5.13 The surface to be used as the absorber plate in a collector has a normal-...

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5.13 The surface to be used as the absorber plate in a collector has a normal- incidence absorptance of 0.85. The collector has a single glass cover of low iron content and KL = 0.021 per sheet. Use the data for January 10 in Boulder from Table 2.5.1. Use Equations 2.10.1 and 2.16.7 in your analysis. a Plot S and IT for slopes of 30°, 45°, 60°, and 75° as a function of hour angle (four graphs). What are the general trends? b Plot (ta) ave for the four slopes as a function of hour angle. Can you draw any general conclusions? c It is proposed that the collector design is to be modified by the addition of a second cover. For a slope of 45° compare the absorbed radiation for this Chapter 6 821 day for the two-cover collector with that of the one-cover collector. What can you speculate about the utility of second cover? d There is also the possibility of using a flat-black absorber surface which has an absorptance at normal incidence of 0.96 and an emittance of 0.86. What effect would use of this surface have on absorbed radiation for the 45° slope? 5.13 The surface to be used as the absorber plate in a collector has a normal- incidence absorptance of 0.85. The collector has a single glass cover of low iron content and KL = 0.021 per sheet. Use the data for January 10 in Boulder from Table 2.5.1. Use Equations 2.10.1 and 2.16.7 in your analysis. a Plot S and IT for slopes of 30°, 45°, 60°, and 75° as a function of hour angle (four graphs). What are the general trends? b Plot (ta) ave for the four slopes as a function of hour angle. Can you draw any general conclusions? c It is proposed that the collector design is to be modified by the addition of a second cover. For a slope of 45° compare the absorbed radiation for this Chapter 6 821 day for the two-cover collector with that of the one-cover collector. What can you speculate about the utility of second cover? d There is also the possibility of using a flat-black absorber surface which has an absorptance at normal incidence of 0.96 and an emittance of 0.86. What effect would use of this surface have on absorbed radiation for the 45° slope?

Answer rating: 100% (QA)

a To plot S and IT for slopes of 30 45 60 and 75 as a function of hour angle we first need to calculate the relevant parameters using Equations 2101 and 2167 From Table 251 we can obtain the following ... View the full answer