Numerical Study of Pressure Drop in Stirling Engine Regenerator

Abstract

The regenerator of a β-type Stirling engine is simulated with computational fluid dynamics. Emphasis is given to the drop in pressure caused by friction during gas flow through the regenerator matrix. The primary results include the temporal variation of the mass-flow rate and velocity in different levels of the regenerator. A time interval of between 5% and 10% of the engine cycle was found, during which gas is flowing inward to or outward from the regenerator from both its sides. Both gas velocity and pressure drop per unit length is found to increase in hotter sections. The friction factor is extracted and correlated with Reynolds number. Furthermore, two correction factors are applied to the coefficients of viscous and inertial resistance of the Ergun equation. Finally, the temporal and spatial change of the pressure drop is examined for the studied engine. An equation that well estimates the value of the pressure drop for a given time and regenerator length is presented. The derived equation can be used as input data to improve a simple analytical model.