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A comprehensive experimental and theoretical approach was undertaken to understand the phenomenon of pre-ignition and to assess parameters to improve or even eliminate it completely. Oil mixing with fuel was identified as the leading theory of self ignition of the fuel. End of compression temperature has to meet a minimum level for pre-ignition to take place. In this work a comprehensive list of parameters were identified that have a direct and crucial role in the onset of pre-ignition including liner wetting, injection targeting, stratification, mixture motion and oil formulation. Many secondary effects were identified including ring dynamics, ring tension, spark plug electrode temperature and coolant temperature. CFD has been extensively used to understand test results including wall film, A/F ratio distribution and temperature at the end of compression when looked at in the context of fuel evaporation and mixing.

Automotive OEMS are continuously working on improvements of their vehicle development processes, to improve quality, reduce lead time and cost. In particular the enhancement of virtual methods is crucial for manufacturing engineering to enable the elimination of physical prototype builds and thus to reduce development cost and time. By analyzing the main issues in reduction of physical builds, compliant parts were identified as being most critical, since their digital representation does not coincide with the reality, so that many changes needed to be made after first hardware validation. As input for compliant part analysis software the material properties have to be specified to allow simplified handling of these parts as homogeneous objects. This is a completely new task for automotive industry, since this data was not needed before and is thus unknown.

The development of virtual techniques becomes more and more important for the automotive industry to allow an acceleration of the vehicle development and the reduction of hardware prototypes. By analyzing the main problem points arising on the first hardware builds it came out, that compliant parts are most critical, since their digital representation does not coincide with the reality, so that many changes are made after first hardware validation. Already some years ago GM has started to work together with the Fraunhofer-Chalmers Centre in Gothenburg, Sweden, on the development of the software Industrial Path Solutions (IPS). At one side the enhancements of the software itself build up the basis for investigations of cables, hoses etc, at the other side in particular for this kind of simulation the industry itself has to invest a lot effort for the effective application of the software. To allow the effective usage of compliant part software load cases were defined.

This paper will examine a mobile air conditioning (MAC) system optimized for efficiency as well as evaporator cooling capacity. Different internal heat exchanger (IHX) capacities and various thermostatic expansion valve (TXV) parameters will be applied using R1234yf refrigerant. Factors that will be considered include IHX heat transfer and pressure drop, TXV superheat setting and slope, the effect of oil in circulation and how these factors impact the efficiency and capacity of the MAC system. The paper describes the test facility used and the test procedures applied.

Increasingly stringent CO2 emission standards have been legislated; in part to encourage OEM's to develop more efficient propulsion systems. These development efforts have typically focused on improving steady state operation, but recently there has been increased interest on the improvement potential during dynamic behavior. In particular the warm-up behavior of combustion engines is a field of increasing investigation. This warm-up behavior is especially pertinent in Europe, where customers tend to drive shorter distances, and the New European Driving Cycle (NEDC) reflects this driving pattern. The desire to influence this warm-up behavior is typically referred to as thermal management. Thermal management may be considered as “heat brokering” where the optimum flow of heat is to be decided, e.g. take heat from exhaust or coolant and feed it to coolant or oil. The goal is to reduce fuel consumption by achieving the most efficient warm-up of the powertrain.