Comparative study of the performance of displacement vs conventional ventilation using CFD

The purpose of this paper is to compare the performance of displacement and mixing ventilation techniques focusing mainly on temperature and velocity distributions for a site in South Africa. These metrics are central to the performance of ventilation systems. The comparison is based on experimentally obtained data validating a computational fluid dynamics (CFD) model. CFD simulations are becoming a key tool in investigating performance of heating, ventilation and air conditioning (HVAC) systems. Experimental measurements are conducted in a specially designed test chamber incorporating under floor air distribution supplied from a split HVAC system. Focusing on energy efficiency and thermal comfort, the results of the investigation reveal that displacement ventilation has superior performance over conventional ventilation for the cooling period. Despite these benefits, adoption of this technology has been slow, especially in the South African market. This prompted one of the local engineering consulting companies to initiate this research work with a view to develop local knowledge on the benefits of adopting this technology given the power deficit that the country is currently facing. Displacement ventilation therefore continues to prove that it has demonstrable potential in reducing power consumption while achieving the same, and in some cases better, indoor air quality and thermal comfort.