Heat Dissipation Simulation Research of LED Downlight and Optimization of Light Source Layout

In order to solve the heat dissipation problem of LED (light-emitting diode) downlight, CFD thermal simulation software was used to establish LED downlight dissipation model. Materials thermal conductivity, thermal resistance, thermal emissive values, heat load forms and other factors were all taken in considered, and then numerical simulation combined with laboratory measurement methods was used to analysis the lamps dissipation. Based on this method, focused on the dissipation effect with different LED quantities and LED ring distances, and then optimized light source layout of current LED downlight products. After experimental verification, LED working temperatures were more ideal after the light source layout optimized, and it can improve the LED lamp lifetime effectively, this result also has important practice significance in the future LED downlight design process.

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Numerical Analysis for Thermal Performance of High Power Multi-Chip LED Packaging

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.139-141.1433 ◽

2010 ◽

Vol 139-141 ◽

pp. 1433-1437

Author(s):

Kai Lin Pan ◽

Jiao Pin Wang ◽

Jing Liu ◽

Guo Tao Ren

Keyword(s):

High Power ◽

Heat Sink ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Three Dimensional ◽

Junction Temperature ◽

Light Emitting ◽

Die Attach ◽

Dissipation Model ◽

Key Issues

Heat dissipation and cost are the key issues for light-emitting diode (LED) packaging. In this paper, based on the thermal resistance network model of LED packaging, three-dimensional heat dissipation model of high power multi-chip LED packaging is developed and analyzed with the application of finite element method. Temperature distributions of the current multi-chip LED packaging model are investigated systematically under the different materials of the chip substrate, die attach, and/or different structures of the heat sink and fin. The results show that the junction temperature can be decreased effectively by increasing the height of the heat sink, the width of the fin, and the thermal conductivity of the chip substrate and die attach materials. The lower cost and higher reliability for LED source can be obtained through reasonable selection of materials and structure parameters of the LED lighting system.

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The Design of Freeform Surface Fresnel Lens Used for LED Uniform Illumination

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.571-572.976 ◽

2014 ◽

Vol 571-572 ◽

pp. 976-979 ◽

Cited By ~ 1

Author(s):

Yi Dan Dai ◽

En Shi Qu ◽

Li Yong Ren ◽

Xin Chao Du ◽

Hai Juan Ju

Keyword(s):

Heat Dissipation ◽

Light Emitting Diode ◽

Fresnel Lens ◽

Simulation Software ◽

Light Distribution ◽

Freeform Surface ◽

Optical Simulation ◽

Uniform Illumination ◽

Light Emitting ◽

Ray Tracing Simulation

This paper presents a new kind of light emitting diode(LED) secondary light distribution lens which adopts the type of Fresnel lens surface. The research purpose of this paper is to improve the LED heat dissipation efficiency of the secondary light distribution lens and the light efficiency, so as to prolong the service life of the LED. In this paper, we use the numerical method for solving the partial differential equation to establish a freeform surface lens which could produce uniform illumination, then the innovative method of combine the Fresnel lens structure with freeform surface lens was proposed. The design of freeform surface Fresnel lens allows dramatically cut the thickness of the lens (as well as the weight and volume) , it can solve the problem of difficulty in heat dissipation. By comparing the ray tracing simulation results of original freeform surface lens and freeform surface Fresnel lens in optical simulation software, experiments show that the latter not only shows the same degree of illumination uniformity, but also greatly reduced the thickness of the lens.

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Thermal Conductivity and Mechanical Properties of Low-Density Silicone Rubber Filled With Al2O3 and Graphene Nanoplatelets

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4036797 ◽

2017 ◽

Vol 10 (1) ◽

Cited By ~ 14

Author(s):

Yingchun Zhang ◽

Wei Yu ◽

Liye Zhang ◽

Junshan Yin ◽

Jingkang Wang ◽

...

Keyword(s):

Thermal Conductivity ◽

Silicone Rubber ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Thermal Contact ◽

Graphene Nanoplatelets ◽

Rubber Matrix ◽

Heat Conducting ◽

Light Emitting ◽

Potential Applications

A simple approach is developed to obtain a multiscale network of heat conducting by filling spherical alumina (S-Al2O3) and graphene nanoplatelets (GnPs) into silicone rubber (SR). This unique structure effectively minimizes the thermal contact resistance between fillers and matrix. The physical properties of the composites are characterized by thermal conductivity, density, and tensile strength. A high thermal conductivity of 3.37 Wm−1 K−1 has been achieved, which is 47.1% higher than the single filler at the same loading. A strong and obvious synergistic effect has been observed as S-Al2O3 and GnPs filled into silicone rubber matrix. It is interesting that the composites with GnPs have the lower density (2.62 g/cm3, reduced by 6%) and the superior tensile performance, compared to silicone rubber composite with neat S-Al2O3. The composites have the potential applications in heat dissipation of light-emitting diode.

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Simulation Research on the Heat Dissipation Performance of a High Power LED Radiator

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.224.389 ◽

2012 ◽

Vol 224 ◽

pp. 389-394

Author(s):

Shu Zhen Jiang ◽

Zhong Ning Guo ◽

Yu Deng

Keyword(s):

Thermal Analysis ◽

Life Span ◽

High Power ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Environment Friendly ◽

Simulation Research ◽

Light Emitting ◽

High Power Led ◽

Long Life

Applied in illumination area, high power LED (Light Emitting Diode) has a series of advantages with energy saving, environment-friendly, long life span, etc. However, the heat dissipation of the LED is a bottleneck in its development, and has become a key point which must be studied and solved urgently. In this paper, a typical LED lamp is modeled and thermal analysis has been performed using the software of Ansys.

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Comparison of the effects of operating microscopes with light emitting diode and halogen light source on the eye: a rabbit study

Cutaneous and Ocular Toxicology ◽

10.1080/15569527.2021.1949337 ◽

2021 ◽

pp. 1-7

Author(s):

Bahri Aydın ◽

Armagan Ozgur ◽

Huseyin Baran Ozdemir ◽

Pınar Uyar Gocun ◽

Mehmet Arda Inan ◽

...

Keyword(s):

Light Source ◽

Light Emitting Diode ◽

Light Emitting ◽

Halogen Light ◽

Halogen Light Source

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Analysis on High-Power Seaport LED Luminaire with Uniform Light Distribution Based on Optimized Lens and Heatsink

Applied Sciences ◽

10.3390/app11094035 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4035

Author(s):

Jinsheon Kim ◽

Jeungmo Kang ◽

Woojin Jang

Keyword(s):

Light Source ◽

High Power ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Light Distribution ◽

Light Sources ◽

Led Light ◽

High Power Led ◽

Distribution Requirement ◽

Lighting Application

In the case of light-emitting diode (LED) seaport luminaires, they should be designed in consideration of glare, average illuminance, and overall uniformity. Although it is possible to implement light distribution through auxiliary devices such as reflectors, it means increasing the weight and size of the luminaire, which reduces the feasibility. Considering the special environment of seaport luminaires, which are installed at a height of 30 m or more, it is necessary to reduce the weight of the device, facilitate replacement, and secure a light source with a long life. In this paper, an optimized lens design was investigated to provide uniform light distribution to meet the requirement in the seaport lighting application. Four types of lens were designed and fabricated to verify the uniform light distribution requirement for the seaport lighting application. Using numerical analysis, we optimized the lens that provides the required minimum overall uniformity for the seaport lighting application. A theoretical analysis for the heatsink structure and shape were conducted to reduce the heat from the high-power LED light sources up to 250 W. As a result of these analyses on the heat dissipation characteristics of the high-power LED light source used in the LED seaport luminaire, the heatsink with hexagonal-shape fins shows the best heat dissipation effect. Finally, a prototype LED seaport luminaire with an optimized lens and heat sink was fabricated and tested in a real seaport environment. The light distribution characteristics of this prototype LED seaport luminaire were compared with a commercial high-pressure sodium luminaire and metal halide luminaire.

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Influences of Spectral Power Distribution on Circadian Energy, Visual Comfort and Work Performance

Sustainability ◽

10.3390/su13094852 ◽

2021 ◽

Vol 13 (9) ◽

pp. 4852

Author(s):

Jack Ngarambe ◽

Inhan Kim ◽

Geun Young Yun

Keyword(s):

Light Source ◽

Power Distribution ◽

Work Performance ◽

Spectral Power ◽

Light Emitting Diode ◽

Essential Element ◽

Visual Comfort ◽

Light Emitting ◽

Organic Light Emitting Diode ◽

Spectral Power Distribution

Spectral power distribution (SPD) is an essential element that has considerable implications on circadian energy and the perception of lit environments. The present study assessed the potential influences of SPD on energy consumption (i.e., considering circadian energy), visual comfort, work performance and mood. Two lighting conditions based on light-emitting diode (LED) and organic light-emitting diode (OLED) were used as proxies for SPDs of different spectral content: dominant peak wavelength of 455 nm (LED) and 618 nm (OLED). Using measured photometric values, the circadian light (CL), melatonin suppression (MS), and circadian efficacy (CE) of the two lighting sources were estimated via a circadian-phototransduction model and compared. Additionally, twenty-six participants were asked to evaluate the said lit environments subjectively in terms of visual comfort and self-reported work performance. Regarding circadian lighting and the associated energy implications, the LED light source induced higher biological actions with relatively less energy than the OLED light source. For visual comfort, OLED lighting-based conditions were preferred to LED lighting-based conditions, while the opposite was true when considering work performance and mood. The current study adds to the on-going debate regarding human-centric lighting, particularly considering the role of SPD in energy-efficient and circadian lighting practices.

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Optimal Color Lighting for Scanning Images of Flat Panel Display using Simplex Search

Journal of Imaging ◽

10.3390/jimaging4110133 ◽

2018 ◽

Vol 4 (11) ◽

pp. 133

Author(s):

HyungTae Kim ◽

EungJoo Ha ◽

KyungChan Jin ◽

ByungWook Kim

Keyword(s):

Image Quality ◽

Light Source ◽

Light Emitting Diode ◽

Optical Filters ◽

Flat Panel Display ◽

Flat Panel ◽

Light Emitting ◽

Simplex Search ◽

Inspection Systems ◽

Color Control

A system for inspecting flat panel displays (FPDs) acquires scanning images using multiline charge-coupled device (CCD) cameras and industrial machine vision. Optical filters are currently installed in front of these inspection systems to obtain high-quality images. However, the combination of optical filters required is determined manually and by using empirical methods; this is referred to as passive color control. In this study, active color control is proposed for inspecting FPDs. This inspection scheme requires the scanning of images, which is achieved using a mixed color light source and a mixing algorithm. The light source utilizes high-power light emitting diodes (LEDs) of multiple colors and a communication port to dim their level. Mixed light illuminates an active-matrix organic light-emitting diode (AMOLED) panel after passing through a beam expander and after being shaped into a line beam. The image quality is then evaluated using the Tenenbaum gradient after intensity calibration of the scanning images. The dimming levels are determined using the simplex search method which maximizes the image quality. The color of the light was varied after every scan of an AMOLED panel, and the variation was iterated until the image quality approached a local maximization. The number of scans performed was less than 225, while the number of dimming level combinations was 20484. The proposed method can reduce manual tasks in setting-up inspection machines, and hence is useful for the inspection machines in FPD processes.

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Reliability of High-Power Light Emitting Diode Attached With Different Thermal Interface Materials

Journal of Electronic Packaging ◽

10.1115/1.4002299 ◽

2010 ◽

Vol 132 (3) ◽

Cited By ~ 23

Author(s):

Xin Li ◽

Xu Chen ◽

Guo-Quan Lu

Keyword(s):

High Power ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Temperature Cycling ◽

Fluorescent Light ◽

Light Sources ◽

Light Emitting ◽

Die Attach ◽

Nanosilver Paste ◽

Interconnection Material

As a solid electroluminescent source, white light emitting diode (LED) has entered a practical stage and become an alternative to replace incandescent and fluorescent light sources. However, due to the increasing integration and miniaturization of LED chips, heat flux inside the chip is also increasing, which puts the packaging into the position to meet higher requirements of heat dissipation. In this study, a new interconnection material—nanosilver paste is used for the LED chip packaging to pursue a better optical performance, since high thermal conductivity of this material can help improve the efficiency of heat dissipation for the LED chip. The bonding ability of this new die-attach material is evaluated by their bonding strength. Moreover, high-power LED modules connected with nanosilver paste, Sn3Ag0.5Cu solder, and silver epoxy are aged under hygrothermal aging and temperature cycling tests. The performances of these LED modules are tested at different aging time. The results show that LED modules sintered with nanosilver paste have the best performance and stability.

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