A Three-Dimensional Model for Thermal Analysis in a Vanadium Flow Battery

Abstract

The development of vanadium flow battery (VFB) has expanded the possibilities for large-scale energy storage in confronting against the conventional energy’s challenges. With the development of commercialization of VFBs, more focuses should be switched to probe deeply into the fundamental processes inside a VFB and develop practical tools to aid controlling/monitoring the VFB system. Whereas, achieving the above objectives via extensive laboratory testing is time-consuming and costly. In pilot studies, modelling can be a promising substitute. Heat and temperature need to be considered seriously in the VFB design and control for an efficient and safe operation. In this regard, a three-dimensional model for thermal analysis in a VFB was proposed to provide a deep insight into heat source of heat generation and temperature in a VFB. The model is a combination of mass, momentum, charge, energy transport and electrochemical reactions involving all vanadium species. A quasi-static thermal behaviour and the temperature spatial distribution were characterized. The simulations indicate that the heat generation exhibits a strong dependence on the applied current density. The electrochemical reaction heat rises proportionally while the ohmic heat and activation heat increase at a parabolic rate with the increase of applied current density, resulting in the determining heat source’ varying from electrochemical reaction heat to ohmic heat if the applied current density is large enough. In addition, the electrochemical reaction heat and activation heat have a lack of sensitivity to the porosity and flow rate, whereas an obvious increase of ohmic heat can be observed with the rise of the porosity. Lower porosity or faster flow shows better uniformity of temperature distribution. Thus, the model proposed in this paper shows good prospect in heat and temperature management for a VFB aiming at eliminating any crisis of internal heat accumulation. Keywords: Vanadium flow battery (VFB), Three-dimensional model, Thermal analysis, Heat generation, Temperature distribution