| Abstract | The ventilation performance of cold-air distribution systems was investigated in a full-scale test room for three different designs of ceiling-mounted diffusers: a large square radial, a small square radial, and two linear diffusers. The supply air temperature was 38 F (3.3. C). Tests were conducted with internal heat loads and with and without furnishings. The local mean ages of air,Air diffusion effectiveness and contaminant-removal efficiency were measured using tracer gas techniques to assess the performance of the ventilation system in maintaining adequate air quality conditions in the occupied region. Air velocities and temperatures were also measured in the occupied region to calculate the air diffusion performance index (ADPI). It was found that the cold-air distribution system provided satisfactory air quality and thermal comfort conditions to the occupied region of the room. It was also found that internal furnishings (partitions, tables, etc.) had no appreciable effect on the local mean ages of air, but they reduced the system's ability to remove the air contaminant compared to the empty room situation. Additionally, tests were also conducted for selected diffuser designs under a supply air temperature of 55 F (12.8 C), which is commonly used in conventional air distribution systems. No appreciable differences were found between the cold and conventional air distribution systems for the tested diffuser designs and test conditions in terms of air quality and thermal comfort conditions in the occupied region. |
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