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An illustration of the operation principle of the electrocaloric cooling cycle investigated in this paper. The cooling cycle consists of 4 steps in which the EC module moves cyclically between the left and right sides of a solid state regenerator coupled with applying/removing electric field. Heat is transported from the left to right of the regenerator, which generates a temperature span across the regenerator.
Top: Schematic of the prototype ECOR studied in this letter, which consists of two 0.25 mm thick 24-layer EC modules and four 0.5 mm thick regenerators. The dimension of the active region of the device is 2 cm × 2.8 cm × 0.25 cm. Bottom: The trapezoid electric field E and movement waveform for the operation of ECOR.
The test result of the ECE induced adiabatic temperature change of the 24-layer EC modules. Due to applying (heating) and removing (cooling) of an 80 MV/m electric field, a ΔTh = 2.25 K heating and ΔTc = 2.15 K cooling were observed around 35 °C. The inset shows the transient EC signal directly recorded.
(a) Testing results on the heating of the prototype ECOR caused by the dielectric loss and friction, respectively: a 0.34 K and 0.53 K temperature increase due to the friction and dielectric loss were observed after 55 s. (b) The transient temperature change measured by the thermocouples at left and right sides of the regenerators when the device was operated at 0.5 Hz under 100 MV/m electric field. A 5 K temperature span was obtained after 80 s operation. Simulation results agree with the experimental data well.
The experimental results of the temperature span, TH–TC, that ECOR can achieve (a) at different applied electric fields at 0.5 Hz. TH–TC = 5 K was obtained when E = 100 MV/m. Simulation results show a 12.9 K temperature span when E increases to 150 MV/m and (b) at 0.5 Hz and 1 Hz under an applied field of 100 MV/m. A 6.6 K temperature span was obtained at 1 Hz. The simulation results indicate that the temperature span can be increased to 12.5 K when the operation frequency is 3 Hz.
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