Air diffusion mode and energy conservation of HVAC systems in large space building

Energy consumption of HVAC (heating ventilation and air conditioning) system in large space building is normally higher than the energy consumption in small space building, and its indoor air flow field is also more complex than that in small space building. To study the air flow mode and the indoor air flow fields in large space is of great significance to the energy conservation of AC systems and thermal comfort of occupiers. In this paper, a large space building with stratified air conditioning system is chosen as a research object. Two air flow fields with different air diffusion modes are simulated by CFD software, one is mixing mode, in which all the conditioned air flow volume are discharged into the conditioned space through the linear slot diffusers mounted in the middle of north wall with the exhaust grilles being mounted in the lower part of south wall; the other is the horizontal displacement ventilation mode in which besides some of conditioned air flow volume is discharged into the conditioned space through the linear slot diffusers, the remainder is sent into the conditioned space from the perforated sidewall diffusers with the decayed air being exhausted from the opposite wall. By comparing and analyzing two simulated air flow fields, the better one is obtained, which is the latter. It is better on energy conservation and contaminant emanation in large space building.