The analytical solution is reported for one-dimensional(1D)dynamic conduction heat transfer within a mulilayer system that is the typical structure of electrocaloric devices.Here,the multilayer structure of typical el...The analytical solution is reported for one-dimensional(1D)dynamic conduction heat transfer within a mulilayer system that is the typical structure of electrocaloric devices.Here,the multilayer structure of typical electrocaloric devices is simplified as four layers in which two layers of electrocaloric materials(ECMs)are sandwiched between two semi infinite bodies representing the thermal sink and source.The temperature of electrocaloric layers can be instantaneously changed by extemal electic field to establish the initial temperature profile.The analytical solution includes the temperatures in four bodies as a function of both time and location and heat flux through each of the three interfaces as a function of time.Each of these analytical solutions includes five infinite series.It is proved that each of these series is convergent so that the sum of each series can be calculated using the first N terms of the series.The formula for calculating the value of N is presented so that the simulation of an electrocaloric device,such as the temperature distribution and heat transferred from one body to another can be performed.The value of N is dependent on the thickness of electrocaloric material layers,the time of heat conduction,and thermal properties of the materials used.Based on a case study,it is concluded that the N is mostly less than 20 and barely reaches more than 70.The application of the analytical solutions for the simulation of real electrocaloric devices is discussed.展开更多
Various designs have been introduced to build heat pumps using the electrocaloric effect (ECE). Each of all the curent designs usesat least one moving part, which significantly reduces the reliability of the pump and ...Various designs have been introduced to build heat pumps using the electrocaloric effect (ECE). Each of all the curent designs usesat least one moving part, which significantly reduces the reliability of the pump and adds complexities. In this work, a new all-soliddesign is introduced, in which two layers of an electrocaloric material (ECM) are permanently sandwiched in the source and sink,which would significantly increase the device's reliability since nothing moves and all are permanently bound together. Moreimportantly, the electric fields applied on two ECM layers are independently controlled. A special sequence for the electric fields on .two ECM layers is introduced. Numerical calculation was used to simlulate the device's performance by using the newly introducedanalytical solutions for the heat conduction in the system. It is concluded that a continuous heat transformation from the source tosink at the same temperature can be achieved when the contacting cofficient, K_(ε)=√(k^(c)p^(c)c^(c)_(p))/(k^(o)p^(o)c^(o)_(p)), is very small, where k,ρ, and Cp are thermal conductivity, density, and heat capacity, respectively, while the superscript c and 0 represent the ECM andsource/sink, respectively.展开更多
文摘The analytical solution is reported for one-dimensional(1D)dynamic conduction heat transfer within a mulilayer system that is the typical structure of electrocaloric devices.Here,the multilayer structure of typical electrocaloric devices is simplified as four layers in which two layers of electrocaloric materials(ECMs)are sandwiched between two semi infinite bodies representing the thermal sink and source.The temperature of electrocaloric layers can be instantaneously changed by extemal electic field to establish the initial temperature profile.The analytical solution includes the temperatures in four bodies as a function of both time and location and heat flux through each of the three interfaces as a function of time.Each of these analytical solutions includes five infinite series.It is proved that each of these series is convergent so that the sum of each series can be calculated using the first N terms of the series.The formula for calculating the value of N is presented so that the simulation of an electrocaloric device,such as the temperature distribution and heat transferred from one body to another can be performed.The value of N is dependent on the thickness of electrocaloric material layers,the time of heat conduction,and thermal properties of the materials used.Based on a case study,it is concluded that the N is mostly less than 20 and barely reaches more than 70.The application of the analytical solutions for the simulation of real electrocaloric devices is discussed.
文摘Various designs have been introduced to build heat pumps using the electrocaloric effect (ECE). Each of all the curent designs usesat least one moving part, which significantly reduces the reliability of the pump and adds complexities. In this work, a new all-soliddesign is introduced, in which two layers of an electrocaloric material (ECM) are permanently sandwiched in the source and sink,which would significantly increase the device's reliability since nothing moves and all are permanently bound together. Moreimportantly, the electric fields applied on two ECM layers are independently controlled. A special sequence for the electric fields on .two ECM layers is introduced. Numerical calculation was used to simlulate the device's performance by using the newly introducedanalytical solutions for the heat conduction in the system. It is concluded that a continuous heat transformation from the source tosink at the same temperature can be achieved when the contacting cofficient, K_(ε)=√(k^(c)p^(c)c^(c)_(p))/(k^(o)p^(o)c^(o)_(p)), is very small, where k,ρ, and Cp are thermal conductivity, density, and heat capacity, respectively, while the superscript c and 0 represent the ECM andsource/sink, respectively.
