2.2.2. Exhaust air region
The scale for ventilation efficiency 5 (SVE5) was calculated for exhaust openings and . The SVE5 is an index showing the portion of air which is vented from a given opening when several exhaust openings are present [8]. The SVE5 is defined by Eq. (1) below.
equation(1)
where n is the number of exhaust openings, C(x,n) the concentration at a point x obtained by solving the concentration transport equation in the reverse direction of time. Initially the room is clean and the concentration at the nth exhaust opening is C0(n).
Let us take a look at SVE5 contours for exhaust opening in Fig. 3. As the exhaust amount increases, regions with a higher SVE5 value increase rapidly. When the exhaust amount becomes one half of the total amount, most of the area reaches more than 0.9, in other words, nearly all of the air in this area is vented from opening . The SVE5 contours of exhaust opening are complementary to those of opening . Since there are only two exhaust openings, the sum of the SVE5 values for openings and should be exactly 1.0, although the numeric results are only approximately 1.0.