Research On The Influence Of Coolant And Lubricant Temperature On Internal Combustion Engine Performance

The increasingly stringent internal combustion engines emissions regulations,has led to the progressively more importance to the engine efficiency optimization.In this context,the experimental methodologies to perform and analyze the energy flow show as a key issue to evaluate the potential of different engine strategies aimed at the consumption optimization and the improvement paths identification.This works deals with the complete description of an experimental energy flow tool,including the comprehensive description of the specific designed experimental installation used to the determination of each energy term and the method in each energy term calculation.Then a study of the influence of coolant temperature on internal combustion engine performance parameters was carried out.After tested the load characteristics about each energy term at different coolant temperature,I drew the chart of corresponding energy distribution proportion and the energy curve with the change of coolant temperature and analyzed the related rules.The comparison and analysis results suggested that economy performance of engine is improved with the increase of coolant temperature,while the friction and pumping loss is decreased with the rise of coolant temperature.When engine coolant temperature is too high or low,indicated thermal efficiency of engine is decreased.When coolant temperature is increased,temperature and pressure of in-cylinder mixture increase,the ignition delay period is shortened with the advance of ignition point,and main combustion period is shortened.It leads to more heat release at the top dead center and the curve shape of heat release rate under middle and high loads is mainly affected by ignition timing.Under low load,the high-pressure cyclic thermal efficiency is higher with higher coolant temperature.In terms of emissions,the source emission of carbon monoxide mainly has a linear relationship with excess air coefficient.The source emission of hydrocarbon is mainly influenced by combustion efficiency and wall quenching effect.With lower coolant and lubricant temperature,the frequency of wall quenching effect is higher and more source emissions of hydrocarbon are produced.The temperature of engine coolant has obvious influence on the source emission of nitrogen dioxide.Moreover,the concentration of nitrogen dioxide is higher with the advance of 50%combustion position.With the increase of load,the proportion of coolant loss is decreased while the proportion of effective work is increased,because the energy of coolant is transferred to effective work.On the basis of this,it is conducive to improve engine economy performance by properly increasing engine load.The proportion of exhaust energy is almost equivalent to that of effective work so it is significant to take effective action on waste heat recovery.In addition,the engine fuel consumption under middle and high loads can be improved by proper increase of coolant temperature.