing behaviors. In this paper, two such hybrid solutions are investigated to understand the thermal and EM absorbing characteristics and interactions. These are: (1) heat sinks made of composite plastic materials; and (2) hybrid RF/thermal interface materials (HRTIMs). For the heat sink study, three heat sinks of the same physical design (40mm square x 8.25mm tall) but with different materials are tested and analyzed. Two of the heat sinks are molded from two different composite plastics (Materials A and B), while the third one is constructed from aluminum and used as the baseline heat sink for comparison. The results presented in Figure 7 show EMI improvement for composite material heat sinks over the traditional aluminum heat sink. Material A provides a broadband reduction of 2–3 dB power whereas Material B heat sink provides significant reduction at lower frequency range of 1–8 GHz. The thermal performance results are plotted in Figure 11 – Figure 14, and the results show that the composite plastic materials are more suitable for applications that have lower power and power density. For the HRTIMs, two different base materials at different thicknesses are investigated and the material details are given in Table 2 . Similar to the heat sink EMI study, Total Radiated Power (TRP) measurements are performed for the HRTIMs in an Electromagnetic Reverberation Chamber in the frequency range of 5–40 GHz show improvement for material TIM 1. The EMI results are plotted in Figure 9 and Figure 10. For thermal performance characterizations, an ASTM D-5470 compliance test stand (Figure 6) is used. The thermal impedance results of these materials are plotted in Figure 15.

Criteria and Methods for Reliable Three-Dimensional Image Reconstruction

1974 ◽  
Vol 32 ◽  
pp. 330-331
Author(s):  
R. A. Crowther
Keyword(s):  
Image Reconstruction ◽  
Finite Number ◽  
Density Distribution ◽  
Electron Micrographs ◽  
Mathematical Problem ◽  
Three Dimensional ◽  
Ideal Case ◽  
Dimensional Image ◽  
General Object ◽  
The Ideal

The reconstruction of a three-dimensional image of a specimen from a set of electron micrographs reduces, under certain assumptions about the imaging process in the microscope, to the mathematical problem of reconstructing a density distribution from a set of its plane projections.In the absence of noise we can formulate a purely geometrical criterion, which, for a general object, fixes the resolution attainable from a given finite number of views in terms of the size of the object. For simplicity we take the ideal case of projections collected by a series of m equally spaced tilts about a single axis.

The DQE of an electron image recording system

1978 ◽  
Vol 36 (1) ◽  
pp. 100-101
Author(s):  
K.-H. Herrmann ◽  
D. Krahl ◽  
H.-P Rust
Keyword(s):  
Primary Electron ◽  
Ideal Case ◽  
Image Recording ◽  
Main Requirement ◽  
High Detection ◽  
Electron Image ◽  
Video Amplifier ◽  
Detection Quantum Efficiency ◽  
Selection Of ◽  
The Ideal

The high detection quantum efficiency (DQE) is the main requirement for an imagerecording system used in electron microscopy of radiation-sensitive specimens. An electronic TV system of the type shown in Fig. 1 fulfills these conditions and can be used for either analog or digital image storage and processing [1], Several sources of noise may reduce the DQE, and therefore a careful selection of various elements is imperative.The noise of target and of video amplifier can be neglected when the converter stages produce sufficient target electrons per incident primary electron. The required gain depends on the type of the tube and also on the type of the signal processing chosen. For EBS tubes, for example, it exceeds 10. The ideal case, in which all impinging electrons create uniform charge peaks at the target, is not obtainable for several reasons, and these will be discussed as they relate to a system with a scintillator, fiber-optic and photo-cathode combination as the first stage.

AN INSTRUMENT FOR MEASURING HEAT FLOW, TEMPERATURE, AND THERMAL CONDUCTIVITY IN THE LUNAR SURFACE LAYER

1970 ◽  
Author(s):  
A. E. Wechsler ◽  
E. M. Drake ◽  
F. E. Ruccia ◽  
J. E. McCullough ◽  
P. Felsenthal ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Surface Layer ◽  
Heat Flow ◽  
Lunar Surface ◽  
Flow Temperature

THE GREEN ROOF THERMAL PERFORMANCE EVALUATION IN COMPARISON TO ASBESTOS CEMENT TILES APPLIED TO LIGHT STEEL FRAME BRAZILIAN BUILDINGS

2018 ◽  
Vol 12 (3) ◽  
pp. 288
Author(s):  
Angélica Felicidade Guião Marcato Costa ◽  
João Alexandre Paschoalin Filho ◽  
Tatiana Tucunduva Philipi Cortese ◽  
Brenda Chaves Coelho Leite
Keyword(s):  
Performance Evaluation ◽  
Relative Humidity ◽  
Heat Flow ◽  
Thermal Performance ◽  
Green Roof ◽  
Steel Frame ◽  
Internal Temperature ◽  
Green Cover ◽  
Asbestos Cement ◽  
Data Representative

This research aimed at comparing the thermal performance provided in experimental modules, one of which was performed with conventional cover, made of asbestos cement tiles; an another with green cover. The structure of the studied modules was executed using Light Steel Frame technique. As an experimental research, modules were built in a wide place, without the interference of shading. Instruments were installed in the inner part of the modules to measure the following data: air temperature, relative humidity. From the collected data, representative episodes have been chosen for the studies that aimed to compare the comfort provided by both modules, built with different roofs. As result, it was verified that the module with green roof had better performance than the module covered with asbestos cement tile in all selected episodes. The module covered with green roof maintained lower internal temperature variation throughout the days, indicating that the green roof has characteristic thermal insulation, reducing the heat flow from the roof.

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