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An experimental study was conducted to measure the heat transfer in a direct injection 2.3 ℓ single cylinder diesel engine. The engine was operated at speeds ranging from 1000 to 2100 RPM and at a variety of loads. The heat transfer was measured using a total heat flux probe, operating on the principle of a thin film thermocouple, sensitive to both the convective and radiative heat flux. The probe was located in the head at two locations: opposite the piston bowl and opposite the piston crown (squish region). The measurements showed about twice as large peak heat flux in the bowl location than in the crown location for fired conditions, while under motoring conditions the relationship was reversed and the peak heat flux was slightly higher in the crown position. The experimental profiles of total heat flux were compared to the predictions obtained using a detailed thermodynamic cycle code, which incorporates highly resolved models of convective and radiative heat transfer.

An experimental study was conducted of the heat radiation in a single-cylinder direct injection 142 diesel engine. The engine was operated at speeds ranging from 1000 to 2100 RPM and a variety of loads. The radiation was measured using a specially designed fiber-optics probe operating on the two-color principle. The probe was located in the head at two different locations: in one location it faced the piston bowl and in the other it faced the piston crown. The data obtained from the probe was processed to deduce the apparent radiation temperature and soot volume concentration as a function of crank angle. The resultant profiles of radiation temperature and of the soot volume concentrations were compared with the predictions of a zonal heat radiation model imbedded in a detailed two-zone thermodynamic cycle code. The agreement between the model and the measurements was found to be good, both in trends and in magnitudes.