Studying comfort in a room with cold air system using computational fluid dynamics

Abstract

Cold air system has proven to offer economic and environmental benefits. However, these systems did not spread because of the fear from cold draft formation leading to unaccepted indoor conditions. In this paper, Computational Fluid Dynamics (CFD) was used to evaluate the performance of cold air system inside a 2D space. The flow of cold air was studied at different supply temperatures, velocities, and room thermal loads. The velocity field and the temperature distribution were used to calculate the effective draft temperature. And hence, the comfort level was assessed using the Air Diffusion Performance Index, ADPI. The effect of each factor was studied independently at different loads. It was shown that reduction in supply temperature and velocity each causes limited enhancement on the ADPI. The main source of drafts was the heat flux from the floor. The velocities induced by the floor heat flux were sometimes higher than the jet velocity. Keywords: Cold air system, CFD, Comfort, ADPI