Delphi bulks up biofuel compatibility
One of the issues they are addressing is corrosion resistance when dealing with ethanol blends. The ethanol itself is evidently not corrosive, the problem comes from the fact that ethanol has a tendency to absorb water. The water absorbs corrosive salts and that's what actually causes the damage. For more on what Delphi is working on check out the press release after the jump.
Delphi Builds Global Expertise In Biofuel Compatibility
A combination of research programs and world-leading field experience is helping Delphi ensure that its fuel systems customers are ready for rapid growth in the use of biofuels in every region
LUXEMBOURG Feb 15, 2007 -- Delphi Corporation has stepped-up its global research into the many engineering challenges underlying the rapid growth in biofuel usage.
The intention is to ensure that all Delphi fuel injection and fuel handling technologies meet the requirements of vehicle manufacturers for compatibility with high biofuel ratios ahead of market and legislative demand. The company has already supplied ethanol-compatible components for approximately 2.5 million vehicles worldwide and has uprated its diesel injection systems to be compatible with a 5 percent bio mix.
Delphi sees substantial and rapid growth in the market for biofuel-compatible technologies. "For both environmental and economic reasons, the widespread use of biofuels in all significant markets seems certain," said Guy Hachey, president of Delphi Powertrain and vice president Delphi Corporation. "We intend to build on Delphi's world-leading experience in biofuel compatibility to ensure that our customers are ready to answer this growing need with reliable, affordable products."
The most common biofuel in the United States is ethanol, which is typically made from corn and blended with gasoline in a 10 percent mix known as E10.
In 2005, more than 4 billion gallons of ethanol were sold in the United States for blending into automobile fuels. Ethanol production, heavily subsidised by the U.S. Government, is expected to increase by 50 percent by the end of 2007, as is the use of both E10 and E85 (85 percent ethanol).
Ethanol mixes bring many benefits. They have a high oxygen content, which promotes a cleaner burn with less smog-producing emissions and substantially less CO2 (the exact reduction is heavily debated due to the variable amounts of CO2 released during the different ethanol production processes. Around 18 percent is likely, according to professor Daniel Kammen in his report published in the September 2006 edition of Scientific American). Bio ethanol production also helps to reduce the country's dependence on oil imports.
In Europe, there is currently almost no usage of bio-ethanol fuels but a substantial and growing use of biodiesel. Usually made from rapeseed, a 20 percent blend of bio and mineral diesel (B20) can reduce smoke and particulates by 10 percent to 20 percent, and carbon monoxide by up to 20 percent, again due to the relatively high oxygen content of the biofuel.
When combined with other environmental and economic benefits, these performance levels have encouraged the European Commission to issue Directive 2003/30/EC. This directive sets an indicative target of 5.75 percent renewable fuel (by energy) for transport applications by the end of 2010 and 8 percent by 2015. Several European countries, notably France and Germany, have even more ambitious plans.
World-leading experience with ethanol
Biofuels bring many benefits - but they also present significant engineering challenges. For bioethanol, the biggest is the aggressive nature of the fuel in the vehicle tank. Biodiesels bring different challenges and may also generate more NOx.
Delphi has been very fortunate to be intimately involved with one of the world's most comprehensive biofuel programs. As the leading supplier of fuel injection systems for the Brazilian market, where gasoline sales are almost entirely E25 and even E100 is gaining popularity, Delphi has acquired a unique insight into the affects of biofuels over very high mileages. More than 90 percent of new vehicles sold in Brazil feature an engine that operates with ethanol and gasoline at any mix.
"People often say that the biggest problem with high ethanol contents is that it is very corrosive, but this isn't true," said Julie Galante-Fox, a biofuels specialist at Delphi's technical centre in Rochester, Mich. (USA). "The biggest issue is that ethanol is hygroscopic. It absorbs water easily, which causes the fuel to dissolve corrosive salts from any available source it comes into contact with. It's not the ethanol that is corrosive, it's what it brings with it."
Water can come from poor quality fuel storage and distribution systems or it can be intentionally added as it is with Brazilian E100. Corrosive salts can come from a variety of sources. With E10 in the United States, the problem is not significant unless the fuel is highly contaminated, but systems running on variable quality E85 fuels must be carefully specified if durability (and warranty performance) is to match levels set for systems used with standard fuels.
One of the key design skills is materials selection, an area where the Brazilian experience has given Delphi world-leading expertise. Materials used for fuel system components, such as metals, elastomers and plastics, must be compatible with ethanol and with the impurities delivered to the fuel blend by the ethanol.
Already, all of Delphi's gasoline fuel injection systems sold worldwide have been upgraded to deliver 100,000 mile plus durability on E25, even with realistic levels of impurities. Stainless steels have replaced mild steels and vulnerable polymers and elastomers have been replaced with new, high-durability materials or eliminated through innovative design. Current research is focused on delivering similar reliability and safety with E85 without significantly increasing system costs.
Electronics is also playing a significant role. Delphi's bi-fuel Engine Control Module already automatically detects the ethanol ratio in the tank and adjusts fuel and spark controls to optimise efficiency. The company is also using its experience to help its customers develop new calibrations that are optimised to give excellent starting, driveability and emissions on ethanol contents of 25 percent and above. An as yet confidential solution is being developed to ease cold starting with ethanol contents of 85 percent and above. With hardware and electronics, the aim is to offer a range of affordable solutions so that Delphi's customers can select the ones most suited to the conditions their vehicles operate in.
Engineered reliability for biodiesel
The challenges presented by biodiesels are significantly different and start at ratios as low as ten percent (B10).
Again, handling and storage is a big issue. Biodiesel has the advantage of being biodegradeable so is less environmentally damaging if spilt. However, this characteristic allows the fuel to degrade very quickly, particularly if stored in moist or warm conditions. Biodiesel is also more susceptible than other fuels to the growth of bacterial content. Research has shown considerable variation in the quality of biodiesel at retail pumps.
As with ethanol, biodiesel can pick up water, which accelerates chemical degradation of the fuel. Biodiesel is also an excellent solvent, dissolving existing deposits from distribution pipes and tanks and carrying it into the tiny conduits of the fuel system. Insoluble polymers and products of age-related degradation can lead to injector coking, filter clogging and deposits in the fuel system. It also attacks many widely used materials groups, particularly the elastomers used in hoses, gaskets and seals. Peroxides, an oxidation product formed when the biodiesel reacts with oxygen, can lead to embrittlement of some elastomers, which may also become soft or swell.
The physical characteristics of the fuel also create problems. A higher modulus of elasticity can lead to higher injection pressures and reduced service life while poor flow characteristics occur from temperatures as high as 0°C.
Another potential problem with biodiesel is lacquering, which can occur anywhere in the fuel system. The most likely location is around high-pressure injection nozzles where the very high temperatures can cause a reaction of the organic material, leading to a build-up of potentially harmful organic deposits.
"This is a considerable list of challenges for fuel system engineers," said Dr. Detlev Schoeppe, Delphi Diesel director of engineering. "We also have to accommodate considerable variation in both physical and chemical characteristics as the fuel properties are heavily dependent on the production materials and the quality of delivery and storage."
To understand these challenges, Delphi is conducting an extensive international bench testing program with fuels at concentrations from B10 to B100. It is also conducting high mileage fleet testing in partnership with its customers and end users in each sector: trucks, off-highway and passenger cars / light commercials.
Currently all Delphi systems are compatible with B5 and the company is developing injection systems compatibility with significantly higher biofuel contents. "Many vehicle manufacturers are suggesting that warranties will be invalidated if a blend of more than 5 percent biodiesel content is used. We have to help them move this proportion up without any impact on costs, reliability or customer satisfaction," says Schoeppe.
A good example of Delphi's approach, which uses clever design to deliver simple, reliable solutions, is the new capacitive fuel level sensor. Traditional level sensors use a mechanical system that is particularly vulnerable to aggressive fuels. Delphi's new sensor has no moving parts and can measure gasoline, diesel and biofuels without component or software changes, allowing a single part number to be used for all types of fuel.
Ongoing biodiesel research
Delphi currently has a range of biodiesel-related research projects. These include studies of the fundamental parameters affecting biodiesel performance such as deposit formation and aging, pump durability and performance tests, through to engine and vehicle tests in several locations around the world.
An example, at Delphi's Diesel Heavy Duty Technical Centre in London, is a 12-litre engine pounding a typical heavy truck duty cycle fuelled by B30 diesel. After several hundred hours the advanced Delphi EUI fuel injection system will be stripped and examined, re-assembled and installed for another long period of typical hard usage.
"Heavy duty applications impose substantially greater demands on the engine than light duty," said Delphi Diesel Heavy Duty chief engineer David Draper. "We expect our injection systems to work reliably at exceptional pressures (up to 2,500 bar from 2007) and deliver 1 million mile durability with zero maintenance. It's the ultimate test for any automotive technology so makes an ideal research area to increase Delphi's knowledge of biofuels."
Following the trial, components will be taken apart and examined in minute detail. "We will be looking for signs of increased wear in areas such as the injector pin seat and for signs of degradation to metal, polymer and elastomer components," said Draper. The information will be used to ensure that Delphi's fuel systems continue to be a step ahead of developments in biofuel usage, giving vehicle and engine manufacturers the reliability and compatibility they need into the future.
For more information about Delphi, visit the Virtual Press Room is at www.delphi.com/media.
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