CAJ | 학술논문

通过可视化实验研究了含空气蒸汽泡的冷凝行为和传热特性，气泡中蒸汽质量含量在0.5～0.8之间。在两种不同的过冷水温度下，混合气体气泡分别由直径1.5 mm和3 mm的喷嘴以不同的速度喷入静止的过冷水空间中。通过高速摄像机记录气泡冷凝过程，通过气泡体积变化状况计算气泡热力学参数，进而计算气泡的冷凝传热系数。结果表明，气泡在冷凝过程中不断变形，且在冷凝开始时，气泡出现中空现象；冷水温度越低，冷凝传热系数越低；气泡体积越大，冷凝传热系数越低；喷嘴直径对冷凝传热影响不明显；不凝气体的加入恶化了冷凝传热。对实验中65个气泡传热系数的数值进行了拟合，获得了传热系数关联式。
통과가시화실험연구료함공기증기포적냉응행위화전열특성，기포중증기질량함량재0.5～0.8지간。재량충불동적과랭수온도하，혼합기체기포분별유직경1.5 mm화3 mm적분취이불동적속도분입정지적과랭수공간중。통과고속섭상궤기록기포냉응과정，통과기포체적변화상황계산기포열역학삼수，진이계산기포적냉응전열계수。결과표명，기포재냉응과정중불단변형，차재냉응개시시，기포출현중공현상；랭수온도월저，냉응전열계수월저；기포체적월대，냉응전열계수월저；분취직경대냉응전열영향불명현；불응기체적가입악화료냉응전열。대실험중65개기포전열계수적수치진행료의합，획득료전열계수관련식。
The condensation behavior and heat transfer characteristics of steam bubbles with air were investigated by visual experiments, with steam mass fraction between 0.5 and 0.8. Bubbles of gas mixture were injected into cool water at two different temperatures through nozzles of diameter 1.5 and 3 mm. The condensing processes of bubbles were recorded by high speed camera and the thermodynamic parameters of bubbles were obtained by the variation of bubble volumes, from which the condensing heat transfer coefficients were calculated. The results show that the bubble deforms continuously when it condenses and a hollow forms in the middle of the bubble at the beginning of the condensing process. The condensing heat transfer coefficient decreases as cool water temperature decreases and bubble volume increases, while it is not affected by the nozzle diameter. The condensing heat transfer is deteriorated by the noncondensing gas. A correlation to predict the heat transfer coefficients is established using all the 65 data obtained in this experiment.