Using Graphene-powder-based Thermal Interface Material for High Lumen LED Array Chip: An Experimental Study of Heat Dissipation

An LED is solid-state lighting with low environmental impact and green technology. It has the advantages of high luminance, long life, structural strength, and short reaction time. With the continuous improvement in luminous efficiency, the heat energy accumulates rapidly, resulting in a chip-on-boa...

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Bibliographic Details
Published in:Sensors and materials 2020-12, Vol.32 (12), p.4277
Main Authors: Hsu, Chih-Neng, Chen, Chun-Chih, Chang, Chen-Hui, Wang, Cheng-Chi
Format: Article
Language:English
Subjects:
Air flow
Arrays
Attenuation
Continuous improvement
Differential pressure
Environmental impact
Flow velocity
Flow visualization
Forced convection
Graphene
Heat conductivity
Heat transfer
Light attenuation
Luminous efficacy
Pitot tubes
Qualitative analysis
Reaction time
Thermal boundary layer
Thermal conductivity
Thermocouples
Visualization
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Summary:An LED is solid-state lighting with low environmental impact and green technology. It has the advantages of high luminance, long life, structural strength, and short reaction time. With the continuous improvement in luminous efficiency, the heat energy accumulates rapidly, resulting in a chip-on-board (COB) array LED contact surface that easily exceeds the specification temperature Tj and exhibits a sharp drop in light attenuation. Therefore, we blended graphene powder materials and silicone oil to develop excellent graphene grease (10, 15, and 20 wt%) as a contact surface interface medium material with high thermal conductivity, enabling the high-brightness COB array LED to maintain a stable and excellent heat transfer performance. The mixing concentration percentage of the thermally conductive grease is an important influential parameter. Forced convection airflow speeds of 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 m/s are used to simulate the coolant flow rate. The qualitative and quantitative experimental verifications, discussion, the analysis of temperature changes, and flow visualization using a thermal imager flow field are carried out. The contact surface interface medium material with 15 wt% graphene grease has a relatively good thermal conductivity, but increasing or decreasing the graphene grease concentration causes no clear improvement in thermal conductivity. From the results of forced convection flow visualization, we observed that the airflow speed increases, the thermal boundary layer gradually becomes thinner, and the heat recirculation zone gradually dissipates, which improves the heat transfer effect. In the process of forced convection experiment, we have used the thermocouple temperature (Tcase, Tf, and Ta) sensor and the rotating frequency sensor of axial fan control airflow speed, and a Pitot tube for differential pressure sensing is used to measure and transmit data to a recorder.
ISSN:0914-4935
DOI:10.18494/SAM.2020.3137