PEM fuel cell-assisted lithium ion battery electric vehicle integrated with an air-based thermal management system

Abstract

A novel integration of a proton exchange membrane (PEM) fuel cell with lithium ion batteries is presented for a hydrogen electric vehicle. The performance of the PEM fuel cell is affected by the temperature of input air that is drawn from the environment for electrochemical reaction with the hydrogen. Preheating the input air before it enters the PEM fuel cell can potentially improve its performance, especially during cold weather conditions. In addition, removing the heat generated in the lithium ion battery cells is necessary for efficient, safe and long-term operation of the hydrogen electric vehicle. In this context, this study introduces an air-cooled battery thermal management system in which the air is taken from the environment, preheated through cooling of batteries and then used in the PEM fuel cell stack. Both the PEM fuel cell and the lithium ion battery systems are analyzed to investigate the compatibility and applicability of the proposed system. Also, the PEM fuel cell electrical power output and energy efficiency are assessed through varying the operating conditions. It is found that, at a current density of 0.4 A/cm2, the energy efficiency of the PEM fuel cell improves from 45% to 48% by preheating the air from 10 °C to 40 °C. Furthermore, during discharge of the lithium ion battery, the cooling air removes an average heat generation rate of 3.5 W per unit area of the lithium ion battery to maintain the battery temperature at around 25 °C.