| With the increase of car ownership,the environmental pollution caused by cars is becoming more and more serious,and a series of compulsory regulations to reduce the pollution of automobile environment have been introduced in many countries around the world.Reducing fuel emission is one of the important means to reduce automobile environmental pollution,the main measures are oil gas recovery technology utilized in gas station and onboard refueling vehicle recovery(ORVR)technology utilized on vehicle.ORVR technology has high gas recovery efficiency and has become the main objective of reducing fuel emission.At present,the optimization of ORVR system is mainly based on engineering experience that is selecting the best design from multiple discrete design points.The result of this method heavily depends on the selection of design points,and the optimum design usually got missed.In this paper,the multi-objective optimization method is used to optimize the shape of the oil pipe in the ORVR system in order to reduce gas emission and mass of the oil pipe.Since the surrogate model is introduced in the method,the optimum solution could be easily found by using multi-objective optimization algorithm.Firstly,the finite element model of the oil pipe was simulated and validated according to the experiment in literature.The finite element model of the oil pipe which was extract from an actual vehicle was constructed using CFD method and the commercial CFD solver Fluent was used to simulate the refueling progress.The finite elements model was validated by the experiment in the literature,good agreement has been achieved.Secondly,a parameter study of the oil pipe was conducted.It is found that the slant length,the vertical length,the second corner radius and the diameter of the pipe have great influence on the reliability,the timeliness and the weight of the pipe.Thirdly,the surrogate model was built and multi-objective optimization was carried out.Based on the parameter study,four parameters was selected as optimization variables.The design of experiment(DOE)table was created using center composite design(CCD)method.The surrogate model was constructed by polynomial response surface method.Based on the surrogate model,multi-objective optimization was carried out to maximize the liquid volume fraction and minimize the mass of the oil pipe.The optimum design was obtained using weighting method to satisfy all the constraint conditions.Finally,the optimum design was simulated to testify the validity of the optimization method.The result shows that this model improves the possibility of liquid seal,reduces the mass of refueling pipe,and meets the requirements of refueling.This study provides a theoretical basis and new method for the optimal design of tubing,and provides a reference for other designers. |
