Development of air supplied ceiling radiant air conditioning system using the Coanda effect

Air-supplied ceiling radiant air conditioning is expected to become more popular in Japan in the future because there is no leakage from pipes and no condensation on the surfaces of radiant panels. Coanda air conditioning, a type of air-supplied ceiling radiant air conditioning, uses the Coanda effect, which is the tendency a fluid passing near a wall to maintain contact with it. As used commonly, Coanda air conditioning cools the ceiling surface by blowing airflow horizontally along it from the top of the wall surface and cooling by radiation1). In contrast, the line-type Coanda air-conditioning system proposed in this study (Figure 1) blows airflow to the ceiling in both directions from the air outlet, thereby enabling uniform cooling of the ceiling surface at low air volumes. As an initial study, this paper presents a case study involving the use of computational fluid dynamics to optimise the outlet shapes. The effectiveness of the proposed method is verified by using air diffusion performance index/predicted mean vote environmental assessment for a typical office space, and it is confirmed that the proposed method provides a comfortable thermal environment by radiant heat transfer mainly on the ceiling surface around the air outlet.