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Green engineering material choice by using seven-star-cobweb-chart assessment


    121Xing xizhe., Wang lijun. Zheng junhua.

     (Mechanical-Electrical faculty, Hohai university ,Changzhou ,Jiangsu province 213022 ; Huadian Qiqihar Thermal electricity Co Ltd.

    Heilongjiang province 161006)

    Abstract. In this study, we account for factors relate to energy resource and environment during material choice, we

    give each of those factor a representative frame and construct a seven-star- -chart , each factor line be

    compartmentalized into four representative points, connect relative seven points in turn we constructs a green assessment

    polygon, area of the polygon stands for green degree of material . we can choose the best material by calculating the

    area . this method can be named seven-star-cobweb-chart method. According to the method, ,the smaller the area is , the

    better relative material is ; considering distortion situation, we bring forward a series of weighting coefficients qi, then

    we can do by two steps to assess green degree of material:?calculating whole coefficient Q, Q= Пqi , if Q=0, choose

    another material, if not, continue to do step?, ?calculating equivalent area of polygon, choose the

    smallest one as the best material ,in this paper ,we also give the way to calculate the

    equivalent area of the polygon.

    Keywords: Seven-star-cobweb-chart method , Green engineering material,Assessment.

    ?material life. If the material life is long enough ,it is Introduction good. We must restrict to use short life material to fit the Along with getting more and more knowledge about resource quantity and maintain a sustainable industry resourceenergy and environment, people draw more road. and more concerns upon ecology questions and effort to ?Material recycle attribute. If a sort of material life find a sustainable way . in manufacturing field , how to come to a end, then could be recycle ,that will do good to choose green engineering material become an important nature, obviously, different material has different such problem. In order to solve this problem, a simple and attribute, we should judge whether the material has it or feasible method is necessary. In this study , we take the the degree is high or low. choice of engineering material in manufacturing an

    example ,explain some basic factors that should be ?law limitation. In order to protect environment, considered before manufacturing process ,and then prescribe that some materials should not be widely used

    or not be used in future, in industry movement , present a methodseven-star-cobweb-chart assessment

    engineering personnel should observe these law. above method as a solution.

    all, we should know which material is better though

    compare. Seven relative factors of green engineering

    We can judge a material from above seven aspects , material

    these seven aspects construct a reference system ,we call When we choose engineering material, we should take this system seven-star- chart , show in figure 1.based measures as following: on this reference system, in conceptual point of view, we ?material supply attribute. this attribute show the have a universal frameworks. exhaustion time of a sort of engineering material in the nature. The longer exhaustion time is , the better

     material green degree is. Material Supply Attribute

    ?proportion of recycle material. this attribute give us Environment Effect Proportion of Recycle Material the proportion of material component, a material with

    higher recycle proportion is better than a lower one.

    ?Environment effect. When a material is used, it will do Energy Consume Level Material Recycle Attribute harm in some degree to environment by releasing

    poisonous gassolid particulate or liquid , effect from Law limitation Material life these castoff should be assessed to ascertain whether

    the material is suit for environment. ?Energy consume level. During the material life, it Figure 1 seven-star chart must cost energy whether in its smelting or in its

    manufacturing process, Energy consume level is a

    important factor ,we all expect the level become lower

    and lower.

    Seven-star-cobweb-chart assessment method area of different assessment polygon to judge which In order to obtain a quantitative assessment, woe also material is best in given groups. have necessary to compartmentalize those seven factors, Using this method ,one important thing is that seven as a result ,we give the degrees as the following table 1. aspect of factors of green degree must be known

    beforehand , that means , some investigations and material supply A-Exhaustion beyond 100 years

    practical data are necessary. Attribute B- Exhaustion between 51-100 years

    C- Exhaustion between 25-50 years In figure 2, (a) and (b) illustrate the seven-star-table of D-Exhaustion within 25 years two different materials , different green attributes of Proportion of A-All made by recycle material each material are shown. Recycle B- Proportion of recycle material Material Supply Attribute Material bigger than50%

     C- Proportion of recycle material less Environment Effect Proportion of Recycle Material than50%

    D-All made by crude material

    Environment A-Environment effect factor less than Energy Consume Level Effect 25 Material Recycle Attribute

     B- Environment effect factor between

    25-50 Law limitation Material Life C- Environment effect factor between

    50 - 75

     D-Environment effect factor bigger

    than 75 a Material A- Material Energy consume level less

     Energy than 50MJ/kg Material Supply Attribute Consume B- Material Energy consume level

    Level between 50 - 99MJ/kg Environment Effect Proportion of Recycle material C- Material Energy consume level

    between 100 - 200MJ/kg

    D-Material Energy consume level

    Energy Consume Level bigger than 200MJ/kg Material Recycle Attribute A-has no life limitation

    Material life B-Degenerate slowly in using

    Law Limitation Material Life C- Degenerate in middling speed in


    D-Degenerate quickly in using Material A-Recycle thoroughly b Recycle B- Recycle beyond 50%

    Attribute C- Recycle within 50% Figure 2 Seven-star- chart of two different material

     D- Recycle nothing When we calculate the area of a green assessment polygon, a situation may take place : just like shown in Law limitation A-friendly to environment figure 2 (b), if a factor degree is too bad such as marked B-has no limitation by law D, then the relative point is far from the intersection , C-limited by law in future even other factors points is near to the intersection, D- limited by law currently even the area of this polygon is small, the material is also

    not be acceptable, for one factor is bad enough ,it

    effect the whole .we called this phenomenon Table 1 degrees of seven factors assessment distortion.

     To solve the distortion, we cite a series of weighting

    coefficient, for example , we regulate weighting In above table, we classify those seven factors. obviously, coefficient of A is 1,while D is 0, B is 0.67,C is A means well while D is bad . we connect each of seven 0.33 ,then we can get a whole coefficient Q: factor like figure 2, we get an intersection, then divide

    each line equably for three parts , four points come Q= Пqii=1,2,7 qi is weighting coefficient of forth , from the intersection to a factor frame ,we marks each factor.If Q=0, then exclude this material ,if Q? ABC and Dafter that ,every material could find a 0 ,we also calculate the area of green assessment point that stand for an aspect of green Attribute of polygon , now, the area is a equivalent area ,marked S: material. We connect those points in turn , then we get a S=?q? s, i=1,2,7 , by comparing S, we assess polygon ,shown in figure 2. area of this polygon could ii

    green degree of materials. be used as a assessment standard. We can calculate the

     ?Application of proportion factor avoids the dangers Material Supply Attribute


    Environment Effect ?Accuracy of seven-star-cobweb-chart assessment Proportion of Recycle material method relate to whether production practice is

    abundant .

    Energy Consume level ?Life cycle assessment can be used during this seven-Material Recycle Attribute star-cobweb-chart assessment process.

    Law Limitation Material life References

    1. T.E.Graedel,B,R.Allenby, Industrial Ecology ,Second Figure 3 Seven-star-cobweb chart with weighting Edition ,Pearson Education Asia Limited . 2003 coefficient

    2. Deng nansheng, Wang xiaobing, Life Cycle Shown as figure 3, broken lines construct a cobweb, Assessment, Chemical Industry Press, Beijing, 2003. we called this table Seven-star-cobweb chart, if a 3. Zhu qinghua , Geng yong, Industry Ecology Design , factor beyond the cobweb scope ,we can confirm that the

    Chemical Industry Press, Beijing, 2004. material could not be acceptable .

     In all ,we assess green degree of materials by two steps:

    ?calculating whole coefficient Q, if Q=0, choose another material, if not, do next step ?calculating equivalent area of polygon, choose the smaller. Conclusions and discussions

    ?Using seven-star-cobweb-chart method to assess

    engineering material green degree is simple and feasible,

    the final result .

* Supported by HHU junior teacher training foundation , HHUC 04-B002-01 Science& technology innovation


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