Computational and experimental investigation of condensation flow patterns and heat transfer in parallel rectangular micro-channels. (March 2020) - Lei, Yuchuan
Highlights: A 3-D computational model is constructed to predict condensation in micro-channels. Predicted are flow patterns, micro-channel wall temperature, and fluid temperature. Predictions are validated using experimental data for FC-72. Good model accuracy is achieved in predicting both flow patterns and wall temperature. Abstract: This study explores experimentally and computationally fluid flow and heat transfer characteristics of FC-72 condensation along a cooling module containing multiple 1 mm × 1 mm square channels. The module is cooled along its underside by a counterflow of water. The computational portion of the study adopts the VOF method and Lee interfacial phase change model, and is executed using ANSYS FLUENT. Computed are dominant flow patterns as well as spatial variations of both bottom wall temperature and fluid temperature for FC-72 mass velocities ranging from 68 to 367 kg/m 2 s. The computed flow patterns show good agreement with those captured experimentally using high-speed video. Captured correctly are dominant smooth-annular, wavy-annular, transition, slug, bubbly, and pure liquid flow patterns. And predicted variations of wall temperature show good agreement between computational results, with average deviation ranging from 1.46% to 6.81%. The computational method is capable of predicting fluid temperature, which cannot be measured experimentally in a small channel. Detailed spatial variations of fluid temperature are provided both perpendicular to the bottom wall and along the channel. These variations show close correspondence with axial spans of the dominant flow patterns.