Emission Performance Of Disel Engine And Smoke Diffusion In Antarctica

Several scientific exploration activities such as ice core survey and astronomical observation have been conducted at the research station in the Antarctic Dome A,which is supported by diesel generators.Emissions exhausted from the diesel generators contain a lot of fine particulate matter,which will affect atmospheric transparency near the research station and make astronomical observations worse.In addition,considering the particularity of the Antarctic environment,low temperature and low pressure will increase the amount of fine particulate matter emitted from diesel generators.Meanwhile,the variability of wind direction and speed make the scope affected by exhaust emissions difficult to determine.Therefore,research on the emission performance of diesel engine and the diffused features of diesel smoke in the South Pole have important reference value and guiding significance to the construction of the research station.The emission performance of diesel engine is affected by various factors such as intake pressure,cylinder internal temperature and fuel type.At present,numerous studies on the emission performance of diesel engine under at normal temperatures and pressures have been carried out.However,There has been a lack of research on the emission performance under low temperature and pressure like the Antarctic.Furthermore,the diffused features of diesel smoke in this Antarctic environment is still indistinct.For this purpose,the Antarctic low pressure simulation platform has been designed and built.An experiment measuring the concentration of exhaust emissions while operating under low pressure in the Antarctic has been conducted.Moreover,a research based on Gauss diffusion model and atmospheric diffusion model in conditions of light air have been conducted to study diffusion rule in the Antarctic Dome A.Finally,a scientific long-term average concentration model taking account of joint frequency distribution in both wind direction and speed has been established.It is used to study the range affected by particulate matter emitted by diesel engine under the impact of wind site at Dome A in the Antarctic.In a word,the research contents and related conclusions in this thesis can be summarized as follows:The experimental studies of particulate emissions from diesel engine in the Antarctic has been conducted in this thesis,especially the relationship between the concentration of various component and engine speed,atmospheric pressure and fuel type.This study shows:(a)With atmosphere pressure going down,carbon monoxide concentration will increase,especially there is a rapid increase under low atmosphere pressure.Hydrocarbon concentration in exhaust emissions will decrease first and then increase.Meanwhile,the concentration of Nitrogen oxide decreases and the one of particulate matter increases.(b)With the engine speed increasing,carbon monoxide concentration will increase.Hydrocarbon concentration of exhaust emissions will decrease first and then increase.Meanwhile,the concentration of Nitrogen oxide will decrease.The particulate matter concentration from diesel engine will decrease first and reaches minimum value where the engine speed is 2400 rpm,then increase.Compared with ordinary atmosphere pressure,the relationship between carbon monoxide concentration and engine speed tend to be more visible and explicit under low pressure in the Antarctic.(3)Compared to general diesel fuels,using jet fuel in diesel engine can effectively reduce the concentration of carbon monoxide and particulate matter.On the contrary,Nitrogen oxide concentration is greater than the one using general diesel fuels.Gauss diffusion model and atmospheric diffusion model under conditions with low winds have been established to study fine particulate matter diffused feature at Dome A in the Antarctic.Meanwhile,long-term average concentration model based on meteorological data has been established to study the range affected by particulate matter emitted by diesel engine under the impact of wind site at Dome A in the Antarctic.The study shows:(1)on the condition that wind direction and speed keep unchanged,the affected area to the leeward side is much larger than the one along horizontal and vertical direction.With the increase of wind speed,the affected area tends to be smaller.(2)On the condition that wind speed is very small even calm,the diffusion of particulate matter along all directions tends to be more uniform.Smoke plume presents a slender structure and lean to the leeward side.The concentration of particulate matter is the largest at the centerline of the plume and decreases toward all direction.(3)Under the combined effect of wind direction and speed in the long term.The maximum area affected by particulate matter is located in the southwest while the minimum one is located in the south direction.In order to reduce the negative effects of fine particulate matter on astronomical observation,it's recommended that the telescopic station can be placed in the south direction of emission source.