A NEW GAS INJECTION METHOD TO ENHANCE SPATIAL UTILIZATION WITHIN A FREE-AIR CO2 ENRICHMENT (FACE) SYSTEM

Visual observations of smoke dispersion in a wind tunnel and a computa tional fluid dynamics (CFD) model were used to evaluate methods of imp roving the performance of Free-Air CO2 Enrichment (FACE) Systems for f ield studies of the effects of elevated CO2 on vegetation. A special b affle, named an Enhanced Local Mixing (ELM) system, was observed to in crease the turbulence and consequent dilution of fumigant gas in the a tmosphere. Modelling results suggest that the ELM design reduces the s patial variation of fumigant gas concentration in small experimental p lots. The potential reduction in CO2 use and costs warrants further ev aluation under field conditions.