Accidental leakage of hydrogen in residential fuel cell systems can be dangerous because hydrogen has a high risk of inflammation or explosion when stagnant in a space Thus, ventilation of residential fuel cell systems should be properly designed to reduce the hydrogen stagnation inside the system enclosure and thus to enhance the safety In this study, computational fluid dynamics (CFD) simulations were conducted to predict the hydrogen dispersion and exhaust behaviors in residential fuel cell systems equipped with a forced ventilation device A realistic three-dimensional geometric model for the system enclosure was constructed based on the actual dimension and appearance of a commercial residential fuel cell system The flow pattern and hydrogen concentration in residential fuel cell systems were investigated by varying the an intake position and the air intake area in CFD simulations (C) 2009 Elsevier B V All rights reserved