内置旋流器紊流传热的研究

The Research on Heat Exchanging of State-Mixer in Tube

对管内置螺旋旋流器不同螺距、不同内件长度情况的换热管进行了实验研究 ,介绍了实验装置 ,阐述了实验现象 ,分析了其强化传热的机理 ,实验结果与理论分析结果吻合。在相同流量的情况下 ,管内侧换热系数与内置旋流器的长度和螺距有一定的关系。减小内件螺距 ,其换热性能相当于增加了裸管的长度。由于流体在管内是以螺旋状前进的 ,其离心力有利于管内温度场不均匀分布冷介质的强化传热 ,并有使温度场均匀化的趋势 ,其作用的大小取决于管内温度场不均匀程度。内件在长度方向上存在有尾流影响区域 ,其影响区域的长短与流速大小有关 ,当流速达到一定值后 ,部分内件的效果与全程内件效果相同。

Experimental research of heat exchange on various of spiral pitch and length of state-mixer in the tube was made. The experimental devices were introduced and phenomena were described. The experiment results are coordinated with the results analyzed by theory. Inside coefficient of heat transfer is influenced by the pitch and length of internal parts under a certain flow. Decreasing the pitch is equivalent to increasing the length of bare tube. The centrifugal force is useful to enhance the heat exchange because of spiral developing of inside fluid. It makes the radius temperature-gradient tend to average. There is a state-mixer tail effective area at the axial direction. Effective length is decided by the rate of fluid. As speed is raised up to certain value,the effect of partial internal parts is equal to that of the full. This is a method for the compact heat exchanger designing.