Frontal Suction Methods
The basic problem to remove gases or gaseous pollution by suction is the weak suction velocity in the free space. This velocity decreases proportional 1/r² . Where r is the distance from the suction mound or filter area.
Pollutants lighter/heavier than the surrounding atmosphere gather under/on surfaces (density currents). For example water vapour ascends as a thermal jet. When this jet hits a horizontal surface it spreads under this plane as a density current. The typical example is the flow under a cooker hood.
Conventional technologies use high suction rates (= higher suction flow) or sometimes additional jets (air-curtains) to increase the suction flow towards the suction opening or filter areas.
The frontal suction methods create flows that block and reverse escaping flows near surfaces. A vortex flow or a circular shear flow is created near to a wall. This creates a “dynamical frontal” flow that reaches also into the free space. Polluted gas flows - especially of high velocity - are stopped and transported towards the suction openings. There are three methods to create and to adjust frontal flows.
Innovations & Advantages
- better suction efficiency
- less suction volume flow
- this creates a) less energy costs b) smaller suction pipe diameters
- noise reduction
- possibilities to develop new suction devices and gadgets
Current and Potential Domains of Application
Application Fields are:
- kitchen techniques (origin of developments)
- laboratory techniques, fume hood
- production techniques - soldering or welding working places
- air curtain doors
- colour spray techniques.