Water Cooling System for an Electronic Cabinet
Created by: Harjot Hayer Gaurav Nema Lucy Baker Jeff Olson
Sponsors: Dr. Farrokh Mistree & Emad Samadiani ME 6101: Engineering Design Fall 2006
Executive Summary In an attempt to establish the validity of the augmented design method, a project has been executed that will test as many aspects of the method as possible. The goal of this project is to design a water cooling system for an electronic cabinet. To specifically address this problem, the question for the semester was tweaked to target sustainable thermal systems. By exploring the world of 2020, in a distributed environment, we created a requirements list for our design method. To satisfy these requirements, we augmented the Pahl & Beitz systematic design method. In order to validate some aspect of this method, a series of questions have been posed. To address as many of these questions as possible, project tasks have been established accordingly. We found, from going through our method, that the most desired solution uses a water block in a single phase cycle. Since most of the requirements from the customer have been fulfilled, we realized that the empirical structural and performance validity of the proposed design method. Finally, the strengths and limitations of the project have been discussed, and the future scope has been proposed and to justify the utility of the work, a value analysis, with respect to individual A0 goals and the Team A0 goals, has been done.
Table of Contents 1.0 Framing the Question for the Semester 1.1 Original Question for the Semester 1.2 Tweaked Question for the Semester 2.0 Overview of the Project 2.1 Relation of the Question for the Semester to the Project 2.2 Project Description 2.3 Relation of Project to the World of 2020 3.0 Conception of the Augmented Method 3.1 The World of 2020 3.2 Relation of the World of 2020 to Requirements List 3.3 Requirements List for the Augmented Method 3.4 Relation of Requirements List to Augmented Method 3.5 Augmented Method 4.0 Questions to be Addressed by the Project 4.1 Relation of Augmented Method to Questions to be Addressed in Undertaking the Project 4.2 Questions to be Addressed in Undertaking the Project 4.3 Relation of Questions to be Addressed to Project Tasks 5.0 Project Tasks 5.1 Planning and Clarifying the Tasks 5.2 Conceptual Phase 5.3 Embodiment Phase 5.4 Detail Design 6.0 Evaluation of the Method 6.1 Critical Evaluation of the Augmented Method 6.2 Value/Lessons Learned References Appendix
1.0 Framing the Question for the Semester 1.1 Original Question for the Semester • • •
We imagine a future in which geographically distributed engineers collaboratively develop, build, and test solutions to design-manufacture problems encountered in the product realization process. We recognize that solutions evolve over time. Accordingly, we expect you to build on what has been done before. In this context, we want you to provide a method to support the realization of products for a global marketplace through distributed design and manufacture. Specifically, how should the P&B systematic design method should be personalized and augmented to support the realization of products for a global marketplace in a distributed environment?
1.2 Tweaked Question for the Semester We have modified this question slightly to be more suited for our project: How should the P&B systematic design method should be personalized and augmented to support the realization of sustainable thermal systems for a global marketplace in a distributed environment? Our project requires us to design a water-cooling system for an electronic cabinet. Therefore, we have modified the Q4S to support the realization of “Sustainable Thermal Systems”. To understand the meaning of this phrase we have to first understand the meaning of a concept called sustainability. Sustainability is defined as a characteristic of a process or state that can be maintained indefinitely. According to the definition given in Wikipedia “Sustainability is a systemic concept, relating to the continuity of economic, social, institutional and environmental aspects of human society, as well as the nonhuman environment. It is intended to be a means of configuring civilization and human activity so that society, its members and its economies are able to meet their needs and express their greatest potential in the present, while preserving biodiversity and natural ecosystems, and planning and acting for the ability to maintain these ideals in a very long term.” [24] Thermal systems are the systems that deal with the conversion and transfer of heat and work. Hence the sustainable thermal systems are the thermal systems that are designed for sustainability in particular with respect to the environment and energy. This theme will be particularly evident in the world of 2020.
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2.0 Overview of the Project 2.1 Relation of the Question for the Semester to the Project In an attempt to give us a chance to verify some aspect of our design method, this project has presented us with a realistic problem that can be addressed using design methodology learned from class. Other than instinctual observations such as: does the flow diagram make sense, does the final product fulfill enough customer wants, etc, some effort has to be made to verify the method systematically. Therefore, the validation square will be used to confirm that the modifications that were made were beneficial for the design of a global product with the world of 2020 and a distributed environment in mind. The validation square is a 4-step procedure that works by “building confidence in its usefulness with respect to a purpose.” The 4 phases consist of: theoretical structural validity, empirical structural validity, empirical performance validity, and theoretical performance validity.
Figure 1.1: Validation Square The project specifically relates to the second and third quadrant of the validation square, the empirical structural validity and empirical performance validity. To validate these portions of the validation square, an example problem must be chosen to test the intended application of tools/ methods within their respective ranges. In this case, the design project will be the example used to test our augmented method. To do so, we have established a set of questions that must be addressed by the project that relate to the augmented method. After that the data can be analyzed to verify whether it supports the claims that were made. The specific steps that will be verified are explained in the section labeled “Project Tasks.”
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2.2 Project Description The project that has been posed for validation is to design a water-cooling system for an electronic cabinet. “The students are expected to use the systematic design method of Pahl and Beitz to design a system to circulate the water through the cabinet and chips in order to maintain the chip temperatures below 85 °C.” The main aspects of design that will be stressed are ensuring the manufacturability of the product and that the chip does not exceed a maximum temperature of 85 degrees Celsius. Designing for minimum cost, modularity, mass customization, and robustness, while considering the world of 2020 are also desired. The final product has been constrained due to a number of design specifications that have been given to indicate the dimensions, range for the temperature of the water, and the heat flux and dimensions for the chip. Given: Geometry Cabinet Dimensions in meters: 0.61(width)*1.02(depth)*2(height) Server center dimensions in meters: 0.51(width)*0.71(depth)*0.333(height) Server dimensions in meters: 0.051*0.71*0.333 Chip dimensions in cm: 3*3*0.2 Energy Chip heat flux: 100 watt/cm2 Minimum available chilled water temperature: 5°C Maximum available chilled water temperature: 25°C Kinematics Maximum available chilled water flow rate: 180LPM(0.003m3/s) How the Project Relates to our Team A0 Goals Team A0 Goals: 1. 2. 3. 4.
Learn how to implement and evaluate the design method. Learn how to work efficiently and effectively. Learn how to communicate professionally. Learn how to evaluate our own work.
To accomplish the first goal in the project, the augmented method will be applied to the design of the water-cooling system. Putting the method into practice will help us to identify strengths and weaknesses of the augmentations. Efficiency and effectiveness of our work will be improved through the systematic method, and use of a variety of attention directing and time management tools. Through the project reports, presentations, and group work professional communication skills can improve vastly. We will be evaluating our work throughout the course of this project. Using verification and validation techniques, we will learn how to systematically assess strong points and limitations. Also, working collaboratively could definitely help in industry, and knowledge gained can be used in the non-industrial world as well.
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2.3 Relation of Project to the World of 2020 Many aspects of the project reflect the changing environment of the forthcoming future. For starters, the topic of chip cooling will surely become a more prominent issue in the future. According to Bing Dang, a Graduate Research Assistant in Georgia Tech's School of Electrical and Computer Engineering: As the power density of high-performance integrated circuits increases, cooling the devices has become a more significant concern. Conventional cooling techniques, which depend on heat sinks on the backs of ICs to transfer heat into streams of forced air, will be unable to meet the needs of future power-hungry devices…High temperatures can cause early failure of the devices due to electromigration. By controlling average operating temperature and cooling hot-spots, liquid cooling can enhance reliability of the integrated circuits. People are looking at liquid cooling in all forms to solve the thermal issues affecting advanced integrated circuits, and the goal is to prevent damage to the chips. [25] Other aspects of the project that specifically addresses the world of 2020 are modularity/ mass customization, robustness, and design for manufacturing (DFM). Mass customization is defined as the ability “to customize products quickly for individual customers of for niche markets at a cost, efficiency and speed close to those of mass production, relying on limited forecasts and inventory.” According to The National Academy of Engineering, “the explosion in knowledge sharing, coupled with advances in technology” will result in an increased demand for mass customized products in the near future. Robustness, as defined by Prof. Taguchi is “the capability of a system to function properly despite small environmental changes or noise.” With the amount of undisclosed information regarding future products, and their working environment, robustness will certainly be an important issue. Finally, by understanding the types of manufacturing processes available (i.e., the benefits and downsides to each), reducing tight tolerances, adjusting for less undercuts, and following other guidelines for DFM, design for manufacturing, designers can engineer their products to save money and reduce production time and these factors may be even more significant in the future.
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3.0 Conception of the Augmented Method 3.1 The World of 2020 In a book written by The National Academy of Engineering in an article titled, “The Engineer of 2020: Vision of Engineering in the New Century,” the topic of future advancement, as it pertains to engineering, is discussed [4]. It is the Academy’s opinion that engineers must anticipate advances and prepare for the future to ensure that “engineering remains relevant” as society continually changes. According to the Academy, the following changes may occur by the year 2020: • More older engineers, because the age of the mean population is increasing. • Huge developments in technology, especially in the areas of: nanotechnology, logistics, biotechnology, high-performance computing, the medical field, energy, materials (with characteristics not available today), remarkable light sources, and next-generation computers and tele-communications. • Tightening global linkages, deteriorating infrastructure, and environmental concerns. • Providing housing, water, and health care for a rapidly growing population. • Minority growth contributing to an increasingly diverse talent pool. • A growing need for interdisciplinary and system-based approaches. • Increased demand for “customerization,” a buyer-centric business strategy that combines mass customization with customized marketing. According to the Academy: what the engineering profession must do to change for the future: (1) Agree on an exciting vision for its future; (2) Transform engineering education to help achieve the vision; (3) Build a clear image of the new roles for engineers, including as broad-based technology leaders, in the mind of the public and prospective students who can replenish and improve the talent base of an aging engineering workforce; (4) Accommodate innovative developments from nonengineering fields; and (5) Find ways to focus the energies of the different disciplines of engineering toward common goals. In light of this information, the following are the drivers for our vision of the world of 2020, references for the material are provided at the end: Drivers for the changes that will occur between 2006 and 2020 include energy sources, transportation, communication, computers, manufacturing, the relationship between humans and computers, the workplace, waste handling, and customization of a product. Energy sources will be changing from oil and gas to hydrogen, sun, and wind. The metric is renewability. Energy sources should be infinite and everlasting ideally. The world of 2020 holds hydrogen economies, in which energy will be produced by fuel cells and solar cells. Iceland is already switching entirely to a hydrogen economy. People will have little boxes in their own homes that take in water, split the molecules, and produce Hayer, Baker, Nema, Olson 5
electricity. These changes will also affect transportation and the environment, which will be discussed in later sections. What do new energy sources have to do with the design process? These are new solution possibilities to the function of energy supply in design problems. Transportation will change dramatically in the next fifteen years. Speed is the metric for the way in which it will change. The automation of road traffic will be just starting with the sale of specialty cars that can be programmed to get to a destination without interference from the passenger, but with a manual option in case of emergency. This will eventually lead to generally quicker road transportation because of fewer accidents on the road. Suborbital planes will speed up air transportation considerably, making it possible to bring people halfway across the world in under an hour. This will speed up the design process overall, and will enable more people to be involved in each step because they will be more able to attend meetings or be present to troubleshoot a problem in the field or in an experiment. Major transformations in communication will take place in the near future. The accessibility of people is the metric for these changes. This has always been an issue in the work environment and people will try to minimize this issue as much as possible, although it can never really be solved. Third world countries of today will gain access to new communication tools such as the Internet and cell phones and will be more able to participate in the world economy in 2020. The Internet will be prominent, maybe appearing in airplanes, bathrooms, and vehicles. There will be video capability on cell phones so that people can see each other and show files to facilitate conversations. These advances will speed up the design process because people will be able to work in situations or places they normally would not be able to. They will also lead to a distributed work environment, which will be discussed when talking about changes in the workplace. Computer technology changes every few months, so one can only imagine how different it will be in the year 2020. The metrics for how it changes are speed and capacity to store information. In fifteen years, designers will be able to simulate anything on the computer. This will reduce prototyping costs. Quantum computing is the technology that will make any simulation possible. It can perform some calculations billions of times faster than any silicon-based computer. These tools will thus facilitate the evaluation of solution variants in the conceptual design phase. Manufacturing will be revolutionized with the development of nanotechnology. The metrics for why it will change are speed, quality, and costs. Nanotechnology will make the fabrication of some products possible that no machining process could handle. Only specialty items will probably be made by the year 2020 because of the elementary stage that nanotechnology is in now. Additive manufacturing processes such as stereolithography and selective laser sintering will become commonplace. Manufacturing will be much easier and faster, reducing costs to make some products. The migration from subtractive manufacturing to additive manufacturing will make manufacturing a factor in forming solution variants, embodiment design, and detail design. Manufacturing will have to be considered throughout the design process instead of the current method of coming up with an idea and then trying to figure out how it should be fabricated. Hayer, Baker, Nema, Olson 6
The relationship between humans and computers will be different in 15 years. The metrics are the dependence of humans on computers and the communication between the two. Computers will be more able to do things that humans have traditionally had to do themselves. Because of this, humans will have to rely more on computers in the future. The communication between humans and computers will change from keyboard taps and mouse movements to computer chips in the brain that control computers through brainwaves. Computers will be integrated into every step of the design process performing most tasks except for ideation, communication, and decision making. The workplace will become less and less physical in the next fifteen years. The metric for this change is efficiency. Efficiency is affected by how much time is spent working and how much time is wasted unnecessarily. What activities waste time? Unnecessary meetings, dealing with paper documents, and transportation are all factors. Companies will strive to become paperless, making obsolete the infamous filing cabinet and stacks of paper on desks. Businesses will depend more on the Internet to do work, moving toward virtual workplaces or large private chat rooms on the Internet. Because everything will be done on the computer, people will be able to work at home. This will lead to a distributed work environment because to a virtual workplace, work done in Atlanta, GA or Tokyo, Japan is the same. Location will no longer be important. When forming a design team, options for team members will increase because there is no geographical restriction. More people will be able to give feedback throughout the design process because they will be more connected to the design team in the virtual workplace. Waste handling will improve from an environmental standpoint in the near future. The metric for its improvement is the amount of waste generated. Wastes contribute to ozone depletion, air and water pollution, and global warming. Producers can no longer make goods that give off CFC’s today. In the future, restrictions on what plants can dump into rivers and lakes and let out of their smokestacks will rise in an effort to reduce air and water pollution. Cars will be forced to cut down on emissions to slow the process of global warming. Recycling will become routine and expected so that waste is minimized. Because society will be much more concerned about the entire life cycle of products and their effects on the environment, these concerns will need to be incorporated throughout the design process, from choosing solution variants based on their environmental effects to selecting materials that are biodegradable or are recyclable. Product customization will be more regular in the year 2020. How well a product suits an individual’s needs is the metric for this change. Goods will be made modular so that they can be easily customized for one of many customers. Dell is already trying this out by making the PC “personal again” and Intralox makes separate sprockets, modules, and rods that can be assembled to form a unique plastic conveyor system for each customer. Other companies will soon follow. Mass customization will need to be considered during the conceptual design phase when transforming function structures into solution variants. These solution principles will need to be made as modular as possible to support mass customization. The following table shows each driver with its respective metrics, as well as the corresponding augmentations to the requirements list for the Pahl and Beitz method. The number next to each requirement indicates its location in the requirements list. Hayer, Baker, Nema, Olson 7
3.2 Relation of the World of 2020 to the Augmented Requirements List The changes between now and the year 2020 create new requirements for the Pahl and Beitz method that the authors did not need to consider when they formed the design process. These new requirements are listed below with their respective drivers and metrics. Drivers for 2020 Energy Sources
Metrics Renewability
Transportation
Speed
Communication
Accessibility of People
Computers
Speed and Capacity to Store Information
Manufacturing
Speed, Quality, Costs
Relationship between Humans and Computers
Dependence of Humans on Computers and Communication between the Two
Workplace
Efficiency
Waste Handling
Amount of Waste Generated
Product Customization
How Well a Product Suits an Individual’s Needs
Requirements for Augmented Method 22) Demand: The decision making should be based on the requirements list and technical, environmental, ethical, economical and safety criteria. 19) Demand: Should be suitable for distributed design environment. 11) Demand: Allow for collaborative efforts. 19) Demand: Should be suitable for distributed design environment. 20) Demand: Factor in feedback by all people involved in the design: manufacturers, management, and design team. 23) Demand: Should be compatible with electronic data processing. 24) Demand: Should be able to incorporate advanced design tools like modeling, simulations, prototyping, etc. 32) Demand: Make sure that the product can be manufactured. 23) Demand: Should be compatible with electronic data processing. 24) Demand: Should be able to incorporate advanced design tools like modeling, simulations, prototyping, etc. 7) Demand: Help with time management and scheduling. 18) Wish: Should be able to conform to the company’s documentation policies. 26) Demand: Must take into account team planning and management in design. 22) Demand: The decision making should be based on the requirements list and technical, environmental, ethical, economical and safety criteria. 8) Wish: Should consider masscustomization of the product.
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3.3 Requirements List for Augmented Method Modifications can be seen in italics for those changes that were made for personalization, and underlined for those changes made for augmentation. Requirements List for Augmented Pahl & Beitz Design Process
ME 6101A Changes
D/W
Requirements
W D D D
1 2 3 4
D
5
D D W W D D D W D D
6 7 8 9 10 11 12 13 14 15
W
16
W W
17 18
D D
19 20
W D
21 22
D D
23 24
D
25
D
26
D
27
D
28
D
29
D
30
D D
31 32
D
33
1. The General Process Be applicable at any phase of the design process. Can be used for any discipline in which design is involved. Be straightforward to allow any engineer to use it. Accomplish everything required in a design through a step-by-step process. Should be modular so that it can be used in original, adaptive or variant design. Eliminate bad ideas. Help with time management and scheduling. Should consider mass-customization of the product. Help organize thoughts. Have tools to help designers to complete the steps. Allow for collaborative efforts. Allow for creativity. Be flexible to allow changes/modifications in the method. Allow for revisions and reiteration as necessary. Sequential so that the desired solution can be found systematically. Cost structure should consider outsourcing, international trade etc. Can be easily learned and taught. Should be able to conform to the company's documentation policies Should be suitable for distributed design environment. Factor in feedback by all people involved in the design: manufacturers, management and design team. Take into account quality while designing. The decision making should be based on the requirements list and technical, environmental, ethical, economical and safety criteria. Be compatible with the electronic data processing. Should be able to incorporate advanced design tools like modeling, simulations, prototyping etc. 2. Product Planning and Clarifying the Task Should take into account global market and economic environment. Must take into account team planning and management in design. Make sure that it is known what is desired so that the final design matches the initial expectations. 3. Conceptual Design Should be able to abstract problem statement ("solution neutral problem statement"). Transform the requirements into functions that meet the requirements. Should be able to come up with a principal solution according to the requirement list. 4. Embodiment Design Make the realization of conceptual solution possible. Make sure that the product can be manufactured. 5. Detail Design Ensure that all the documents are accurate and that the products can be manufactured and used after the end of the detail design without having to come back for help from the designer.
Issued on: 11/19/06 Page:1/1 Responsibility Design Team Members Lucy Baker, Harjot Hayer, Gaurav Nema
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3.4 Relation of Augmented Requirements List to Augmented Method Each of our augmented requirements corresponds to modifications in the method. The relationships are shown in the following table.
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3.5 Augmented Pahl and Beitz Method Task Global market, company, global economy
Plan and clarify the task: Analyze the market and company situation. Investigate Global Implication Find and select product ideas (Possible use of ideation tools). Formulate a product proposal. Define the type of design to be used (original, adaptive or variant). Modify the design method according to the specific design type. Schedule the design project/Plan of action (Possible use of 7M&Pand time management tools). Plan the design team structure. Select the appropriate team members (utilize motivational tools). Define the responsibility and allocate the required resources (team contract). Clarify the task. Elaborate the requirement list (Possible use of HOQ).
Requirement list
Information: Adapt the requirement list
Develop the principle solution: Identify essential problems. Establish function structure. Search for working principle and working structures (Possible use of ideation tools). Combine and firm up into concept variants (Classification Scheme/Advanced Decision Matrix). Draft Computer Model Evaluate against technical, economical, environmental/green engineering and ethical criteria (Use of Preliminary Selection DSP and Selection DSP).
Concept (Principal solution)
Develop the construction structure: Preliminary form design, material selection and calculation. (Possible use of simulation and computational modeling tools, e.g., FEA) Select best preliminary layouts. Refine and improve layouts. (Possible use of simulation and computational modeling tools) Evaluate against technical, economical, safety, environmental/green engineering, and manufacturing aspects. Evaluate exportation costs.
Preliminary layout
Define the construction structure: Develop the prototypes for preliminary layout. Eliminate weak spots. Check for errors, disturbing influences and minimum cost. Prepare the preliminary parts list and production and assembly documents.
Definitive layout
Prepare production and operating documents: Elaborate detail drawing and parts list. Investigate locations for fabrication, storage and sale. Complete production, assembly, transport and operating instructions. Check all documents.
Group Feedback Revise Plan of Action Revise Allocation of Tasks
Group Feedback Revise Plan of Action Revise Allocation of Tasks
Group Feedback Revise Plan of Action Revise Allocation of Tasks
Group Feedback Revise Plan of Action Revise Allocation of Tasks
Group Feedback
Product documentation
Solution
Figure 3.1: The Augmented P&B Method Hayer, Baker, Nema, Olson 11
4.0 Questions to be Addressed by the Project 4.1 Relation of Augmented Method to Questions to be Addressed in Undertaking the Project In the previous section we elaborated our augmented method. There were, however, questions that remained that needed to be answered with the completion of the project. These questions are tabulated below with their corresponding step(s) in the augmented method. Question to be Addressed Does the augmented method work? How useful is the resulting design from this method? Are there systematic steps that seem unnecessary? Where should design for manufacturing be placed in the method?
Does the systematic method hinder or support creativity?
Should any more steps or tools be added? Should any steps or tools be moved? Is the method adaptable for the world of 2020?
Is the process conducive to collaborative efforts? Do the augmentations sufficiently address environmental and ethical issues?
Step in Augmented Method All All All Evaluate against technical, economical, environmental/green engineering and ethical criteria (conceptual phase) Evaluate against technical, economical, safety, environmental/green engineering, and manufacturing aspects (embodiment phase) Prepare the preliminary parts list and production and assembly documents Investigate locations for fabrication, storage and sale (embodiment phase) Complete production, assembly, transport and operating instructions (detail phase) Search for working principle and working structures (Possible use of ideation tools). Combine and firm up into concept variants (Classification Scheme/Advanced Decision Matrix) (conceptual phase) All All Mass customization, environmental and ethical issues, teamwork, using computer models and simulations, manufacturing, and workplace efficiency can be implemented in the selection part of the conceptual phase. Group feedback, team structure, plan of action, allocation of tasks Evaluate against technical, economical, environmental/green engineering and ethical criteria (conceptual phase) Hayer, Baker, Nema, Olson 12
Does the method support a distributed design environment and a global marketplace?
Are reiterations of steps easily executed in the process?
Evaluate against technical, economical, safety, environmental/green engineering, and manufacturing aspects (embodiment phase) Many steps for global marketplace have been disregarded from the project tasks to save time. But, to address a distributed design environment, an experiment must be conducted using distributed design (see Plan the Design Team Structure). Group feedback, revise plan of action, revise allocation of tasks, and arrows after each step in the process for reiteration
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4.2 Questions to be Addressed in Undertaking the Project Before beginning the project, the group was curious about specific aspects of our augmented method and how well they would work. The following questions are those that were posed prior to the commencement of the verification. • • • • • • • • • • •
Does the augmented method work? How useful is the resulting design from this method? Are there systematic steps that seem unnecessary? Where should design for manufacturing be placed in the method? Does the systematic method hinder or support creativity? Should any steps or tools be added or moved? Is the process conducive to collaborative efforts? Do the augmentations sufficiently address environmental and ethical issues? Is the method adaptable for the world of 2020? Does the method support a distributed design environment and a global marketplace? Are reiterations of steps easily executed in the process?
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4.3 Relation of Questions to be Addressed to Project Tasks In an attempt to address as many questions that we posed as possible, we carefully selected the project tasks we would complete. To make sure that the augmented method works, we chose project tasks from every phase of the design process. To determine whether there are systematic steps that are unnecessary, we included as many tasks as we thought time would allow. To secure a place for design for manufacturing in the method, we included the evaluation of manufacturing aspects in the embodiment phase as one of our project tasks. To answer the question about creativity, which mostly occurs in the conceptual phase, we added project tasks from the conceptual phase for the ideation of concepts. To address the issue as to whether steps should be moved or added, we have tried to incorporate as many steps in the process as possible, from each phase. Collaborative effort has been addressed in the project tasks through the multiple steps included for group feedback, team structure, plan of action, and the allocation of tasks. Next, environmental and ethical aspects were considered through the incorporation of these criteria in the evaluation process. According to the augmented requirements list, we have added steps in the method. To incorporate many of these ideas, they must be used as design criteria for concept evaluation, so that step has been included. No specific steps have been added to address a distributed design environment and a global marketplace, but an experiment has been planned to check if the method can be used in a distributed design environment. Finally, the ease of reiteration of steps can be analyzed after each phase of the process, since these steps have been included.
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5.0 Project Tasks
Task Global market, company, global economy
Plan and clarify the task: Analyze the market and company situation. Investigate Global Implication Find and select product ideas (Possible use of ideation tools). Formulate a product proposal. Define the type of design to be used (original, adaptive or variant). Å Modify the design method according to the specific design type. Å Schedule the design project/Plan of action (Possible use of 7M&Pand time management tools). Å Plan the design team structure. Å Select the appropriate team members (utilize motivational tools). Define the responsibility and allocate the required resources (Team Contract). Å Clarify the task. Å Elaborate the requirement list (Possible reference to HOQ). Å Group Feedback Revise Plan of Action Revise Allocation of Tasks
Requirement list
Å
Information: Adapt the requirement list
Develop the principle solution: Identify essential problems. Å Establish function structure. Å Search for working principle and working structures (Possible use of ideation tools). Å Combine and firm up into concept variants (Classification Scheme/Advanced Decision Matrix). Å Draft Computer ModelÅ Evaluate against technical, economical, environmental/green engineering and ethical criteria (Use of Preliminary Selection DSP and Selection DSP). Å
Concept (Principal solution)
Develop the construction structure: Preliminary form design, material selection and calculation. (Possible use of simulation and computational modeling tools, e.g., FEA) Å Select best preliminary layouts. Å Refine and improve layouts. (Possible use of simulation and computational modeling tools) Å Evaluate against technical, economical, safety, environmental/green engineering, and manufacturing aspects. Å
Preliminary layout
Define the construction structure: Develop the prototypes for preliminary layout. Eliminate weak spots. Å Check for errors, disturbing influences and minimize cost. Å Prepare the preliminary parts list and production and assembly documents. Å Evaluate exportation costs.
Definitive layout
Prepare production and operating documents: Elaborate detail drawing and parts list. Å Investigate locations for fabrication, storage and sale. Complete production, assembly, transport and operating instructions. Å Check all documents. Å
Group Feedback Revise Plan of Action Revise Allocation of Tasks
Group Feedback Revise Plan of Action Revise Allocation of Tasks
Group Feedback Revise Plan of Action Revise Allocation of Tasks
Å
Å
Å
Å Group Feedback
Product documentation
Solution
Figure 5.1: Steps that will be Verified.
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Red arrows shown in Figure 6 mark the steps that will be incorporated in the design of this project. Some steps pertaining to designing for globalization have been omitted due to time constraints. Considering that there was approximately 2 months to complete this project, we realized that all aspects of our revised method could not be implemented, but most of the other steps, including many augmentations have been included. 5.1 Planning and Clarifying the Task Define the type of design to be used (original, adaptive or variant). Pahl and Beitz define original design as a problem in which “neither the individual sub-functions nor their relationships are generally known”. Creating a function structure is a crucial step in original design. In adaptive design, “the general structure with its assemblies and components is much better known”. Although the solution principle remains the same, the function structure can be modified to meet special demands of the requirements list. Variant design only involves size changes or rearrangement of parts. The solution principle and function structure are unchanged. Different materials or constraints do not cause problems in the design. Since we have to create a function structure and solution variants for this project, our problem is original design. Modify the design method according to the specific design type. Since our project is original design, all steps of the augmented Pahl and Beitz method must be utilized to arrive at a solution. If it were adaptive or variant design, we would be able to skip the conceptual design phase and move on to embodiment and detail design. However, if one portion of a generally adaptive design problem requires original design, the entire augmented method could be used just for that part of the problem. Schedule the design project/Plan of action (Possible use of 7M&P and time management tools). A Gantt chart was prepared to help with scheduling the tasks for the project and defining individual responsibilities. It was helpful because it made it easy to see if our team was falling behind. Also, the Gantt chart kept all the members of the team on track because it specified what tasks were to be done by whom.
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Responsibility
Tasks
Baker, Hayer, Nema, Olson
Presentation Preparation
Baker, Hayer, Nema, Olson
Midterm Report
Baker, Hayer, Nema, Olson
Define the Type of Design
Baker, Hayer, Nema
Modify the Design Method
October
November
December
Phase 1
Hayer, Nema
Schedule/Plan of Action
Baker, Hayer, Nema, Olson
Plan the Design Team Structure
Baker, Hayer, Nema, Olson
Define Responsibility and Allocate Tasks
Baker, Hayer, Nema
Clarify Tasks
Baker, Hayer, Nema, Olson
Elaborate Requirements List
Baker, Hayer, Nema, Olson
Identify the Essential Problem
Phase 2
Baker, Hayer, Nema
Identify Function Structure
Baker, Hayer, Nema
Working Principles and Working Structure
Baker, Hayer, Nema, Olson
Concept Variant
Baker
Draft Computer Model
Baker, Hayer, Nema, Olson
Evaluate Concepts
Baker, Hayer, Nema
Preliminary Form Design
Baker, Hayer, Nema
Refine and Improve Layouts
Phase 3
Baker, Hayer, Nema, Olson
Select Preliminary Layouts
Baker, Hayer, Nema, Olson
Evaluate Preliminary Layouts
Baker, Hayer, Nema
Eliminate Weak Spots/Check For Errors
Baker, Hayer, Nema, Olson
Prepare Preliminary Documents
Baker, Hayer, Nema
Elaborate Detail Drawings and Parts List
Phase 4
Baker, Hayer, Nema
Complete Instructions
Baker, Hayer, Nema, Olson
Check All Documents
Baker, Hayer, Nema, Olson
Prepare Final Report
Baker, Hayer, Nema, Olson
Prepare Final Presentation
Final Submissions
Plan the design team structure. To organize our design team structure, we derived project goals based on each member’s individual goals. To do so, we combined like aspirations and came up with original goals that can be fulfilled by the project. Although this may not specifically address all of the members’ A0 goals, these objectives may help us get closer.
Hayer, Baker, Nema, Olson 18
The first project goal of learning how to implement and evaluate the design method was formed from the combination of Lucy’s desire to be systematic, Gaurav’s aspiration to learn more about teamwork, and Harjot’s curiosity about implementing various design techniques and using the Pahl and Beitz method for any application. Learning how to work efficiently and effectively came from Lucy’s fourth goal and Gaurav wanting to learn how to learn efficiently and effectively and to learn about teamwork and time management skills. The third project goal of improving professional communication was based on Lucy’s need to learn about professional communication and Gaurav’s desire to learn effective technical writing and presentation skills. The final project goal of learning how to evaluate our own work came from Lucy wanting to learn how to evaluate her own work and the team knowing that the project would be an evaluation of its work on the answer to the question for the semester. After combining our goals, we had to be sure that we have the same ethical and moral beliefs. To do this, we talked about cheating and plagiarism before agreeing to work together. We also wanted to ensure that our team members would be on the same page by discussing the distribution of work amongst the group. We agreed that we all wanted full cooperation with each person contributing the same amount and that we wanted to avoid argumentative and dominating behavior. We assessed the skills of each group member to guarantee that even though we would all be contributing the same amount, we would have different skills to contribute. For example, Harjot is excellent at persuasive writing and mediation, ProEngineer, and finite element analysis. Gaurav has heat transfer and finite element analysis experience to offer, and Lucy can program, design in SolidWorks, and has considerable knowledge about additive and subtractive manufacturing processes. Since none of the group members are dominating or reserved, conflicts that arose were easily resolved with compromises. Since the skills of each team member overlap, responsibilities changed throughout the design process. The allocation of tasks within the group was revised after each major step in the design process as shown in the figure of our augmented method. In the planning phase, every team member researched and studied current commercial designs of water-cooling systems. Together we formed a plan of action. In the conceptual and embodiment design phases, responsibilities shifted more towards the skills of each individual. For example, Lucy contributed ideas for solutions and created a model of the final concept in SolidWorks, Gaurav performed heat transfer calculations on potential solutions, and Harjot checked Gaurav’s work and helped make decisions among promising concepts. In the detail design phase, Harjot, Lucy, and Gaurav constructed tables and diagrams and typed the end-of-semester report. Another aspect that we must consider in the design team structure is cultural diversity. Even though our team speaks 7 different languages altogether including English, French, Spanish, German, Punjabi, Sanskrit, and Hindi, the engineering design involved in this project uses universal languages such as mathematics and heat transfer. The cultural differences in our team have only added spice to our design and writing. Also, considering the diversity in our backgrounds, we definitely got perspectives that were less constrained than if we were from the same location.
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Team collaboration occurred mostly through meetings that were scheduled at the beginning of the semester and carried out throughout the course of the semester. See the next section about the team contract for the weekly meeting schedule. We also met on other days of the week when necessary. Meetings occurred in the same room for the most part, but we experimented with a chat room online to make sure that we could design in a distributed environment. Work was a little bit slower and papers had to be split into portions that each person would type so that work could be done simultaneously. Files were then transferred using the file transfer function of the chat room and were compiled afterward. It was noted that individual responsibilities had to be clear in order for the team to design efficiently and effectively in a distributed environment. However, sending links and messages was instantaneous compared to email, which made research quicker. Define the responsibility and allocate the required resources (Team Contract and Motivation tools) Designers and managers forget that the primary factor in how efficient they or their employees are is motivation. If a designer is not working, the design process will not be efficient no matter how structured or systematic it is. There is a human element that is not currently considered in the Pahl and Beitz process that must be added. Motivation tools should be utilized throughout the process. Goals were stated in the planning phase and referred to every day during the course of the design. The other tools listed below were incorporated into daily activities. All group members were made aware of everything on the following list, for some of these things are the individual’s responsibilities. •
Goals [7] o Develop a vision or major goal (It helps to have the end in sight) o Separate a major goal into many smaller goals (How to eat an elephant: one piece at a time) o Get into the habit of finishing what you start (It makes you feel accomplished and more like you are able to complete tasks) o Be willing to take the risk of failure to overcome fear of failure (Thomas Edison: “I have not failed. I’ve just found 10,000 ways that won’t work.”) o Develop goals and challenges for all employees (same as the first bullet) o Short term goals and long term goals according to The One Minute Manager (The author suggests that the employee set short term goals for say, the week, and long term goals for the quarter or year or both. It is related to separating major goals into smaller goals.)
•
Feedback [7] o Find support through friends, acquaintances, and coworkers (It helps to have external reminders of what you are working toward) o Tolerate learning errors by avoiding harsh criticism (goes hand in hand with overcoming the fear of failure) o Provide lots of encouragement (Worker needs to feel like he or she is capable of completing the task) Hayer, Baker, Nema, Olson 20
o Make appreciation part of your repertoire (Lets the employee know that completion not only holds the benefit of the work itself but it also lessens the load of others around him or her) o Develop measurement that shows performance increase (Shows worker that both improvement and slacking are noticed) o Constructive criticism when the employee does something wrong (Related to the risks involved with failure and the fear of failure and facilitates learning) o Progress reports (Makes the employee conscious that the manager will know how much work he or she is doing or not doing) •
Responsibility [7] o Provide employees with input and choice in how they do their work (shows the worker that there is freedom in the tasks) o Encourage responsibility and leadership opportunities within your company (Makes the employee feel important and influential) o Promote job ownership (Makes the worker feel like he or she has power or control over something)
•
Social Interaction [7] o If your employees do routine work add some fun and variety to their routine (Helps the employee have something to look forward to and stimulates the mind in a normally monotonous environment) o Promote social interaction and teamwork between employees (It is good to have people on the same level to identify with each other and help each other) o Discourage harassment: sexual or excessive teasing (Helps employee feel comfortable in the work environment and not dread going to work each day) o Minimize the appearance of a hierarchy within the company (Support bosses and employees dressing the same(suits vs. business casual) and socializing with one another)
•
Side Effects of Hard Work o Day goes faster while working o Lower stress when work is done because there is less of a burden o Better sleep at night o Hard work wards off depression by keeping the mind active and making the employee feel accomplished
Based on the capabilities of each group member, the responsibilities were defined using the Gantt chart. Refer to schedule the design project/plan of action. Team Contract: Team A0 Goals 1. Learn how to implement and evaluate the design method. 2. Learn how to work efficiently and effectively. Hayer, Baker, Nema, Olson 21
3. Learn how to communicate professionally. 4. Learn how to evaluate our own work. Mode of Operation The team met on Thursdays after class to work on the project. This time has been chosen to conform to everyone’s class schedule. Additional meetings were planned depending on necessity and the availability of group members. Tasks were completed according to the Gantt chart of the plan of action. Monday
Tuesday
Wednesday
Thursday
Friday
8:00 9:00 10:00 11:00 12:00 1:00 1:30 3:00 4:00 5:00 6:00
MEET
ME 6101 Lecture Lucy/Harjot in Class Gaurav in Class
Responsibilities 1. Tasks were assigned to team members with relevant strengths and A0 goals. 2. Preferences for certain duties were taken into consideration. Penalties Although no specific penalties would be received, the group as a whole would suffer with substandard work. Individuals would produce inadequate answers to the question for the semester and learning objectives may not have been fulfilled at the end of the semester if we had produced second-rate work. Why this Group will Succeed The members of this team have similar A0 goals and have collaborated to produce a successful validation of the augmented Pahl and Beitz method. The following table is a need-strength matrix for our group:
Hayer, Baker, Nema, Olson 22
Team Strengths
Chip Cooling
Heat Transfer
Fluid Mechanics
X
X
Manufacturability Customer Needs
Computer Model Micro Cooling Systems
X
Solid Modeling
Manufacturing
X X
X
Micro Channels
X
The group possesses considerable computer modeling skills and is experienced in heat transfer and fluid mechanics. These abilities were necessary in designing a water cooling system for an electronic cabinet in the conceptual and embodiment design phases when simulations and calculations were crucial. In addition, all members of this team were willing to work hard to produce quality results. The most important thing contributing to our success is that we all recognized that this project is vital to achieving our A0 learning objectives, and therefore we all strived to do it well. Signatures Lucy Baker_______________________________ Gaurav Nema_____________________________ Harjot Hayer______________________________ Jeff Olson________________________________ Clarify the task. The House of Quality (HOQ) is a design tool, specifically a combination of attention directing tools that can help with product planning and clarification of the task. Quality is beyond just the reduction of defects, it also applies to how well the product fulfills customer needs. QFD, or quality function deployment, is structured product planning. It helps designers specify the wants and needs of customers, and evaluate products based on how well they meet the needs. The House of Quality is a “conceptual map” that allows for interfunctional planning and communications. While working on this assignment, we realized it could be difficult establishing customer needs considering everyone’s preferences are different. A market analysis would have definitely been useful for this, but considering the amount of time we had to work with, an in-depth market analysis was out of the question. To construct the HOQ, the customer wants were weighted based on whether they were demands or wishes, and their relative importance. Another issue in this diagram that we had to consider was that sometimes customer wants are conflicting. Often a compromise must be made, since not every customer desire can be met completely. In this scenario, there must be some “satisfice” made. One example of this can be seen between designing for robustness and minimizing cost. Sometimes in order to make a system robust, features must be added which raise the total cost of the design. In addition, the customer has made requirements for keeping the chips from overheating, but has also stipulated the water must be greater than 5° C.
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It was obvious that the HOQ was a great tool for displaying the relationships between technical aspects and customer needs, but the ranking only shows how well a customer want relates to possible how’s a company may achieve the needs. This must not be confused with a ranking of importance for the customer. Although a how may relate to many customer needs, that does not specifically make it the most important. For instance, although minimizing complexity, by using fewer components, is a “how” that relates to many customer needs, that does not necessarily make it most important. Therefore, to rank the customer wants in order of importance, a prioritization matrix was constructed in a later section. The highest ranked how in the house of quality is to minimize complexity, followed by referencing the design catalog and keeping the water between 5 and 25°C. These how’s stretch across the customer wants the most. The how “water cannot exceed 180L/min” has the lowest ranking because it is only related to keeping the chips from overheating and ensuring that the system fits in the electronic cabinet. Its satisfaction of customer desires is very narrow compared to minimizing complexity. These rankings give us an idea of how general or specific each how is when meeting the requirements of the design.
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Elaborate the requirement list (Possible reference to HOQ). The following is the requirements list for this project. It has been constructed based on the problem statement that was provided. The demands and wishes were based on deliverables that were expected from this project versus what was only a suggestion. Requirements List for a Water Cooling System for an Electronic Cabinet
ME 6101A
Issued on: 10/26/06 Page: 1/1
Problem Statement: The project that has been posed for validation is to design a water-cooling system for an electronic cabinet.
Changes
D/W
D D D D D D D D
D D W W W W W W W D W D W W
Requirements Geometry Cabinet Dimensions in meters: 0.61(width)*1.02(depth)*2(height) Server center dimensions in meters: 0.51(width)*0.71(depth)*0.333(height) Server dimensions in meters: 0.051*0.71*0.333 Chip dimensions in cm: 3*3*0.2 Energy Chip heat flux: 100 watt/cm2 Minimum available chilled water temperature: 5°C Maximum available chilled water temperature: 25°C Maximum chip temperature: 85°C Kinematics Maximum available chilled water flow rate: 180LPM(0.003m3/s) General Design for manufacturability Minimum cost Modularity Mass customization Robustness Design for future in 2020 Environmentally friendly design Self-sustainable Has to be completed by the beginning of December, 2006 Recyclable materials Safety Simplicity Maintenance
Responsibility Design Team Members
Hayer, Baker, Nema, Olson 25
Group Feedback Since we formed the requirements list as a group, we did not need to provide individual input on the list after the planning phase was finished. After finalizing the requirements list, however, we consulted Emad Samadiani, one of our project sponsors, to obtain feedback on our progress. After he provided comments and approved of our work, we continued to the conceptual phase. Revise Plan of Action After the planning phase we realized that the end-of-semester presentation would be a week earlier than expected, so we shifted our tasks on the Gantt chart to account for the shorter amount of time we had to complete the project. The Gantt chart suggested that the requirements list be completed by the third week of October. However, we were behind schedule a week, so we had to revise our Gantt chart to contain more conceptual design tasks in a shorter amount of time. Revise Allocation of Tasks In the planning phase, we decided that every group member would have basically the same responsibility of researching current designs of water cooling systems for an electronic cabinet. We knew though, that the conceptual design phase would make use of our specific skills, so we allocated the task of computer modeling to Lucy and mostly Harjot and Gaurav would do the calculations. All other activities in the conceptual design phase would be done as a group. Since Jeff was only auditing the class, we merely expected him to help us form concepts during our brainstorming sessions.
Hayer, Baker, Nema, Olson 26
5.2 Conceptual Design Identify essential problems .
In the clarification of the task, we created a house of quality to relate the customer wants to the engineering how’s. Unfortunately that did not tell us how important the requirements relative to one another. In the clarification of task step, we explained that there would be a prioritization matrix to find these rankings. The diagram above determines the weights of the requirements. The order of importance goes from 1 for the demands to low numbers for important wishes to 7 for the least important desire of the customer. The tree on the left branches the requirements from overall areas that need to be satisfied to specific demands and wishes. The matrix on the right shows the relative importance of one requirement to another. For example, 0.5 : 0.5 means that two requirements are equally important, whereas 0.8 : 0.2 means that the first requirement is much more important than the second one. Each row is summed in a “total” column. This total is divided by the sum of the values in the “total” column (in this case, 230.6). This is the weight of each requirement. The weight is multiplied by 100 to get a percent importance. The ranking in the rightmost column is assigning a 1 to the highest percent importance, then a 2 to the next highest percent importance, and so on. The advantage of this chart is that it combines a tree diagram and a matrix diagram into one diagram.
Hayer, Baker, Nema, Olson 27
Establish function structure.
Figure 5.2: Function Structure The figure above displays the overall function of the system we needed to design. We split this task into four main tasks. These functions were divided into subtasks until they could not be divided any further. We omitted the flow arrows for energy, materials, and signals because it would cause congestion in the figure and we thought it would be clear that the functions related to control would have signal flows in and out and that supplying water would have material flows in and out. The transfer heat box would have energy flows in and out of it. The arrows would be drawn from left to right because we drew the functions sequentially. By establishing a function structure, we were more able to see the possible modularity of the system before coming up with concepts.
Hayer, Baker, Nema, Olson 28
Search for working principles and working structures (Possible use of ideation tools).
To search for working principles and working structures, we used Lucy’s modified classification scheme to list and combine concepts. It can be seen that with the number of ideas we had for each function, there were 144,698,400 combinations. We decided that since the interrelationships of the components are not strong, many combinations could be left out of our list. For example, combinations that were almost the same except for having different valves did not need to be considered as two separate combinations. As a result, we made another table of the functions that made the most variation in the overall concept. This table can be found in the next section.
Hayer, Baker, Nema, Olson 29
Combine and firm up into concept variants (Classification Scheme/Advanced Decision Matrix).
The two functions that resulted in large variations in the overall concept were the method for transferring heat from the chips to the water and the mode of heat transfer. We created 7 combinations from the 4 methods and 2 modes of heat transfer. These combinations are listed in the lower half of the above table, along with their acronyms. Single-phase heat transfer refers to the working fluid being only in one phase. For our case, this is water in liquid form. Two-phase heat transfer, on the other hand, is when the working fluid is in two phases: liquid, and gas. The heat transfer in two phase is much higher than that in single phase because of the higher heat transfer coefficient, but it is difficult to achieve two phase heat transfer in the current application because the water temperature must stay below 85°C. The only way to attain the gaseous phase at this temperature would be to reduce the working pressure of the system. This would require additional components. A thin plate consists of a plate with serpentine tubing laid on the top. Water passes through the tubing, keeping the plate cold and maximizing the transfer of heat from the chip to the plate.
Hayer, Baker, Nema, Olson 30
Figure 5.3: Thin Plate Concept The microchannel concept is a plate with grooves milled into the top surface. Water passes through these grooves to keep the plate cool. This idea is called a microchannel device because the channels are incredibly small.
Figure 5.4: Microchannel Concept A water block is a plate with a few large channels passing through it. Water passes through the channels and the heat from the chips is transfer to the plate by conduction.
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Figure 5.5: Water Block Concept Direct contact is the immersion of the chip in water. The chip is encased to prevent water from touching it.
Water
Chip Figure 5.6: Direct Cooling Concept
Hayer, Baker, Nema, Olson 32
Evaluate against technical, economical, environmental/green engineering and ethical criteria (Use of Preliminary Selection DSP and Selection DSP). Preliminary Selection The following figures show Preliminary Selection DSP for three different datums. After each figure with calculations, another figure with the reasoning behind the values is shown. This method allows the designer the ability to compare concepts against a datum based on a design criterion. The downside to this method is that although it may tell you that ‘A’ is preferred to ‘B’, it does not tell you by how much. Also, the datum must be changed and the process must be repeated to ensure relevant results. For this case, we had 7 total concepts, so it was fitting that we redo the calculations at least three times. Datum: WBSP
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Datum: TPSP
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Datum: DC
Hayer, Baker, Nema, Olson 37
Hayer, Baker, Nema, Olson 38
Prelim inary Concept Selection 4.5
4
3.5
3
Dat um: WBSP
2.5
Dat um: TPSP 2
Dat um: DC
1.5
1
0.5
0
WBSP
WBTP
MCSP
MCTP
DC
TPSP
TPTP
Concept Variants
Figure 5.7: Results from Preliminary Selection The top three choices from the Preliminary Selection DSP were analyzed further in the following section. The figure above shows that for all three datums, water block single phase (WBSP), microchannel single phase (MCSP), and thin plate single phase (TPSP), were the three best choices. This was fitting considering that to achieve two-phase, as discussed earlier, requires a large amount of additional effort. We understand that the results from this method are not anchored in mathematics, so if the three concepts were not capable of achieving the required heat transfer, than two-phase would have to be reconsidered.
Hayer, Baker, Nema, Olson 39
Selection Selection is one of the most important aspects of design. It is defined as “the process of making a choice between a number of possibilities taking into account a number of measures of merit or attributes.” But more often we must consider the compromise decision, or “the process of determining the ‘right’ value or combination of design variables, such that the system is feasible with respect to constraints and system performance is maximized.” The following calculations were performed using engineering software called EES. The detailed program can be found in the appendix. The inputs for the program are the required heat transfer rate and the dimensional constraints. Using forced convection heat transfer correlations, the program outputted the pressure head and flow rate of the water required to achieve this heat flux.
Dittus Boelter correlations were used for the water block and the thin plate [27]. The correlations for the single phase heat transfer and the pressure drop inside microchannels was taken from reference 28. During the calculations for the thin plate concept, we realized that the effective area of heat transfer was very small. In fact, ideally there is only a line contact with the tube and the plate. For our calculations, we have taken the area of contact as 10% of the total area of the tube. This explains the extremely high value for the pressure drop and the flow rate for this concept.
Line Contact
Figure 5.8: Line Contact between Tube and Plate The attributes used for the comparison were both quantitative and qualitative. A ratio scale was used for the quantitative characteristics and an interval scale was used for the qualitative. Based on the relative importance of each attribute, determined from the prioritization matrix, a normalized score was assigned. To ensure that the results were consistent, we considered the sensitivity of the results by tweaking the normalized score for each attribute by adding and subtracting 5%.
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Rank and normalized score for design criteria are presented in the following table, with normalized scores for sensitivity analysis: Attributes
Relative Rank
Normalized Score
Normalized Score + 5%
Normalized Score - 5%
Heat Transfer Rate
1
0.171
0.179
0.162
Pressure Drop (Pump Head)
2
0.146
0.153
0.139
Size
3
0.122
0.128
0.116
Water Flow Rate
2
0.146
0.153
0.139
Number of Components
4
0.098
0.102
0.093
Amount of Material
4
0.098
0.102
0.093
Cost
5
0.073
0.077
0.069
Simplicity/Manufacturability
6
0.049
0.051
0.046
Mass Customization/Modularity
7
0.024
0.026
0.023
Maintenance/Operation
7
0.024
0.026
0.023
Maintenance/ Operation
Mass Customizatio n/ Modularity
Simplicity/ Manufacturab ility
Cost
Amount of Material
Number of Components
Water Flow Rate
Size
Pressure Drop (Pump Head)
Heat Transfer Rate
Results from the performed analysis are provided in the following table, detailed program for the technical criteria can be seen in the appendix:
900
3x3x1= 9
700
3
27
0.2
0.2
0.2
0.2
WBSP
100
1
3x3x1= 9
1.5
3
43
0.2
0.7
0.2
0.7
8
3
21.3
1
1
0
1
MCSP
100
85
3x3x.3= 2.7
Range
>100
0-100
0-30
0-180
Type
R
R
R
R
R
R
I
I
I
I
Preference
H
L
L
L
L
L
L
L
H
L
Units
W/cm^2
M
cm^3
L/min
None
grams
None
None
None
None
Mass Customizatio n/ Modularity
100
Simplicity/ Manufacturab ility
TPSP
0-200
Maintenance/ Operation
1
0
0.7
0
1
0.86
0.8
0.8
0.2
0.8
WBSP
1
0.99
0.7
0.99
1
0.78
0.8
0.3
0.2
0.3
MCSP
1
0.15
0.91
0.95
1
0.89
0
0
0
0
Cost
Size
Amount of Material
Number of Components
TPSP
Pressure Drop (Pump Head)
Water Flow Rate
Heat Transfer Rate
Normalized scores for the results provided in the next table:
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An explanation for the qualitative criteria: Cost
Simplicity/ Manufacturability
Mass Customization/ Modularity
Maintenance/ Operation
0
There are no costs associated with this concept
Does not require any fabrication.
No parts are interchangable.
Requires no user input.
0.2
Cost for this concept is very low with respect to other components in the cabinet (average price for the chips).
Some parts can be If any parts fail, they can Requires very little customized for better heat be changed without fabrication using simple transfer rate, but nothing much added effort from manufacturing techniques. else can be changed. an unskilled person.
0.5
Costs are not unreasonable for this concept as compared to other components in the cabinet.
Requires some fabrication, Parts can be changed for Parts can be maintained but processes are not heat transfer and different and adjusted by an atypical. size chips. engineer.
0.7
This concept requires a lot of expense, almost as much as other the components in the cabinet.
1
Fabricated parts use expensive manufacturing processes.
All parts must be Costs for this concept fabricated using outweigh the cost for the complicated manufacturing components in the cabinet. processes.
Parts can be changed to adjust for different flow rates, pressure, size of chips, and heat transfer rates.
Parts that fail can be maintained by a skilled professional.
All parts are interchangable.
Parts cannot be maintained, must be replaced.
Merit function showing the rank for each concept from different normalized values:
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Figure 5.9: Results from the Selection Process From this analysis, we found that the water block single phase is the most preferable choice of the three concepts. If the space constraints were stricter for the design, then the microchannel concept would be more desirable. Group Feedback To conclude the conceptual design phase, the group double-checked the calculations to confirm their correctness and that the final concept chosen was appropriate. Revise Plan of Action We did not need to revise the plan of action at this point because the group was not straying from the schedule of the Gantt chart from the end of the planning phase. Revise Allocation of Tasks In the conceptual phase we performed calculations and created computer models of different concepts. In the embodiment phase, we needed to form preliminary layouts and select the best layout for our design. In addition, we knew that we were going to draft a computer model of the entire cabinet with our components in place. We continued to target individual skills by asking Lucy to create the computer model, but since forming a layout did not require specific skills, the group worked on this task as a whole.
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5.3 Embodiment Design
Preliminary form design, material selection and calculation. (Possible use of simulation and computational modeling tools, e.g., FEA)
Figure 5.10: Detailed program code from EES for the Water Block Concept
Figure 5.11: Results from using EES on the Water Block
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Chips with Water blocks
Figure 5.12: Preliminary Layout of the Water Cooling System The figure above shows the preliminary layout of the cooling system. The components used are: chiller, pump, valve, flow control system, and water blocks. • Chiller: The purpose of the chiller is to cool the water to the desired temperature, in this case, 10°C. We did not concentrate on the design of the chiller because it was not within the scope of this project. • Pump: The pump is used to maintain the appropriate water flow rate in the system. • Valve: A manual valve was placed after the pump to regulate the flow rate in case of emergency. For example, this valve would be used if the flow control system fails or there is a leak in the system. • Flow Control System: This system is used to adjust the water flow rate when there are slight variations in pump output. It also has temperature and flow sensors built in so that when the temperature of the water shoots up too high or the water flow rate is too small, the electronic components are shut down. • Water Blocks: The water blocks are used to transfer the heat from the chips to the water. The material of the water block was chosen as copper because of its excellent thermal conductivity and low cost.
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Draft Computer Model for Final Concept
Figure 5.13: Water Block as it Connects to the Chip
Figure 5.14: Connection between Water Blocks
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Select best preliminary layouts. Based on possible solutions for this application, some concepts were overlooked from the classification scheme to come up with the following table of possible options for each component.
Pump From the options that we listed for the pump, we chose the centrifugal pump. The gravity-pumping scheme was not suitable because we needed a pressure head, which was not possible to achieve by this scheme. The reciprocating pump causes much vibration that was not desired. For this flow rate the rotary vane and diaphragm pump were not suitable.
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Flow regulating valve For the flow-regulating valve that is required after the pump, we needed a manual valve. The needle valve was the cheapest and reliable enough to serve this purpose. Control system For the temperature sensor in the control system we chose a thermocouple because it was the cheapest temperature sensor among the ones that are capable of outputting an electrical signal (control system need electrical inputs from sensors). We did not need the high sensitivity of an RTD, IR thermometer, or laser. As for the mercury thermometer, it was out of the question because it cannot provide an output in terms of electrical signals. For the selection of the flow rate sensor, we used a similar approach as the temperature sensor. The options like pitot tube, venturi meter, orifice meter and rotameter were not able to produce the output in terms of electrical signals. The coreolis mass flow meter, ultrasonic flow meters were too costly to implement. For the flow-regulating valve of the control system, we need a valve that was suitable for an automatic control system. The only valve that we found that was cheap enough to serve this purpose was a solenoid valve. The needle and manual valves cannot be automated and the control valve option was too costly.
Refine and improve layouts. (Possible use of simulation and computational modeling tools) With the limited time, we could not further refine the layout using detailed computer simulations and modeling. But, the calculations that were performed satisfy the basic requirements. Evaluate against technical, economical, safety, environmental/green engineering, and manufacturing aspects. The technical criterion was satisfied because this design meets the requirements for heat transfer and the flow rate. Apart from this, the design was compact enough to fit the special constraints. When designing this concept and selecting parts for this concept, economical factors were considered. Although the final product may seem too expensive, with mass production many costs can be reduced. The safety of the final product was a primary concern. A control system has been incorporated to ensure the safety of the electronics by making certain that the water flow rate or the temperature does not vary from the nominal level. Also, a manual valve has been incorporated for the rare instance of a ruptured pipe. For environmental concerns, we took care to follow the guidelines for green engineering as established in the checklist below. This concept does
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not use any type of refrigerant and material usage has been minimized. Also, when choosing different parts for the layout, recyclability of the materials and the energy consumption was considered, but was not the number one criteria in the selection of parts as explained earlier. To design for manufacturability in this project was simple considering most parts were off the shelf. The only part that may be of concern is the water block. We decided the most appropriate manufacturing process for the water blocks would be the casting process since products are readily mass produced, at a reasonable cost. The water blocks would have to be cast in two pieces and then joined together, which is not the best for manufacturing. But, since the water block is a simple shape, the appropriate tolerances can be achieved for alignment. Plus, with this shape, undercuts are not an issue.
The following table shows the guiding principles in green engineering [4]: Engineer processes and products holistically, use systems analysis, and integrate environmental impact assessment tools. Conserve and improve natural ecosystems while protecting human health and well-being. Use life-cycle thinking in all engineering activities. Ensure that all material and energy inputs and outputs are as inherently safe and benign as possible. Minimize depletion of natural resources. Strive to prevent waste. Develop and apply engineering solutions while being cognizant of local geography, aspirations, and cultures. Create engineering solutions beyond current or dominant technologies; improve, innovate, and invent (technologies) to achieve sustainability. Actively engage communities and stakeholders in the development of engineering solutions. Eliminate weak spots At first, we decided on metal tubing for the pipeline, but we realized that it was not very flexible, making it difficult to make around sharp bends. Also, if metal piping was chosen, the possibility for condensation was very high at this low water temperature, making it a concern in the electronic cabinet. So, to eliminate this weak point, we changed all the tubing to Teflon. Although this added some additional costs, it was well worth it considering the added safety. Check for errors, disturbing influences and minimize cost. To ensure that we did not make a severe error in the calculations, we discussed the results with a 3rd year PhD student conducting research in the thermal sciences. With his consent, we felt our results were legitimate. We realized that there are some disturbing factors for this design. The temperature of the room (ambient air) has some contribution Hayer, Baker, Nema, Olson 49
to the working fluid temperature, but we found that the heat transfer from the air is negligible as compared with the high heat flux from our system, so it was disregarded. To minimize cost, we noticed that the needle valve that was chosen was extremely expensive as compared with other components in the system. Since it is a manual valve, this did not seem suitable. Therefore, we continued shopping for a cheaper valve, and found one that was less than half the price as our original. Prepare the preliminary parts list and production and assembly documents.
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Group Feedback At this point, we realized some sacrifices have to be made for time constraints. We could not refine the layout any further using computer modeling or simulations, but it was agreed upon that with the requirements met for heat transfer and flow rate it would not be unsatisfactory. Revise Plan of Action No revisions were made to the plan of action. Revise Allocation of Tasks The detail design phase would most appropriately be done as a group, so we did not make any changes. 5.4 Detail Design Elaborate detail drawing and parts list. The following table is the bill of material for this project:
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Complete production, assembly, transport and operating instructions.
Figure 5.15: Final Layout
Figure 5.16: Final Layout Zoomed In on Water Blocks
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Figure 5.17: Final Layout of Water Blocks Check all documents. The documents were checked to verify all aspects of the report fully address the topics covered by Dr. Mistree’s Note Sheet for the Project. Also, the report was checked to ensure that it flowed, and that the organization made sense. Group Feedback The group agreed that the work done was more than acceptable and the primary focus should be shifted to preparing the end-of-semester presentation.
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6.0 Evaluation of the Method 6.1 Critical Evaluation of Augmented Method To evaluate the method, the questions pertaining to the project must now be addressed. Based on the answers, we can evaluate whether the process is viable using the validation square for the two quadrants being analyzed. However, only two quadrants of the validation square will be considered, so it will not be possible to validate the entire method. This aspect will be left to the answer to the question for the semester. The following table shows the question and the corresponding conclusion drawn from the project. Question to be Addressed Does the augmented method work?
Validation We were able to reach a final design systematically and efficiently. The structure of the method was consistent and there were no jumps between steps. The added tools were effective for their intended purpose. How useful is the resulting design from this The resulting design from this method has method? been able to address most of the requirements of the customers. The requirements of heat flux, water flow rate, space constraints, material, energy, cost, and modularity were satisfied. Are there systematic steps that seem The results from the house of quality did unnecessary? not properly rank the requirements in order of importance. The combination scheme generated unnecessary combinations, so we had to add a step for analyzing the interrelationships between components to create very different concepts. Where should design for manufacturing be Design for manufacturing should occur as placed in the method? early as in the requirements list, selecting concepts and all the way through the detail design phase. Does the systematic method hinder or We found that the systematic method support creativity? supports creativity. By establishing the function structure it became easy to come up with lots of ideas for the working principles and concept variants. Should any more steps or tools be added? The version of P&B method verified in this project was developed while the midterm. After that more augmentations were
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Should any steps or tools be moved?
Is the method adaptable for the world of 2020?
Does the method support a distributed design environment and a global marketplace?
suggested in the class. The tools like concurrent engineering, interoperability, compromise DSP, strategic design has to be added in the method. Also, group feedback, revision of plan of action, and the revision of the allocation of tasks after the definite layout is unnecessary considering it is still in the embodiment phase. These steps have been considered after the embodiment phase is complete. Initially, Draft Computer Model was placed in the conceptual phase before we evaluate the concepts. But, we realized that creating a detailed computer model for each concept was not an appropriate use of time. Also, without hard data, dimensions are not available. Therefore, it was moved to the embodiment phase after all the calculations have been performed to establish the correct dimensions. The world of 2020 was used when defining the augmented requirements list for the method to ensure the design process was adaptable for the future. By considering all the drivers for the world of 2020, we came up with the requirements list; we could see what steps needed to be added to the process. Specifically, steps that were incorporated for mass customization, environmental and ethical issues, teamwork, using computer models and simulations, manufacturing, and workplace efficiency address the world of 2020 in the project and these factors can mostly be seen being implemented in the selection part of the conceptual phase. Many steps were added for a global marketplace, but were disregarded from the project tasks for the verification as described in the midterm report. But, we did consider a distributed design environment. To make certain the method was adaptable to distributed design, we tested it by having each member work individually using an online chat room. We found that the method was still
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Is the process conducive to collaborative efforts?
Do the augmentations sufficiently address environmental and ethical issues?
Are reiterations of steps easily executed in the process?
productive, but individual responsibilities had to be clearly defined, as described in Design Team Structure. The method was found to support teamwork. By implementing the team contract we were able to define the mode of conduct and responsibility of members. The group feedback scheme after each phase helped us to ensure that the we were on right track and to revise the plan of action as necessary (for example the project deadline was shifted from 12th December to 7th December accordingly we revised our plan of action after planning and clarifying the task) The augmentations like considering environment as a selection criterion while choosing the concept variant and various other decision making steps has enabled us to reduce the material and energy consumption of the final design. We could not check for the ethical issues because in this project we did not face any serious ethical dilemma. We never reiterated any phase of the method in this particular project hence the answer to this question could not be answered.
The empirical structural validity is justified considering that the example problem that was chosen can address the important questions about the method. The project tasks correspond with the questions to be addressed quite well (refer to Relation of Questions to be Addressed to Project Tasks) except for one exception. From this project, we could not verify if the process can adapt for a global marketplace because we did not include that aspect in the project tasks. Although there have been numerous additions for design for a global marketplace, we did not have the time to confirm that the augmentations would work. As for the empirical performance validity, the project has surely justified our claims based on the answers to the questions from above. Although some changes should be made, the overall effectiveness of the design methodology has certainly been established.
Strengths of the Project
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One strength of this project is that it fulfills most of the customer requirements. The heat flux other technical specifications have been met, while other demands for the special constraints, cost, environmental aspects, and manufacturability have been taken into account. Another strength is that the design is modular so if it was required, any component can be replaced while the rest can remain unchanged. For example, if the requirements are for a larger heat flux, a larger pump can replace the existing pump. Finally, this project allowed us to analyze many of our systematic design steps, including augmentations.
Limitations of the Project One of the main limitations to this project is that we did not have a chance to further refine the layouts using computer simulations in the embodiment phase. Also, we did not get to explore the use of different materials. Although copper is considered the norm for thermal applications similar to this, it is always a good idea to check all the options. Finally, we did not do the detailed design of the flow control system. Although components were chosen for the flow control system, we did not write the programming code for the microcontroller. Future Work As pointed out in the limitations of the project advanced simulations of the heat exchanger and the other components can be performed to get a more optimized design. A prototype of the proposed design can be made to check its real time performance. We could not consider any market analysis to formulate the product proposal. A market and customer analysis should be done and the global marketplace should be considered. The design should also consider the robustness of the system. We could not check extensively the capabilities of the method to suit a distributed design environment. To verify this a team situated at geographically diverse places may have been considered. For example a team of distance learning students situated at different places would help verifying this aspect of the method.
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6.2 Value/Lessons Learned Progress towards Team A0 goal Learn how to implement and evaluate the design method. Most of the steps of augmented P&B method have been implemented in this project. The proposed tools like team contract, time management tools, House of Quality, PDSP and DSP, classification scheme, computer simulations and group feedback has been used extensively to come up with the design solution. A series of questions have been posed and answered by the project to verify and evaluate the proposed design method. Therefore a significant amount of progress has been mad toward this learning goal through the project. Learn how to work effectively and efficiently. We learned how to plan and schedule our work by the use of time management tools. The team contract helped us to define the mode of operation and responsibility of each member of the team. Through the use of Need-Strength-Matrix we learned how to identify our skill set and use towards achieving our objective effectively. The group feedback scheme helped to track the progress of the project and revise the plan of action as necessary. In sum, through this project we learned to work effectively and efficiently in a team. Learn how to communicate professionally. Through organizing and presenting out work via the consultant and contractor’s reports we learned how to write professional reports. By presenting our ideas in mid-term and end of semester presentations we learned how to communicate and impress our clients. Learn how to evaluate our own work. By exploring the relationship between the Q4S and the project through validation square we learned how to formulate the strategy to evaluate our proposed P&B method. By posing a series of questions and answering them we learned how to criticize and evaluate our own work. Through the discussion of future scope of the project we learned how to keep building on our work. In sum, the team has learned a lot and made a significant progress towards achieving the learning objectives through the project.
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References: 1. Pahl, G. and Wolfgang Beitz. Engineering Design: A Systematic Approach, Second Edition (2005). Springer-Verlag London Limited 1996. Great Britain. 2. National Science Foundation. Green Engineering: Defining Principles Conference (2003). http://www.innovations-report.com/reports/reports.php (accessed: 9/20/2006). 3. Crowder, R. A Future Vision for the Engineering Design Environment: A Future Sociotechnical Scenario (2003). http://eprints.ecs.soton.ac.uk/8188/01/1517ICED03FP.pdf (accessed: 9/20/2006) 4. National Academy of Engineering. The Engineer of 2020: Vision of Engineering in the New Century (2004) THE NATIONAL ACADEMIES PRESS. Washington, DC. 5. Spiegelman, Helen. "Beyond Recycling: the Future of Waste." Enough! Spring 2003. 6. Perry, Marc J., and Paul J. Mackun. Population Change and Distribution 1990 to 2000. United States Census Bureau. 2001. 7. http://newsfromrussia.com/science/2004/04/09/53323.html 8. http://auto.howstuffworks.com/hydrogen-economy.htm 9. http://news.bbc.co.uk/1/hi/sci/tech/1727312.stm 10. http://science.howstuffworks.com/solar-cell.htm 11. http://news.bbc.co.uk/2/hi/health/4396387.stm 12. http://www.vnunet.com/computing/features/2072409/paperless-paradise-edgescloser 13. http://computer.howstuffworks.com/quantum-computer.htm 14. http://armageddononline.tripod.com/icecaps.htm 15. http://science.howstuffworks.com/question473.htm 16. http://www.ontheissues.org/askme/ice_caps.htm 17. http://www.nrdc.org/globalWarming/qthinice.asp
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18. http://www.commondreams.org/headlines06/0811-06.htm 19. http://www.worldwideschool.org/library/books/hst/northamerican/WorldwideEffe ctsofNuclearWar-SomePerspectives/chap1.html 20. http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6357743 21. http://www.uow.edu.au/arts/sts/bmartin/pubs/82cab/index.html 22. Raghu, A. Designing the Answer to the Q4S (Fall 2001). Georgia Institute of Technology. 23. Malone, T & Murray, P. Assignment 6 Midterm. (Fall 2003). Georgia Institute of Technology. 24. "Sustainability." Wikipedia. . 25. Dang, Bing. "Liquid Cooling with Microfluidic Channels Helps Computer Processors Beat the Heat." Physorg.Com June-July 2005. 19 Nov. 2006. 26. http://www.motivation-tools.com/workplace/ 27. Incropera & DeWitt. “ Fundamentals of Heat and Mass Transfer,” 6th Edition. University of Connecticut, USA [2005]. 28. Peng & Peterson. “Convective Heat Transfer and Flow Friction for Water Flow in Microchannel Structures,” International Journal of Heat and Mass Transfer, Vol. 39, No. 12, PP. 2599-2608, [1996]
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Appendix EES program for the water block: {heat exchanger design} {flow is divided into m paths with n chips in each path} m=6 n=60/m A_chip=9[cm^2] Q_water_overall=0.0004[m^3/s] Q_water_path=Q_water_overall/m q_chip=100[w/cm^2] T_chip=85[C] T_property=15 [C] Q_water_path*Rho_l*Cp_l*delta_T=0.9 {T_mean_water=10[C]} Rho_l=density(water,T=T_property,X=0) mu_l=viscosity(water,T=T_property,X=0) Cp_l=SpecHeat(Water,T=T_property,X=0) K_l=conductivity(Water,T=T_property,X=0) Re_Dh=Rho_l*V_avg*D_hyd/mu_l Pr=Prandtl(Water,T=T_property,X=0) {water block design} D_hyd=0.004[m] thickness=0.002[m] {A_waterblock_contact=} q_chip_overall=A_chip*q_chip {q_effective=q_chip_overall/A_waterblock_contact} h*D_hyd/K_l=0.023*Re_Dh^0.8*Pr^0.4 h*A_heat_transfer*(T_mean_surface-T_mean_water)=q_chip_overall {heat conduction in the block} K_copper=400[w/m.k] K_copper*(T_chip-T_mean_surface)/thickness=q_chip*100^2 Length_tubing=A_heat_transfer/(4*D_hyd) Length_tubing=0.12 {Pressure drop} V_avg=Q_water_path/D_hyd^2 delta_P=f*Rho_l*V_avg^2*(Length_tubing/D_hyd)/2 f=(0.79*ln(Re_Dh)-1.64)^(-2)
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EES program for the thin plate: {heat exchanger design} {flow is divided into m paths with n chips in each path} m=6 n=60/m A_chip=9[cm^2] {Q_water_overall=0.003[m^3/s]} Q_water_path=Q_water_overall/m q_chip=100[w/cm^2] T_chip=85[C] T_property=15 [C] T_mean_water=10[C] Rho_l=density(water,T=T_property,X=0) mu_l=viscosity(water,T=T_property,X=0) Cp_l=SpecHeat(Water,T=T_property,X=0) K_l=conductivity(Water,T=T_property,X=0) Re_Dh=Rho_l*V_avg*D_hyd/mu_l Pr=Prandtl(Water,T=T_property,X=0) {water block design} D_hyd=0.004[m] thickness=0.002[m] {A_waterblock_contact=} q_chip_overall=A_chip*q_chip {q_effective=q_chip_overall/A_waterblock_contact} h*D_hyd/K_l=0.023*Re_Dh^0.8*Pr^0.4 h*A_heat_transfer*(T_mean_surface-T_mean_water)=q_chip_overall {heat conduction in the block} K_copper=400[w/m.k] K_copper*(T_chip-T_mean_surface)/thickness=q_chip*100^2 Length_tubing=A_heat_transfer/(0.1*D_hyd) Length_tubing=0.12 {Pressure drop} V_avg=Q_water_path/D_hyd^2 delta_P=f*Rho_l*V_avg^2*(Length_tubing/D_hyd)/2 f=(0.79*ln(Re_Dh)-1.64)^(-2)
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EES program for the microchannel: {heat exchanger design} {flow is divided into m paths with n chips in each path} m=6 n=60/m A_chip=9[cm^2] {Q_water_overall=0.0005[m^3/s]} Q_water_path=Q_water_overall/m q_chip=100[w/cm^2] T_chip=85[C] T_property=15 [C] T_mean_water=5[C] Rho_l=density(water,T=T_property,X=0) mu_l=viscosity(water,T=T_property,X=0) Cp_l=SpecHeat(Water,T=T_property,X=0) K_l=conductivity(Water,T=T_property,X=0) Re_Dh=Rho_l*V_avg*D_hyd/mu_l Pr=Prandtl(Water,T=T_property,X=0) {microchannel design} D_hyd=0.0006[m] Wc=0.002[m] H=0.0006[m] W=0.0006[m] Z=min(H,W)/max(H,W) thickness=0.002[m] q_chip_overall=A_chip*q_chip {q_effective=q_chip_overall/A_waterblock_contact} h_heat*D_hyd/K_l=0.072*Re_Dh^0.8*Pr^(1/3)*(D_hyd/Wc)^1.15*(1-2.421*(Z-0.5)^2) h_heat*A_heat_transfer*(T_mean_surface-T_mean_water)=q_chip_overall {heat conduction in the block} K_copper=400[w/m.k] K_copper*(T_chip-T_mean_surface)/thickness=q_chip*100^2 Length_tubing=A_heat_transfer/(4*D_hyd) Length_tubing=0.30 {Pressure drop} V_avg=Q_water_path/D_hyd^2 C_f_t=38600*2 {delta_P=2500000} delta_P=f*Rho_l*V_avg^2*(Length_tubing/D_hyd)/2 f=C_f_t/Re_Dh^1.72
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