Two-phase flow behavior inside a header connected to multiple parallel channels

The main objective of this work is to examine the flow distribution of two-phase mixture to parallel channels and to investigate the flow behavior at header-channel junctions simulating the corresponding parts of compact heat exchangers. The cross-section of the header and the channels were fixed to 14 mm × 14 mm and 12 mm × 1.6 mm, respectively. The mass flux and the mass quality ranges were 70–165 kg/m2 s and 0.3–0.7, respectively. Air and water were used as the test fluids. The flow distribution at the fore part of the header (region A) is affected only by the upstream flow configuration and the rate of liquid flow separation decreased a flowing downwards. On the other hand, in the rear part, the downstream effect predominates over the upstream effect due to strong flow recirculation near the end plate. In this part, the liquid separation increased (region B) and then decreased (region C) as the mixture proceeds downwards. The validity of the existing models for branching flows at parallel T-junction was tested, and turned out to be appropriate for region A. However, the models were not applicable to the rear part due to a strong flow recirculation. Moreover, the effect of the membranes in channels was investigated, but that was minor.