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Highly efficient electrocaloric cooling with electrostatic actuation

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Science  15 Sep 2017:
Vol. 357, Issue 6356, pp. 1130-1134
DOI: 10.1126/science.aan5980
  • Fig. 1 A solid-state EC cooling device.

    (A) Schematic illustration of the EC polymer stack and solid-state cooling device (not to scale). NW, nanowire; PMMA, poly(methyl methacrylate). (B) Photograph of a freestanding two-layer P(VDF-TrFE-CFE) stack with CNT electrodes (60-μm thickness and 2 cm by 5 cm of active area): CNT–P(VDF-TrFE-CFE)–CNT–P(VDF-TrFE-CFE)–CNT. (C) Infrared thermal images of P(VDF-TrFE-CFE) film after application (top) and removal (bottom) of a 58.3-MV/m electric field. (D) Photograph of the side view of an EC polymer stack on the heat sink (top) and heat source (bottom) actuated by electrostatic force.

  • Fig. 2 Working mechanism of P(VDF-TrFE-CFE) cooling device to move heat from heat source to heat sink by electrostatic actuation.

    (A) Schematic showing how the electrostatic field drives the actuation of the EC polymer stack toward the heat sink or heat source and the respective position of the EC polymer film during operation of the device. By correlating the electric field of the EC polymer stack with the electrocaloric cycle, heat transfer from the heat source to the heat sink can be achieved. (B) Time domain illustration of the cooling cycle.

  • Fig. 3 Performance of the EC polymer cooling device.

    (A) Power consumption of EC film under an applied electric field of 66.7 MV/m. (B) Comparison of heat flux measured by the heat flux sensor in both heating and cooling modes with an applied electric field of 50 MV/m and frequency of 0.06 Hz. (C) Cyclic testing of heat movement transport from the heat source to the EC polymer stack with an applied electric field of 50 MV/m and frequency of 0.06 Hz. (D) Heat flux as a function of different frequencies of operation. Simulation results, which were obtained by numerically solving the transient heat conduction equation with the finite volume method, agree well with the experimental value. (E) Heat flux of EC polymer film as a function of different applied electric fields at 0.8 Hz. (F) Specific cooling power with corresponding COP is compared with those of magnetocaloric, elastocaloric, and thermoelectric devices reported in the literature.

  • Fig. 4 Performance of the flexible EC cooling device.

    (A) Photograph of a flexible EC device. PDMS, poly(dimethylsiloxane). (B) Temperature change of an overheated smartphone battery with and without an EC cooling device. The inset shows an overheated battery on the top of the EC device.

Supplementary Materials

  • Highly efficient electrocaloric cooling with electrostatic actuation

    Rujun Ma, Ziyang Zhang, Kwing Tong, David Huber, Roy Kornbluh, Yongho Sungtaek Ju, Qibing Pei

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Figs. S1 to S8
    • Table S1
    • References

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