Material Efficiency Of The Key Recovery Technologies Of End-of-life Vehicles

The annual number of end-of-life vehicles(ELVs)in China is approximately 7 million,which is equal to that of the entire European Union.This figure is estimated to reach 10 million by 2020.Given the limited natural resources in China,ELVs can bring over 10 million tons of material resources to this country.Most of these materials comprise such products as engines,transmission boxes,and other high-value components.However,the recovery of ELVs in China still faces several problems.For example,the classification of the ELVs materials is unreasonable,the process of dismantling ELVs is difficult,and the dismantling and shredding residues are difficult to handle.These problems significantly restrict the sustainable development of the ELVs industry in China.This study selects ELVs as the research object.Material efficiency will be improved through key technological research to develop a sustainable design.The recovery of ELVs will meet the existing regulations and economic demands,as well as enhance the environmental benefits.Dr.J.Allwood of Cambridge University originally defined material efficiency as providing material services with limited material production and processing.The enterprise is considered the main carrier of material efficiency and earning profit is its natural goal.Thus,this study simultaneously considers the environment and economy.Moreover,this research redefines material efficiency as providing material services with limited material production and processing,as well as providing enterprises with a substantially conducive environment for gaining profit.Accordingly,this study proposes an ELVs recovery evaluation system by considering material efficiency.It clarified the significance of the key technologies of ELVs recovery to improve material efficiency.Moreover,material efficiency will be improved by developing a sustainable design,extensive dismantling scenario,and energy recovery.First,this study presented green modular design and life cycle assessment to address the problem of having an unreasonable classification of the ELVs materials.The ELVs materials were used as the case study.The economic and environmental factors were selected as the similarity indexes.The DSM-MDL-GGA method in green modular design was used to divide the modules and generated new clustering modules.The materials in the same module have considerable similarity after clustering.Consequently,ELVs enterprises can classify materials based on this result,thereby overcoming the traditional classification defect,which only depends on the material‘s economy while ignoring its environmental attributes.In addition,clustering results showed that certain materials,such as PVC,should be reduced in automobile products based on the subtractive idea.In the case of engine research,this study used the input and output data of China as the basic data,and analyzed energy consumption and emission under three different strategies,namely,prototype production,light-weighting,and remanufacturing.Results showed that the performance of the ?light-weighting + remanufacturing? strategy is the best in terms of environmental influence.Results of the sensitivity analysis showed that the ?steel,iron,and casting? industry is the most sensitive factor among all the input factors in the optimal strategy.This result demonstrated that light-weighting technology can improve material efficiency.Second,the unreasonable problem of the ELVs dismantling process necessitated the establishment of five different dismantling scenarios to determine the reasonable dismantling depth.These five scenarios were analyzed through the evaluation model of the ELVs economy and environmental attributes for material efficiency.In the economic analysis,an economic model that contains costs,sales,and profit was developed.The fuzzy analytic hierarchy process method was used to determine the weights of each factor.Thereafter,the profit in each scenario was obtained.In the environmental analysis,the GREET model was used to calculate the energy consumption and emission.After performing a comprehensive evaluation,the ?environmental pretreatment + five + assemblies + internal and external components + others? scenario was selected as the optimization program.Accordingly,the ?manual dismantling + mechanized dismantling,shredding,sorting? model was proposed as the future of China‘s ELVs dismantling model based on the original ?manual dismantling + mechanical dismantling? model.This condition could be the theoretical basis to determine the optimum dismantling depth,avoid the arbitrariness and destructiveness of the dismantling process,and improve the dismantling efficiency and reusability of the parts.Lastly,plastic bumper was used as the research object to address the issue of dismantling and shredding the residue of ELVs.The pyrolysis method was adopted to deal with this problem.The pyrolysis reaction mechanism and kinetic characteristics were likewise investigated.The pyrolysis experiment verified the environmental hazard of bumper coating.Result of the bumper particle thermogravity showed that the activation energy of ?PP + EPDM? was 236.91kj/mol,and the optimum cracking temperature was 600°C.The char after pyrolysis was merely 3.17wt%.This result verified that the pyrolysis can be used to deal with the dismantling and shredding residue to meet the 95% recovery target.This condition provides a theoretical basis to solve the difficult problem of dismantling and shredding the ELVs residue,as well as improving material efficiency.The results of this study have important theoretical and practical values for effectively improving the efficiency of materials,as well as efficiently and reasonably dealing with ELV products.The methods and main conclusions of this study have theoretical and practical references for similar studies of other mechanical and electrical products.