The global trucking industry produces 1.6 billion metric tons of CO2 per year making it responsible for 5.75 percent of total greenhouse gas emissions. Fuel remains the largest cost of operating a truck, costing more to a company than the driver. Heavy-duty tractor-trailers in the United States alone consumed approximately 26 billion gallons of fuel in 2016.
With trucking predicted to grow by 2 percent or more each year, improving the fuel efficiency of this industry is critical to reducing greenhouse gas emissions and supporting profit margins in an increasingly regulated industry.
To reduce exhaust emissions, auxiliary exhaust after treatment systems are used for diesel engines. Diesel Oxidation Catalysts (DOC) and Diesel Particulate Filters (DPF) have been mandated in order to comply with current regulations.
With the help of a DOC, HC and CO are oxidized at an adequate exhaust temperature to become CO2 and water. To do this, the rare metals platinum and palladium are applied to the catalyst support on a surface-enlarging wash coat.
An oxidation of the soot particles is not possible in the DOC. Nevertheless, the DOC has important functions in conjunction with the exhaust after treatment of particulate emissions: Hydrocarbons (SOF) adhering to soot can be oxidized or cracked, thus reducing the particulate mass to a significant extent. The DOC can also be used as a catalytic burner that increases the exhaust temperature for active soot filter regeneration.
The DPF filter is designed as a honeycomb structure with alternately closed ports. Since almost all emitted particles are smaller than the pores of the filter substrate, they are not caught in the filter due to their size but mostly by means of diffusion. Since the diffusion speed increases with decreasing particle size, smaller particles are actually separated the most effectively. With rising soot loads, there is a transition from deep filtration in the filter wall down to surface filtration.
The DPF affects diesel engine performance in two ways.
[1] Engine efficiency decreases with increasing backpressure due to thermodynamic reasons. The pressure drop of the DPF increases as it captures particulate matter from the engine. Large backpressure not only reduces efficiency, but could also damage the engine.
[2] The DPF must be regenerated, continuously or intermittently. Continuous regeneration only occurs when the exhaust gas temperature is higher than the soot-balancing temperature (SBT) for a significant fraction of time. This often requires high loading of PGM catalyst in the DPF washcoat. For most DPFs that typically operate below the SBT, active regeneration is required when the pressure drop exceeds a threshold. To enable an active regeneration event, the exhaust gas temperature must be raised to well above the SBT using extra heat generated either by the engine or by an auxiliary heat source. This, of course, consumes energy. Therefore, DPF regeneration, active or passive, intermittent or continuous, comes with a fuel penalty.
This fuel penalty can be reduced through installation of the WorldKlass Technologies IR system. In achieving a more complete combustion, less carbon and thus particulate matter enter the exhaust stream. Citing a NYC Department of Sanitation report dated September 30, 2016 (25DN-072 test project report), 45% reduction in particulate matter was noted.
This is significant in that WK reduces the amount of backpressure due to less soot particles accumulating in the DPF, thereby eliminating the need for the system to regen.
