毛细管内液氮的自然对流换热数值计算分析

Numerical study of the natural convection heat transfer of liquid nitrogen in the capillary tubes

主要探讨了毛细管管径以及倾角对其内的加热丝与液氮的换热效果的影响。应用FLUENT软件对0、30、60、90倾角下管径为1.2mm和2.0mm的毛细管内的加热丝与液氮的换热情况进行了三维数值模拟,得到了管内液氮的速度、温度以及加热丝的温度分布情况。数值计算结果与实验结果吻合的比较好。计算结果表明倾角为30°和60°的换热效果最好,大管径下的换热情况要比小管径的换热效果好。

Natural convection in liquid nitrogen around a thin wire heater placed in the center of the capillary is numerically studied. We mainly discuss the effect of the diameter sizes and the inclination angles of the capillary tubes on the heat transfer performance. The inclination angles of the capillary tubes are 0 ,30 ,60 and 90 with the diameters of 1.2mm and 2.0mm. The numerical simulations are performed with the software - FLUENT. The typical distribution of the velocity and temperature of the liquid nitrogen in the capillary tubes is obtained. The results show that the heat transfer performance is better when the inclination angles are 30 and 60 and the heat transfer performance in the 2.0mm diameter capillary tube is also better than that in 1.2mm diameter counterpart. Finally, the experimental data and the numerical results are compared, which shows quite reasonable agreement.