Modeling the Performance of Personalized Ventilation under Different Conditions of Room Air and Personalized Air

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Abstract
Building-related health complaints and sick building syndrome (SBS) represent significant health problems. Personalized ventilation (PV) is able to provide better inhaled air quality since the fresh air is supplied directly to the breathing zone “gently.” In this paper, after the numerical methods are validated by experiments, a seated computational thermal manikin (CTM) with geometry of a real human body is used to carry out the parameters study of PV. The modeling outcome shows that in a stagnant environment the human body is enclosed by the thermal plume, whose intensity is affected by the room air temperature. Warm rising airflow around the human body will entrain room air into inhalation and thus decreases the fraction of personalized air in the inhaled air. A uniform invading airflow in the horizontal level with the speed of 0.2 m/s (40 ft/min) is strong enough to tear away the thermal plume at the windward side of the human body. Its effect on the performance of PV is dependent on the flow direction. The benefits of personalized air supplied at a low rate limited by draught criteria are very sensitive to the ambient air conditions, which are, in turn, controlled by the background air-conditioning system.