Comparisons of oxygen increment in a micropump considering the dissolved and released processes

Space micropump are an important component of the on-orbit refuelling system. The gas-liquid behaviour transition induced by dissolved and released processes in the micropump has obtained considerable attention. Our proposed mathematical model achieved the bidirectional dissolved-released processes in an on-orbit space micropump for the first time. The performance characteristics of the micropump and the mathematical computational model used by the plug-discharge flow have been validated. Herein, the correlated mechanism between the flow, mass transfer and solution status were analysed. Under the pressurization of the micropump impeller, the gas was constantly dissolved into the solution, and the higher concentration caused the gas to evolve from the solution. The oxygen increment decreased rapidly when the initial dissolved oxygen centration exceeded 23 mg/L because of the gas evolution occurred. Focused on this sudden decreasing state of oxygen increment from 23 to 24 mg/L, four concentration conditions were discussed in depth including flow field, oxygen increment and mass transfer rate. In the impeller, the equilibrium concentration increases controlled by the pressure was obviously larger than the increase of the real-time concentration; thus, the unidirectional absorbed processes occurred inside the impeller. Two near-rate mass-transfer band were found near the short blades, exhibiting the dynamic equilibrium characteristic. Moreover, affected by the strong disturbance of the impeller outlet, the mass transfer rate was the highest here.