生成物CO_2能否及时排除流道和甲醇溶液能否更有效的传输到扩散层对液体进料的直接甲醇燃料电池性能有着重要影响.Volume of Fluid(VOF)可以用来研究平行流道孔逸出CO_2气体的演变,包括气泡的生长、变形、脱离及运动规律.通过建立流道...生成物CO_2能否及时排除流道和甲醇溶液能否更有效的传输到扩散层对液体进料的直接甲醇燃料电池性能有着重要影响.Volume of Fluid(VOF)可以用来研究平行流道孔逸出CO_2气体的演变,包括气泡的生长、变形、脱离及运动规律.通过建立流道的三维模型,研究了湿润性对流道中气泡演变的影响.通过软件FLUENT进行模拟,模拟分析了亲水性(35°)、中性(90°)、弱疏水性(115°)、强疏水性(125°)情况的扩散层壁面,结果表明:气泡是由两相流的压力差和表面张力共同作用形成的,弱疏水性的扩散层表面有利于气泡脱离及气泡聚合的过程.弱疏水性的扩散层表面相对于亲水性的壁面,气泡排出的更稳定;弱疏水性的扩散层表面相对于强疏水性壁面,气泡脱离体积更小,脱离的时间更短.展开更多
This paper presents the results of a first successful attempt to produce hollow micro- and nano-particles of a large variety of materials, dimensions, shapes and hollow attributes by using an environmentally friendly ...This paper presents the results of a first successful attempt to produce hollow micro- and nano-particles of a large variety of materials, dimensions, shapes and hollow attributes by using an environmentally friendly and cheap technology, common in polymer processing and known as gas foaming. The central role played by ad hoc polymeric hollow micro- and nano-particles in a variety of emerging applications such as drug delivery, medical imaging, advanced materials, as well as in fundamental studies in nanotechnology highlights the wide relevance of the proposed method. Our key contribution to overcome the physical lower bound in the micro- and nano-scale gas foaming was to embed, prior to foaming, bulk micro- and nano-particles in a removable and deformable barrier film, whose role is to prevent the loss of the blowing agent, which is otherwise too fast to allow bubble formation. Furthermore, the barrier film allows for non-isotropic deformation of the particle and/or of the hollow, affording non-spherical hollow particles. In comparison with available methods to produce hollow micro- and nano-particles, our method is versatile since it offers independent control over the dimensions, material and shape of the particles, and the number, shape and open/closed features of the hollows. We have gas- foamed polystyrene and poly-（lactic-co-glycolic） acid particles 200 ~m to 200 nm in size, spherical, ellipsoidal and discoidal in shape, obtaining open or closed, single or multiple, variable in size hollows.展开更多
文摘生成物CO_2能否及时排除流道和甲醇溶液能否更有效的传输到扩散层对液体进料的直接甲醇燃料电池性能有着重要影响.Volume of Fluid(VOF)可以用来研究平行流道孔逸出CO_2气体的演变,包括气泡的生长、变形、脱离及运动规律.通过建立流道的三维模型,研究了湿润性对流道中气泡演变的影响.通过软件FLUENT进行模拟,模拟分析了亲水性(35°)、中性(90°)、弱疏水性(115°)、强疏水性(125°)情况的扩散层壁面,结果表明:气泡是由两相流的压力差和表面张力共同作用形成的,弱疏水性的扩散层表面有利于气泡脱离及气泡聚合的过程.弱疏水性的扩散层表面相对于亲水性的壁面,气泡排出的更稳定;弱疏水性的扩散层表面相对于强疏水性壁面,气泡脱离体积更小,脱离的时间更短.
文摘This paper presents the results of a first successful attempt to produce hollow micro- and nano-particles of a large variety of materials, dimensions, shapes and hollow attributes by using an environmentally friendly and cheap technology, common in polymer processing and known as gas foaming. The central role played by ad hoc polymeric hollow micro- and nano-particles in a variety of emerging applications such as drug delivery, medical imaging, advanced materials, as well as in fundamental studies in nanotechnology highlights the wide relevance of the proposed method. Our key contribution to overcome the physical lower bound in the micro- and nano-scale gas foaming was to embed, prior to foaming, bulk micro- and nano-particles in a removable and deformable barrier film, whose role is to prevent the loss of the blowing agent, which is otherwise too fast to allow bubble formation. Furthermore, the barrier film allows for non-isotropic deformation of the particle and/or of the hollow, affording non-spherical hollow particles. In comparison with available methods to produce hollow micro- and nano-particles, our method is versatile since it offers independent control over the dimensions, material and shape of the particles, and the number, shape and open/closed features of the hollows. We have gas- foamed polystyrene and poly-（lactic-co-glycolic） acid particles 200 ~m to 200 nm in size, spherical, ellipsoidal and discoidal in shape, obtaining open or closed, single or multiple, variable in size hollows.
