A Novel Gas Divider using Nonlinear Laminar Flow

Gas dividers are important in emissions measurement since they continuously and accurately mix two gases to create a known gas concentration that is needed in the multi-point calibration of gas analyzers. A novel gas divider was designed using nonlinear laminar flow induced from the density change along the capillary channels due to the high-pressure drop (relative to the inlet gas pressure). The minor losses from entrance and exit effects can be ignored due to the high pressure loss from Hagen-Poiseuille's law relative to the minor losses. Small diameter wires inside of a tube were used to create capillary channels through which gas could flow. The gas divider, using nonlinear laminar flow, showed lower measurement uncertainty at high (90%) dilution levels than using linear laminar flow due to the higher-pressure drop at the same volumetric flow rates. Experiments showed the expected gas concentration from using the gas divider to be within 2% of the measured gas concentrations.