The Characteristic Analysis And Improvement Of Internal Heating Constant Volume Combustion Bomb

In the background of the increasingly strict exhaust regulation and big challenge to the traditional internal combustion engine industry,the research group proposes the new idea of “Reaction Controlled Homogeneous Mixture Sequence Auto-Ignition Combustion Mode” from the source of combustion in order to explore the method of increasing thermal efficiency of internal combustion engine in the meantime reducing emissions of noxious substance.For this purpose,system has been improved based on developed constant volume combustion bomb to reduce the heat loss.Fuels such as ethyl alcohol,gasoline,diesel oil and dodecane are burned for verification test to contrast the degree before and after improvement.Firstly,the characteristics of existing incendiary bombs are analyzed.The heat dissipation of the surface is calculated by using the empirical formula for the heat dissipation of the combustion bomb,the power of the heat preservation is designed by the dissipation heat.According to the shape size and mounting parts position of the combustion bomb and the of the on the burning body,the heat preservation parts of the upper,lower cover and surrounding of the combustion bomb are designed and machined.The installation and commissioning of the insulation parts are completed,and the heating power of the heat preservation parts is adjusted according to the test requirement.The voltage regulator is installed between the heat preservation parts and the 220 V power supply,and the input voltage of the insulation parts can be continuously adjustable within the range of 0-220 V.Secondly,by adjusting the power supply voltage of the internal heating wire,the temperature field of the combustion bomb is measured at the input voltage of 30 V,40V,50 V and 60 V respectively.It is concluded that the internal axial height of the combustion bomb is 30-50 mm,and in the region with a radial radius of 30-45 mm,it is the highest temperature field in the body,and the temperature difference in the region is not more than 40 K.And the measurement of temperature field after heat preservation is compared and analyzed with temperature field before heat preservation,it is concluded that uniformity of temperature field is improved greatly after combustion bomb heat preservation,combustion bomb internal temperature gradient decreases obviously and temperature field is more uniform.The average temperature increased by more than 20 K after heat preservation and temperature atmosphere is improved.Then the instantaneous heat release rate and pressure increase rate in cylinder of mixed gas combustion in different combustion modes are studied by adjusting the fuel supply time of several different styles of fuel.The combined gas combustion efficiency is calculated by the pressure change in the cylinder.Through the comparison and analysis of the experimental data,it is concluded that the combustion thermal efficiency of the mixture is significantly higher than that of the heat preservation before the heat preservation.Using the AVL DICOM 400 type five gas analyzer,the combustion exhaust gas of the mixture in the combustion bomb is sampled and tested.After increasing the heat preservation device,the heat loss of the constant volume combustion bomb is reduced.The temperature field in the combustion bomb is more uniform,which can be beneficial to the complete combustion of the fuel.After adding heat preservation,it can reduce the thickness of the quenching rate layer to a certain extent and reduce HC emission.Through the above experimental data analysis,it is found that the decline extent hydrocarbon emissions is largest for the gas mixture of equivalent ratio 0.6 after the heat preservation.Harmful emissions of decane and ethanol fuel mixture has been improved before and after the heat preservation.Overall,there has been a significant improvement in the reduction of emissions from the combustion of the mixture in the combustion before and after the heat preservationDuring the experiment,DMS 500 is used to sample the exhaust gases after combustion,and the emission and particle size distribution of the particles in the exhaust gases after combustion are measured.The test with several kinds of fuel combustion in the incendiary exhaust gas analysis shows that for pure decane and dodecane two fuel combustion exhaust gas are given priority with nuclear modal particles,which are over 95%.In the combustion exhaust gas of diesel and n-heptane ethanol,the particles are mainly composed of accumulated particles,and the proportion of nuclear mode particles are less than 10%.In terms of particulates number,diesel particulate emission is higher than other pure fuels.In general,the improved constant volume combustion bomb can dramatically improve the combustion of mixture and reduce the effect of particle generation and emission.