关键词: 透明导电膜, 升膜蒸发, 流型, 传热系数

Abstract: In order to explore the effects of the heat flux density,vacuum degree and flow on heat transfer performance of climbing film evaporator,this paper observed and analyzed the fluid flow pattern in the climbing film heating pipe,established the heat transfer experimental platform of climbing film evaporation system,and studied the heat transfer characteristics and fluid flow pattern of climbing film evaporator. The length of the climbing film evaporation pipe used in the experiment was 2200mm,the climbing film pipe was a quartz tube coated with transparent conductive film,the working medium was water,and electrical heating was employed in the evaporation section. The effects of the heat flux densities(6.71kW/m²≤ q≤ 26.79kW/m²),flow rates (20L/h≤ M≤ 100L/h) and vacuum degrees(0≤ P≤ 15kPa) on fluid flow pattern and heat transfer characteristics of the climbing film heating pipe were studied. The results showed that climbing film evaporation for the solution in the quartz pipe could be achieved in the way of electric heating. And bubbly flow,bulk flow,slug flow,plug flow,annular flow and mist flow were observed. When heat flux was less than 6.71kW/m²,climbing film evaporation was not formed. With the increase of the evaporation side heat flux density,annular flow length increased in the climbing film pipe,and the inner pipe heat transfer coefficient increased. With the increases of the flow,liquid turbulence intensity increased inside the climbing film pipe,the inner pipe heat transfer coefficient increased as well. And vacuum degree had a significant influence on the fluid flow pattern.

Key words: the transparent conductive film, climbing film evaporation, flow pattern, heat transfer coefficient