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The road to recovery â life after Euro 6
Mark Sealy, global engineering director for the commercial vehicle sector of Norgren, a market leader in fluid control technology, looks at the challenges faced by OEMs and Tier 1s as Euro 6 emissions standards come into play
Mark Sealy, global engineering director for the commercial vehicle sector, Norgren
As a provider of valves and fluid management solutions into the commercial vehicle sector, emissions-related projects have dominated our activities over the past six to seven years, with, roughly 80% of R&D investment being spent on achieving compliance. Among the products resulting from this have been exhaust gas recirculation (EGR) solutions, waste gate controls and valves for after-treatment systems while, for Euro 6, our main development has been heavy duty electric inlet throttles which have recently been introduced with two of our larger truck customers.
So, having tackled the challenges of Euro 6, do we have a Euro 7 to look forward to? Probably not, as we have gone as far as is practical in terms of minimizing levels of nitrous oxides and particulates. What is possible is that we may be looking at a ‘Euro 6 Plus’, where optimization and cost reduction of systems will be the goal, so part of future efforts for the industry may well be spent supporting refinement and improvement of the Euro 6 solutions.
We will, however, also be moving onto new agendas. If we consider environmental challenges driven by general human activity, greenhouse gases are expected to have increased by 55% between 1990 and 2020; global demand for generated electricity is up by 40% and the planet will require 50GW of generation capacity in 10 years’ time. By 2050, the market for low carbon energy will exceed US$500 billion and with dynamic shifts in shale gas extraction, the US will be energy-independent as soon as 2020.
Now that we have reached the end of new emissions control targets in the UK, Europe and Japan, the next drivers are set to be CO2 efficiency, cost of ownership and greenhouse gas reduction, which will lead to a different blend of engineering challenges. For those of us in the fluid control industry who have been heavily involved in green engines and after-treatments, we now need to turn our attention to areas such as heat recovery, tire efficiency and alternative fuels, especially natural gas. We also have to consider recent legislation, for example the requirement in India and China for secondary braking, which calls for the use of retarders and exhaust braking equipment.
Increasingly sophisticated systems
Six years ago, the Euro 3 engine was quite simple; by Euro 6 we see the addition of a huge amount of sophistication both in cylinder and after-treatment equipment. Project forward six years, and we will see a powertrain system that is still more sophisticated. One way of putting it is that an engine six years from now will be accompanied by both a chemical plant and a power generation plant, with all systems needing to work harmoniously – this means there are a lot of fluid control challenges ahead.
Last year, legislation was introduced in the Americas requiring a reduction of roughly 17% in CO2 output of the Class 8 fleet in terms of freight-ton-miles by 2018. The reason that this is significant in the US is not only because of environmental concerns and energy dependency but also because of the fact that 72% of US oil consumption is accounted for by vehicle transportation. For Europe, legislation is pending, but the expectation is to reduce greenhouse gases from the transport sector by 20% by 2025.
To consider how we start to meet these challenges, Norgren has talked to OEMs and engine makers, looking at every facet of fuel burn in the pursuit of improving cost of ownership, running costs and CO2. There are many options, but if a pie chart of fuel usage shows that about half the energy from fuel goes out as waste heat. It follows then that the single biggest opportunity to make a difference is heat recovery, using some of the heat from the exhaust, which typically makes up about one third of the fuel’s energy.
Our work on waste heat recovery began around 18 months ago, looking very specifically at Rankine cycle heat recovery systems. Such systems interface with numerous other systems in the vehicle and will replace some of the emissions equipment, meaning we are looking at complex and long timescale-type developments. The question is, are they worth pursuing? Nearly all OEMs have confirmed to themselves that typically on a 350kW engine, about 100kW of heat is accessible and of that, about 30kW is recoverable, which means that on a typical freeway drive cycle, a 5% real life fuel saving would be realistic. As fuel prices continue to increase and as the cost of fuel is typically a truck operator’s largest expense, this suggests it is most certainly worth doing.
Fluid control perspective
What does this mean from the fluid control perspective? The working fluids required for these Rankine cycles are not as yet finalized. Many have been reviewed, but no ideal liquid has yet been found. We are currently supporting programs working with water, refrigerants and alcohols and simply from the levels of interest shown would suggest that the front-runner, at the moment, is ethanol. However, all systems are high-pressure, high-temperature and need to be zero net loss over life, which are quite challenging requirements.
Looking on to alternative fuels, we need to keep a careful eye on natural gas adoption. There is bound to be a dash for gas driven by the fracking process, which is making shale gas more readily available. It is estimated that as soon as 2022 one truck in 10 in Europe, one in five in the US and one in three in China could have converted to natural gas. This is a transformation that is coming at us quickly and the journey is already under way.
So by 2020, we can realistically predict that between 10 and 30% of commercial vehicles will have converted to natural gas. Turbine compounding or Rankine cycle waste heat recovery will be deployed, and elaborate aerodynamics will be common. Low rolling resistance super single tires will pervade with inflation management and auxiliary power units will be utilized to avoid idle time. Automated manual transmissions with retarders will be prevalent and most city trucks will have some level of hybridization. Full electric vehicles will continue to slowly penetrate for urban and suburban cycles while fuel cells will remain a niche, most likely as range extenders on electric vehicles.
But what about beyond 2020? Imagine a vehicle with two fuel tanks one for liquefied natural gas and one for liquefied air. Liquefied air is already reasonably available produced on an industrial scale. It is a working fluid that is non-flammable, produces no emissions, is not ozone depleting, is free and not currently taxed – in all, a pretty good working fluid. The vehicle also has two engines, one a reasonably conventional natural gas engine that burns the gas and produces shaft power and waste heat, and a second engine that expands liquid air, produces more shaft power and, conveniently, consumes the waste heat from the first engine. This engine pair would be mechanically coupled, almost thermally neutral, (in theory, there would be no requirement for a cooling system). Add one final component – a compressor to recover braking energy – and you have an air/ gas hybrid, all achieved with fairly low-tech technology and no expensive electrical systems.
Euro 6 may have more or less drawn a line under emissions control, but for the fluid power industry there is still plenty to think about in the future.