斯特林发动机回热器传热和流动特性研究

为优化斯特林发动机回热器的综合性能,采用多孔介质模型对不同孔隙率、丝网材质及不同结构的金属丝网回热器进行了多段式数值模拟研究。基于回热器效率、流阻损失和综合性能参数等指标对模拟结果进行了分析。结果表明:回热器的效率和流动损失随孔隙率的减小而增大;单段式小导热率填料的回热器流动阻力非常大,而采用热端大孔隙率高导热率,冷端小孔隙率低导热率材料的多段式基体结构,能进一步降低回热器流动阻力损失,提高效率,获得更好的回热器性能。

Enhanced Field Emission from Printed Carbon Nanotubes by Hard Hairbrush

A method, the morphology of screen printed carbon nanotube pastes is modified using a hard hairbrush, is presented. In this way, the organic matrix material is preferentially removed. Compared to those untreated films, the turn-on electric field of the treated film decreases from 2.2V/μm to 1.6V/μm, while the total emission current of the treated increases from 0.6mA/cm2 to 3mA/cm2, and uniform emission site density image has also been observed.