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混合蒸気の濃度差マランゴニ凝縮における赤外レーザー吸光法による凝縮液厚さ測定

利用红外激光吸收法测量马兰戈尼凝结中由于混合蒸汽浓度差而产生的凝结水厚度

基本信息

批准号：
12650194
负责人：
宇高義郎
金额：
$ 2.3万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

"Positive system"と呼ばれる低沸点成分に比べて高沸点成分液の表面張力の大きい混合蒸気系の凝縮過程において、濃度差表面張力不安定によって、表面の温度分布に起因する濃度・表面張力分布が生じ,擬似的な滴状凝縮などの凝縮液形態が出現する。凝縮液抵抗は低減し、伝熱性能の飛躍的な向上が見られる条件が比較的広範に現れる。本研究は、濃度差マランゴニ凝縮現象の熱伝達機構・特性を解明するため、波長3.39μm赤外レーザー光の吸収特性を用いる新たな方法により、本現象における凝縮液膜厚の変化特性の精密測定を行うことを目的として、以下の結果を得た.(1)水-エタノール混合液体の消光性質を明らかにした.(2)レーザ光の集光により,微小な薄液膜部寸法に対応する直径約30μmのレーザ光照射寸法を実現した.(3)液膜厚さ測定位置と凝縮液挙動の対応関係を明確にした.(4)本測定の液膜厚さ1μm程度の測定へ適用可能であることを示した.さらに、(5)液膜厚さと凝縮液挙動の同時観測により,離脱液滴による掃除後の薄液膜および液滴間薄液膜の厚さ変化の測定を行った.(6)低過冷度領域から初生液滴間隔の減少に伴い最小液膜厚さは減少する傾向を示し,さらに冷却強度を増大させると,初生液瀧間隔および最小液膜厚さとも増大した.(7)最小液膜厚さは濃度の減少に伴って減少し,本測定の範囲においては約1μmであった.(8)本研究と既報の結果から,極大熱伝達率付近の過冷度域で,初生液滴間隔,離脱液滴直径,最小液膜厚さとも最小となることなど,凝縮特性曲線における熱伝達率変化特性とそれらの特性量変化の間には類似の対応関係が存在していた.(9)上記(8)から,熱伝達率のピーク付近で駆動力は最も強まると推測され,凝縮液膜は薄膜化し,その結果としての凝縮液熱抵抗の減少が熱伝達率向上の主要因の一つとなっていることが結論される.

"Positive system" is a high-boiling-point component liquid with a low boiling point component, a large surface tension, a mixed evaporation system, a condensation process, and a concentration difference surface The unstable tension and the temperature distribution on the surface are caused by the concentration and surface tension distribution, and the pseudo-droplet condensed liquid form appears. The condensate resistance has been reduced, and the thermal performance has been greatly improved by comparing the conditions and conditions. This study explains the mechanism and characteristics of the heat transfer phenomenon of concentration difference malcondensation phenomenon, wavelength 3.3 9μm infrared light absorption characteristics, using the new method, this phenomenon is based on the condensed liquid film thickness According to the precise measurement of chemical properties, the following results have been obtained. (1) Water - water The matting properties of the mixed liquid are bright and clear. (2) The light-gathering properties of the light mixture are small and thin liquid film parts. The measurement position of the liquid film thickness is determined by measuring the thickness of the liquid film by irradiating the light with a diameter of about 30 μm. The relationship between the condensation liquid and the movement of the condensate is not clear. (4) This measurement is suitable for measuring the liquid film thickness of less than 1 μm. It can be used to measure the thickness of the liquid film and the movement of the condensed liquid at the same time. Measurement of the thickness of the thin liquid film between the droplets after removal of the liquid droplets and the change of the thickness of the thin liquid film after cleaning. (6) Lower than In the coldness field, the distance between primary droplets is reduced, and the minimum liquid film thickness is reduced, and the tendency is to show that it is cold. However, the intensity has increased, the initial liquid interval has increased, and the minimum liquid film thickness has increased. (7) Minimum liquid film The reduction in thickness and concentration is accompanied by a reduction in thickness, and the measurement range of this measurement is approximately 1 μm. (8) The results reported in this study include the maximum heat arrival rate, the supercooling range close to the maximum heat arrival rate, the distance between primary droplets, and the diameter of the detached droplets. , Minimum liquid film thickness, minimum liquid film thickness, minimum liquid film thickness, condensation characteristic curve, thermal expansion rate changing characteristics,れらの Characteristic quantity change の间には is similar to the の対応 relationship がexistent していた. (9) Above (8) から, 热伝The highest rate of success, the most powerful power, the best guess, the condensed liquid film, the thin film, and the result. The main reason for the decrease in the thermal resistance of the condensate is the increase in the heat uptake rate.