1 variants of dpfs
1.1 cordierite wall flow filters
1.2 silicon carbide wall flow filters
1.3 ceramic fiber filters
1.4 metal fiber flow-through filters
1.5 paper
1.6 partial filters
variants of dpfs
cordierite diesel particulate filter on gm 7.8 isuzu
unlike catalytic converter flow-through device, dpf retains bigger exhaust gas particles forcing gas flow through filter; however, dpf not retain small particles , maintenance-free dpfs break larger particles smaller ones. there variety of diesel particulate filter technologies on market. each designed around similar requirements:
cordierite wall flow filters
the common filter made of cordierite (a ceramic material used catalytic converter supports (cores)). cordierite filters provide excellent filtration efficiency, relatively inexpensive, , have thermal properties make packaging them installation in vehicle simple. major drawback cordierite has relatively low melting point (about 1200 °c) , cordierite substrates have been known melt during filter regeneration. issue if filter has become loaded more heavily usual, , more of issue passive systems active systems, unless there system break down.
cordierite filter cores catalytic converter cores have had alternate channels plugged - plugs force exhaust gas flow through wall , particulate collects on inlet face.
silicon carbide wall flow filters
the second popular filter material silicon carbide, or sic. has higher (2700 °c) melting point cordierite, not stable thermally, making packaging issue. small sic cores made of single pieces, while larger cores made in segments, separated special cement heat expansion of core taken cement, , not package. sic cores more expensive cordierite cores, manufactured in similar sizes, , 1 can used replace other. silicon carbide filter cores catalytic converter cores have had alternate channels plugged - again plugs force exhaust gas flow through wall , particulate collects on inlet face.
the characteristics of wall flow diesel particulate filter substrate follows: broad band filtration (the diameters of filtered particles 0.2-150 μm); high filtration efficiency (can 95%); high refractory; high mechanical properties. high boiling point.
ceramic fiber filters
fibrous ceramic filters made several different types of ceramic fibers mixed form porous media. media can formed shape , can customized suit various applications. porosity can controlled in order produce high flow, lower efficiency or high efficiency lower volume filtration. fibrous filters have advantage on wall flow design of producing lower pressure. ceramic wall-flow filters remove carbon particulates completely, including fine particulates less 100 nanometers (nm) diameter efficiency of greater 95% in mass , greater 99% in number of particles on wide range of engine operating conditions. since continuous flow of soot filter block it, necessary regenerate filtration properties of filter burning-off collected particulate on regular basis. soot particulates burn-off forms water , co2 in small quantity amounting less 0.05% of co2 emitted engine.
metal fiber flow-through filters
some cores made metal fibers - fibers woven monolith. such cores have advantage electrical current can passed through monolith heat core regeneration purposes, allowing filter regenerate @ low exhaust temperatures and/or low exhaust flow rates. metal fiber cores tend more expensive cordierite or silicon carbide cores, , not interchangeable them because of electrical requirement.
paper
disposable paper cores used in specialty applications, without regeneration strategy. coal mines common users — exhaust gas first passed through water trap cool it, , through filter. paper filters used when diesel machine must used indoors short periods of time, such on forklift being used install equipment inside store.
partial filters
there variety of devices produce on 50% particulate matter filtration, less 85%. partial filters come in variety of materials. commonality between them produce more pressure catalytic converter, , less diesel particulate filter. partial filter technology popular retrofit.
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