A Comparison of Heat Transfer and Spray Characteristics for a Model Fuel and Standard Diesel Interacting with a Temperature-Controlled Wall

Paper in proceeding, 2006

The objective of this work is to compare the heat transfer and liquid penetration of two different diesel fuels when they impinge on a temperature-controlled wall. The study was performed in a high pressure, high temperature spray rig at conditions corresponding to a direct injected diesel engine. Two fuels were used in this study, a standard diesel fuel and a two-component model fuel. The temperature-controlled wall on which the fuel impinged was mounted at different distances downstream of the nozzle in the spray chamber. It was equipped with four coaxial thermocouples for recording the surface temperature. The thermocouples had a vacuum deposited junction that offered a response time of approximately \unit{3}{\micro\second}. Recorded time histories of the surface temperatures showed that the two fuels have a similar heat transfer at two different wall temperatures. It could also be seen that wall and air temperature had a great influence on the heat transfer. The spray characteristics were measured with a Phase Doppler Particle Analyzer and high speed imaging. Image analysis showed that the two fuels have a similar penetration even though both methods showed that the model fuel, Idea, evaporates faster. PDPA data show that the axial mean velocity behaves the same close to the spray centre but changes further out. The radial (mode) velocities are mainly dependant on height position for both fuels. The droplet diameter is larger for the diesel fuel at all positions, probably because of a stronger evaporation of the model fuel.