Compliance with increasingly strict exhaust emissions standards is one of the biggest challenges facing diesel engine manufacturers.
In 2011 the Tier 4i regulations will go into effect in the US, and in Europe the fourth level of emissions legislation will take hold in 2013 - and in the meantime, an increasing environmental and climate awareness is becoming obvious in various regulations in Asia.
The resulting requirements can be satisfied only with an effective gas after-treatment, because the necessary exhaust values can no longer be achieve by optimisations to the engine.
A very promising alternative is the selective catalytic reduction technology, which transforms noxious nitrogen oxide (Nox) into steam and nitrogen with the help of a carbamide solution (AdBlue).
EPDM
With a heatable EPDM-based hose line, which was developed especially for the SCR process, ContiTech is a pioneer in the introduction of this future-orientated technology.
Selective catalytic reduction (SCR) technology long ago established itself in commercial road vehicles, which must already comply with strict limit values in Europe and the US.
In the final analysis, the new technology makes it possible to reduce nitrogen oxide and hydrocarbon emissions by up to 80 per cent.
Soot particulate emissions can also be cut by as much as 40 per cent, making it possible to cut nitrogen oxide emissions to less than 3.5 g/kWh.
In the meantime, engine manufacturers such as Deutz and MTU make use of the technology as well, and manufacturers of farm implements such as ACGO-Fendt also rely on the eco-friendly process as does the construction machinery manufacturer Liebherr.
Heating filaments
For instance, engine manufacturer Deutz is now offering a modular system for its compact engines that reduces noise and pollutant emissions - the DVERT, for example, Deutz Variable Emission Reduction Technology.
The components ensure optimal performance and efficiency as well as compliance with specified emission thresholds.
In order to reduce nitrogen oxide emissions, it also utilises the SCR process and the lines developed especially for the technology by ContiTech Fluid Technology.
The hose line module transports the AdBlue carbamide solution needed to convert the pollutants into harmless nitrogen and water vapour and prevents it from freezing.
To convert nitrogen oxide, the AdBlue liquid carbamide solution carried in a separate tank is metered into the catalyst's injection system via a media-resistant hose line.
The problem here is that carbamide freezes at about -11°C, depending on the concentration.
The special feature of the ContiTech solution is that the heatable hose, which runs between the carbamide tank and the pump module, is jacketed in a coat of EPDM into which heating wires capable of carrying electric voltage are integrated.
In this way, both the hose and the medium can be heated and the solution is prevented from freezing.
The heatable reducing agent hose, which can be used as suction and return hose as well as pressure compensation hose, is equipped with an EPDM-based inner lining.
Heating conductors
The electric heating conductors - positioned on a polyester mesh functioning as pressure carrier - encircle the hose, the cover of which is likewise made of EPDM. A low-permeation inner lining ensures that no carbamide can escape from the system. The built-in heating filaments even have the effect of improving the hose's mechanical properties.
One of the major challenges posed and overcome was that of securing the hose's electric contacts against dust, dampness and extreme temperatures.
Here, with the right insulation and sheathing, ContiTech was able to provide for safety, which is so very important for mobile non-road machinery in particular.
The system complies with the IP69 K protection standard and is carbamide resistant up to a media temperature of 85°C. It can be used within an ambient temperature range of -40°C to 130°C, thereby ensuring that the system functions properly even at low temperatures.
This is absolutely essential for an optimum engine setting in terms of exhaust emissions. In the event of a catalyst failure, the system's exhaust gas values would otherwise be even worse than the values with fuel-optimised engine settings.
So here the ContiTech solution makes possible reliable and clean operation regardless of the temperature and the engine setting.
Excellent design know-how is required to adapt the SCR system to the wide variety of industrial applications in which the process is used - ranging from the farm tractor and mobile crane to the power pack. The structural prerequisites into which the ContiTech designers integrate their SCR lines vary as greatly as the applications.
The main challenge is that of optimally connecting the individual components linking the AdBlue tank, the feed pump, and injector. A compromise must be found for the components between flexural stiffness and flexibility.
There are also several approaches to heating the lines. In addition to the tried-and-tested standard method with the integrated heating filaments, the carbamide can also be kept from freezing by using the cooling water. Power units that are used only in mild climates get along entirely without heating.
In co-operation with its partners in industry, ContiTech brings tailor-made solutions quickly to production readiness:
The heatable carbamide lines for SCR technology are without a doubt one of our most successful developments in recent years. With the development through to production readiness, however, the project was far from finished for ContiTech's designers. They remain hard at work to perfect the product and to up new application possibilities.
Continuous optimisation
There has been major progress in particular in the material development. It turned out that the high permeability of the original EPDM jacket was a disadvantage in the automotive sector since it could have resulted in an odour problem in the car - which is not the case in for instance trucks, construction machines or farm implements where the lines are located outside. ContiTech's material developers managed to solve this problem quickly: the hose lining on all ContiTech SCR lines now consists of a low-permeation EPDM/butyl compound jacketed in EPDM. Industrial applications and commercial vehicles also profit from the constant further development.
This has further benefits for the customer. By making advancements in material development and the ongoing optimisation of the manufacturing process, we have been able to not only reduce costs substantially, but also further enhance quality and effectiveness.
Throughout all of Europe, availability of the aqueous carbamide solution has long been ensured. There are AdBlue depots at transport companies and many public filling stations.
In addition to pumps for AdBlue, refill canisters can now be found at many filling stations across Europe. But ContiTech supplies more than just the vehicle lines for SCR technology. The company also produces the tank lines for the network of AdBlue service stations found virtually everywhere.
The pump hose has no adverse effect on the purity of AdBlue. Its distinguishing feature is an ultra-low-diffusion inner lining. The cover is highly resistant to wear and aging.
Low-stretch textile mesh with crossed tin-plated copper strands are used as the tensile member. Because of its ample flexibility, the hose allows for easy handling even when a nozzle is firmly attached to it.
ost-saving, eco- and climate-friendly units make major demands on materials and technology. With new materials and processes, ContiTech Fluid Technology establishes the prerequisites, making a substantial contribution to the realisation of future-compatible vehicle generations with its hoses and hose line systems.
ContiTech AG is a specialist for rubber and plastics technology in the non-tyre rubber sector. The company develops and produces functional parts, components, and systems for the automotive industry and for other key industries.
As a supplier of brake systems, systems and components for the powertrain and chassis, instrumentation, infotainment solutions, vehicle electronics, tyres and technical elastomers, the corporation contributes towards enhanced driving safety and protection of the global climate.
Continental is also a partner in networked automobile communication. The corporation currently employs approximately 134000 at nearly 190 locations in 35 countries.
Enter X at www.engineerlive.com/ape
Georg Franz is with ContiTech AG, Hanover, Germany. www.contitech.de