The reflux condensation phenomenon in steam generator U-tubes, which may be an important heat removal mechanism in a certain phase of small break loss of coolant accident in nuclear power plants, has been investigated.
The flow pattern is an important factor of heat removal capability. In the present work, a series of experiment have been performed to establish the basic modes of reflux condensation.
Basically, three modes have been identified which is in complete agreement with the previous workers. Three basic modes are the filmwise reflux condensation mode, the complete reflux condensation mode and the thermosyphoning mode.
Experimental results that have been obtained under the filmwise reflux condensation mode are compared with the Nusselt condensation theory. In addition, to examine the effect of cooling water temperature on the reflux condensation lengths, two series of tests were made at two different coolant temperature levels.
Finally, transition criteria between the three reflux condensation modes were experimentally investigated while changing the inlet steam flow rate.
원자로 소냉각재 상실 사고시 중요한 열제거 기작인 증기 발생기 내에서의 역류 응축 현상 (Reflux Condensation Phenomenon)에 대한 연구를 수행하였다.
흐름의 형태는 열제거 능력의 중요한 요소가 된다. 따라서, 역류 응축의 기본적 형태를 설정하였다. 세가지 기본적 형태는 막 역류 응축 형태, 완전 역류 응축 형태, 그리고 Thermosyphoning 형태이다. 막 역류 응축에서의 실험 결과를 Nusselt 응축 이론과 비교하였고 냉각수에 의한 효과를 알아보기 위하여 냉각수 온도가 다를 때의 실험 결과 차이를 알아보았다.
유입 증기량의 변화에 따른 각각의 역류 응축 현상의 천이 경계에 대하여 알아보았다.
