Osman, A., Hussin, M., and Zainal Abidin, S., "Testing and Development of an Enhanced and Cost Effective Engine Split Cooling Circuit," SAE Technical Paper 2015-01-1650, 2015, doi:10.4271/2015-01-1650.
The drive to reduce CO2 and fuel consumption from passenger cars requires improvements from various subsystems. In particular, the ever growing importance of effective and efficient thermal management will no doubt benefit the quest for more efficient vehicle. While many established automakers have decided to increase the sophistications of the engine cooling circuits through electronics, the increase in complexity and costs are still not desirable especially for A and B passenger car segments. With this in mind, simple mechanical based cooling systems with enhanced functionalities are in high demand. To meet such demand, a simplified engine split cooling circuit previously proposed, simulated and reported seems to be promising. To further verify the indicated advantages, a prototype unit was built and physically tested using a dynamometer with motoring capability. The test results obtained are encouraging with several distinctive advantages over the conventional serial and parallel cooling circuits. With low circuit pressure losses, the cabin heater can be placed in between the engine and radiator thus eliminating the need for as much as 40 LPM of coolant to be returned to the water pump to avoid flow stagnation. With a lot more coolant flow going to the radiator, the standard water pump pulley was replaced with a bigger one to reduce the flow rate and the pump's power consumption. Engine FMEP measured using motoring dynamometer showed reduction in power consumption across the engine speed. With higher flow rate and flow velocities across the cylinder head combined with lower coolant temperature inside the cylinder head, the knock resistance of the engine is improved significantly. Spark ignition timing sweep using RON 95 fuel has also shown significant spark advance potentials across the engine speed. The positive test results obtained so far have proven that the proposed simplified engine split cooling has a big potential to meet the demands of future engines.