Stratified micro-environments using a sidewall air supply: An experimental and simulation study

The idea of providing stratified micro-environments in a shared environment by utilizing a sidewall air supply is proposed, to provide different thermal comfort and air quality levels to satisfy individual needs at different occupied positions. Experimental cases with various supply air parameters and room layouts are conducted in a mock consultation room consisting of two face-to-face occupants. Further, parametric studies using computational fluid dynamics (CFD) are performed. Overall thermal sensation and local thermal comfort are both evaluated. Tracer gas (i.e., CO2) concentration distributions are investigated experimentally, while the air age is used as an indicator in CFD simulations. The results show that the proposed strategy simultaneously provides displacement ventilation (DV) and stratum ventilation (SV) in a shared environment, satisfying individual preferences and needs. The demarcation thermal length of the supply air jet between DV and SV is around 0.8 m. The normalized contaminant concentration at the breathing level is 0.00–0.30 with both table and floor contaminant sources. Better air quality is achieved in the area served by a higher thermal length. The local discomfort and “lock-up” effect under DV is reduced, by the interaction between the supply air jets, which is validated, as the partition impeding the interaction brings a significant influence. Short jet spacing of 0.75 m implies that multiple stratified micro-environments can be provided in a medium room, while a medium distance between the occupant and the supply air terminal (i.e., 1.7 m) is the most efficient in cooling and renewing the air age. •Airflow patterns of stratum ventilation and displacement ventilation co-exist, with a demarcation thermal length of 0.8 m.•The interaction between the supply air jets improves local comfort and air quality.•The air quality is satisfactory with two pollution sources; a higher thermal length provides a better air quality.•The influence brought by jet spacing (0.75–1.5 m) is minor.•The most efficient distance between supply air terminal and the occupant is 1.7 m.