INFLUENCE OF COMPOSITION ON HEAT TRANSFER AND CRITICAL HEAT FLUX IN BOILING OF MULTICOMPONENT MIXTURES

(1)气泡生长模拟程序的开发开发了一个数值模拟程序，用于分析单个成核点和两个相邻点的气泡生长和聚并。模拟结果明确了气泡下半月板膜蒸发的重要性。(2)混合成分对流动沸腾的影响采用水平管对二元制冷剂（R-134a/R-124）进行了流动沸腾实验。压降不受混合物成分的影响，但混合物沸腾时传热明显减少。测得的压降和换热数据以经验相关关系进行相关。(3)混合物组成对三组分混合物的影响在核池沸腾中测量了R-134a/R-142b/R-123三元制冷剂混合物的传热系数。传热系数的减小可归因于有效温差的减小，这是由于在液-气界面上挥发性较强的组分的耗尽造成的。因此，沸点范围被认为是一个主要参数，并被引入到混合物沸腾传热系数的关联中。

(1) Development of Simulation Code for Bubble GrowthA numerical simulation code was developed to analyze the bubble growth and coalescence both for a single nucleation site and for two neighboring sites. Simulation results made clear an importance of evaporation from a meniscus film under bubbles.(2) Influence of Mixture Composition in Flow BoilingFlow boiling experiment was performed for binary refrigerant mixtures (R-134a/R-124) in a horizontal tube. Pressure drop was not influenced by mixture composition, while heat transfer was significantly reduced in mixture boiling. Measured data of pressure drop and heat transfer were correlated in empirical correlations.(3) Influence of Mixture Composition on Three Component MixturesHeat transfer coefficient of ternary refrigerant mixtures (R-134a/R-142b/R-123) was measured in nucleate pool boiling. Reduction in heat transfer coefficients was found attributable to a decrease of the effective temperature difference as a result of the depletion of the more volatile component at the liquid-Vapor interface. Thus the boiling range was considered as a dominant parameter and introduced in a correlation for boiling heat transfer coefficient of mixtures.