Design And Simulation Of Heat Transfer Structure Of Electrocaloric Materials And Refrigerators

Electrocaloric effect refers to the reversible temperature change of the polar materials when there is an electric field induced polarization change.The refrigeration technology based on electrocaloric effect is advantageous in environmental protection,high efficiency and easy miniaturization.Therefore,it is expected to be widely used in the field of refrigeration in the future.In common electrocaloric materials,organic ferroelectric polymer has great potential in the application of electrocaloric refrigeration due to its strong electrocaloric effect and good flexibility.However,the low thermal conductivity(⁰.2 W m^-1 k^-1)limits the heat transfer process within the polymer,thereby affecting its cooling performance.To solve this problem,this paper proposed the corresponding solutions from the perspective of the thermal conductive structure of the materials and devices:Firstly,the boron nitride nanosheets?BNNs?are characterized by high thermal conductivity and lamellar structure,so this paper proposed to add BNNs into the ferroelectric polymer and accelerated the heat transfer of the polymer through the three-dimensional thermal conductive network formed in the polymer.Experimental results showed that the thermal conductivity of the polymer doped with BNNs was increased by 5times compared with that of the pure polymer.Based on the experimental results,the finite element calculation showed that the heat transfer rate and maximum cooling power density of the polymer were increased by 4 times and 3.5 times respectively with the introduction of BNNs.In order to further improve the heat transfer effect,this paper adopted porous anodic aluminum oxide?AAO?template with high thermal conductivity to assist the heat transfer of the polymer in the hole.The pore size of AAO nanometer could effectively short the heat transfer time of the polymer,and improve the heat transfer rate of the polymer.The simulation results showed that the heat exchange time between the polymer and the substrate was cut by 94 percent with the help of AAO,and the maximum cooling power density was increased by 5 times.Based on the method that porous AAO mentioned above could assist the heat conduction,a new model of electrocaloric refrigerator was designed in this paper.And it accelerated the heat transfer process by inserting a high thermal conducting column of the polymer.Through simulation,the porous structure refrigerator had a maximum improvement of about 4 times in cooling power density and efficiency,compared with the conventional refrigerator.