CFD Study of Diffuse Ceiling Ventilation through Perforated Ceiling Panels

Abstract

Diffuse Ceiling Ventilation (DCV) is a promising concept to address internal air quality and thermal comfort requirements in contemporary buildings. Sound-absorbing perforated ceiling panels are common in office rooms and can be used as air diffusers without modifications. The optimization of such systems is not a trivial procedure, and numerical simulation can represent an important tool to carry out this task. Today, most of the numerical studies on DCV are performed using porous medium models and focus on the general system performance rather than on the optimization of the diffuser design. In previous studies, a CFD model was used to optimize the size and distribution of the ceiling perforation. In the study presented in this paper, the results of simulations conducted on a full-scale three-dimensional domain and the performance comparison between a continuous and non-continuous perforation distribution are given. The results show that the non-continuous diffuser design does not disturb the internal comfort and does not introduce a negative effect in the system performance. The different configurations lead to a different air distribution in the room, but in both cases, the velocity magnitude is always well below values leading to draft discomfort.

Numerical Investigation of Air Movement on Laboratory Scale Psychrometric Chamber

“…The calculation used an isothermal unsteady Reynolds-averaged Navier-Stokes with a SIMPLE pressure velocity couplings and a second order upwind spatial discretization. This method is preferred to ensure a stable numerical performance of the calculation [13]. The standard k-ɛ model is also used in this simulation due to its reasonable accuracy in simulating flow characteristics with applications ranging from industrial to environmental flows.…”

“…The air looped was supplied to ducting and distributed along with the clearance and the perforated ceiling. The perforated ceiling characteristic makes them suitable to act as a diffuser [13].…”

“…Furthermore, the large area of the air diffuser makes it possible to distribute the air ventilation compared to traditional mixing ventilation systems. Moreover, the diffuser has a lower pressure drop in the system, reducing air movement energy [13]. Despite several advantages in using perforated panels in the office or classroom, there is a need for the panel investigation on the psychrometric chamber application.…”

Numerical investigation of a diffuse ventilation ceiling system for buildings with natural and hybrid ventilation

“…In a previous work (Nocente et al 2018) three models (with different perforation size and distribution) of commercially available sound-absorbing panels were taken into account for the suspended ceiling. Two optimal combination were found in that study, and one of those was chosen to realise the numerical analysis presented in this work.…”

“…This first illustration previews how a direct inlet leads to potential discomfort (a) due to low air temperature (below 10 °C in most of the room) and an uneven distribution of the fresh air (b), especially if compared to a solution where the air is (much more evenly) distributed through the plenum of the dropped ceiling (c). The present investigation builds up on a previous work by the authors (Nocente et al 2018) in which CFD calculations were used to evaluate an optimal panel distribution for a typical office room which ensures a more even velocity distribution out of the perforated ceiling. The previous work focused only on the fluid-mechanical aspects, but neglected the thermal domain of the problem.…”