Thermal management and design optimization for a high power LED work light

This thesis work deals with the optimization project of the heat sink and explains in details the design path of the thermal aspect of a long-life, high quality LED work light, as well as some general fundamentals of product design and manufacturing to consider. Although the path from an idea to the finished product is described mainly from the thermal aspect; the entire process of electronics development and casing mechanical design is not included in this thesis work. The study was done for Five Watts Oy, a company based in Finland designing, developing and manufacturing LED work light solutions for heavy duty equipment. The first prototypes of LED work light were made without proper cooling simulations and thus did not provide sufficient cooling of the LEDs; in a space with no external airflow the prototypes always reached overheat protection temperatures. A proper Computational Fluid Dynamics simulation was made to optimize the most crucial part of the cooling fins, the spacing. The results of the simulation were integrated into overall work light design; nowadays the product is on the market and functioning successfully

Thermal Performance of MR-16 Light Emitting Diode Products

The thermal properties of Light Emitting Diode (LED) products have a significant impact on their longevity and overall performance. Products which are unable to adequately dissipate heat degrade, shortening the projected lifespan. A testing apparatus has been constructed to characterize the thermal behavior of MR-16 LED products. This paper documents the testing setup and measurement results for 9 separate products, and identifies product characteristics which demonstrate higher success at heat dissipation. The thermal performance was quantified using experimental data and heat transfer models. Calculations to quantify the magnitude of heat transferred through radiation and convection in each LED product were performed. Results indicate some of the products are better optimized to enhance convection heat transfer

Design and implementation of an electronic system for a microgravity experiment

The focus of this thesis is to design and develop a complete electronic system consisting of a heating subsystem, an acoustic wave subsystem, and an instrumentation subsystem for an experiment in microgravity. The aim of this work is to ensure the correct performance of all these subsystems in order to demonstrate that convection can be achieved using acoustic waves in microgravity conditions

Design Optimization of a High Power LED Matrix Luminaire

This work presents a methodology for optimizing the layout and geometry of an m x n high power (HP) light emitting diode (LED) luminaire. Two simulators are used to analyze an LED luminaire model. The first simulator uses the finite element method (FEM) to analyze the thermal dissipation, and the second simulator uses the ray tracing method for lighting analysis. The thermal and lighting analysis of the luminaire model is validated with an error of less than 10%. The goal of the optimization process is to find a solution that satisfies both thermal dissipation and light efficiency. The optimization goal is to keep the LED temperature at an acceptable level while still obtaining uniform illumination on a target plane. Even though no optical accessories or active cooling systems are used in the model, the results demonstrate that it is possible to obtain satisfactory results even with a limited number of parameters. The optimization results show that it is possible to design luminaires with 4, 6 and up to 8 HP-LEDs, keeping the LED temperature at about 100 degrees C. However, the best uniformity on a target plane was found by the heuristic algorithm

Design Optimization of a High Power LED Matrix Luminaire

This work presents a methodology for optimizing the layout and geometry of an m x n high power (HP) light emitting diode (LED) luminaire. Two simulators are used to analyze an LED luminaire model. The first simulator uses the finite element method (FEM) to analyze the thermal dissipation, and the second simulator uses the ray tracing method for lighting analysis. The thermal and lighting analysis of the luminaire model is validated with an error of less than 10%. The goal of the optimization process is to find a solution that satisfies both thermal dissipation and light efficiency. The optimization goal is to keep the LED temperature at an acceptable level while still obtaining uniform illumination on a target plane. Even though no optical accessories or active cooling systems are used in the model, the results demonstrate that it is possible to obtain satisfactory results even with a limited number of parameters. The optimization results show that it is possible to design luminaires with 4, 6 and up to 8 HP-LEDs, keeping the LED temperature at about 100 degrees C. However, the best uniformity on a target plane was found by the heuristic algorithm

Development of effective thermal management strategies for LED luminaires

The efficacy, reliability and versatility of the light emitting diode (LED) can outcompete most established light source technologies. However, they are particularly sensitive to high temperatures, which compromises their efficacy and reliability, undermining some of the technology s key benefits. Consequently, effective thermal management is essential to exploit the technology to its full potential. Thermal management is a well-established subject but its application in the relatively new LED lighting industry, with its specific constraints, is currently poorly defined. The question this thesis aims to answer is how can LED thermal management be achieved most effectively? This thesis starts with a review of the current state of the art, relevant thermal management technologies and market trends. This establishes current and future thermal management constraints in a commercial context. Methods to test and evaluate the thermal management performance of a luminaire system follow. The defined test methods, simulation benchmarks and operational constraints provide the foundation to develop effective thermal management strategies. Finally this work explores how the findings can be implemented in the development and comparison of multiple thermal management designs. These are optimised to assess the potential performance enhancement available when applied to a typical commercial system. The outcomes of this research showed that thermal management of LEDs can be expected to remain a key requirement but there are hints it is becoming less critical. The impacts of some common operating environments were studied, but appeared to have no significant effect on the thermal behaviour of a typical system. There are some active thermal management devices that warrant further attention, but passive systems are inherently well suited to LED luminaires and are readily adopted so were selected as the focus of this research. Using the techniques discussed in this thesis the performance of a commercially available component was evaluated. By optimising its geometry, a 5 % decrease in absolute thermal resistance or a 20 % increase in average heat transfer coefficient and 10 % reduction in heatsink mass can potentially be achieved . While greater lifecycle energy consumption savings were offered by minimising heatsink thermal resistance the most effective design was considered to be one optimised for maximum average heat transfer coefficient. Some more radical concepts were also considered. While these demonstrate the feasibility of passively manipulating fluid flow they had a detrimental impact on performance. Further analysis would be needed to conclusively dismiss these concepts but this work indicates there is very little potential in pursuing them further

Improved radial heat sink for led lamp cooling

This paper presents a numerical study concerning an improved heat sink for a light emitting diodes (LED) lamp operating under natural convection conditions. Basic geometry of the heat sink is of cylindrical nature, to be obtained from cutting an aluminum extruded bar comprising a cylindrical central core and a number of uniformly distributed radial fins. Minimum diameter of the central core is fixed and the parameters to be explored are the number of fins, their thickness, length (radial dimension) and height. Although not included in the numerical simulations, the thermal resistance due to the use of a thin thermal interface material (TIM) layer between the LED lamp back and the heat sink is taken into account in the analysis. The main objective of the heat sink is to cool the LED lamp so that the lamp maximum temperature at the contact region with the heat sink is maintained below the critical temperature given by the manufacturer. This is a crucial aspect in what concerns the expected lifetime of the LED lamp and should be achieved at the expenses of as low as possible aluminum mass. Taking these criteria in mind, a design procedure is proposed and followed in the search for the improved heat sink to cool a particular LED lamp. Results obtained with the commercial code ANSYS-CFX clearly show the relative importance of the different governing parameters on the heat sink performance and allow the choice of the better solution within the frame of dimensional constrains. Although the present results concern a particular LED lamp, the proposed methodology can be extended to other types of heat sinks for general light and/or electronic components