Effects of harmattan dust on vehicle air filters
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Date
2012
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Abstract
Most parts of West Africa experience abnormally high levels of atmospheric dust suspension and deposition from November to March as a result of the dust-laden North-East Trade Winds which blow over the region from the Sahara Desert. This seasonal phenomenon is known as the Harmattan. The Harmattan dust aerosols have different particle characteristics and come in concentrations that are about two to three orders of magnitude higher than the non-Harmattan dust. The performance of engineering devices, systems and equipment therefore needs to be studied during the Harmattan period and the necessary redesign or improvements made.
The behaviour of air filters utilized for removal of dust particles from air during the Harmattan period and the effects they have on the performance of engines in vehicles has been extensively studied. Different aspects of the study were considered including processes of removal of dust particles by filters and the efficiency of the filters in relation to engine performance. Three filters (two paper filters and one foam filter) of different but comparative parameters were used for the study. Inflated dust from untarred road was collected by plastic sheeting materials. Settling Harmattan dust was also collected from the roof top of the College of Engineering new 4-storey classroom and laboratory block.
The results of the investigation showed that when the Harmattan season sets in, the pressure drop across filters increase significantly and causes clogging of the filters within a short period (2 to 3 times faster). Air filters in vehicles that ply on untarred roads exhibit higher pressure drops than those used in vehicles on tarred roads. Further steps towards design of these air filters are also discussed.
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A thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirement for the award of the degree of Master of Science in Mechanical Engineering,