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Water vapor is, aside from carbon dioxide, the major fossil fuel combustion by-product. Depending on its concentration in the exhaust gas mixture as well as on the exhaust gas pressure, its condensation temperature can be derived. For typical gasoline engine stoichiometric operating conditions, the water vapor dew point lies at about 53 °C. The exhaust gas mixture does however contain some pollutants coming from the fuel, engine oil, and charge air, which can react with the water vapor and affect the condensation process. For instance, sulfur trioxide present in the exhaust, reacts with water vapor forming sulfuric acid. This acid builds a binary system with water vapor, which presents a dew point often above 100 °C. Exhaust composition after leaving the combustion chamber strongly depends on fuel type, engine concept and operation point. Furthermore, the exhaust undergoes several chemical after treatments.

The knowledge of thermal behavior of combustion engines is extremely important e.g. to predict engine warm up or to calculate engine friction and finally to optimize fuel consumption. Typically, thermal engine behavior is modeled using look-up tables or semi-physical models to calculate the temperatures of structure, coolant and oil. Using look-up tables can result in inaccurate results due to interpolation and extrapolation; semi-physical modeling leads to high computation time. This work introduces a new kind of model to calculate thermal behavior of combustion engines using an artificial neural network (ANN) which is highly accurate and extremely fast. The neural network is a multi-layered feed-forward network; it is trained by data generated with a validated semi-physical model. Output data of the ANN-based model are calculated with nonlinear transformation of input data and weighting of these transformations.

The present work involves the technical background of the field of Diesel injection systems of combustion engines and compares the effects of two kinds of remedies (Re-meshing Technique and Linear Interpolation Technique) on mesh deformation. Mathematical formulation of moving grids has been proposed to guide the change of cell volume before. In this study, CFD (Computational Fluid Dynamics) analysis was conducted to study the behaviors of the internal nozzle flow and the characteristics of the spray. An external library concept was introduced to couple the internal nozzle injection process with the spray formation. In addition, all dynamic simulations were performed under a double-axis system. A comparison between simulation and experimental results shows that the integration of the traditional mesh deformation technique with the re-meshing or the linear interpolation technique can repair mesh deformation and further contribute to better simulation results.

Two-cylinder engines not only have special demands concerning uniformity and dynamics of oscillating masses and firing order, but also place very different demands on the turbocharger. With two-cylinder engines, the pulsating influence grows and changes the operation of the turbine. In this paper different boosting technologies are compared in small engine applications. Besides turbochargers the potentials and limits of superchargers and electric chargers are compared as well as their combinations. These technologies show differences concerning power supply, operation range and efficiency, and these effects have different implications in small engines. The efficiency of a turbo compressor, for example decreases, rapidly for small dimensions. Results from experiments and engine process simulations are shown based on a two-cylinder engine of 0.8l displacement. The operating condition of a turbocharger turbine in a two-cylinder engine is very specific due to exhaust pulsations.

Acoustic measurements, especially interesting for new bearing concepts such as ball bearings, are an important part of the evaluation of turbochargers. Typically, acoustic benchmarking is done at standard conditions, neglecting possible negative effects of very low temperatures, as they might be encountered in real-world applications. For realistic turbocharger measurements at cold environment conditions down to −10 °C, special adjustments to the turbocharger test bench have been made. This article introduces a soundproofed climate chamber built in the turbocharger test bench which is able to achieve low component and oil supply temperatures while still providing adequate conditions for acoustic measurements. In the first part of the paper, the concept of the acoustic climate chamber is presented. Layout calculations are shown as an indicator for the performance of the acoustic and thermal isolation.