Characterization of the field and laboratory emission cell - FLEC: flow field and air velocities

The Field and Laboratory Emission (FLEC) has been designed for VOC emission testing of material surfaces. Knowledge about the air flow field in the cell compartment is highly desired, as the air velocity at the sample surface may considerably influence the emission behaviour. A simple mathematical approach of flow theory predicted an unevenly distributed air flow into the FLEC. This could be confirmed by air velocity measurements using a self-constructed hot-wire anemometer. With a total flow of 250 ml min -1, air velocities measured at the surface ranged from <0.1 to 0.9 cms-1. A surface area of very low air velocities was detected in the FLEC centre with a radius of ~ 20 mm. A VOC emission test using a simulated punctual source yielded different emission rates at different locations in the cell compartment.