VISCOUS EXPANDER

To make a small refrigerator with high efficiency, small refrigeration power and a low vibration level at low temperatures, an expander is i ntroduced and theoretically investigated. This expander uses fluid vis cous forces to drag a rotor, thus causing it to rotate and produce wor k, and therefore to generate refrigeration power. Analyses of the dyna mic and thermodynamic processes of fluid flow in the expander have bee n carried out. Analytical expressions of output power with adiabatic e xpansion efficiency in terms of the geometric and hydrodynamic paramet ers are derived from viscous theory. The effects of the geometric and thermodynamic parameters of the performance of the expander are discus sed. As an example, 41.5% of adiabatic efficiency and 6.2 W of output power are achieved with the expander at 20 K, according to our calcula tions. Calculations show that the expander would be a promising machin e for use in a small refrigerator because of its high efficiency and s mall flow rate.