Flow

Besides electric field and current density distribution, gas flow is important in ESP performance. ESP flow velocities vary between 0.2 and 2.0 ms-1. Schwab and Johnson suggest an optimum velocity of between

1.22 and 1.52 ms"1. Lower velocities diminish the turbulent mixing which brings small particles into the low flow region near the collector electrode; higher velocities overwhelm electrostatic attraction of particles to the collector electrode, and can lead to re-entrainment.

Flow within an ESP is inherently turbulent due to high gas flow velocity, which typically results in a Reynolds number of about 10 000 - five times that at which turbulent flow replaces laminar flow. Turbulence in ESPs is complicated by flow obstructions - discharge electrodes and collector stiffening baffles and connectors, and by a non-uniform flow profile at the ESP inlet. At low velocities (<0.5 ms"1) turbulence resulting from the ion current between discharge and collector electrodes (ionic wind) contributes significantly. The flow regime in an ESP is thus seen to be quite complicated. Baffles within the ESP duct and porous plates at the inlet and outlet are employed to create uniform flow.

Schwab and Johnson have produced a computer model based on Navier-Stokes fluid flow equations as an alternative to traditional reduced scale physical models for flow design. The model can be used to determine inlet plate perforation patterns which produce uniform flow without high flow near the duct walls.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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