Research On Emission Test Cycle And Emission Inventory Of The Diesel Engine For Small Agricultural Machinery

The diesel engine for agricultural machinery with rated power below 36.7k W(diesel engine for small agricultural machinery)has a huge ownership in China.Because of the poor maintenance and the imperfect scrap system,the actual emission level is high.Due to the great difference of operating conditions,the test cycle for the diesel engine emission regulations for non-road mobile machinery can not fully reflect its operating conditions.Constructing a test cycle that reflects the working conditions of the diesel engine and figuring out its emission inventory are of great significance to the control of non-road mobile’s emission.In order to find out the contribution rate of the diesel engine for small agricultural machinery’s emission pollution in China,the diesel engine for typical small agricultural machinery such as tractors and rice transplanters of various power segments with huge ownership and high annual activity levels were selected as the research objects in this thesis.The field operation emission test was carried out based on the portable emission measurement system.The emission data of HC,CO,PM and NO_x during its actual operation was obtained.On this basis,combined with the data of ownership and annual activity level,the emission inventory model was constructed and the emission inventory was estimated.The result shows that the total annual emissions of HC,CO,NO_x and PM of the diesel engine for agricultural machinery are 219,800 tons,1,141,100 tons,301,500 tons and 2,584,400 tons respectively.Among them,the total emissions of the typical diesel engine for small agricultural machinery account for 40.90%,31.71%,40.86%and 39.36%respectively.It is urgent to energy conservation and emission reduction.In order to extract the test cycle that can truly reflect the actual working characteristics of the diesel engine,based on the condition recorder,the actual working conditions of the diesel engine were collected in a full working season.The improved Fuzzy C-means algorithm to cluster the operating conditions data of the diesel engine was used,the number of cluster centers was determined,the weighting coefficients were corresponded and the six-conditions test cycle was constructed.The cluster stability analysis shows that compared with the regulatory test cycle,the six-condition test cycle has a greater coverage of the operating conditions and can better reflect the characteristics of its operating conditions.Finally,the feasible emission control technologies of the diesel engine were analyzed,thechanges of single engine emission level through the emission test were obtained.The emission reduction potential of the diesel engine by using the emission inventory model was analyzed.The result shows that through the upgrading of emission control technologies in 2017,the total annual emissions of CO,HC+NO_x and PM of the diesel engine for the typical small agricultural machinery will be 142,000 tons,436,600 tons and 33,400 tons,and the total annual emission reductions of each pollutant will be 219,800 tons,670,500 tons and 89,800 tons,and the emission reduction rates will be 60.76%,60.56%and 72.90%,respectively.