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首页> 外文会议>The 2001 ASME International Mechanical Engineering Congress and Exposition, 2001, Nov 11-16, 2001, New York, New York >HEAT TRANSFER AND CRITICAL HEAT FLUX OF FORCED FLOW BOILING IN VERTICAL-NARROW-ANNULAR PASSAGES
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HEAT TRANSFER AND CRITICAL HEAT FLUX OF FORCED FLOW BOILING IN VERTICAL-NARROW-ANNULAR PASSAGES

机译：竖向-环形-环形通道中强迫流动沸腾的传热和临界热通量

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摘要

The forced-convection flow boiling heat transfer in narrow-annular flow passages was experimentally examined by using R-113. The gap clearance and the mass flux were δ = 0.5～10.0 mm and G = 10~2 ～ 10~3 kg/m~2s, respectively. When the clearance was narrow (δ = 0.5 and 1.0 am), the critical heat flux (CHF) condition which was defined as the deviation from the fully developed nucleate boiling state occurred in the first place, then the wall temperature excursion (EXC) was initiated after a further increase in the heat flux. At the CHF condition, the wall temperature did not rise sharply. The difference between those heat fluxes, q_(CHF) and q_(EXC), became small as the flow rate was increased. When the clearance became wide (δ ≥ 2.0 mm), the CHF condition and the EXC occurred simultaneously. The EXC heat flux q_(EXC) increased sharply with an increase in δ until δ = 2.0 mm. In δ > 2.0 mm, the increasing rate calmed down to show tendency reaching some asymptotical value, q_(EXC) of the co-current flow was considerably higher, approximately ten times, than q_(EXC)- of the counter-current flow. The difference decreased as δ became wide. The critical heat flux, q_(CHF), correlation, which was developed by considering that whether the dried area which was created because of wearing-out of the liquid layer under a bubble could be rewetted or not decide the critical condition, predicted well the present experimental results of q_(CHF). However, when 5 was extremely narrow such as δ = 0.5 and 1.0 mm, the heat transfer deterioration due to the appearance of a coalescent bubble occurred before the condition defined above, thus the correlation overpredicted q_(CHF).
机译：通过使用R-113实验研究了窄环形流动通道中的强制对流沸腾传热。间隙间隙和质量通量分别为δ= 0.5〜10.0 mm和G = 10〜2〜10〜3 kg / m〜2s。当间隙较窄时（δ= 0.5和1.0 am），首先发生临界热通量（CHF）条件，该条件被定义为与充分发展的核沸腾状态的偏差，然后壁温偏移（EXC）为在热通量进一步增加之后开始。在瑞士法郎条件下，壁温没有急剧上升。随着流量的增加，这些热通量q_（CHF）和q_（EXC）之差变小。当间隙变宽（δ≥2.0 mm）时，CHF条件和EXC同时发生。 EXC热通量q_（EXC）随着δ的增加而急剧增加，直到δ= 2.0 mm。在δ> 2.0 mm时，增长率趋于平稳，显示出趋于达到一些渐近值的趋势，并流的q_（EXC）比逆流的q_（EXC）-高得多。随着δ变宽，差减小。临界热通量q_（CHF）相关性是通过考虑是否可以重新润湿由于气泡下液体层的磨损而产生的干燥区域或不决定临界条件而得出的，该预测很好地预测了目前q_（CHF）的实验结果。但是，在δ＝ 0.5、1.0mm等5个极窄的情况下，在上述条件之前就发生了由于聚结气泡的产生引起的传热劣化，因此相关性过高地预测了q_（CHF）。

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