弹性管束外液膜强制诱导波动蒸发换热机理分析
Mechanism Analysis of Forced Induced Wave Evaporation Heat Transfer by Liquid Film outside Elastic Tube Bundle

本文建立了弹性管束外液膜强制诱导波动蒸发实验台，通过实验与数学分析相结合的方法研究弹性管束间两相流传热传质机理。实验通道宽度为0.5~2.0 mm。重点研究两相流流型、压力损失和通道宽度与传热特性之间的关系。实验中观察到三种流动状态，分别为泡状流、限制泡状流和蒸干区。在相同宽度的通道中，过冷沸腾的初始热流随流量的增加呈线性增加。在相同流速下，过冷沸腾的初始热流随通道宽度的增加而减小。气泡产生频率和脱离直径对壁面传热系数有明显影响。但气泡产生频率的增加也会导致气泡分离直径的减小。通过数学分析，发现通道尺寸的变化会影响传热系数，但在强化和弱化换热之间存在一个边界。该研究的理论值与实验值的比较结果吻合较好。
An experimental platform for forced-induced wave evaporation of liquid film outside the elastic tube bundle was established in this paper. The mechanism of two-phase heat and mass transfer between the elastic tube bundle was studied by combining experiment and mathematical analysis. The experimental channel width was 0.5~2.0 mm. The relationship between the flow pattern, pressure loss, channel width and heat transfer characteristics of two-phase flow is studied. Three flow states were observed in the experiment, namely bubble flow, restricted bubble flow and drying zone. In a channel of the same width, the initial heat flow of subcooled boiling increases linearly with the increase of the flow rate. At the same flow rate, the initial heat flow of subcooled boiling decreases with the increase of channel width. Bubble generation frequency and detachment diameter have an obvious influence on wall heat transfer coefficient. However, the increase of bubble generation frequency also leads to the decrease of bubble separation diameter. Through mathematical analysis, it is found that the change in channel size will affect the heat transfer coefficient, but there is a boundary between enhanced and weakened heat transfer. The theoretical values of this study agree well with the experimental values.