Similar to supply air jets in mixing ventilation this paper describes a comprehensive flow model for displacement ventilation derived from the integrated Navier-Stokes differential equations for boundary layers. A new test method for low velocity diffusers in displacement ventilation is developed based on this new flow model. Contrary to jet flow, it is shown that the only independent variable in the new model is the buoyancy flux.

The influence of a cooled ceiling on the air quality in a displacement ventilated room is examined by means of CFD. The objective of the study is to examine how the flow field in a displacement ventilated room is influenced when a cooled ceiling removes a major part of the total heat load, and in particular to examine the effect on the contaminant distribution and the indoor air quality. The simulations show that the inclusion of a cooled ceiling has a significant impact on the flow field but only a minor influence on the personal exposure in this study.

The purpose of this paper is to evaluate the performance of 4 kinds of ventilation systems from the point of view of indoor air pollution and energy need during heating season under Japanese conditions by numerical simulation. TVOC was selected to characterize the indoor air quality impact to residents. The results show that in the case of mechanical exhaust ventilation system, TVOC level is the highest among all the systems. Mechanical central supply and exhaust ventilaton system shows its advantages for minimizing energy consumption and maintaining an acceptable indoor air quality.