Global emissions standards for non-road and marine diesel engines continue to tighten and fuel filtration will continue to play an important role in meeting these new challenges. North America, Europe, Japan and Korea have been hit hardest, although Brazil, Russia, Turkey, Saudi Arabia, China and India have also witnessed the impact of increasing legislation. To gain a clearer picture of emissions standards, individual regions and vehicle categories need to be analysed.
In Europe, stage IV emissions requirements closely mirror those in the US. Stage IV came into force in 2014, a standard that necessitates emissions to be measured on-engine during both a steady state and transient test cycle
Among many noteworthy points, for the main power sector (130 to 560 kW), the NOx standard is the same between Europe and the US. However, the PM (particulate matter) standard in the US is 20% lower than Europe. What’s more, unlike the US, Europe currently has no limitation for engines over 560 kW in this category. In reality, however, there are very few applications where this would be applicable. For example, a large 560 kW combine harvester would be impractical in Europe, whereas in the US they are commonplace.
There are currently no fixed plans for stage V in Europe, but the expectation is that the sectors below 19 kW and above 560 kW will be regulated. In addition, particulate number standards are expected to bring the standard in line with the on-road legislation.
This article is a small portion of a study conducted by AVL that was commissioned by Parker Hannifin Racor Division. To download the full 44 page report, Summary of Fuel Injection Equipment With Respect to Diesel Fuel Filtration.
Switching focus to non-road legislation for diesel engines in the US, criteria emissions limits reduced steadily from 1996 to 2011. As a consequence, this sector has seen the most significant changes in the shortest time, a development that has driven a total shift in applied technology. The non-road legislation is staggered in four stages (Tiers 1-4), with Tier 4 being the current legislation.
Due to the difference in engine cost at different power levels, the emissions targets are staggered by power band. For instance, it would clearly be cost prohibitive to apply a full heavy duty style exhaust after-treatment system to a light duty engine. Useful emission equipment life requirements also apply depending on engine duty cycle.
Looking to the future for non-road US engines, Tier 5 is not yet defined, but if implemented it may focus on other aspects of the legislation, such as on-board diagnostics, rather than the criteria pollutants.
Away from land-based vehicles, the IMO (International Maritime Organization) regulates emissions from ship exhausts through standards known as Tier I, II and III of MARPOL 73/78.
Tier I was introduced in May 2005 and covers engines greater than 130 kW installed on vessels on or after 1 January 2000 or which undergo major conversions after that date. Tiers II and III were adopted in 2008 and cover new fuel quality specifications, improved NOx standards for existing pre-2000 engines, and globally-based ocean regions and ‘Emission Control Areas’ with specified emission reduction requirements. Actual emission levels are defined by engine rated speed and the area of operation.
Although there are no limits on soot, generally no visible smoke is acceptable. Avoiding smoke requires higher injection pressures, especially at partial load, and therefore high pressure common rail injection systems are increasingly being deployed.
While it’s easy to focus on the requirements for regions that have adopted enhanced criteria emissions standards, lesser regulated markets should not be overlooked when it comes to fuel system demands.
In the industrial engine market it is becoming standard practice to sell the engines/vehicles/machines into lesser regulated countries after several years of operation in the original market. Often ‘de-tier’ kits are applied to the engines to remove systems that are not required in the new market. However, the fuel system is at the heart of the engine and this will normally remain on the vehicle as it enters service in a new market. It should also be noted that fuel quality in these markets can be significantly worse than the original market, therefore the filtration requirements can be different.
In conclusion, all engine sectors from small passenger engines to large marine vessels, have witnessed a focused effort to reduce harmful exhaust emissions. For on-road applications the emissions levels have dropped to the point where further reductions will have smaller environmental impact. As a result, future changes in legislation for harmful emissions will focus on refinements to address specific issues rather than major order of magnitude reductions that have been seen in the past. An example of this could be the introduction of particulate number standards to effectively mandate the use of DPFs (diesel particulate filters) for on-road trucks in the US. However, with harmful emissions standards reaching a plateau, the focus will almost certainly shift towards fuel economy and CO2 reduction. In the past, the main pressure for improved fuel economy has been consumer driven, but now it will be new legislation that mandates fuel economy improvement.
Ultimately, of course, future standards and legislation will only serve to fuel further engine, after-treatment and vehicle technology developments. Moreover, fuel systems will continue to play an important role in the package of technologies being applied to meet the challenge.
For additional information regarding fuel filtration solutions contact Parker Hannifin Racor Division