Abstract
A stackable Knudsen pump consisting of multistage pump units driven by temperature difference between hot and cold water is fabricated. Each unit has a porous membrane of 64 cm2 area, through which thermal transpiration flow, the driving force of the Knudsen pump, is induced at atmospheric ambient pressure. This study demonstrates the present device facilitates the cascade or parallel connection of multiple pump units to improve performance. For example, a Knudsen pump consisting of 6-cascaded units provides a shut-off pressure of 9.2 kPa and a 300 sccm maximum flow rate at the temperature difference of 45 K. The feasibility of the pumping system driven by low-grade waste heats is also demonstrated.
