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열분배모델을 이용한 수직유로에서의 저압 미포화비등 해석

Numerical Study of Low-pressure Subcooled Flow Boiling in Vertical Channels Using the Heat Partitioning Model

  • 이바로 (제주대학교 에너지공학과) ;
  • 이연건 (제주대학교 에너지공학과)
  • Lee, Ba-Ro (Dept. of Nuclear and Energy Engineering, Jeju Nat'l Univ.) ;
  • Lee, Yeon-Gun (Dept. of Nuclear and Energy Engineering, Jeju Nat'l Univ.)
  • 투고 : 2016.02.21
  • 심사 : 2016.05.03
  • 발행 : 2016.07.01

초록

벽면비등 모델로 열분배모델을 채택하는 CFD 스케일의 전산해석코드는 저압 조건에서 미포화비등 발생 시 2상유동 변수의 해석 정확도가 낮은 것으로 알려진다. 본 연구에서는 열분배모델을 기반으로 벽면비등 현상을 예측하는 열수력 기기해석코드인 CUPID 코드를 이용하여 수직상향류 미포화비등 실험을 해석하였다. 10 bar 이상의 고압 조건에서는 CUPID 코드의 기포율 예측 정확도가 높았으나, 대기압 주변의 저압 조건에서는 기포율 분포에 대한 해석결과가 실험결과와 큰 차이를 보였다. 따라서 열분배모델 내 주요 인자에 사용되는 부모델에 대한 민감도 분석을 수행하였으며, 저압 조건 미포화비등 예측에 적합한 최적 부모델 조합을 선정하였다. 또한, 열분배모델 내 주요 인자 중 하나인 K-인자가 기포율에 미치는 영향을 평가하였다.

Most CFD codes, that mainly adopt the heat partitioning model as the wall boiling model, have shown low accuracies in predicting the two-phase flow parameters of subcooled boiling phenomena under low pressure conditions. In this study, a number of subcooled boiling experiments in vertical channels were analyzed using a thermal-hydraulic component code, CUPID. The prediction of the void fraction distribution using the CUPID code agreed well with experimental data at high-pressure conditions; whereas at low-pressure conditions, the predicted void fraction deviated considerably from measured ones. Sensitivity tests were performed on the submodels for major parameters in the heat partitioning model to find the optimized sets of empirical correlations suitable for low-pressure subcooled flow boiling. The effect of the K-factor on the void fraction distribution was also evaluated.

키워드

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