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Technical Briefs

Keeping Smartphones Cool With Gallium Phase Change Material

[+] Author and Article Information
Haoshan Ge

Key Laboratory of Cryogenics,
Technical Institute of Physics and Chemistry,
Chinese Academy of Sciences,
Beijing 100190, PRC

Jing Liu

Key Laboratory of Cryogenics,
Technical Institute of Physics and Chemistry,
Chinese Academy of Sciences,
Beijing 100190, PRC;
Department of Biomedical Engineering,
Tsinghua University,
Beijing 100084, PRC
e-mail: jliu@mail.ipc.ac.cn

References cited in the table are [616].

1Correspondence author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received May 18, 2012; final manuscript received December 27, 2012; published online April 11, 2013. Assoc. Editor: W. Q. Tao.

J. Heat Transfer 135(5), 054503 (Apr 11, 2013) (5 pages) Paper No: HT-12-1231; doi: 10.1115/1.4023392 History: Received May 18, 2012; Revised December 27, 2012

With many emerging capabilities in pervasive computing, internet access, wireless communication, and data processing, the smartphone with high central processing unit (CPU) frequency is achieving extremely high running speed which also brings about discomfort to the users due to huge heat released. Here, an automatic temperature regulation strategy using low melting point metal gallium to absorb transitory heat was proposed for the first time. Experiments demonstrate that 3.4125 ml gallium would maintain the module below 45 °C for 16 min at 2.832 W. Such temperature holding time was longer than most of the conventional phase change materials (PCMs). Moreover, some interesting phase change phenomena were also discovered such that mixing SiO2 powder with gallium or just shaking the liquid metal container will help reduce the large supercooling of gallium which is beneficial for the material to quickly recover to its original service state again. The method is expected to be very useful and efficient in maintaining thermal comfort of many handheld electronics, especially for the burgeoning smartphones and panel personal computer (PPC).

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References

Figures

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Fig. 1

(a) is the schematic diagram of the experimental setup and (b) is the isometric view of the container adhered to the mobile electronic device. The temperature of the container was measured with an accuracy ±0.5 °C by the five T-type thermocouples located in the center of outside surface of the container indicated in (b). The sizes of the heater, container and PCM are 26.2 mm × 20.2 mm × 5 mm, 40 mm × 40 mm × 3.5 mm, and 39 mm × 35 mm × 2.5 mm, respectively. The mass of the PCMs, heater and container was 20.167 g for gallium, 5.057 g for sodium sulfate decahydrate, 2.689 g for N-eicosane, 3.105 g for paraffin, 6.2 g for the heater, and 13.4 g for the container, respectively. Depending on the chip set, the heating power ranges from 1 to 3.5 W.

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Fig. 2

Temperature curve with different PCM filled in the container. Throughout the experiment, the ambient temperature was kept around 22 °C. The temperature data were obtained by five T-type thermocouples with locations indicated in Fig. 1(b), and the temperature curve was plotted with the mean value of the data.

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Fig. 3

Temperature curves of mixed PCM and mixed gallium and SiO2 subject to 3 W heating and subsequent natural cooling. Throughout the experiments, the ambient temperature was kept around 20 °C. The temperature data were obtained by five T-type thermocouples with locations indicated in Fig. 1(b), and the temperature curve was plotted with the mean value of the data.

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Fig. 4

Temperature holding time for the gallium PCM under different heating powers. The heating power was calculated with 1.0 V × 1.06 A for 1 W, 1.2 V × 1.32 A for 1.5 W, 1.4 V × 1.49 A for 2 W, 1.5 V × 1.64 A for 2.5 W, 1.7 V × 1.76 A for 3 W and 1.8 V × 1.96 A for 3.5 W. Throughout the experiment, the ambient temperature was kept around 20 °C.

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