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Engineering 102 . Lecture 8 – Even More Solar Oven. Administration. Solar Oven Comparisons Team HW due Dec 14 (pg . 29, Solar Oven Document) Solar Oven Excel Prediction Model Team HW due Dec. 16 ( pp. 30-33, Solar Oven Document)
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Engineering 102 Lecture 8 – Even More Solar Oven
Administration • Solar Oven Comparisons Team HW due Dec 14 (pg. 29, Solar Oven Document) • Solar Oven Excel Prediction Model Team HW due Dec. 16 (pp. 30-33, Solar Oven Document) • Excel Spreadsheets: enter angles (trig. functions) in radians, not degrees • First oven testing: Friday, Jan 6
Today’s Agenda • Solar Oven Project • Emphasis on the gain, G, from the addition of the reflectors • Video • Team Time
G: The Gain from Reflectors • See pp. 13 – 20 in Solar Oven Document • Remember our VIF* from the last lecture: * Very Important Formula IoAwt a G UwAw + UsbAsb T = Toven – Tambient= The Gain from reflector(s)
G: The Gain from Reflectors Modeling the Gain, G: Figure 3. Solar Oven Geometry with Reflectors
G: The Gain from Reflectors Where: N = the number of reflectors r = the reflectivity of the aluminum foil on the reflectors (see Table 3, page 13) M = the length of the reflectors L = the length of the oven window α = the angle by which light from the reflectors enters the window (when the window is normal to solar radiation) Equation 28, page 17
G: The Gain from Reflectors Solving for α, we can obtain the more useful lid angle, Ω: Table 4. Reflector Settings for an Oven with Θs + β = 90
Solar Oven Resource Dr. Tharp’s video from Fall, 2010: http://www2.engr.arizona.edu/~tharp/102/index.html • Excellent overview of solar oven modeling and equations • Use Internet Explorer – does not work in Firefox