New laser based method for non-intrusive measurement of available energy loss and local entropy production

Abstract

This paper outlines a new experimental technique for measuring the instantaneous entropy production using a non-intrusive, laser based approach. Unlike point-wise methods which yield measured velocities at single points in space, the method of PIV (particle image velocimetry) is used to derive the spatial velocity gradients over the entire problem domain. When combined with local temperatures and thermal irreversibilities, these velocity gradients can be used to determine the energy availability loss due to exergy destruction. This article focuses on frictional effects, which lead to irreversible degradation of mechanical energy into internal energy through viscous dissipation. Frictional effects are significant in various devices, ranging from power turbines, internal flow systems and other turbomachinery. In addition to measured data for validation of predictive models, such data can be used by designers to characterize and improve the energy efficiency of engineering devices.