AL-78-03-1 -- A Graphical Approach to the Efficiency of Flat-Plate Collectors PDF

Estimating the performance of a flat plate solar collector from the physical description of the collector is a cumbersome calculation and is often done with numerical, i.e., computer, techniques (Refs. 1, 2 and 3). For the equipment specifier or design engineer trying to choose a collector, the available techniques are not very practical and a simpler method is needed. It is hoped that the method described here will meet the need. The National Bureau of Standards has proposed a test procedure for solar collectors which is becoming generally accepted by collector manufacturers. Where such test data are available they should be used. However, care must be exercised because significant differences exist in test data obtained on the same collector at different test facilities. The nomogram presented here estimates collector performance simply and accurately enough for general use by those who want to compare different types of collectors or to determine the performance of a specific collector. It is expected that the designers of solar collectors will also find it useful since it provides a tool to evaluate the variation in performance to be expected from a proposed design change.