Pressure drop in the printed cell
The pressure drop of the 3D printed electrolyzer without turbulence promoters was small and varied between 26 ± 2 mbar and 38 ± 2 mbar at Reynolds 1000 depending on the configuration (see also appendix figure A1). The highest pressure drop was found for the tube inlet, the lowest for the divider inlet. Since these differences are small, it is likely that their accuracy is strongly affected by the imperfections in the print and the gasket joints between components of the cell. Furthermore, because the pressure drop was measured across the entire electrolyzer, it may be possible that factors such as the placement of the external tubing or the tightness of the fittings lead to further inaccuracy. Turbulence promoters did not significantly affect the pressure drop. For the divider inlet without calming section, the pressure drop at Reynolds 1000 was 27 ± 2 mbar for every promoter (see also appendix figure A2). In the cell with divider inlet and a 150 mm calming section, the pressure drop for varied between 27 ± 2 mbar and 35 ± 2 mbar for the promoters compared to 22 ± 2 mbar in the empty channel. Generally, a trend exists wherein the better performing turbulence promoters cause a higher pressure drop, though the difference is small.