Pumping mechanism using periodic phase changes of a fluid

Abstract

A new pumping mechanism using the large differences of thermal properties of a fluid between liquid and vapor phases has been developed. Altemate phase changes of a fluid cause variations of the saturation pressure and specific volume of the fluid. Also, they vary the viscous forces in flows in a narrow channel. Using these alternate phase changes of a fluid functionally, we can achieve pumping action on the fluid. This pumping mechanism has aptitudes for micro-pumping devices because the pumps based on this mechanism are simple in structure and they require no mechanical moving parts. Besides these advantages on manufacture, this mechanism is expected to operate more cleanly in smaller systems. This is because, the smaller systems have smaller thermal time constants, and the viscous forces have larger influence in the smaller flows. This pumping mechanism was proved experimentally with water in straight stainless steel capillaries.