Effective Heat Dissipation and Geometric Optimization of an LED Module with AlN Insulation Plate and Modified Fin Heat Sink
- 주제(키워드) Light Emitting Diode (LED) , Thermal resistance , Aluminum nitride (AlN) , Dielectric layer , Response surface methodology , Fin heat sink , Opening , Thermal design optimization , Natural convection
- 발행기관 고려대학교 대학원
- 지도교수 김용찬
- 발행년도 2015
- 학위수여년월 2015. 8
- 학위구분 박사
- 학과 대학원 기계공학과
- 원문페이지 127 p
- 실제URI http://www.dcollection.net/handler/korea/000000060388
- 본문언어 영어
- 제출원본 000045841269
초록/요약
Heat generation increases with higher power input and light output, resulting in a rise in local temperature (viz. a hot spot). Hot spot formation in LEDs tends to decrease their lifespan and reliability. Especially, some of the most important issues are the degradation of light output and luminous efficacy. Therefore, the enhancement of heat dissipation performance by thermal management and design optimization in an LED module and horizontal fin heat sink is necessary to improve the light output, reliability, and lifespan of LEDs. Firstly, a proposed substrate design is suggested to achieve effective heat dissipation in an LED module using an aluminum nitride (AlN) insulation plate instead of the dielectric layer in this study. The heat dissipation performance in a conventional chip on board (COB) LED module is limited by the very low thermal conductivity of the dielectric layer. The geometric configuration of the proposed substrate was optimized by response surface methodology (RSM). The effects of each design parameter were also analyzed in terms of the one-dimensional and spreading thermal resistances. In the proposed substrate design, the junction temperature and total thermal resistance were 24.1% and 55.2% lower, respectively, than the conventional COB module with a copper-based substrate. At a heat input of 15 W, the luminous efficacy of the proposed substrate was about 13.9% higher than that of the conventional COB module. Secondly, this study proposed an enhanced fin heat sink design to improve the cooling performance in the horizontal fin base mounted on an LED module under natural convection. Thermal design and management are very important to LEDs since its performance and reliability are decreased sensitively when the junction temperature increase. The proposed design of the fin heat sink was geometrically optimized using RSM and was investigated by comparing it with conventional fin heat sinks for heat dissipation and luminous performance. The cooling performance of the proposed fin heat sink design was compared with those of the conventional fin heat sink designs. The total thermal resistance of the proposed design decreased by 30.5% against that of the conventional no-opening design at an orientation of 180o and heat input of 10 W. In addition, the luminous efficacy of the proposed design increased by 23.7% against that of the conventional no-opening design at an orientation of 180o and heat input of 25 W. Therefore, the proposed design is more effective in reliability and operating stability compared to conventional fin heat sinks at high power conditions.
more목차
Abstract ii
Contents iv
List of Figures vii
List of Tables x
Nomenclature xi
Chapter 1. Introduction 1
1.1 Background 1
1.2 Literature review 5
1.2.1 Thermal management in an LED module 5
1.2.2 Fin heat sink for LED heat dissipation 10
1.3 Objectives and outline of this study 11
Chapter 2. Numerical Analysis 13
2.1 Thermal simulation for an LED module without fin heat sink 13
2.1.1 LED model 13
2.1.2 Computational model and boundary conditions 15
2.2 Fin heat sink mounted on an LED module 19
2.2.1 Fin heat sink model 19
2.2.2 Computational model and boundary conditions 23
2.2.3 Governing equations 29
2.3 Data reduction 31
2.3.1 LED model without fin heat sink 31
2.3.2 Fin heat sink mounted on an LED module 32
Chapter 3. Model Validation 34
3.1 Thermal measurement in an LED module 34
3.2 Grid dependency test and Comparison with experimental data 38
3.2.1 LED model without fin heat sink 38
3.2.2 Fin heat sink model mounted on an LED module 40
Chapter 4. Effective Heat Dissipation and Geometric Optimization in an LED Module with Aluminum Nitride (AlN) Insulation Plate 42
4.1 Introduction 42
4.2 Optimization on the configuration of the proposed substrate 44
4.3 Effects of the design parameters 49
4.4 Comparison of the enhanced LED module with the conventional LED modules 54
4.5 Estimation of luminous efficacy for the enhanced LED module 60
4.6 Summary 62
Chapter 5. Optimal Thermal Design of a Horizontal Fin Heat Sink with a Proposed Design Mounted on an LED module 63
5.1 Introduction 63
5.2 Optimization on the geometric configuration of the modified fin heat sink 65
5.3 Effects of the geometric design parameters 70
5.4 Comparison between the modified and the conventional fin heat sinks 79
5.5 Estimation of luminous efficacy for the LED module on the modified fin heat sink 95
5.6 Summary 97
Chapter 6. Concluding Remarks 98
6.1 Conclusions 98
6.1.1 Effective heat dissipation and geometric optimization in an LED module 99
6.1.2 Optimal thermal design of a horizontal fin heat sink with a proposed design 100
6.2 Future works 100
References 102
