Performance and flow characteristics of the liquid turbine for supercritical compressed air energy storage system

Abstract

• Geometrical models of liquid turbines affect the accuracy of predicted efficiency. • The model with a nozzle and a rotor predictes the efficiency with 15.8% error. • The total pressure loss of the rotor accounts for the largest portion among all parts. • The nonuniform flow in the nozzle and the rotor is significant at low flow rates. The liquid turbine can replace throttling valves during the depressurization process of high-pressure liquid or supercritical fluid and improve the system efficiency of many industrial systems. However, there is no research about studying the internal flow and total pressure loss of liquid turbines, which can affect the turbine performance significantly. In this paper, performance and flow characteristics in a liquid turbine were analyzed for supercritical compressed air energy storage (SC-CAES) systems in the first time. Three typical topology models (C1, C2 and C3) of the tested liquid turbine were simulated and their performances were compared with experimental results. The deviation of the turbine efficiency between C3 and the experiment was less than 2%, while C1 had a constant increment of the turbine efficiency about 15.8% with the experiment. The total pressure loss in each part was evaluated and the flow characteristics in the nozzle and the rotor were analyzed. Nonuniform flow affected the nozzle’s total pressure loss significantly, while the rotor’s total pressure loss was related to the development of low energy regions. The results obtained in this paper provides guidance for optimizing liquid turbines and improving the turbine performance for various industrial systems with throttling valves installed.