LNG管内强化传热技术

Analysis on technique of heat transfer enhancement of LNG in tubes

采用数值分析方法研究液态天然气(LNG)分别在圆管与螺旋扁管流体中的流动状态与传热效果。模拟结果表明:螺旋扁管内因特殊管壁形状诱发产生了纵向涡,导致流体在管内做螺旋运动;在雷诺数相等时,螺旋扁管强化传热倍数均大于1.0,最高达1.50,管内的平均温度也更高,其强化传热效果优于圆管;压降倍数变化趋势与强化传热倍数一致,最高可达圆管的2.57倍;在螺旋扁管的过渡流段中,流体的综合强化传热效果较好,综合评价因子最高达1.50。

The fluid flow state and heat transfer effect of liquid natural gas(LNG) in circular pipes and spiral flat tubes were studied by means of numerical analysis. The simulation results show that the longitudinal vortices are caused by the shape of the special tube in the spiral flat tube, which makes the fluid be in a spiral motion in the tube. When the Reynolds numbers are equal, the spiral pipe strengthens the heat transfer factor Nu’above 1.0, up to 1.50, and the average temperature in the tube is higher, indicating that the enhanced heat transfer effect is better than that of the circular tube. The decreasing trend of pressure drop multiple is consistent with the enhanced heat transfer factor, with the value up to 2.57 times that of the circular tube. The comprehensive heat transfer effect of the spiral flat tube in the transition flow sounds good, and the comprehensive evaluation factor is up to 1.50.