Experimental Results

 

A 1.6L DaimlerChrysler S.I. engine has been set up to study the convective boiling heat transfer in the engine cooling system. Ten K-type thermocouples were installed in the metal between the gas chamber and the coolant channel at the exhaust-exhaust valve bridges (hot spots) in the cylinder head.  The experimental data have been taken along with variations of RPM, coolant temperatures and system pressures. Throughout the data reduction, the thermal conductivity of 113 W/m.K for the aluminum cast of the cylinder head, which was given by DaimlerChrysler, has been used. Valvoline G-05 Antifreeze coolant has been used as coolant throughout the experiments. The vapor pressure curve of the G-05 coolant was compared to the ethylene-glycol/water 50/50% volume within approximately 2% discrepancy according to the property data provided by the Valvoline Co..

 

Thermocouple locations in Cylinders 1 and 4 at exhaust-exhaust valve bridge.
Thermocouple locations in Cylinders 2 and 3 at exhaust-exhaust valve bridge.
Data 20020918 (2000 RPM. 3000 RPM, and 5600 RPM) Metal temperatures Throttle position Torque and horsepower Coolant Pressure Volume flow rate Exhaust gas temperatures Coolant Temperature Extrapolated coolant wall temperature Estimated Heat flux Estimated convection heat transfer coefficient Extrapolated gas face temperature Temperature versus distance from gas face to coolant wall at exh-exh. valve bridge for cylinder 3 Gas face, metal, and coolant wall temperatures for cylinder 3 Effect of pressure on coolant wall temperature at exh.-exh. valve bridge for 5600 RPM
Unsolved problem Pressure was intentionally dropped from 41 psig to 11 psig of engine inlet during steady running for three engine speeds, 2000, 3000, and 5600 RPM. It is noticed that the coolant flow rate at 5600 RPM accordingly dropped consistently from 35 gpm to 25 gpm, while no drops were detected for both 2000 RPM and 3000 RPM. It is believed that the drop of coolant flow rate at such a high engine speed might be associated with cavitations (bubble formation and collapse) in water pump impeller due to the pressure drop causing a decrease in saturation temperature. This phenomenon is under investigation.

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