With the ever-increasing pressure to create a greener future, car companies and engine producers alike are always looking for new and improved fuels and technologies to reduce their footprint on the environment. Here at UW-Madison, the Engine Research Center (ERC) and the Hybrid Vehicle team have joined forces to develop and implement a revolutionary dual fuel technology: reactivity controlled combustion ignition (RCCI).
A variant of more common compressive fuel technology, RCCI is the combination of at least two fuels with different reactivity, or propensity to react, separately injected into an engine separately. Possible fuel combinations include mixtures of gasoline, diesel and ethanol in various, unique proportions. The lower reactivity fuel is injected first and is allowed to disperse uniformly in air. The higher reactivity fuel is then injected directly into the combustion chamber. The fuel potpourri is then ignited and provides the energy required to operate the engine.
Taking a closer look at the reaction occurring inside the engine provides the porthole to RCCI’s enormous benefits. Mixing two fuels instead of using just one allows the reaction to happen at a much lower temperature and greatly maximize the energy efficiency of the engine. The two fuels also pair up in a stoichiometric fantasy of efficiency, as each fuel now has an opposite to combine with, leaving very little fuel wasted or worse, released into the atmosphere as a byproduct.
Harmful emissions are always the base measuring point for how “green” a technology is. Again, RCCI passes with flying colors and easily surpasses the most recent vehicle emission standards. The fresh air that was originally brought into the engine with the low reactivity fuel is much more likely to react with residual carbon, creating carbon dioxide instead of harmful soot, NOx gases, or particle pollution. After a fairly simple implementation, the RCCI technology gets the best of both worlds, creating a lean diesel at an efficient clip .
Despite all these perks, there of course are reasons the technology is still in its infant stages of development. In accordance with the ideal gas law, for the reaction of the two fuels to take place at such low temperatures, the gases must be compressed to extreme pressures. To become a viable technology, the pressures in each cylinder would have to be constantly monitored by computers, which would then make decisions based on those pressure readings. Computers are not cheap, and this technology is no exception.
As with so many groundbreaking ideas, inherent costs have the potential of RCCI tethered for the time being. The key phrase here is “for the time being.” As the Roman philosopher Seneca said, “Difficulties strengthen the mind, as labor does the body.” Graduate students led by Professor Rolf Reitz in the Engine Research Center here at UW-Madison understand this better than most. After applying for a patent for the technology in 2010, they continue to put in physically and mentally tiring hours in labs refining RCCI.
According to Mechanical Engineering Master’s Degree candidate Shawn Spannbauer, at least half of the labs in the research center are dedicated to RCCI. “It’s really the research center’s cash-cow,” Spannbauer says in true Wisconsin form. The research is funded by the Department of Engineering as well as the College of Engineering Diesel Emissions Reduction Consortium, a conglomerate of 24 major industry partners.
While the ERC provides the technology, the UW-Madison Hybrid vehicle team will provide the implementation. Headed by team leader Jake Riederer, the Hybrid team is currently working on two cars to run on an RCCI engine. No stranger to success, the Hybrid team has won the Department of Energy’s Advanced Vehicle Competition six times in the last two decades. Now they’re switching gears to convert two of their competition cars to work with the groundbreaking technology. One car will run an RCCI engine and an electric generator in series (meaning one engine will provide power to the other). The second car will function in parallel (both engines operating simultaneously). They hope to have the series car functioning by the end of the school year. Riederer notes, “As far as we know we’ll be the first to successfully run a car with an RCCI engine.”
Being at the cutting edge of their respective fields is nothing new for the Hybrid Vehicle team or the Engine Research Center. Despite the challenges ahead, both Riederer and Spannbauer are confident that it won’t be too long before RCCI takes off and literally fuels the cars of tomorrow. Until then, the two groups will continue to refine and perfect their proprietary technology and reinforce UW-Madison’s image as one of the top research universities in the nation.