Since the application of wind guide and flow circulators makes the flow inside the energy storage system complicated and difficult to predict, research to numerically predict the flow and heat transfer characteristics inside the energy storage system is important. In this study, the cooling performance according to the heat pump discharge angle and wind guide angle was numerically investigated. Three cases were considered to evaluate the cooling performance of the wind guide and flow circulator. The angle of the wind guide and the discharge angle of the heat pump are 5° and 45° in Case 1 and 15° and 30° in Case 2, respectively. Case 3 is a structure in which a flow circulator is applied. In this regard, three-dimensional and computational fluid dynamics simulations have been conducted. As a result, the maximum and average temperatures of the battery rack can be reduced by 11.9 % and 11.17 %, respectively. The cooling performance according to the cooling conditions of the energy storage system was analyzed by analyzing the maximum, average, and minimum temperatures of the battery rack according to the change in the flow rate of the heat pump and the flow circulator.