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Fouling in EGR coolers occurs because of the presence of soot and condensable species (such as hydrocarbons) in the gas stream. Fouling leads to one of two possible outcomes: stabilization of effectiveness and plugging of the gas passages within the cooler. Deposit formation in the cooler under high-temperature conditions results in a fractal deposit that has a characteristic thermal conductivity of ∼0.033 W/m*K and a density of 0.0224 g/cm3. Effectiveness becomes much less sensitive to changes in thermal resistance as fouling proceeds, creating the appearance of “stabilization” even in the presence of ongoing, albeit slow, deposit growth. Plugging occurs when the deposit thermal resistance is several times lower because of the presence of large amounts of condensed species. The deposition mechanism in this case appears to be soot deposition into a liquid film, which results in increased packing efficiency and decreased void space in the deposit relative to high-temperature deposits.

The CRC Fuels for Advanced Combustion Engines working group has worked to identify a matrix of research diesel fuels for use in advanced combustion research applications. Nine fuels were specified and formulated to investigate the effects of cetane number aromatic content and 90% distillation fraction. Standard ASTM analyses were performed on the fuels as well as GC/MS and1H/13C NMR analyses and thermodynamic characterizations. Details of the actual results of the fuel formulations compared with the design values are presented, as well as results from standard analyses, such as heating value, viscosity and density. Cetane number characterizations were accomplished by using both the engine method and the Ignition Quality Tester (IQT™) apparatus.

As interest has grown in diesel emissions and diesel engine aftertreatment, so has the importance of analyzing all components of the exhaust. One of the more costly and difficult measurements to make is the collection and analysis of semivolatile organic compounds (SOCs) in the exhaust. These compounds include alkane and alkenes from C12-C24, and the 2-5 ring polycyclic aromatic hydrocarbons (PAH). These compounds can be present in both the particulate (i.e. on the filter) and gaseous phase, and cannot be collected with bag samples. Typically, a sorbent is used downstream of the particulate collection filters to collect these compounds. Sorbent phases include polyurethane foam (PUF), Tenax™, XAD-type resins, and activated carbon. The SOCs are removed from the sorbent either by solvent extraction (PUF and XAD) or thermal desorption (Tenax™ and activated carbon). Each of these methods have advantages and disadvantages.