Power Transmission
Meeting emission standards
From 2013 and beyond, additional emission regulations will go into effect. Compliance with these standards presents an ongoing challenge to all manufacturers of diesel engines. Marc Ostermann reports.
N
ew and tougher emission standards have been put in place to combat the affects related to the release of noxious nitrogen oxide gas (NOx) into the atmosphere by diesel-powered vehicles including trucks, busses, construction and
agricultural equipment. With engine optimisation options fully developed and implemented, new requirements can only be met through effective methods for handling and treating exhaust gasses.
nitrogen oxides (NOx) in engine exhausts into harmless diatomic nitrogen gas and water. In a typical SCR system, a 32.5 per cent aqueous urea solution (ADBlue) is injected into the hot exhaust gas. ADBlue is hydrolysed above approximately 180°C forming ammonia, which in turn reacts with the gas to produce harmless nitrogen and water. ADBlue freezes at -12°C, therefore, conveying ADBlue
fluid throughout the SCR system requires high-quality hoses designed for SCR applications. There are three hoses which circulate ADBlue throughout the system (tank supply line, tank return line, pressure line). It is critical that the hoses are able to heat the Urea solution quickly, heat uniformly throughout the hose assembly including the fittings, and optimise power consumption in the system. Gates has therefore developed a design for SCR
assemblies, the EPDM-based hose construction has a special carbon fibre sleeve and come with heated fittings (SAE J2044 compliant quick connect couplings). Thermoplastic over-
Table 1. Implementation stages of EUR regulations.
In response, engine makers are utilising advanced technologies designed to meet the need and ensure compliance. The selective catalytic reduction system (SCR) has proved very successful in reducing emissions and thus has been accepted as the right answer versus other emissions technologies for the new EUR IV regulations that now start to come into place.
Selective catalytic reduction
A SCR system is comprised of a special catalytic chamber built into the exhaust system of a diesel engine. SCR uses a Diesel Exhaust Fluid (DEF) as a means of converting noxious
Table 2. Optimal performance. Metric
Heating Element Technology
Assembly Length Hose Tube Material Hose Inner Diameter Applied Current
Time to Thaw (-29°C to -10C)
Power Use 44
www.engineerlive.com Hose Design #1
Carbon Fiber Braided Sleeve
600 mm
Nylon (PA 12) 6 mm
2.5 amps 3 minutes Low
Fig. 1. This system sketch illustrates the different components in truck body.
Hose Design #2 Coiled Wire 600 mm
Nylon (PA 12) 6 mm
2.5 amps 8 minutes High Hose Design #3 Coiled Wire 645 mm
Nylon (PA 12) 6 mm
2.5 amps 6 minutes Medium
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