US Energy Consumption and Efficiency: Understanding Energy Sources, Uses, and Losses - Pro, Study notes of Mechanical Engineering

Download US Energy Consumption and Efficiency: Understanding Energy Sources, Uses, and Losses - Pro and more Study notes Mechanical Engineering in PDF only on Docsity! MEEN 315, SECTION 503 PRINCIPLES OF THERMODYNAMICS Fall 2013 Homework #1 DUE September 3, 2013 1. Purchase and register your i>clicker remote (or subscribe to and register with i>Clicker GO). The i>clicker remote is available from the MSC Bookstore or via online purchase. You can purchase either the i>clicker or the i>clicker2 (you may want to see if other courses require one or the other, and get the same one). You may use your smart device instead of buying a remote; this requires a subscription to i>clicker GO. Regardless of your choice of device (remote vs. i>clicker GO subscription), you must register it before the start of class on Tuesday, September 3. To register, go to this website: http://www.iclicker.com/. Here is how you fill out the form: a) For the question, “Does your school use a Learning Management System (such as Blackboard, Moodle, etc.)?”, Answer NO. b) First name is self-explanatory. c) Last name is self-explanatory. d) Student ID is your UIN without any dashes. e) The remote ID is the 8 digit ID (composed of numbers and letters) on the back of your i>clicker remote (does not apply for i>clicker GO) f) The image code is self-explanatory. g) Be sure to click “register”. h) Print out your confirmation page and submit it as the “answer” to this problem. Please note: You will have a quiz in lecture on Tuesday, 9/3, which will require you to use i>clicker. Failure to participate in this quiz will cause you to lose points for this problem as well as for your participation assessment that lecture. Solution: Assessed via lecture quiz. 2. Learn about your syllabus! Review the syllabus that is posted on the e-learning website (i.e., syllabus. pdf on the main page). Be sure to pay attention to details such as the Grading, Participation, Homework, Project, Exams, Late Assignments, E-Learning, Prerequisites, the textbook, the peer evaluation, and the ABET Learning Outcomes. There will be a lecture participation assessment on Tuesday, September 3 asking you questions about your syllabus! Please note: If you fail to accomplish #1, you can submit your answers to #2 (quiz in lecture on Tuesday, September 3) on a piece of paper with your name and answers on it. Please note, this is the only exception that will be allowed for not having your i>Clicker registered and ready to go. Solution: Assessed via lecture quiz. 3. Replicate the diagram for a general thermodynamic control system. Write the general First and Second Law equations. Define the terms used on the diagram and in the equations. Solution: Next page. .. 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I,~++- ~ f)5~} ~"-~ of- ~'C~~: \F~ i= ~ J f ?,-:,. ./-.:ntLi J 1 F~~D ::2:~:¢~ F~t"", + t:f' F H~O t'Q.(..v,·A f 1- wyr- = rlf~O f"'i""':: I...f"",::::' 14_::r fs, 0.. {Co"'vtl>l~ FC.e.J..x. PfP; #r~ d = 3':L If +f./s :J (1'1. 7- ~) (0.10 (I;;;) 1- (~DO It..,)(3J.J1%-) 3.:1. I~ Ib.... -.ttILf _ .~.. -- F\.I;! 0 ~ 11.1- Uf ~ r-j4. v ;::Pit"0 F.. ,o ::; 'III . 1- lbJf- , tC Af' 0, ( H~ 1'1't.Nt ... PI-!:/Q =- J. "l, (" ill :: :2"8·6i.~~ f'>'l~ 5. Welcome to thermodynamics! As we discussed in lecture, thermodynamics is a broad subject that encompasses several important laws that, to this date, are shown to apply universally across our study of nature, from cosmological to sub-atomic scales. Fortunately for us, however, we will stay centered on its specific relevance to engineering; which means we will mostly stay centered on the effort to convert one form of energy into mechanical energy (i.e., work energy). We will discuss in lecture what “forms” of energy we have at our disposal, and what it means to convert one form of energy into “mechanical energy”. For now, though, I am interested in you getting a sense of the “big picture” of our (as in, the United States) sources of energy, how we use this energy, and how well we use this energy. This latter aspect – i.e., how well we use energy – is going to be a major theme this semester and can be reduced to the single word efficiency. More on this later. Please see on the next page what is called an energy flow graph. There are several important features to describe on this graph, which I will walk you through now. The first item to note is that energy “sources” are listed on the left hand side (e.g., nuclear energy, hydro energy, biomass energy, natural gas energy, coal energy, and petroleum energy). The second item to note is that there are different “sinks” that use or convert this energy; these are listed as the blocks in the middle of the graph (i.e., electric power sector, residential / commercial, industrial, nonfuel, and transportation). This second item would address how we use our energy. The third item to note is that each “sink” only uses a fraction of the source energy. Thus, the right hand side of the graph shows the amount of source energy that is put to use (i.e., “useful energy”) versus the amount of source energy that is lost (i.e., lost energy). This third item, of course, addresses how well we use energy. The fourth and final item to note is that all the numbers attached the various lines and boxes are the amount of energy for that particular item, in exajoules. As an example, in 2002 the United States (since this is the US Energy Flow Trend from 2002 – see the top of the graph) used 20.6 exajoules of energy in the form of natural gas. There are other details of the graph, such as how much of an energy source is imported or exported, which will not be the focus of this assignment (except it will help you answer question g). For your assignment, please answer the following questions. Enjoy! a) What is an exajoule? Is it a metric or English unit? b) In 2002, the United States used approximately 103 exajoules. What is the equivalent of this in BTU (British Thermal Unit)? c) Of the various sources of energy listed on the left hand side, which are considered “fossil fuels”, in the conventional sense? What percentage of the US’s energy sources in 2002 do fossil fuels comprise? d) Which energy sink (i.e., electric power, residential / commercial, industrial, non fuel, and transportation) uses the most energy, as a percentage of total US energy source? e) Natural gas is used, and in how much quantities, by which energy sinks? f) The transportation sink uses, and in how much quantities, which sources of energy? g) Should the summation of Lost Energy and Useful Energy add up to 103 exajoules? If you think it does, why doesn’t it? h) If efficiency is defined as useful work (or useful energy) divided by total energy used, what was the efficiency of the United States’ energy consumption in 2002? i) Describe as many possible reasons as you can for there to be “Lost Energy”. j) Suppose you have a 50 kg block of steel. If you have 103 exajoules at your disposal, how many times could you push this 50 kg block of steel around the earth at its equator? Assume the coefficient of friction is 2.710. Solution: Page following energy diagram. June 2004 Lawrence Livermore National Laboratory http://eed.llnl.gov/flow U.S. Energy Flow Trends – 2002 Net Primary Resource Consumption ~103 Exajoules Source: Production and end-use data from Energy Information Administration, Annual Energy Review 2002. *Net fossil-fuel electrical imports. **Biomass/other includes wood, waste, alcohol, geothermal, solar, and wind. 1.8 5.2 4.0 22.4 Lost energy 59.3 27.8 Electrical systemenergy losses 2.3 5.6 1.0 Net imports 3.8 Imports 6.0 2.7 0.9 Nuclear 8.6 Export 1.1 0.7 0.2 0.5 8.9 Hydro 2.7 Biomass/ other** 3.4 Electrical imports* 0.08 Bal. no. 0.3 Natural gas 20.6 Bal. no. 0.1 0.4 Coal 23.8 21.1 Nonfuel 6.3 Transpor- tation 27.9 Distributed electricity 12.5 Residential/ commercial 20.7 Industrial 20.1 Export 2.2 Bal. no. 0.9 3.6 0.02 0.1 16.1 Useful energy 37.1 15.5 5.54.22.4 27.0 U.S. petroleum and NGPL 15.7 Imports 25.6 8.7 8.2 Electric power sector 40.3 0.02 0.7 0.04