An Air Distribution Index for Assessing the Thermal Comfort and Air Quality in Uniform and Nonuniform Thermal Environments

Abstract

This study introduces a new Air Distribution Index (ADI)_New to assess the ventilation performance in uniform and nonuniform thermal environments. The index comprises parameters for assessing the indoor thermal comfort and air quality in occupied spaces. The thermal comfort assessment was carried out using a virtual thermal manikin that is adjusted by a model of human thermoregulation and coupled with a psychological comfort model. The virtual manikin was used in a computational fluid dynamics (CFD) code to simulate tests in an environmental chamber that were largely conducted under thermally neutral conditions with mixing ventilation (MV) or displacement ventilation (DV) systems. Eight human subjects were used in the study that included measurement of their skin temperature, local and overall thermal sensation votes during their exposure to the MV and DV systems. The results from CFD predictions were compared with measurements in the test chamber. The predicted (ADI)_New parameters, such as the thermal comfort, the ventilation effectiveness for both heat and contaminant removals as well as the local mean age of air, were compared with measured values in the chamber and found to be in good agreement. The results demonstrate that (ADI)_New is a useful index for evaluating the performance of a ventilation system under uniform thermal environment and can also be applied to nonuniform environment.