Reducing Dust Deposition on Electronic Equipment

Chen Xu
Jason Stafford
Nokia Imperial College London

Environmental dust accumulation on electronic equipment can impact the performance and reliability of the equipment in various ways. This includes mechanical effects (such as obstructions of cooling air, moving parts and optical interference), chemical effects (such as corrosion and metallic dendrite growth) and electrical effects (such as impedance reduction, short and open circuits). Minimization of dust deposition on electronic equipment is necessary and beneficial to product performance and long-term reliability. This work focuses on one aspect of reducing dust accumulation on electronic equipment, specifically by optimizing the cooling air flow.

This work presents a detailed analysis on dust deposition mechanisms in air cooled electronic equipment using particle image velocimetry performed in situ on a cellular base station. Localized preferential dust deposition is driven by high velocity air flowing at an oblique angle at the exit of rotating axial fans. This oblique angle is a characteristic of all rotating axial fans, due to centrifugal forces in the exiting jet. This produces locally increased deposition velocities that is more than two orders of magnitude higher in zones where dust deposition was observed in the field. It was demonstrated that the addition of traditional filters on the fan inlet side may worsen the situation by enhancing the deposition mechanism through changes to the impingement angle. Finally, a method is proposed which uses aerodynamic guide vanes to control the flow locally, reducing the deposition mechanism while having negligible effect on the bulk fan performance. This work also highlighted the importance of maintaining low concentration of PM2.5 dust (most detrimental dust to electronic equipment) at the data center and the most practical and cost-effective way for removing PM2.5 is at the room level.