On the prediction of ultimate separation in parametric pumps

Quantitative theories based on first principles are derived to explain the roles of heat and mass transfer in the attainment of steady state or ultimate separation in closed direct‐thermal‐mode parametric pumps. The theoretical results are in agreement with applicable experimental data, including the experimental anomaly called reversed separation. Under conditions when the axial dispersion is much greater than molecular diffusion, the theory predicts and experiments confirm that 1/ln(α∞) varies in a linear way with fluid displacement at constant frequency. An additional asymptotic result suggests that when Sh » PeM, there is a simple linear connection between 1/ln(α∞) and PeM which is supported by experimental data.