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Abstract
Many high-power electronic devices such as high-power light-emitting diodes and aerial devices work intermittently. If some of the heat generated by the chips could be stored in the thermal storage medium during the working time and then be released to the ambient in the nonworking time, the heat dissipation load of the heat sinks could be diminished and a better thermal characteristic could be achieved. Inspired by this idea, we proposed a thermal storage substrate and investigated its thermal storage properties by experiment in this study. First, the composite phase-change material (CPCM) was prepared as the thermal storage medium. Second, the thermal and phase-transition properties of the CPCM were studied through differential scanning calorimeter tests. Third, the thermal conductivity of the CPCM was measured for the analysis of thermal performance. Afterward, the CPCM-based substrate was fabricated and several experiments were conducted to examine its thermal storage performance. The results showed that the thermal storage substrate could store the heat, as much as 55,773.80 J, which accounts for 32% of the heat generated by the heat source approximately. With so much heat stored in the CPCM, the temperature of the heat source went up much more slowly. To accelerate the heat conduction inside the CPCM, five aluminum pillars were added into the substrate. As a result, the temperature of the heat source and the substrate wall decreased by 3.5°C and 4.5°C, respectively.
NOMENCLATURE
| A | = | heat transfer area, m2 |
| c | = | characteristic constants, dimensionless |
| Cp | = | specific thermal, J kg−1 K−1 |
| CPCM | = | composite phase-change material |
| DSC | = | differential scanning calorimeter |
| g | = | acceleration gravity, m s−2 |
| Gr | = | Grashof number, dimensionless |
| H | = | latent heat of phase change material, kJ kg−1 |
| h | = | heat-transfer coefficient, W m−2 K−1 |
| L | = | length of the surfaces, m |
| l | = | characteristic length, m |
| LED | = | light-emitting diode |
| m | = | mass of the materials, kg |
| n | = | characteristic constants, dimensionless |
| Nu | = | local Nusselt number, dimensionless |
| P | = | heat power of the heat source, W |
| PCM | = | phase-change material |
| Pr | = | Prandtl number, dimensionless |
| Q | = | heat, J |
| T | = | temperatures of the materials, K |
| t | = | heating time, s |
| tw | = | characteristic temperature, K |
| T∞ | = | temperatures of the ambient, K |
| ΔT | = | temperature difference, K |
| W | = | width of the substrate, m |
Greek Symbols
| β | = | volume coefficient of expansion, K−1 |
| η | = | experimental error, dimensionless |
| θw | = | temperature difference, K−1 |
| λ | = | thermal conductivity of the PCM, W m−1 K−1 |
| ν | = | kinematic viscosity, m2·s−1 |
| Φ | = | heat flow, W |
Subscripts
| con | = | natural convection |
| gra | = | graphite |
| heat | = | heat source |
| in | = | input heat |
| m | = | melting |
| pra | = | paraffin |
| store | = | storage heat |
| sub | = | substrate |
Superscripts
| exper | = | experimental |
| gra | = | graphite |
| pra | = | paraffin |
| theory | = | theoretical |
Additional information
Notes on contributors
Jinyan Hu
Jinyan Hu received the B.E. degree in energy and power engineering in 2012 from Huazhong University of Science and Technology, Wuhan, China, where he has been working toward the Ph.D. degree in engineering thermophysics. His current research is focused on phase-change materials (PCM) and their application in the thermal management of electronic devices.
Run Hu
Run Hu received the B.E. degree in energy and power engineering in 2010 from Huazhong University of Science and Technology, Wuhan, China, where he has been working toward the Ph.D. degree in engineering thermophysics. His current research interests include optical and thermal analysis of high-power light-emitting diode packaging.
Yongming Zhu
Yongming Zhu has received the B.E. degree in energy and power engineering in 2013 from Huazhong University of Science and Technology, Wuhan, China. His current research interest is thermal management of quantum dots.
Xiaobing Luo
Xiaobing Luo received the Ph.D. degree in 2002 from Tsinghua University, Beijing, China. From 2002 to 2005, he was with Samsung Electronics, Seoul, Korea, as a senior engineer. At the end of 2005, he became an associate professor at Huazhong University of Science and Technology, Wuhan, and in 2007, he became a full professor after exceptional promotion. Since 2011, he has been Associate Dean of the School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan. He is also a professor with the Wuhan National Laboratory for Optoelectronics, Wuhan, China. He has published more than 160 papers. Among these, 82 papers are peer-reviewed international journal papers. He has obtained more than 20 granted patents in the United States and China.