管长对UTSG倒流管空间分布的影响分析

Effect of U-Tube Length on Space Distribution of UTSG Reverse Flow in Tubes

自然循环条件下,自然循环U型管蒸汽发生器(UTSG)并联倒U型传热管内存在非均匀流动,部分传热管出现倒流;现有研究对倒流管的空间分布存在不同认识。通过建立一维、稳态条件下的传热管内流动换热模型,发现传热管管长对并联倒U型管间的流量压降对比关系产生影响,进而对倒流管的空间分布产生影响。传热管管长较小的UTSG,短管将先于长管发生流量漂移;反之,长管将先于短管发生流量漂移。采用最佳评估程序RELAP5/MOD3.3对研究结果进行了验证。

For natural circulation, it is shown that parallel flow in the tubes of inverted U-tube steam generators can be non-uniforga. And reverse flow occurs in some tubes. Existing studies on the space distribution of reverse flow tubes are dissident. A flow model of one-dimensional steady state is established. Analysis shows that the length will change the relationship of flow characteristics between tubes. And the space distribution of reverse flow tube differs further. When the U-tube length of UTSG is small enough, flow excursion will occur earlier in shorter tube than longer tube, and vise versa. And the analysis is validated by best estimate code RELAP5/MOD3.3.