螺旋丝径对内插螺旋线圈圆管内油类介质强迫对流的影响

The Influence of Wire Diameter on the Forced Convection of Oil in a Tube with Spiral Spring Inserts

实验研究了内插螺旋线圈的水平圆管内30~#透平油的对流强化传热及流阻特性,探索了螺旋丝径的影响。实验圆管为φ10×0.5×900mm的紫铜圆管。其它参数范围为:193.97≤Pr≤464.36;2.7×10~2≤Re≤2.5×10~3;0.333≤t/D≤1.333和3.75≤t/d≤24.实验表明,Re及丝径的增大均使换热系数及阻力增大;Re的增大亦同时造成h/h_及△P/△P_两个比值的增加。Pr的减小可使换热增强,流阻减小,采用(Nu/Nu_)/(f/f_)^(0.29)作为评估传热及流阻综合性能的判据,实验范围内该判据之值介于2.09～3.23之间。此外,综合实验数据得到了传热及流阻两个关系式。

Experimental study of forced convection heat transfer in a horizontal circular tube with spiral spring inserts is performed to investigate the characteristics of fluid flow and heat transfer as well as the influence of the diameter of spring wire. The working fluid is 30# turbine oil and the test tube is made of copper with the dimension of φ10×0. 5× 900 mm. The ranges of experimental variables are 193. 97≤pr≤464. 36 ; 2. 7×102≤Re≤2. 5× 103 ; 6. 333≤t/D≤1. 333 and 3. 75≤t/d≤24. The result shows that the increase of either Re or spring wire diameter causes the increase of heat transfer coefficient and resistance force of fluid flow. The increase of Re also results in the increase of h/ho and ??p/??po- The dectease of Pr due to the increase of fluid temperature leads to the enhancement of heat transfer and the reduction of resistance force. here used to evaluate the combined effect of heat transfer and flow drag. The range of the above ratio is from 2. 09 to 3. 23. Two general correlations tor heat transer and flow drag are obtained according to the experimental data.