为了深入考察竖直表面上滴状冷凝强化蒸汽冷凝传热过程的作用机理,设计了滴状冷凝（DWC）、膜状冷凝（FWC）两种冷凝形态的疏水和亲水竖直圆柱形表面,进行了实验研究。结果表明：在30 k Pa压力和相同过冷度的情况下,滴状冷凝传热量是膜...为了深入考察竖直表面上滴状冷凝强化蒸汽冷凝传热过程的作用机理,设计了滴状冷凝（DWC）、膜状冷凝（FWC）两种冷凝形态的疏水和亲水竖直圆柱形表面,进行了实验研究。结果表明：在30 k Pa压力和相同过冷度的情况下,滴状冷凝传热量是膜状冷凝传热量的2~4倍。其主要原因是滴状冷凝时冷凝表面呈疏水性,使经过合并后的大液滴在形成连续的液膜前就从表面上脱落下来,蒸汽能够持续不断地与冷表面直接接触,其换热强度远远大于膜状冷凝。展开更多
In order to study the influence of solid liquid interfacial energy on the filmwise condensation heat transfer performance, a correlation relating heat transfer coefficient with contact angle was derived with respect t...In order to study the influence of solid liquid interfacial energy on the filmwise condensation heat transfer performance, a correlation relating heat transfer coefficient with contact angle was derived with respect to liquid film flow and heat transfer at vapor liquid interface. The calculated results for steam filmwise condensation indicated that heat transfer coefficient increased with increasing contact angle when the contact angle was within a certain range. When contact angle was very small (approaching 0°), the predicted heat transfer coefficient was consistent with the result of classic Nusselt theory.展开更多
基于流体体积函数法(volume of fluid,VOF)建立垂直平行平板通道内膜状冷凝传热预测数值模型,膜状冷凝传热传质过程模拟通过在VOF模型守恒方程中施加基于界面能量平衡方法的源项实现。通过数值分析研究发现,在壁面的顶部,冷凝液膜最薄,...基于流体体积函数法(volume of fluid,VOF)建立垂直平行平板通道内膜状冷凝传热预测数值模型,膜状冷凝传热传质过程模拟通过在VOF模型守恒方程中施加基于界面能量平衡方法的源项实现。通过数值分析研究发现,在壁面的顶部,冷凝液膜最薄,存在层流区域;冷凝液向下流动,一系列不规则的波纹随之出现;影响冷凝传热的主要因素是蒸汽的流速、液膜厚度及流动状态等。展开更多
Six surfaces were prepared with defferent surface division patterns for the experimental investigationof steam condensation heat transfer characteristics for dropwise and filmwise coexisting(DFC)condensationsurfaces u...Six surfaces were prepared with defferent surface division patterns for the experimental investigationof steam condensation heat transfer characteristics for dropwise and filmwise coexisting(DFC)condensationsurfaces under atmospheric pressure Dropwise condensation(DWC)was promoted with an ultrathin polytetrafluoroethylene(PTFE)film,which was prepared by the dynamic ion-beam mixed implantation(DIMI)method.The results showed that the condensation phenomena at the intersection between the dropwise andfilmwise condensation regios were quite different for different relative positions of the dropwise and filmwisecondensation regions.The experimental results revealed that the condensation heat transfer characteristics werehighly influenced by the surface division number and the relative area ratio of the dropwise and filmwise conden-sation regions.The impact of thesc findings on heat transfer enhancement mechanism for condensation heattransfer is discussed in detail.展开更多
文摘为了深入考察竖直表面上滴状冷凝强化蒸汽冷凝传热过程的作用机理,设计了滴状冷凝（DWC）、膜状冷凝（FWC）两种冷凝形态的疏水和亲水竖直圆柱形表面,进行了实验研究。结果表明：在30 k Pa压力和相同过冷度的情况下,滴状冷凝传热量是膜状冷凝传热量的2~4倍。其主要原因是滴状冷凝时冷凝表面呈疏水性,使经过合并后的大液滴在形成连续的液膜前就从表面上脱落下来,蒸汽能够持续不断地与冷表面直接接触,其换热强度远远大于膜状冷凝。
基金国家自然科学基金 (No 5 990 60 0 2 )教育部留学回国人员科研启动基金 (No 1999-747)资助项目~~
文摘In order to study the influence of solid liquid interfacial energy on the filmwise condensation heat transfer performance, a correlation relating heat transfer coefficient with contact angle was derived with respect to liquid film flow and heat transfer at vapor liquid interface. The calculated results for steam filmwise condensation indicated that heat transfer coefficient increased with increasing contact angle when the contact angle was within a certain range. When contact angle was very small (approaching 0°), the predicted heat transfer coefficient was consistent with the result of classic Nusselt theory.
文摘基于流体体积函数法(volume of fluid,VOF)建立垂直平行平板通道内膜状冷凝传热预测数值模型,膜状冷凝传热传质过程模拟通过在VOF模型守恒方程中施加基于界面能量平衡方法的源项实现。通过数值分析研究发现,在壁面的顶部,冷凝液膜最薄,存在层流区域;冷凝液向下流动,一系列不规则的波纹随之出现;影响冷凝传热的主要因素是蒸汽的流速、液膜厚度及流动状态等。
文摘Six surfaces were prepared with defferent surface division patterns for the experimental investigationof steam condensation heat transfer characteristics for dropwise and filmwise coexisting(DFC)condensationsurfaces under atmospheric pressure Dropwise condensation(DWC)was promoted with an ultrathin polytetrafluoroethylene(PTFE)film,which was prepared by the dynamic ion-beam mixed implantation(DIMI)method.The results showed that the condensation phenomena at the intersection between the dropwise andfilmwise condensation regios were quite different for different relative positions of the dropwise and filmwisecondensation regions.The experimental results revealed that the condensation heat transfer characteristics werehighly influenced by the surface division number and the relative area ratio of the dropwise and filmwise conden-sation regions.The impact of thesc findings on heat transfer enhancement mechanism for condensation heattransfer is discussed in detail.
