| Summary: | 碩士 === 國立中正大學 === 機械工程學系暨研究所 === 102 === All-vanadium redox flow batteries (VRBS) are energy storage devices using vanadium ions to store energy. They are combined with renewable energy systems to stabilize power output. During electrochemical reaction the concentration of reactive vanadium varies along flow direction. A small electrolyte flow rate increases the concentration overpotential near the outlet of active area. The concentration overpotential can be reduced by increasing electrolyte flow velocity or flow rate. The flow velocity. Increases with decreasing aspect ratio of reaction area; however, pressure drop is also increased, resulting in increasing power consumption of pumps and lowering net power output.
In this study a mathematical model was developed to investigate the effect of aspect ratio of the active area on battery performance. In addition, the mass transport overpotential due to variation of electrolyte concentration was coupled in the model. The distributions of local current density and electrolyte concentration along flow channel were presented and discussed. Power consumption of pumps was determined according to pressure drop and electrolyte flow rate and used to calculate the net power output of a VRB. Modeling results showed that although a low aspect ratio of reaction area increased battery performance due to high electrolyte flow velocity, the power consumption of pumps also increased due to high pressure drop. This model helps design the active area and determine the operating condition of a VRB system.
|
|---|
