AMTEC内毛细泵回路流动与换热机理研究

发布时间：2018-09-12 08:13

【摘要】：碱金属热电直接转换器（Alkali Metal Thermal to Electric Converter-AMTEC）是利用β″-Al2O3固体电解质对离子是良导体，对电子绝缘的特性的一种发电装置，具有转换效率高、无运动部件等特点，是一项在太空和地面应用领域里很有前景的技术。AMTEC的功率不仅受到热端温度、冷端温度的影响，还受到毛细泵性能的影响。毛细泵的通流性能直接影响转换器的效率，毛细泵性能的可靠性主要由发生在多孔芯蒸发器的液态钠相变的热力学极限决定，因此研究毛细泵内流体流动与换热机理是很有意义的。本文建立了一个动力学和热力学耦合的二维轴对称数值计算模型，采用相位场方法对气-液界面进行捕捉，通过在方程中添加源项来模拟相变和毛细力。该模型可以较方便求出毛细泵的压力场、速度场、温度场，可以较准确地追踪气-液界面，并能解决了气-液界面处速度和压力的不连续问题。利用该模型模拟和分析了毛细泵的流动特性、换热特性和可靠性等。模拟结果表明，毛细泵流动性能随着平均孔径、孔隙率、温度、导热柱和蒸发器材料热导率的增大而提高，随着电流和输运芯材料热导率的增大而降低；毛细泵的蒸发速率随着蒸发器孔隙率、导热柱和蒸发器材料的热导率的增大而提高，随着输运芯孔隙率和材料热导率的增大而降低；毛细泵的蒸发速率和热效率没有受到平均孔径的影响；毛细泵热效率受蒸发器材料的影响较小，受输运芯材料的影响较明显，随着输运芯材料热导率的的增大而降低；毛细泵临界孔径随着热端温度和电流的增大而降低，随着孔隙率的增大而提高，但受到冷凝器温度的影响很小。
[Abstract]:Alkali metal thermoelectric direct converter (Alkali Metal Thermal to Electric Converter-AMTEC) is a kind of power generating device which uses 尾 "-Al _ 2O _ 3 solid electrolyte as good conductor for ion and good for electronic insulation. It has the characteristics of high conversion efficiency and no moving parts, etc. AMTEC is a promising technology in space and terrestrial applications. The power of AMTEC is affected not only by hot end temperature, cold end temperature, but also by capillary pump performance. The performance of capillary pump directly affects the efficiency of the converter. The reliability of capillary pump is mainly determined by the thermodynamic limit of the liquid sodium phase transition occurring in the porous core evaporator. Therefore, it is meaningful to study the mechanism of fluid flow and heat transfer in capillary pump. In this paper, a two-dimensional axisymmetric numerical model coupled with dynamics and thermodynamics is established. The phase field method is used to capture the gas-liquid interface, and the phase transition and capillary force are simulated by adding a source term to the equation. The model can easily calculate the pressure field, velocity field and temperature field of capillary pump. It can track the gas-liquid interface accurately and solve the problem of velocity and pressure discontinuity at the gas-liquid interface. The model is used to simulate and analyze the flow characteristics, heat transfer characteristics and reliability of capillary pumps. The simulation results show that the flow energy of capillary pump increases with the increase of average pore size, porosity, temperature, thermal conductivity of materials of heat conduction column and evaporator, and decreases with the increase of current and thermal conductivity of core materials. The evaporation rate of capillary pump increases with the increase of the porosity of evaporator, the thermal conductivity of heat conduction column and evaporator, and decreases with the increase of core porosity and thermal conductivity of material. The evaporation rate and thermal efficiency of the capillary pump are not affected by the average aperture, but the thermal efficiency of the capillary pump is less affected by the evaporator material than by the core material, and decreases with the increase of the thermal conductivity of the core material. The critical pore diameter of capillary pump decreases with the increase of hot end temperature and current, and increases with the increase of porosity, but it is little affected by condenser temperature.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH38;TK124

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