When a proton exchange membrane fuel cell is operated in a dead-ended anode mode, nitrogen and water will diffuse from the cathode to the anode and accumulate in the anode channel. Accumulated nitrogen and water cause hydrogen depletion in the channel and reduce the performance of the fuel cell. This performance drop can be recovered by opening the purge valve at the anode outlet. However, unused hydrogen is purged out of the anode with nitrogen and water, causing the decrease of energy efficiency. To study the effect of the purge strategy on energy efficiency, a mathematical model capable of capturing the variation of the gas composition along the anode channel is developed. The effects of operating current density and purge strategy on the time evolutions of local current density and gas composition are presented. The optimum energy efficiency with respect to the purge duration of the purge valve is also discussed. (C) 2016 Elsevier Ltd. All rights reserved.