Project Renewable Insulation Example Teacher Notes

Transcription

1 Project Renewable Insulation Example Teacher Notes Sample Data and Teacher Notes This guide is designed to provide sample calculations, background, and tips for the teachers performing this project with the Vernier Stainless Steel Temperature Probes and LoggerPro Software. At the end of this guide is a copy of the project complete with sample data. Having the LoggerPro software installed on a number of computers will allow students to take their individual data files and complete a work of their choosing without tying up the log tag units. To set up LoggerPro to collect data, follow the steps below. POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 1

2 Set up the experiment length and the sampling rate. When you are ready to start collecting data, click Collect. POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 2

3 A typical screen from the LoggerPro software for the inside and outside temperature probes: Note that temperature automatically sets to C. If you need to change to a different unit, click on one of the Go!Link buttons, then click on the desired unit. Also note that the temperature probes do not need to be calibrated, so do not choose that option. POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 3

4 Data can be represented in the graph in various ways. Click on the axis labels and select the variable that you would like to have on each axis. A summary of the data can be obtained by following the steps below. It includes for each temperature probe selected max, min, time, and other info. Please note that the temperature occasionally dips, so the minimum recorded value may not be a value that you want to use. POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 4

5 Individual data points can be obtained by clicking the Examine icon at the top of the LoggerPro window. This is shown below. As the cursor is moved horizontally across the graph, the data points for each temperature probe are shown in the Examine box. POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 5

6 Amount of heat lost through the (un-insulated) bottom is not significant in this experiment (if a student should ask about it). We are ignoring the heat absorbed and released by the box and the insulating materials themselves. C p: air=1000, Styrofoam=1300, and acrylic=1470 J/kg C, which means that the air will experience a greater temperature change for the same amount of energy transfer. Air is also a better conductor of heat than Styrofoam or acrylic. We cannot measure R values with the heat box. The industry identifies R values by measuring heat flux (heat flow per unit area). Insulating material to be tested is placed between two metal plates held at different constant temperatures. The amount of energy flowing through the material or the amount of energy required to keep the plates at their constant temperature difference provides the data to determine R values. We are not at a steady state ΔT, so the P=Q/t=kAΔT/L equations do not apply. You also may want to calibrate your room and unit by running it with no insulation. This will allow the students to see the difference the insulation on the top can make. Here is sample data for a box as-is, 20 minutes on/off (same dimensions as indicated below). T-inside (start-max-final): 23.8, 54.8, 34.6 T-outside: 23.9, 49.9, 33.7 Q gained: J, Q lost: 94.51J, Q retained net: 50.53J ΔT (max) = = 4.9 C Below is the completed project, like an answer key, with sample data and calculations in red. POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 6

7 Project Renewable Insulation Introduction The largest amount of energy consumed within the average home is related to maintaining adequate climate control through heating and cooling systems. To conserve energy and decrease expenses associated with climate control, proper home insulation techniques are required. Insulation technologies relating to materials and application have advanced throughout the home building industry with time. The home building industry once relied on straw and newspaper for insulating material. The industry currently utilizes technology such as fiberglass and blown expandable foam. Insulation material advancement is driven by consumers demanding insulation material designed for high insulation value along with positive occupant health and environmental impact. Many homeowners today are designing new green homes. To meet the needs of green consumers, insulation manufacturers are developing insulating materials made from recycled products such as jeans, t-shirts, and other low volatile organic products that can be treated with boric acid. Manufacturers have found that many green materials have other benefits to the homeowner as well, such as cotton s ability to provide excellent soundproofing. Equipment Computer Heat box apparatus LoggerPro software 2 Stainless steel temperature probes Insulation materials Tape Standard and metric ruler Procedure Your team will design a renewable composite insulation material. Design Constraints: Composite insulation material must produce minimum heat loss, representing good insulating value. Composite insulation material must have overall uniform thickness less than or equal to one inch. Composite insulation material must have consistent internal composition. Individual insulation material(s) must be environmentally friendly. Individual insulation material(s) must be recyclable. POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 7

8 Individual insulation material(s) must be economical. Composite insulation material dimensions must not exceed the overall dimensions of heat box apparatus top. The change in temperature inside the box is directly related to the heat absorbed or released by the air in the box. Design Evaluation Data Collection: Pretest Data: Use a metric measurement device to calculate pretest data. The volume of air being heated is obtained by measuring the inside dimensions of the box. 1. Inner dimensions (m) l = w= h= Volume of air (m 3 ) (=l x w x h) V = Description of insulation material Towel, loosely folded to size of top of apparatus, 1in. thick, 8 layers Test Data: Plug two Stainless Steel Temperature Probes into two Go!Link connector. Plug the Go!Link into one of the computer s USB ports. Insert a temperature sensor with acquisition capabilities inside the acrylic top cover of the heat transfer apparatus. Place or attach your fabricated composite insulation material to the outside top surface of the heat transfer apparatus cover. Place a second temperature sensor with acquisition capabilities outside of the box to measure the ambient room temperature. Open the program LoggerPro on your computer by clicking Start, All Programs, Vernier Software, LoggerPro 3.8. Activate heat source and leave on for 20 minutes or until the inside temperature remains relatively constant. While the tester is heating up, Setup LoggerPro to take data for 20 minutes o Click Experiment, Data Collection. o Change the experiment length to 20 min and the sample rate to 4 samples per minute. o Click OK. Turn the heat source off and collect temperature data for 20 minutes. To do so, click on the green Collect Data icon at the top of the LoggerPro program. Once all of your data is collected, save the LoggerPro document. Remove temperature probes from the heat box. Return the temperature probes and the Go!Link connectors to your teacher. You may obtain the necessary temperature data by examining the graph or using analysis tools in LoggerPro. POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 8

9 4. Heat source light bulb wattage P = 25W 5. Initial internal temperature ( C) T Initial 1 = Maximum internal temperature ( C) T Max 1 = Final internal temperature ( C) T Final 1 = Initial room temperature ( C) T Initial 2 = Maximum room temperature ( C) T Max 2 = Final room temperature ( C) T Final 2 = Heating time (s) t 1 = 20 min = 1200 sec 12. Cooling time (s) t 2 = 20 min = 1200 sec Design Evaluation Calculations: Constants: ρ: 1.20 kg/m 3 (density of air, Greek letter rho) C p : 1000 J/kg C (specific heat capacity of air) All calculations are based on the combination of both your composite insulation material and the acrylic heat transfer apparatus material. 1. Mass of air being heated Select equation(s). Mass = volume x density, m = V x ρ List all known and unknown values. V = m 3 ρ = 1.20 kg/m 3 Substitute known values into equation(s). m = ( m 3 )(1.20 kg/m 3 ) Simplify and solve for mass (m, in kg). m = kg POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 9

10 2. Energy gained by the air in the box during heating Q (heat) in J (joules). Select equation(s). Q = m x C p x ΔT List all known and unknown values. m = kg Cp = 1000 J/kg C T(start) = 22.5 C T(max) = 54.2 C Substitute known values into equation(s). Q = ( kg)(1000 J/kg C)( C) Simplify and solve for energy gained Q (heat). Q = J 3. Energy lost by the air in the box during cooling Q (cool) in J (joules). Select equation(s). Q = m x C p x ΔT List all known and unknown values. m = kg Cp = 1000 J/kg C T(max) =54.2 C T(max) = 40.4 C Substitute known values into equation(s). Q = ( kg)(1000 J/kg C)( C) Simplify and solve for energy lost Q (cool). Q = J POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 10

11 4. Net energy retained within the box Q (net) in J (joules). Select equation(s). Q(net) = Q(heat) Q(cool) List all known and unknown values. Q(heat) = J Q(cool) = 64.58J Substitute known values into equation(s). Q(net) = J J Simplify and solve for net energy retained Q (net). Q(net) = J 5. A qualitative measure of your insulating ability is the difference between the maximum inside temperature and the maximum outside temperature (larger is better). T in (max) = T out (max) = ΔT(max) = 54.2 C 28.2 C 26.0 C 6. Compare your results with those of some other teams. Q (net): ΔT (max) = (team 1) Q (net): ΔT (max) = (team 2) Q (net): ΔT (max) = (team 3) POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 11

12 Conclusion 1. Explain how your house might lose energy through radiation, convection, and conduction. 2. What modifications could be made to your team s insulation design that allow for more energy efficiency? 3. Which beverage would be more beneficial for cooling you on a hot summer day a cup of ice cold water or a cup of hot cocoa? Justify your choice. 4. How do birds insulate their bodies to prevent energy loss on the skin s surface? 5. Suppose that you are sitting close to a campfire. You decide to clean your glasses and notice that your eyes feel warmer without your glasses. Explain this phenomenon. 6. We wear winter coats and cover with blankets to stay warm in the winter. If the coats and blankets are not a source of energy, how do we stay warm? POE Unit 1 Lesson 1.3 Project Renewable Insulation Example Teacher Notes Page 12