Field and laboratory plume dispersion studies of buoyant plume release in an urban environment

Stemming from the Western U.S. Energy Crisis in 2000 and 2001, movements towards power independence from the grid have risen for hotels, hospitals, restaurants, businesses and schools. One of the solutions is to install on site small scale power generators, known as distributed power generators (DGs). Although beneficial to local industries by providing power independence, questions have been raised towards the localized air quality and possible health impacts caused by these DGs. DG technology has led to the necessity for studies of elevated buoyant plume dispersions in urban environments.

Field and laboratory modeling of the DG exhaust plume dispersion was conducted for a site in Palm Springs, California. The selected 650 kW reciprocating gas engine generator located in the center of Sunrise Park was surrounded by a school, library, and residential housing. In the field, SF6 tracer gas was released with the exhaust of the facility and sampling sites were located in 100m, 400m, 1km, 2km and 4km arcs in the urbanized area. The laboratory modeling in a water channel was conducted at 1:100 scale. Planar Laser Induced Fluorescence (PLIF) and Particle Image Velocimetry (PIV) techniques were used to determine the concentrations and flow fields. The laboratory model was verified by field measurements. Next, parameters were systematically varied in the laboratory model to investigate the effects of exhaust plume buoyancy and the addition of simple geometric obstacle arrays upstream and downstream of the source on ground level concentrations. Special attention is given to a presence of a simple array of buildings downwind from the stack when lateral channeling within the array can lead to lower ground level concentrations. The new parameterization and results of the laboratory experiments will be presented.