The implementation of vapor-liquid separation during condensation enhances heat transfer and reduces the pressure drop simultaneously. The vapor-liquid separator is vital for the performance improvement of such liquid-separation condensers. This study focuses on a header baffle with a small hole as the vapor-liquid separator. A 3D numerical model for the separator was established to investigate the vapor-liquid separation characteristics. The model was validated by experimental data first

and then it was used to analyze the effects of hole diameter (0.5–2 mm) and hole position (centered or not) on the flow features of the working fluid in the header. The results showed that when the inlet mass flow rate was 3 g/s and the inlet vapor quality was 0.5

the liquid-separation efficiency and vapor drainage ratio increased with increasing hole diameter. The best performance is achieved when the hole diameter is 1.6 mm and centered. In this case

the liquid-separation efficiency was up to 70.23%

and the vapor drainage ratio was 0.14%. The hole position mainly affects the velocity and pressure distributions. It was found that the vapor-liquid inertial force ratio can reach up to 1.51×10-2 as the hole diameter is 2 mm and its position is not centered. Hence

the unreasonable arrangement of hole diameter and position could lead to “fluid impact” at the liquid-separation hole.