中文摘要：

为提高蒸汽换热器换热效率,提出了一种在水平换热管中插入芯棒的含芯棒蒸汽换热管结构,并通过采用Fluent中两相流模型分析该结构中芯棒直径对换热管管内冷凝换热特性的影响规律。研究结果表明,由于芯棒的插入使得管内两相流流体的平均流速与管道壁面附近速度梯度增大,故换热管的换热效率得到有效提升;定量而言,换热管的换热效率在棒径比值处于0.52~0.57区间范围内时,换热管内蒸汽冷凝率最高及通流截面内速度梯度最大,此时换热效率达到最高,可确保较低的换热管出口温度和稳定的换热效率。此外,场协同性能分析结果还表明,协同角与棒径比值呈正相关性,且当棒径比值0.52后,芯棒对水平换热管的强化传热效果明显。

英文摘要：

In order to improve the heat transfer efficiency of the steam heat exchanger,a mandrelcontaining steam heat exchanger tube structure of inserting a mandrel into a horizontal heat exchanger tube was proposed,and a two-phase flow model is built with commercial software FLUENT to analyze the heat exchange characteristics of the proposed heat exchanger tube. Simulation results show that as the insertion of the mandrel,the heat exchange efficiency of the proposed heat exchanger tube is improved by the increase of the average velocity and the velocity gradient near the tube wall of the two-phase flow.Quantitatively,the heat exchange efficiency has the maximum value while the ratio of mandrel diameter to the horizontal heat exchanger tube diameter is between the range of 0. 52-0. 57,and owing to higher condensation ratio and higher velocity gradient,it is ensured that temperature at the outlet of the heat exchanger tube is lower and the heat exchange efficiency is more stable. Meanwhile,according to the field synergy theory,the synergy characteristic increases as the increase of the ratio ε,and while the ratio is higher than 0. 52,the mandrel has obvious effect of enhancing the heat exchange ratio.