An experimental study has been carried out to provide qualitative and quantitative insight into gas to wall heat transfer in a gasoline fueled Homogeneous Charge Compression Ignition (HCCI) engine. Fast response thermocouples are embedded in the piston top and cylinder head surface to measure instantaneous wall temperature and heat flux. Heat flux measurements obtained at multiple locations show small spatial variations, thus confirming relative uniformity of incylinder conditions in a HCCI engine operating with premixed charge. Consequently, the spatially-averaged heat flux represents well the global heat transfer from the gas to the combustion chamber walls in the premixed HCCI engine, as confirmed through the gross heat release analysis. Heat flux measurements were used for assessing several existing heat transfer correlations. One of the most popular models, the Woschni expression, was shown to be inadequate for the HCCI engine. The problem is traced back to the flame propagation term which is not appropriate for the HCCI combustion. Subsequently, a modified model is proposed which significantly improves the prediction of heat transfer in a gasoline HCCI engine and shows very good agreement over a range of conditions.

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New Heat Transfer Correlation for an HCCI Engine Derived from Measurements of Instantaneous Surface Heat Flux

Internal-combustion engine heat transfer

Experimental study of various effects of exhaust gas recirculation (EGR) on combustion and emissions of an automotive direct injection diesel engine

Use of hydrogen to enhance the performance of a vegetable oil fuelled compression ignition engine

A comparison of water–diesel emulsion and timed injection of water into the intake manifold of a diesel engine for simultaneous control of NO and smoke emissions

Advanced Approaches for Heat Transfer Calculations

This study shows the newest results of a near-series pre-turbo-catalyst (PTC) system reaching lowest emissions for electrified diesel passenger cars to address future emission legislation. The PTC system is developed using a state-of-the-art tool chain containing 1D & 3D simulation approaches and testing near-series exhaust gas aftertreatment systems under real-driving boundary conditions. The innovative concept of a selective catalytic reduction (SCR) PTC and a PTC bypass path solve the challenge of a thermal handshake between PTC and underfloor SCR System as well as the challenge of a particular filter regeneration. The development of adaptive PTC bypass path operation strategies based on exhaust gas and catalyst conditions enables lowest NOx and NH3. Using this concept, zero-impact NOx emissions, that don’t impact cities air quality, can be reached in a wide range of operating scenarios while sustaining full drivability and highest efficiency. Advanced catalyst technologies enable a high emission conversion and lowest secondary emissions. These results have been achieved in the context of the “INES” (“Intelligentes Niedrigstemissionssystem für die Diesel PKW Anwendung”) project, funded by the Bundesministerium für Wirtschaft und Klimaschutz, Ministry for Economic Affairs and Climate Action (BMWK) and addresses research of future mobility requirements.

Günter F. Hohenberg

Papers

Advanced Approaches for Heat Transfer Calculations

A Holistic Approach For Near Zero Emission Diesel Vehicles Using A Pre-Turbo-Catalyst-System – Ready For EU 7