Study On Fabrication And Properties Used For Heat Transfer Of Porous Fiber Metals

Thermal transmission is a general phenomenon in our life and a similarity faced by the modern industries. Nowadays, with world economy growing rapidly, the conventional energy is decreasing at the same time. People should pay more attention on the research of energy conservation, while exploiting new energy resources. So that the technology of enhanced heat transfer appears at this time, and become an important subject in the heat-transfer research field. Material is one of most important aspect of enhanced heat transfer. Among all the enhanced heat transfer materials, metal fiber porous materials is one of the best potential heat-transfer materials because of its unique advantages.There are many methods for fabrication metal porous coatings, such as machining, sintering or brazing of particles, electrolytic deposition, flame spraying and ordered wire mesh structures. Heat transfer metal fibre porous materials is one of the important research directions in the field of enhanced heat transfer. But the research on metal fibre porous materials which is prepared by sintered metal fiber has not be extensivly concerned.In this thesis, the heat transfer metal fiber porous materials of stainless steel and copper fiber were prepared by sintering process whose procedure is as follow: fiber→cutting→paving→sintering→trimming→products. The optimal sintering temperatures changed with the fiber diameter. For dissimilar materials, the sintering temperatures were also different. The Scanning Electron Microscopy was show that the materials fabricated present symmetrical interpretation pore structures with randomly stacked fibers and high specific surface. The effects of material type and structure on the behavior of pool boiling heat transfer were experimentally studied. The experiment results showed that the porous materials present excellent heat transfer performance, the heat transfer coefficient of sintered copper fiber materials is about seven times higher than plain surface. The results also showed that : In the condition of atmospheric pressur, the transfer properties of the metal fibre porous materials did not depend on the biber diameter and thickness of the samples.In the range of 80-90%, with the decrease of porositys, the heat transfer increases. When the porosity was 80%, the heat transfer property reached to the maximum.The result of this thesis is valuable for the research and exploitation of highly active heat-change facilities.The research of this dissertation is funded by National "973" Project (project No.2006CB601200)...