Design analysis of a liquid-piston compression chamber with application to compressed air energy storage

The present study focuses on a design analysis of a shaped liquid piston compression chamber based on CFD. The liquid piston compression chamber is for application to Compressed Air Energy Storage (CAES), which can be used to even the mismatch between power generation and power demand, and, thus, the objective of the design exploration is to maximize the compression efficiency. Within the compression chamber is an open-cell metal foam medium for enhancement of heat transfer. Traditionally, the chamber has a cylindrical shape. The present study explores the effects on compression efficiency of varying the profile of cross-sectional diameter along the axis of the chamber. This leads to a compression chamber with curved walls that assume a gourd-like shape. A set of exploratory design cases is completed using the orthogonal array concept based on the Taguchi method, hence reducing the number of realizations. CFD simulations provide insight into how the chamber shape affects the flow physics during compression. A quantitative design analysis shows that, in general, a large aspect ratio and a steep radius change of the chamber is preferred, which is in line with a visualization of the CFD flow fields. The relative importance of each different shape parameter is analyzed.