Emission control, vehicle heavy-duty vehicles

Emission control from heavy duty diesel engines in vehicles and stationary sources involves the use of ammonium to selectively reduce N O, from the exhaust gas. This NO removal system is called selective catalytic reduction by ammonium (NH3-SGR) and it is additionally used for the catalytic oxidation of GO and HGs.The ammonia primarily reacts in the SGR catalytic converter with NO2 to form nitrogen and water. Excess ammonia is converted to nitrogen and water on reaction with residual oxygen. As ammonia is a toxic substance, the actual reducing agent used in motor vehicle applications is urea. Urea is manufactured commercially and is both ground water compatible and chemically stable under ambient conditions [46]. 

The type approval of the engine rather than the complete vehicle introduces difficulties for current and future heavy-duty vehicles, as they are equipped with advanced after-treatment systems. In such cases the complete engine, after-treatment system and electronic control system have to be set-up in the laboratory for type approval to take place. To avoid this complication, type approval of the complete vehicle at the Euro VI level can be performed on the road using portable emission measurement systems (PEMS). Regulation 582/2011 specifies the technical details of the measurement. 

The technology for controlling emissions from heavy-duty vehicles has, until recently, focussed on in-cylinder measures such as direct injection (DI) and high-pressure injection (HPI, >150 MPa). However, at current and future emission levels SCR has become the NOx emission-control technology of choice, whilst DPFs will effectively become mandatory at the Euro VI level (Table 4). 

Biswas S, Verma V, Schauer JJ, Cassee F, Cho AK, Sioutas C (2009) Oxidative potential of semi-volatile and non volatile particulate matter (PM) from heavy-duty vehicles retrofitted with emission control technologies. Environ Sci Technol 43 3905-3912... 

Maly, R.R., Effects of GTL diesel fuels on emissions and engine performances . Paper presented at the 2004 diesel engine emission reduction conference, 29 August - 2 September, 2004, Coronado, California May, M., Development and demonstration of Fischer-Tropsch fueled heavy-duty vehicles with control technologies for reduced diesel exhaust emission . Paper presented at the 2003 diesel engine emission reduction conference, 24-28 August, 2003, Newport, Rhode Island... 

Equivalent reductions in permitted emissions have now been translated into proposed standards for Light Commercial Vehicles and later this year proposals will be made for Heavy Duty Vehicles. European regulations would then become equivalent in the level of emission control to those in the LFSA, including California, reflecting increasing concerns in Europe on the health and environmental effects of pollution from transport. 

In the US, heavy-duty vehicles are defined as vehicles with gross weight over 8,500 lbs. USEPA emission standards for heavy duty diesel truck and bus engines controlled particle mass emissions from 0.60 g bhp h in 1990 to 0.10 g bhp h in 1998. A new stringent mass emission standard that took effect with the 2007 heavy-duty engine model year limits particle mass emissions to 0.01 g bhp h . This included a diesel fuel regulation that currently limits sulphur content to 15 ppm. 

EPA. 1980a. Control of air pollution from new motor vehicles and motor vehicle engines gaseous emission regulations for 1984 and later model year heavy-duty engines. Environmental Protection Agency. Federal Register 45 4136-4149. 

Exhaust gas catalysts has been widely used since the laimching of the 1970 Clean Air Act in the USA and especially after the introduction of stricter regulations in 1981. At present, one of the fastest growing areas of catalyst-based technology is automotive pollution control. All gasoline-fuelled vehicles sold in the USA, Japan and in the European Community must be equipped with exhaust aftertreatment in order to meet the emission standards. Oxidation catalysts for heavy-duty vehicles have only been used for a short period, but following the tightening emission standards there will be an increased demand for such systems. 

Proposed legislation controlling exhaust emissions from heavy duty diesel vehicles will require significant reductions in the levels of harmful gases and particulates escaping to the environment. The allowed limits will decrease in some cases by an order of magnitude over the next five to eight years. A number of different... 

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