The HETP values for the TRP column are consistent with a previous study²⁷ that used similar random packing for nitrogen-argon separation. HETP values for the PTL column are lower, while those for the AMPH column are the lowest (3.2 cm for nitrogen, 3.3 cm for argon). Thus, the AMPH column is the most effective of the three. This increase in separation efficiency with the same column height is an example of process intensification through improvement of the gas liquid interface in the column.

Figure 9 shows how the result for the AMPH column (3.2 cm) is consistent with HETP values from previous PNNL MCD studies. In general, HETP values increase with mass flux.