高温导热油热载体螺纹管传热和压降特性的实验与数值模拟

Experiments and Numerical Simulation of Heat Transfer and Pressure Drop of High Temperature Heat Transfer Fluid in a Ribbed Tube

对高温导热油在螺纹管内流动和传热进行实验研究,结果表明:在层流区,螺纹管沿程阻力系数是相应光管的1.8~3.0倍,Nu数是相应光管的2.8~4.6倍。在湍流区,螺纹管沿程阻力系数是相应光管的3~4倍,Nu数是相应光管的1.8~3.8倍。应用FLUENT对螺纹管和光管进行三维数值模拟,结果表明在螺纹管流场的背流面存在回流区。与光管相比,螺纹管局部协同角的变化范围更大,且在凹槽左右的位置局部协同角接近90°,远离凹槽位置,局部协同角较光管有明显下降。

Experiments and numerical simulation of flow and heat transfer of heat transfer fluid are carried out in a ribbed tube.The distributions of temperature and velocity of heat transfer fluid are predicted by FLUENT software.Both experiments and simulations show that in the laminar flow region the friction coefficient and Nu number of the ribbed tube are 1.8 to 3 times and 2.8 to4.6 times of that in the smooth tube,respectively.However,in the turbulent flow region the results become 3 to 4 times and 1.8 to 3.8 times.Simulated results indicate that there is a recirculation zone exist in the countercurrent surface of the ribbed tube.From simulated temperature and velocity of heat transfer fluid,the local synergy angle is calculated.The variations of local synergy angle is much bigger in the ribbed tube than that in the smooth tube,and approach to 90 degree near the groove.Far from the position of groove,the local synergy angle of ribbed tube decreases obviously comparing to smooth tube.