SwRI engineers help develop post-refinery diesel treatment that overcomes soot/NOx tradeoff for cleaner burning fuel
Southwest Research Institute (SwRI) is helping a client develop a simple post-refinery treatment process that reduces exhaust emissions from diesel engines by overcoming the soot/nitrogen oxides (NOx) reduction trade-off that has plagued engine researchers for decades. The result is a modified fuel that potentially could replace today’s ultra-low sulfur diesel, biodiesel and other renewable diesel fuels.
Internal combustion engines, when burning a fuel-air mixture, produce harmful pollutants such as soot and NOx. To decrease emissions, engineers design and calibrate engines to adjust combustion temperatures, but have been stymied by the soot/NOx trade-off. Attempts to reduce soot with increased temperatures results in higher NOx, and lowering the temperature has the opposite effect. The modified fuel reduces soot production without increasing NOx and without requiring engine design or calibration changes.
Although engine manufacturers routinely develop cleaner engines for new vehicles, older model vehicles continue to contribute heavily to pollution levels. This new modified fuel could potentially lower exhaust NOx and particulates for both older and newer model diesel engine vehicles.
While fossil fuels eventually may be replaced by electric powertrains or noncarbon fuels in our lifetime, the process developed with our client could be implemented immediately.—Project manager James Wood, a principal scientist in SwRI’s Chemistry and Chemical Engineering Division
SwRI did all of the developmental work for this technology, including development of chemical formulations and processing the mixture in a small-scale unit.
This internationally patented technology introduces a unique low concentration chemical treatment that is combined with a specialized mechanical mixing system that produces a treated diesel fuel that is stable for long periods of time.
The method of the present invention comprises mixing and homogenizing diesel fuel with two special additives and submitting the mixed and homogenized mix to controlled cavitation inside a Shock Power Reactor having a rotor, in order to obtain an improved bipolar diesel fuel. Using the improved diesel fuel in internal combustion engines allows a reduction of the total soot and total PM emissions by more than 30% as well as total Nitrogen Oxides (NOx) emissions. The improved diesel fuel breaks the tradeoff of NOx and soot production in a diesel combustion engine with a fuel penalty of from 0 to 3%.—“Process for the production of an improved diesel fuel” CA3125557A1
As described in the patent document, the improved diesel fuel is based on commercial diesel with the addition of two mixtures of components: an ethoxylated fatty acid ester; and a complex water based mixture formed by aromatic solvents such as para “p-” or ortho “o-” xylene with one or two methyl radicals mixed with a balance of four ethoxylated phenol derived surfactants that can be alkyl type chains or nonyl type as well.
The first is a non-polar substance and the second is a bipolar mixture. Both substances create a complex molecular dispersion with diesel fuel or ultra-low diesel fuel. Both additives are injected to the main process flow and mixed thoroughly by means of a Shock Wave Power Reactor (SPR).
This establishes a blend-in process that easily modifies the fuel. The specimens demonstrated conformance to ASTM physical, mechanical, rheological, thermal and chemical fuel requirements.
SwRI’s Powertrain Engineering Division evaluated the fuels during steady-state and transient engine emissions testing according to Environmental Protection Agency test procedures.
The modified fuel resulted in a substantial reduction in soot mass emissions compared to the baseline ultra-low sulfur diesel.—Dr. Imad Khalek, a senior program manager who operates SwRI’s particulate laboratory
Based on the bench-scale plant, SwRI helped design a production-scale facility that meets ASTM International and ANSI (American National Standards Institute) standards and is capable of processing 12,000 barrels per day (150 million gallons per year).
Work on this project began about eight years ago with initial proof-of-concept and then the development of a pilot plant. More recently, SwRI has led a fuel formulation investigation project and fuel production procedures development for the client. The modified fuel has undergone evaluation in real-scale heavy-duty certification engines and is available for commercial development.