Comparison of Boiling Curves between a Standard S.I. Engine and a Flow Loop for a Mixture of Ethylene Glycol and Water

The local measurements of heat flux and coolant wall temperature at the thermally critical areas in a standard 1.6L S.I. engine provided the boiling curves for a 50/50 mixture by volume of ethylene glycol and water. The actual coolant passages at the critical areas in the engine cooling system were examined both visually and numerically in order to construct a flow-loop test apparatus representative of the engine for detailed study with certainty. Precision measurements using a rectangular channel locally heated only from the bottom of the channel were conducted. Comparisons between the engine data and the flow-loop data, using the boiling curves, provided good agreement. Two important points are deduced from the comparisons: (1) The present flow loop represents the actual coolant passages well at the thermally critical areas of the standard S.I. engine, and (2), the reliability of experimental data obtained in the engine, considering both the inherent uncertainties in the measurements and the assumptions made in the present work, is justified by the agreement.