Frontal Suction Methods

Ref-Nr: TDO0218

Technology abstract

The basic problem in removing gases or gaseous pollution by suction is the weak suction velocity in free space. This velocity decreases rapidly with the distance to the suction mound or filter area. By creating a frontal vortex, a frontal flow field is induced that blocks and reverses thermal flows. This method increases the efficiency of suction devices that are used, for instance, in kitchen or laboratory environments to remove gases or gaseous pollution by suction.

Technology Description

The basic problem in removing gases or gaseous pollution by suction is the weak suction velocity in free space. This velocity decreases proportional 1/r², where r is the distance from the suction mound or filter area. Pollutants that are lighter or heavier than the surrounding atmosphere gather under or on top of surfaces (so-called 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 (first image).
Conventional technologies use high suction rates to increase the suction flow towards the suction opening or filter areas. However, for many purposes, such as the removal of polluted flows, pure suction is too weak to gather and exhaust accelerated flows dynamically. To increase the range of the suction flow field, additional jets, so-called air-curtains, could be applied. Unfortunately, the air curtain method is not appropriate for fast flows, vapours and strongly heated gas. Such flows are common in most production processes and also in kitchens.
Frontal Suction Methods create flows that block and reverse escaping flows near surfaces. For this purpose, a vortex flow or a circular shear flow is created near to a wall (first image). This creates a “dynamical frontal” flow that reaches also into the free space (second image). Polluted gas flows - especially of high velocity - are stopped and transported towards the suction openings.
Frontal flows are generated with specially patented nozzles, so-called Frontal Vortex Generators (FVG), which, depending on their design, produce a frontal flow of either Jet-vortex type or Coanda-vortex type.

Innovations & Advantages

  • better suction efficiency
  • less suction volume flow
  • reduced energy costs
  • allows for smaller suction pipe diameters
  • allows for noise reduction
  • offers possibilities to develop new suction devices and gadgets

Further Information

Current and Potential Domains of Application

  • kitchen techniques (use case for current developments)
  • laboratory techniques, fume hood
  • production techniques - soldering or welding working places
  • air curtain doors
  • colour spray techniques