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Despite the fact that urea-based selective catalytic reduction (SCR) of NOx is a key technology for achieving on- and off-highway diesel emission standards, significant control challenges remain. Transient operation, combined with dramatic changes in catalyst dynamics over the operating range, cause highly nonlinear system behavior. Moreover, these effects depend on catalyst formulation and new catalysts continue to be developed. With many controllers, any difference in catalyst formulation, converter size, and engine emissions calibration require control system re-tuning. To minimize control development effort, this paper presents a novel “generic” controller for SCR systems. Control action is grounded in a physics-based, nonlinear, embedded model. Through the model, controller parameters are adjusted a priori for catalyst formulation and converter size. The few remaining tuning levers are quite intuitive, and require no special knowledge of controls theory.

Cooled EGR continues to be a key technology to meet emission regulations, with EGR coolers performing a critical role in the EGR system. Designing EGR coolers that reliably manage thermal loads is a challenge with thermal fatigue being a top concern. The ability to estimate EGR cooler thermal fatigue life early in the product design and validation cycle allows for robust designs that meet engine component reliability requirements and customer expectations. This paper describes a process to create an EGR cooler thermal fatigue life model. Components which make up the EGR cooler have differing thermal responses, consequently conjugate transient CFD must be used to accurately model metal temperatures during heating and cooling cycles. Those metal temperatures are then imported into FEA software for structural analysis. Results from both the CFD and FEA are then used in a simplified numerical model to estimate the virtual strain of the EGR cooler.

In order to meet future emissions standards, diesel engines may require the use of exhaust gas recirculation (EGR). The NOx-bsfc trade-off can be improved by using an exhaust-to-engine coolant heat exchanger. If care is not taken, the durability of the cooler may be compromised by sulfuric acid condensation from the exhaust gas. This paper presents a computer model for predicting the dew-point, acid condensation rate, and condensate composition inside an EGR cooler. Effects of fuel sulfur content, pass arrangement, surface fouling, coolant temperature, and engine operating point on acid condensation were identified by applying the model to a prototype heat exchanger.