Characterization of mixing patterns in a ventilated airspace with a multiple airflow regions gamma model

A model called the multiple airflow regions gamma model (MARGM) was develop ed based on a continuous distribution of residence time for predicting the mixing behavior in a ventilated airspace in that data interpretation and me an residence time calculation for a specified output concentration profile can also be evaluated. The MARGM takes the form of the two-parameter gamma distribution and accounts for different mixing types: complete mixing, no m ixing (piston flow), incomplete mixing, and various combinations of the abo ve types. In these combinations, the different mixing types simulated by th e MARGM conceptually represent airflow regions in series. The mixing effici ency was introduced to characterize the extent or degree of mixing in a ven tilation system. Mixing efficiency equals zero for piston flow (no mixing), unity for complete mixing, and a value in between these two extremes for i ncomplete mixing. The MARGM simulates the combinations of complete mixing, incomplete mixing, and piston flow. Therefore, seven models are introduced in this effort: complete mixing model, piston flow model, complete-piston f low model, complete-incomplete-piston flow model (the general model), compl ete-incomplete mixing model, incomplete-piston flow model, and incomplete m ixing model. The applicability of models was tested by several case studies . Results show that combination models give better fitting than other simpl er models. The MARGM enables building microenvironment designers reconsider the possibilities and consequences of various forms of incomplete mixing i n investigating indoor air quality problems.