Determination of Air Change Rate in a room through CFD simulation in Ansys Fluent
 

Consider a room as depicted in the picture. The room has two supply diffusers at the ceiling and six floor level exhaust grilles (three exhausts are shown in the picture and other three exhausts are located on the opposite side). The room under study needs an air change rate of 3ACH. Based on the air change rate required, the mass flow rate through each supply diffuser is determined to be 0.62kg/s. The door (considered open) as well as the six floor level exhausts are given a pressure outlet condition of 0Pa. All the walls are adiabatic. The CFD simulations are carried out in Ansys Fluent under steady state condition. If in case, the pressure conditions at each floor level exhausts are altered to -1Pa (negative pressure), would it be right to say that the air change rate provided to the room is still 3ACH? Kindly provide your valuable comments.