Effect of relative humidity on the nozzle performance in non-equilibrium condensing flows for improving the compressed air energy storage technology

Abstract

Compressed air energy storage (CAES) is now becoming the focus of a lot of research as it offers broad application possibilities and enormous economic benefits in terms of environmental protection and life with low-carbon emissions. The compressor performance is closely related to energy storage efficiency in CAES. Considering the significant role of water components inside the flow of the compressor, the flow mechanism in transonic with non-equilibrium condensation should be explored in detail. First, a blend condensation model is presented with the effect of the entire Knudsen number range on droplet growth, to explore condensation flow characteristics more clearly. Moreover, the influence of relative humidity (RH) on the nucleation and droplet growth and condensation shock wave is analysed with the blend model. Finally, flow loss is calculated in the de Laval nozzle, and the direction to optimize the compressor efficiency is indicated by considering the RH conditions and wall curvature arcs. The contribution of these factors to the flow loss deserves careful consideration. The analysis conducted in the paper shows the effect of relative humidity on the nozzle, and the conclusions obtained provide meaningful reference for improving the performance of compressors used in the CAES process in the future.