| As the power source fuel of internal combustion engines,oil is a non-renewable energy,with the growth of energy demand and continuous exploitation,oil reserves are in jeopardy,and exploring alternative energy sources to develop oil has become a key way to solve the energy crisis.Vegetable oils are renewable and one of the promising diesel alternatives.However,vegetable oil is highly viscous and cannot be used directly on internal combustion engines.Taking advantage of the characteristics of vegetable oil soluble in alcohol fuel,adding alcohol fuel to the mixed fuel of vegetable oil and diesel fuel can effectively reduce the viscosity of fuel.In this paper,four kinds of diesel/castor oil/n-butanol/ethanol mixed fuels(DC80B10E10,DC80B20,DC60B20E20 and DC60B40)were prepared by fuel blending method.In this paper,the pure diesel(D100)is used as a reference.The effects of different EGR rates,injection parameters on engine combustion and emission characteristics in a high-pressure common rail four-cylinder diesel engine were investigated.(1)When alcohol fuel was added to the mixed fuel of vegetable oil and diesel,the mixture had higher oxygen content and lower viscosity,cetane number and low calorific value.The density and surface tension change little,and the physical and chemical properties of the mixed fuel are close to diesel.(2)Under the same load conditions,with the increase of EGR rate,the hysteresis period of the five fuels increased slightly,the peak pressure increase rate and heat release rate of cylinder pressure,cylinder temperature,pressure increase rate and heat release rate in the main pre-injection stage all showed a downward trend,the effective fuel consumption rate increased slightly,the effective thermal efficiency decreased,the NO_x emission decreased significantly,and the particulate matter emission increased.(3)With the increase of PIT,the maximum pressure and maximum temperature in the cylinder have an upward trend;The peak heat release rate in the pre-spray stage decreases,and the phase of the peak occurrence is advanced,and the peak heat release rate in the main spray stage increases.The phase of the pressure rise rate change in the pre-spray stage is advanced,but it has little effect on the peak pressure increase rate in the main pre-spray stage.With the increase of PIQ,the peak pressure and cylinder temperature increase;The peak heat release rate shows a tendency of higher and then lower,that is,the peak heat release rate in the pre-spray stage increases,and the peak heat release rate in the main spray stage decreases.The peak pressure increase rate in the pre-spray stage is increased,and the pressure increase rate in the main spray stage does not change much.With the increase of PIT and PIQ,the effective fuel consumption rate of the five fuels increased and the effective thermal efficiency decreased;NO_x emissions decrease and particulate matter emissions increase. |
PDF Full Text Request