竖直矩形通道内不凝性气体对凝结换热特性的影响

本文以去离子水为工质,实验研究了竖直矩形窄通道内少量残余不凝性气体对蒸汽凝结换热特性的影响。采用热阻分离法得到凝结侧换热表面传热系数,分析了不凝性气体的含量、冷却水质量流速、进口温度和热流密度对蒸汽凝结侧表面传热系数的影响。结果表明:当热流密度为1.668 kW/m~2,即蒸汽质量流速较小时,2%体积分数的不凝性气体使凝结侧表面传热系数下降了33%,但当热流密度为3.887 kW/m~2,蒸汽质量流速较大时,2%体积分数的不凝性气体仅使凝结侧表面传热系数降低了14%,此外,凝结换热表面传热系数随冷水质量流速和不凝性气体分数的增加而变小,随冷水进口温度和热流密度的增加而变大。

Effect of Condensation Heat Transfer Characteristics of Non-condensable Gas in Vertical Rectangular Channel

The current experiment uses de-ionized water as a substance to investigate the influence of a small amount of residual non-condensable gas in a narrow rectangular vertical channel on the condensation heat transfer characteristics. The steam condensation surface heat transfer coefficient is obtained using the thermal resistance separation method, and the influence of non-condensable gas, cooling water mass flow rate, inlet temperature, and effective flux density on the steam condensation surface heat transfer coefficient is analyzed. The main results are as follows. When the heat flux density is 1.668 kW/m2, i.e., the steam mass flow rate is small, a 2% volume of non-condensable gas reduces the condensation surface heat transfer by 33%. However, when the heat flux density is 3.887 kW/m2, i.e., the steam mass flow rate becomes larger, a 2% volume of non-condensable gas only reduces the condensation surface heat transfer by 14%. In addition, the steam condensation surface heat transfer coefficient decreases as the volume percentage of the non-condensable gas increases. It also increases as the cooling water mass flow rate decreases and increases as the inlet temperature and effective flux density increase.