SOLAR COLLECTOR EXPERIMENT Statistics Project II By Charles Cox and Maxcy Dimmick

Question Which material makes the most efficient cover for a solar energy collector?

Rationale The modern world is driven by energy consumption. As natural resources become more scarce, renewable sources of energy, such as solar energy, become more attractive. Collecting, storing, and converting solar energy remains a challenge worldwide. Before we can create solutions to our energy needs using solar power, we must first understand it.

Experiment This experiment measures the heat collected by a solar collector using four different materials for the cover. The materials we tested were plastic wrap, glass, wax paper, and polyethylene.

Materials for Making the Solar Collector One large coffee can Two small coffee cans, one with a lid Hammer and nail Paintbrush and flat black paint or spray paint Small circle of cardboard

Materials for Experiment Solar Collector (See instructions) Sheet of wax paper Sheet of plastic wrap Sheet of polyethylene Pane of glass CBL and compatible calculator TI Temperature Probe Beaker of water at air temperature

How to Make the Solar Collector 1) Assemble the materials. 2) Paint the inside of the small cans flat black. 3) With a hammer and nail, punch a hole in the large can first. 4) Then insert the cardboard circle into the large can. 5) Place the small can inside of the large can and punch through the large can into the small can so that the holes align. 6) Repeat step five with the second small can.

Making the Solar Collector, cont’d 7) Cut out the center of the small lid, leaving a one-centimeter rim. 8) Stretch the piece of plastic wrap across the small can and secure with the small lid. 9) Place the small piece of cardboard inside the large can and then place the first small can inside the large one, making sure the holes for the temperature probe align.

How to set up the Data Collection with the CBL Place the Graphing calculator in the CBL and connect the cable. Connect the temperature probe to Channel 1. Push the “Apps” button and select CBL/CBR. Follow the directions on the screen for setting up the data collection.

Collecting the Data First, we inserted the temperature probe into the solar collector and started the program. We collected data every 4 seconds for 120 trials. We recorded on our data sheet every 12 seconds. Then we removed the small can and tested the next material.

Collecting the Data, cont’d We discovered that it was necessary to allow time for the probe to cool down before proceeding to the next cover. We decided to place the probe in some water to hasten the cooling process. We discovered that varying cloud cover during the experiment affected the outcome.

Organizing the Data After collecting all of our data and recording selected ordered pairs on our data sheet, we consolidated all of the data from the four trials into one calculator. We used the Link functions and the List functions to accomplish this. We were able to plot 3 of the four data sets on the graphing calculator at the same time.

Which Graphs help us analyze this data?

A line graph allows us to compare the performances of the different materials to each other over a given time interval. (Geometer’s Sketchpad)

A double bar graph displaying the high and low temperature readings from each data set allows us to compare the changes in temperature. (Excel)

Statistics Derived from Experiment Plastic Wrap Extremes: 32.9 °C, 39.3 Plastic Wrap Range: 6.4 °C Glass Extremes: 33.6 °C, 45.6 °C Glass Range: 12 °C Polyethylene Extremes: 34.4 °C, 35.3 °C Polyethylene Range: 0.9 °C Wax Paper Extremes: 30.8 °C, 37.8°C Wax Paper Range: 7 °C

Extreme Values for each Cover

A bar graph displaying the mean differences of the terminal temperatures allows us to compare the spread of these temperatures. (Excel)

Mean Differences between Terminal Temperatures of Covers Plastic Wrap: 4.03 {|6.2|, |4.4|, |1.5|} Glass: 8.17 {|6.2|, |10.6|, |7.7|} Polyethylene: 6.13 {|4.4|, |3.4|, |10.6|} Wax Paper: 4.03 {|1.5|, |7.7|, |2.9|}

Conclusion The glass cover was the most efficient material to use for the cover of the solar collector. Its temperature rose sooner and faster. Glass also had the widest range of temperatures. Its terminal temperature was significantly higher than the other three. We also concluded that the weather and the initial temperature of the probe may have unduly influenced our data—especially concerning the cover made of polyethylene.