Numerical Simulation Of Solid-state Electrocaloric Refrigerator With Heat-switch

Global warming and energy consumption promote the refrigeration technology to seek new development.Electrocaloric refrigeration technology has the advantages of environmental friendliness,high refrigeration efficiency and low manufacturing cost,and can realize miniaturization.Therefore,it is of great significance to research electrocaloric refrigeration equipment.Based on the existing electrocaloric refrigeration device,a new solid-state refrigeration device with heat-switch is designed in this paper.The main research contents and results are as follows:?1?Based on the analysis and comparative study of the development history,working principle,characteristics and key technologies of electrocaloric refrigeration technology,a new type of solid-state refrigeration device with thermoelectric material bismuth telluride?Bi₂Te₃?as heat-switch was designed.?2?The numerical simulation of the designed solid-state heat-switch electrocaloric refrigeration device was carried out.The electrocaloric effect is simplified as the internal heat source changing with time,and the heat conduction equations of the electrocaloric module and the thermoelectric module are established respectively.The device were calculated under the operating conditions of 25?as cold end temperature,31?as hot end temperature and 200ms as cycle time.The temperature cloud charts at different times and the temperature changes with time at each detection point were obtained.The cooling capacity reached 227m J and the COP of the device reached 1.84in one cycle.According to the simulation calculation of the two devices with and without electrocaloric module under the same working condition,the cooling capacity of the refrigeration device with electrocaloric module increased by 23%compared with that without electrocaloric module,indicating that the addition of electrocaloric module improved the performance of the device to a certain extent.?3?The influence of temperature span and cycle time of the system on device performance is studied.Calculated the 2 K to 7 K six temperature span under the device performance,the results show that refrigerating capacity and COP of the device is increased with the increase of temperature span is reduced,the thermo dynamical perfectness increased with the increase of temperature span increases after the first decreases,and reach maximum when the temperature span of 6 K,to show that the temperature span of 6 K device of refrigeration cycle is the most close to reverse carnot cycle,the performance of the system is the best.The effect of cycle time on heat absorption and heat release of the device was studied.It was found that the rate of heat absorption and heat release increased rapidly between 50ms and 200ms.After 200ms,the rate of heat absorption and heat release began to decrease significantly and gradually approached saturation.With the extension of the cycle time,COP first increases and then decreases,and reaches the maximum value at 200ms.In addition,the variation of heat absorption and exothermic power with time in different cycle time were studied,and the maximum heat absorption power was obtained at 200ms.The results show that when the cycle time is 200ms,the heat absorption and heat release of the device approach saturation,and the COP of the device also reaches the maximum,indicating that the performance of the system reaches the optimal level when the cycle is 200ms.?4?Compared with the existing similar refrigeration devices,the cooling capacity and cooling power of the new solid-state heat switch electrocaloric refrigeration device designed in this paper have been greatly improved.However,it is still limited by the development of thermoelectric materials and has a certain development space.On the basis of the present electrocaloric refrigeration device and the newly designed solid refrigeration device,two new electrocaloric refrigeration devices are designed by combining the characteristics of gravity heat pipe and pulse pipe.