Effects Of Fuel Properties On Performance And Emissions Of DI Diesel

Thesis title:Effects of Fuel Properties on Performance and Emissions of DI Diesel EngineMaster's candidate:Wang LiqiSupervisor:Prof. Sun WanchenTo face the pressure of aggravation of energy shortage and environmental pollution, using a clean alternative fuel is one of the valid solutions in the internal combustion engine development. Many countries are energetically developing oil alternative fuels for vehicle. The study of the alternative fuels has caused experts' universal attention both at home and broad. They focused on the application of the fuel blends ratio of clean alternative fuels and fossil fuels to improve aspects of physical and chemical properties, thus can achieve the object of improving combustion and reduce emission of the engine. Physical and chemical properties of fuels are essential to the combustion, emission and performance. Also, compared to the traditional engine, the combustion boundary condition of modern engine is changing with the application of new technologies on the internal combustion engine which leads to the change of the impact of combustion and emission by the fuel characteristics. We studied the diesel engine performance and emission by using the blends fuel with different chemical properties made by natural gas to liquids fuel (GTL),BTL and diesel with different ratio on a new generation of electronically controlled high pressure common-rail diesel engine. The main tasks of this paper are as follows:1 Establishment of the test-bed. We established CA4DC2-1063 High-pressure common-rail diesel engine test-bed including the designed engine steady state basted on the electric eddy current dynamometer and the testament and control system of increasing torque with constant speed.2 The production of the fuel. We made up blends fuel with different ratio of GTL/diesel and BTL/diesel and analyze their physicochemical properties.3 The experiment was conducted to study the influence of emission for steady state and load-up transient cycles with constant speed which caused by the different properties of biodiesel/diesel blends fuels. Test results show that there is a good inhibitory effect of extinction FSN and CO on biodiesel compared with the conventional diesel. With the increasing of BTL blends ratio, CO emissions and extinction FSN reduced. The blends fuel with lager ratio has inhibitory effect on the emission of HC, however, the emission of NOx increased a little because of the oxygen content in the biodiesel fuel. Due to the low calorific value of biodiesel, BTL/diesel blends fuel engine torque and power reduced at the same fuel consumption. For transient cycles, the soot are consistent with the steady state conditions, and when the load-up rate is large, the influence becomes larger. The NOx emission was different from steady state conditions. The NOx concentration reduced with the increasing of blends ratio, and increased with the decreasing of the load-up ratio. The HC concentration decreased with the increasing of blends ratio. For the same kind of fuel, the HC concentration increased when the loda-up ratio increased. There is certain difference of HC emission on steady conditions.4 The experiment was conducted to study the influence of emission, engine performance at steady state and transient cycles caused by the different properties of GTL/diesel blends fuels. Test results show that it can reduce the CO concentration. NOx concentration and extinction FSN with different degree when the GTL blends ratio is increasing. The HC emission is lower when the GTL blends ratio is small, and the HC concentration increased with the increasing of GTL blends ratio. But all the values are lower than the values when using Conventional diesel. It can reduce the fuel consumption effectively and improve the Fuel Economy when using different GTL blends ratio fuels. But in the condition of equal fuel consumption of volume, the engine torque and power is lower. For load-up transient cycles with constant speed, the HC, NOx and Extinction FSN emissions are consistent with the emission performance on steady state conditions. With the load-up rate increasing, the NOx reduction level decreased by using mixture fuels. The CO concentration reduced only on large GTL blends ratio conditions.