THE MECHANISM OF AUGMENTATION HEAT TRANSFER AT HIGH PERFORMANCE BOILING SURFACES

1. (1) ALN溅射表面在R113、R12和N_2三种测试流体中进行了ALN溅射表面池核沸腾实验，并与前人的分析结果进行了比较。此时可以应用的这种多孔层的粒径太小，性能不理想。(2)设计了最佳结构的烧结层青铜颗粒实验表面，对沸腾液体R12和N_2进行了测试。在实验和分析的基础上，对其增强特性进行了讨论。(3)铝等离子体展布表面采用等离子体展布法制备铝颗粒包覆表面。这种粒径为70[m]的多孔表面在沸腾的N_2液体中非常有效。确保一个明确的空隙空间和制备一层大颗粒在技术上是困难的。对多孔层的传热过程进行了分析，并提出了传热关系式，讨论了颗粒直径和烧结层厚度对成核沸腾传热的影响。利用燃尽热通量作为标度因子，提出了一种增强性能模型。

1. Test on basic characteristic at porous surfaces(1) ALN spattered surfaceThe experiment has performed on pool nucleate boiling from ALN spattered sur faces to three test fluids of R113, R12 and N_2, then the results were compared with the analysis proposed earlier [1]. The particle diameter of this porous layer, which can be applied at this moment, is so small that the performance is unsatisfactory.(2) Sintered layer of bronze particleAn experimental surface designed for an optimum structure was tested for boiling liquids R12 and N_2. Discussions of the augmentation characteristics have been made based on the results of experimentation and analysis.(3) Aluminum plasma splayed surfaceAluminum particles coated surface was made with plasma splay method. This porous surface, of particle diameter 70[mum], was highly effective in boiling liquid N_2. Ensuring a well defined void space and preparing a layer of large particles are difficult technically at the process available.2. Analysis of the heat transfer process at the porous layer and proposal of heat transfer correlationThe effects of the particle diameter and the thickness of the sintered layer on nucleate boiling heat transfer are discussed. Making use of the burnout heat flux as a scaling factor, we have proposed a model of augmentation performance.