where t;coll is an important parameter in determining the overall efficiency and expresses collector performance. If the receiver aperture is too large, thermal losses out the hole will reduce efficiency. If the receiver aperture is too small, much of the concentrated sunlight will not enter the aperture, which will also reduce the efficiency. Figure 3 is a graph of the relation between Cr, etc. calculated with equations (1-3) using selected values. For each sun image size <7f there exists an optimal receiver aperture which maximizes ?;coll. The relation between sun image size and t/coll at optimal receiver aperture is given in Fig. 4. This calculation shows that the sun image size should be 0.0112 for a collector efficiency of ?;coll>0.8. Figure 5 shows the dependence of t/coll upon receiver temperature Tt. 2. Analysis of Error from Collector The collector error 6 is function of each optical error (Jsun, <5W, Jslop<.) and is defined as follows:
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