Experimental investigation on airflow pattern for active chilled beam system

Abstract

Experimental results of the airflow pattern for Active Chilled Beams (ACB) system are investigated in this paper, where the air velocity and turbulence intensity for the air jet near the ceiling are tested and recorded under both isothermal and non-isothermal conditions. Based on the results, the velocity profile along streamwise direction is found to be significant in analyzing air detachment from the ceiling. It is revealed that the Coandă effect can be enhanced by a high pressure drop of ACB terminal unit and impeded by the temperature difference between supply air and room air. The self-similarity for the air jet is observed to be feasible for a certain downstream distance where the vertical maximum velocity is within 1.25 slot heights. A comparison study has been conducted for two mathematical models describing the self-similarity with the experimental data. It turns out that Verhoff's model has an overall better performance than Schwarz and Cosart's model. The turbulence intensity, which tends to be larger for points with lower velocity, is higher in areas where the entrainment effect is stronger.