Influence of coolant temperature on the performance of a four stroke spark ignition engine employing a dual circuit cooling system

Diesel engines have attracted attention because of their higher thermal efficiency and lower carbon dioxide emissions than gasoline engines.  On the other hand, oxides of nitrogen (NOx) and particulate matter (PM) in the exhaust from diesel engines are difficult to be reduced simultaneously because a decrease in one is likely to result in an increase in the other.  In this paper, an attempt has been made to compare the effect of the heat lost to the coolant in the cylinder block, and in the cylinder head with a conventional cooling circuit with corresponding effects in an engine with a dual cooling circuit.  A dual cooling circuit employs separate cooling circuits for the cylinder block, and for the cylinder head.  A single cylinder, four-stroke, water cooled, naturally aspirated spark ignition engine test rig was developed for the purpose.  The influences of the cylinder block and cylinder head temperatures on brake specific fuel consumption (bsfc) and on exhaust emissions were measured.  The results show that raising the temperature of the coolant in the engine block can produce significant improvements in bsfc with a corresponding reduction in the hydrocarbon (HC) emissions.  Similarly, lowering the coolant temperature in the cylinder head can increase the knock limit of the engine with a corresponding reduction in the levels of NOx in the exhaust emissions.   The objective of this investigation was to access the magnitude of the likely benefits of the dual circuit cooling system.Keywords: dual circuit cooling system, spark ignition engine, heat transfer, engine cooling Citation: Rehman A., R. M. Sarviya, S. Dixit, and R. K. Pandey.  Influence of coolant temperature on the performance of a four stroke spark ignition engine employing a dual circuit cooling system.  Agric Eng Int: CIGR Journal, 2010, 12(1): 84-90.&nbsp