Explorations of multi‐pass‐orifice header in the liquid‐separation condenser by using CFD simulation

•Multi-pass-orifice header as liquid-separation unit is firstly explored.•Orifices on right side of baffle should be avoided due to strong fluid-impact.•Fluid-impact and liquid carrying contribute to vapor leakage in the orifices.•Separation efficiency is improved from 32.9% at Case 0 to 51.9% at Case 11.•Higher ∆P on orifice-baffle and less flow maldistributions are observed. Implementation of vapor-liquid separation during condensation enhances heat transfer and reduces pressure drop. Multi-pass-orifice header as a liquid-separation unit has been widely used in liquid-separation condenser (LSC). Its vapor-liquid separation characteristics, which are vital to LSC, are however barely reported. This paper employs CFD to reveal the flow features thereof. Simulation is initiated by applying an existing header in LSC (Case 0). Results show that the strong fluid-impact leads to considerable vapor leakage in orifices. By avoiding this, the orthogonal test (Case 1 to Case 9) is carried out to screen the orifice layout. It is observed the separation efficiency (η) is mostly affected by the orifice diameter, followed by its position and number. A better η is obtained when the orifices have diameter of 1.5 mm and are distributed on two thirds of header diameter (2D/3) as well as has the number of three (Case 5). Thereafter, two extra combinations of different orifice diameters (Case 10 and Case 11) are further studied. The obtained best η of 51.9% occurs at Case 11, in which it has a larger pressure difference (∆P) and more even flow distributions. Finally, some comments are addressed to pinpoint the significance of this study.