Determination of the geometric shape of the air collector for supplying thermal energy to the heating system of electric bus batteries

Abstract

Operation of electric buses in the winter climatic conditions of Russia is associated with the need to maintain positive temperatures of battery cells of the traction battery, taking into account the maximum available energy at battery temperature plus 20 ... 25 ° C. When operating battery cells that have negative temperatures, the energy of the batteries decreases by 20 ... 25%. The average temperature in the central part of Russia ranges from minus 18 ° C to plus 25 ° C. To ensure the battery operation in the above-mentioned temperature ranges, a thermostating system is installed. Depending on the operating conditions, these systems are performed both liquid and air. For air heating and cooling of the battery, a self-contained air heater is used as a heat source: a generator of heated air gases, and for cooling - supply and exhaust fans. Heated air passes through the collector from the auxiliary heater to the inlet ventilation holes. The geometric shape of the collector affects the flow rates of the air streams blown from the four outlets. Uneven consumption causes improper heating of the battery, which in turn leads to a charge imbalance between the individual battery packs and a decrease in battery capacity. The objective of the study is to determine the geometric shape of the air manifold, which provides equal heat flow through the outlet openings. The solution of this problem was performed by iterative calculations of air flows in various geometric forms of the collector in ANSYS CFX software. The results of calculation of air collectors intended for heating and ventilation of electric bus power batteries are presented in the article. The optimal shape, which ensures an equal flow of heat energy through the outlet holes, is determined.