that it will bring the product design to a new stage, which can design the energy-saving products and manufacturing systems. In order to reduce the energy ...
Integrating Energy-saving Concept into General Product Design Hua Li, Hong-chao Zhang, John Carrell Derrick Tate Dept. of Industrial Engineering Dept. of Mechanical Engineering Texas Tech University, 2500 Broadway, Lubbock, TX 79409 hong-chao.zhanggttu.edu, (806) 742-4853 Abstract Currently, Energy and Environmental issues are worldwide concerns. Energy savings is also without doubt the most effective strategy for environmental protection. This paper introduces a new general product design method. Our research effort will be directed towards the following three primary objectives: (1) investigating all the aspects related to energy-saving issues throughout the entire product life cycle; (2) developing a mathematical model (called Energy Factor) to calculate the products' energy consumption throughout the entire life cycle; (3) establishing the theoretical frame of the new innovative product design method. In this innovative method, the energy-saving concept will be applied at the first step of product life cycle, i.e. product design. And we believe that it will bring the product design to a new stage, which can design the energy-saving products and manufacturing systems. In order to reduce the energy consumption throughout the entire product life cycle (from cradle to grave), this design method is based on axiomatic design theory, and integrates design unit and energy factor concepts. In this paper, the theory frame will be described in detail, and the new concept called energy factor will be introduced briefly.
product. From this point of view, we think the best way to solve the energy-saving problem is to consider all of the products' energy consumption information at the very beginning of product design. So the product design method becomes very important here. Unfortunately, there is not a well-developed design method which can be used to design an energy-saving product or manufacturing system. There is lack of fundamental theory to support the general energysaving product design and analyze the product's entire life cycle energy consumption information. Therefore, it is important to develop a new innovative design method with an aim to consider the energy-saving issue throughout the entire life cycle of general products or manufacturing system. Definition In our new design method, there are three important concepts: axiomatic design, design unit, and energy factor. The first new concept we propose in the research project is called Design Unit (DU), which is defined as a new method to describe product design information related with energy consumption throughout the entire product's life cycle. It consists of five elements, which can be expressed as follows: DU=
Where, Introduction --- Is the Identification Number of the DU, and ID As the world's population and standard of living increases, the demand for energy consequently increases as provides a one-to-one correspondence with each DU. FR --- Is Functional Requirements, which is a minimum well. Governments worldwide are working to meet this challenge including developing substitute energies, exploring set of independent requirements that completely characterize renewable energy resources, and reducing consumption of the functional needs of the product throughout the stages of energy. There are more and more demand for new products manufacturing, utilization and recycle. with the requirements of reducing cost and environmental P --- Is the Process, which contains information related to load. And energy consumption is an important parameter to the manufacturing process, recycle process and utilization characterize any product or process because it carries both method. economic and environmental consequences [1]. Energy I --- Is the energy consumption Information. I consists of efficiency and economic development have an intrinsic and Im, Iu and Ir, which are the energy consumption information mutual relationship. Energy savings is also without doubt the in the stages of manufacturing, usage and recycle most effective strategy for environmental protection. respectively. For one product, each stage will have different Last ten years, in order to satisfy the demand of energy- processes, and each process has its own energy consumption saving, some researches that correlate with energy issue have mathematical model. Through this variable, we want to been done. Xiaoying Zhou and Julie M. Schoenung (2004) summarize the similarities of different models, and describe developed a hybrid environmental impact assessment model, the models using a general function, which we will designate but it was only for computer displays [2]. Eric D. Williams as the energy factor. We will also apply a statistical sensitivity and Yukihiro Sasaki (2003) studied the energy analysis of analysis to determine the relationship among Im, Iu and Ir, personal computers, but they only focused on the end-of-life and establish the priority to be optimized. options which were resell, upgrade, and recycle [3]. However, DP --- Is current Design Parameters, which are the key all of them have some limitations: some of them can not cover variables that characterize the design that satisfies FR. the energy impact throughout the entire product life cycle; Through further classification the factors can be subsome of them only focus on specific product, and the divided into lower levels (shown in Fig. 1), and each alternative technologies which can not be applied to general subassembly will have its own DU. products. Obviously, there are few researches considering the energy issues in the entire life cycle stages for general 335 Int'l Electronics Manufacturing Technology Symposium 1-4244-1336-2/07/$25.00 (02007 IEEE
Product Level
DUl [ID,FR,P,I,DP]
DU*2[ID,FR,P,I,D
DfRPID
...[. -
DU
=[ID,FR,P,I,DP]
Subassemblies
Figure 1. Design Unit Decomposition Hierarchy Energy Factor is a new and significant concept we propose in the whole research project. Instead of calculating the energy consumption of some specific products, we believe there will have a general mathematical model which can be applied on all kinds of products, and we call the model as Energy Factor. It is defined as a variable coefficient mathematical model for calculating product or subassembly energy consumption during its life cycle. It is a general mathematical model to calculate or estimate product energy consumption in its entire life cycle. To explore the Energy Factor is the most important part in further research work. Axiomatic design theory, which is well developed and provides a logical path for product development, will become a very important standard and the theory frame in our design method. Through axiomatic design concept, there is a design matrix A will be utilized to describe the relationship between FR and DP as follows: Ai =aFR, {FR}=[A]{DP} while I/DPj In axiomatic design theory, when the design matrix A is a (upper or lower) triangular or diagonal matrix, the product design will be accepted. In our new method, besides to improve the design matrix, we add some new criteria in terms of energy-saving to make sure the outcome of our new method is energy-saving product. Methodology In order to fulfill our research objectives, theoretical analysis, statistical analysis, and experimental validation will be used to explore an innovative product design methodology for energy-saving. To make an energy-saving product or manufacturing system, the best way is to integrate energysaving concept into the entire product design procedures. Based on a comprehensive analysis of regular product design procedures, we try to extract the design information that correlates with energy consumption, itemize and quantify the information, and eventually build up mathematical models for final optimization. Based on the well-developed Axiomatic Design theory, we integrate the energy-saving concept into it, and establish the general theoretical frame of the proposed design method. In the new innovative product design method, there are ten steps for improving an existing product (shown in Fig. 2), and six steps for designing a new product (shown in Fig. 3). Actually, the procedures for designing a new product can be considered as a part of the procedures for improving an
existing product. The illustration of each design procedure for improving an existing product is described as below:
Figure 2. Design Procedures for improving an existed product (1) Step 1 (Modularity analysis): Once we got an existing product, modularity analysis will be used to divide the product into different modules based on the modular design theory. (2) Step 2 (Axiomatic design theory): After getting the modules of the product, we can use axiomatic design theory to analyze the different modules, find the detail function requirements and design parameters, and build the design matrices. (3) Step 3 (Lower level energy factor modeling): Based on the FRs and DPs, the lower level energy factors can be developed to calculate the energy consumption. (4) Step 4 (Product LCA & Rank of stages and parts): Product life cycle assessment will be done to compare the energy consumption information of the product in different stages. Though analyzing the energy consumption information using sensitivity analysis or fuzzy logic system, the rank for different parts and different stages can be found in terms of the importance to energy-saving. After this step, we can get all the information needed in design unit, and then the completed DUs for different parts can be finished. (5) Step 5&6 (New concept generation & new configuration generation): Based on the information in design unit, designers can begin to generate new concepts and configurations to optimize the existing product. The sequence of optimization will be same as the rank we get in step 4. (6) Step 7 (Axiomatic design theory): The new configurations will be analyzed using axiomatic design theory. If the new design matrices are qualified for an uncoupled or decoupled design, designers can go to next step; otherwise, designers have to return to step 5. (7) Step 8 (Energy factor modeling): The energy consumption information for new configuration will be calculated using energy factor models. If the energy consumed in new configurations is less than the existing product, designers can go to next step; otherwise designers have to go back to step 5 to generator new concept. (8) Step 9 (Life cycle assessment): Life cycle assessment will be applied to the new configurations. If the results become better, designers can go to next step; otherwise, designers have to go back to step 5 to generator new concept. (9) Step 10 (Detail Design): Detail design can be done based on the new configurations in this step, and then a new product will be finished based on the existing product, which will have better energy-saving characteristic.
The design procedures for designing a new product show in the Figure 3. As we described above, to design a new energy-saving product, the input becomes new customer needs, and the following steps are same with the corresponding steps in the procedures of improving an existed product.
Figure 3. Design Procedures for designing a new product
material will also cause a very big part of energy consumption, so we decide to involve the material selection into the new product design method, which will make the new design method more practical. Ashby, M. F. has done very well research about the material selection in mechanical design, and after properly modification we will apply the existing results into the new product design method. As above, developing the Energy Factor is sort of integrating existing research results into a new general mathematical model. The modeling of Energy Factor will start with some specific electronic products which are easily analyzed. We are now analyzing a typical product (i.e. hair dryer) to get the actual design information, and the product's energy consumption models based on its energy flow system (shown in Figure 4) will be developed. Then, by analyzing more and more products, we will improve the preliminary model of Energy Factor and get the final result. Enerfg inpu fi6eL 9lectficitY ~d steam
As the core role is our research project, how to model the energy factor becomes the most significant part. First, we Ener conversion L have decided which information would be considered in the r~~~~~~~ FfeduLtiniil IEneruti]iaipn Ene~utThz^tis Eiiinutisztr25L energy factor. In the manufacturing stage, the energy Eneyti1ztDx _"_ I consumed in raw materials, assembly, and manufacturing .|-Rt wtu" 11I processes will be considered. In the usage stage, the energy A i~4 :vMItrg Ue Rev ~W-fe- -1- EIornment consumption used for the product can be approximately considered as the mean of the minimum and maximum power recyele zey1 reyle _ eI consumption, and we try to predict the lifespan of the product's components using Weibull distribution. Here I I EnetresvevI I______ ____ Weibull distribution will play a key role in developing Energy Factor, which is a continuous probability distribution with the Environmeft probability density function. To estimate the energy 4. Product Energy Flow Figure consumption in usage stage, to obtain the life span of each component is significant. And Weibull distribution, which includes the most common distribution usually associated Conclusions with a life cycle including the exponential and the normal This research project has significant potential economic distribution, is a classical and widely used method to predict and social impact. Despite the significance of energy savings, the failure time of component. The Weibull distribution is no research has been conducted in the identification of used to model the failure rates since its parameters are both systematic ways to make energy-saving products and systems. easy to estimate and such parameters can easily accommodate From this point of view, the new design method especially the a rising (or falling) force of mortality. In the end-of-life stage, energy factor concept is very significant. By using the general reuse and recycle will be considered respectively. Since reuse methodology, we can also be able to develop a platform for and recycle of product are well studied, we can directly use further energy saving product research. Industry will be able the existing research results in developing the Energy Factor. to use the product design analysis model to improve their In the end-of-life stage, we try to separate it into recycle and energy efficiency and use the integrated design support reuse, and energy consumed in both ways will be considered. system as a powerful tool for their new energy saving product All the data we collected and used in the research project is designs. It is also expected that through improved product from the previous research results, verifiable records energy efficiency, this project will help to improve energy published by government, and the results calculated by sustainability of the nation and the world, in addition to ourselves. maintain the harmony between human beings and nature. "We Since material is very important to a product, it will decide do not inhibit the earth from our parents; we borrow it from most of the product's characteristics. Different materials also our children," with this old proverb we summarize the mean different manufacturing processes. Meanwhile, design underlying objective of this project. is the process of translating a new idea or a market need into the detailed information from which a product can be Acknowledgments The pilot study of this research is supported by Growing manufactured. Each of its stages requires decisions about the materials of which the product is to be made and the process Graduate Program in Texas Tech University. The authors also for making it. Normally, the choice of material is dictated by would like to acknowledge the contributions of everyone in the design [4]. And to mine raw material and process the Texas Tech Advanced Manufacturing Laboratory.
References 1. Han P. Bao, and Harpreet S. Multani, "Energy-Based Life Cycle Assessment of Industrial Products", Proceedings of the 2007 IEEE International Symposium on Electronics & the Environment, pp. 123-127. 2. X. Y. Zhou, and J. M. Schoenung, "Development of a hybrid environmental impact assessment model: a case study on computer displays", Proceedings of the 2004 IEEE International Symposium on Electronics & the Environment, pp. 91-96. 3. E. D. Williams, and Y. Sasaki, "Energy analysis of end-oflife options for personal computers: resell, upgrade, recycle", 2003 IEEE International Symposium on Electronics & the Environment, pp. 187-192. 4. Ashby, M.F. Materials Selection in Mechanical Design, Pergamon Press (Burlington, 2005), pp. 1-9.
