压水堆冷凝回流特性的研究

利用高压汽水两相流试验系统模拟压水堆小破口失水事故中冷凝回流传热模式，进行了传热、流动及不凝结气影响的试验。实验表明：冷凝回流传热是一种十分有效的传热模式，它在很小的一、二次侧温差时就能排放大量堆芯余热。冷凝回流系统在正常情况下流动阻力很小且稳定，但在达到回流流动极限后出现不稳定。不凝结气的存在将大大降低蒸汽发生器的传热能力，但一般情况下，系统能自动增加一次侧压力而达到排除余热的目的。

AN INVESTIGATION ON PWR REFLUX CONDENSATION CHARACTERISTICS

In the high pressure steam-water two-phase fiow test system of Xi'an Jiaotong University, the refiux condensation characteristics at PWR SBLOCA are simulated success-fully. In experiments, the heat transfer, flow and noncondensable gas effect are determined.From the tests, the reflux condensation heat transfer is very effective to remove the reactor core decay heat under small temperature difference. Generally, reflux condensation's flowresistance is small and flow is stable. But when coulltercurrent flow limit is reached, the flow will change to be instable. Noncondensable gas can degrade the heat transfer ability in steam generator, but system can increase the pressure in reactor automatically to remove the decay heat when only a little noncondensable gas ekists.