Performance Study Of Ammonia-DME Dual Fuel Engine

In order to solve CO₂emissions problem and respond to the carbon peaking and carbon neutrality goals,the engine industry at home and abroad is particularly concerned about the use of clean energy.Among them,ammonia has attracted attention due to its advantages of zero-carbon combustion,easy production and low cost.However,its nonflammable characteristics and low calorific value make it difficult to achieve a high level of engine performance,which makes it necessary to explore new combustion technologies to be applied to engine combustion.The use of pilot fuel for dual-fuel combustion is a potentially effective means to maximize its power performance and economic performance.Therefore,this article will mainly study the ammonia-DME dual fuel engine with DME as the ignition fuel and direct injection of liquid ammonia and DME mixed fuel in the cylinder.By analyzing different control parameters,the effects of DME ratio,compression ratio,injection timing,intake temperature and global equivalence ratio on dynamic performance and economic performance are studied.The power performance index is determined as the brake power,and the economic performance index is the indicated thermal efficiency.In the process of model construction,the 6K diesel/natural gas dual fuel engine is selected as the basic model for reference,and the simulation model of the engine is constructed and verified in GT-Power.The selected operating conditions are 100%load,1800r/min;75%load,1638r/min;50%load,1440r/min;25%load,1134r/min under the original propulsion characteristics.the basic structure is retained in the simulation model,and the boundary conditions are changed and the DME fuel library is established.Then four different speeds are selected as the experimental group,and each control parameter is changed to study its influence on the power performance and economic performance of the engine.Through the DOE experimental design,the influence of each control parameter on the engine power performance and economic performance is considered together.According to the above research,the other four control parameters are analyzed as the independent variable when the DME ratio was 50%.The main effect of each control parameter alone and the interaction effect of their double combinations are analyzed.Then,acocording to the results of analysis,the influence of each double combinations on the response surface of the three-dimensional space is analyzed.The GA genetic algorithm is used to maximize the brake power and the indicated thermal efficiency and find the set value of each parameter that can maximize the response value at different speeds,so as to determine the control parameter design that can optimize the power performance and economic performance of the ammonia-DME dual fuel engine.The results show that when the global equivalence ratio is kept at 0.7,the compression ratio is greater than 19,the injection timing is in the range of-11.7 to-15.4°CA ATDC,and the intake temperature reaches the maximum of 333 K,therefore the effective power and the indicated thermal efficiency are maintained at the highest level at each speed.