Device‐level thermodynamic model for an electrocaloric cooler

Abstract

An electrocaloric (EC) cooling device model is proposed to study the influence of material properties, operating conditions, and device design on the coefficient of performance (COP). Because the EC temperature change cannot be predicted by ferroelectric material models, a Gaussian-fit model is proposed that achieves accurate predictions for a range of materials. The COP is calculated by considering the heat transfer and work in a thermodynamic cycle that is integrated with the material model. The device model is based on the experiments of Ma et al (Science. 2017;357:1130) and includes contact and convective thermal resistances, the work to apply the electric fields, and dielectric loss heating. A copolymer and a terpolymer are analyzed. The predicted heat flux is in good agreement with the experimental data while the predicted COP is lower. This difference is attributed to an over-prediction of the work because experimental hysteresis loop data are not available. Parametric analysis reveals that: (a) the terpolymer performance is stable over a wide range of operating temperatures, while good performance of the copolymer is limited to near its Curie temperature, and (b) small contact thermal resistances allow for highfrequency operation and a large heat flux. K E Y W O R D Scoefficient of performance, ferroelectric polymer, solid-state cooling, thermal analysis

Enhanced Electrocaloric Response of Vinylidene Fluoride–Based Polymers via One‐Step Molecular Engineering

“…As a consequence of both these changes, the maximum polarization P should increase. Considering that for T > T c , where β is a materials specific constant, [ 30,31 ] Δ S EC is thus expected to be enhanced and, in turn, Δ T EC .…”

“…for T > T c , where β is a materials specific constant, [30,31] ΔS EC is thus expected to be enhanced and, in turn, ΔT EC .…”

Caloric devices: A review on numerical modeling and optimization strategies

“…Plaznik et al, 134 Aprea et al, 135 and Guo et al 104 used the entropy change of Equation (), rather than the polarization. While the majority of the approaches described so far rely on experimental data, Gong et al modeled the EC effect using the Currie–Weiss law along with the Landau–Devonshire theory to obtain the curve 136 . However, only one curve and a constant value were used.…”

“…However, in this case, typical operating frequencies are well above 1 Hz, and the loss mechanisms are no longer negligible. Gong et al have implemented this loss mechanisms using the following loss power source term to the heat equations 136 : where is the vacuum permittivity, ν the frequency, the dielectric loss constant and the root mean square of the electrical field .…”

“…In that respect, most of the fluidic models for MC devices have been validated experimentally, as seen in Table 2. With respect to EC devices, only two models were validated experimentally: the model of Gong et al 136 and that of Plaznik et al 134 Only the model of Sebald et al was validated for the case of eC devices 170 . Figure 12 shows the validation of this eC system model.…”