A novel personal comfort system for older adults in hot conditions: Design, modelling, and performance

This study introduces a novel personal comfort system aimed at establishing a relatively uniform thermal microclimate around the body to meet the thermal needs of seated elderly individuals under hot conditions. The system integrates cool air supply vents into a chair to provide thermal comfort by i) generating upward airflow by colliding jets to disperse cool air across the upper body; and ii) releasing air flow targeting the lower body by relying on buoyancy for air confinement. A computational fluid dynamic model was developed to predict the flow and thermal fields around the occupant who is seated on a chair equipped with the proposed system. The model was experimentally validated in a climatic chamber using a thermal manikin. An elderly bioheat and thermal sensation models were used to predict skin temperatures and corresponding sensation of elderly users. The microclimate was assessed in terms of effective confinement of cool air around users and improvement in elderly thermal sensation. At a total chair supply flow of 17 l/s, microclimate air confinement was attained. At 29 degrees C room temperature, the proposed system lowered the mean skin temperature from 34.15 degrees C to 33.33 degrees C and improved the whole-body TS, which decreased from slightly warm to neutral. At 33 degrees C room temperature, the mean skin temperature decreased from 35.6 degrees C to 33.99 degrees C and the sensation improved, decreasing from above warm to below slightly warm.