科研之友
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摘要
In this paper, condensation flows in a cross-flow air-cooled microcondenser were investigated for mass velocity lower than 12kg m(-2) s(-1), with n-pentane used as working fluid. The microcondenser consisted mainly of a transparent square-cross-section microchannel placed horizontally, having inner and outer edges of 553 and 675m, respectively, and a real length exposed to the coolant of 196mm. One of the features of the experimental bench was the choice of the air as coolant. The external heat transfer is thus limiting, which allows imposing a heat flux and consequently an almost linear variation of the vapor quality according to the axial position in the microchannel. Three flow zones were mainly identified: the annular zone, the intermittent (i.e., elongated bubbles or slug-bubbly) zone, and the spherical bubbles zone. A specific experimental procedure based on bubbles tracking was developed in order to determine the hydraulic and thermal parameters in the intermittent zone. The mean displacement and condensation velocities of the elongated bubbles were determined according to their mean length for different mass velocities of the n-pentane. Also, the mean latent heat flux released by the condensation of the elongated bubbles was determined according to their mean surface for different mass velocities of the n-pentane, and was compared to the imposed heat flux.
- 出版日期2016-9-21
- 单位中国地震局
