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Pneumatic hybridization of internal combustion engines may prove to be a viable and cost-efficient alternative to electric hybridization. This paper evaluates the effects of pneumatic hybridization of various engine concepts using the criteria of fuel efficiency, driveability, emissions, and cost efficiency. The most promising engine concept is found to be the pneumatic hybridization combined with downsizing and supercharging spark-ignited engines. With this concept, a fuel consumption reduction of over 30% compared to a standard engine with the same rated power can be achieved. The poor driveability usually associated with heavily downsized and supercharged engines is completely overcome by injecting additional air during transients. The most important design issues for this new concept are discussed and several possible solutions are presented. Following these considerations, the first fully functional hybrid pneumatic engine was realized.

In practical applications of ammonia SCR aftertreatment systems using urea as the reductant storage compound, one major difficulty is the often constrained packaging envelope. As a consequence, complete mixing of the urea solution into the exhaust gas stream as well as uniform flow and reductant distribution profiles across the catalyst inlet face are difficult to achieve. This paper discusses a modeling approach, where a combination of 3D CFD and a lumped parameter SCR model enables the prediction of system performance, even with non-uniform exhaust flow and ammonia distribution profiles. From the urea injection nozzle to SCR catalyst exit, each step in the modeling process is described and validated individually. Finally the modeling approach was applied to a design study where the performance of a range of urea-exhaust gas mixing sections was evaluated.

Basic knowledge about the reaction kinetics of the selective catalytic reduction (SCR) as well as measurement data from a dynamometer are used for the design of a physical mean-value model of an SCR catalytic converter system. The converter system consists of an injection device for urea solution and a coated metallic honeycomb-type converter. It is mounted in the tailpipe of a mobile, heavy-duty diesel engine. The core of the catalytic converter model is a series of identical SCR cells describing the thermal and chemical behavior of the SCR catalytic converter. It may be used to design dynamic, model-based feedforward controllers for the injection of reducing agent. Measurements on the dynamometer show that these controllers significantly improve the performance of the SCR system.

In this paper a novel IC engine load-control device is described which actively throttles the intake air and thereby produces electric power. The main component is a small axial turbine that replaces the conventional throttle. This turbine is connected with an electric generator and an appropriate electric load control system. This paper describes the complete system including the turbine, the control system, and the necessary auxiliary parts. A prototype of the proposed system has been realized. The paper shows the results in electric power generation obtained with this prototype in steady-state driving conditions and in standard test cycles. Moreover, extrapolations of the expected benefits in other engine-vehicle combinations are computed using mathematical models of the main parts of the system.