Ventilation Performances of Mixing, Displacement, and Impinging Jet System under Different HVAC Scenarios : Part II

In most conditioned spaces, the Mixing Jet Ventilation (MJV) systems are commonly installed. Relying on turbulent mixing, MJV homogeneously controls the room environment. However, Indoor Air Quality (IAQ), draft, and noise can sometimes be drawbacks of MJV systems. In late the 70s, Displacement Ventilation (DV) was first introduced. By supplying low supply velocity air from the floor or lower wall, a stratification zone is formed which forces pollutants to be collected near the ceiling and allows clean air to remain in the breathing zone. To avoid discomfort associated with stratification, a warm supply temperature is suggested. Accordingly, the dehumidification and reheat energy become obstacles. Recently, a new concept, Impinging Jet Ventilation (IJV), has been introduced. By placing the supply terminal toward the floor within the impinging range, IJV successfully utilizes the advantages of MJV and DV. A supply temperature of 55F can be commonly applied. Previous studies show that IJV is particularly appropriate for space with fixed seating arrangements. Since IJV is new, this research aims quantify IJV ventilation performances including energy conservation, stratification discomfort, draft, IAQ, and relative humidity under both cooling and heating conditions. Using Computational Fluid Dynamics (CFD) as a primary research tool, 96 different scenarios were simulated. Under appropriate supply velocity and temperature, IJV reduces energy consumption and improves a rooms IAQ.