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5, Tubes
Finned tube is used in welding technology and equipment for special processing, the heat transfer fluid in the pipe during a single phase forced convective heat transfer. Its main characteristic is to expand through the heat pipe heat transfer area, enhanced heat transfer tube means to improve the heat transfer performance. Within the United States first proposed in 1971, finned tube, and the nineties in the twentieth century, has developed a highly efficient phase change heat transfer enhanced tube inside the spiral fin tube. Japan, the former Soviet Union and other countries a lot of research work. The early eighties, Hitachi Cable Limited research shows that using the wrong type of spiral around the finned tube heat transfer enhancement can single-phase fluid tube heat transfer coefficient increased to 2.8 times as fluorescent tubes [6].
6, Zoom Tube
Zoom Tube is a multi-section alternately tapered section and the diverging section of composition, the fluid in the tube under the effect of the structure caused by turbulence, thereby improving heat transfer efficiency. Scaling applied to single-phase flow tube studies have carried out a lot. South China University of Technology proposed a modified zooming tube section of each scale unit to minimize the expansion section, and using circular convex, concave arc and straight lines connected. But also the improved management of natural convective boiling heat transfer experimental research shows that the improved zoom control of the natural convection boiling heat transfer performance is better than normal zoom control [7]. Chen Ying [8,9] The experiments and simulation, show that the improved zoom control has better heat transfer effect.
7, the three-dimensional fin tube
Within the fin tube is through three-dimensional tool to go through a specific method of processing from the ordinary high-pipe wall heat transfer components. Fluid in the tube by the action of three-dimensional rib to the thickness of the thermal boundary layer thinning, thereby enhancing the convective heat transfer film coefficient. In some flue gas convective heat transfer in the ribbed tube has a unique three-dimensional self-cleaning function, Qing Li Fang [10] The experiment found that smoke inside the ribbed pipe and three-dimensional heat transfer coefficient up to 3.2 times that of fluorescent tubes, than other enhanced tubes, such as good heat transfer pipe thread. 上一頁 [1] [2] |
